{"paper_id":"19f15759-5bcc-4dfd-8ffe-2caa33b8f4e5","body_text":"Clinical classification and management strategy for humeral unicameral bone cyst in children | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Clinical classification and management strategy for humeral unicameral bone cyst in children Wei Wang, Ming Xu, Haocheng Cui, Qian Chen, Wenqiang Xing, Kai Zheng This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7767054/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective: This study aims to describe and assess the clinical classification and management strategies for humeral unicameral bone cysts (UBCs) in children. Methods: The classification and management strategy for pediatric humeral UBCs was developed based on a review of existing literature and an evaluation of our clinical practice. A retrospective analysis of pediatric patients with humeral UBCs was conducted to preliminarily validate the proposed classification and treatment strategies. Clinical efficacy was categorized into three levels: healed, healed with defects, and persistent cyst. Results: Pediatric humeral UBCs were classified into three clinical types, each with two subtypes. Type 1 represents stable UBCs, for which a conservative “wait and see” approach is recommended. Type 2 indicates invasion and destruction of bone by UBCs, with or without stable pathological fractures. The treatment plan for Type 2 includes preferential treatment with methylprednisolone acetate (MPA) injection therapy, with surgical intervention if MPA is ineffective. Type 3 involves unstable pathological fractures caused by UBCs, for which fracture reduction, cyst curettage, bone grafting, and fixation with an elastic stable intramedullary nail (ESIN) or Kirschner wire are recommended. We followed up with 32 patients for an average of 73.2 months (range, 24–144 months). The cohort included six females and twenty-six males, with ages at presentation ranging from 3 to 14 years (mean age, 9.5 years). Nineteen patients met the classification treatment protocol, while the remaining thirteen did not. In the matching group, there was one case of Type 1, seven cases of Type 2, and eleven cases of Type 3. In the non-matching group, among the ten Type 2 patients, eight did not receive MPA injection therapy and instead underwent major surgeries, including seven cases of curettage and bone grafting and one case necessitating ESIN. The other two Type 2 patients did not receive ESIN treatment following inadequate response to MPA injection. Two Type 3 patients received MPA injection treatment, while one underwent external fixation and the other underwent curettage and bone grafting. In the matching group, ten patients achieved complete healing, eight experienced healing with defects, and one had a recurrence of UBC. In the non-matching group, six patients healed, three healed with defects, and four had recurrences. Despite numerical differences, statistical analysis did not reveal significant differences between the groups. Conclusion: The clinical classification and management strategies for humeral UBCs in children are validated by this study. The findings provide important references in clinical decision-making. Clinical classification Management strategy Unicameral bone cyst Children Humerus Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Unicameral bone cysts (UBCs), also known as simple or solitary bone cysts, are benign, fluid-filled lesions that predominantly occur in males[1–3]. UBCs represent approximately 3% of all primary bone tumors in children and adolescents[1, 2]. While UBCs are generally regarded as self-limiting lesions, they can lead to progressive bone destruction and pathological fractures, making treatment essential[2, 4]. The humerus and femur are the most common sites affected, with the humerus accounting for more than 50% of long bone lesions[5, 6]. Although UBCs have been recognized for over a century, their etiology remains unknown[1, 7]. Consequently, there is no consensus on the most effective treatment[8]. Debate persists regarding the necessity of treatment, the timing of intervention, and the most appropriate methodologies. Currently, there are several treatment options available, including observation, immobilization, injection therapy, bone grafting using autografts, allografts, or synthetic materials, open curettage followed by bone grafting, elastic stable intramedullary nail (ESIN) fixation, or a combination of these techniques[9–16]. Each approach has been associated with varying rates of success; however, there remains a risk of cyst recurrence[9]. Determining the most suitable treatment plan for different patients is a challenge that surgeons must address[17, 18]. Unlike other malignant and invasive bone tumors, the treatment of bone cysts does not focus on radical tumor excision[19]. Instead, the primary objectives of treatment are to minimize the risk of fractures and to restore bone strength and cortical thickness[1]. When prioritizing bone strength, the presence of cysts becomes a secondary concern. Physicians often have overly emphasized the removal of cysts and the prevention of recurrence, thereby neglecting the foundational purpose of treatment, which has led to many patients receiving excessive interventions. Additionally, since bone cysts are more prevalent in the humerus and femur, it is important to recognize substantial differences in weight-bearing requirements between these two sites, making it inappropriate to apply uniform treatment methods[2, 20]. This study aims to explore the following research questions: (1) Is clinical classification feasible for humeral bone cysts in children and adolescents? (2) Can a tiered treatment plan be established based on different subtypes of bone cysts? (3) Does tiered therapy have clinical significance? Methods Inclusion and Exclusion Criteria  Patients were selected based on the following inclusion criteria: (i) age under 14 years; (ii) diagnosis confirmed through X-ray, CT, or MR imaging and pathological assessment; (iii) the presence of UBCs located in the humerus; (iv) a minimum follow-up period of two years. The exclusion criteria included: (i) patients lacking intact clinical and radiographic data, or (ii) patients unable to cooperate in completing clinical evaluations.  Patient Characteristics A retrospective review was conducted of thirty-two patients with UBCs who received treatment between January 2012 to January 2022 at the PLA 960th Hospital and Linyi People's Hospital. Treatment modalities included injection of methylprednisolone acetate (MPA), curettage with bone grafting, ESIN, and various combinations of these approaches. Medical records for each patient were thoroughly examined to collect data on several variables, including gender, age, symptoms, presence or absence of pathological fractures, radiographic findings, surgical procedures, and clinical outcomes. We had prior ethics approval from Institutional Ethical Committee of The 960th Hospital of the PLA Joint Logistice Support Force (NO: 2018022) and adult patient consent was obtained for this study. The written informed consent was obtained from all subjects or their legal guardian. The research was carried out according to the principles set out in the Declaration of Helsinki 1964 and all subsequent revisions.  