Clinical outcomes of primary total knee arthroplasty in non-syphilitic neuroarthropathy of the knee

Purpose Total knee arthroplasty (TKA) in syphilitic neuroarthropathy using earlier implant designs was associated with poorer outcomes. Literature on TKA for non-syphilitic neuroarthropathy using modern contemporary prosthesis is scarce. We aim to analyse the clinical and radiological outcomes of TKA in neuropathic joints. Methods A final cohort of 17 patients (21 knees) with the diagnosis of neuropathic joint undergoing primary TKA between January 2013 to January 2019 were included in the study. The preoperative ambulatory status, range of motion, type of prosthesis, level of constraint and any augmentation used were retrieved from medical records. Radiological evaluation includes Koshino's staging, the magnitude of deformity defined by the Hip-Knee-Ankle (HKA) angle, and any progressive loosening. Pre and postoperative functional scores were obtained by the Knee Society (KSS) and Knee Society Functional Score (KSS-F). Any complications or reoperation were noted till the final follow-up. Preoperative and follow-up functional scores, HKA and range of motion were compared using the paired Samples test. Results The mean follow-up was 40.2 months (range, 15 to 75 months). Preoperatively, according to the Koshino staging, five knees were in stage 3 (23.8%). The mean HKA angle in valgus knees was 23.6(0) (range, 11.1(0) to 42.5(0)) and for the varus knees was 19.3(0) (range, 4.9(0) to 39.6(0)). The prosthesis used were posterior stabilized in 7 knees (33.3%), varus-valgus constrained in five knees (23.8%) and a rotating hinge was required in nine knees (42.8%). Metaphyseal sleeves were used along with hinge prosthesis in six knees (28.6%). The mean arc of motion improved from 102.4 +/- 22.7 degrees to 105.7 +/- 15.5 degrees postoperatively (p = 0.27). The knee society and knee society functional scores improved from 23.3 +/- 9.3 and 28.3 +/- 12.2 preoperatively to 81.1 +/- 5.4 and 80.4 +/- 8.5 during the follow up respectively (p < 0.001). There were no progressive radiolucent lines in any knees at the final follow-up. One patient had intraoperative bony medial collateral ligament injury, one patient had deep vein thrombosis after five days from the index surgery and another had postoperative periprosthetic tibial shaft fracture. Conclusion According to our study, the clinical outcomes of TKA for neuroarthropathy show significant improvement with the diagnosis of non-syphilitic neuroarthropathy, utilization of modern constrained prostheses, and early rehabilitation, at medium-term follow-up. Tibial and femoral stems are preferred for equal stress distribution and to prevent early loosening.