The posterior part of the deltoid ligament integrates with the tendon sheath of the posterior tibial tendon (PTT), forming a fibrocartilaginous bed in the tendon sheath1,2. Deltoid ligament tears may involve this fibrocartilaginous complex and disrupt the septum between the ankle joint and the PTT sheath. Complete rupture of the deltoid ligament accompanying ankle fractures and/or syndesmotic injuries is usually treated surgically with repair of the fibrocartilaginous bed of the PTT. We report 3 patients with pinhole injuries to the fibrocartilaginous bed with partial tear of the posterior deltoid ligament without medial instability or syndesmotic instability of the ankle.
The patients were informed that data concerning their cases would be submitted for publication, and they provided consent.
Case Reports
Case 1
A 28-year-old male rugby player sprained his left ankle during forced dorsiflexion during rugby practice. The patient was treated conservatively using taping. He resumed physical training and rugby practice after 3 weeks of rest. However, he could not play satisfactorily in rugby games even 5 months after the injury because of pain and swelling in the posteromedial aspect of the ankle; thus, he was referred to our hospital.
The first examination revealed tenderness along PTT on the medial side of the left ankle. Medial and rotatory instabilities of the ankle were not detected either manually or radiographically. No fractures or diastasis of the syndesmosis were detected on routine or weight-bearing radiographs. Hydrocele in the tendon sheath and partial tear of the deltoid ligament were detected on magnetic resonance imaging (MRI) (Fig. 1).
Hydrocele (white arrows) was found in the posterior tibial tendon (PTT) sheath on the sagittal plane of magnetic resonance imaging (MRI). T2-weighted image (Fig. 1-A) and STIR image (Fig. 1-B).
The patient underwent arthroscopic and tendoscopic examinations 1 year after the injury at his request, after conclusion of the annual season of the Japan Rugby Top League. Ruptured ligament fibers and inflamed synovium were observed in the medial gutter of the ankle. Posterior tibial tendoscopy revealed fibrocartilaginous bed rupture of the tendon sheath and communication with the ankle joint space (Fig. 2). The ruptured fibrocartilaginous bed of PTT was repaired by an open procedure with a periosteal flap (Fig. 3).
A rupture (white narrow arrows) of the fibrocartilaginous bed of the tendon sheath (Fig. 2-A) and a communication (white arrow) with the ankle joint space were detected by probing (Fig. 2-B).
A hole (white arrow) in the fibrocartilaginous bed was confirmed (Fig. 3-A) and was covered (white narrow arrows) with a periosteal flap (Fig. 3-B).
The ankle was immobilized with a below-knee cast for 3 weeks, and weight-bearing was allowed 10 days postoperatively. The patient was allowed to jog at 10 weeks and returned to rugby practice, except for contact exercises, 16 weeks after the operation. The patient returned to full-contact rugby practice and rugby matches 5 months postoperatively. The patient complained of no symptoms related to the tibialis posterior tendon or the ankle 3 years after the operation.
Case 2
A 16-year-old female gymnast injured her left ankle during forced dorsiflexion at the landing of the vault. The patient was conservatively treated for a mild sprain by a local physician. Six weeks after the injury, she returned to gymnastic activities and was reinjured in an annual national athletic meet. She was treated with below-the-knee cast immobilization for a week, followed by an ankle brace, and was referred to our hospital for prolonged pain for 6 months after the first injury.
No fractures or diastasis of the syndesmosis was detected on routine and weight-bearing radiographs. The hydrocele of the PTT sheath and partial tear of the posterior deltoid ligament were detected on MRI. The patient underwent arthroscopic and tendoscopic examinations, and rupture of the fibrocartilaginous bed of the PTT sheath and communication with the ankle cavity were detected (Fig. 4-A). The ruptured fibrocartilaginous bed was repaired by an open procedure using a periosteal flap (Figs. 4-B and 4-C).
A rupture (white arrows) of the fibrocartilaginous bed of the tendon sheath was detected by tendoscopy of the posterior tibial tendon (PTT; Fig. 4-A). A hole (black arrows) in the fibrocartilaginous bed was confirmed (Fig. 4-B) and was covered (white narrow arrows) with a periosteal flap (Fig. 4-C).
The ankle was immobilized with a below-the-knee cast for 3 weeks, and weight-bearing was allowed for 10 days postoperatively. The patient was allowed to jog at 10 weeks and returned to gymnastics practice 4 months after the operation. The patient complained of no symptoms 2 years postoperatively.
Case 3
A 19-year-old female college gymnast injured her left ankle and reported feeling a “pop” with pain on the posteromedial side of her ankle during a gymnastic floor exercise. Three days after the injury, the patient was admitted to our hospital. The first examination revealed swelling and tenderness in the medial part of the ankle and PTT. There were no findings suggesting fractures or diastasis of the syndesmosis on routine or weight-bearing radiographs. A hydrocele in the PTT sheath and rupture of the posterior deltoid ligament were detected on MRI (Fig. 5).
