Os trigonum: a discussion of its role in posterior ankle impingement syndrome and a meta-analysis of its prevalence.

PURPOSE: the os trigonum is a supernumerary bone that may lead to posterior ankle impingement syndrome. The present study aims to assess the prevalence of this bone. METHODS: A meta-analysis regarding the presence of the os trigonum was performed. For this, the MEDLINE and SciElo databases were searched using "os trigonum" as the keyword. Only original articles, theses, books, dissertations, and monographs were included. Papers with a sample size of < 50 individuals were excluded. The data extracted from the articles were: the total sample size, the prevalence of the trigonum, the method of analysis, the region of the sample, and data regarding sex and side (left or right). Statistical analysis was performed using MedCalc Statistical Software version 14.8.1 (MedCalc Software bvba, Ostend, Belgium). The heterogeneity between the studies was assessed using the I² estimation and the Cochran Q test. For all analyses, a random effect was used and a value of p < 0.05 was considered significant. RESULTS: 249 papers were found, while 18 were included in the meta-analysis. A total of 17,626 ankles were included. The pooled prevalence of the os trigonum was 10.3% (95% CI 7-14.1%) in the present study. There was no significant difference regarding sex or side, while studies conducted in imaging exams showed a higher prevalence in comparison to cadaveric studies. CONCLUSION: Our results suggest that the os trigonum is relatively common. Knowledge of the prevalence of the os trigonum may help surgeons and clinicians diagnose posterior ankle impingement syndrome.

Effect of simultaneous bilateral surgery or simultaneous arthroscopic ankle lateral ligament repair in hindfoot endoscopic surgery for posterior ankle impingement syndrome in athletes.

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. CONCLUSION: 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. LEVEL OF EVIDENCE: III, retrospective case-control study.

Posterior Ankle Impingement: It's Not Only About the Os Trigonum.

Background: 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. Methods: 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. Results: 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). Conclusion: 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. Level of Evidence: Level III, retrospective comparative study.

The Utilization of Minimally Invasive Surgery for Os Trigonum Syndrome: A Systematic Review.

BACKGROUND: A symptomatic os trigonum is a common cause of posterior ankle pain that has been traditionally managed with open excision. Minimally invasive surgery (MIS) has been proposed as an alternative to open excision for improved outcomes and decreased complication rates; however, no systematic review to date has examined the utilization of MIS for a symptomatic os trigonum. PURPOSE: To examine patient outcomes, return to sport, and complications associated with MIS for a symptomatic os trigonum. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A systematic review was performed on February 22, 2023, using the PubMed, CINAHL, MEDLINE, and Web of Science databases from database inception until February 22, 2023, on the topic of MIS for a symptomatic os trigonum. RESULTS: Of 885 articles retrieved from an initial search, 17 articles (N = 435 patients) met full inclusion criteria. The mean age of the cohort was 26.01 ± 4.68 years, with a mean follow-up time of 34.63 ± 18.20 months. For patients treated with MIS, the mean preoperative American Orthopaedic Foot and Ankle Society (AOFAS) score was 55.85 ± 12.75, the mean final postoperative AOFAS score was 94.88 ± 4.04, the mean preoperative visual analog scale pain score was 7.20 ± 0.43, and the mean final postoperative visual analog scale score was 0.71 ± 0.48. The mean time to return to sport for patients undergoing MIS was 7.76 ± 1.42 weeks. MIS had an overall complication rate of 5.0%, the majority of which consisted of transient neurapraxia of the sural or superficial peroneal nerve. CONCLUSION: Minimally invasive management of a symptomatic os trigonum appears to be a viable alternative to open surgery in terms of outcomes, return to sport, and complication rates. More high-quality evidence will be required to definitely recommend minimally invasive approaches as the standard of care over open surgery.

The Relationship between Types of Os Trigonum and Findings of Conventional Ankle Magnetic Resonance Imaging: A Study Based on Three-Dimensional Magnetic Resonance Imaging.

