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.

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.

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.

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.

Ligaments of the os trigonum: an anatomical study.

PURPOSE: The aim of the study was to examine the ligaments of the os trigonum. METHODS: The ankle joint magnetic resonance imaging (MRI) of 104 patients with the os trigonum (experimental group) and 104 patients without the os trigonum (control group) were re-reviewed. The connections of the os trigonum and posterior talofibular ligament (PTFL), the fibulotalocalcaneal ligament (FTCL), the paratenon of the Achilles tendon, the posterior talocalcaneal ligament (PTCL), the osteofibrous tunnel of the flexor hallucis longus (OF-FHL) and the flexor retinaculum (FR) were studied. RESULTS: The os trigonum is connected to structures. The posterior part of the PTFL inserted on the os trigonum in 85.6% of patients, whereas in all patients in the control group, the posterior part of the PTFL inserted on the posterior talar process (p < 0.05). The connection of the PTCL was seen in 94.2% of patients in the experimental group, while it was seen in 90.4% of patients in the control group (p > 0.05). The connection to the FTCL in the experimental group was 89.4%, while in the control group, it was 91.3% (p > 0.05). The communication with the paratenon was seen more often in the control group compared to that in the experimental group (31.7% vs. 63.8%, p < 0.001). The FTCL was prolonged medially into the FR in 85.6% of patients in the experimental group and in 87.5% of patients in the control group (p > 0.05). The flexor hallucis longus (FHL) run at the level of articulation between the os trigonum 63.5% and the posterior process of the talus 25% and less often on the os trigonum 11.5%. CONCLUSION: The os trigonum is connected with all posterior ankle structures and more connections than previously reported.

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.

Geometrical characteristics of the symptomatic and non-symptomatic ossa trigona.

BACKGROUND: Posterior 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. METHODS: Patients 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. RESULTS: A 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). CONCLUSIONS: The 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 EVIDENCE: III.

Delayed diagnosis of posterior ankle impingement in pediatric and adolescent patients: does radiology play a role?

BACKGROUND: Posterior ankle impingement syndrome (PAIS) results from the pinching of anatomical structures in the posterior part of the ankle. OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Outcomes of a 2-Portal Endoscopic Technique for Osseous Lesions Resulting in Posterior Ankle Impingement Syndrome.

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.

Is there any effect of presence and size of os trigonum on flexor hallucis longus tendon lesions?

BACKGROUND: It was hypnotized that presence and larger size of os trigonum (OT) can affect flexor hallucis longus tendon (FHL), so tenosynovitis, degeneration and partial tear can be developed. METHODS: A total of 98 (Study group: 50, Control: 48) subjects included to study and compered status of FHL lesions. Sagittal length and axial width of OT were measured on MRI to determine effect of OT on FHL lesions and correlated with arthroscopic findings. RESULTS: FHL tenosynovitis (p: 0,025), degeneration (p: 0,01) and partial tear (p: 0.008) was identified statistically high in study group. Statistical analysis revealed that as length of OT increased, frequency of degeneration (p: 0.03) and partial tear (p: 0.00) of FHL increased. CONCLUSION: Analyzes were showed that the presence of os trigonum had an important role on the FHL pathologies. Additional finding of study was to demonstrate that possibility of FHL lesion increased as length of OT extended. LEVELS OF EVIDENCE: Level 3.

Os Conundrum: Identifying Symptomatic Sesamoids and Accessory Ossicles of the Foot.

OBJECTIVE. Sesamoids and accessory ossicles are frequently encountered normal osseous structures in the foot that may be an uncommon cause of pain. Familiarity with their imaging findings allows the radiologist to provide reassurance in normal cases and increase confidence when making the relatively uncommon diagnosis of a pathologic sesamoid or symptomatic ossicle. CONCLUSION. Image-guided injections targeted to the symptomatic ossicle can confirm the suspected diagnosis and predict therapeutic outcomes before surgical intervention.

Chronic lateral ankle instability increases the likelihood for surgery in athletes with os trigonum syndrome.

PURPOSE: The etiology and incidence of os trigonum syndrome in professional athletes is highly variable. There is a paucity of data to ascertain why some athletes evolve towards surgery whilst others remain asymptomatic. We hypothesized that a lateral ligament ankle injury would increase the likelihood for surgery in those athletes with os trigonum syndrome. METHODS: Eighty professional athletes with clinical and radiological signs of os trigonum syndrome were identified to ascertain the incidence of injury to the lateral ligamentous ankle complex (acute and chronic) by magnetic resonance imaging (MRI). This cohort was subdivided into 2 groups; a surgical (n = 40) and a non-surgical (n = 40) cohort. Surgical division was decided if (1) the clinical hyper-plantar flexion test was positive, (2) a positive diagnostic ultrasound-guided injection and (3) no improvement was observed after 6 weeks of conservative rehabilitation. RESULTS: From the surgical cohort, 37 players (94.1%) had a chronic lateral ankle ligament injury on MRI, whilst 3 players (5.9%) had an acute lateral ankle ligament injury. Binary logistic linear modelling revealed that having a chronic lateral ligament injury increases the likelihood of os trigonum syndrome surgery by ten times compared to those with an acute lateral ligament injury. CONCLUSION: Professional athletes with chronic lateral ligament ankle injury have an approximate ten times greater risk for os trigonum syndrome surgery compared to athletes with acute lateral ligament ankle injury. LEVEL OF EVIDENCE: IV.

