Revision of Minimal Resection Resurfacing Unicondylar Knee Arthroplasty to Total Knee Arthroplasty: Results Compared With Primary Total Knee Arthroplasty

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Abstract

We compared a cohort of patients undergoing revision of a minimal resection resurfacing unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) with a cohort of patients undergoing primary TKA. Both cohorts were matched in terms of age, sex, and body mass index. We collected data on preoperative and postoperative range of motion, International Knee Society scores, and radiologic data. We also collected data on the modes of failure of the primary UKA. There were 55 patients in each cohort. The average time the UKA was in place was 48.3 months. The average follow-up period from the time of revision was 39.2 months. The most common reason for revision was subsidence of the tibial base plate (58%). Forty percent of patients required particulate bone grafting for contained defects. Two patients required metal augments, and 1 required stems. There was no significant difference between the 2 groups in terms of range of motion, functional outcome, or radiologic outcomes. Revision of these types of implants to TKA is associated with similar results to primary TKA and is superior to revision of other forms of UKA.

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Materials and Methods

We retrospectively reviewed the records of 55 patients (group A), all consecutive, who underwent TKA for a failed UKA from 2003 to 2008. All patients were identified via the senior author's (M.J.N.) database, and information recorded included the usual demographic data and data from the primary procedure, including whether the degenerative changes were confined to the compartment that was replaced, the initial postoperative hip-knee-ankle (HKA) alignment of the limb, and the position of the

Results

The average time the UKA was in place before revision was 48.3 months (range, 5-112 months). The average follow-up period in group A was 39.2 months (range, 6-127 months), and in group B, it was 38.4 months (range, 24-65 months).

Table 1 demonstrates the reason for failure of the UKA. The most common reason for revision was subsidence of the tibial base plate (Fig. 2), accounting for 58% of all revisions. The average time to revision for this complication was 40 months (range, 6-99 months). When

Discussion

Unicompartmental knee arthroplasty is becoming an increasingly performed procedure for unicompartmental osteoarthritis in younger patients. This can be partly explained by the advent of minimally invasive techniques and better implant design.

However, there remains concern as to the longevity of the implants, especially in younger more active patients. In addition, the use of bone graft, augments, and stems may be required when converting a UKA to TKA.

The use of minimal resection techniques for

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    The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2012.02.031.

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