Mobile-bearing medial unicompartmental knee arthroplasty restores limb alignment comparable to that of the unaffected contralateral limb

Abstract

Background and purpose — Medial unicompartmental knee arthroplasty (UKA) is undertaken in patients with a passively correctable varus deformity. We investigated whether restoration of natural soft tissue tension would result in a lower limb alignment similar to that of the contralateral unaffected lower limb after mobile-bearing medial UKA.Patients and methods — In this retrospective study, hip-knee-ankle (HKA) angle, position of the weight-bearing axis (WBA), and knee joint line obliquity (KJLO) after mobile-bearing medial UKA was compared with that of the unaffected (clinically and radiologically) contralateral lower limb in 123 patients.Results — Postoperatively, HKA angle was restored to within ±3° of the contralateral lower limb in 87% of the patients and the WBA passed within ±1 Kennedy and White’s tibial zone of the unaffected contralateral lower limb in 95% of the patients. The mean KJLO in the operated limbs was not significantly different from that in the unaffected lower limbs (p = 0.07) and the KJLO in the operated limb was restored to within ±3° of that in the contralateral lower limb in 96% of the patients.Interpretation — Lower limb alignment and knee joint line obliquity after mobile-bearing medial UKA were comparable to that of the unaffected contralateral limb in most patients. Comparison with the contralateral unaffected lower limb is a reliable method for evaluation and validation of limb mechanical alignment after mobile-bearing medial UKA.

A Comparison of Mobile- and Fixed-Bearing Unicompartmental Knee Arthroplasties in the Treatment of Medial Knee Osteoarthritis: A Systematic Review and Meta-analysis of 1,861 Patients

“…Many authors have reported that the MB design has a theoretical advantage over the FB design and offers better restoration of natural kinematics of the knee. [31][32][33] Some other studies have shown similar functional outcomes and ROM of the MB and FB designs. 14,30 Our meta-analysis Abbreviation: RCT, randomized controlled trial.…”

Unicompartmental knee arthroplasty, an enigma, and the ten enigmas of medial UKA

“…2) and in the surgical techniques required for their implantation. The MB is designed to allow more natural joint kinematics [98,99], while also allowing a higher degree of conformity between the articular surfaces. Its distinctive design is proposed to reduce the surface and subsurface contact stresses granting less likelihood of polyethylene wear compared with FB designs [100,101].…”

Outcomes Following Revision Surgery After Failed Kidner Procedure for Painful Accessory Navicular

“…In orthopedics, alignment of the contralateral side is often referenced to help establish a surgical plan and parameters for evaluating radiographic correction. 3,7,24,32,34 Our hypothesis was based on the principle that both feet were symmetrically aligned before the Kidner procedure. Radiographically, both sides had similar deformity, with 14 patients (67%) having identical alignment.…”