Clin Orthop Surg.  2011 Sep;3(3):178-183. 10.4055/cios.2011.3.3.178.

Mid-Term Results of Oxford Medial Unicompartmental Knee Arthroplasty

• Choy WS
• Kim KJ
• Lee SK
• Yang DS
• Lee NK

• KMID: 1743907
• DOI: http://doi.org/10.4055/cios.2011.3.3.178

Abstract

BACKGROUND
This study examined the clinical and radiologic mid-term results of patients treated by Oxford minimally invasive unicompartmental knee arthroplasty.
METHODS
One hundred and eighty-eight knees of unicompartmental knee arthroplasties with Oxford Uni(R) in 166 patients (16 males and 150 females), which were performed between 2002 and 2005, were reviewed. The mean age was 65.3 years (range, 44 to 82 years) and the mean follow-up period was 79.8 months (range, 56 to 103 months). The preoperative diagnosis was osteoarthritis in 166 patients, osteonecrosis of the medial femoral condyle in 20 and chondrocalcinosis in 2.
RESULTS
The mean Hospital for Special Surgery (HSS) knee score was 67.5 (range, 52 to 75) preoperatively and 89.9 (range, 85 to 100) at the final follow-up. The mean preoperative flexion contracture was 6.5degrees (range, 0 to 15degrees) and 0.8degrees (range, 0 to 5degrees) at the final follow-up. The mean full flexion increased from 135degrees (range, 90 to 150degrees) preoperatively to 150degrees (range, 140 to 165degrees) at the final follow-up. Active full flexion was possible within 2 postoperative months. The squatting and cross-leg postures were possible in 133 patients (80.1%) and 152 patients (91.6%) at the final follow-up. The mean tibiofemoral angle was improved from varus 1.5degrees to valgus 4.8degrees. Complications were encountered in 18 cases (9.5%). A bearing dislocation occurred in 10 cases (5.3%), tibial component loosening in 4 cases (2.1%), femoral loosening in 3 cases (1.6%) and lateral translation in 1 case (0.5%). The mean time for a bearing dislocation was 22.6 months (range, 3 to 70 months) postoperatively. Seven cases returned to the predislocation level of activity with the insertion of a thicker bearing and 3 cases converted to total knee arthroplasty.
CONCLUSIONS
Minimally invasive unicompartmental knee arthroplasty with Oxford Uni(R) provided rapid recovery, good pain relief and excellent function suitable for the Korean lifestyle. In contrast, the high complication rates of Oxford Uni(R) encountered in the mid-term results suggested less reliability than total knee arthroplasty.

Keyword

Knee; Unicompartmental knee arthroplasty

MeSH Terms

Adult
Aged
Aged, 80 and over
*Arthroplasty, Replacement, Knee/adverse effects
Female
Humans
Knee Joint/physiopathology/radiography
*Knee Prosthesis
Male
Middle Aged
Prosthesis Failure
Range of Motion, Articular

Figure

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  Fig. 1 Cumulative rate of survival of the prosthesis was 89.9% at 6.6 years (95% confidence interval).

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  Fig. 2 The meniscal bearing moves posteriorly as the knee is flexed fully.

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  Fig. 3 Dislocated bearing with deformed reduced posterior lip of an anatomic bearing.

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