Clinical Example: Pyrolytic carbon metacarpophalangeal joint implant arthoplasty

Small joint arthoplasty has been an ongoing problem of hand surgery.  The delicate and anatomically precise joints of the fingers function within a very narrow tolerance of friction and mechanical balance of bone and soft tissue forces. Historically, rigid (metal and plastic) implants have failed because the mechanical mismatch at the bone-implant interface has resulted in implant displacement due to reactive bone remodelling. Flexible (silicone rubber) implants have failed because of implant breakage, erosive reaction to implant wear debris, and inability of flexible implants to provide rotational and lateral stability. 

Pyrolytic carbon implant arthroplasty of the finger joints appears to be an improvement on previous strategies, as it mimics the normal joint mechanics, in movement, lack of wear debris and a close match to the mechanical characteristics of the finger bones.


 
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Pyrolytic carbon implants for proximal interphalangeal joints (upper pair) and metacarpophalangeal joints (lower pair) are shown below (palmar view). Examples of proximal interphalangeal joint implants are posted here and  here.
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Phalangeal component on the left, metacarpal component on the right, palmar view.
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Lateral view.
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Rheumatoid metacarpophalangeal joint changes, metacarpal head.
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and after implant placement.
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Dorsal view of joint:
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and after implant placement.
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Lateral view of joint, showing chronic palmar subluxation -
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and after implant placement, subluxation corrected.
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Pre and postop radiographs.
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