Evaluation of Posterior Ankle Pain in the Ballet Dancer
Dr. Pamela Luk MD, Dr. David Thordarson MD, Dr. Timothy Charlton MD
University of Southern California, Keck School of Medicine, Los Angeles CA
Foot and ankle injuries in the dancer are almost inevitable occurrences. Every dancer has self-treated his or her own share of blisters and bruised toenails, and other injuries unique to this art form. Posterior ankle pain is a common complaint in dancers, and the differential diagnosis often extends beyond the diagnosis of Achilles tendinosis. There are multiple structures in the posterior ankle and almost all of them have the potential to be the source of pain. The differential diagnosis of posterior ankle pain, from lateral to medial, is peroneal tendon subluxation/tendinitis, flexor hallucis longus tendinitis, posterior impingement syndrome with painful os trigonum\triogonal process, posterior talus osteochondritis dissecans, and posterior tibial tendonitis. The orthopaedist utilizes a combination of clinical presentation, physical exam, and diagnostic imaging to differentiate between these different causes of posterior ankle pain in order to develop an effective treatment plan for the dancer. We will discuss the aspects and differential diagnosis specific to the dancer and dance activities. For the purposes of this paper, we will begin this discussion laterally.
Peroneal tendon subluxation - Peroneal tendon subluxation is an uncommon ankle injury that is often misdiagnosed as a lateral ankle sprain. The two peroneal tendons, longus and brevis, run along the lateral aspect of the leg and normally sit in a sulcus behind the distal fibula. The depth of the sulcus is increased with a cartilaginous ridge and additionally a lateral bony ridge, which is present in about 70% of the population. The superior peroneal retinaculum is essential in maintaining the tendons behind the fibula. Subluxation, or the anterior slippage of the peroneus longus tendon out of the groove, occurs when the superior peroneal retinaculum is traumatically avulsed off the fibula alone, with the cartilaginous ridge, or with the cartilaginous ridge plus a rim of fibular bone. The most common mechanism of injury is skiing in which there is a sudden dorsiflexion stress to the ankle with a forceful reflexive eversion of the foot by the peroneal tendons. Peroneal tendon subluxation is a rare injury in dance although the disorder was initially described in a ballet dancer in 1803. A dancer may comment about a snapping sensation during completion of a tendu or a transition out of plié. Acutely, peroneal tendon subluxation presents with lateral ankle swelling and bruising, but unlike an ankle sprain, the symptoms are more prominent along the posterior fibular border and less anteriorly. Attempted eversion of the foot against resistance is the provocative maneuver to recreate the symptoms and support the diagnosis. In chronic cases making the diagnosis can be more difficult as the lateral ankle may be painless but have the sensation of recurrent snapping or popping and instability. The most important aspect of this diagnosis is the combination of the subjective complaints of the patient and the isolation of the symptoms to directly behind the fibula on physical exam. Ankle radiographs are obtained to evaluate for a rim fracture of the distal fibula. X-rays may appear normal but if your orthopaedist still has high suspicion with equivocal exam findings, an MRI may be recommended to assess the condition of the retinaculum and location of the tendons. Acute subluxations can be treated conservatively with immobilization in a splint or cast with no weight bearing on the injured ankle for six weeks or with surgery to repair the superior peroneal retinaculum. However, chronic subluxations do not do well with nonoperative treatment and should be addressed with surgery. A variety of procedures are available including repair or reconstruction of the retinaculum, groove deepening, construction of new bone blocks, and rerouting of normal ligaments but have the same goal of constraining the peroneal tendons to prevent redislocation. Postoperatively, one can expect to be weight bearing as tolerated in a short leg cast or boot for 4-6 weeks and then a stirrup brace for several additional weeks. After a rehabilitation program, return to unrestricted dancing can start 4 to 6 months after surgery.
