Because ankle inversion trauma can result in persistent isolated subtalar joint instability and can contribute to chronic lateral ankle instability, optimization of subtalar joint ligament injury diagnosis and treatment is essential.

12 fresh-frozen cadaver lower extremities were used. The cradle was a component of a gimbal system that allowed unrestricted inversion/eversion and anterior-posterior and medial-lateral translation of the subtalar joint. The bearing system to which the tibia/fibula were attached allowed unconstrained internal/external rotation and superior-inferior translation. 4N-m inversion/ eversion and internal/external rotational moments and translational forces of 67N were applied. All measurements were performed sequentially in neutral, 10° dorsiflexion and 20° plantarflexion, and were repeated as the cervical, calcaneofibular, and interosseous ligaments were consecutively sectioned in all possible different orders.

In neutral position, inversion increased after sectioning of the cervical (3.7°), interosseous (0.8°), and calcaneofibular (1.9°) ligaments individually. Combined sectioning of all three ligaments showed an increase in inversion of 8.3°, 8.5° and 1.4° in the neutral, plantarflexed, and dorsiflexed positions, respectively, compared to the intact ankle. External rotation also increased in neutral position after sectioning the cervical ligament (2.0°). Combined sectioning of all ligaments showed an increase in external rotation of 3.6° and 5.4° for neutral and dorsiflexion, respectively.

This is the first comprehensive biomechanical cadaver study of the contributions of the cervical, calcaneofibular, and interosseous ligaments to stabilization of the subtalar joint. The surgeon may refer to the findings in both diagnosing and planning treatment of problematic subtalar joint instability

Purpose: Currently, the modified Kidner procedure is recommended to treat the symptomatic accessory navicular that fails nonoperative management. Some foot and ankle specialists have cautioned that excision of the accessory navicular can lead to a progressive increase in pain and loss of the longitudinal arch. As a result, they have recommended ORIF of the symptomatic accessory navicular as a surgical alternative. To our knowledge, the only references to this surgical alternative in the orthopedic literature are two technique papers.

Method: Between 1999 and 2005, 17 patients were treated with symptomatic type II accessory naviculars that failed nonoperative measures. A standard treatment algorithm was followed:

accessory naviculars of adequate size underwent an ORIF (10), and

Corrective osteotomies and/or soft-tissue procedures were performed concomitantly in nine patients to address pes planus. Pre- and postoperatively, patients were assessed radiographically. Preoperative MRI scans were analyzed to see if there was any correlation between MRI findings and success of ORIF. Patients were evaluated with the AOFAS midfoot clinical rating system (max 100 points).

Results: In the patients treated with ORIF, average follow-up was 31 months. The average AOFAS mid-foot score improved from 49 to 89 points. Radiographic analysis suggested an 80% union rate. However, only one patient out of ten (10%) undergoing ORIF with subsequent nonunion was symptomatic and her pain resolved after screw removal. In the patients treated with excision, average followup was 48 months. The average AOFAS score improved from 45 to 78 points. Three of seven feet (43%) treated with accessory navicular excision had persistent midfoot pain at last followup with clinical and radiographic signs of progressive loss of the longitudinal arch. Twelve patients had a preoperative MRI of the foot with all showing edema suggesting an injury to the synchondrosis. We found no correlation between MRI findings and success of ORIF of the accessory navicular.

Conclusion: As suggested by previous technique papers and this study, ORIF of the symptomatic type II accessory navicular may have merit. We anticipate that this study will prompt a comprehensive multicenter evaluation of this technique.