Surgical Technique  MPA Injection: Patients were treated using the two-needle technique described by Scaglietti et al. under general anesthesia[21]. During the initial treatment, we performed a scraping of the cyst wall, which was subsequently send for pathological examination. The aspiration of bright yellow fluid helped confirm the presence of UBCs based on intraoperative findings. A postoperative histopathological examination further supported this diagnosis. The procedure was conducted under C-arm guidance, with two needles inserted at the thinnest part of the cyst. The cyst was repeatedly infused with sterile water for injection before the MPA was administered. Following injection, pressure was applied to the cyst for 15 minutes to prevent overflow. The volume of MPA injected was based on the patient’s age, body weight, and bone cyst size, ranging from 40 to 80 mg for smaller cysts or younger patients, and up to 120 mg for larger cysts. ESIN Implantation: A 1 cm incision was marked on the medial and lateral condyles of the humerus, positioned away from the bone cyst. A drill hole was then created in the cortical bone to facilitate the implantation of the ESIN. The ESIN, shaped either in a “C” or “S” configuration, was slowly inserted into the medullary cavity, traversing the entire UBC, with or without the presence of a fracture, until it reached the normal bone of the proximal humerus. Throughout the procedure, C-arm fluoroscopy was used to ensure the accurate placement of the ESIN. Once the ESIN was successfully implanted, the tail of the nail was bent to achieve complete subcutaneous embedding. Curettage and bone grafting: UBCs were accessed through a longitudinal incision, and a suitably sized window was created on the surface of the cysts. The soft tissue lining the walls of the UBCs was thoroughly curetted and sent to the pathology department for diagnostic confirmation. The resulting cavity was filled with allogeneic bone or synthetic bone material. In cases where UBCs were adjacent to the epiphyseal region and accompanied by unstable fractures, autologous fibular bone grafting and Kirschner wire fixation were employed following fracture reduction. Subsequently, the remaining void in the cavity was also filled with allogeneic bone or synthetic bone material. To ensure stable fixation, Kirschner wires were typically inserted through the epiphyseal plate and were removed 6 to 8 weeks post-surgery. Patients utilized a shoulder sling for 2 to 4 weeks postoperatively. Those with fractures attended follow-up visits every 3 weeks until union was achieved, after which follow-up continued at 3-month intervals. Patients without fractures exhibited normal upper limb movement, while those with fractures commenced shoulder joint function exercises following fracture healing. Radiographic evaluations were conducted at each follow-up appointment. Cyst healing was assessed using the modified Neer scale, as proposed by Chang et al[22]. Clinical classification The imaging manifestations and biological behavior of UBCs serve as essential criteria for clinical classification. UBCs can be categorized into active and stable types based on their level of activity. Key factors for further classification include the location of active bone cysts invading the humeral bone, the extent of cortical destruction, the occurrence of pathological fractures, and the stability of the bone after such fractures.  Statistical Analysis Continuous variables such as age and time of follow-up were expressed as the mean and the standard deviation. Categorical variables such as recurrence were described as a percentage rate. All analyses were performed using IBM SPSS Version 26 (SPSS Statistics V26, IBM Corporation, Somers, New York). Results Clinical classification Childhood humeral UBCs are classified into three clinical types, each comprising two subtypes (Fig. 1). Type 1 represents stable UBCs. Subtype 1a refers to UBCs located in the bone marrow cavity with no significant invasion of the cortical bone; a hardened edge is typically visible surrounding the cyst. Subtype 1b is characterized by swelling of the bone, with surrounding bone that is markedly thickened and enveloping the cyst. Type 2 indicates UBCs that invade and destroy bone, with or without stable pathological fractures. Subtype 2a designates UBCs located in the diaphysis, while Subtype 2b refers to those positioned below the epiphyseal plate. Type 3 involves unstable pathological fractures resulting from UBCs. Similar to Type 2, this type is divided into Subtype 3a and Subtype 3b, based on tumor location. Clinical treatment recommendations vary according to subtype: for Type 1 UBCs, a “watch-and-wait” approach is advised. For Type 2 UBCs, an initial treatment with MPA injection is recommended; if 2-3 attempts are ineffective, consideration should be given to treating with ESIN or bone grafting surgery. In the case of Type 3 UBCs, treatment is recommended to involve a combination of ESIN and bone grafting, or bone grafting with Kirschner wire fixation (Fig. 2). Clinical Characteristics The cohort consisted of six females and twenty-six males, with ages at presentation ranging from 3 to 14 years (mean age: 9.5 ± 3.1 years). Patients were classified into a matching group and a non-matching group based on their adherence to the clinical classification treatment protocol. Nineteen patients met the criteria for the classification treatment protocol, while the remaining thirteen did not. In the matching group, there was 1 case of Type 1 UBC, 7 cases of Type 2 UBC, and 11 cases of Type 3 UBC. All patients in this group received treatment in accordance with the recommended plan. In the non-matching group, there was 1 case of Type 1 UBC, 10 cases of Type 2 UBC, and 2 cases of Type 3 UBC. Of these patients, one Type 1b case did not follow the “watch-and-wait” approach and instead underwent direct curettage and bone grafting surgery. Among Type 2 patients, 8 did not receive MPA injection treatment and proceeded directly to major surgical interventions, which included 7 cases of curettage with bone grafting and 1 case of ESIN. The remaining 2 patients did not receive ESIN treatment due to inadequate response to the repeated MPA injections. For Type 3 patients, one was treated with MPA injection and external fixation, while the other received curettage and bone grafting. Clinical efficacy was assessed at three levels: healed, healed with defects, and persistent cyst. In matching group, 10 patients achieved healing, 8 patients healed with defects, and 1 patient experienced recurrence of UBCs. In the non-matching group, 6 patients healed, 3 patients healed with defects, and 4 patients experienced recurrence of UBCs (Table 1). The clinical efficacy of different treatment methods was also evaluated. A total of 10 patients received MPA injections, with a combined total 31 treatments, ranging from 1 to 7 injections per patient. Of these, only 1 case achieved complete healing, while 8 patients healed with defects, and 1 patient experienced a recurrence of UBCs (Fig. 3). Additionally, 12 patients underwent curettage and bone grafting, resulting in 9 cases of complete healing, 1 case that healed with defects, and 2 cases of UBC recurrence (Fig. 4). Furthermore, 9 patients were treated with ESIN, with 6 patients achieving complete healing, 1 patient healing with defects, and 2 patients experiencing UBC recurrence (Fig. 5). Discussion To date, the pathogenesis of UBCs remains unclear. Several hypotheses have been proposed in literatures[1]. The most widely accepted mechanism suggests that increased intracavitary osseous pressure and inflammation occur in rapidly growing and remodeling areas of cancellous bone[23]. This theory has informed the development of treatment approaches such as puncture decompression and MPA injection therapy, which have shown partial success in clinical practice[9, 19, 24]. Another recognized mechanism is the obstruction of venous drainage, which supports the use of ESIN as a treatment option that facilitates internal drainage while addressing pathological fractures. Clinical outcomes have confirmed the efficacy of this treatment method[9, 11, 25]. However, despite the various treatment approaches, systematic literature analyses indicate that some patients do experience recurrence[9]. This observation suggests that the pathogenesis of UBCs is complex and that treatment strategies should be tailored accordingly[1, 9, 24]. For self-limiting conditions like UBCs, it is essential to balance patient benefits, surgical trauma, and the risk of complications during treatment. The clinical classification and treatment strategies for pediatric humeral UBCs proposed in this study are informed by this consideration. UBCs are commonly recognized as benign tumors that exhibit self-limiting behavior[1]. However, there is limited literature available that elucidates which UBC types are amenable to observation. In this study, we propose a clinical classification for humeral UBCs in children, specifically identifying Type 1 UBCs as lesions that remain localized within the bone without causing bone destruction. These lesions can lead to bone expansion but are surrounded by dense cortical bone, thus maintaining good bone integrity. The schematic diagram and imaging presented in this article aim to assist readers in understanding and visualizing what we term \"stable UBCs\". In contrast, Types 2 and 3 UBCs indicate advanced disease stages. The critical distinction lies in the presence of unstable pathological fractures associated with Type 3 UBCs. Based on anatomical variations in invasion and bone destruction, UBCs are further divided into two subtypes: a and b. For Type 2 UBCs, we recommend initial treatment with MPA injection therapy. If two to three injections are ineffective, surgical intervention may be