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.     

疼痛性跟距联合的治疗

目的 :探讨疼痛性跟距联合手术治疗适应证及术式。方法 :根据术前跟距轴位CT扫描所测量的跟距联合与跟距后关节二者横向切面之比率及跟骨外翻角度来决定采取跟距骨桥局部切除或三关节融合术。共治疗 12例 16足 ,其中男 8例 ,女 4例。平均随访时间 18个月。结果 :术后根据患者症状消失程度分为优良、可、差。单纯行跟距联合切除者 9例 12足 ,其中优 6例 ,可 3例 ;三关节融合者 3例 4足 ,均为优良。结论 :经保守治疗无效者可行手术治疗 ,跟距联合与跟距后关节二者横向切面之比率 <5 0 % ,跟骨外翻角 <2 1°时可行跟距骨桥局部切除术 ,反之则应行三关节融合术。     

Geometrical characteristics of the symptomatic and non-symptomatic ossa trigona

BackgroundPosterior ankle impingement is strongly associated with the presence of an os trigonum, however, most patients with an os trigonum will never develop symptoms. It is hypothesized that the os trigonum is larger in the symptomatic ankle than in the non-symptomatic ankle, the distance between os trigonum and tibia is smaller and there are more degenerative changes in ankles with symptoms of posterior impingement. In this study the geometrical characteristics of the ipsilateral and contralateral os trigonum are compared in patients with a bilateral os trigonum and unilateral posterior impingement symptoms.MethodsPatients with a bilateral os trigonum and unilateral posterior impingement complaints were included. Comparison between the symptomatic and asymptomatic ankles was done within each patient. From the CT-scan of each ankle, the tibia, fibula, calcaneus, talus and os trigonum were segmented and a geometric model was created. Based on these bone models, the volume of the os trigonum and talus, the size of the os trigonum, the distance between os trigonum and surrounding bones (talus, calcaneus, fibula and tibia) were calculated. In addition, the CT images were assessed for the type of os trigonum, the presence of cysts, irregular synchondrosis, calcifications and whether the os trigonum consisted of more than one fragment.ResultsA total of 22 patients were included in this study. In seventeen of the 22 patients, the symptomatic os trigonum was larger in comparison with the non-symptomatic side in terms of length (median Δ 2.4 mm, 8.9 versus 10.6 mm) and relative volume (median Δ 0.09%, 0.30 versus 0.45% of talar volume). Distances between the ossa trigona and surrounding bones were not statistically significantly different between both sides. Calcifications were more frequently found around the os trigonum in the symptomatic side (10 versus 3/22).ConclusionsThe findings in this study support the hypothesis that symptomatic ossa trigona are larger in comparison with asymptomatic ossa trigona. Calcifications around the os trigonum were found more frequently in symptomatic than in non-symptomatic ossa trigona.Level of EvidenceIII.     

Dorsomediale talokalkaneare Koalition

Talocalcaneal coalitions are rare but a posterior facet talocalcaneal coalition is even rarer. There are three different types: fibrous, cartilaginous and osseous coalitions. Besides conventional x-rays computed tomography is essential for assessment of the subtarsal joint. In the absence of concomitant coalitions and foot deformity resection of the coalition is advocated due to good clinical results when there is an adequate size of the talocalcaneal joint (>50%) and without osteoarthrosis. A case of a rare posterior facet talocalcaneal coalition is reported.     

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.     

Posterior Ankle Impingement: Clarification and Confirmation of the Pathoanatomy

The diagnosis of posterior hindfoot pain may prove to be elusive as there are many potential causes of hindfoot pain, including both soft tissue and osseous abnormalities. This is a case presentation of os trigonum syndrome, with the diagnosis suggested by magnetic resonance imaging (MRI), confirmed by ultrasound, and treated with os trigonum resection. Specific findings of os trigonum syndrome can be seen on MRI, including bone marrow edema pattern and high signal intensity in the synchondrosis as well as in the surrounding soft tissues. Diagnostic injections performed with imaging guidance can help confirm the diagnosis in equivocal cases. Diagnostic and interventional imaging procedures can help confirm the diagnosis of os trigonum syndrome in a patient presenting with hindfoot pain.     

Outcome of resection of a symptomatic os trigonum

BACKGROUND: While an os trigonum at the posterolateral aspect of the talus is usually asymptomatic, this inconsistently present accessory bone has been associated with persistent posterior ankle pain, which has been described as the os trigonum syndrome. We present the clinical results of excision of the os trigonum through a posterolateral approach and report several factors affecting the clinical outcome. METHODS: During a five-year period from 1994 through 1999, forty-one patients had a failure of nonoperative treatment of os trigonum syndrome and underwent excision of a symptomatic os trigonum. In all cases, the os trigonum syndrome was diagnosed on the basis of the history, physical examination, and radiographs. Postoperatively, the patients were evaluated according to the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale. A questionnaire was used to evaluate the effect of several factors on the clinical outcome. RESULTS: The average duration of follow-up was forty-four months. The postoperative AOFAS score averaged 87.6 points. The thirty-three patients who had had symptoms for two years or less prior to the surgery had an average postoperative score of 90 points compared with 78 points for the eight patients who had had preoperative symptoms for more than two years (p = 0.011). Eight patients had sural nerve sensory loss, which was temporary in four and permanent in four. A superficial wound infection developed in one patient, and reflex sympathetic dystrophy developed in another. CONCLUSIONS: An os trigonum that is persistently symptomatic after a minimum three-month trial of nonoperative treatment can be excised through a posterolateral approach with highly satisfactory results. The main complication of this procedure is sural nerve injury.     

