Treatment Strategies and Clinical Outcomes of Knee Osteoarthritis With Extra-Articular Deformity

Abstract ObjectiveTo evaluate the methods, indications, and efficacy of the treatment of knee osteoarthritis with extra-articular deformity. MethodsA retrospective study of eight patients (three males and five females) with knee osteoarthritis complicated with extra-articular femoral deformity from February 2011 to April 2019; with an average age of 62.9 years (range 57 to 70 years). There were eight cases of coronal malformation with a mean angle of 15.5° (range 5° to 24°), and three cases of sagittal deformity with a mean angle of 14.0° (range12–16°). All eight patients underwent total knee arthroplasty (TKA). Three patients underwent femoral osteotomy and one-stage total knee arthroplasty, and one underwent femoral osteotomy and second-stage total knee joint replacement. ResultsThe mean follow-up time was 45.6 months (range 2 to 96 months). The average HSS score improved from 41.1 points (range, 28–53) preoperatively to 88.5 points (range, 71–95) at the time of the last follow-up. The average VAS score improved from 6.6 points (range, 3–10) preoperatively to 0.3 points (range, 0–1) at the time of the last follow-up. The average arc of knee motion improved from 66.3° (range 50° to 85°), preoperatively to 104.4°(range 95° to 120°) postoperatively. The average deviation of the mechanical axis of the knee improved from 17.3° (range 13° to 20°) preoperatively to 2.6°(range -6° to 6°) postoperatively. The differences between the preoperative data and postoperative follow-up data were statistically significant (P < 0.05). At the last follow-up visit, none of the eight patients had postoperative complications such as prosthesis loosening, infection, or deep vein thrombosis of the lower limbs. No bone nonunion, delayed union, or other complications occurred in the four patients with osteotomy. ConclusionAlthough it is difficult and complex to perform TKA surgery in patients with extra-articular deformity, a preoperative surgical plan should be made individually according to the patient's condition, and if necessary, the mechanical axis of the lower limbs can be effectively restored with the help of computer navigation technology or 3D printing technology, to achieve satisfactory surgical results.