Arthroscopic evaluation of the subtalar joint: does sinus tarsi syndrome exist?

Anterolateral and accessory anterolateral portals are safe to avoid subcutaneous nerve injury during subtalar arthroscopy-Definition of safe zones for standard lateral portals

PURPOSE

Injury to the superficial peroneal nerve (SPN) or the sural nerve (SN) is a common complication in subtalar arthroscopy. The purpose of this anatomical study was to evaluate the distance to surrounding subcutaneous nerves in the vicinity of three standard arthroscopic portals for subtalar joint arthroscopy and through actual portal placement for arthroscopic procedures, in order to define anatomical safe zones.

METHODS

Forty paired fresh-frozen foot-and-ankle specimens were used. Subtalar arthroscopy using a three-portal technique (anterolateral [AL], posterolateral [PL] and accessory anterolateral [AAL] portals) was performed. After completion of subtalar arthroscopy, the portals were marked, and all surrounding subcutaneous nerves, that is, the branches of the SPN and SN, were dissected. The distance of the nearest nerve at the level of the respective portal was measured and potential injury was recorded.

RESULTS

The nearest nerve at the level of the AL portal was the intermediate dorsal cutaneous nerve at a mean of 15.4 ± 5.1 mm medial to the portal. The nearest nerve at the level of the AAL portal was the lateral dorsal cutaneous nerve at a mean of 17.7 ± 4.8 mm, being lateral to the portal. The nearest nerve at the level of the PL portal was the SN at a mean of 6.7 ± 4.7 mm anterior to the portal. Based on the measurements, safe zones were defined.

CONCLUSIONS

Placement of the AL and AAL portals in subtalar arthroscopy is saved using standard anatomical landmarks and a thorough surgical technique. At the level of the PL portal, the SN is the most endangered structure in subtalar arthroscopy. Surgeons should be aware of the proximity of the SN to the PL portal and take the utmost care during portal placement and instrument insertion to avoid iatrogenic injury. The risk of nerve damage during portal placement may be reduced when positioning the portals in the defined safe zones.

LEVEL OF EVIDENCE

Not applicable.

Arthroscopic Anatomic Reconstruction of the Interosseous Talocalcaneal Ligament Using a Gracilis Autograft for Subtalar Instability: 6- to 12-Year Retrospective Follow-up

BACKGROUND

Several surgical techniques have been reported of subtalar instability (STI), but it remains a controversial topic without long-term clinical evidence. This study aimed to report the all-inside arthroscopic anatomic interosseous talocalcaneal ligament (ITCL) reconstruction technique and its long-term outcomes in STI patients with confirmed ITCL rupture.

METHODS

A retrospective study was conducted on consecutive series of STI patients who underwent all-inside arthroscopic anatomic reconstruction of the ITCL using a gracilis autograft between January 2010 and December 2016. The American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot scale, Karlsson-Peterson score, visual analog scale (VAS) pain score, and Tegner activity scale were assessed preoperatively and postoperatively. Furthermore, Foot and Ankle Ability Measure activities of daily living (FAAM-ADL) and sports (FAAM-Sports) scores, and whether patients returned to daily work, recreational activities, and preinjury sports were recorded at follow-up. Complications including postoperative sprain recurrence, range of motion (ROM) restriction, and incision numbness were evaluated at the final follow-up.

RESULTS

A total of 25 patients, with a mean age of 33.3 ± 8.8 years, were included in the follow-up analysis at a mean duration of 110.7 ± 20.4 months. The mean Karlsson-Peterson and AOFAS scores significantly increased from 61.8 ± 9.9 preoperatively to 93.8 ± 7.2 (P < .001) at the final follow-up and from 68.8 ± 7.4 to 95.1 ± 6.7 (P < .001), respectively. Additionally, the mean VAS pain score significantly decreased from 4.5 ± 1.1 to 0.6 ± 1.0 (P < .001). Regarding normal daily activities (FAAM-ADL), 22 patients (88%) obtained good to excellent (≥80) results; for sports-related activities, 18 patients (72%) had good to excellent FAAM-Sports scores and 19 patients (76%) returned to preinjury sports activities. Four patients (16%) reported mild to moderate ROM restrictions.

CONCLUSION

All-inside arthroscopic anatomic reconstruction of the ITCL demonstrated with gracilis autograft was associated with satisfactory long-term outcomes in restoring function and facilitating a return to sports for STI patients with ITCL injury.

The Evolution of Sinus Tarsi Syndrome-What Is the Underlying Pathology?-A Critical Review

Background and Objectives: Sinus tarsi syndrome (STS) is defined as pain located at the lateral opening of the tarsal sinus. The exact etiology of sinus tarsi syndrome is not completely understood. Some do not believe it to be a true pathology. This review aims to clarify the definition of sinus tarsi syndrome to better understand the underlying pathologies. We further propose an algorithm to evaluate sinus tarsi pain and provide advice for consecutive treatment options. Design: This is a narrative review. By searching PubMed, the available current literature was reviewed. Articles were critically analyzed to determine the pathoanatomy, biomechanics, and etiology of sinus tarsi pain. Algorithms for clinical evaluation, diagnosis, and treatment were also recorded. Finally, the authors approach to evaluating and treating sinus tarsi pain was included in this review. Results: Reviewing the available literature, STS seems to be a catch-all phrase used to describe any pain in this anatomic region. Many causes of sinus tarsi pain were listed, including impingement, subtalar instability, and many other pathologies around the ankle. Conclusions: A thorough evaluation of patients presenting with pain in the sinus tarsi or instability of the hindfoot is essential to determining the underlying cause. When the cause of pain is still not clear after clinical exam and radiologic assessment, subtalar arthroscopy can be helpful as both a diagnostic and treatment tool. We propose that the term of STS should be avoided and that a more accurate diagnosis be used when possible. Once a diagnosis is made, appropriate treatment can be initiated.

Posterior Arthroscopic Subtalar Joint Arthrodesis (Pasta)

The arthroscopic approach provides a manageable postoperative course in terms of wound healing, pain control, and bone healing when compared with an open procedure. In particular, posterior arthroscopic subtalar joint arthrodesis (PASTA) allows a reproducible and viable alternative to standard lateral-portal subtalar joint (STJ) arthrodesis without violating sinus or canalis tarsi neurovascular structures. Additionally, those patients who have undergone previous total ankle arthroplasty, arthrodesis, or talonavicular joint arthrodesis may be better served with PASTA over open arthrodesis if STJ fusion becomes necessary. This article describes the unique PASTA surgical procedure and its helpful tips and pearls.