warranted. In the case of Type 3 UBCs, surgery is preferred to prevent deformities due to significant unstable fractures. The primary objective of this clinical classification is to facilitate tiered treatment strategies. A \"watch-and-wait\" approach may be employed for stabilizing UBCs. Minimally invasive methods are preferred for advanced UBCs that do not present with unstable pathological fractures. This study advocates for MPA injection therapy because of its ease of administration, lower cost, and reduced risk of complications. Although the overall cure rate for this approach is modest, many patients achieve partial resolution, which fulfills therapeutic objectives. However, a discrepancy exists within this retrospective study regarding the treatment protocols; many patients did not receive MPA therapy. Our findings suggest that MPA injection therapy yields acceptable outcomes for pediatric UBCs and should be pursued prior to considering more aggressive treatments. While some authors have proposed using bone marrow concentrate (BMC) injection therapy, we do not recommend this approach. This stance is based on several observations: firstly, systematic literature analyses do not demonstrate superior clinical efficacy for BMC compared to MPA; secondly, the BMC injection process involves additional trauma; and thirdly, BMC injections may elevate surgical risks, such as pulmonary embolism[9, 26]. Surgical treatment plans for patients with Type 2 and Type 3 UBCs generally involve curettage and bone grafting, Kirschner wire internal fixation, and ESIN. Curettage and bone grafting represent an efficient and reliable surgical method[5, 9, 13]. In cases where a UBC is adjacent to an epiphyseal plate and an unstable fracture is present, structural bone grafting using autologous fibula transplantation can mitigate the risk of bone graft collapse[12, 27]. Kirschner wire fixation enhances stability; thinner wires, when placed through the epiphyseal plate, do not interfere with normal growth in children. Removing the Kirschner wires 6-8 weeks post-surgery minimizes additional trauma. Currently, ESIN combined with bone grafting is considered the most effective treatment for UBCs, supported by numerous clinical reports[9, 28]. A critical consideration remains regarding the optimal timing for ESIN removal. Continuous drainage through the ESIN may positively influence UBC treatment; however, as bone grows, the external portion of the ESIN becomes encapsulated, complicating internal drainage and subsequent removal[6, 29]. The potential for UBC recurrence in young children following ESIN removal warrants further attention[8]. While the possibility of recurrence exists with any treatment method, reducing Type 2 or Type 3 UBCs to Type 1 presents notable clinical significance. UBCs represent a unique clinical challenge, as the treatment-related trauma may outweigh the risks associated with the disease itself. Thus, effective management should take precedence over aggressive treatment[30]. It is essential to evaluate whether current treatment protocols are excessive and whether they confer tangible clinical benefits to patients. We believe that further research into UBCs will aid in minimizing unnecessary iatrogenic harm. A comprehensive understanding of UBC classification and treatment strategies will empower surgeons and patients in making informed clinical decisions. Limitations Our study had several limitations. First, the statistical analysis revealed no significant differences between the various groups. This lack of distinction may be attributed to the retrospective nature of the clinical cases examined and potential biases stemming from previous interpretations. Second, there were disparities in the number of patients across different types, particularly for type 1 patients, who do not require treatment intervention and are typically monitored during outpatient follow-ups. Consequently, the data for hospitalized type 1 patients is limited. Third, the follow-up duration varied significantly, ranging from 24 to 144 months. Conclusion In conclusion, the clinical classification, tiered treatment strategies, and management of pediatric humeral UBCs hold significant clinical relevance. Declarations Author Contributions KZ and WW analyzed and interpreted the patient data regarding the treatment options. KZ put forward the research idea and participated in result interpretation and writing. KZ, WW, WX, MX, QC, and HC were involved in the development of research. KZ, WW, WX, and MX had designed and processed surgical technique. All authors performed the patients’ treatments and KZ, MX, HC, and WW performed the patients’ follow-up. All authors read and approved the final manuscript. Funding Not applicable. Data Availability Statement The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Ethics Statement We had prior ethics approval from Institutional Ethical Committee of The 960th Hospital of the PLA Joint Logistice Support Force (NO: 2018022) and adult patient consent was obtained for this study. The written informed consent was obtained from all subjects or their legal guardian. The research was carried out according to the principles set out in the Declaration of Helsinki 1964 and all subsequent revisions. Consent to Participate declaration Informed consent was obtained from the parents or legal guardians of all minor participants included in the study. Additionally, age-appropriate assent was also obtained from the children themselves whenever possible. Consent for publication Not Applicable. Clinical trial number Not Applicable. Competing interests The authors declare that they have no competing interests. References Noordin S, Allana S, Umer M, Jamil M, Hilal K, Uddin N. Unicameral bone cysts: Current concepts. Ann Med Surg. 2018;34 June:43–9. Pretell-Mazzini J, Murphy RF, Kushare I, Dormans JP. Unicameral bone cysts: General characteristics and management controversies. J Am Acad Orthop Surg. 2014;22:295–303. Kadhim M, Thacker M, Kadhim A, Holmes L. Treatment of unicameral bone cyst: Systematic review and meta analysis. J Child Orthop. 2014;8:171–91. Urakawa H, Tsukushi S, Hosono K, Sugiura H, Yamada K, Yamada Y, et al. Clinical factors affecting pathological fracture and healing of unicameral bone cysts. BMC Musculoskelet Disord. 2014;15:1–9. Mavčič B, Saraph V, Gilg MM, Bergovec M, Brecelj J, Leithner A. 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Factors which can influence elastic stable intramedullary nailing removal in healed bone cysts in children. Sci Rep. 2024;14:1–7. van Geloven TPG, van der Heijden L, Laitinen MK, Campanacci DA, Döring K, Dammerer D, et al. As simple as it sounds? The treatment of simple bone cysts in the proximal femur in children and adolescents: Retrospective multicenter EPOS study of 74 patients. J Child Orthop. 2024;18:85–95. Table Table 1 demographic data for patients with UBCs Consistent Inconsistent p Gender 0.687 Male 15 11 Female 4 2 Age, years (SD) 9.8±2.9 9.1±3.4 0.526 Clinical classification 0.054 Type 1 1 1 Type 2 7 10 Type 3 11 2 Treatment 0.122 Watch and wait 1 0 MPA injection 7 3 Curettage + bone graft ± internal fixation 4 8 ESIN + curettage + bone graft 7 2 Follow-up, months (SD) 64.9 ± 36.5 85.3 ± 44.9 0.232 Curative effect 0.129 Healed 10 6 Healed with defects 8 3 Persistent cyst 1 4 Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-7767054\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":546246742,\"identity\":\"7e97fd5a-3478-4467-879b-43a0f013c7f8\",\"order_by\":0,\"name\":\"Wei Wang\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Linyi People’s Hospital\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Wei\",\"middleName\":\"\",\"lastName\":\"Wang\",\"suffix\":\"\"},{\"id\":546246744,\"identity\":\"c639e363-5419-4208-ac54-855af89c1414\",\"order_by\":1,\"name\":\"Ming 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17:50:26\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":210054,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eChildhood humeral unicameral bone cysts (UBCs) are classified into three clinical types, each encompassing two subtypes. This figure illustrates the typical imaging manifestations associated with these categories. A: Subtype 1a represents a stable UBC located within the bone marrow cavity, characterized by no significant cortical bone invasion and a discernible hardened edge. B: Subtype 1b is a UBC that induces bone swelling, accompanied substantial thickening of the surrounding bone. C: Type 2 indicates bone invasion and destruction by UBCs, with the potential for stable pathological fractures. If the UBC is situated in the diaphysis, it is categorized as subtype 2a. D: Subtype 2b UBC is located below the epiphyseal plate. E: Type 3 refers to unstable pathological fracture resulting from UBCs; when the UBC is in the diaphysis, it is classified as subtype 3a. F: Subtype 3b UBC is located beneath the epiphyseal plate.