Original article
The Use of Computer-Assisted Surgical Navigation to Prevent Malalignment in Unicompartmental Knee Arthroplasty

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Abstract

We reviewed the outcome of 30 consecutive primary unicompartmental knee arthroplasties (UKAs) performed by a single surgeon over a 26-month period. All operations were performed to treat osteoarthritis of the medial compartment of the knee. Fifteen Allegretto (Sulzer, Winterthur, Switzerland) UKAs were implanted without computer navigation whereas 15 EIUS (Stryker-Howmedica, Allendale, NJ) UKAs were implanted using navigation. The patients were assessed clinically using the Oxford knee score and radiologically using long-leg weight-bearing films and non–weight-bearing computed tomography leg alignment films. No patients operated on were lost to follow-up. Unicompartmental knee arthroplasty performed with computer-assisted surgical navigation resulted in a more accurate and reproducible limb alignment than UKA performed without surgical navigation.

Section snippets

Patients and Methods

Between May 2001 and August 2003, 30 consecutive primary medial compartment UKAs were performed by the senior author (AJS). Of this group, 15 had an un-navigated Allegretto (Sulzer) UKA whereas 15 had a navigated EIUS (Stryker-Howmedica) UKA. Strict selection criteria had to be met in order for the operation to proceed (Table 2). The final decision as to whether to proceed to unicompartmental or TKA was made at the time of surgery when the chondral surfaces could be assessed visually.

Operation Technique

All the operations were performed under prophylactic antibiotic cover with the use of a tourniquet. The approach to the medial compartment was through a limited medial parapatellar incision with an average length of 7.5 cm with no patellar dislocation. The Allegretto UKA relied on conventional extramedullary instrumentation to achieve correct alignment. The EIUS unicompartmental knee used a computer navigation system to act as an adjunct intraoperatively to measure intraoperative alignment.

The

Allegretto Group

This group consisted of 10 women and 4 men, one of the men having bilateral arthroplasties. No patients were lost to follow-up. Their mean age at the time of surgery was 57 years (range, 42-74 years). The mean tourniquet time was 58 minutes. The mean follow-up was 17 months (range, 15-23 months). The mean Oxford knee score was 18 (range, 15-23). Postoperative complications included 1 deep venous thrombosis above the knee, which was treated with warfarin, and 1 superficial wound infection. The

Discussion

Unicompartmental knee arthroplasty has been part of the orthopedic surgeons armamentarium for the treatment of unicompartmental OA for the past 30 years. Over recent years the orthopedic literature has shown excellent mid-term to long-term results in both fixed-bearing and mobile-bearing UKAs performed for medial compartment joint disease 5., 6., 7., 8., 9., 10., 11., 12., 13., 14.. With such encouraging results the potential for more orthopedic surgeons to perform this technically challenging

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