Silicone metacarpophalangeal joint arthroplasty yielded benefits that persist out to 7 years
In patients with rheumatoid arthritis, silicone metacarpophalangeal joint arthroplasty provided benefits that were sustained for up to 7 years and had low rates of implant fracture or deformity, according to recently published results.
In the prospective, multicentered, international NIH-funded study, researchers evaluated patients aged 18 years to 80 years and diagnosed with rheumatoid arthritis. Eligible participants also had severe deformity at the metacarpophalangeal joint joints, defined by combined coverage ulnar deviation and average extensor lag of at least 50° for four fingers. Participants were enrolled from three study sites between 2003 and 2008.
At baseline, patients consulted with a hand surgeon and chose whether they wanted to undergo metacarpophalangeal joint arthroplasty (SMPA group, n=73) in addition to medical management or medical management only (non-SMPA group, n=97). Patients in the SMPA group chose which hand they would have the SMPA procedure on, while the non-SMPA group chose a hypothetical hand to undergo the procedure. SMPA patients were eligible to undergo SMPA on their other hand after 1 year, and patients in the non-SMPA group were permitted to cross over into the SMPA group after 1 year.
Patients were assessed at enrollment, 6 months, 1 year and annually thereafter up to 7 years. The following functional evaluations were made: grip strength; lateral pinch; two-point pinch; three-point pinch; and the Jebsen-Taylor test, a timed test that measured ability to complete seven common tasks of daily life. At each study location, a designated hand specialist determined ulnar drift, extensor lag at the MCP joints and arc of motion at the MCP joints. In addition, the researchers tracked patient-reported outcomes, including the Michigan Hand Questionnaire (MHQ) and the arthritis impact measurement scales questionnaire. SMPA implants were assessed by radiograph and were categorized as intact, deformed or fractured.
In terms of baseline objective measurements, researchers found patients in the non-SMPA group had significantly stronger grip and two-point and three-point pinch strength vs. the SMPA group. During the follow-up, the SMPA group maintained their baseline strength levels in all measures, while the non-SMPA group showed some lessening in pinch strengths. As a result, there were no baseline-adjusted, between-group differences during follow-up, with the exception of a between-group difference in grip strength at 3 years.
At baseline, the SMPA group had worse or significantly worse outcomes vs. the non-SMPA group in terms of ulnar drift, extensor lag and arc of motion. However, during the 7-year follow-up, the SMPA group showed consistently better outcomes vs. the non-SMPA group for each of these measures. This persisted even at year 7, when ulnar drift, extensor lag and arc of motion showed better outcomes in crude means vs. the non-SMPA group, and these significantly better outcomes persisted after adjustments.
In terms of patient-reported outcomes, the non-SMPA group demonstrated superior scores in all domains of the MHQ vs. the SMPA group. During the 7 years, although the SMPA group generally did not score higher on the MHQ than the non-SMPA group, the SMPA group demonstrated substantial, sustained improvement; for example, the crude change at year 7 in function score was 0.61. At year 7, the SMPA group had significantly better baseline-adjusted predicted outcomes vs. non-SMPA group for function, aesthetics, satisfaction and overall summary score.
“This study found that benefits of silicone metacarpophalangeal joint arthroplasty, such as improved function and decreased ulnar drift, were maintained over 7 years of follow-up,” the researchers wrote. “Previous studies of silicone metacarpophalangeal joint arthroplasty did not compare surgical patients to nonsurgical patients. We found that patients who did not choose to undergo this procedure (nonsurgical patients) maintained their baseline hand function over the 7-year study duration.” – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.