Excision of os trigonum

Os trigonum impingement is a cause of posterior ankle pain in ballet dancers and other athletes who forcibly point their feet. It must be distinguished from other causes of posterolateral ankle pain. A course of nonsurgical therapy is recommended as the initial treatment. In those cases where conservative treatment fails, good results have been obtained by surgical excision of the accessory ossicle. Both lateral and medial surgical approaches are described.     

Anatomy of the os trigonum

Three anatomic specimens of os trigonum from skeletally immature patients demonstrated anatomic continuity of the cartilage containing the ossicle with the body of the talus, with a synchondrosis being present between the two ossifying regions. The os trigonum may be considered a developmental analogue of a secondary ossification center similar to the posterior calcaneal apophysis (although there are obvious histologic differences). The chondro-osseous border of the synchondrosis may be injured either as a chronic stress fracture or, less frequently, as an acute fracture, comparable to the injury patterns involving the accessory navicular.     

Symptomatic os trigonum in children

BackgroundSymptomatic os trigonum is a rare condition well described in adults responsible for chronic ankle pain. To date there is no published case of successfully managed symptomatic os trigonum in children.MethodsWe retrospectively reviewed 4 paediatric patients (11–17) successfully operated on for a symptomatic os trigonum through a postero medial approach. One case was bilateral.ResultsPain relief was postoperatively obtained in all cases. All of the patients were able to return to physical activities after 3 months. The mean follow up was 12 months.ConclusionSymptomatic os trigonum may be responsible for chronic ankle pain in children and adolescents as well as in adults. The surgical treatment is effective in children.     

Fracture of the os trigonum: a case report

The os trigonum is an inconsistently present accessory bone of the foot situated at the posterolateral aspect of the talus. It may be radiographically confused with fractures of the posterior process of the talus. Fracture of the os trigonum per se is extremely rare. Hyperplantarflexion of the ankle is the mechanism of injury in which the os trigonum is compressed between the posterior malleolus of the tibia and the tuber calcaneus. Computed tomography is the choice of imaging modality in cases where fractures of posterior talus structures, including the os trigonum, are suspected. A high index of suspicion is necessary to diagnose a fracture of the os trigonum after a severe plantarflexion injury to the ankle. Conservative treatment is usually successful. We report a case of a fracture of the os trigonum, its clinical features, treatment and significance.     

Intraosseous tophus deposits in the os trigonum

High levels of uric acid cause accumulation of monosodium urate crystals. This formation of masses is called tophus. Intraosseous tophus deposits are rare, even for patients with gout. We report an unusual case of intraosseous tophus deposits in the os trigonum. The patient presented with ankle pain with no previous history of gout. On examination, tenderness on the posterior aspect of his ankle and limitation of plantarflexion was noted. Laboratory values were normal, except for an elevated serum uric acid value. Radiographs of the right ankle showed the presence of a large os trigonum with osteosclerotic changes, whereas magnetic resonance imaging showed intraosseous tophus deposits in the os trigonum. Conservative therapy failed, and the patient was admitted for an endoscopic resection of the os trigonum.Intraosseous chalky crystals were detected during endoscopic resection of the os trigonum. The histological diagnosis was tophaceous gout. The underlying pathological mechanism of intraosseous tophi is uncertain. Penetration of urate crystals from the joint due to hyperuricemia may be the mechanism of deposition in this patient.When a patient with hyperuricemia presents with posterior ankle impingement symptoms, intraosseous tophus deposits should be included in the differential diagnosis. Posterior endoscopic excision may be an option for treating intraosseous lesions of the os trigonum because of good visualization, satisfactory excision, and rapid recovery time.     

Osteo-arthritis of the os trigonum–calcaneal joint

Os trigonum is an incidental radiographic finding at the posterior aspect of the talus in around 10% of the population. A small proportion are symptomatic as part of Posterior Ankle Impingement (os trigonum syndrome), in which several structural and inflammatory changes may be demonstrated on MRI.We report a case of an os trigonum–calcaneal joint associated with dysplastic talus in a patient without primary posterior ankle impingement syndrome. She presented with clinical and radiographical evidence of osteoarthritis within this joint, which responded well to surgical excision via a postero-medial approach.     

