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AAOS Now

Published 2/1/2016

Study Finds MCP Arthroplasty Safe, Successful

Analysis of 583 arthroplasties shows few complications
A promising treatment for patients with inflammatory arthritis, according to a paper presented at the 2016 annual meeting of the American Association of Hand Surgeons, is metacarpophalangeal (MCP) arthroplasty. This study compared the most common implant designs in terms of implant survival rates, finger and hand function, and surgical complications.

The researchers, all of whom are from the Mayo Clinic in Rochester, Minn., used the institution's total joint registry to identify 583 MCP arthroplasties performed in 142 patients with inflammatory arthritis during a 12-year period. Approximately two-thirds (63 percent) of the MCP arthroplasties were performed on the patient's dominant hand.

The average age of the patients included in the study was 61 years; 86 percent were females. Important to note, 11 percent of patients were smokers and 12 percent had diabetes mellitus (DM).

The three implant types studied were pyrocarbon implants (used in 155 surgeries); silicone implants (used in 366 surgeries); and surface replacement arthroplasty (SRA) implants (used in 61 surgeries). Patient characteristics, with the exception of age, did not differ significantly among the three groups. The average age of patients who received silicone implants was 66 years; patients who received pyrocarbon or SRA implants were younger (average age 53 and 54 years respectively).

Comparable results
Researchers found a total of 38 revision surgeries performed at an average of 2 years postoperatively. Overall, MCP arthroplasties had good medium-term implant survival rates at 2, 5, and 10 years (98 percent, 95 percent, and 87 percent, respectively). The three implants had similar 5-year survival rates (Fig. 1); 91 percent for pyrocarbon implants; 84 percent for SRA implants; and 99 percent for silicone implants.

Researchers calculated that, compared to patients who received a silicone implant, patients who received an SRA or pyrocarbon implant had a significantly greater risk of revision surgery (P = 0.001 for SRA implants, and P = 0.005 for pyrocarbon implants). In reviewing the cases, researchers also found that the use of cement and, as would be expected, the occurrence of an intraoperative fracture also increased the risk of implant failure.

At a mean 5 years follow-up (range, 2 to 10 years), researchers found that pain levels had significantly improved from preoperative levels in patients with their index implant still intact. However, no significant changes between preoperative and postoperative values were noted in total arc of motion, grip strength, or pinch strength.

Complications
Intraoperative complications included periprosthetic fractures in 15 patients. Postoperative complications included 19 dislocations, 2 cases of heterotopic ossification (HTO), 4 periprosthetic fractures, and 9 infections. When complications were analyzed by implant type, researchers found that pyrocarbon implants were associated with an increased rate of dislocation (P = 0.001).

Conclusion
Based on their analysis, researchers concluded that "MCP arthroplasty for inflammatory arthritis can be a successful motion-sparing procedure with reasonable medium-term survival and low complications. Patients experience predictable pain relief and maintenance of their motion." They noted, however, that silicone implants were associated with a slightly higher survival rate than the other two types of implants studied in patients with inflammatory arthritis.

Coauthors of "Metacarpophalangeal Arthroplasty for the Management of Inflammatory Arthritis: An Analysis of 583 Arthroplasties" are Eric R. Wagner, MD; Matthew Houdek, MD; Robert E. Van Demark Jr, MD; Steven L. Moran, MD; and Marco Rizzo, MD. The authors' disclosure information can be accessed at www.aaos.org/disclosure

Bottom Line

  • This study reviewed the results of 583 metacarpophalangeal (MCP) arthroplasties performed in 142 patients with inflammatory arthritis involving the hand.
  • Researchers compared results among three different types of implants—pyrocarbon, surface replacement, and silicone—with respect to complications, clinical outcomes, and rates of revision surgery.
  • Regardless of implant type, patients experienced "predictable pain relief and maintenance of their motion" but no significant improvements in their grip or pinch strengths.
  • Silicone implants were associated with a higher survival rate; pyrocarbon implants were associated with an increased rate of dislocation.