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-7767054/v1/ad27018c1d8bd963448e9998.png\"},{\"id\":96603340,\"identity\":\"34758767-bbb1-4b22-847d-ad31fcbcb229\",\"added_by\":\"auto\",\"created_at\":\"2025-11-24 09:08:22\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":180390,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eClinical treatment recommendations vary according to the different types and subtypes of UBCs.For Type 1 UBCs, “watch and wait” is advised. Type 2 UBCs should initially receive MPA injection therapy. If two to three injection attempts prove ineffective, further interventions such as elastic stable intramedullary nailing (ESIN) or bone grafting surgery may be considered. Type 3 UBCs typically require treatment with a combination of ESIN and bone grafting, or bone grafting paired with Kirschner wire fixation.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-7767054/v1/4c8122847fca8b437795a7e5.png\"},{\"id\":96491164,\"identity\":\"14deadcb-ac77-4f3c-9ce5-ac96da2c08e8\",\"added_by\":\"auto\",\"created_at\":\"2025-11-21 17:50:26\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":233919,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eAn 8-year-old male patient diagnosed with subtype 1b underwent “watch and wait” for three years. The patient was initially diagnosed with a humeral UBC in July 2021 (A) and entered a watchful waiting period. Follow-up X-ray examinations at six months (B), one year (C), one and a half years (D), two years (E), and three years (F) revealed a stable lesion with no significant progression.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-7767054/v1/756dc6b583e02de6625e9dd7.png\"},{\"id\":96491167,\"identity\":\"b97a3de4-7308-439a-a747-c86edac4099c\",\"added_by\":\"auto\",\"created_at\":\"2025-11-21 17:50:26\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":172161,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eA 7-year-old male patient diagnosed with a subtype 2b UBC underwent MPA injection treatment on two occasions. A: The patient was diagnosed with a UBC in March 2019, during which imaging revealed extensive osteolytic changes. B: Following the diagnosis, the patient received MPA injection therapy. C: Three days post-treatment, re-examination of the imaging displayed an extremely low-density area within the cyst, indicating the complete extraction of cystic fluid components. D: Follow-up imaging three months after treatment revealed extensive calcification within the bone cyst. E: One year post-surgery, partial recurrence of the bone cyst was noted, although the surrounding bone demonstrated good stability. F: Two years after treatment, follow-up imaging indicated an increase in the size of the bone cyst, which had moved away from the epiphyseal plate, prompting a second administration of MPA treatment. G: Six months following the second MPA injection treatment, the patient's follow-up imaging demonstrated partial calcification of the bone cyst. H: One year after the second treatment, imaging revealed the presence of residual bone cysts. I: Two years following the second treatment, imaging showed reparative features within the bone cyst, indicating a stable condition. J: After three years of secondary treatment, imaging confirmed that the bone cyst remained stable.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-7767054/v1/32d5fb94300b9022f59ce5c9.png\"},{\"id\":96491172,\"identity\":\"fa4dc16f-0a8f-445b-8db2-271f18627525\",\"added_by\":\"auto\",\"created_at\":\"2025-11-21 17:50:26\",\"extension\":\"png\",\"order_by\":5,\"title\":\"Figure 5\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":269048,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eA 12-year-old male patient diagnosed with subtype 3a underwent ESIN and bone grafting. A: The patient presented with bone fractures after minor trauma in July 2022 and was diagnosed with UBC accompanied by unstable pathological fractures. Imaging revealed osteolytic lesions situated well away from the epiphyseal plate. B: The patient received ESIN fixation along with bone grafting. C: Postoperative follow-up imaging conducted two weeks later revealed satisfactory fracture reduction; the UBC lesion had been excised, with the cavity filled with artificial bone. D: Six weeks post-surgery, imaging demonstrated the formation of an external callus at the fracture site. E: Three months after the operation, follow-up examinations indicated complete fracture healing and gradual absorption of the artificial bone. F: Six months post-surgery, follow-up examinations confirmed effective fracture repair and remodeling. G: One year after the procedure, the artificial bone exhibited local absorption and calcification as part of the repair process. H: At one-and-a-half years post-surgery, the lesion showed significant healing, with no recurrence of the UBC. I: Two years after the operation, ESIN was removed, and residual repair was performed locally.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"5.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-7767054/v1/c67be347a8b3bec6ecb0b9c6.png\"},{\"id\":101943523,\"identity\":\"04e302ed-5ab2-4c6f-98a5-b1f2a1617682\",\"added_by\":\"auto\",\"created_at\":\"2026-02-05 09:42:13\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":2049390,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-7767054/v1/f0e9fee5-6f22-49d2-8f2a-3ad1d4d00c8f.pdf\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Clinical classification and management strategy for humeral unicameral bone cyst in children\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eUnicameral bone cysts (UBCs), also known as simple or solitary bone cysts, are benign, fluid-filled lesions that predominantly occur in males[1–3]. UBCs represent approximately 3% of all primary bone tumors in children and adolescents[1, 2].\\u0026nbsp;While UBCs are generally regarded as self-limiting lesions, they can lead to progressive bone destruction and pathological fractures, making treatment essential[2, 4].\\u0026nbsp;The humerus and femur are the most common sites affected, with the humerus accounting for more than 50% of long bone lesions[5, 6].\\u003c/p\\u003e\\n\\u003cp\\u003eAlthough UBCs have been recognized for over a century, their etiology remains unknown[1, 7]. Consequently, there is no consensus on the most effective treatment[8]. Debate persists regarding the necessity of treatment, the timing of intervention, and the most appropriate methodologies. Currently, there are several treatment options available, including observation, immobilization, injection therapy, bone grafting using autografts, allografts, or synthetic materials, open curettage followed by bone grafting, elastic stable intramedullary nail (ESIN) fixation, or a combination of these techniques[9–16]. Each approach has been associated with varying rates of success; however, there remains a risk of cyst recurrence[9]. Determining the most suitable treatment plan for different patients is a challenge that surgeons must address[17, 18].\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eUnlike other malignant and invasive bone tumors, the treatment of bone cysts does not focus on radical tumor excision[19]. Instead, the primary objectives of treatment are to minimize the risk of fractures and to restore bone strength and cortical thickness[1]. When prioritizing bone strength, the presence of cysts becomes a secondary concern. Physicians often have overly emphasized the removal of cysts and the prevention of recurrence, thereby neglecting the foundational purpose of treatment, which has led to many patients receiving excessive interventions. Additionally, since bone cysts are more prevalent in the humerus and femur, it is important to recognize substantial differences in weight-bearing requirements between these two sites, making it inappropriate to apply uniform treatment methods[2, 20]. This study aims to explore the following research questions: (1) Is clinical classification feasible for humeral bone cysts in children and adolescents? (2) Can a tiered treatment plan be established based on different subtypes of bone cysts? (3) Does tiered therapy have clinical significance?