Acute and Chronic Subtalar Joint Instability: Does It Really Exist?

Acute and chronic subtalar instability and commonly coexistent with other hindfoot pathology but can be difficult to diagnose. A high degree of clinical suspicion is required as most imaging modalities and clinical maneuvers are poor at detecting isolated subtalar instability. The initial treatment is similar to ankle instability, and a wide variety of operative interventions have been presented in the literature for persistent instability. Outcomes are variable and limited.

Sinus tarsi and sinus tarsi syndrome: An imaging review

The sinus tarsi is a funnel-shaped region at the junction of mid-foot and hind-foot which contains fat, vessels, nerves and ligaments. The ligaments help stabilise the subtalar joint and maintain the longitudinal arch of the foot. The nerve endings contain proprioceptive fibres indicating a role for the sinus tarsi in movement of the foot. Sinus tarsi syndrome is a clinical entity characterised by lateral hind-foot pain with worsening on palpation and weight-bearing, and perceived instability. It is associated with both traumatic and non-traumatic causes. Magnetic resonance imaging is the imaging modality of choice for assessment of the sinus tarsi and sinus tarsi syndrome. In this review article, we review the anatomy and various aetiologies of sinus tarsi syndrome, along with the imaging appearances.

Role of the intrinsic subtalar ligaments in subtalar instability and consequences for clinical practice

Subtalar instability (STI) is a disabling complication after an acute lateral ankle sprain and remains a challenging problem. The pathophysiology is difficult to understand. Especially the relative contribution of the intrinsic subtalar ligaments in the stability of the subtalar joint is still controversial. Diagnosis is difficult because of the overlapping clinical signs with talocrural instability and the absence of a reliable diagnostic reference test. This often results in misdiagnosis and inappropriate treatment. Recent research offers new insights in the pathophysiology of subtalar instability and the importance of the intrinsic subtalar ligaments. Recent publications clarify the local anatomical and biomechanical characteristics of the subtalar ligaments. The cervical ligament and interosseous talocalcaneal ligament seem to play an important function in the normal kinematics and stability of the subtalar joint. In addition to the calcaneofibular ligament (CFL), these ligaments seem to have an important role in the pathomechanics of subtalar instability (STI). These new insights have an impact on the approach to STI in clinical practice. Diagnosis of STI can be performed be performed by a step-by-step approach to raise the suspicion to STI. This approach consists of clinical signs, abnormalities of the subtalar ligaments on MRI and intraoperative evaluation. Surgical treatment should address all the aspects of the instability and focus on a restoration of the normal anatomical and biomechanical properties. Besides a low threshold to reconstruct the CFL, a reconstruction of the subtalar ligaments should be considered in complex cases of instability. The purpose of this review is to provide a comprehensive update of the current literature focused on the contribution of the different ligaments in the stability of the subtalar joint. This review aims to introduce the more recent findings in the earlier hypotheses on normal kinesiology, pathophysiology and relation with talocrural instability. The consequences of this improved understanding of pathophysiology on patient identification, treatment and future research are described.

Reconstruction of the cervical ligament in patients with chronic subtalar instability

PURPOSE

Diagnosis and treatment of subtalar instability (STI) remains complicated and challenging. The purpose of this study was to investigate the outcome of an anatomical reconstruction of the cervical ligament in patients with suspected chronic STI.

METHODS

This prospective study assessed the results of a surgical reconstruction of the cervical ligament using a gracilis tendon graft in a group of 14 patients (16 feet). Diagnosis of STI was performed using a predefined algorithm including clinical signs, MRI and peroperative evaluation. All patients had symptoms of chronic hindfoot instability despite prolonged non-surgical treatment. At final follow-up the outcome was assessed using the Karlsson score, the Foot and Ankle Outcome Score and the American Orthopaedic Foot and Ankle Society score.

RESULTS

After an average follow up of 22.6 months (range, 15-36), all patients reported significant improvement compared to their preoperative symptoms. The mean preoperative Karlsson score improved from 36.4 ± 13.5 (median 37, range 10-55) to a mean postoperative Karlsson score was 89.6 ± 8.5 (median 90, range 72-100) (P < 0.0001). The cervical ligament reconstruction was combined with other procedures in 13 cases: calcaneofibular ligament (CFL) reconstruction (3), CFL and anterior talofibular ligament reconstruction (7), bifurcate ligament reconstruction (3).

CONCLUSION

Anatomical reconstruction of the cervical ligament is a valid technique to treat patients with STI. It is a safe procedure and produces good clinical results with minimal complications. This technique can be considered in more complex cases and can be combined with other procedures according to the specific location of the instability.

LEVEL OF EVIDENCE

Level III.

A high rate of talocalcaneal interosseous ligament tears was found in chronic lateral ankle instability with sinus tarsi pain

PURPOSE

To evaluate the arthroscopic findings of subtalar joints, including interosseous talocalcaneal ligament (ITCL) tear, in patients with chronic lateral ankle instability (CLAI) and sinus tarsi pain.

METHODS

A total of 118 ankles (109 patients) having CLAI with sinus tarsi pain who had undergone subtalar arthroscopy and lateral ankle ligament surgery were evaluated. The medical records, radiologic images, and the arthroscopic images and videos were reviewed. ITCL tears were classified into 4 grades: grade 0 (no tear), grade 1 (mild), grade 2 (moderate), and grade 3 (severe). The efficacy of magnetic resonance imaging (MRI) in diagnosing ITCL tears was also evaluated by comparing preoperative official readings of MRI to arthroscopic findings. The pre- and postoperative functional scores were also assessed.

RESULTS

The overall tear rate of ITCL was 107/118 (90.7%). There were 29 ankles (23.6%) with grade 1, 42 ankles (35.6%) with grade 2, and 36 ankles (30.5%) with grade 3 tears. Isolated lateral ankle instability (LAI) was diagnosed in 43 ankles (36.4%), subtalar instability (STI) in 30 ankles (25.4%), and LAI with STI in 45 ankles (38.1%). There was a statistically significant relationship between the ITCL tear grade and the final diagnosis. ITCL tear was confirmed or suspected in 81 ankles (68.6%) on preoperative MRI. Pain Visual Analog Score and functional outcome scores including the American Orthopaedic Foot & Ankle Society and Karlsson-Peterson scores showed significant improvement after the surgery.