This study aimed to investigate the dimensions and types of the os trigonum and evaluate their relationship with various pathologic conditions on the posterior ankle using ankle MRI images. A total of 124 non-contrast-enhanced ankle and foot MR images of 123 consecutive patients were included in this retrospective study. The images were presented randomly, and they contained no patient information. The MR images were retrospectively and independently reviewed by two reviewers with a fellowship-trained musculoskeletal radiologist. The images were classified as type I and II based on the ossicle's medial border overlying the talus's posterior process and the groove for the flexor hallucis longus tendon (FHL). The study revealed that patients with type II os trigonum had a longer transverse diameter of the ossicle than type I, and there were statistically significant differences. Detachment status tended to be less in type I than in type II os trigonum, and the differences between the groups were statistically significant. There were no significant differences between type I and II os trigonum regarding posterior talofibular ligament (PTFL) abnormality, bone marrow edema, FHL tenosynovitis, and posterior synovitis. The study concluded that the os trigonum is a common cause of posterior ankle impingement, and type II os trigonum has a longer transverse diameter of the ossicle than type I.

Posterior Ankle Impingement.

This article is devoted to managing posterior ankle impingement syndrome and its management using endoscopic to arthroscopic surgical instrumentation. The authors explore the critical anatomy, pathogenesis, and clinical examination. Operative techniques, including the approach, and instrumentation used, are outlined. The postoperative protocol is discussed. Finally, a literature review is provided, which also defines known complications.

Posterior Ankle Impingement Syndrome.

Posterior ankle impingement is typically seen in athletes, primarily dancers and soccer players, secondary to dynamic and repetitive push-off maneuvers and forced hyperplantarflexion. Posterior ankle impingement results from chronic, repetitive trauma to the posterior ankle capsule, flexor hallucis longus tendon, and/or os trigonum. It is important to perform a thorough workup by isolating and testing the posterior compartment muscles and obtaining proper imaging with radiographs to identify any osseous abnormalities and MRI to evaluate the soft tissue structures. Nonsurgical treatment includes activity modification, physical therapy, and steroid injections.

The double posteromedial portals endoscopy for posterior ankle impingement syndrome in athletes.

BACKGROUND: Posterior ankle impingement syndrome (PAIS) may result from flexor hallucis longus tendinopathy, compression of the posterior process of the talus from the presence of an os trigonum, soft-tissue impingement, or a combination of these. Posterior extra-articular endoscopy performed with the patient supine through the double posteromedial portals, with excision of adhesions, excision of the posterior process of the talus or an os trigonum, and decompression of the tendon of the flexor hallucis longus (FHL), can be used in athletes with PAIS. METHODS: Thirty-four athletes with PAIS in whom conservative management had failed underwent posterior ankle endoscopy in the supine position using the double posteromedial portals. The patients were assessed pre- and postoperatively using the American Orthopaedic Foot and Ankle Society hindfoot scale score, the Tegner scale, and the simple visual analogue scale. Time of surgery, return to sports, patient satisfaction, and complications were recorded and analysed. The average length of postoperative follow-up was 26.7 ± 12.6 (range 24 to 72) months. RESULTS: The mean Tegner activity scale score improved to 9 ± 0.2 postoperatively (p < 0.05), while the mean American Orthopaedic Foot and Ankle Society scale score improved to 96 ± 5.1 (range 87 to 100) postoperatively, with 29 of 34 patients (85.3%) achieving a perfect score of 100 (p < 0.05). The mean time to return to sports was 8.7 ± 0.7 (range 8 to 10) weeks. The complication rate was low, with no superficial wound infections or venous thromboembolism events; only two patients (5.9%) reported pain and tenderness by 3 months after the index procedure. CONCLUSION: Posterior ankle endoscopy for the resection of a posterior process of the talus or an os trigonum and decompression of the tendon of FHL is safe and allows excellent outcomes with low morbidity in athletes with PAIS.

Posterior ankle impingement syndrome and os trigonum relationship in children.

Objective: 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. Methods: Fifty-five children (4-16-years-old; 16 girls,) who underwent magnetic resonance imaging (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. Results: 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. Conclusion: 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.

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

PURPOSE: To 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 METHODS: A 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. RESULTS: Of 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. CONCLUSION: More 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.

The Prevalence of Accessory Ossicles, Sesamoid Bones, and Biphalangism of the Foot and Ankle: A Radiographic Study.