Posterior impingement syndrome – Posterior impingement is the result of weight bearing on the ankle in maximal plantar flexion. It can often be associated with an os trigonum, an un-united lateral tubercle of the posterior talus, and sometimes with soft tissue entrapment. It is often seen in combination with FHL tendonitis, and differentiation between these two diagnoses is often extremely difficult. In most people and most dancers, an os trigonum is asymptomatic. In ballet dancers, it may be symptomatic but the degree of symptoms may not be related to the size of the os trigonum. Typically, the syndrome presents as posterolateral ankle pain in positions of maximal plantarflexion like tendús, frappés, and relevés that bring the calcaneus up against the posterior distal tibia and sandwich the os trigonum in between.
Dr. Pamela Luk MD, Dr. David Thordarson MD, Dr. Timothy Charlton MD
University of Southern California, Keck School of Medicine, Los Angeles CA
Foot and ankle injuries in the dancer are almost inevitable occurrences. Every dancer has self-treated his or her own share of blisters and bruised toenails, and other injuries unique to this art form. Posterior ankle pain is a common complaint in dancers, and the differential diagnosis often extends beyond the diagnosis of Achilles tendinosis. There are multiple structures in the posterior ankle and almost all of them have the potential to be the source of pain. The differential diagnosis of posterior ankle pain, from lateral to medial, is peroneal tendon subluxation/tendinitis, flexor hallucis longus tendinitis, posterior impingement syndrome with painful os trigonum\triogonal process, posterior talus osteochondritis dissecans, and posterior tibial tendonitis. The orthopaedist utilizes a combination of clinical presentation, physical exam, and diagnostic imaging to differentiate between these different causes of posterior ankle pain in order to develop an effective treatment plan for the dancer. We will discuss the aspects and differential diagnosis specific to the dancer and dance activities. For the purposes of this paper, we will begin this discussion laterally.
Peroneal tendon subluxation - Peroneal tendon subluxation is an uncommon ankle injury that is often misdiagnosed as a lateral ankle sprain. The two peroneal tendons, longus and brevis, run along the lateral aspect of the leg and normally sit in a sulcus behind the distal fibula. The depth of the sulcus is increased with a cartilaginous ridge and additionally a lateral bony ridge, which is present in about 70% of the population. The superior peroneal retinaculum is essential in maintaining the tendons behind the fibula. Subluxation, or the anterior slippage of the peroneus longus tendon out of the groove, occurs when the superior peroneal retinaculum is traumatically avulsed off the fibula alone, with the cartilaginous ridge, or with the cartilaginous ridge plus a rim of fibular bone. The most common mechanism of injury is skiing in which there is a sudden dorsiflexion stress to the ankle with a forceful reflexive eversion of the foot by the peroneal tendons. Peroneal tendon subluxation is a rare injury in dance although the disorder was initially described in a ballet dancer in 1803. A dancer may comment about a snapping sensation during completion of a tendu or a transition out of plié. Acutely, peroneal tendon subluxation presents with lateral ankle swelling and bruising, but unlike an ankle sprain, the symptoms are more prominent along the posterior fibular border and less anteriorly. Attempted eversion of the foot against resistance is the provocative maneuver to recreate the symptoms and support the diagnosis. In chronic cases making the diagnosis can be more difficult as the lateral ankle may be painless but have the sensation of recurrent snapping or popping and instability. The most important aspect of this diagnosis is the combination of the subjective complaints of the patient and the isolation of the symptoms to directly behind the fibula on physical exam. Ankle radiographs are obtained to evaluate for a rim fracture of the distal fibula. X-rays may appear normal but if your orthopaedist still has high suspicion with equivocal exam findings, an MRI may be recommended to assess the condition of the retinaculum and location of the tendons. Acute subluxations can be treated conservatively with immobilization in a splint or cast with no weight bearing on the injured ankle for six weeks or with surgery to repair the superior peroneal retinaculum. However, chronic subluxations do not do well with nonoperative treatment and should be addressed with surgery. A variety of procedures are available including repair or reconstruction of the retinaculum, groove deepening, construction of new bone blocks, and rerouting of normal ligaments but have the same goal of constraining the peroneal tendons to prevent redislocation. Postoperatively, one can expect to be weight bearing as tolerated in a short leg cast or boot for 4-6 weeks and then a stirrup brace for several additional weeks. After a rehabilitation program, return to unrestricted dancing can start 4 to 6 months after surgery.
