‘Right-Angled Anteromedial Knee Arthrotomy’ in Total Knee Arthroplasty: A Novel Surgical technique and Retrospective short-term cohort study in consecutive patients

Background: An adequate knee arthrotomy providing visualization is critical for implanting a well-aligned total knee arthroplasty. This paper describes a novel technique of ‘Right-Angled Anteromedial Knee Arthrotomy’ that allows excellent exposure of routine and even of some stiff knees, while enabling precise closure, thus avoiding problems seen with improper tensioning of the extensor mechanism. Purpose: The purpose of this study was to answer the following questions: 1) What is the incidence of extensor mechanism complications after the described technique 2) Is it possible to achieve range of motion to or beyond 120 0 ? 3) What is the incidence of significant (10 deg or more) extensor lag after this technique? Methods: The ‘Right-Angled Anteromedial Knee Arthrotomy’ was used to perform Total Knee Arthroplasty in 78 consecutive patients (85 knees). Range-of-motion measurements and complications were recorded. Data collected as part of routine clinical follow-up was analyzed retrospectively. Independent Institutional Review Board (Ethics Committee) exemption was obtained for publication. Results: Average and median follow up for the cohort was 48.1 and 40 weeks, respectively. During the follow-up period, there were zero instances of quadriceps tendon rupture and no re-operations for extensor mechanism complications. Three patients (3/85 = 3.5%) had an extensor lag of 10–15 degrees. The maximum range-of-motion achieved in any patient in the cohort was 140 degrees, while the minimum was 95 degrees. Six knees (6/85 = 7%) had a residual flexion contracture, from 5 to 15 degrees. All patients reported improved clinically, returning to or exceeding pre-operative activity, including stair climbing. Conclusions: The ‘Right-Angled Anteromedial Knee Arthotomy’ as described was a viable technique for primary and revision total knee arthroplasty in this group of patients with good short term results. There were no complications that were attributable to the approach, especially in the time frame relevant to the integrity of the healing of the extensor mechanism.