Abstract
Introduction
While prosthesis survival in Total Knee Arthroplasty (TKA) exceeds 90% at 10 year, failures do occur. One area of concern has been the potential for metal allergy or metal sensitivity causing persistent pain, swelling or early failure of the implant in some patients. Definitive tests for diagnosing metal allergy and metal sensitivity have not been developed and this field remains controversial. In most cases where metal sensitivity is a concern, metals such as Chromium and Nickel are implicated. Despite the lack of good diagnostic tests for identifying these patients, several orthopedic prosthesis manufacturers have developed implants made of Titanium or ceramic designed for use in patients where concerns exist regarding metal allergy. In the absence of good diagnostic tests, use of these devices in patients that self identify is one option. To date, little information has been presented about the incidence of self reported metal sensitivity in patients undergoing joint replacement. This study was undertaken to determine the incidence of self reported metal allergy or sensitivity in patients undergoing total knee arthroplasty.
Methods
An IRB approved, retrospective chart review was performed in a consecutive series of 194 patients who had undergone TKA at one institution, with one surgeon. Self reported metal sensitivity and allergy had been routinely elicited from each individual who had not undergone implantation of a previous metallic device, during pre-operative consultation.
Results
36 of the 194 patients had a previously well functioning implanted metal device. In addition, data was missing in 19 patients. Therefore, data from 139 out of 158 consecutive patients who had no prior implanted metal devices was available. 20 of 139 patients (14%) reported a known metal allergy or sensitivity. This included 19 of 86 females (22%) and 1 of 53 males (2%). This difference was statistically significant (P=0.001).
Conclusions
If self reported prior metal sensitivity or allergy is used to guide prosthesis selection in TKA, approximately 14% of patients would be candidates for “hypo-allergenic” prostheses. If only particular sizes of components are offered in these alternative materials, smaller sizes or female gender specific sizes should be considered due to the higher incidence of self reported metal allergies in female patients.