CONCLUSION

A high rate (90.7%) of ITCL tears was noted in CLAI patients with sinus tarsi pain. ITCL damage may play an important role in subtalar instability in patients with CLAI and sinus tarsi pain. Subtalar arthroscopic evaluation for ITCL tear is important for correct diagnosis for CLAI with sinus tarsi pain.

LEVEL OF EVIDENCE

IV.

Feasibility of MRI for the evaluation of interosseous ligament vertical segment via subtalar arthroscopy correlation: comparison of 2D and 3D MR images

Background

Interosseous ligament vertical segment (IOLV) and calcaneofibular ligament (CFL) have been reported to be important in stabilizing the subtalar joint. Unlike CFL, there is not much information regarding the comparison of MRI results with surgical evaluation of IOLV and the comparison between 2D and 3D MRI on IOLV evaluation. The feasibility of MRI in IOLV evaluation has yet to be reported. The purpose of this study was to evaluate the validity and reliability of MRI in IOLV tear detection via correlation with arthroscopic results. We also compared the diagnostic performance of 2D and 3D MR images.

Methods

In this retrospective study, 52 patients who underwent subtalar arthroscopy after ankle MRI were enrolled. Arthroscopic results confirmed IOLV tear in 25 cases and intact IOLV in 27 cases. Two radiologists independently evaluated the IOLV tears using only conventional 2D images, followed by isotropic 3D images, and comparison with arthroscopic results.

Results

Only the 2D sequences interpreted by two readers showed a sensitivity of 64.0–96.0%, a specificity of 29.6–44.4%, a positive predictive value of 51.6–56.4%, and a negative predictive value of 57.1–88.9%. Addition of isotropic 3D sequences changed the sensitivity to 60.0–80.0%, specificity to 63.0–77.8%, positive predictive value to 64.3–76.9%, and negative predictive value to 66.7–80.8%. The overall diagnostic performance of isotropic 3D sequences (AUC values: 0.679–0.816) was higher than that of 2D sequences (AUC values: 0.568–0.647). Inter-observer and intra-observer agreement between the two readers was moderate-to-good for both 2D and 3D sequences. The diagnostic accuracy in 19 patients with tarsal sinus fat obliteration tended to increase from 26.3–42.1% to 57.9–73.7% with isotropic 3D sequences compared with 2D sequences.

Conclusions

Isotropic 3D MRI was feasible for the assessment of IOLV tear prior to subtalar arthroscopy. Additional 3D sequences showed higher diagnostic accuracy compared with conventional 2D sequences in IOLV evaluation. Isotropic 3D sequences may be more valuable in detecting IOLV tear in case of tarsal sinus fat obliteration.

Current Concepts on Subtalar Instability

Subtalar instability remains a topic of debate, and its precise cause is still unknown. The mechanism of injury and clinical symptoms of ankle and subtalar instabilities largely overlap, resulting in many cases of isolated or combined subtalar instability that are often misdiagnosed. Neglecting the subtalar instability may lead to failure of conservative or surgical treatment and result in chronic ankle instability. Understanding the accurate anatomy and biomechanics of the subtalar joint, their interplay, and the contributions of the different subtalar soft tissue structures is fundamental to correctly diagnose and manage subtalar instability. An accurate diagnosis is crucial to correctly identify those patients with instability who may require conservative or surgical treatment. Many different nonsurgical and surgical approaches have been proposed to manage combined or isolated subtalar instability, and the clinician should be aware of available treatment options to make an informed decision. In this current concepts narrative review, we provide a comprehensive overview of the current knowledge on the anatomy, biomechanics, clinical and imaging diagnosis, nonsurgical and surgical treatment options, and outcomes after subtalar instability treatment.

Current concepts in sinus tarsi syndrome: A scoping review

INTRODUCTION

Sinus tarsi syndrome is a relatively unknown condition presenting with pain and a feeling of instability. We aim to summarise evidence on the aetiology, diagnosis and treatment of the condition, whilst answering the question of whether the term should be used.

METHODS

Scoping review following the methodological frameworks of Arksey and O'Malley, Levac and Peters. The review protocol is registered with the Open Science Framework: (https://osf.io/wj6ct/?view_only=59445d344ec34b6fab640d2fa7a83943).

RESULTS

In total, 605 studies were identified, 31 of which met selection criteria. Sinus tarsi syndrome is used to describe a range of distinct underlying pathologies. MRI and arthrography show non-specific abnormalities in patients and identifying underlying pathologies is challenging.

DISCUSSION

The distinct range of underlying pathologies makes identifying specific imaging abnormalities and optimal treatments difficult. Further research in determining optimal treatments for specific pathologies and investigating the efficacy of conservative treatment must be conducted, before we can justify a more specific diagnosis.

Accessory Talar Facet Impingement and Sinus Tarsi Pain Associated With Accessory Anterolateral Talar Facet

BACKGROUND

Sinus tarsi pain caused by accessory talar facet impingement (ATFI) owing to accessory anterolateral talar facet (AALTF) is not well documented. We evaluated prevalence of AALTF and differences of magnetic resonance imaging (MRI) findings between persons with and without sinus tarsi pain, and investigated the relevant association between MRI findings and sinus tarsi pain in persons with AALTF.

METHODS

We performed a case-control study on 120 ankles with sinus tarsi pain and 120 age- and gender-matched ankles without sinus tarsi pain. As MRI findings, bone marrow edema (BME), sinus tarsi fat obliteration (STFO), calcaneal cyst, talocalcaneal coalition, Gissane angle, talar inferolateral surface (TILS) angle, and calcaneal cortical thickness (CCT) were evaluated. The MRI findings were compared between persons with and without sinus tarsi pain, and between persons with and without AALTF. Among persons with AALTF, MRI findings were compared between those with and without sinus tarsi pain. Relevant association was evaluated between MRI findings and sinus tarsi pain in persons with AALTF.

RESULTS

Presence of AALTF, BME, and STFO were significantly higher in the group with sinus tarsi pain. The Gissane angle was significantly smaller, and the TILS angle and CCT were significantly larger in the group with sinus tarsi pain. The BME (OR 7.571, CI 1.453-39.446) and small Gissane angle (OR 0.891, CI 0.804-0.986) were significantly associated with sinus tarsi pain in persons with the AALTF.

