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Introduction: Several cadaveric studies have demonstrated volar intercalated segmental instability (VISI) after sequential sectioning of ligaments on the ulnar side of the carpus.  Based on these studies, one would expect that a partial ulnar carpal excision for tumor management would result in a VISI deformity.  We present a series of four patients that were treated with partial ulnar carpal excisions in the course of their treatment for rhabdoid-like sarcoma, chondrosarcoma, melanotic schwannoma, or clear cell sarcoma.   Despite the surgical excisions and subsequent clinical loading of the carpus, none of the four patients demonstrated VISI deformities on follow-up imaging.

Methods: Lateral wrist radiographs were evaluated to determine lunate position (volar or dorsal tilt), the scapholunate (SL) angle, and the capitolunate (CL) angle on the pre-operative images and post-operative images taken at the latest available follow-up.  Information on range of motion, pain, and symptoms of instability was gathered from medical records.

Results: After an average follow-up time of 4.7 years, the lunate remained in a neutral position on the lateral radiograph in all four patients.  All patients had SL angles within the normal range of 30 to 60 degrees, and the mean post-operative SL angle was 42 degrees (range 31-57).   The mean change in the SL angle from the pre-operative measurement to the final follow-up measurement was 6.2 degrees (range 1-10).  The average post-operative CL angle was 34 degrees (range 17-65).  The patient with a 65 degree CL angle had a flexed capitate, but his lunate remained neutral and his SL angle of 48 degrees was not suggestive of VISI.  The mean change in the CL angle was 16 degrees.  No patients reported pain or other symptoms of instability.  Two patients had decreased range of motion in wrist flexion and extension.

Discussion: The lack of carpal instability in this series of four patients was an unexpected finding because it is contrary to what the cadaveric studies would predict after partial ulnar carpal excision.  Perhaps post-operative scar tissue provided some stability to the otherwise destabilized ulnar carpus, but the lack of VISI in these patients suggests that our understanding of carpal kinematics from prior cadaveric studies is limited.  To date, no clinical studies have reported results after partial ulnar carpal excisions for tumor management.  The results from this limited series suggest that partial ulnar carpal excisions can be performed for tumor management without significant concerns over the development of subsequent VISI deformity.