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Do you have tips for patients who received a pyrolytic carbon implant for osteoarthritis of the MCP joint?

Q: I am a Physical Therapist who subscribes to your service -- it has been a great help to me. Tomorrow I will be seeing two patients who both received a pyrolytic carbon implant for osteoarthritis of the MCP joint. What tips can you offer me for designing the rehab program? What do other hand therapists do for these patients?

A: The implant is made by burning and separating hydrocarbon gas to make it chemically stable. The process makes the material biologically compatible (acceptable to the body). Pyrolytic carbon implants have been around and in use for finger joint replacements for 20 years or more. But the use of these devices for osteoarthritis (OA) of the metacarpophalangeal (MCP) joints has been limited. In fact, there is very little data reported on the results (especially long-term outcomes) for this condition.

A recent study from Washington University in St. Louis has some information that may be helpful. A single surgeon performed joint replacements for nine patients in 11 metacarpophalangeal (MCP) joints (index and middle fingers). The patients were followed for at least two full years.

Results were measured using pain, motion, function, and patient satisfaction. Assessment tools included the Michigan Hand Questionnaire and the Quick Disabilities of the Arm, Shoulder, and Hand survey. X-rays were used to look for implant loosening, fracture, movement, subsidence (sinking down into the bone), or failure of any kind.

The surgeon reported that motion was significantly improved from before surgery to after. Grip strength was better than before surgery but less than the other hand. Pain was mild (rated as a one on a scale from zero to 10) if there was any pain at all. And there was high satisfaction associated with 10 of the 11 fingers.

There were a few problems reported along the way. Two of the patients noticed clicking and squeaking when they moved the finger. There were no other symptoms accompanying the noises (e.g., no pain, no swelling, no tenderness). One patient who was unhappy with the results had joint stiffness, constant pain, and squeaking for no apparent reason. She ended up having a joint fusion (arthrodesis) seven months later. In general, there was no sign of implant failure for any of the patients. Everyone had a little subsidence (implant sinking down) but this did not continue to get worse and presented no problems.

Postoperative rehabilitation was initiated 10 to 14 days after surgery. Edema control was an important focus. A splint was provided to maintain the MCP joint in full extension for six weeks. Patients were instructed and encouraged to perform active motion of the other joints of the finger. After six weeks, the splint could be removed while patients performed light activities.

Three weeks after surgery, the patients were shown how to do short arc motion of the MCPs starting at 30-degrees. These exercises were repeated three or four times each day. MCP flexion was gradually increased by 10 degrees each week until full motion was restored.

Strengthening was started eight to 10 weeks after surgery. The hand therapist started each patient off slowly and gently. About this time, the daytime splint was gradually phased out but the splint was still worn throughout the night for three to six months. The time lines for all of these separate treatment components were worked out for each patient between the therapist and the surgeon. You may want to provide a proposed treatment plan and consult with the surgeon for your two patients.

Reference: Lindley B. Wall, MD, and Peter J. Stern, MD. Clinical and Radiographic Outcomes of Metacarpophalangeal Joint Pyrolytic Carbon Arthroplasty for Osteoarthritis. In The Journal of Hand Surgery. March 2013. Vol. 38A. No. 3. Pp. 537-544.