Posterior impingement syndrome – Posterior impingement is the result of weight bearing on the ankle in maximal plantar flexion. It can often be associated with an os trigonum, an un-united lateral tubercle of the posterior talus, and sometimes with soft tissue entrapment. It is often seen in combination with FHL tendonitis, and differentiation between these two diagnoses is often extremely difficult. In most people and most dancers, an os trigonum is asymptomatic. In ballet dancers, it may be symptomatic but the degree of symptoms may not be related to the size of the os trigonum. Typically, the syndrome presents as posterolateral ankle pain in positions of maximal plantarflexion like tendús, frappés, and relevés that bring the calcaneus up against the posterior distal tibia and sandwich the os trigonum in between.
Several key components of history are key with this diagnosis. Posterior impingement syndrome is most painful upon completion and maintenance of the en pointe position. Posterior impingement syndrome should not hurt in plié, or from the transition of a neutral stance into en pointe position. Patients will often report the sensation of being “locked out” of completing en pointe position. On physical exam, the diagnosis is confirmed by localized tenderness behind the peroneal tendons and by painful passive forced plantarflexion of the ankle or relevé en pointe that recreates the impingement. Additionally, temporary pain relief with a lidocaine injection into the soft tissues behind the peroneal tendons supports the diagnosis. (INSERT IMAGE INJECTION) This is generally done with ultrasound or fluoroscopic guidance, to avoid inadvertent injection of the FHL tendon, and subsequent misdiagnosis. Evaluation also includes ankle radiographs and an additional lateral view of the ankle in full plantarflexion or en pointe to identify the os trigonum. More advanced imaging studies are not usually required. In the case of a painful trigonal process, a bone scan may show increased uptake, suggestive of a trigonal process stress fracture. Treatment should start with modification of activities, physical therapy, and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen in skeletally mature dancers. Of key importance is to refrain from proceeding directly to surgery as the condition is over diagnosed and leads to unnecessary operations. Pain improvement is gradual and one can expect healing time to be the same as the duration of pain before the initiation of treatment. When conservative management fails or symptoms recur, fluoroscopic injection of long and short acting corticosteroids, potent anti-inflammatory medications, especially if the lidocaine injection was effective, can be helpful.
Most os trigona are not surgical problems but if pain and disability persist in the serious dancer, one can proceed with elective excision of the os through a posterolateral open approach or arthroscopic excision. Postoperatively, weight bearing as tolerated can begin as soon as one week after surgery with a gradual increase in exercise intensity and the goal of returning to full dancing in 3 months.
