Abstract
BackgroundMetal sensitivity as a cause for painful joint replacement has become increasingly prevalent; however, there is a lack of reported clinical outcome data from total knee arthroplasty patients with metal allergies. The purpose of this study was to determine whether patients presenting with a painful total knee arthroplasty with a positive metal sensitivity have improved outcomes following revision to a hypoallergenic implant.MethodsA retrospective review was conducted for patients that underwent a revision total knee arthroplasty after metal sensitivity testing over a 3-year period from January 1, 2015, to December 31, 2017. Based on the results of sensitivity testing, patients underwent revision total knee arthroplasty to a hypoallergenic component or a standard component. Following revision, patients returned to the clinic at an interval of 6 weeks, 5 months, and 12 months for functional, pain, and satisfaction assessment. Outcomes were compared within and between sensitivity groups.ResultsOf the included patients, 78.3% (39/46) were positive for metal sensitivity. The most common metal sensitivity was to nickel (79.5%, 32/39). Both non-reactive and reactive patients significantly improved in range of motion after revision arthroplasty. The reactive group saw a 37.8% decrease in pain at 6 weeks post-revision (p < 0.001) Whereas, the non-reactive group only saw a moderate, non-significant improvement in pain reduction at 6 weeks post-revision (27.0%; p = 0.29). Frequency of pain experienced did not vary significantly between groups. Maximum metal lymphocyte transformation test (LTT) sensitivity score did not correlate with pain level at the time of revision (R2 = 0.02, p = 0.38) or percent improvement after revision (R2 = 0.001, p = 0.81). Overall, all patients reported being very satisfied after revision total knee arthroplasty; there was no difference between positive and negative sensitivity groups (W = 62, p = 0.89).ConclusionsPatients presenting with a painful knee arthroplasty and positive metal LTT have improved pain scores, walking function, and range of motion following revision to a hypoallergenic component. This study also provides a treatment algorithm for patients presenting with a painful knee replacement, in order to provide effective and timely diagnosis and management.
Highlights
Metal sensitivity as a cause for painful joint replacement has become increasingly prevalent; there is a lack of reported clinical outcome data from total knee arthroplasty patients with metal allergies
Despite excellent results seen with primary knee arthroplasty, ranging from 75 to 92% good or excellent results, approximately one in five patients remain “dissatisfied” with their total joint replacement often leading to revision total knee arthroplasty (TKA) [2, 3]
When compared to baseline measures, both non-reactive and reactive patients significantly improved in range of motion after revision arthroplasty (Fig. 3)
Summary
Metal sensitivity as a cause for painful joint replacement has become increasingly prevalent; there is a lack of reported clinical outcome data from total knee arthroplasty patients with metal allergies. Despite excellent results seen with primary knee arthroplasty, ranging from 75 to 92% good or excellent results, approximately one in five patients remain “dissatisfied” with their total joint replacement often leading to revision TKA [2, 3]. The most common causes leading to revision TKA reported in the literature include infection, instability, and malalignment [4]. Workup of the patient includes extensive labs and imaging, which leads to a diagnosis in the majority of patients Despite these measures, there remains a subset of patients with a painful TKA and a negative workup without an identifiable cause
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