CAN A CHANGE IN IMPLANT ARTICULAR GEOMETRY AFFECT POSTOPERATIVE RANGE OF MOVEMENT IN PATIENTS UNDERGOING PRIMARY TKA FOR OSTEOARTHRITIS?

Abstract

To evaluate the effect of implant articular geometry on postoperative range of motion (ROM) after primary total knee arthroplasty for osteoarthritis, we conducted a retrospective case-control study of one hundred and twenty patients (sixty in each group) comparing Scorpio® Posterior Cruciate Substituting implant using Superflex® versus traditional tibial insert. Cases and controls were matched 1:1 for surgeon and gender. Both groups had similar baseline characteristics. Except for KSS Clinical Score at six months (mean: 92.8 for Superflex® versus 87.6 for traditional insert; p=0.029), there was no statistically significant difference between the two groups in knee scores or ROM up to one-year postoperatively.

To evaluate the effect of implant articular geometry on postoperative range of motion (ROM) after primary TKA.

Despite the advent of high flexion knee designs, surgical technique and patient driven factors remain the overriding determining factors for ultimate flexion range achieved following TKA.

One hundred and twenty patients (sixty in each group) were included. Both groups had similar baseline characteristics. Except for KSS Clinical Score at 6 month (mean ± SD: 92.8 ± 5.8 for Superflex® versus 87.6 ± 14.6 for traditional insert; p=0.029), there was no statistically significant difference between the two groups in knee scores or ROM. Flexion at one year for Superflex® was 113.5° ± 10.5 compared with 113.2° ± 11.9 for traditional tibial insert (p=0.869).

Retrospective cohort study of a prospectively gathered database of TKA’s performed at a high-volume arthroplasty center from 1998 to 2003. Inclusion Criteria: primary TKA for osteoarthritis using Scorpio® Posterior Cruciate Substituting implant with Superflex® tibial insert versus traditional insert. Exclusion Criteria: WSIB, prior history of septic arthritis, and previous knee surgery. Cases and controls were matched 1:1 for surgeon and gender. Postoperative care was standardized. Data points included demographics, operative details, pre- and post-operative Knee Society Score (KSS), Oxford Knee Score and range of motion at six weeks, six months and one year postoperatively. P< 0.05 was considered statistically significant.

Despite improvements in knee prostheses design, patient factors and surgical technique remain the most important determinants of outcome in primary TKA, particularly ROM.