Acquired talo-calcaneal coalition due to injury to the os trigonum

The os trigonum has been associated with a variety of conditions, most of which result in painful syndromes at the posterior aspect of the ankle joint. An uncommon complication is formation of a talocalcaneal coalition. We present a previously undescribed case of posterior talocalcaneal coalition that resulted after a plantarflexion injury of the os trigonum.     

Pseudo os trigonum sign: missed posteromedial talar facet fracture

BACKGROUND: Posteromedial talar facet fracture (PMTFF) is a rare injury, sparsely reported in the literature. This article proposes that PMTFF is often left undiagnosed by orthopaedic surgeons and suggests the routine application of advanced radiographic studies (i.e., CT scan) in the recognition of PMTFF. It also evaluates nonoperative management of PMTFF. METHODS: After obtaining Institutional Review Board approval, the medical records over a 5-year period (1997-2001) were retrospectively reviewed from the foot and ankle service of a level 1 trauma center, identifying all cases of PMTFF. Charts were reviewed for relevant data. Results of treatment were assessed during follow-up physical examination. RESULTS: Six cases of PMTFF were identified over a 5-year period. All injuries were associated with medial subtalar joint dislocation. Four of six (66%) patients were not initially diagnosed with PMTFF, but instead misdiagnosed as an os trigonum. The remaining two patients had an established diagnosis of PMTFF at the time of initial treatment. All had short leg cast immobilization for medial subtalar dislocation. CT evaluation yielded additional diagnoses in all six patients. All six patients showed a PMTFF. Five patients (83%) revealed persistent subtalar joint subluxation. Five of six (83%) patients required at least one additional procedure as a result of an undiagnosed or nonoperatively treated PMTFF. Four patients underwent subtalar joint fusion, and one patient underwent tibiotalar calcaneal fusion secondary to concomitant ankle/subtalar arthritis. The patient who did not undergo recommended fusion continued to be symptomatic. CONCLUSIONS: Diagnosis of PMTFF necessitates a heightened clinical suspicion, especially when a medial subtalar joint dislocation is present. Proper imaging studies, such as coronal CT scan, should be performed after any subtalar dislocation. Timely treatment, in the form of open reduction and internal fixation for large fragments involving the articular surface or surgical excision for smaller fragments, is recommended in order to restore proper anatomy and function of the subtalar joint. This study verifies the significant morbidity associated with an undiagnosed or nonoperatively treated PMTFF.     

The os trigonum syndrome: use of bone scan in the diagnosis

The os trigonum is an accessory bone of the foot found in 7% of the normal adult population. It is located at the posterolateral projection of the talus, and can occasionally give rise to symptoms of acute and chronic unexplained ankle pain. We report three patients, one with acute fracture and two with chronic ankle symptoms. Technetium 99 methylene diphosphonate showed intense focal uptake at the posterior talus pointing to the os trigonum as the site of symptoms. It was excised in two patients with complete relief. The third went on to develop an asymptomatic nonunion. We recommend bone scanning as a procedure that is helpful in delineating obscure pain in the ankle that may be due to chronic irritative nonunion of the os trigonum.     

Arthroscopic excision of the os trigonum: using the posteromedial portal safely

The os trigonum is an accessory ossicle that, though usually asymptomatic, can become a chronic source of pain, particularly in dancers and athletes. Surgical intervention is sometimes necessary, with arthroscopy having the theoretical advantages of less pain, inflammation, and scarring. Presented here is an example of chronic posterior ankle pain in an athlete successfully treated with arthroscopic os trigonum resection using posteromedial and posterolateral portals. We review the technical features and surgical technique of safe placement of the posteromedial portal and associated advantages.     

Modified arthroscopic excision of the symptomatic os trigonum and release of the flexor hallucis longus tendon: operative technique and case study.

