OBJECTIVETo evaluate the clinical outcome of accessory navicular fusion for treatment of the painful accessory navicular bone of type II in adults.

METHODSFrom June 2006 to June 2012, a total of 38 feet (in 35 adult patients) with painful accessory navicular with type I underwent an fusion operation of the primary and accessory navicular bones,including 26 males and 9 females with a mean age of (32.4±7.3) years old ranging from 18 to 44 years old. The course of disease ranged from 3 to 10 months. The perioperative complications and radiological outcomes were observed and recorded. The foot function before and after operation were assessed by the American Orthopedic Foot and Ankle Society (AOFAS) midfoot score, and the easement of the pain was evaluated by visual analog score (VAS).

RESULTSTwo patients had transient superficial inflammation of the incision, no obvious perioperative complications occurred. All patients were follow-up for (53.5±14.7) months (12 to 84 months). Bone union was confirmed on plain radiography in 32 cases (35 feet). The mean time from the operation to union was (13.7±2.3) weeks (9 to 18 weeks). Postoperative pain VAS score was improved obviosly than preoperative (V=12.14,P< 0.01). The talar-to-first metatarsal angle [(9.4±3.5)° vs (8.3±2.7)°, t=0.736, P>0.05)], calcaneal tilt angle [(17.7±2.2)° vs (18.9±3.4)°, t=0.794, P>0.05],talonavicular uncoverage angle [(14.3±3.4)° vs(12.5?4.6)°,t=0.947, P>0.05) ],and height of the first tarsometatarsal joint [(14.8±3.1) mm vs (15.9±2.8) mm,t=0.814,P>0.05)] before and after operations had no statistic difference. The AOFAS midfoot score was improced from preoperative 45.6±5.3 to postoperative 82.5±7.4 (t=3.214,P< 0.01).

CONCLUSIONFor the painful accessory navicular bone of type II in adults, if the patient has a large navicular bone and not complicated with rigid flatfoot, once the conservative treatment fails, fusion of the primary and accessory naviculars may be a successful intervention. Overall, the procedure provides reliable pain relief, definite foot function improvement, and good patient satisfaction.