Incidence of symptomatic os trigonum among nonathletic patients with ankle sprain.

PURPOSE: Os trigonum syndrome is a rare condition, often affecting athletes. A paucity of data exists on the incidence of os trigonum syndrome in nonathletic population. The study aimed to determine the incidence and clinical characteristics of os trigonum syndrome in nonathletic patients with sprained ankles. METHODS: The sample consisted of 798 adolescent and adult patients that attended the emergency department or Foot and Ankle Clinic with acute ankle sprain. Lateral and/or oblique lateral radiographs of the feet were screened for the presence of os trigonum in relation to age and gender. A cohort of 163 patients with os trigonum was followed up prospectively over a 48-month period to correlate the presence of the os trigonum with patient symptomatology. RESULTS: Os trigonum was found in 20.4% (163/798) of sprained ankles. Patients aged 18-35 exhibited most os trigonum [42.3% (69/163)], with higher incidence in females. 5.5% (9/163) of the os trigonum patients developed an os trigonum syndrome after a standard treatment of an ankle sprain [3.8% (3/78) of males and 7.1% (6/85) of females]. Females aged between 18 and 35 years had higher incidence of os trigonum syndrome compared to males of a similar age. CONCLUSION: Os trigonum syndrome should be suspected in nonathletic patients with an ankle sprain unresponsive to standard treatment. About 1.1% of acute ankle sprain patients develop an os trigonum syndrome. This finding can help identify the source of a patient's symptoms, leading to an accurate diagnosis, appropriate treatment and reducing the potential chronic symptoms.

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.

Quantification of the Learning Curve for Arthroscopic Os Trigonum Excision.

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.

Painful stress reaction in the posterior subtalar joint after resection of os trigonum or posterior talar process.

INTRODUCTION: The resection of os trigonum or posterior talar process as treatment for posterior ankle impingement is an established operation. However, the authors encountered several painful stress reactions in the posterior subtalar joint during follow-up resulting in persisting incapacity to do sports. METHODS: From March 2011 to July 2015, 29 patients with 30 feet were operated (22 endoscopic, 8 open resections). Average follow-up time was 43 ± 13 months. Complications were grouped into "none", "temporary disadvantage" and "permanent damage". The following radiographic parameters were measured: (1) length of posterior talar process or os trigonum, (2) length of the uncovered calcaneal joint surface after resection, (3) amount of resection. RESULTS: The rate of permanent damage was 13.3% (4 of 30 feet), and all four of these patients developed a painful stress reaction in the posterior subtalar joint. One temporary disadvantage (persistent pain for three months) was found. All patients with major complications showed retrospectively what we call the "risk configuration" -the radius of the talus ending within the subtalar joint. The length of the uncovered calcaneal joint surface was therefore significantly larger (6.4 mm ± 3.33) in feet with permanent damage than in feet without (1.06 mm ± 2.15, P < 0.001). CONCLUSION: The resection of os trigonum or posterior talar process has a complication rate of 13.3% with persisting inability to do sports due to painful stress reaction in the posterior subtalar joint. The only risk factor found was the "risk configuration". In such cases, the resection has to be made not anterior into the subtalar joint and patients have to be informed about this possible complication. STUDY DESIGN: Retrospective case series; Evidence Level 4.

Imaging of Ankle Impingement Syndromes.

Ankle impingement syndromes are a commonly encountered clinical entity seen in athletes, secondary to repetitive forceful microtrauma. Symptoms are related to impingement of osseous or soft tissue abnormalities in the ankle joint, in particular the tibiotalar joint, which may result in painful limitation of ankle movements. Imaging modalities, such as radiographs and magnetic resonance imaging, are very useful in diagnosing osseous and soft tissue abnormalities seen in different types of ankle impingement syndromes. This article reviews the classification of ankle impingement syndromes, their etiology, and clinical and radiological findings.

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.

Posterior Endoscopic Excision of Os Trigonum in Professional National Ballet Dancers.

Previous studies have compared the outcomes after open and endoscopic excision of an os trigonum in patients of mixed professions. No studies have compared the differences in outcomes between the 2 procedures in elite ballet dancers. From October 2005 to February 2010, 35 professional ballet dancers underwent excision of a symptomatic os trigonum of the ankle after a failed period of nonoperative treatment. Of the 35 patients, 13 (37.1%) underwent endoscopic excision and 22 (62.9%) open excision. We compared the outcomes, complications, and time to return to dancing. The open excision group experienced a significantly greater incidence of flexor hallucis longus tendon decompression compared with the endoscopic group. The endoscopic release group returned to full dance earlier at a mean of 9.8 (range 6.5 to 16.1) weeks and those undergoing open excision returned to full dance at a mean of 14.9 (range 9 to 20) weeks (p = .001). No major complications developed in either group, such as deep infection or nerve or vessel injury. We have concluded that both techniques are safe and effective in the treatment of symptomatic os trigonum in professional ballet dancers. Endoscopic excision of the os trigonum offers a more rapid return to full dance compared with open excision.