Abstract
Stenosing tenosynovitis of the flexor hallucis longus (FHL) tendon is known as a major overuse lesion in female dancers. We describe arthroscopic surgical techniques in relation to the dynamic pathology of the disease. Crepitus and pain on moving the great toe with the ankle in plantar flexion on preoperative examination confirm the diagnosis of FHL stenosing tenosynovitis even if the os trigonum is not evident. The ankle is approached through standard posterolateral and posteromedial portals. A 4.0-mm-diameter 30° arthroscope is used. Soft tissues around the talus are cleared with a motorized shaver and a radiofrequency device. The posterior aspects of the talus, os trigonum, and FHL tendon surrounded by the tendon sheath are visualized. The dynamic pathology of the FHL tendon is well observed on passive motion of the great toe. The prominent bone fragment of the talus is removed and the tendon sheath is cut with a retrograde knife and a motorized shaver from the superior border down to the entrance of the fibro-osseous tunnel. Arthroscopic release of the FHL tendon sheath is a useful and easy method to directly approach the dynamic pathology of FHL tenosynovitis in female ballet dancers.
Since the 2-portal endoscopic approach with posterolateral and posteromedial ports was first described by van Dijk et al.1 in 2000, arthroscopic treatment for posterior ankle impingement syndrome in athletes has been widely applied.2, 3, 4, 5, 6 The syndrome is typically seen in female ballet dancers, as well as occasionally in soccer players,1, 2, 6, 7, 8, 9, 10 and is usually manifested by posterior ankle pain. However, the pain, although characteristic, can have various causes. An os trigonum and a hypertrophic posterior talar process (Steida process) mainly contribute to the posterior ankle pain due to impingement between the posterior aspect of the tibia and the calcaneus. Soft-tissue impingement can also be responsible for the pain. In female ballet dancers, stenosing tenosynovitis of the flexor hallucis longus (FHL) combined with an os trigonum has been reported as a major pathologic finding, possibly due to the strenuous en pointe position.1, 6, 8, 9, 10 However, only a few reports are available on detailed surgical techniques directly addressing the dynamic pathology of the disease.1, 4, 5, 6 Similarly, postoperative treatment until the ballet dancers accomplish en pointe performance has not been extensively studied. We describe the dynamic pathology of FHL lesions based on arthroscopic findings and the surgical technique of FHL tendon sheath release, as well as the postoperative course including performance ability, in female ballet dancers operated on for FHL tenosynovitis.
Preoperative Evaluation
Patients complain of posterior ankle pain while standing with their ankle in extreme plantar flexion, as in the en pointe position. When they move the great toe with the ankle in plantar flexion, the pain increases and crepitus and a moving nodule become palpable at the posteromedial portion behind the medial malleolus. A local anesthetic or corticosteroid injection under ultrasound guidance can be given to confirm the diagnosis of stenosing tendinitis. A lateral-view plain radiograph often shows the os trigonum and its relation to the talus; however, the os trigonum is not always evident on plain radiographs (Fig 1A). Computed tomography shows the precise location, size, and shape of the os trigonum and the posterior talar process (Fig 1B). T2-weighted fat-suppressed or short tau inversion recovery magnetic resonance images show thickening and tenosynovitis of the FHL tendon and fluid collection around the FHL tendon (Fig 2). They can also facilitate detection of bone marrow edema within or around the os trigonum or the Steida process and posterior capsular thickening. Conservative treatment including physical therapy and corticosteroid injections into the sheath of the FHL tendon under ultrasound assistance are usually attempted. If patients are not able to perform at a satisfactory level despite a minimum of 3 months of conservative treatment, arthroscopic surgery is indicated.
Fig 1.
Right ankle joint in a 17-year-old ballet dancer preoperatively. (A) An os trigonum is not evident on the lateral radiograph. (B) The lateral computed tomography image shows an unremarkable os trigonum connected to the posterior aspect of the talus (arrow).
Fig 2.
(A) Sagittal and (B) axial short tau inversion recovery magnetic resonance images show tenosynovitis and fluid collection around the flexor hallucis longus tendon (arrows).