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Fig. 5: Hydrocele of the posterior tibial tendon (PTT) sheath (white arrow) and rupture (white arrow) of the posterior deltoid ligament were visible on the coronal plane of T2-weighted MRI.
The patient was treated conservatively with below-the-knee cast immobilization and nonsteroidal anti-inflammatory drug administration. However, the pain worsened and the patient underwent arthroscopic and tendoscopic examinations. Rupture of the fibrocartilaginous bed of the PTT sheath and communication with the ankle joint space were detected. The fibrocartilaginous bed was repaired by an open procedure.
The ankle was immobilized with a below-knee cast for 3 weeks, and partial weight-bearing was allowed for 10 days postoperatively. The patient was allowed to jog at 10 weeks and returned to gymnastics practice 3 months postoperatively. She complained of no pain 2 years after the injury.
Discussion
The deltoid ligament of the ankle is a thick and broad ligament that usually consists of 6 components3–6. The superficial layer comprises 4 components: tibionavicular ligament, tibiospring ligament, tibiocalcaneal ligament, and superficial posterior tibiotalar ligament (sPTTL), which comprises 2 components: anterior tibiotalar ligament and deep posterior tibiotalar ligament (dPTTL). The dPTTL is observed consistently, and sPTTL is observed in 93.3% of the specimens in cadaveric studies.3,6
The posterior part of the deltoid ligament is integrated into the tendon sheath of the PTT. Sarrafian named the area the “fibrocartilaginous bed” of the PTT sheath1. Histologically, this complex of the ligament and sheath contains cartilage2. In our study, all 3 patients injured their ankles by forced dorsiflexion with a toe-out position while landing in gymnastics or rugby practice. Because there was no video footage of the injury, the limb positions at the time of injury were based on patient recall. This position of the limb at the injury site is consistent with the injury mechanism of the sPTTL or dPTTL, although an injury to the fibrocartilaginous bed may have been more complex.
Complete rupture of the deltoid ligament is often accompanied by malleolar fractures and/or syndesmosis injury and is treated operatively, followed by below-knee cast immobilization7,8. However, incomplete rupture of the ligament without any fractures or syndesmotic injury can be treated conservatively9,10. Two of our 3 patients complained of cyclic and prolonged symptoms of swelling and pain along the PTT after returning to training. Early exercise may have prevented healing of the ligament and fibrocartilaginous complex by pumping of the joint fluid during ankle motion.
The communication of the 2 cavities between the ankle and the peroneal tendon sheath is common after an inversion sprain involving the calcaneofibular ligament11, although the communication itself does not seem to bother athletes. In our patients, the cavities of the ankle joint and PTT sheath communicated through a pinhole rupture of the deltoid ligament with the fibrocartilaginous complex. We suspected that the check valve phenomenon caused by the pinhole formed in the thick ligament and fibrocartilaginous complex increased the hydraulic pressure of the tendon sheath. We speculate that this pressure change made the symptoms more pronounced, despite the occurrence of only partial ligament damage.
Tendoscopy of the PTT was first described by Wertheimer12 and a detailed technique was introduced by van Dijk13. Indications for tendoscopy of the PTT include tenosynovitis, tendinosis, degenerative tears, tendon adhesion, and dislocation.14–17 In these patients, hydrocele of the PTT sheath was seen on MRI and tenosynovitis was suspected18, although tenosynovitis was not particular, and rupture of the cartilaginous bed was detected. Leakage of joint fluid into the tendon sheath after injury to the joint capsule or ligament can be confirmed by arthrography.11 However, in our opinion, it is difficult to pinpoint the site of the fistula without endoscopy.
The holes were closed using simple suture in 1 patient in the acute phase and using a periosteum flap in 2 patients in the chronic phase by open surgery. The blood patch technique for cerebrospinal fluid hypovolemia is a possible treatment option.19 However, unlike spinal fluid leakage into the epidural tissue, the communication hole between different fluid-filled cavities is difficult to close using blood patches. Patients in this case report took 3 to 5 months to return to their original activities. Whether fibrocartilage complexes require more time for recovery than ligaments is unknown because of the paucity of cases.
In these patients, symptoms developed after forced dorsiflexion of the ankle in a toe-out position during landing motion. Such injuries can occur in any sport, although the risk of deltoid ligament injury is reportedly higher in gymnasts and rugby players than in other sports.20 It is important to consider injury of the fibrocartilaginous complex when a patient complains of persistent pain and swelling along the PTT.
Conclusion
Three athletes with injuries in the fibrocartilaginous bed of the PTT sheath were treated operatively. Simultaneous arthroscopy of the ankle and tendoscopy of the PTT were helpful in diagnosing the communication between the 2 cavities. After surgically closing the pinhole communication, all patients returned to their original sports activities without any symptoms.
Note: The authors thank Editage (www.editage.com) for English language editing.
References
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