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.     

Talo-calcaneal coalition treated with resection

Three cases of symptomatic talocalcaneal coalition (medial or posterior) have been treated successfully with resection of the connecting bar and fat interposition without fusion. At follow-up (ranging from 1 1/2 to 14 years), the patients had no pain, good function, good range of joint motion, and no regeneration of the bar. Computed tomography scanning was the method of choice for roentgenological diagnosis of talocalcaneal coalition.     

A Novel Technique of Arthroscopic Excision of a Symptomatic Os Trigonum

We describe a new arthroscopic excision technique for a symptomatic os trigonum. With the patient lying in a prone position, a posterolateral portal just lateral to the Achilles tendon, at the 5-mm level proximal to the tip of the fibula, is used for the arthroscope and an accessory posterolateral portal just posterior to the peroneal tendon at the same level is used for instruments. The synovial tissues are then debrided with a power shaver through the accessory posterolateral portal for better visualization. An elevator is used to release the fibrous tissue between the os trigonum and the talus. The os trigonum is completely excised with a grasper to visualize the flexor hallucis longus tendon. Radiographic control is helpful to check the position of the arthroscope if it happens to be inserted into the ankle joint as a result of the reduced subtalar joint space. Postoperatively, no immobilization is necessary, and full weight-bearing is allowed as tolerated. Three of us have performed 11 procedures with excellent results and no cases of complications. This arthroscopic excision technique for the symptomatic os trigonum is a safe and effective procedure.     

A 2-portal endoscopic approach for diagnosis and treatment of posterior ankle pathology

Summary: We describe a 2-portal endoscopic approach of the hindfoot with the patient in the prone position. By means of this approach, it is possible to visualize and treat a variety of posterior ankle problems. Not only can pathology of the posterior ankle joint and subtalar joint be visualized and treated, but also periarticular pathology, such as calcifications or scar tissue, can be diagnosed and treated. We describe a professional ballet dancer with chronic flexor hallucis longus tendinitis and a posterior ankle impingement syndrome caused by an os trigonum of both ankles. The patient was successfully treated by removing the os trigonum and releasing the flexor hallucis longus tendon. She resumed her professional activities within 2 months after endoscopic treatment.     

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.     

Endoscopic Excision of Symptomatic Os Trigonum in Professional Dancers

The present study reports the clinical results of excision of a symptomatic os trigonum using an endoscopic procedure in professional ballet dancers. The hypothesis was that posterior endoscopic excision of the os trigonum would be safe and effective in treating posterior ankle impingement syndrome related to the os trigonum. Twelve professional dancers underwent excision of a symptomatic os trigonum for PAIS using a posterior endoscopic technique after failure of conservative treatment. The patients were evaluated pre- and postoperatively according to the American Orthopaedic Foot and Ankle Society hindfoot scale score, the Tegner activity scale score, and the visual analog scale score. The surgical time, timing of a return to sports, patient satisfaction, and any complications related to the procedure were recorded. The average postoperative follow-up duration was 38.9 ± 20.6 (range 12 to 72) months. The mean Tegner activity scale score increased from 4.3 ± 0.8 (range 3 to 5) preoperatively to 9 ± 0.2 postoperatively (p < .05). The mean American Orthopaedic Foot and Ankle Society scale score increased from 67.8 ± 6.0 (range 58 to 76) preoperatively to 96 ± 5.1 (range 87 to 100) postoperatively, with 7 of 12 patients (58.3%) reporting the maximum score of 100 points (p < .05). The return to sports was 8.7 ± 0.7 (range 8 to 10) weeks. No major complications were recorded. The results of the present study demonstrate that the endoscopic excision of symptomatic os trigonum using a 2-portal technique after failure of conservative treatment is characterized by excellent results with low morbidity.     

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.     

Posterior talocalcaneal coalition

Tarsal coalition is a rare congenital deformity. The most common coalitions involve the calcaneonavicular joint and the medial facet of the talocalcaneal joint. The posterior facet is rarely involved. We report a case of a patient with a posterior talocalcaneal bar who presented with painful limitation of subtalar motion without the classical appearance of spastic flat foot. Resection of the bar with interposition of fat graft resulted in an almost full range of pain-free subtalar motion.     