Surgical Technique
The operation is performed with the patient under general anesthesia in the prone position (Table 1). After attachment of a pneumatic cuff, 5 mL of normal saline solution is injected into the subtalar joint posterolaterally. The posterolateral portal is first established 1 cm proximally to the tip of the distal lateral malleolus and immediately adjacent to the Achilles tendon. Blunt dissection to the level of the posterior subtalar joint is carried out with a small mosquito clamp before insertion of the instruments.
Table 1.
Surgical Steps and Technical Tips
| Surgical Steps | Technical Tips |
|---|---|
| Preparation | A 4.0-mm-diameter 30° arthroscope and fluoroscope are used. |
| Saline solution is injected into the subtalar joint. | |
| Insertion of arthroscope | A posterolateral portal is used as the viewing portal and a posteromedial portal as the working portal; the portals can be easily switched. |
| A motorized shaver is inserted such that the tip of the shaver is located between the arthroscope and the talus. | |
| When it is difficult to determine whether the arthroscope is inserted correctly, its position and direction should be confirmed by fluoroscopy. | |
| Debridement of soft tissue | The soft tissue between the talus and the Achilles tendon is removed with a motorized shaver, and synovitis-affected tissue is shaved with a radiofrequency system. |
| Identification of FHL tendon | The FHL is usually found 1-2 cm proximally to the subtalar joint. |
| If it is difficult to find the FHL tendon because of synovitis, passive motion of the great toe may help identify the FHL tendon. | |
| Resection of os trigonum | Adhesions between the bone and the tendon sheath are resected with a small punch. |
| Examination of FHL tendon | The great toe is moved passively to examine the FHL tendon pathology. |
| The tendon may be entrapped under the sheath, and sometimes, a partial tear of the tendon is found. | |
| Release of tendon sheath | The thick tendon sheath is cut with a retrograde knife from the superior border of the sheath while the tendon structure is protected. |
| Repair of FHL tendon | When fibrillation or a partial tear of the tendon is found, the tendon surface is smoothed with a radiofrequency system. |
| Confirmation of release | Release of the FHL tendon sheath is confirmed along the entire tendon down to the entrance of the fibro-osseous tunnel with passive motion of the ankle and great toe. |
FHL, flexor hallucis longus.
A 4.0-mm-diameter 30° arthroscope (True View II; Olympus, Tokyo, Japan) is inserted from the posterolateral portal to reach the posterior aspect of the talus. When it is difficult to determine whether the arthroscope is inserted correctly, its position and direction should be confirmed with fluoroscopy. Next, a posteromedial portal is established just medially to the Achilles tendon and parallel with the posterolateral portal. A motorized shaver (3.5-mm cutter; Stryker, Kalamazoo, MI) is inserted from the posteromedial portal such that the tip of the shaver is located between the arthroscope and the posterior aspect of the talus. Soft tissues between the talus and the Achilles tendon are removed with the shaver (Video 1). Synovitis-affected tissue is shaved with a radiofrequency system (VAPR; DePuy Mitek, Raynham, MA). The posterior aspect of the talus or os trigonum (if it exists) is then visualized (Fig 3A). The soft tissue and posterior capsule of the subtalar joint are removed along the posterior aspect of the talus to locate the FHL tendon, which is usually found 1 to 2 cm proximally to the subtalar joint (Fig 3B). If finding the FHL tendon is difficult because of synovitis, passive motion of the great toe may help in its identification. Because the retinaculum at this portion is edematous and thin, it can be easily resected with the shaver. The FHL tendon serves as an important landmark to prevent damage to the more medially located neurovascular bundle. The FHL tendon surrounded by a thick tendon sheath (Fig 3B), posterior aspect of the talus (os trigonum), and superior articular surface of the calcaneus are well visualized. Adhesions surrounding the FHL tendon often can be observed, and detachment of the sheath from the talar process is performed. The os trigonum or hypertrophic bone of the posteromedial aspect of the talus is resected with a small punch to visualize the entire tendon sheath (Fig 4A). At this point, the great toe is moved passively to examine the pathology of the FHL. The tendon may be found entrapped under the sheath, and a partial tear of the tendon is sometimes noted (Fig 4B). The tendon sheath is cut with a knife (4-mm retrograde Arthro-Lok Blade; Beaver Visitec, Waltham, MA) from the superior border of the sheath while the tendon is protected (Fig 5A). When fibrillation or a partial tear of the tendon is found, the tendon surface is smoothed with a radiofrequency system (Fig 5B). The remaining sheath is easily removed with a small punch and motorized shaver. Then, the entire FHL tendon is well visualized on passive motion of the great toe; the narrow FHL tendon can be found under the sheath (Figs 6A and 7A). Release of the FHL tendon sheath is performed down to the entrance of the fibro-osseous tunnel (Figs 6B and 7B). The presence of possible entrapment along the entire tendon is confirmed with passive motion of the ankle and great toe. The intra-articular space is irrigated, and the portals are sutured.