\\u003c/p\\u003e\"},{\"header\":\"Methods\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eInclusion and Exclusion Criteria\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e \\u0026nbsp; \\u0026nbsp;Patients were selected based on the following inclusion criteria: (i) age under 14 years; (ii) diagnosis confirmed through X-ray, CT, or MR imaging and pathological assessment; (iii) the presence of UBCs located in the humerus; (iv) a minimum follow-up period of two years. The exclusion criteria included: (i) patients lacking intact clinical and radiographic data, or (ii) patients unable to cooperate in completing clinical evaluations.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePatient Characteristics\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eA retrospective review was conducted of thirty-two patients with UBCs who received treatment between January 2012 to January 2022 at the PLA 960th Hospital and Linyi People's Hospital. Treatment modalities included injection of methylprednisolone acetate (MPA), curettage with bone grafting, ESIN, and various combinations of these approaches. Medical records for each patient were thoroughly examined to collect data on several variables, including gender, age, symptoms, presence or absence of pathological fractures, radiographic findings, surgical procedures, and clinical outcomes.\\u003c/p\\u003e\\n\\u003cp\\u003eWe had prior ethics approval from Institutional Ethical Committee of The 960th Hospital of the PLA Joint Logistice Support Force (NO: 2018022) and adult patient consent was obtained for this study. The written informed consent was obtained from all subjects or their legal guardian. The research was carried out according to the principles set out in the Declaration of Helsinki 1964 and all subsequent revisions.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eSurgical Technique\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eMPA Injection:\\u0026nbsp;\\u003c/strong\\u003ePatients were treated using the two-needle technique described by Scaglietti et al. under general anesthesia[21]. During the initial treatment, we performed a scraping of the cyst wall, which was subsequently send for pathological examination. The aspiration of bright yellow fluid helped confirm the presence of UBCs based on intraoperative findings. A postoperative histopathological examination further supported this diagnosis. The procedure was conducted under C-arm guidance, with two needles inserted at the thinnest part of the cyst. The cyst was repeatedly infused with sterile water for injection before the MPA was administered. Following injection, pressure was applied to the cyst for 15 minutes to prevent overflow. The volume of MPA injected was based on the patient’s age, body weight, and bone cyst size, ranging from 40 to 80 mg for smaller cysts or younger patients, and up to 120 mg for larger cysts.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eESIN Implantation:\\u0026nbsp;\\u003c/strong\\u003eA 1 cm incision was marked on the medial and lateral condyles of the humerus, positioned away from the bone cyst. A drill hole was then created in the cortical bone to facilitate the implantation of the ESIN. The ESIN, shaped either in a “C” or “S” configuration, was slowly inserted into the medullary cavity, traversing the entire UBC, with or without the presence of a fracture, until it reached the normal bone of the proximal humerus. Throughout the procedure, C-arm fluoroscopy was used to ensure the accurate placement of the ESIN. Once the ESIN was successfully implanted, the tail of the nail was bent to achieve complete subcutaneous embedding.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCurettage and bone grafting:\\u0026nbsp;\\u003c/strong\\u003eUBCs were accessed through a longitudinal incision, and a suitably sized window was created on the surface of the cysts. The soft tissue lining the walls of the UBCs was thoroughly curetted and sent to the pathology department for diagnostic confirmation. The resulting cavity was filled with allogeneic bone or synthetic bone material. In cases where UBCs were adjacent to the epiphyseal region and accompanied by unstable fractures, autologous fibular bone grafting and Kirschner wire fixation were employed following fracture reduction. Subsequently, the remaining void in the cavity was also filled with allogeneic bone or synthetic bone material. To ensure stable fixation, Kirschner wires were typically inserted through the epiphyseal plate and were removed 6 to 8 weeks post-surgery.\\u003c/p\\u003e\\n\\u003cp\\u003ePatients utilized a shoulder sling for 2 to 4 weeks postoperatively. Those with fractures attended follow-up visits every 3 weeks until union was achieved, after which follow-up continued at 3-month intervals. Patients without fractures exhibited normal upper limb movement, while those with fractures commenced shoulder joint function exercises following fracture healing. Radiographic evaluations were conducted at each follow-up appointment. Cyst healing was assessed using the modified Neer scale, as proposed by Chang et al[22].\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eClinical classification\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe imaging manifestations and biological behavior of UBCs serve as essential criteria for clinical classification. UBCs can be categorized into active and stable types based on their level of activity. Key factors for further classification include the location of active bone cysts invading the humeral bone, the extent of cortical destruction, the occurrence of pathological fractures, and the stability of the bone after such fractures.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eStatistical Analysis\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eContinuous variables such as age and time of follow-up were expressed as the mean and the standard deviation. Categorical variables such as recurrence were described as a percentage rate. All analyses were performed using IBM SPSS Version 26 (SPSS Statistics V26, IBM Corporation, Somers, New York).\\u003c/p\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eClinical classification\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eChildhood humeral UBCs are classified into three clinical types, each comprising two subtypes (Fig. 1).\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eType 1 represents stable UBCs. Subtype 1a refers to UBCs located in the bone marrow cavity with no significant invasion of the cortical bone; a hardened edge is typically visible surrounding the cyst. Subtype 1b is characterized by swelling of the bone, with surrounding bone that is markedly thickened and enveloping the cyst.\\u003c/p\\u003e\\n\\u003cp\\u003eType 2 indicates UBCs that invade and destroy bone, with or without stable pathological fractures. Subtype 2a designates UBCs located in the diaphysis, while Subtype 2b refers to those positioned below the epiphyseal plate.\\u003c/p\\u003e\\n\\u003cp\\u003eType 3 involves unstable pathological fractures resulting from UBCs. Similar to Type 2, this type is divided into Subtype 3a and Subtype 3b, based on tumor location.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eClinical treatment recommendations vary according to subtype: for Type 1 UBCs, a “watch-and-wait” approach is advised. For Type 2 UBCs, an initial treatment with MPA injection is recommended; if 2-3 attempts are ineffective, consideration should be given to treating with ESIN or bone grafting surgery. In the case of Type 3 UBCs, treatment is recommended to involve a combination of ESIN and bone grafting, or bone grafting with Kirschner wire fixation (Fig. 2).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eClinical Characteristics\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe cohort consisted of six females and twenty-six males, with ages at presentation ranging from 3 to 14 years (mean age: 9.5 ± 3.1 years). Patients were classified into a matching group and a non-matching group based on their adherence to the clinical classification treatment protocol. Nineteen patients met the criteria for the classification treatment protocol, while the remaining thirteen did not. In the matching group, there was 1 case of Type 1 UBC, 7 cases of Type 2 UBC, and 11 cases of Type 3 UBC.