Lateral unicompartmental knee arthroplasty is an effective procedure for lateral post-meniscectomy knee osteoarthritis: a case-control study at a mean 7-year follow-up.

BACKGROUND

Meniscectomy is a common knee surgery for meniscal tear, and is associated with progressive osteoarthritis (OA). There are few literatures focus on the use of lateral unicompartmental knee arthroplasty (UKA) for lateral post-meniscectomy knee osteoarthritis (PMKO). Therefore, the purpose of this study is to compare the outcomes of lateral UKA performed for lateral PMKO and primary lateral compartment knee osteoarthritis (LCKO).

METHODS

A total of 38 consecutive patients (38 knees) who received lateral UKAs for isolated lateral PMKO between September 2013 and September 2019 were retrospectively analyzed. Other thirty-eight patients (38 knees) with primary LCKO were allocated into control group by 1:1 matching according to age, gender, and body mass index. The clinical outcomes were evaluated using the American Knee Society Score, range of motion, Forgotten Joint Score, and EuroQol-5D (EQ-5D) Score. The radiographic assessments included hip-knee-ankle (HKA) angle, mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), and posterior tibial slope angle (PTSA).

RESULTS

With a mean 7 years follow-up, there was no significant difference in functional and radiographic outcomes between groups. However, the PMKO group showed severe lateral OA (p = 0.02) preoperatively and less OA progression in the medial compartment postoperatively (p = 0.046). The preoperative mLDFA was significantly more valgus in the LCKO group (p < 0.001). No case of revision occurred in either group.

CONCLUSION

Lateral UKA is a valid procedure for lateral PMKO. The clinical and radiographic results are similar in patients underwent lateral UKA for lateral PMKO and for LCKO. Patients with lateral PMKO exhibited severe lateral OA preoperatively and less OA progression in the medial compartment compared to those with LCKO. It is crucial to prevent ascension of the lateral femoral joint-line and maintain proper valgus alignment during lateral UKA.