CONCLUSION

The study provides evidence for ATFI related to impingement of an AALTF associated with talocalcaneal BME.

LEVEL OF EVIDENCE

Level III, case-control study.

AMIC for traumatic focal osteochondral defect of the talar shoulder: a 5 years follow-up prospective cohort study

BACKGROUND

Autologous Matrix-Induced Chondrogenesis (AMIC) is addressed to osteochondral defects of the talus. However, evidence concerning the midterm efficacy and safety of AMIC are limited. This study assessed reliability and feasibility of AMIC at 60 months follow-up. We hypothesize that AMIC leads to good clinical outcome at midterm follow-up.

METHODS

Surgeries were approached with an arthrotomy via malleolar osteotomy. A resorbable porcine I/III collagen membrane (Chondro-Gide®, Geistlich Pharma AG, Wolhusen, Switzerland) was used. Patients were followed at 24 and 60 months. The primary outcome of interest was to analyse the Foot Function Index (FFI), and the subscale hindfoot of the American Orthopaedic Foot and Ankle Score (AOFAS). Complications such as failure, revision surgeries, graft delamination, and hypertrophy were also recorded. The secondary outcome of interest was to investigate the association between the clinical outcome and patient characteristics at admission.

RESULTS

Data from 19 patients were included. The mean age at admission was 47.3 ± 13.2 years, and the mean BMI 24.1 ± 4.9 kg/m². 53% (10 of 19 patients) were female. At a mean of 66.2 ± 11.6 months, the FFI decreased at 24-months follow-up of 22.5% (P = 0.003) and of further 1.3% (P = 0.8) at 60-months follow-up. AOFAS increased at 24-months follow-up of 17.2% (P = 0.003) and of further 3.4 (P = 0.2) at 60-months follow-up. There were two symptomatic recurrences within the follow-up in two patients. There was evidence of a strong positive association between FFI and AOFAS at baseline and the same scores last follow-up (P = 0.001 and P = 0.0002, respectively).

CONCLUSION

AMIC enhanced with cancellous bone graft demonstrated efficacy and feasibility for osteochondral defects of the talus at five years follow-up. The greatest improvement was evidenced within the first two years. These results suggest that clinical outcome is influenced by the preoperative status of the ankle. High quality studies involving a larger sample size are required to detect seldom complications and identify prognostic factors leading to better clinical outcome.

LEVEL OF EVIDENCE

II, prospective cohort study.

Autologous Matrix Induced Chondrogenesis (AMIC) Compared to Microfractures for Chondral Defects of the Talar Shoulder: A Five-Year Follow-Up Prospective Cohort Study

Introduction: Many procedures are available to manage cartilage defects of the talus, including microfracturing (MFx) and Autologous Matrix Induced Chondrogenesis (AMIC). Whether AMIC or MFx are equivalent for borderline sized defects of the talar shoulder is unclear. Thus, the present study compared the efficacy of primary isolated AMIC versus MFx for borderline sized focal unipolar chondral defects of the talar shoulder at midterm follow-up. Methods: Patients undergoing primary isolated AMIC or MFx for focal unipolar borderline sized chondral defects of the talar shoulder were recruited prospectively. For those patients who underwent AMIC, a type I/III collagen resorbable membrane was used. The outcomes of interest were: Visual Analogic Scale (VAS), Tegner Activity Scale, American Orthopedic Foot and Ankle Score (AOFAS). The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) was assessed by a blinded radiologist, who had not been involved in the clinical management of the patients. Data concerning complication rate and additional procedures were also collected. Results: The mean follow-up was 43.5 months. The mean age of the 70 patients at operation was 32.0 years, with a mean defect size of 2.7 cm². The mean length of hospitalization was shorter in the MFx cohort (p = 0.01). No difference was found between the two cohorts in terms of length of prior surgery symptoms and follow-up, mean age and BMI, sex and side, and defect size. At a mean follow-up of 43.5 months, the AOFAS (p = 0.03), VAS (p = 0.003), and Tegner (p = 0.01) scores were greater in the AMIC group. No difference was found in the MOCART score (p = 0.08). The AMIC group evidenced lower rates of reoperation (p = 0.008) and failure (p = 0.003). Conclusion: At midterm follow-up, AMIC provides better results compared to MFx.

Modern Open and Minimally Invasive Stabilization of Chronic Lateral Ankle Instability

Chronic lateral ankle instability is the sensation of the ankle giving way along with recurrent sprains, chronic pain and swelling of the ankle for 1 year. The lateral ankle complex comprises the anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament. The anterior talofibular ligament is the most commonly injured ligament of the lateral ankle. Evaluation comprises a history and physical with concomitant imaging to confirm the diagnosis and can be used to evaluate for concurrent pathology. The most popular treatment is a direct anatomic repair; however, additional options can be used in specific patient populations.

Imaging Techniques for Assessment of Dynamically Unstable Sports Related Foot and Ankle Injuries

Foot and ankle instability can be seen both in acute and chronic settings, and isolating the diagnosis can be difficult. Imaging can contribute to the clinical presentation not only by identifying abnormal morphology of various supporting soft tissue structures but also by providing referring clinicians with a sense of how functionally incompetent those structures are by utilizing weight-bearing images and with comparison to the contralateral side. Loading the affected joint and visualizing changes in alignment provide clinicians with information regarding the severity of the abnormality and, therefore, how it should be managed.

Arthroscopic Evaluation of the Subtalar Joint: A Review and Survey of Pathology

BACKGROUND

A survey of pathology present in the subtalar joint by means of subtalar arthroscopy with anterolateral and middle portals has not been extensively explored in the literature. The focus of this study was to identify pathology in the subtalar joint with subtalar joint arthroscopy using this approach. We also compared these arthroscopic findings with those reported in the literature.

METHODS

We performed a retrospective review of 49 consecutive patients who had undergone 53 subtalar arthroscopic procedures. Data were obtained from intraoperative arthroscopic findings that were documented in the operative note or with arthroscopic photography. Additional procedures, including ankle arthroscopy, lateral ankle stabilization, and peroneal tendon repair, were recorded. Descriptive statistics were calculated and reported.