FHL Tendinitis - Tendinitis of the flexor hallucis longus (FHL) is so common in the dancer that it is known as dancer’s tendinitis. The FHL tendon is responsible for flexion of the great toe at the interphalangeal joint and plantarflexion of the foot at the ankle. It passes through a fibro-osseous tunnel from the posterior talus along the medial aspect of the hindfoot and then on to the plantar surface of the foot. When the tendon is strained it may not be able to move smoothly in the tunnel, which can lead to irritation, swelling and subsequently further binding of the tendon. Triggering, a catching of the tendon that prevents smooth flexion and extension, of the great toe can occur if there is a nodule or partial tear in the tendon. Complete immobility of the tendon in its tunnel can cause total loss of toe flexion and extension, also known as pseudohallux rigidus. FHL tendinitis can present with posteromedial tenderness directly behind the medial malleolus of the ankle or sometimes arch pain under the base of the first metatarsal where the FHL tendon crosses the flexor digitorum longus tendon, which flexes the lesser toes. Active relevés and deep pliés recreate the pain as the inflamed tendon is forced to slide in its sheath. Passive motion of the great toe may also reproduce symptoms. A dancer will complain of tenderness during the transition up into en pointe position, but not necessarily pain once en pointe position is reached and maintained. Patient history and the exam are often diagnostic, but radiographs may be ordered to rule out a fracture, subtalar coalition, or concomitant symptomatic os trigonum. An MRI is not needed to make the diagnosis, but may help to evaluate the degree of tendon injury, particularly longitudinal split tears of the FHL. Initially conservative treatment is usually effective and consists of rest, ice, elevation, compression, and modified activity including refraining from pointe work. NSAIDs again are helpful as anti-inflammatory agents but should not be taken just as a painkiller to allow for continued dancing. The patient must enter a period of “true rest” with all barre work stopped. If conservative management is ineffective, ultrasound guided injection of the FHL tendon sheath with a 3cc mixture of lidocaine and corticosteroid can be diagnostic, and in 50% of the cases, therapeutic. If the tendinitis is recurrent or disabling, operative treatment to release the tendon sheath can be considered. Release is performed through a medial incision, with careful posterior retraction of the neurovascular bundle so as not to damage the calcaneal branch of the tibial nerve.
FHL Tendinitis - Tendinitis of the flexor hallucis longus (FHL) is so common in the dancer that it is known as dancer’s tendinitis. The FHL tendon is responsible for flexion of the great toe at the interphalangeal joint and plantarflexion of the foot at the ankle. It passes through a fibro-osseous tunnel from the posterior talus along the medial aspect of the hindfoot and then on to the plantar surface of the foot. When the tendon is strained it may not be able to move smoothly in the tunnel, which can lead to irritation, swelling and subsequently further binding of the tendon. Triggering, a catching of the tendon that prevents smooth flexion and extension, of the great toe can occur if there is a nodule or partial tear in the tendon. Complete immobility of the tendon in its tunnel can cause total loss of toe flexion and extension, also known as pseudohallux rigidus. FHL tendinitis can present with posteromedial tenderness directly behind the medial malleolus of the ankle or sometimes arch pain under the base of the first metatarsal where the FHL tendon crosses the flexor digitorum longus tendon, which flexes the lesser toes. Active relevés and deep pliés recreate the pain as the inflamed tendon is forced to slide in its sheath. Passive motion of the great toe may also reproduce symptoms. A dancer will complain of tenderness during the transition up into en pointe position, but not necessarily pain once en pointe position is reached and maintained. Patient history and the exam are often diagnostic, but radiographs may be ordered to rule out a fracture, subtalar coalition, or concomitant symptomatic os trigonum. An MRI is not needed to make the diagnosis, but may help to evaluate the degree of tendon injury, particularly longitudinal split tears of the FHL. Initially conservative treatment is usually effective and consists of rest, ice, elevation, compression, and modified activity including refraining from pointe work. NSAIDs again are helpful as anti-inflammatory agents but should not be taken just as a painkiller to allow for continued dancing. The patient must enter a period of “true rest” with all barre work stopped. If conservative management is ineffective, ultrasound guided injection of the FHL tendon sheath with a 3cc mixture of lidocaine and corticosteroid can be diagnostic, and in 50% of the cases, therapeutic. If the tendinitis is recurrent or disabling, operative treatment to release the tendon sheath can be considered. Release is performed through a medial incision, with careful posterior retraction of the neurovascular bundle so as not to damage the calcaneal branch of the tibial nerve.
Posterior impingement syndrome may be present concurrently with FHL tendinitis as the tendon runs just medial to an os, so os excision can be performed at the same time via a posterolateral incision. Careful attention is made to inspect the FHL tendon tear, which can occur in about 10% of patients. Postoperatively, weight bearing on the injured ankle can begin when the surgical wound is healed. Physical therapy and early ankle range of motion are encouraged. Recovery time is about 6-8 weeks for tendon treatment alone and 12 weeks if combined with os trigonum excision. Prognosis and rehabilitation is delayed in the case of FHL tear. Disappointment can arise after surgery if there are unrealistic goals; keep in mind that the surgery is pain relieving but does not improve the degree of ankle plantarflexion.
