Abstract
Total knee arthroplasty (TKA) for patients with valgus deformity (> 10 degrees) is
technically challenging and has produced variable clinical results in terms of deformity
correction, instability, and overall outcomes. The lateral parapatellar approach (LPA)
is an alternative to the traditional medial parapatellar approach with potential advantages
of direct access for release of tight lateral ligamentous structures with preservation
of the medial structures, optimized patellar tracking, preserved medial blood supply
to the patella, and less use of constrained implants. We present a case series of
a single institution's experience with use of a modified LPA using a Z-capsuloplasty
for 35 primary TKA cases in 30 patients with osteoarthritis and Ranawat's type-II
fixed valgus deformity with attenuation of medial soft tissues. The mean age of patients
was 64.8 years (range: 42–78 years). Follow-up duration was a mean of 47.3 months
(range: 3–130 months). The patients were assessed pre- and postoperatively using radiographic
measurement of the anatomic femorotibial angle (FTA) and clinical measurement of range
of motion (ROM) and the Chinese knee society score (KSS). Complications and reoperations
were recorded. The mean coronal alignment was corrected from 20.4 degrees of valgus
(range: 11.3–42 degrees) preoperatively to 7.0 degrees of valgus (range: 3.6–15.1
degrees) postoperatively. One case required use of a constrained condylar design implant.
At a mean of 47.3 months, the mean Knee Society objective and functional scores improved
to 91.8 ± 6.6 and 84.3 ± 18.2 points, respectively. Mean ROM was 94.9 degrees preoperatively
and 105.7 degrees postoperatively. Three cases (8.6%) had postoperative complications,
including transient common peroneal nerve palsy, hematoma, and deep infection. One
patient underwent two-stage revision for infection. There were no cases of late instability.
The modified LPA using a Z-capsuloplasty is a reproducible and effective surgical
technique for performing TKA in the setting of osteoarthritis and severe valgus deformity.
Keywords
lateral parapatellar approach - TKA - valgus knee