RESULTS

Subtalar arthroscopic examination revealed that all of the patients had intra-articular synovitis or adhesions present. Twenty-two procedures (42%) demonstrated subtalar joint instability, seven (13%) revealed chondromalacia, and one (2%) had an exostosis present. These observations are consistent with other reported findings in the literature.

CONCLUSIONS

This study found that the subtalar joint was most often affected by synovitis, adhesions, and instability in patients with symptomatic pathologies requiring subtalar arthroscopy. There was a relatively low incidence of chondromalacia or exostosis formation in the survey.

Secondary Effects of the Rupture and Reconstruction of the Interosseous Talocalcaneal Ligament on the Peritalar Joints

Background

The interosseous talocalcaneal ligament (ITCL) is the main soft-tissue contributor to subtalar joint stability. The role of ITCL reconstruction in retaining this stability is minimally reported. Therefore, we conducted this study to investigate the effects of rupture and reconstruction of the ITCL on the subtalar and peritalar joints.

Material/Methods

This experimental study randomly divided 72 rabbits into 3 equal groups of 24 rabbits each. Group I underwent reconstruction surgery, group II underwent resection, and group III was the control group. The cartilages between the talocrural and calcaneocrural joints, and between the subtalar and talonavicular joints on both sides were assessed by gross observation, ink staining, histology, and immunohistochemistry at weeks 4, 8, 16, and 32, postoperatively.

Results

In group II, the quantitative ink staining analysis revealed degeneration of the articular cartilages on the talonavicular joint (T=2.070, P=0.038) and the posterior subtalar joint (T=2.121, P=0.034) compared with the 2 sides of the same rabbit at 4 and 8 postoperative weeks. Comparing the operated sides of all the groups showed the posterior subtalar joints (Hc=9.563, P=0.008) and talonavicular joints (Hc=9.714, P=0.008) had an obvious difference at postoperative week 4; and in the calcaneocrural joints (Hc=6.750, P=0.034), it was noticed at postoperative week 8. Histology and immunohistochemistry findings confirm these observations.

Conclusions

An ITCL resection can lead to the progressive degeneration of the talonavicular and posterior subtalar joints, while an ITCL reconstruction can be beneficial in restoring the stability of these joints, preventing or postponing their degeneration, and protecting the articular cartilages.

Six out of ten patients with sinus tarsi syndrome returned to pre-injury type of sport after subtalar arthroscopy

PURPOSE

The purpose of this study was to determine multiple return to sport rates, long-term clinical outcomes and safety for subtalar arthroscopy for sinus tarsi syndrome.

METHODS

Subtalar arthroscopies performed for sinus tarsi syndrome between 2013 and 2018 were analyzed. Twenty-two patients were assessed (median age: 28 (IQR 20-40), median follow-up 60 months (IQR 42-76). All patients were active in sports prior to the injury. The primary outcome was the return to pre-injury type of sport rate. Secondary outcomes were time and rate of return to any type of sports, return to performance and to improved performance. Clinical outcomes consisted of Numerous Rating Scale of pain, Foot and Ankle Outcome Score, 36-item Short Form Survey and complications and re-operations.

RESULTS

Fifty-five percent of the patients returned to their preoperative type of sport at a median time of 23 weeks post-operatively (IQR 9.0-49), 95% of the patients returned to any type and level sport at a median time of 12 weeks post-operatively (IQR 4.0-39), 18% returned to their preoperative performance level at a median time of 25 weeks post-operatively (IQR 8.0-46) and 5% returned to improved performance postoperatively at 28 weeks postoperatively (one patient). Median NRS in rest was 1.0 (IQR 0.0-4.0), 2.0 during walking (IQR 0.0-5.3) during walking, 3.0 during running (IQR 1.0-8.0) and 2.0 during stair-climbing (IQR 0.0-4.5). The summarized FAOS score was 62 (IQR 50-90). The median SF-36 PCSS and the MCSS were 46 (IQR 41-54) and 55 (IQR 49-58), respectively. No complications and one re-do subtalar arthroscopy were reported.

CONCLUSION

Six out of ten patients with sinus tarsi syndrome returned to their pre-injury type of sport after being treated with a subtalar arthroscopy. Subtalar arthroscopy yields effective outcomes at long-term follow-up concerning patient-reported outcome measures in athletic population, with favorable return to sport level, return to sport time, clinical outcomes and safety outcome measures.

LEVEL OF EVIDENCE

IV.

The intrinsic subtalar ligaments have a consistent presence, location and morphology

BACKGROUND

Chronic subtalar instability is a disabling complication after acute ankle sprains. Currently, the literature describing the anatomy of the intrinsic subtalar ligaments is limited and equivocal which causes difficulties in diagnosis and treatment of subtalar instability. The purpose of this study is to assess the anatomical characteristics of the subtalar ligaments and to clarify some points of confusion.

METHODS

In 16 cadaveric feet, the dimensions and locations of the subtalar ankle ligaments were assessed and measured. CT-scans before dissection and after indication of the footprints with radio-opaque paint allowed to generate 3D models and assess the footprint characteristics.

RESULTS

The cervical ligament (CL) had similar dimensions as the lateral ligaments: anterior length 13.9 ± 1.5 mm, posterior length 18.5 ± 2.9 mm, talar width 13.6 ± 2.2 mm, calcaneal width 15.8 ± 3.7 mm. The anterior capsular ligament (ACaL) and interosseous talocalcaneal ligament (ITCL) were found to be smaller structures with consistent dimensions and locations.

CONCLUSION

This study identified consistent characteristics of the intrinsic subtalar ligaments and clarifies the local anatomical situation. The dimensions and footprints of the intrinsic ligaments of the subtalar joint suggest a more important role of the CL and ACaL in the stability of the subtalar joint. The results of this study are relevant to improve diagnostic tools and offer some guidelines when reconstructing the injured ligaments.

