UNASSIGNED: Previous research in sport populations has demonstrated that abnormal magnetic resonance imaging (MRI) findings may be present in individuals without symptoms or known pathology. Extending this understanding to ballet, particularly in relation to the foot and ankle, is important to guide medical advice given to dancers.
UNASSIGNED: To assess foot and ankle MRI scans in asymptomatic ballet dancers focusing on bone marrow edema and the posterior ankle and to investigate whether these MRI findings would become symptomatic within 1 year.
UNASSIGNED: Case series; Level of evidence, 4.
UNASSIGNED: In total, 31 healthy dancers (62 feet/ankles; 15 male and 16 female; age, 26.5 ± 4.3 years) who were dancing in full capacity were recruited from an elite professional ballet company. Orthogonal 3-plane short tau inversion recovery imaging of both feet and ankles was obtained using 3T MRI and the images were reviewed using a standardized evaluation form by 2 musculoskeletal radiologists. Injuries in the company were recorded and positive MRI findings were assessed for correlation with any injuries requiring medical attention during the subsequent 12 months.
UNASSIGNED: A total of 51 (82%) of the 62 feet and ankles had ≥1 area of bone marrow edema. The most common locations of bone marrow edema were the talus (n = 41; 66%), followed by first metatarsal (n = 14; 23%). Os trigonum and Stieda process were seen in 5 (8%) and 8 (13%) ankles, respectively. Among them, 2 os trigona showed bone marrow edema. Fluid in the anterior and posterior talocrural joints and the subtalar joint was observed in 48%, 63%, and 63% of these joints, respectively. Fluid around foot and ankle tendons was observed, with the most prevalent being the flexor hallucis longus tendon (n = 13; 21%). Two dancers who had positive findings on their MRI subsequently developed symptoms during the next 12 months.
UNASSIGNED: Positive MRI findings are commonplace in the foot and ankle of asymptomatic professional ballet dancers. The majority do not result in the development of symptoms requiring medical attention within 12 months. Careful interpretation of MRI findings with the dancer\'s clinical picture is required before recommending activity modification or further intervention.

BACKGROUND: Posterior ankle impingement syndrome (PAIS) is sometimes complicated by bilateral cases and lateral ankle ligament injuries. Reports on bilateral surgery for PAIS and simultaneous surgery for lateral ankle ligament injury are scarce in the literature.
METHODS: We present a 2-year follow-up of 76 athletic patients who underwent endoscopic hindfoot surgery for PAIS. Patients were divided into those who underwent unilateral or simultaneous bilateral surgery and PAIS surgery alone or simultaneous bilateral PAIS surgery without arthroscopic ankle lateral ligament repair.
RESULTS: All patients returned to full athletic activities postoperatively. There was no difference in all subscales of the SAFE-Q score between groups except for mean days after surgery for full return to athletic activities.
CONCLUSIONS: Simultaneous bilateral surgery and simultaneous arthroscopic lateral ankle ligament repair had no negative effect on subjective clinical evaluation 2 years after surgery in hindfoot endoscopic surgery for PAIS.
METHODS: III, retrospective case-control study.

UNASSIGNED: Surgical intervention is not typically used to treat symptoms after mild tibiofibular ligament injuries without ankle dislocation or subluxation.
UNASSIGNED: To describe outcomes in patients arthroscopically treated for unique intra-articular lesions after sustaining syndesmosis injury of the ankle.
UNASSIGNED: Case series; Level of evidence, 4.
UNASSIGNED: A total of 11 elite male rugby players with a mean age of 21.0 years (range, 17-28 years) were referred to our hospital for prolonged posterior ankle pain after a high ankle sprain during rugby football. The patients were examined using standing view radiography, computed tomography (CT) and magnetic resonance imaging (MRI) to determine the extent of ligament damage. Posterior ankle arthroscopy was performed to examine intra-articular lesions. The patients were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle/hindfoot rating scale and sports activity score of the Self-Administered Foot Evaluation Questionnaire (SAFE-Q).
UNASSIGNED: The average reduced tibiofibular overlap on the standing mortise view was 1.2 mm (range, 0.5-2.0 mm) compared with the opposite ankles. Mason type 1 fracture was detected on CT in 6 patients, and ossification of the interosseous membrane was detected in 2 patients. A bone bruise in the posterior malleolus was observed on MRI in all but 1 patient. Intra-articular fragments located in the posterior ankle were observed and removed arthroscopically. Symptoms improved rapidly after arthroscopic treatment in all patients. All patients returned to rugby games at a median of 11 weeks postoperatively. The median AOFAS scores improved from 77 preoperatively to 100 postoperatively (P < .01), and the median SAFE-Q sports activity subscale score improved from 49.4 to 100 (P < .01).
UNASSIGNED: All unique intra-articular lesions that developed in rugby football players after syndesmosis injury were able to be treated arthroscopically. Patients returned to playing rugby football without syndesmosis reduction. Posterior ankle arthroscopy was effective in patients with residual symptoms after syndesmosis injury.