手术治疗跟距骨桥疗效观察

目的探讨跟距骨桥的手术治疗方法及疗效。方法 2008年7月-2010年10月,手术治疗跟距骨桥患者10例。男4例,女6例;年龄16～70岁,平均53.5岁。先天性骨桥2例,继发性骨桥8例。跟距中间关节面骨桥3例,后关节面骨桥7例。术前患者疼痛视觉模拟评分(VAS)为(9.0±0.4)分;根据美国矫形足踝协会(AOFAS)后足评分标准为(42.4±1.4)分。合并距下关节退变2例。8例单纯跟距骨桥患者行骨桥切除并脂肪组织植入,2例合并距下关节退变患者行骨桥切除联合距下关节融合术。结果术后切口均Ⅰ期愈合。8例获随访,随访时间12～36个月,平均18个月。末次随访时VAS评分为(2.0±0.7)分,与术前比较差异有统计学意义(t=6.425,P=0.000)。AOFAS后足评分为(86.9±2.3)分,与术前比较差异有统计学意义(t=7.634,P=0.000)。单纯骨桥切除者末次随访时X线片检查示无骨桥复发及关节退变发生,关节融合者X线片示达骨性融合。结论跟距骨桥根据不同发生部位和合并症,分别采用单纯骨桥切除或联合距下关节融合术可取得较好疗效。     

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.     

关节镜下改良后踝入路切除治疗成人疼痛性跟距骨桥

目的探讨采用关节镜下改良后踝入路切除治疗成人疼痛性跟距骨桥的疗效。方法 2015年1月-2017年12月,采用后踝高位外侧观察入路结合低位内侧操作入路切除治疗9例成人疼痛性跟距骨桥。男6例,女3例;年龄19~30岁,平均24岁。2例无明确局部外伤,7例有足踝部扭伤病史。病程6~30个月,中位病程12个月。跟距骨桥Rozansky分型:Ⅰ型5例(5足),Ⅱ型2例(2足),Ⅲ型2例(2足)。患者既往无肢体功能障碍后遗症、无肢体关节手术史。术后随访复查踝关节正侧位X线片、踝关节CT。比较手术前后疼痛视觉模拟评分(VAS)及美国矫形足踝协会(AOFAS)踝-后足评分。结果患者手术时间60~90 min,平均76 min。术后患者均获随访,随访时间12~24个月,平均18个月。术后切口均Ⅰ期愈合,无感染、皮肤坏死、下肢深静脉血栓形成、血管神经及肌腱损伤、骨桥复发等并发症发生。术后踝关节功能恢复良好,疼痛明显缓解;患者于术后3~5个月,平均3.9个月重返工作岗位。末次随访时VAS评分为(0.7±0.5)分,与术前(4.2±0.5)分比较差异有统计学意义(t=20.239,P=0.000);AOFAS踝-后足评分为(94±4)分,与术前(62±2)分比较差异有统计学意义(t=–27.424,P=0.000),末次随访时获优7例,良2例。结论后踝高位外侧观察入路结合低位内侧操作入路显露跟距骨桥更直观,操作空间更大,操作过程更灵活,术中根据特定解剖标志程序化切除跟距骨桥,操作具有可行性。     

Evaluation of the Prevalence of Os Trigonum and Talus Osteochondral Lesions in Ankle Magnetic Resonance Imaging of Patients With Ankle Impingement Syndrome

The prevalence of os trigonum and osteochondral lesions of talus (OCLT) have been presented in different prevalences among different groups in the literature for the patients with ankle impingement syndrome. Our main objective in the study was to determine the possible relationship between the impingement syndrome and the prevalence of os trigonum and OCLT in specific groups. The presence of anterior ankle impingement syndrome (AAIS), posterior ankle impingement syndrome (PAIS), os trigonum, OCLT, and the location of OCLT were evaluated in a blinded manner on magnetic resonance imaging from patients clinically considered to be diagnosed with ankle impingement syndrome from January 2014 to July 2017. The patients were separated into specific groups according to the confirmation of their clinical diagnosis of ankle impingement syndrome on magnetic resonance imaging . A total of 333 patients were included. The prevalence of os trigonum was found to be 1.3% in patients with PAIS(-) AAIS(+), 7.7% in patients with PAIS(-) AAIS(-), 63.3% in patients with PAIS(+) AAIS(-), and 81.1% in patients with PAIS(+) AAIS(+) (p < .001). The prevalence of OCLT was found to be 41.3% in patients with PAIS(-) AAIS(+), 23.1% in patients with PAIS(-) AAIS(-), 18.3% in patients with PAIS(+) AAIS(-), and 27% in patients with PAIS(+) AAIS(+) (p= .005). Our study showed that, for patients with isolated PAIS and AAIS combined with PAIS, the prevalence of os trigonum was 63.3% and 81.1%, respectively, which is more common than previously reported. For patients with isolated AAIS and PAIS, the prevalence of OCLT was 41.3% and 18.3%, respectively. Of the OCLTs combined with ankle impingement syndromes, 87.1% were medially located.