Hemicondylar hamate replacement arthroplasty for proximal interphalangeal joint fracture dislocations: an assessment of graft suitability.

PURPOSE: Proximal interphalangeal (PIP) joint fracture-dislocations are complex injuries, and successful surgical treatment can be challenging. The hamate appears to be an appropriate graft based on its general shape and dimensions. The purpose of this study was to evaluate the rationale and suitability of the hamate as an autograft for proximal interphalangeal joint fracture-dislocations and to determine the inherent stability of the donor site after graft harvesting.

METHODS: Fresh-frozen cadaveric hand specimens were used to evaluate the hamate as a suitable graft source for defects of the middle phalanx based on macroscopic, radiographic, and biomechanical properties. Radiographic measurements were made of the articular contours of the hamate and the base of middle phalanx of digits 2 through 5. Hemicondylar hamate replacement arthroplasty (HHRA) was performed in cadavers for defects created in the middle phalanges. Biomechanical stability testing of the hamate-metacarpal joint was then assessed in additional specimens before and after HHRA. Fluoroscopic examination with a 22.2-N load applied in a 45 degrees dorsal-proximal direction was used to assess stability of the carpometacarpal joints. A servohydraulic testing machine was then used to determine the amount of translation induced with a similarly directed force before and after harvesting of the hamate graft.

RESULTS: The cadaveric HHRA reconstructions restored joint stability with no tendency to subluxate. Radiographic measurement showed that the hamate has a central ridge and bicondylar facet with articular contours that are similar to the base of the middle phalanx. The removal of a central portion of the hamate did not induce dislocation or create obvious clinical instability of the carpometacarpal joint.

CONCLUSIONS: The HHRA technique is used for treatment of fracture-dislocations of the proximal interphalangeal joint. This study demonstrated the suitability of using the dorsal portion of the hamate as an osteochondral autograft for middle phalangeal base fractures; the technique creates minimal donor site morbidity.