Posterior ankle impingement syndrome is mainly seen in ballet dancers and frequently associated with specific movements in ballet such as pointe and demi pointe in which the whole-body weight is applied to the maximally plantar flexed ankle. We performed arthroscopic debridement for 2 dedicated ballet dancers on the intervening soft tissue causing posterior ankle impingement syndrome (PAIS). In both cases, T2-weighted magnetic resonance imaging (MRI) revealed low-signal intensity of meniscus-like soft tissue without abnormal osseous findings, connecting from the posterior side of the talus to Kager\'s fat pad. To examine the intervening soft tissue in detail, we performed histological evaluation by hematoxylin and eosin staining, Safranin O fast green staining, and immunohistochemistry for type I collagen and type II collagen. Hematoxylin and eosin staining showed that there was cartilage-like tissue including chondrocyte-like cells in contact with fibrous tissue. The extracellular matrix in the cartilage zone was consistently stained by Safranin O staining and type II collagen without any staining with type I collagen. These findings suggested that the meniscus-like soft tissue appearing as low-signal intensity on MRI at the posterior side of talus included hyaline-like cartilage. To the extent of our knowledge, these were rare cases of hyaline-like cartilage generation causing PAIS in ballet dancers, which might be associated with ballet specific movements resulting in chondrogenesis.

OBJECTIVE: To report the prevalence of MRI features commonly associated with posterior ankle impingement syndrome in elite ballet dancers and athletes and to compare findings between groups.
METHODS: Thirty-eight professional ballet dancers (47.4% women) were age- and sex-matched to 38 elite soccer or cricket fast bowler athletes. All participants were training, playing, and performing at full workload and underwent 3.0-T standardised magnetic resonance imaging of one ankle. De-identified images were assessed by one senior musculoskeletal radiologist for findings associated with posterior ankle impingement syndrome (os trigonum, Stieda process, posterior talocrural and subtalar joint effusion-synovitis, flexor hallucis longus tendon pathology and tenosynovitis, and posterior ankle bone marrow oedema). Imaging scoring reliability testing was performed.
RESULTS: Posterior talocrural effusion-synovitis (90.8%) and subtalar joint effusion-synovitis (93.4%) were common in both groups, as well as the presence of either an os trigonum or Stieda process (61.8%). Athletes had a higher prevalence of either os trigonum or Stieda process than dancers (74%, 50% respectively, P = 0.03). Male athletes had a higher prevalence of either os trigonum or Stieda process than male dancers (90%, 50% respectively, P = 0.01), or female athletes (56%, P = 0.02). Posterior subtalar joint effusion-synovitis size was larger in dancers than athletes (P = 0.02). Male and female dancers had similar imaging findings. There was at least moderate interobserver and intraobserver agreement for most MRI findings.
CONCLUSIONS: Imaging features associated with posterior impingement were prevalent in all groups. The high prevalence of os trigonum or Stieda process in male athletes suggests that this is a typical finding in this population.

This article offers an overview of os trigonum syndrome, complications, operative techniques, and the authors\' preferred protocol. Os trigonum is an ossicle like many other ossicles in the foot and ankle. Individuals who require repetitive plantarflexion of the ankle for activity may develop symptoms of an enlarged os trigonum. Usually, symptoms will be isolated to the posteriolateral aspect of the ankle. Because of the normal anatomic route of the flexor hallucis longus tendon, its range of motion may also elicit pain to the posterolateral ankle. Conservative, as well as surgical including both endoscopic and open excision, has been described.