BACKGROUND: Accessory ossicles, sesamoid bones, and biphalangism of toes are the most common developmental variations of the foot. These bones may be associated with painful syndromes; however, their clinical importance is not well understood because the reported prevalence varies widely. Therefore, we aimed to investigate these variants in Turkish subjects. METHODS: A total of 1651 foot radiographs were retrospectively assessed. Radiographs of feet were examined regarding the prevalence, sex, and bilaterality of accessory ossicles, sesamoid bones, and biphalangism in Turkish subjects. RESULTS: Accessory ossicles (26.1%) and sesamoid bones (8%) were detected. The most common accessory ossicles were os trigonum (9.8%), accessory navicular bone (7.9%), and os peroneum (5.8%). Also, we detected os supratalare (0.48%), os calcanei secundarium (0.42%) os subfibulare (0.42%), os supranaviculare (0.36%), os vesalianum (0.30%), os subtibiale (0.24%), os intermetatarseum (0.12%), and os subcalcis (0.12%). We observed bipartite hallux sesamoid in 1.8% and interphalangeal sesamoid bone of the hallux in 0.7% of radiographs. Incidences of metatarsophalangeal sesamoid bones were found as 0.6%, 0.06%, 0.6%, and 5.8% in the second, third, fourth, and fifth digit, respectively. We observed biphalangeal toe in 0.5%, 1.7%, 3.5%, and 37.6% in the second, third, fourth, and fifth toe, respectively. CONCLUSION: This study is the first detailed report on the incidence of the most common variants of the foot and ankle in a wide-ranging patients' series in Turkish subjects. Our study's findings will contribute to reducing misdiagnosis. CLINICAL RELEVANCE: The results of this study may provide anatomical data that could help clinicians in the diagnosis and management of disorders that present with pain and discomfort in the feet. Knowledge of these variants is important to prevent misinterpreting them as fractures.

Two-Year Outcomes of Posterior Ankle Arthroscopy: A Case Series.

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.

Associations between clinical and imaging findings in posterior ankle impingement syndrome: a systematic review.

BACKGROUND: Posterior ankle impingement syndrome (PAIS) is a common and debilitating condition, commonly affecting people who participate in activities that involve repetitive ankle plantarflexion. The relationship between clinical and imaging findings in PAIS has not been established. PURPOSE: To investigate the relationship between clinical and imaging features in PAIS by reviewing the literature comparing symptomatic patients to asymptomatic controls. MATERIAL AND METHODS: A systematic literature search was performed to identify all English-language articles that compared imaging features in patients diagnosed with PAIS to imaging in an asymptomatic control group. RESULTS: A total of 8394 articles were evaluated by title and abstract, and 156 articles were read in full text. No articles compared imaging findings to an asymptomatic control group, thus no articles met the inclusion criteria. CONCLUSION: This systematic review found no published research that compared the imaging findings of people diagnosed with PAIS to asymptomatic people. Until this information is available, imaging features in people with posterior ankle impingement should be interpreted with caution.

Open Versus Endoscopic Surgical Treatment of Posterior Ankle Impingement: A Meta-analysis.

BACKGROUND: Surgical treatment of symptomatic posterior ankle impingement consists of resection of the bony impediment and/or debridement of soft tissue. Historically, open techniques were used to perform surgery with good results. However, since the introduction of endoscopic techniques, advantages attributed to these techniques are shorter recovery time, fewer complications, and less pain. PURPOSE: The primary purpose was to determine whether endoscopic surgery for posterior ankle impingement was superior to open surgery in terms of functional outcome (American Orthopaedic Foot & Ankle Society [AOFAS] score). The secondary aim was to determine differences in return to full activity, patient satisfaction, and complications. STUDY DESIGN: Systematic review and meta-analysis. METHODS: MEDLINE, EMBASE (Classic), and CINAHL databases were searched. Publication characteristics, patient characteristics, surgical techniques, AOFAS scores, time to return to full activity, patient satisfaction, and complication rates were extracted. The AOFAS score was the primary outcome measure. Data were synthesized, and continuous outcome measures (postoperative AOFAS score and time to return to full activity) were pooled using a random-effects inverse variance method. Random-effects meta-analysis of proportions using continuity correction methods was performed to determine the proportion of patients who were satisfied and who experienced complications. RESULTS: A total of 32 studies were included in this review. No statistically significant difference was found in postoperative AOFAS scores between open surgery (88.0; 95% CI, 82.1-94.4) and endoscopic surgery (94.4; 95% CI, 93.1-95.7). There was no difference in the proportion of patients who rated their satisfaction as good or excellent, 0.91 (95% CI, 0.86-0.96) versus 0.86 (95% CI, 0.79-0.94), respectively. No significant difference in time to return to activity was found, 10.8 weeks (95% CI, 7.4-15.9 weeks) versus 8.9 weeks (95% CI, 7.6-10.4 weeks), respectively. Pooled proportions of patients with postoperative complications were 0.15 (95% CI, 0.11-0.19) for open surgery versus 0.08 (95% CI, 0.05-0.14) for endoscopic surgery. Without the poor-quality studies, this difference was statistically significant for both total and minor complications, 0.24 (95% CI, 0.14-0.35) versus 0.02 (95% CI, 0.00-0.06) and 0.14 (95% CI, 0.09-0.20) versus 0.03 (95% CI, 0.01-0.05), respectively. CONCLUSION: We found no statistically significant difference in postoperative AOFAS scores, patient satisfaction, and return to preinjury level of activity between open and endoscopic techniques. The proportion of patients who experienced a minor complication was significantly lower with endoscopic treatment when studies of poor methodological quality were excluded.