Posterior OCD - Posterior talus osteochondritis dissecans (OCD) lesion is an intraarticular fracture of the talar dome that extends from the articular surface to the underlying bone that has suboptimal blood supply. The fracture may be the result of a single, large trauma, repeated micro trauma, or no trauma at all. If the fracture does not heal, the fragment will become ischemic, then necrotic and result in bony collapse which subjects the area to abnormal, elevated mechanical stress upon weight bearing. Posterior talar OCD lesions exist in medial and lateral varieties; medial lesions are more common and tend to be more posterior, deeper, nondisplaced, and less likely related to trauma. They may be identified immediately following ankle injury but are more often associated with chronic ankle pain of unknown origin. Suspicion of an OCD lesion should be raised with recurrent ankle swelling, stiffness, weakness, and a sensation of giving way without a clear mechanism of injury. In the dancer, pain may occur at termination of en pointe, and can often present similarly to a painful os trigonum. The clinical exam is relatively normal, but ankle radiographs will usually be indicative. Advanced imaging is also beneficial in this situation to determine the severity of the lesion which affects treatment options – MRIs are recommended in cases of chronic ankle pain of unclear etiology whereas CTs are better when the lesion is visible on the x-rays. For a less severe stage of disease or in skeletally immature patients, a trial period of conservative management with immobilization and nonweightbearing is reasonable. For more severe stages of disease, multiple factors regarding the fragment are assessed before deciding the appropriate surgery. Operative interventions can be categorized as 1) primary repair (retention of fragment and stable fixation to allow for fracture healing), 2) palliative (arthroscopic irrigation of the ankle joint to remove loose bone fragments but damaged cartilage is neither repaired nor replaced), 3) reparative (drilling or microfracture technique of the bone marrow underlying the lesion to stimulate stem cells to generate a fibrous clot that fills the defect but is not normal articular cartilage), and 4) restorative (treatment of large, full thickness cartilage loss by transplanting cartilage and bone graft either from a cadaver or from one’s self or harvesting autologous cartilage cells grown in vitro and then reimplanted into the lesion defect). After operative treatment, early range of motion and strengthening exercises are started but weight bearing on the ankle is delayed 3-6 weeks, depending on the extent of the procedure. Differentiation of posterior OCD and painful os trigonum is essential. Posterior OCD lesions have a poor prognosis in the dance population.
Posterior tibial tendinitis - Posterior tibial tendinitis is inflammation of the posterior tibial tendon, which is key in stabilizing the subtalar joint for normal heel push off. However, it is rare in dancers and more frequently plagues athletes who move with rapid changes in direction on a well-planted foot that places increased stress on the tendon. Dancers will often complain of medial tenderness in plié or medial pain when landing in a jete. PT tendinitis presents with pain around the medial aspect of the ankle, usually inferior and posterior to the medial malleolus and sometimes even includes the medial hindfoot. Symptoms are aggravated by weight bearing activities. The exam will demonstrate swelling and tenderness along the distal tendon from the medial malleolus to the tendon’s insertion on the medial midfoot, exacerbation of pain with active inversion and eversion of the subtalar joint against resistance, and possible sagging of the arch upon standing. Careful attention is made to 5th position, forced turnout, and sickling. Radiographs of the foot and ankle are taken to rule out other processes like an accessory navicular or a stress fracture. MRIs are not usually needed for diagnosis but may be ordered to differentiate between tendinitis and partial or complete tendon ruptures. Like FHL tendinitis, initial treatment is conservative and medication is both anti-inflammatory and pain relieving. Avoid steroid injections. A medial arch orthotic is used to offload the tendon, and if more immobilization is needed, a walking cast or boot is recommended for 4-6 weeks. If there is no improvement in symptoms following 3-6 months of conservative management, surgery can be considered. Intraoperatively, the posterior tibial tendon and surrounding ligaments are explored, inflamed or scarred tissue removed, and tendon reinforced with tendon graft locally, if needed. Postoperatively, even with early rehabilitation therapy, return to full athletic activity may take 4-12 months. Despite best medical and surgical management, the prognosis is guarded for return to full dance activities.