\\u0026nbsp;All patients in this group received treatment in accordance with the recommended plan. In the non-matching group, there was 1 case of Type 1 UBC, 10 cases of Type 2 UBC, and 2 cases of Type 3 UBC. Of these patients, one Type 1b case did not follow the “watch-and-wait” approach and instead underwent direct curettage and bone grafting surgery. Among Type 2 patients, 8 did not receive MPA injection treatment and proceeded directly to major surgical interventions, which included 7 cases of curettage with bone grafting and 1 case of ESIN. The remaining 2 patients did not receive ESIN treatment due to inadequate response to the repeated MPA injections. For Type 3 patients, one was treated with MPA injection and external fixation, while the other received curettage and bone grafting. Clinical efficacy was assessed at three levels: healed,\\u0026nbsp;healed with defects, and persistent cyst. In matching group, 10 patients achieved healing, 8 patients healed with defects, and 1 patient experienced recurrence of UBCs. In the non-matching group, 6 patients healed, 3 patients healed with defects, and 4 patients experienced recurrence of UBCs (Table 1).\\u003c/p\\u003e\\n\\u003cp\\u003eThe clinical efficacy of different treatment methods was also evaluated. A total of 10 patients received MPA injections, with a combined total 31 treatments, ranging from 1 to 7 injections per patient. Of these, only 1 case achieved complete healing, while 8 patients healed with defects, and 1 patient experienced a recurrence of UBCs (Fig. 3). Additionally, 12 patients underwent curettage and bone grafting, resulting in 9 cases of complete healing, 1 case that healed with defects, and 2 cases of UBC recurrence (Fig. 4). Furthermore, 9 patients were treated with ESIN, with 6 patients achieving complete healing, 1 patient healing with defects, and 2 patients experiencing UBC recurrence (Fig. 5).\\u003c/p\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eTo date, the pathogenesis of UBCs remains unclear. Several hypotheses have been proposed in literatures[1].\\u0026nbsp;The most widely accepted mechanism suggests that increased intracavitary osseous pressure and inflammation occur in rapidly growing and remodeling areas of cancellous bone[23]. This theory has informed the development of treatment approaches such as puncture decompression and MPA injection therapy, which have shown partial success in clinical practice[9, 19, 24]. Another recognized mechanism is the obstruction of venous drainage, which supports the use of ESIN as a treatment option that facilitates internal drainage while addressing pathological fractures. Clinical outcomes have confirmed the efficacy of this treatment method[9, 11, 25].\\u0026nbsp;However, despite the various treatment approaches, systematic literature analyses indicate that some patients do experience recurrence[9]. This observation suggests that the pathogenesis of UBCs is complex and that treatment strategies should be tailored accordingly[1, 9, 24]. For self-limiting conditions like UBCs, it is essential to balance patient benefits, surgical trauma, and the risk of complications during treatment. The clinical classification and treatment strategies for pediatric humeral UBCs proposed in this study are informed by this consideration.\\u003c/p\\u003e\\n\\u003cp\\u003eUBCs are commonly recognized as benign tumors that exhibit self-limiting behavior[1]. However, there is limited literature available that elucidates which UBC types are amenable to observation. In this study, we propose a clinical classification for humeral UBCs in children, specifically identifying Type 1 UBCs as lesions that remain localized within the bone without causing bone destruction. These lesions can lead to bone expansion but are surrounded by dense cortical bone, thus maintaining good bone integrity. The schematic diagram and imaging presented in this article aim to assist readers in understanding and visualizing what we term \\\"stable UBCs\\\". In contrast, Types 2 and 3 UBCs indicate advanced disease stages. The critical distinction lies in the presence of unstable pathological fractures associated with Type 3 UBCs. Based on anatomical variations in invasion and bone destruction, UBCs are further divided into two subtypes: a and b. For Type 2 UBCs, we recommend initial treatment with MPA injection therapy. If two to three injections are ineffective, surgical intervention may be warranted. In the case of Type 3 UBCs, surgery is preferred to prevent deformities due to significant unstable fractures. The primary objective of this clinical classification is to facilitate tiered treatment strategies. A \\\"watch-and-wait\\\" approach may be employed for stabilizing UBCs. Minimally invasive methods are preferred for advanced UBCs that do not present with unstable pathological fractures. This study advocates for MPA injection therapy because of its ease of administration, lower cost, and reduced risk of complications. Although the overall cure rate for this approach is modest, many patients achieve partial resolution, which fulfills therapeutic objectives. However, a discrepancy exists within this retrospective study regarding the treatment protocols; many patients did not receive MPA therapy. Our findings suggest that MPA injection therapy yields acceptable outcomes for pediatric UBCs and should be pursued prior to considering more aggressive treatments. While some authors have proposed using bone marrow concentrate (BMC) injection therapy, we do not recommend this approach. This stance is based on several observations: firstly, systematic literature analyses do not demonstrate superior clinical efficacy for BMC compared to MPA; secondly, the BMC injection process involves additional trauma; and thirdly, BMC injections may elevate surgical risks, such as pulmonary embolism[9, 26]. Surgical treatment plans for patients with Type 2 and Type 3 UBCs generally involve curettage and bone grafting, Kirschner wire internal fixation, and ESIN. Curettage and bone grafting represent an efficient and reliable surgical method[5, 9, 13]. In cases where a UBC is adjacent to an epiphyseal plate and an unstable fracture is present, structural bone grafting using autologous fibula transplantation can mitigate the risk of bone graft collapse[12, 27]. Kirschner wire fixation enhances stability; thinner wires, when placed through the epiphyseal plate, do not interfere with normal growth in children. Removing the Kirschner wires 6-8 weeks post-surgery minimizes additional trauma. Currently, ESIN combined with bone grafting is considered the most effective treatment for UBCs, supported by numerous clinical reports[9, 28]. A critical consideration remains regarding the optimal timing for ESIN removal. Continuous drainage through the ESIN may positively influence UBC treatment; however, as bone grows, the external portion of the ESIN becomes encapsulated, complicating internal drainage and subsequent removal[6, 29]. The potential for UBC recurrence in young children following ESIN removal warrants further attention[8].\\u0026nbsp;While the possibility of recurrence exists with any treatment method, reducing Type 2 or Type 3 UBCs to Type 1 presents notable clinical significance.\\u003c/p\\u003e\\n\\u003cp\\u003eUBCs represent a unique clinical challenge, as the treatment-related trauma may outweigh the risks associated with the disease itself. Thus, effective management should take precedence over aggressive treatment[30]. It is essential to evaluate whether current treatment protocols are excessive and whether they confer tangible clinical benefits to patients. We believe that further research into UBCs will aid in minimizing unnecessary iatrogenic harm. A comprehensive understanding of UBC classification and treatment strategies will empower surgeons and patients in making informed clinical decisions.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eLimitations\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eOur study had several limitations. First, the statistical analysis revealed no significant differences between the various groups. This lack of distinction may be attributed to the retrospective nature of the clinical cases examined and potential biases stemming from previous interpretations. Second, there were disparities in the number of patients across different types, particularly for type 1 patients, who do not require treatment intervention and are typically monitored during outpatient follow-ups. Consequently, the data for hospitalized type 1 patients is limited. Third, the follow-up duration varied significantly, ranging from 24 to 144 months.\\u003c/p\\u003e\"},{\"header\":\"Conclusion\",\"content\":\"\\u003cp\\u003eIn conclusion, the clinical classification, tiered treatment strategies, and management of pediatric humeral UBCs hold significant clinical relevance.