A comprehensive study of the anatomical variations of the posterolateral tubercle of talus / Un estudio integral de las variaciones anatómicas del tubérculo posterolateral del talo

SUMMARY: The aim of our study was to determine the prevalence and the anatomical variations of the posterolateral tubercle of talus in relation to sex on CT imaging. A total of 1478 ankle CT scans was retrospectively reviewed for the different anatomical variants of the posterolateral tubercle of talus, the type and size of os trigonum. Normal sized lateral tubercle was found in 46.1 %, an enlarged posterolateral tubercle (Stieda's process) in 26.1 %, os trigonum in 20.5 % and almost absent tubercle in 7.3 %. A statistically higher prevalence of Stieda's process was found in males while os trigonum was higher in females (p0.05). The posterolateral tubercle of talus and its accessory ossicle, the os trigonum, could vary morphologically. The data of this study could be helpful in understanding the clinical problems that could be associated with some of these variants.

RESUMEN: El objetivo de nuestro estudio fue determinar la prevalencia y las variaciones anatómicas del tubérculo posterolateral del talo en relación con el sexo en la imagen de TC. Se revisaron retrospectivamente un total de 1478 TC de tobillo para las diferentes variantes anatómicas del tubérculo posterolateral del talo, el tipo y tamaño del os trigonum. Se encontró tubérculo lateral de tamaño normal en 46,1 %, tubérculo posterolateral (proceso de Stieda) en 26,1 %, os trigonum en 20,5% y tubérculo casi ausente en 7,3 %. Se encontró una prevalencia estadísticamente más alta del proceso de Stieda en los hombres, mientras que el os trigonum fue mayor en las mujeres (p 0,05) no se observaron diferencias significativas. El tubérculo posterolateral del talo y su osículo accesorio, el os trigonum, podrían originar problemas clínicos que podrían estar asociados con algunas de estas variantes.

Causes of delayed diagnosis of posterior ankle impingement in the pediatric and adolescent population.

PURPOSE: 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). CONCLUSION: 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.

Magnetic resonance imaging findings associated with posterior ankle impingement syndrome are prevalent in elite ballet dancers and athletes.

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. MATERIALS AND 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. CONCLUSION: 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.

Posterior Ankle Decompression With Os Trigonum or Stieda Process Resection in Dancers: Case Series Report and Review of the Literature.

This case series reports the outcome of posterior ankle decompression and os trigonum or Stieda process resection utilizing an open posterolateral approach in 54 professional, pre-professional, and dedicated recreational dancers. All procedures were performed by a single surgeon at the same facility between 2008 and 2018. The surgical technique is described in detail. Data related to results of the surgery were gathered via follow-up questionnaire and verified by referencing the patients' medical records. Outcomes were self-assessed in terms of categories ranging from excellent through moderate to poor. Eighty-nine percent of the dancers (N = 48 of 54) chose excellent or good, 11% (N = 6) chose moderate, and none selected poor. These results were compared with those achieved in 17 previous studies reporting the use of both open (posterolateral and posteromedial) and arthroscopic/endoscopic techniques in dancers. This comparison found similarly favorable reported outcomes, but also great variation in methodology for determining patient reported outcomes (PROs). While the preferred surgical technique for posterior ankle decompression remains controversial, the open posterolateral approach utilized in this series resulted in high expectation of return to dance with minimal complications. The need for a dancer-specific PRO tool is discussed.