A surgical approach for flexible flatfeet in adults including a subtalar arthroereisis with the MBA sinus tarsi implant

Background: The purpose of this study was to determine the functional outcomes and radiographic results of adult patients who had an operation for flexible flatfeet without any hind-foot osteotomies or fusions. Methods: Twenty-eight feet in 23 patients with problems caused by their flexible flatfoot deformities had reconstructive foot and ankle surgery that included a subtalar arthroereisis (the restriction of the range of motion of a joint) with the Maxwell-Brancheau Arthroereisis (MBA) sinus tarsi implant. The American Orthopedic Foot and Ankle Society (AOFAS) Hindfoot Scale and a patient assessment questionnaire were obtained from all patients before surgery and at final follow-up. Preoperative and postoperative standing radiographs were analyzed to determine radiographic correction of the deformities. The average followup was 44 months. The MBA implant was surgically removed in 11 of 28 feet (39%) because of sinus tarsi pain. Results: The average preoperative AOFAS score was 52 and had improved to 87 (p < 0.00001) at final followup. The average response to four of five questions in the patient assessment had significantly improved (P < 0.05). On a 10-point scale, average patient satisfaction was 8.3 points; 78% said that they would have the surgery again. Correction after surgery was significant (p < 0.0001) in each of the three radiographic parameters evaluated for 'correction with MBA' and 'final correction.' With the numbers available, no significant differences could be detected after the MBA was removed. Complications included sinus tarsi pain in 46% (13) of the 28 feet in this study; after implant removal, 73% (8) of 11 feet had less discomfort than before surgery with AOFAS scores 80 or better. Conclusions: Reconstructive foot and ankle surgery that included a subtalar arthroereisis with the MBA sinus tarsi implant resulted in favorable clinical outcomes and patient satisfaction in 78% (18) of 23 patients. In spite of the high incidence of temporary sinus tarsi pain until the implant was removed, this operative approach compares favorably with other operations for flexible flatfoot deformities in adults.