Surgical Treatment of Subtalar Joint Instability: Safety and Accuracy of a New Technique in a Cadaver Model

New surgical strategies to treat symptomatic subtalar joint (STJ) instability are evolving. We modified a previously described reconstruction strategy and then refined our new surgical technique through simulated surgery and subsequent cadaver dissections. Our purpose was to show that a tunnel intended to facilitate STJ stabilization surgery could safely be drilled across the footprints of the interosseous talocalcaneal ligament (ITCL). A percutaneous fluoroscopically guided tunnel for the purpose of ITCL reconstruction was created in 10 cadaveric below-knee specimens. Accuracy of the tunnel with relation to the anatomic boundaries of the ITCL attachment sites as well as damage to relevant structures at risk were recorded. Two sets of 5 surgeries were performed to assess for improvement in technique. Mean distances from the tunnel to the ITCL on the calcaneus improved between groups 1 and 2: 4.04 and 1.80 mm, respectively (p = .04). Mean distances from the tunnel to the ITCL on the talus improved between groups 1 and 2: 6.2 and 1.8 mm, respectively (p = .08). With information obtained from this study, an osseous tunnel can be safely placed within 2 mm of the ITCL footprints.

Does subtalar instability really exist? A systematic review

BACKGROUND

Subtalar joint instability (STI) is considered as a potential source of chronic lateral hindfoot instability. However, clinical diagnosis of STI is still challenging. This systematic review was conducted to assess the consistency of the clinical entity "subtalar instability", to investigate the reliability of available diagnostic tools and to provide a critical overview of related studies.

METHODS

A systematic review of the Medline, Web of Sciences and EMBASE databases was performed for studies reporting on tests to investigate subtalar instability or lesions of the subtalar ligaments. To investigate the relation with chronic STI, studies focusing on sinus tarsi syndrome (STS) or acute lesions of the subtalar ligaments were also included in the search strategy and were assessed separately.

RESULTS

This review identified 25 studies focusing on different topics: chronic STI (16), acute lesions of the subtalar ligaments (5) and STS (4). Twelve studies, assessing STI, demonstrated the existence of a subgroup with instability complaints related to abnormal increased subtalar motion (7) or abnormalities of the subtalar ligaments (6). We found insufficient evidence for measuring subtalar tilting using stress radiographs. MRI was able to assess abnormalities of the ligaments and stress-MRI detected abnormally increased motion.

CONCLUSION

Complaints of instability can be related to subtalar ligaments injuries and an abnormally increased motion of the subtalar joint. Stress radiographs should be interpreted with caution and should not have the status of a reference test. Clinical diagnosis should rely on several parameters including MRI.

Accessibility to Talar Dome in Neutral Position, Dorsiflexion, or Noninvasive Distraction in Posterior Ankle Arthroscopy

BACKGROUND

Osteochondral lesions of the talus are frequent pathologies of the ankle joint. Especially through arthroscopy, the treatment is kept as minimally invasive as possible. However, there are some drawbacks as to the reachability because of the high congruency of the ankle joint. Here, either noninvasive distraction or maximal dorsiflexion may be an option for better access to the lesion. The purpose of this study was to evaluate maximal dorsiflexion compared to neutral position or noninvasive distraction of the ankle joint in the arthroscopic reachability of the talar dome. The hypothesis of this study was that maximal dorsiflexion would allow for greater accessibility of the talar dome compared to neutral position or noninvasive distraction of the joint.

METHODS

Twenty matched pairs (n=40) of anatomical ankle specimens were used. The effects of neutral position, maximal dorsiflexion, and noninvasive distraction of the ankle joint on arthroscopic accessibility of the ankle joint were tested. After disarticulation of the talus, reach was measured and compared between the 3 positions.

RESULTS

In neutral position, 13.7±1.2 mm of the talar dome was reached laterally and 14.0±1.0 mm medially. In maximal dorsiflexion, the distance was 19.0±1.1mm laterally and 19.8±1.4 mm medially, and in noninvasive distraction it was 16.1±1.5 mm laterally and 15.7±1.0 mm medially. The statistical comparison showed a significantly better reach in dorsiflexion laterally (P = .003) and medially (P = .026).

CONCLUSION

Accessibility of the talar dome in maximal dorsiflexion was superior to that in neutral position or noninvasive distraction.

CLINICAL RELEVANCE

Results of this study may allow for better planning in arthroscopic treatment of osteochondral lesions of the talus.

Subtalar arthroscopic debridment for the treatment of sinus tarsi syndrome: case series

OBJECTIVE

The objective of this study is to report the results of arthroscopic debridement of the subtalar joint in eight patients with Sinus Tarsi Syndrome (STS) refractory to conservative treatment.

METHODS

This is a retrospective study of eight patients with STS who underwent subtalar arthroscopy for debridement of the sinus tarsi between January 2015 and January 2017 after six months of conservative treatment. All patients answered an epidemiological questionnaire and underwent functional evaluation with the Visual Analogue Pain Scale (VAS) and the American Orthopedic Foot and Ankle Society Score (AOFAS) in the preoperative and in the last evaluation (average of 12 months - 6-24 months).

RESULTS

All patients showed severe synovitis in the region. Seven patients had remnants of the talocalcaneal ligaments and six of the cervical ligament. AOFAS increased by 30 points on average (51.75 in the preoperative period to 82.62 in the last follow-up) and the VAS decreased on average by 5 points (7.37 preoperatively to 2.12 in the last follow-up). These results were statistically significant with p = 0.043 and p = 0.032 respectively. Six patients described the result as excellent and two as good. No complications were reported. All patients returned to sports after six months of follow-up.

CONCLUSION

The arthroscopic debridement of the subtalar joint is an effective and safe alternative in the treatment of STS refractory to conservative treatment. More studies, with a prospective methodology, are necessary to prove the results of this technique.

Anatomy of the Tarsal Canal and Sinus in Relation to the Subtalar Joint Capsule

BACKGROUND

Anatomical knowledge of the tarsal canal and sinus is still unclear owing to the complexity of the ligamentous structures within them, particularly the relationship with the capsules of the subtalar joints. The aim of this study was to examine the anatomical relationship between the fibrous tissues of the tarsal canal and sinus and the articular capsules of the subtalar joint.

METHODS

We conducted a descriptive anatomical study of 21 embalmed cadaveric ankles. For a macroscopic overview of the subtalar joint, we removed the talus in 18 ankles and separated the fibrous tissues from the surrounding connective tissues to analyze the layered relationship between the inferior extensor retinaculum (IER) and the subtalar joint capsule. Additionally, we histologically analyzed the tarsal canal and the medial and lateral sides of the tarsal sinus using Masson's trichrome staining in 3 ankles.