Fig 3.
Arthroscopic views of posterior aspect of ankle and subtalar joint (prone position, right ankle, viewed from posterolateral portal). (A) After shaving of the soft tissues between the Achilles tendon and the talus, the posterior aspect of the os trigonum (OT) and the superior aspect of the calcaneus (C) are visualized. (B) Magnified view of the square in A. The flexor hallucis longus tendon surrounded by edematous retinaculum and synovium is identified on passive motion of the great toe. (Lat, lateral; Med, medial; S, synovium of flexor hallucis longus tendon.)
Fig 4.
Arthroscopic examination of os trigonum (OT) and flexor hallucis longus (FHL) tendon (prone position, right ankle, with arthroscopic view from posterolateral portal). (A) The OT and adhesion between the bone and the sheath are resected with a small punch. (B) A partial tear of the FHL tendon (arrow) is observed at the superior border of the tendon sheath (TS). (C, calcaneus.)
Fig 5.
Arthroscopic technique for release of flexor hallucis longus (FHL) tendon sheath and smoothing of tendon surface (prone position, right ankle, with arthroscopic view from posterolateral portal). (A) The tendon sheath is cut with a retrograde knife from the superior border of the sheath. (B) When fibrillation or a partial tear of the tendon is found (arrow), the tendon surface is smoothed with a radiofrequency device. (OT, os trigonum.)
Fig 6.
Arthroscopic view of flexor hallucis longus (FHL) tendon during release of tendon sheath (prone position, right ankle, with arthroscopic view from posterolateral portal). (A) A narrowed FHL tendon under the tendon sheath (arrow) is observed. (B) Release of the FHL tendon sheath is performed completely down to the entrance of the fibro-osseous tunnel (arrow).
Fig 7.
Arthroscopic examination after release of flexor hallucis longus (F) tendon sheath and resection of os trigonum in a 19-year-old female ballet dancer (prone position, right ankle, with arthroscopic view from posterolateral portal). (A) A narrowed flexor hallucis longus tendon under the sheath (arrow) is remarkable. (B) The entrance of the fibro-osseous tunnel (arrow) is clearly visualized. (C, calcaneus; T, talus.)
Postoperative Treatment and Return to Ballet Dancing
The ankle is immobilized with a bandage, and partial weight bearing (10 kg) is applied for 3 to 5 days. Full weight bearing is allowed 5 days after surgery, and postoperative rehabilitation is started. Range-of-motion exercises of the ankle joint are started 1 week after the operation, and proprioception exercises using a balance mat and muscle-strengthening exercises for the ankle and body trunk are allowed 2 weeks after surgery. Although calf-raise training is usually begun 4 weeks after surgery, the duration from surgery until the dancers accomplish en pointe is relatively longer.
Discussion
Stenosing tenosynovitis of the FHL tendon is one of the major causes of posterior ankle pain in female ballet dancers unless an os trigonum is evident.1, 3, 4, 5, 6, 8, 9, 10 Preoperative examination shows the characteristic symptom of crepitus at the posteromedial portion behind the medial malleolus; it is palpable and sometimes heard while the dancers move their great toes with their ankles in the plantar flexion position. Although relatively common in this group of athletes, stenosing tenosynovitis of the FHL tendon has been rarely addressed in the literature, and a detailed description of its dynamic pathology and arthroscopic technique–based treatment has not been extensively reported.4, 5, 6 The ability to perform in the en pointe position, necessary for ballet performance, has not been addressed in the literature either.
The advantages of arthroscopic surgery, as presented in this report, are good direct and dynamic visualization of FHL lesions and the minimal extent of surgical intervention. The dynamic pathology of FHL lesions can be easily understood and assessed especially on passive motion of the great toe during arthroscopy. The thick tendon sheath lies just near the medial aspect of the talar process or os trigonum and is usually entrapped and narrowed under the thick tendon sheath. Fraying and partial tearing of the FHL are often observed. A retrograde knife can be useful during resection of the thick tendon sheath and helps to prevent further tendon damage. The procedure can be quickly and safely performed if the surgeon is familiar with arthroscopic visualization.