This article presents an operative technique for modified arthroscopic excision of the symptomatic os trigonum and release of the flexor hallucis longus tendon sheath. The procedure uses two stacked posterolateral subtalar joint portals, rather than the customary anterolateral and posterolateral portal combination. By visualizing the os trigonum with an arthroscope positioned in a distal portal and introducing instrumentation through a proximal portal, the ossicle may be quickly exposed and excised with minimal dissection. A case study with a 22-month follow-up and a discussion of os trigonum syndrome are included to illustrate this procedure as an alternative to open excision or traditional arthroscopic excision.     

The treatment of symptomatic os acromiale

Os acromiale is an uncommon condition of the shoulder. When symptomatic, os acromiale may cause impingement pain, rotator cuff tears, or pain through abnormal motion at the unfused apophysis. Treatment of symptomatic os acromiale is controversial. This article reports on four patients with symptomatic meso-acromions who were treated with open reduction and internal fixation. All four patients recovered full function postoperatively with UCLA shoulder rating scores improving from 19 preoperatively to 35 postoperatively. Open reduction and internal fixation of a symptomatic meso-acromion is a reliable and reproducible technique in which the deltoid attachment and lever arm are minimally affected.     

The coexistence of os trigonum,accessory navicular bone and os peroneum and associated tendon and bone pathologies

PurposeTo determine how often os trigonum is accompanied by accessory navicular and os peroneum. A secondary aim of the study was to investigate the bone and related tendon pathologies that may develop in these three accessory bones.Materials and methodsA total of 110 patients who were evaluated by ankle MRI and were determined with os trigonum between 2009–2015 were included in the study. The frequency was determined of os trigonum together with accessory navicular bone and os peroneum. MR images were also evaluated in respect of bone pathologies and related tendon pathologies of these 3 accessory bones.ResultsOf 110 patients determined with os trigonum on MRI, 21 (19%) were also determined with accessory navicular bone and 5 (4.5%) with os peroneum.When bone pathologies were examined, the most frequently seen pathology was bone marrow edema.The most common pathology in the tendons related to the accessory bones was increased amount of synovial fluid within the tendon sheath. In cases with os trigonum, bone changes were observed more frequently than pathologies of the adjacent tendons, in the accessory navicular bone cases, tendon pathologies were observed more than bone changes and in the cases with os peroneum, bone and tendon pathologies were determined at equal rates.There was no significant difference in terms of FHL tendon pathology between patients with and without edema in os trigonum. However, TP tendon was significantly more pathological in patients with edema in accessory navicular bone.ConclusionMore than one accessory bone was determined in approximately one in four cases.The most common pathologies determined in these accessory bones was bone marrow edema and increased amount of synovial fluid within the tendon sheath.It is necessary to investigate and report all these findings on MRI as they play an important role in the explanation of clinical findings and treatment planning.     

Bone scintigraphic findings of os trigonum: a prospective study of 100 soldiers on active duty

PURPOSE: To determine the clinical significance of an increased uptake of 99mTc methylene-diphosphonate (Tc-MDP) in the os trigonum region seen on bone scintigrams of soldiers on active duty. PATIENTS AND METHODS: Radionuclide whole-body skeletal imaging and physical examination of the foot were carried out in 100 consecutive soldiers on active duty referred for evaluation of suspected stress-injury of the lower limbs, back pain, and different skeletal trauma. Lateral radiographs of the foot were performed in those with increased uptake of Tc-MDP at the site of os trigonum. Radiographic, scintigraphic, and clinical findings were correlated. RESULTS: Among 200 feet, 27 (13.5%) showed an increased uptake of Tc-MDP in the os trigonum region. The right side was affected in six patients, the left side in 11 and five patients had bilaterally increased uptake. On X-rays, 31 of 44 feet showed the os trigonum. Only 10 of these 27 feet (37%) had a symptomatic os trigonum. CONCLUSIONS: Our results suggest that increased uptake of Tc-MDP in the os trigonum region is a frequent finding among active soldiers and is of limited value in detecting symptomatic os trigonum.