Comparison of radiological and functional outcomes between kinematically aligned and contralateral mechanically aligned total knee arthroplasty.

BACKGROUND

This comparative study aims to evaluate soft tissue releases, radiological, and functional outcomes between kinematically aligned total knee arthroplasty (KA-TKA) in one knee and mechanically aligned total knee arthroplasty (MA-TKA) in the contralateral extremity.

METHODS

In 37 patients with osteoarthritis, one knee was treated with KA-TKA, whereas the opposite knee had received MA-TKA approximately 29.6 ± 2.3 months prior.

RESULTS

Soft tissue releases, radiological parameters such as hip-knee-ankle angle (HKA), medial distal femoral angle (mDFA), medial proximal tibial angle (mPTA), knee joint line obliquity (KJLO) and functional outcomes including Knee Society Score (KSS), Knee Society Functional Score (KSFS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), High Flexion Knee Score (HFKS), Visual Analogue Scale (VAS) and Forgotten Joint Score (FJS-12) were measured and compared between the two sides. KA-TKA showed improvement in some functional scores such as KSFS, WOMAC, VAS, FJS-12 compared to MA-TKA, but improvements did not exceed the Minimum Clinically Important Difference (MCID). Overall 30 of 37 patients (81.1%) experienced less post-operative pain and walking difficulty with KA-TKA, 19 patients (51.4%) found the kinematically aligned knee felt more natural, and 22 patients (59.6%) would recommend kinematically aligned total knee arthroplasty to others.

CONCLUSIONS

Kinematically aligned total knee arthroplasty required significantly fewer overall soft tissue releases including no MCL pie-crusting and less semimembranosus release (overall value p = 0.02) when compared to contralateral mechanical alignment, possibly leading to modest improvements in selected patient-reported outcomes and satisfaction rate.

LEVEL OF EVIDENCE: III.