Cementless total hip arthroplasty for treatment of acetabular protrusion secondary to rheumatoid arthritis

Background: To explore the surgical technique and clinical outcomes of cementless total hip arthroplasty (THA) combined with impacted bone grafting in treating moderate and severe acetabular protrusion with rheumatoid arthritis (RA). Methods: : From January 2010 to October 2020, 45 patients (56 hips) with RA secondary to acetabular invagination were treated with biological prosthesis THA combined with autologous bone grafting in our hospital, including 17 males (22 hips) and 28 females (34 hips). According to Sotello-Garza and Charnley classification criterion, there were 40 cases（49 hips）of typeⅡ(protrusio acetabuli 6-15 mm), and 5 cases（7 hips）of type Ⅲ (protrusio acetabuli ＞15 mm). At the postoperative follow-up, the ROM of the hip joint, the VAS score, and the Harris score were evaluated. The healing of the bone graft, the restoration of the hip rotation center, and the prosthesis loosening were assessed by plain anteroposterior radiographs. Results: : The average operation time was 95.53 ± 22.45 min, and the mean blood loss was 156.16 ± 69.25 mL. There were no neurovascular complications during the operation. The mean follow-up duration was 5.20 ± 1.20 years. The horizontal distance of the hip rotation center was increased from preoperative 10.40 ± 2.50 mm to postoperative 24.03 ± 1.77 mm, and the vertical distance was increased from preoperative 72.36 ± 3.10 mm to postoperative 92.48±5.31 mm. The range of flexion motion of the hip joint increased from 39.48 ± 8.36° preoperatively to 103.07 ± 7.64° postoperatively, and the range of abduction motion increased from 10.86 ± 4.34° preoperatively to 36.75 ± 3.99° postoperatively. At the last follow-up, the Harris score increased from 37.84 ± 4.74 to 89.55 ± 4.05. All the patients could move independently without assistance. Conclusions: : Cementless THA combined with impacted grafting granule bone of the autogenous femoral head and biological acetabular cup can reconstruct the acetabulum, restore the rotation center of the hip joint, and achieve good medium-term outcomes in the treatment of moderate and severe acetabular protrusion secondary to RA.