Hallux valgus and first ray mobility: a cadaveric study.

BACKGROUND

Several studies have demonstrated that patients with hallux valgus (HV) deformities have increased first ray sagittal mobility. However, the change in mobility that occurs after surgical correction of HV deformities has not been extensively evaluated. This study was done to determine if surgical realignment of the first ray in cadaver specimens with a proximal crescentic osteotomy and distal soft tissue reconstruction (DSTR) would reduce the first ray sagittal motion as measured with an external-type micrometer (the Klaue device).

METHODS

Twelve fresh-frozen below-knee cadaver specimens with an HV deformity (HV angle > 15 degrees, 1-2 IM angle > 9 degrees) were used for the study. Standardized simulated weightbearing radiographs were obtained before and after the surgical correction of the deformity. The first ray sagittal motion was measured with an external micrometer (Klaue device) before correction of the HV deformity and after the procedure. All specimens had correction of the hallux valgus deformity with a DSTR and proximal crescentic osteotomy. Internal fixation was applied to secure the osteotomy site.

RESULTS

The HV angle was corrected from a mean of 28.6 degrees to a mean of 11.0 degrees. The 1-2 IM angle was corrected from a mean of 12.9 degrees to a mean of 6.8 degrees. The average preoperative first ray sagittal motion was 11.0 mm (range, 8.5 mm to 13.5 mm). After the surgical repair, the mean sagittal first ray motion was significantly decreased (p <.0005) to a mean of 5.2 mm (range, 3.5 mm to 7.5 mm).

CONCLUSION

After correction of HV deformities with a DSTR and a proximal crescentic osteotomy, first ray mobility in cadaver specimens was significantly reduced. The stabilization of first ray mobility that occurred immediately after surgical correction despite leaving the capsule of the first metatarsocuneiform (MC) joint undisturbed suggests that extrinsic anatomic features may play a role in first ray mobility. Additionally, stability of the first ray may be restored with a bunion procedure that does not sacrifice the first MC joint.