Hindfoot Endoscopic Findings of Posterior Ankle Impingement Syndrome in Ballet Dancers (SS-56)

Introduction Posterior ankle pain is a common but serious problem in ballet dancers. Certain kinds of pathological conditions have been reported, such as os trigonum (OT) syndrome, fracture of the Stieda process, flexor hallucis longus (FHL) tendinosis and/or tenosynovitis, soft tissue impingement, and so on. They are considered as a pathological unit of posterior ankle impingement syndrome (PAIS). The purpose of this study is to elucidate the pathologies of PAIS and to clarify how to approach and treat these conditions. Methods Between September 2007 and August 2010, 35 feet of 32 patients, including only one foot of a male patient, underwent hindfoot endoscopic surgery due to PAIS. Average age was 19.6 years (range, 12-40) at the time of surgery. The pathological conditions were retrospectively analyzed mainly with operative findings, also referring with X-ray, MRI, and histological findings. Surgical technique presented by van Dijk was applied to all feet. Results Synchondrosis injury (SCI) was detected in 14 feet, synovitis associated with one or more movable os trigonum (mOT) in 12, a fracture (or microfracture) in os trigonum or posterior process of the talus in four, DJD beneath the OT in two. Injury to the FHL tendon matrix was observed in 23 feet, distal insertion of FHL muscle fibers in 12, and anomalous muscle (FDAL) in two. Intermalleolar ligament (IML), which is also called a tibial slip, a part of transverse tibiofibular ligament, or a pseudomeniscoid were found in 21 feet (60%), ranging from 1 to 5 mm in width. Among them, five were adherent to the FHL tendon sheath, and three had behavior linked with the FHL motion, which seemed to undergo posterior ankle impingement. Osteochondral lesion of the medial talar trochlea were observed in two feet, nodular fibrosis in posterior talocalcaneal ligament and marked synovitis in ankle and posterior subtalar joint in one, respectively. A great majority of feet were affected with two or more pathologic conditions, except four feet. 22 feet (62.9%) had combined bony impingement (SCI, mOT, fracture) with FHL tendon injury. Conclusion Bony impingement was the major pathological process, related in more than 90 percent of the patients; special attention, however, should be paid to some other conditions that concomitantly existed. The hindfoot arthroscopic approach has great diagnostic potentials to posterior aspect of ankle and posterior subtalar joint. And also enables to treat bony impingement, IML lesions, and tenolysis of the FHL and/or FDAL tendon. But when repair of the severely injured FHL tendonor extirpation of ganglions on the tendon sheath is necessary, the other approach should be considered.