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UniSpacer arthroplasty of the knee

Los Angeles Orthopaedic Institute, 4955 Van Nuys Boulevard, Suite 615, Sherman Oaks, California 91403, USA.
The Journal of Bone and Joint Surgery (Impact Factor: 4.31). 09/2005; 87(8):1706-11. DOI: 10.2106/JBJS.D.02339
Source: PubMed

ABSTRACT The operative treatment of medial compartment knee arthritis is controversial. The purpose of the present study was to report the experience of a single surgeon with the UniSpacer arthroplasty for the treatment of isolated medial compartment arthritis of the knee.
From April 2002 through November 2002, thirty-seven UniSpacer arthroplasties were performed in thirty-four patients for the treatment of arthritis that primarily involved the medial compartment of the knee. The Ahlbäck radiographic evaluation scale was used to grade the severity of arthritis; the mean preoperative score was 2.6 points for the medial compartment and 0.5 point for both the lateral and patellofemoral compartments. The study group included eighteen women (nineteen knees) and sixteen men (eighteen knees) who had a mean age of fifty-five years (range, forty-two to seventy-five years) at the time of surgery. Twelve patients had had a previous arthroscopic meniscectomy. The mean preoperative Knee Society function score was 60 points (range, 40 to 80 points), and the mean preoperative Knee Society objective score was 62 points (range, 40 to 76 points).
After a mean duration of follow-up of twenty-six months (range, twenty-four to twenty-nine months), there were no excellent, ten good, fifteen fair, and twelve poor results. The mean postoperative total function score was 69 points (range, 40 to 82 points), and the mean Knee Society objective score was 72 points (range, 45 to 88 points). Six of the twelve poor results were in knees that had dislocation of the UniSpacer. All twelve knees were revised to a total knee arthroplasty.
On the basis of this experience, we do not recommend UniSpacer arthroplasty for the treatment of degenerative arthritis of the medial compartment of the knee.

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    • "Use of the UniSpacer™ in unicompartmental OA was initially recommended for young and active patients (Hallock & Fell, 2003). The role of this procedure still is not certain as it has been considered suitable for only few patients (1%) (Scott & Deshmukh, 2005) and there have been reports of poor postoperative results due to implant dislocation (up to 44%) (Bailie et al., 2005; Sisto & Mitchell, 2005). Clarius et al. showed in their study a significant, slightly over-adjusting, correction of moderate varus alignment by UniSpacer™ arthroplasty, which does not correlate with the thickness of the implant used (Clarius et al., 2003). "
    Recent Advances in Hip and Knee Arthroplasty, 01/2012; , ISBN: 978-953-307-841-0
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    • "In the literature, the evaluation of the performance of interpositional spacers is based on post-operative clinical data, where knee rating systems have been used for the evaluation of knee pain, stability, range of motion and patient's ability to carry out daily activities after surgery. Major problems such as implant dislocation, pain and need for revision have been reported (Hallock and Fell, 2003; Sisto and Mitchell, 2005). Factors such as patient selection, surgical procedure and implant design have been deemed important for positive clinical outcomes, but the exact causes of these problems remain unknown. "
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    ABSTRACT: Interpositional arthroplasty is considered by many surgeons for the treatment of isolated medial compartment osteoarthritis of the knee. In this procedure, an interpositional spacer is inserted into the medial compartment of the joint with no bone resection and no mechanical fixation. Major problems such as implant dislocation, severe pain or need for revision have been reported post-operatively. In this study, the kinematics of a knee implanted with an interpositional spacer made of either polyurethane or cobalt-chrome during walking, stair ascent and squatting cycles have been predicted and compared to the normal knee using finite element analysis. In addition, articular cartilage stress histories have been examined to obtain distributions of cumulative stress, a measure of the likelihood of articular cartilage degeneration. The insertion of a polyurethane interpositional spacer in the medial side of the knee did not affect knee kinematics as compared to the normal knee, but caused an increase of articular cartilage cumulative contact stress exposures in the medial compartment of the joint. The knee implanted with the Co-Cr spacer exhibited similar trends in knee kinematics, however significantly different ranges of motion were observed during some periods of the activity cycles, specifically during the first half of the walking cycle where lower ranges of motion were predicted. In addition, higher articular cartilage cumulative contact stress exposures were observed in both compartments of the knee. In both cases, cumulative contact stress exposures of the tibial articular cartilage were more affected than those of the femoral articular cartilage. These results suggest implant material as an important parameter in the design phase of interpositional spacers.
    Clinical Biomechanics 06/2008; 23(8):1044-52. DOI:10.1016/j.clinbiomech.2008.04.006 · 1.88 Impact Factor
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    ABSTRACT: We report the first case of early postoperative infection after a medial hemiarthroplasty of the knee with a customized ConforMIS iForma™ interpositional device. The infection was treated successfully by revision surgery with implant removal and antibiotic therapy. Despite the additional diagnosis of rheumatoid arthritis that did not affect the treated knee, the preservation of bony and ligamentous structures enabled a successful re-implantation of another iForma™ implant 9 months later with good clinical results at follow-up examination 1 year postoperatively. This is very much in contrast to the extensive and complex revision surgery, with significant bone loss, in patients with infected unicompartmental or total knee arthroplasties. The iForma™ device may be an alternative treatment option in early and moderate unicompartmental arthritis of the knee, with easy revision with the same type of implant in the rare case of infection. KeywordsUnicompartmental osteoarthritis-Knee interpositional device-Hemiarthroplasty-Complication
    Central European Journal of Medicine 08/2010; 5(4):442-446. DOI:10.2478/s11536-009-0135-1 · 0.21 Impact Factor
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