The Hallux Metatarsophalangeal Capsule: An Anatomic Study With Respect to Percutaneous Hallux Valgus Correction.

BACKGROUND: Minimally invasive surgery for the treatment of hallux valgus deformities has become increasingly popular. Knowledge of the location of the hallux metatarsophalangeal (MTP) proximal capsular origin on the metatarsal neck is essential for surgeons in planning and executing extracapsular corrective osteotomies. A cadaveric study was undertaken to further study this anatomic relationship. METHODS: Ten nonpaired fresh-frozen frozen cadaveric specimens were used for this study. Careful dissection was performed, and the capsular origin of the hallux MTP joint was measured from the central portion of the metatarsal head in the medial, lateral, dorsal, plantarmedial, and plantarlateral dimensions. RESULTS: The ten specimens had a mean age of 77 years, with 5 female and 5 male. The mean distances from the central hallux metatarsal head to the MTP capsular origin were 15.2 mm dorsally, 8.4 mm medially, 9.6 mm laterally, 19.3 mm plantarmedially, and 21.0 mm plantarlaterally. CONCLUSION: The MTP capsular origin at the hallux metatarsal varies at different anatomic positions. Knowledge of this capsular anatomy is critical for orthopaedic surgeons when planning and performing minimally invasive distal metatarsal osteotomies for the correction of hallux valgus. TYPE OF STUDY: Cadaveric Study.

Biomechanical Evaluation of Custom Foot Orthoses for Hallux Valgus Deformity.

The purpose of the present study was to compare the hallux valgus deformity pressure parameters seen in standard footwear (no orthosis) versus the pressure observed in the same footwear with the addition of 3 different length orthoses. The forefoot pressure at a hallux valgus deformity was recorded with pressure sensors placed on the plantar, medial, and dorsal surface of the first metatarsal head. The participants performed walking trials without an orthosis and with orthoses of 3 different lengths. The average pressure and maximum pressure of each area was recorded for each orthosis, and comparisons were made across the groups. The plantar pressures were decreased in the full length and 3/4 length orthoses, and the dorsal pressures were increased with the use of the full-length and sulcus-length orthoses. Significant changes in medial pressure were not seen with the addition of any orthosis compared with standard footwear alone. However, a trend toward increased medial pressures was seen with the full- and sulcus-length orthoses, and the 3/4-length orthoses exhibited a trend toward decreased medial pressures. We were unable to demonstrate that the use of a custom foot orthosis significantly decreases the medial pressures on the first metatarsal head in patients with hallux valgus deformity. The 3/4-length orthosis was less likely to negatively affect the dorsal or medial pressures, which were noted to increase with the sulcus- and full-length orthoses. Our data suggest that if a clinician uses this treatment option, a 3/4-length orthosis might be a better choice than a sulcus- or full-length orthosis.