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Duke Orthopaedics
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Wheeless' Textbook of Orthopaedics

Lunate Implant



- Discussion:
    - lunate shaped spacer implant made of silicone, vitallium, acrylic, or rolled-tendon is inserted into theresulting space to prevent migration of 
           other carpal bones;
    - due to the high rate of synovitis, most surgeons are now reluctant to use lunate implants;

- Technical Considerations:
    - dorsal approach is used, the capsular structures are preserved, distal part of the 4th compartment is incised, and EDC tendons are 
          retracted ulnarly;
    - lunate is removed piecemeal;
    - tendon spacer:
           - roll the palmaris longus overr a small portion of the excised lunate (alternatively use the ECRB);
    - artificial spacer:
           - use an absorbable suture through the prosthesis and into triquetrum, and also elevates a generous portion of the dorsal 
                  retinaculum from the extensor tendons over the fourth and fifth radial canal;
           - this is left attached to the radial border and is then sutured to dorsal surface of the scaphoid and the triquetrum;
    - it is important to reconstruct the wrist ligaments & palmar joint capsule inorder to prevent displacement of the implant;

- Hazards:
    - silicone synovitis:
           - although synovitis is seen less often w/ the lunate prosthesis as compared to the scaphoid implant, the results are still unacceptably 
                  high;
           - synovitis is more prevalent in young active patients;
           - the longer the implant is left in place, the more wear debris is present;
           - removal of the implant and debridement may not necessarily improve the silicone induced pain and limitation of motion


Kienbock's disease: the role of silicone replacement arthroplasty.

Use of a hand-carved silicone-rubber spacer for advanced Kienbock's disease.

The results of treatment of synovitis of the wrist induced by particles of silicone debris.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, April 12, 2012 2:02 pm