UNASSIGNED: Os trigonum and Stieda process are common etiologies for posterior ankle impingement syndrome (PAIS), and diagnosis is typically made by radiographs, computed tomographic, or magnetic resonance imaging. However, these static tests may not detect associated soft tissue and bony pathologies. Posterior ankle and hindfoot arthroscopy (PAHA) is dynamic, providing at least ×8 magnification with full anatomical visualization. The primary aim of this study was to report the prevalence of associated conditions seen with trigonal impingement treated with PAHA.
UNASSIGNED: In this retrospective comparative study, patients who underwent PAHA for PAIS due to trigonal impingement, from January 2011 to September 2016, were reviewed. Concomitant open posterior procedures and other indications for PAHA were excluded. Demographic data were collected with pre- and postoperative diagnosis, arthroscopic findings, type of impingement, location, associated procedures, and anatomical etiologies. Trigonal impingements were divided in os trigonal or Stieda and subgrouped as isolated, with flexor hallucis longus (FHL) disorders, with FHL plus other impingement, and with other impingement lesions.
UNASSIGNED: A total of 111 ankles were studied-74 os trigonum and 37 Stieda. Isolated trigonal disorders accounted for 15.3% of PAIS (n = 17). Cases having associated conditions had a mode of 3 additional pathologies. FHL disorders were found in 69.4%, subtalar impingement in 32.4%, posteromedial ankle synovitis in 25.2%, posterolateral ankle synovitis in 22.5%, and posterior inferior tibiofibular ligament impingement in 19.8% of cases. Associated pathologies were observed in 58.6% of cases when FHL was not considered. Significant differences were noted comparing os and Stieda (isolated: 20.3% to 5.4%, P = .040; FHL plus others: 35.1% to 59.5%, P = .015).
UNASSIGNED: Trigonal bone (os trigonum or Stieda) was found to cause impingement in isolation in a small proportion of cases even when the FHL was considered part of the same disease spectrum. This should alert surgeons when considering removing trigonal impingement. Open approaches may limit the visualization and assessment of associated posterior ankle and subtalar pathoanatomy, thus possibly overlooking concomitant causes of PAIS.
UNASSIGNED: Level III, retrospective comparative study.

UNASSIGNED: The os trigonum is a common cause of posterior ankle impingement in children and adults. Its incidence in the medical literature is controversial. The aim of the study is to determine the incidence of os trigonum, medullary imaging features and size in pediatric patients with suspected posterior ankle impingement.
UNASSIGNED: Fifty-five children (4-16-years-old; 16 girls,) who underwent magnetic resonance ımaging (MRI) with a pre-diagnosis of posterior ankle impingement syndrome (PAIS) were included in the study. Their ankle MRI and lateral radiograms were retrospectively reviewed. The relationship between os trigonum type, size, medullary signal characteristics, and PAIS development was investigated. Skeletal maturity was graded based on the ossification pattern of the calcaneal apophysis. The possible relationship between skeletal maturity and PAIS caused by os trigonum was investigated.
UNASSIGNED: Among the 55 participants, there were 14 participants diagnosed with PAIS (9 boys, mean age 15±1.2 years). There was no connection between the os trigonum type, its medullary signal, gender, and PAIS clinical picture (p>0.05). The os trigonum size causing PAIS was 9±3.4 mm on average. There was a statistically significant relationship between PAIS complaints and os trigonum size (p=0.04). There was no significant relationship between calcaneal stage and PAIS clinical picture (p=0.669). When the os trigonum was fused, all participants were at calcaneal stage 3 or higher.
UNASSIGNED: MRI is superior in detecting fusion of the os trigonum with the talus, the medullary signal of ossicle, and PAIS findings. The most important factor in the development of PAIS is the size of the os trigonum.

OBJECTIVE: The purpose of this study was to identify and characterize various causes of delay in the diagnosis of posterior ankle impingement syndrome (PAIS) in pediatric patients.
METHODS: IRB approved prospective study of patients under 18 years who underwent arthroscopic surgery for the diagnosis of posterior ankle impingement after failed conservative treatment at a tertiary children\'s hospital. Radiographic findings were compared with an age-matched control group. Descriptive and inferential statistics were employed.
RESULTS: 47 patients (61 ankles), mean age 13 years, had an average 14 months delay in diagnosis of PAIS from the initial presentation. 33 (70%) patients had seen multiple medical providers and given other diagnoses. 9 (19%) patients participated in ballet or soccer, and 16 (34%) patients had unrelated associated foot and ankle diagnoses. 25 (41%) of 61 ankles did not have pain on forced plantar flexion; all 61(100%) ankles had tenderness to palpation over the posterior ankle joint line. Radiographs were reported to be normal in 37/52 (71%) ankles, while MRI report did not mention the diagnosis in 20/41 (49%) studies. There was a significant difference in the MRI findings in the patient population when compared to the control group. Indication for surgery was failed conservative treatment. All 61 ankles had posterior ankle impingement pathology confirmed visually during arthroscopy. At average 15 months follow-up, there was significant improvement pre- to post-operatively (p<0.001) for both pain VAS (6.9-0.9) and AOFAS ankle-hindfoot scores (65-94).
CONCLUSIONS: Multiple clinical and imaging factors can lead to delayed diagnosis of posterior ankle impingement. An increased awareness about the features of PAIS is needed amongst medical providers involved in treating young patients.