RESULTS

The medial and intermediate roots of the IER and interosseous talocalcaneal ligament (ITCL) were located in the same layer and were connected to each other, between the capsules of the posterior talocalcaneal and talocalcaneonavicular joints. The intermediate root of the IER and the cervical ligament (CL) had adjacent attachments on the tarsal sinus, and synovial tissues originating from the joint capsules filled the remaining area in the tarsal canal and sinus.

CONCLUSION

We determined that the tarsal canal and sinus tarsi contained 3 layered structures: the anterior capsule of the posterior talocalcaneal joint, including the anterior capsule ligament; the layer of ITCL and IER; and the posterior capsule of the talocalcaneonavicular joint, including the CL.

CLINICAL RELEVANCE

The results of this study may help with the understanding of the pathomechanism of subtalar instability and sinus tarsi syndrome, resulting in better treatment.

Arthroscopic treatment combined with the ankle stabilization procedure is effective for sinus tarsi syndrome in patients with chronic ankle instability

PURPOSE

This study aimed to investigate the results of arthroscopic treatment combined with ankle stabilization procedure for sinus tarsi syndrome (STS) in patients with chronic ankle instability (CAI).

METHODS

A total of 57 patients (31 males and 26 females, average age 29.9 ± 8.4 years ranging from 15 to 52 years) with STS and CAI who accepted operation from 2013 to 2015 were included in this retrospective study. Surgical procedures included thorough tarsal sinus debridement and repair or reconstruction of lateral ankle ligaments according to the quality of ligaments. American Orthopedic Foot and Ankle Society (AOFAS) score, Karlsson score, and Tegner score were evaluated preoperatively and at final follow-up.

RESULTS

All the patients accepted thorough debridement of tarsal sinus. Of these, 53 patients (93.0%) had an arch structure between the posterior subtalar joint and the middle subtalar joint. Further, 54 patients accepted lateral ankle ligament repair, and 3 patients accepted ligament reconstruction. A total of 40 patients were followed up with an average time of 30.7 months. The modified AOFAS score increased from 62.5 (27-90) to 93 (67-100), the Karlsson score increased from 57 (30-82) to 90 (55-100), and the Tegner score increased from 1 (1-3) to 5 (1-8).

CONCLUSIONS

Arthroscopic treatment combined with the ankle stabilization procedure could get satisfactory results for STS in patients with CAI. The arch structure composed by medial calcaneal component of the medial root of the inferior extensor retinaculum (MCC) might contribute to the pathological mechanism of STS.

LEVEL OF EVIDENCE

IV.

Update on Subtalar Joint Instability

Subtalar joint stability is ensured by the osseous geometry of the talocalcaneal joint and the complex array of the ligaments at the medial and lateral aspect of the ankle joint, the sinus and canalis tarsi, and the talocalcaneonavicular joint, respectively. There is still a substantial lack of knowledge about the interaction of the ankle and subtalar joint complex. Subtalar joint instability appears to be more frequent than is generally assumed. The diagnosis of chronic subtalar joint instability makes the application of a comprehensive algorithm necessary. There is ongoing debate about the preferable techniques for restoration of subtalar joint stability.

MRI evaluation of ligaments and tendons of foot arch in talar dome osteochondral lesions

Background There are no publications in literature describing an association between disorders of the ligaments and tendons supporting the foot arch and osteochondral lesions of the talus (OCLT). We believe there may be a correlation between the damage of these structures. Purpose To investigate the pathologies of main ligaments and tendons that support the foot arch in sprained ankles, by reviewing magnetic resonance imaging (MRI) studies and comparing the results in two groups of patients, with and without OCLT. Material and Methods MR images from 316 patients examined in the orthopedic clinic for ankle sprain were evaluated for pathologic findings of the plantar fascia, short and long plantar ligaments, spring ligament, sinus tarsi, and ankle tendons supporting the foot arch. Findings were compared between two groups of patients: 158 patients with OCLT and 158 patients without OCLT. Results Plantar fascia, short plantar ligament, and spring ligament abnormalities were seen in 50 (31.6%), 28 (17.7%), and 60 (38%) patients with OCLT, and in nine (5.6%), three (1.9%), and 18 (11.4%) patients without OCLT, respectively ( P < 0.05). Sinus tarsi and tendon abnormalities were seen in 11 (6.7%) and nine (5.7%) patients with OCLT, and in eight (5%) and eight (5%) patients without OCLT, respectively ( P > 0.05). Two or more associated abnormalities were present in 50 (31.6%) patients with OCLT and in 11 (6.7%) without OCLT ( P < 0.05). Conclusion Plantar fascia, short plantar ligament, and spring ligament abnormalities were commonly seen in patients with OCLT on MRI, while sinus tarsi and tendon abnormalities were not. Concomitant pathologies have an increased incidence in patients with OCLT.

X-shaped inferior extensor retinaculum and its doubtful use in the Bröstrom-Gould procedure

PURPOSE

The inferior extensor retinaculum (IER) is an aponeurotic structure located in the anterior aspect of the ankle. According to the literature, it can be used to reinforce a repair of the anterior talofibular ligament in ankle instability. Despite its usual description as an Y-shaped structure, it is still unclear which part of the retinaculum is used for this purpose, or if it is instead the crural fascia that is being used. The purpose of this study is to define the anatomical characteristics of the IER to better understand its role in the Broström-Gould procedure.

METHODS

Twenty-one ankles were dissected. The morphology of the IER and its relationship with neighbouring structures were recorded.

RESULTS

Seventeen (81%) of the IER in this study had an X-shaped morphology, with the presence of an additional oblique superolateral band. This band, by far the thinnest of the retinaculum, is supposed to be used to reinforce the repair of the anterior talofibular ligament. The intermediate dorsal cutaneous nerve (lateral branch of the superficial peroneal nerve) was found to cross the retinaculum in all cases.

CONCLUSIONS

The IER is most commonly seen as an X-shaped structure, but the fact that the oblique superolateral band is a thin band of tissue probably indicates that it may not add significant strength to ankle stability. Furthermore, the close relationship of the retinaculum with the superficial peroneal nerve is another factor to consider before deciding to perform a Broström-Gould procedure. These anatomical findings advise against the use of the Gould augmentation.

Subtalar instability: imaging features of subtalar ligaments on 3D isotropic ankle MRI

BACKGROUND

MRI analysis of subtalar ligaments in the tarsal sinus has not been well performed. We retrospectively investigated the appearance of subtalar ligaments using 3D isotropic MRI and compared imaging findings of subtalar ligaments between patients with subtalar instability (STI) and controls.