The aim of this study was to investigate the outcomes and complications after posterior ankle arthroscopy for the treatment of posterior ankle impingement syndrome, in a local population with a single surgeon series. Two-portal posterior ankle or hindfoot arthroscopy is an alternative option to open surgery in cases of posterior ankle impingement, that showed similar results but with less morbidity and faster recovery. There has been increasing interest in minimally invasive surgical techniques. Indications include extra- and intra-articular conditions and range from bony, cartilaginous to soft tissue pathology. Posterior ankle arthroscopy has been shown to be a good option in cases that are refractory to a period of conservative therapy. Posterior ankle arthroscopy also has known complications of sural nerve damage laterally and neurovascular bundle injury medially and also a steep learning curve that has been studied in the context of os trigonum excision. There have been few or no studies on the local Singaporean population and this article seeks to describe the various indications, results, and complications in the local Singaporean population by a single surgeon.Levels of Evidence: Level IV: Case series.

Posterior ankle impingement syndrome is common in sporting populations and encompasses a range of disorders that cause posterior ankle pain during maximal forced plantarflexion. The aim of this study was to evaluate the short- and medium- to long-term outcomes of 2-portal endoscopic surgery for osseous lesions causing posterior ankle impingement syndrome. This was a retrospective case series analysis of all patients who underwent 2-portal endoscopic surgery at a single institution between 2005 and 2016. Visual analogue scales and selected components of the Short Form of the Revised Foot Function Index were used to assess ankle function, with the median follow-up time being 4.8 years. Of the 52 patients, 49 (94%) were able to return to their previous sport/physical activity, with the mean time taken being 5.8 months. At the completion of follow-up, the mean pain score during exercise had improved from 7.5 to 0.9 points. The mean work and sporting function scores also improved, from 5.9 to 9.6 points and 2.9 to 8.8 points, respectively. The mean score of the Short Form of the Revised Foot Function Index also improved by 77.7 points, from 84.4 to 6.7 at the completion of follow-up. There were no postoperative infections or any other major complications. This study provides strong supporting evidence for the use of hindfoot endoscopy in the treatment of posterior ankle impingement syndrome in athletes.

The purpose of the present study was to quantify the learning curve for arthroscopic os trigonum excision using the log-linear model. Twenty-three consecutive feet underwent arthroscopic os trigonum excision and release of the flexor hallucis longus. The required time from the beginning of shaving of the soft tissue until completion of os trigonum excision and release of the flexor hallucis longus (van Dijk time) was recorded. Regression analysis was applied to predict the required time on the basis of the cumulative case volume after logarithmic transformation of both statistics. The mean required time was 35.2 (range 9 to 90) minutes. After logarithmic transformation, a significant linear correlation was observed between the required time and the cumulative case volume (p = .0043). The best-fit linear equation was calculated as log (y, estimated required time)  = -0.41 log (x, case volume) + 1.86, resulting in an estimated learning rate of 75.3% (= 2-0.41). The results showed an overall time reduction in arthroscopic os trigonum excision in support of a learning curve effect with an ~75% learning rate, indicating that the required time for arthroscopic os trigonum excision can decrease by ≤25% when the cumulative volume of cases has doubled.

Posterior ankle impingement syndrome (PAIS) is a clinical condition characterized by pain in the posterior aspect of ankle on performing activities requiring extreme plantar flexion. The impinging lesion could be bony and/or soft tissue. The operative treatment aims at removing the impinging lesion either by open or endoscopic surgery. The later has been shown to have benefits of early return to sports, better cosmesis, less wound complications. We report a case of a 19 year old footballer with PAIS secondary to Os Trigonum. The patient complained of pain on performing running and on kicking football. Conservative treatment in form of NSAIDS, rest, physiotherapy modality use could not ensure pain free return to sports.The patient was managed using endoscopic excision of the Os Trigonum followed by aggressive rehabilitation. The patient returned to competitive football at the end of 14 weeks after surgery. There were no wound complications. AAFOS score had changed from 73 to 100 and NPS scale showed pain score reduce from 7/10 to 1/10. We concluded that endoscopic management of PAIS to remove the impinging lesion is a minimally invasive technique that ensures early return to sports, good cosmesis, less risk of wound complications and good patient satisfaction.