These have been typical presentations and acceptable methods of management for these five causes of posterior ankle pain, but they are by no means representative of all cases. Aside from gaining a more knowledgeable awareness of an ankle injury, a dancer must also know when it is time to seek orthopaedic help. Location of pain is the key in diagnosis and discussion of the positions of dance that cause the pain will aid in the challenging diagnosis of posterior ankle pain in the dancer.
References
Posterior OCD - Posterior talus osteochondritis dissecans (OCD) lesion is an intraarticular fracture of the talar dome that extends from the articular surface to the underlying bone that has suboptimal blood supply. The fracture may be the result of a single, large trauma, repeated micro trauma, or no trauma at all. If the fracture does not heal, the fragment will become ischemic, then necrotic and result in bony collapse which subjects the area to abnormal, elevated mechanical stress upon weight bearing. Posterior talar OCD lesions exist in medial and lateral varieties; medial lesions are more common and tend to be more posterior, deeper, nondisplaced, and less likely related to trauma. They may be identified immediately following ankle injury but are more often associated with chronic ankle pain of unknown origin. Suspicion of an OCD lesion should be raised with recurrent ankle swelling, stiffness, weakness, and a sensation of giving way without a clear mechanism of injury. In the dancer, pain may occur at termination of en pointe, and can often present similarly to a painful os trigonum. The clinical exam is relatively normal, but ankle radiographs will usually be indicative. Advanced imaging is also beneficial in this situation to determine the severity of the lesion which affects treatment options – MRIs are recommended in cases of chronic ankle pain of unclear etiology whereas CTs are better when the lesion is visible on the x-rays. For a less severe stage of disease or in skeletally immature patients, a trial period of conservative management with immobilization and nonweightbearing is reasonable. For more severe stages of disease, multiple factors regarding the fragment are assessed before deciding the appropriate surgery. Operative interventions can be categorized as 1) primary repair (retention of fragment and stable fixation to allow for fracture healing), 2) palliative (arthroscopic irrigation of the ankle joint to remove loose bone fragments but damaged cartilage is neither repaired nor replaced), 3) reparative (drilling or microfracture technique of the bone marrow underlying the lesion to stimulate stem cells to generate a fibrous clot that fills the defect but is not normal articular cartilage), and 4) restorative (treatment of large, full thickness cartilage loss by transplanting cartilage and bone graft either from a cadaver or from one’s self or harvesting autologous cartilage cells grown in vitro and then reimplanted into the lesion defect). After operative treatment, early range of motion and strengthening exercises are started but weight bearing on the ankle is delayed 3-6 weeks, depending on the extent of the procedure. Differentiation of posterior OCD and painful os trigonum is essential. Posterior OCD lesions have a poor prognosis in the dance population.