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAuthor Contributions\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eKZ and WW analyzed and interpreted the patient data regarding the treatment options. KZ put forward the research idea and participated in result interpretation and writing. KZ, WW, WX, MX, QC, and HC were involved in the development of research. KZ, WW, WX, and MX had designed and processed surgical technique. All authors performed the patients’\\u0026nbsp;treatments and KZ, MX, HC, and WW performed the patients’\\u0026nbsp;follow-up. All authors read and approved the final manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot applicable.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eData Availability Statement\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eEthics Statement\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eWe had prior ethics approval from Institutional Ethical Committee of The 960th Hospital of the PLA Joint Logistice Support Force (NO: 2018022) and adult patient consent was obtained for this study. The written informed consent was obtained from all subjects or their legal guardian. The research was carried out according to the principles set out in the Declaration of Helsinki 1964 and all subsequent revisions.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent to Participate declaration\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eInformed consent was obtained from the parents or legal guardians of all minor participants included in the study. Additionally, age-appropriate assent was also obtained from the children themselves whenever possible.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent for publication\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot Applicable.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eClinical trial number\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot Applicable.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCompeting interests\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare that they have no competing interests.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n \\u003cli\\u003eNoordin S, Allana S, Umer M, Jamil M, Hilal K, Uddin N. Unicameral bone cysts: Current concepts. Ann Med Surg. 2018;34 June:43\\u0026ndash;9.\\u003c/li\\u003e\\n \\u003cli\\u003ePretell-Mazzini J, Murphy RF, Kushare I, Dormans JP. Unicameral bone cysts: General characteristics and management controversies. J Am Acad Orthop Surg. 2014;22:295\\u0026ndash;303.\\u003c/li\\u003e\\n \\u003cli\\u003eKadhim M, Thacker M, Kadhim A, Holmes L. Treatment of unicameral bone cyst: Systematic review and meta analysis. J Child Orthop. 2014;8:171\\u0026ndash;91.\\u003c/li\\u003e\\n \\u003cli\\u003eUrakawa H, Tsukushi S, Hosono K, Sugiura H, Yamada K, Yamada Y, et al. Clinical factors affecting pathological fracture and healing of unicameral bone cysts. BMC Musculoskelet Disord. 2014;15:1\\u0026ndash;9.\\u003c/li\\u003e\\n \\u003cli\\u003eMavčič B, Saraph V, Gilg MM, Bergovec M, Brecelj J, Leithner A. Comparison of three surgical treatment options for unicameral bone cysts in humerus. J Pediatr Orthop Part B. 2019;28:51\\u0026ndash;6.\\u003c/li\\u003e\\n \\u003cli\\u003eZhang P, Zhu N, Du L, Zheng J, Hu S, Xu B. Treatment of simple bone cysts of the humerus by intramedullary nailing and steroid injection. BMC Musculoskelet Disord. 2020;21:1\\u0026ndash;11.\\u003c/li\\u003e\\n \\u003cli\\u003eToepfer A, Str\\u0026auml;ssle M, Lenze U, Lenze F, Harrasser N. Allogenic Cancellous Bone versus Injectable Bone Substitute for Endoscopic Treatment of Simple Bone Cyst and Intraosseous Lipoma of the Calcaneus and Is Intraosseous Lipoma a Developmental Stage of a Simple Bone Cyst? J Clin Med. 2023;12:4272.\\u003c/li\\u003e\\n \\u003cli\\u003eFarr S, Balac\\u0026oacute; IMS, Mart\\u0026iacute;nez-Alvarez S, Hahne J, Bae DS. Current Trends and Variations in the Treatment of Unicameral Bone Cysts of the Humerus: A Survey of EPOS and POSNA Members. J Pediatr Orthop. 2020;40:e68\\u0026ndash;76.\\u003c/li\\u003e\\n \\u003cli\\u003eRuiz-Arellanos K, Larios F, Inchaustegui ML, Gonzalez MR, Pretell-Mazzini J. Treatment and Outcomes of 4,973 Unicameral Bone Cysts: A Systematic Review and Meta-Analysis. JBJS Rev. 2024;12:1\\u0026ndash;13.\\u003c/li\\u003e\\n \\u003cli\\u003eZhang KX, Chai W, Zhao JJ, Deng JH, Peng Z, Chen JY. Comparison of three treatment methods for simple bone cyst in children. BMC Musculoskelet Disord. 2021;22:1\\u0026ndash;7.\\u003c/li\\u003e\\n \\u003cli\\u003eZhou J, Ning S, Su Y, Liu C. Elastic intramedullary nailing combined with methylprednisolone acetate injection for treatment of unicameral bone cysts in children: A retrospective study. J Child Orthop. 2021;15:55\\u0026ndash;62.\\u003c/li\\u003e\\n \\u003cli\\u003eJamshidi K, Bahradadi M, Bahrabadi M, Mirzaei A. Are Fibular Allograft Struts Useful for Unicameral Bone Cysts of the Proximal Humerus in Skeletally Mature Patients? Clin Orthop Relat Res. 2022;480:1181\\u0026ndash;8.\\u003c/li\\u003e\\n \\u003cli\\u003eBukva B, Vrgoč G, Abramović D, Dučić S, Brkić I, Čengić T. Treatment of Unicameral Bone Cysts in Children: a Comparative Study. Acta Clin Croat. 2019;58:403\\u0026ndash;9.\\u003c/li\\u003e\\n \\u003cli\\u003eLi J, Rai S, Ze R, Tang X, Liu R, Hong P. Injectable calcium sulfate vs mixed bone graft of autologous iliac bone and allogeneic bone: Which is the better bone graft material for unicameral bone cyst in humerus? Med (United States). 2020;99:1\\u0026ndash;4.\\u003c/li\\u003e\\n \\u003cli\\u003eD\\u0026rsquo;Amato RD, Memeo A, Fusini F, Panuccio E, Peretti G. Treatment of simple bone cyst with bone marrow concentrate and equine-derived demineralized bone matrix injection versus methylprednisolone acetate injections: A retrospective comparative study. Acta Orthop Traumatol Turc. 2020;54:49\\u0026ndash;58.\\u003c/li\\u003e\\n \\u003cli\\u003eSivakumar B, An VVG, Dobbe A, Drynan D, Little D. Injection of a Bone Substitute in the Treatment of Unicameral Bone Cysts. Adv Orthop. 2023;2023:3270372.\\u003c/li\\u003e\\n \\u003cli\\u003eLee SY, Chung CY, Lee KM, Sung KH, Won SH, Choi IH, et al. Determining the best treatment for simple bone cyst: A decision analysis. Clin Orthop Surg. 2014;6:62\\u0026ndash;71.\\u003c/li\\u003e\\n \\u003cli\\u003eKadhim M, Sethi S, Thacker MM. Unicameral bone cysts in the humerus: Treatment outcomes. J Pediatr Orthop. 2016;36:392\\u0026ndash;9.\\u003c/li\\u003e\\n \\u003cli\\u003eLiu Q, He H, Zeng H, Yuan Y, Wang Z, Tong X, et al. Active unicameral bone cysts: Control firstly, cure secondly. J Orthop Surg Res. 2019;14:1\\u0026ndash;9.\\u003c/li\\u003e\\n \\u003cli\\u003eTey IK, Mahadev A, Lim KBL, Lee EH, Nathan SS. Active unicameral bone cysts in the upper limb are at greater risk of fracture. J Orthop Surg (Hong Kong). 2009;17:157\\u0026ndash;60.\\u003c/li\\u003e\\n \\u003cli\\u003eScaglietti O, Marchetti PG, Bartolozzi P. Final results obtained in the treatment of bone cysts with methylprednisolone acetate (depo-medrol) and a discussion of results achieved in other bone lesions. Clin Orthop Relat Res. 1982;:33\\u0026ndash;42.\\u003c/li\\u003e\\n \\u003cli\\u003eChang CH, Stanton RP, Glutting J. Unicameral bone cysts treated by injection of bone marrow or methylprednisolone. J Bone Jt Surg - Ser B. 2002;84:407\\u0026ndash;12.\\u003c/li\\u003e\\n \\u003cli\\u003eChigira M, Maehara S, Arita S, Udagawa E. The aetiology and treatment of simple bone cysts. J Bone Joint Surg Br. 1983;65:633\\u0026ndash;7.\\u003c/li\\u003e\\n \\u003cli\\u003eBezirgan U, Karaca MO, Merter A, Ercan N, Basarir K, Erg\\u0026uuml;n H, et al. Steroid Injection and Biomarker Levels in the Treatment of Unicameral Bone Cysts: Can we Estimate the Result? Indian J Orthop. 2021;55:886\\u0026ndash;91.\\u003c/li\\u003e\\n \\u003cli\\u003ePogorelić Z, Kadić S, Milunović KP, Pintarić I, Jukić M, Furlan D. Flexible intramedullary nailing for treatment of proximal humeral and humeral shaft fractures in children: A retrospective series of 118 cases. Orthop Traumatol Surg Res. 2017;103:765\\u0026ndash;70.\\u003c/li\\u003e\\n \\u003cli\\u003ePaez CJ, Grant K, Bomar JD, Edmonds EW. Outcomes in Unicameral Bone Cyst Management Utilizing a Decision Tree Algorithm Approach: UBC Decision Tree. Z Orthop Unfall. 2022;160:400\\u0026ndash;6.\\u003c/li\\u003e\\n \\u003cli\\u003eJamshidi K, Mirkazemi M, Izanloo A, Mirzaei A. Locking plate and fibular strut-graft augmentation in the reconstruction of unicameral bone cyst of proximal femur in the paediatric population. Int Orthop. 2018;42:169\\u0026ndash;74.