Posterior ankle pain is a common complaint, and the potential causative pathologic processes are diverse. The constellation of these numerous etiologies has been collectively referred to as posterior ankle impingement syndrome. The pain associated with posterior ankle impingement is caused by bony or soft tissue impingement of the posterior ankle while in terminal plantar flexion. This condition is most frequently encountered in athletes who participate in sports that involve forceful, or repetitive, ankle plantar flexion. This article discusses the associated pathology, diagnosis, conservative treatment, and surgical techniques associated with flexor hallucis longus and posterior ankle impingement syndrome.

UNASSIGNED: Management of ankle pain in dancers can be challenging because of the repetitive stress and complex demands placed on this region. Despite the prevalence of ankle injuries in this population, literature on surgical outcomes and return to dance is limited.
UNASSIGNED: To retrospectively evaluate the efficacy and functional outcomes after surgical excision of a symptomatic os trigonum in dancers.
UNASSIGNED: Case series; Level of evidence, 4.
UNASSIGNED: Between June 2006 and June 2016, a total of 44 dancers underwent surgical excision of a symptomatic os trigonum at a single institution and by a single surgeon. All patients presented with symptoms of posterior ankle impingement syndrome and subsequently failed nonsurgical treatment. Clinical analysis was conducted using various pre- and postoperative patient-reported outcome questionnaires, including the Veterans RAND 12-Item Health Survey (VR-12), Foot Function Index-Revised (FFI-R), and visual analog scale (VAS) for pain, as well as subjective patient satisfaction.
UNASSIGNED: A total of 44 patients (54 ankles; mean age, 18.2 years) were retrospectively evaluated at a mean follow-up of 33.4 months. The VR-12 Physical Health score improved from a mean score of 37.8 ± 11.9 to 51.2 ± 10.5 (P < .001). The cumulative FFI-R score improved from 46.45 ± 13.8 to 31.2 ± 9.7 (P = .044), with the subcategory of \"activity limitation\" representing the highest-scoring FFI-R subcategory at 65.28 ± 13.4 preoperatively and improving to 34.47 ± 12.4 at follow-up (P < .001). The mean VAS score for subjective pain improved significantly from 5.39 ± 2.84 to 1.73 ± 2.10 (P < .00044).
UNASSIGNED: Overall, the findings of the present study demonstrate that dancers of varying style and level improved significantly according to various clinical measures. Patients included in this study reported that they returned to their previous level of dance upon completion of physical therapy and maintained thriving postoperative careers, which for several meant dancing at the professional level.

Posterior ankle impingement is a cause of posterior ankle pain common in those who perform frequent plantarflexion activities. Three young patients presented with posterior ankle pain which was initially attributed to peroneal tendon subluxation. However, detailed physical exam and imaging confirmed the diagnosis of posterior ankle impingement as the actual cause of pain. The peroneal tendon subluxation was not causal but an unrelated co-incidental finding. After failed prolonged conservative management (rest, immobilization and physical therapy), the patients underwent posterior ankle arthroscopic debridement for the impingement resulting in return to prior sporting activity without limitation and no recurrence of pain at 19 months follow-up. Posterior ankle impingement diagnosis could be masked by co-incidental asymptomatic peroneal tendon subluxation in pediatric patients.

Posterior ankle impingement syndrome (PAIS) results from the pinching of anatomical structures in the posterior part of the ankle.
To identify the possible role of imaging in the delayed diagnosis of PAIS and identify key findings on imaging to suggest PAIS in pediatric and adolescent patients.
Data were collected prospectively in patients younger than 18 years of age who underwent arthroscopy after being diagnosed with PAIS. Imaging was reviewed retrospectively by two radiologists, compared with findings in literature and an age-matched control group, and correlated with arthroscopic findings. Pre- and postsurgical Visual Analogue Scale (VAS) pain and American Orthopedic Foot Ankle Society (AOFAS) ankle-hindfoot scores were noted.
Thirty-eight patients (20 females, 18 males), 51 ankles, with an average age of 12.9 years had an average 18-month delay in diagnosis. Twenty-seven of the 38 (73%) patients had previously seen multiple medical providers and were given multiple misdiagnoses. Radiographs were reported normal in 34/47 (72%) ankles. Thirty patients had magnetic resonance imaging (MRI) and findings included the presence of an os trigonum/Stieda process (94%) with associated osseous edema (69%), flexor hallucis longus (FHL) tenosynovitis (16%), and edema in Kager\'s fat pad (63%). Although individual findings were noted, the impression in the MRI reports in 16/32 (50%) did not mention PAIS as the likely diagnosis. There was a significant difference in the MRI findings of ankle impingement in the patient population when compared to the control group. Surgery was indicated after conservative treatment failed. All 51 ankles had a PAIS diagnosis confirmed during arthroscopy. At an average follow-up of 10.2 months, there was improvement of VAS pain (7.0 to 1.1) and AOFAS ankle-hindfoot scores (65.1 to 93.5).
PAIS as a diagnosis is commonly delayed clinically in young patients with radiologic misinterpretation being a contributing factor. Increased awareness about this condition is needed among radiologists and physicians treating young athletes.