Posterior tibial tendinitis - Posterior tibial tendinitis is inflammation of the posterior tibial tendon, which is key in stabilizing the subtalar joint for normal heel push off. However, it is rare in dancers and more frequently plagues athletes who move with rapid changes in direction on a well-planted foot that places increased stress on the tendon. Dancers will often complain of medial tenderness in plié or medial pain when landing in a jete. PT tendinitis presents with pain around the medial aspect of the ankle, usually inferior and posterior to the medial malleolus and sometimes even includes the medial hindfoot. Symptoms are aggravated by weight bearing activities. The exam will demonstrate swelling and tenderness along the distal tendon from the medial malleolus to the tendon’s insertion on the medial midfoot, exacerbation of pain with active inversion and eversion of the subtalar joint against resistance, and possible sagging of the arch upon standing. Careful attention is made to 5th position, forced turnout, and sickling. Radiographs of the foot and ankle are taken to rule out other processes like an accessory navicular or a stress fracture. MRIs are not usually needed for diagnosis but may be ordered to differentiate between tendinitis and partial or complete tendon ruptures. Like FHL tendinitis, initial treatment is conservative and medication is both anti-inflammatory and pain relieving. Avoid steroid injections. A medial arch orthotic is used to offload the tendon, and if more immobilization is needed, a walking cast or boot is recommended for 4-6 weeks. If there is no improvement in symptoms following 3-6 months of conservative management, surgery can be considered. Intraoperatively, the posterior tibial tendon and surrounding ligaments are explored, inflamed or scarred tissue removed, and tendon reinforced with tendon graft locally, if needed. Postoperatively, even with early rehabilitation therapy, return to full athletic activity may take 4-12 months. Despite best medical and surgical management, the prognosis is guarded for return to full dance activities.
These have been typical presentations and acceptable methods of management for these five causes of posterior ankle pain, but they are by no means representative of all cases. Aside from gaining a more knowledgeable awareness of an ankle injury, a dancer must also know when it is time to seek orthopaedic help. Location of pain is the key in diagnosis and discussion of the positions of dance that cause the pain will aid in the challenging diagnosis of posterior ankle pain in the dancer.
References
- Coughlin MJ, Schon LC: Disorders of Tendons. Chapter 22, Surgery of the Foot and Ankle, Coughlin MJ, Mann RA, Saltzman CL, eds: 1209- 1220, 2007.
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- McGarvey W, Clanton T: Peroneal tendon dislocations. Foot Ankle Clin 1:325-342, 1996.
- Hamilton WG, Bauman PA: Foot and Ankle Injuries in Dancers. Chapter 28, Surgery of the Foot and Ankle, Coughlin MJ, Mann RA, Saltzman CL, eds: 1628-1634.
- Hamilton WG: “Dancer’s tendinitis” of the FHL tendon. Presented at the Second Annual meeting of the American Orthopaedic Society for Sports Medicine, Durango, Colorado, July 11-14, 1976.
- Hamilton WG: Stenosing tenosynovitis of the flexor hallucis longus tendon and posterior impingement upon the os trigonum in ballet dancers. Foot Ankle 3: 74-80, 1982.
- Hamilton WG: Foot and ankle injuries in dancers. Clin Sports Med 7: 143-173, 1988.
- Sanhudo JA: Stenosing tenosynovitis of the flexor hallucis longus tendon at the sesamoid area. Foot Ankle Int 19(6): 356-362, 1998.
- Hamilton WG, Geppert MJ, Thompson FM: Pain in the posterior aspect of the ankle in dancers: Differential diagnosis and operative treatment. J Bone Joint Surg Am 78(10):1491-1500, 1996.
- Ferkel RD, Hommen JP: Arthroscopy of the Ankle and Foot. Chapter 29, Surgery of the Foot and Ankle, Coughlin MJ, Mann RA, Saltzman CL, eds: 1667-1677.
- Berndt AL, Harty M: Transchondral fractures (osteochondritis dissecans) of the talus. J Bone Joint Surg Am 41: 988-1020, 1959.
- McGarvey W, Clanton TO: Athletic Injuries to the Soft Tissues of the Foot and Ankle. Chapter 26, Surgery of the Foot and Ankle, Coughlin MJ, Mann RA, Saltzman CL, eds: 1513-1515, 2007.
- Gazdak AR, Cracchiolo A III: Rupture of the posterior tibial tendon: Evaluation of injury of the spring ligament and clinical assessment of tendon transfer and ligament repair. J Bone Joint Surg Am 79:675-681, 1997.