\\u003c/li\\u003e\\n \\u003cli\\u003eXie Y, Song Z, Tang Z, Xu Z, Rao Z, Wen J, et al. Percutaneous calcium sulfate injection versus localized scrape bone grafting: clinical effect comparison in titanium elastic nail treatment of pathological fracture of proximal humerus caused by unicameral bone cysts in children. Front Pediatr. 2024;11:1334950.\\u003c/li\\u003e\\n \\u003cli\\u003eLiu J, Su Y. Factors which can influence elastic stable intramedullary nailing removal in healed bone cysts in children. Sci Rep. 2024;14:1\\u0026ndash;7.\\u003c/li\\u003e\\n \\u003cli\\u003evan Geloven TPG, van der Heijden L, Laitinen MK, Campanacci DA, D\\u0026ouml;ring K, Dammerer D, et al. As simple as it sounds? The treatment of simple bone cysts in the proximal femur in children and adolescents: Retrospective multicenter EPOS study of 74 patients. J Child Orthop. 2024;18:85\\u0026ndash;95.\\u003cstrong\\u003e\\u003cbr\\u003e\\u003c/strong\\u003e\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"},{\"header\":\"Table\",\"content\":\"\\u003cp\\u003eTable 1 demographic data for patients with UBCs\\u003c/p\\u003e\\n\\u003ctable border=\\\"1\\\" cellspacing=\\\"0\\\" cellpadding=\\\"0\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003eConsistent\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eInconsistent\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003ep\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eGender\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e0.687\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eMale\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e15\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e11\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eFemale\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e4\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eAge, years (SD)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e9.8\\u0026plusmn;2.9\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e9.1\\u0026plusmn;3.4\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e0.526\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eClinical classification\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e0.054\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eType 1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eType 2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e7\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e10\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eType 3\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e11\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eTreatment\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e0.122\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eWatch and wait\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e0\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eMPA injection\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e7\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e3\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;Curettage\\u003c/p\\u003e\\n \\u003cp\\u003e+ bone graft\\u003c/p\\u003e\\n \\u003cp\\u003e\\u0026plusmn; internal fixation\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e4\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e8\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eESIN\\u003c/p\\u003e\\n \\u003cp\\u003e+ curettage\\u003c/p\\u003e\\n \\u003cp\\u003e+ bone graft\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e7\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eFollow-up, months (SD)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e64.9 \\u0026plusmn; 36.5\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e85.3 \\u0026plusmn; 44.9\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e0.232\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eCurative effect\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e0.129\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eHealed\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e10\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e6\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003eHealed with defects\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e8\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e3\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003ePersistent cyst\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 25.6781%;\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 27.3056%;\\\"\\u003e\\n \\u003cp\\u003e4\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd valign=\\\"top\\\" style=\\\"width: 19.7107%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Clinical classification, Management strategy, Unicameral bone cyst, Children, Humerus\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-7767054/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-7767054/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003e\\u003cstrong\\u003eObjective: \\u003c/strong\\u003eThis study aims to describe and assess the clinical classification and management strategies for humeral unicameral bone cysts (UBCs) in children.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eMethods: \\u003c/strong\\u003eThe classification and management strategy for pediatric humeral UBCs was developed based on a review of existing literature and an evaluation of our clinical practice. A retrospective analysis of pediatric patients with humeral UBCs was conducted to preliminarily validate the proposed classification and treatment strategies. Clinical efficacy was categorized into three levels: healed, healed with defects, and persistent cyst.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eResults:\\u003c/strong\\u003e Pediatric humeral UBCs were classified into three clinical types, each with two subtypes. Type 1 represents stable UBCs, for which a conservative “wait and see” approach is recommended. Type 2 indicates invasion and destruction of bone by UBCs, with or without stable pathological fractures. The treatment plan for Type 2 includes preferential treatment with methylprednisolone acetate (MPA) injection therapy, with surgical intervention if MPA is ineffective. Type 3 involves unstable pathological fractures caused by UBCs, for which fracture reduction, cyst curettage, bone grafting, and fixation with an elastic stable intramedullary nail (ESIN) or Kirschner wire are recommended. We followed up with 32 patients for an average of 73.2 months (range, 24–144 months). The cohort included six females and twenty-six males, with ages at presentation ranging from 3 to 14 years (mean age, 9.5 years). Nineteen patients met the classification treatment protocol, while the remaining thirteen did not. In the matching group, there was one case of Type 1, seven cases of Type 2, and eleven cases of Type 3. In the non-matching group, among the ten Type 2 patients, eight did not receive MPA injection therapy and instead underwent major surgeries, including seven cases of curettage and bone grafting and one case necessitating ESIN. The other two Type 2 patients did not receive ESIN treatment following inadequate response to MPA injection. Two Type 3 patients received MPA injection treatment, while one underwent external fixation and the other underwent curettage and bone grafting. In the matching group, ten patients achieved complete healing, eight experienced healing with defects, and one had a recurrence of UBC. In the non-matching group, six patients healed, three healed with defects, and four had recurrences. Despite numerical differences, statistical analysis did not reveal significant differences between the groups.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConclusion: \\u003c/strong\\u003eThe clinical classification and management strategies for humeral UBCs in children are validated by this study. The findings provide important references in clinical decision-making.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Clinical classification and management strategy for humeral unicameral bone cyst in children\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2025-11-21 17:50:21\",\"doi\":\"10.21203/rs.3.rs-7767054/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"714f0f5e-c4ef-4858-beb7-c6c4a74087e6\",\"owner\":[],\"postedDate\":\"November 21st, 2025\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2026-02-05T06:11:49+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2025-11-21 17:50:21\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-7767054\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-7767054\",\"identity\":\"rs-7767054\",\"version\":[\"v1\"]},\"buildId\":\"8U1c8b4HqxoKbykW_rLl7\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}