Talus partitus is a rare skeletal developmental abnormality characterized by a split of the posterior talar bone in the coronal plane. Patients with talus partitus typically present with posterior ankle pain and instability, often displaying varying degrees of chondrosis and secondary degenerative change on imaging. To date, only few case reports describing the imaging appearance of talus partitus have been published. The majority of these publications are limited to radiographic and computed tomography (CT) imaging findings, despite the ubiquity of magnetic resonance imaging (MRI). To the authors\' knowledge, there is little description of typical MRI findings of the symptomatic talus partitus in the radiologic literature. We present a series of five cases of talus partitus identified on MRI and examine pitfalls in diagnosis, differential considerations, pathophysiology, and treatment options.

BACKGROUND: Os trigonum syndrome is a relatively uncommon condition, resulting from compression of a congenital bony anomaly (os trigonum) and adjacent soft tissues during repetitive hyper-plantarflexion. This condition is currently well-described in ballet, soccer, and running athletes, but few cases exist describing os trigonum syndrome in overhead athletes.
METHODS: A 22-year-old national level male javelin athlete presented with a recalcitrant history of posterior ankle pain following a hyper-plantarflexion mechanism. Imaging demonstrated a symptomatic os trigonum and inflammation of surrounding soft tissues. Re-aggravation following a conservative trial of care led to orthopaedic referral. Surgical excision of the os trigonum was performed with an open posterolateral approach. The athlete returned to competition three months later with no recurrence of symptoms.
CONCLUSIONS: This case discusses the clinical presentation, imaging, and management of a symptomatic os trigonum and related pathologies in a javelin thrower.
BACKGROUND: Le syndrome de l’os trigone est une pathologie relativement peu fréquente causée par la compression d’une anomalie osseuse congénitale (os trigone) et des tissus mous adjacents durant les mouvements répétitifs en hyperflexion plantaire. Cette pathologie touche souvent les danseuses de ballet, les joueurs de soccer et les coureurs. Peu de cas sont enregistrés chez les athlètes pratiquant des sports comportant des mouvements au-dessus de la tête.
UNASSIGNED: Un lanceur de javelot de 22 ans se plaignait d’une douleur postérieure de la cheville déclenchée par des mouvements répétitifs en hyperflexion plantaire. Les examens par imagerie montraient un os trigone symptomatique et une inflammation des tissus périphériques. Une aggravation après une tentative de traitement conservateur a mené à une demande d’une consultation en orthopédie. L’excision chirurgicale de l’os trigone a été réalisée à ciel ouvert par voie d’abord ouverte postérolatérale. L’athlète e repris la compétition au bout de trois mois; ses symptômes ne sont pas réapparus.
UNASSIGNED: Cette étude de cas présente le tableau clinique, les examens par imagerie et la prise en charge d’un os trigone symptomatique et des pathologies apparentées observés chez un lanceur de javelot.

The os trigonum is known as one of the main causes of posterior ankle impingement. In the literature, a wide variation of occurrence has been reported.
All foot and/or ankle computed tomography (CT) scans made between January 2012 and December 2013 were reviewed. CT images were assessed, blinded for patient characteristics, for the presence of an os trigonum, size of the os trigonum, and type of os trigonum. In addition, the shape of the lateral tubercle of the posterior talar process was assessed.
A total of 628 patients (1256 ankles) were included. In 32.5% of the patients of the cohort, an os trigonum was present. In 14.3% of these patients, it was present bilaterally. In a subgroup of patients without posterior ankle impingement the prevalence was 30.3%. Of the nonaffected ankles, an os trigonum was present in 23.7%. Patients with posterior ankle impingement were more likely to have an os trigonum (adjusted odds ratio [OR], 1.86). Afro-Caribbean/Surinamese/Central African origin was associated with a lower rate of occurrence of os trigonum (adjusted OR 0.43). In the ankles without an os trigonum, an enlarged lateral tubercle of the posterior talar process was found in 34.9% and 36.5% of the ankles.
This study showed that os trigonum is a common accessory bone. With a prevalence of 30.3% in a population of patients with CT imaging of both ankles and 23.7% of the nonaffected ankles, the os trigonum is more common than previously reported. Patients with posterior ankle impingement complaints had a higher prevalence of an os trigonum. In one-third of the patients without an os trigonum, there was an enlarged lateral tubercle of the posterior talar process.
Level III, retrospective comparative study.