Abstract
Background
Historically, a functional ACL has been a prerequisite for patients undergoing unicondylar knee arthroplasty (UKA). However, this premise has not been rigorously tested.
Questions/purposes
We compared (1) the survivorship free from revision and (2) the failure mechanisms of UKAs in ACL-deficient knees and UKAs in ACL-intact knees performed over the same time interval.
Methods
Between November 2000 and July 2008, a fixed bearing UKA was performed in 72 patients (81 knees) with intraoperatively confirmed ACL deficiency. Five patients (five knees) with preoperative instability underwent ACL reconstruction and were excluded from analysis. Of the remaining 67 patients (76 knees) without preoperative instability, implant status was known for 68 UKAs in 60 patients. Survivorship and failure mechanisms for these knees were compared to those of 706 UKAs in ACL-intact knees performed during the same time interval by the same surgeon using the same implant system. Minimum followup for the ACL-deficient group was 2.9 years (mean, 6 years; range, 2.9–10 years).
Results
Revision rates between UKAs with and without intact ACLs were similar in the absence of clinical instability (p = 0.58). Six-year UKA survivorship was 94% (95% CI: 88%–100%) in ACL-deficient knees and 93% (95% CI: 91%–96%) in ACL-intact knees (p = 0.89). Five knees (7%) in the ACL-deficient group were revised: disease progression (two), loose tibia (one), persistent pain (one), and revised elsewhere/reason unknown (one). Thirty-six knees in the ACL-intact group underwent revision (5%): aseptic loosening (13), revised elsewhere/reason unknown (11), disease progression (three), tibial subsidence/fracture (four), infection (three), pain (one), and lateral compartment overload (one).
Conclusions
At 6 years, deficiency of the ACL in patients without clinical knee instability did not impact the survivorship of UKAs compared to UKAs performed in knees with intact ACLs.
Level of Evidence
Level III, prognostic study. See Instructions for Authors for a complete description of levels of evidence.
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The institution of the authors has received institutional support from the Inova Health System (Falls Church, VA, USA) and DePuy, A Johnson & Johnson Company (Warsaw, IN, USA). One of the authors certifies that he (GAE), or a member of his immediate family, has received or may receive payments or benefits, during the study period, an amount of USD 100,001 to USD 1,000,000 from DePuy and an amount of USD 10,000–USD 100,000 from Smith & Nephew Inc (Memphis, TN, USA). One of the authors certifies that he (GAE) has board membership, consultancy, patents pending, and stocks from TGS Knee Innovations (Plymouth, MN, USA), but he received no monetary payment or benefit during the study period.
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Engh, G.A., Ammeen, D.J. Unicondylar Arthroplasty in Knees With Deficient Anterior Cruciate Ligaments. Clin Orthop Relat Res 472, 73–77 (2014). https://doi.org/10.1007/s11999-013-2982-y
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DOI: https://doi.org/10.1007/s11999-013-2982-y