Dr. Kevin C. Chung and colleagues at The University of Michigan Health System, Ann Arbor note that silicone implants have been used for many years to replace such destroyed joints. Results are reportedly good but studies have often provided a low level of evidence because of shortcomings such as brief follow-up and lack of controls.
To better understand outcome, the team conducted a multicenter prospective cohort study initially involving 67 RA patients with severe metacarpophalangeal joint deformities who elected to undergo SMPA. They were compared with 95 similar patients who did not undergo SMPA.
The surgical group had worse Michigan Hand Outcomes Questionnaire (MHQ) function and functional measurements at baseline. At 3 years, data were available for 42 surgical subjects and 73 nonsurgical subjects.
These showed a significantly greater improvement in the mean overall MHQ score and the MHQ function in the surgical group. This was also true of activities of daily living, aesthetics and satisfaction scores.
Ulnar deviation, extensor lag and arc of motion in the metacarpophalangeal and proximal interphalangeal joints also improved significantly in the surgical group. These were dramatic changes, say the investigators.”We found an average 20 degree improvement in ulnar drift and 30 degree improvement in extensor lag over 3 years.”
No improvement was seen in mean Arthritis Impact Measurement Scales, grip/pinch strength. Despite this, the researchers point out that “SMPA allows the patient to open and close their hands more easily.” They also suggest that MHQ scores may be more informative than traditional measures such as grip and pinch strength.
The complication rate, say the researchers, was “minimal.” One complication that can arise from SMPA is implant fracture. This has ranged as high as 67% in some studies. The 3-year fracture rate in the current study was 9.5%.
Summing up, Dr. Chung told Reuters Health by email that after 3 years “compared to similar non-surgically treated patients, the SMPA patients continued to have better hand outcomes.”