Notwithstanding the aforementioned advantages, there are potential limitations and complications associated with the arthroscopic approach. It is extremely difficult to arthroscopically repair a ruptured tendon, and further improvements of the arthroscopic techniques to treat this condition seem necessary. Damage to the medial branch of the tibial nerve still remains an important complication. Because the nerve is located anteriorly and medially to the FHL, the shaver and radiofrequency device should not be used within the fat tissue beyond the FHL. Damage to the Achilles tendon is another complication that can possibly occur when the arthroscope is inserted from the portal, and careful palpation of the Achilles tendon before portal insertion may reduce the risk of damage (Table 2).
Table 2.
Pitfalls, Risks, and Benefits of Arthroscopic Release of FHL Tendon Sheath
| Pitfalls |
| A thorough preoperative physical examination is necessary if the os trigonum is not evident. |
| If the FHL tendon is remarkably damaged, arthroscopic repair is difficult. |
| Risks |
| Damage to medial branch of tibial nerve |
| Benefits |
| Good direct and dynamic visualization of FHL tendon pathology |
FHL, flexor hallucis longus.
Postoperative rehabilitation is an important part of the treatment process, and in ballet dancers with FHL tenosynovitis, the final goal is to regain the ability to perform en pointe. Exercises aimed to restore the range of motion, proprioception, coordination, and muscle strength of not only the ankle but also the trunk stabilizers should be incorporated early in the postoperative period to allow dancers to perform at the preinjury level. Arthroscopic release of the FHL tendon sheath can facilitate early return to daily and sport activities. The duration of recovery including en pointe performance varied in previous reports,1, 3, 4 and a correlation between the length of symptoms before surgery and return to training has been indicated.2, 4 Preoperative informed consent should include a sufficient explanation about the relatively long recovery time after surgery before full performance abilities become possible.
Footnotes
The authors report that they have no conflicts of interest in the authorship and publication of this article.
Supplementary Data
Arthroscopic release of the flexor hallucis longus (FHL) tendon sheath in the right ankle of a 17-year-old female ballet dancer. Although preoperative lateral radiographs and computed tomography images show an unremarkable os trigonum, sagittal and axial short tau inversion recovery (STIR) magnetic resonance images show tenosynovitis and fluid collection around the FHL tendon. The procedure is carried out using the 2 standard posterior portals with the patient in the prone position. The posterolateral portal is used as the viewing portal and the posteromedial portal as the working portal. After shaving of the soft tissues between the Achilles tendon and the talus, the posterior aspect of the os trigonum and the superior aspect of the calcaneus are visualized. The FHL tendon is identified on passive motion of the great toe. The dynamic pathology is well understood with passive motion of the ankle and the great toe during arthroscopy. The tendon sheath is cut with a retrograde knife from the superior border of the sheath down to the entrance of the fibro-osseous tunnel. When fibrillation or a partial tear of the tendon is found, the tendon surface is smoothed with a radiofrequency device.
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Associated Data
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Supplementary Materials
Arthroscopic release of the flexor hallucis longus (FHL) tendon sheath in the right ankle of a 17-year-old female ballet dancer. Although preoperative lateral radiographs and computed tomography images show an unremarkable os trigonum, sagittal and axial short tau inversion recovery (STIR) magnetic resonance images show tenosynovitis and fluid collection around the FHL tendon. The procedure is carried out using the 2 standard posterior portals with the patient in the prone position. The posterolateral portal is used as the viewing portal and the posteromedial portal as the working portal. After shaving of the soft tissues between the Achilles tendon and the talus, the posterior aspect of the os trigonum and the superior aspect of the calcaneus are visualized. The FHL tendon is identified on passive motion of the great toe. The dynamic pathology is well understood with passive motion of the ankle and the great toe during arthroscopy. The tendon sheath is cut with a retrograde knife from the superior border of the sheath down to the entrance of the fibro-osseous tunnel. When fibrillation or a partial tear of the tendon is found, the tendon surface is smoothed with a radiofrequency device.