METHODS

Preoperative MRIs of 23 STI patients treated with arthroscopic subtalar reconstruction were compared to MRIs of 23 age- and sex-matched control subjects without STI. Thickness and width of anterior capsular ligament (ACL) and interosseous talocalcaneal ligament (ITCL) as well as thickness of calcaneofibular ligament (CFL) and anterior talofibular ligament (ATFL) were measured. Abnormalities in ACL, ITCL, CFL, ATFL, cervical ligament, and inferior extensor retinaculum were analyzed.

RESULTS

STI patients had significantly smaller ACL thickness and ACL width than controls (ACL thickness: 1.73 mm vs. 2.22 mm, p = 0.007; ACL width: 7.21 mm vs. 8.80 mm, p = 0.004). ACL thickness of ≤2.1 mm had a sensitivity of 66.7% and a specificity of 66.7% for diagnosis of STI. ACL width of ≤7.9 mm had a sensitivity of 80.0% and a specificity of 76.2% for the diagnosis of STI. However, thickness and width of ITCL, thickness of CFL, or thickness of ATFL was not significantly different between the two groups. Absence or complete tear of ACL was significantly more frequent in STI patients than that in controls (34.8% vs. 8.7%, p = 0.035). Complete tear of CFL and ATFL was more common in STI patients than that in controls, although the difference between the two groups was not statistically significant. Abnormalities of ITCL, cervical ligament, or inferior extensor retinaculum were not significantly different between the two groups.

CONCLUSIONS

MRI features of thin or narrow ACLs may suggest STI. Absence or complete tear of ACL was significantly more common in STI patients than that in controls.

MR imaging as a problem solving tool in posterior ankle pain: A review

Posterior ankle pain is a cause of chronic pain and disability, afflicting a wide range of individuals. While proper identification of the cause is essential for timely and adequate treatment, identifying the cause and excluding mimickers is often challenging for the physician due to the complex nature of the joint. In addition, pathology that can cause posterior ankle pain may occur on their own or in co-existence. Clinical conditions that can present as posterior ankle pain include: posterior ankle impingement, Achilles tendon pathology, medial flexor tendon pathology, peroneal pathology, retrocalcaneal bursitis, posterior subtalar tarsal coalition, sinus tarsi, and tarsal tunnel syndrome. In this review we introduce current concepts of pathophysiology in the main conditions involved in posterior ankle pain, and review the role of MR in the diagnosis and management of each condition. When pathology can be detected earlier and with more specificity, appropriate and time-sensitive treatment can be commenced, thus improving clinical outcomes.

Identification of the superficial peroneal nerve: Anatomical study with surgical implications

PURPOSE

To prevent iatrogenic damage to the superficial peroneal nerve during ankle arthroscopy, it needs to be identified. The purpose of the present study was to determine which clinical test identified the superficial peroneal nerve most frequently and which determinants negatively affected the identification.

METHODS

A total of 198 ankles (99 volunteers) were examined for identification of the superficial peroneal nerve. Race, gender, body mass index (BMI), shoe size and frequency of physical activity were collected.

RESULTS

The best method to identify the superficial peroneal nerve was the maximal combined ankle plantar flexion and inversion test. In this position, the nerve was identified in 57% of the ankles by palpation. BMI was the only independently influential factor in the identification of the superficial peroneal nerve.

CONCLUSION

Since in nearly six out of the ten ankles the superficial peroneal nerve can be identified, it is advised to assess its anatomy prior to portal placement. A higher BMI negatively influences the identification of the superficial peroneal nerve.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Subtalar instability

Subtalar instability is a common clinical entity. Clinicians should have a high index of suspicion of this diagnosis in patients who have been diagnosed with chronic lateral ankle instability but have failed standard management and have continued pain in the sinus tarsi. As with ankle instability, nonoperative management is the initial mainstay of treatment. Operative management includes ligamentous reconstruction of key lateral stabilizers of the subtalar joint. Future research on this subject should be focused at improving diagnosis and recognition of this entity.

Subtalar arthroscopy: indications, technique and results

The emergence of subtalar arthroscopy has improved the understanding and accuracy of diagnosing several hindfoot pathologic conditions, in particular, sinus tarsi syndrome. Subtalar arthroscopy has evolved into a useful diagnostic and therapeutic tool. The surgeon's experience is still essential to achieve good results. This article reviews the clinical indications, surgical techniques, and outcomes of subtalar arthroscopy.

A push-pull distraction method for arthroscopic subtalar joint arthrodesis

Unlike ankle joint arthroscopy, distraction of the subtalar joint can be challenging. We introduce a powerful distraction method that can be used during an arthroscopic subtalar joint arthrodesis procedure using a "push-pull" technique. A fully threaded screw is used to push the talus while the calcaneus is pulled to distract the joint. The technique allows the surgeon to access the rather tight joint without disrupting a significant amount of the ligamentous and capsular structures. It also allows preservation of the vascular structures that supply the talus. The "push-pull" screw can also be converted to a second point of fixation at the end of the procedure.

Distribution of sensory nerve endings around the human sinus tarsi: a cadaver study

The aim of this study was to analyse the pattern of sensory nerve endings and blood vessels around the sinus tarsi. The superficial and deep parts of the fat pads at the inferior extensor retinaculum (IER) as well as the subtalar joint capsule inside the sinus tarsi from 13 cadaver feet were dissected. The distribution of the sensory nerve endings and blood vessels were analysed in the resected specimens as the number per cm(2) after staining with haematoxylin-eosin, S100 protein, low-affinity neurotrophin receptor p75, and protein gene product 9.5 using the classification of Freeman and Wyke. Free nerve endings were the predominant sensory ending (P < 0.001). Ruffini and Golgi-like endings were rarely found and no Pacini corpuscles were seen. Significantly more free nerve endings (P < 0.001) and blood vessels (P = 0.01) were observed in the subtalar joint capsule than in the superficial part of the fat pad at the IER. The deep part of the fat pad at the IER had significantly more blood vessels than the superficial part of the fat pad at the IER (P = 0.012). Significantly more blood vessels than free nerve endings were seen in all three groups (P < 0.001). No significant differences in distribution were seen in terms of right or left side, except for free nerve endings in the superficial part of the fat pad at the IER (P = 0.003). A greater number of free nerve endings correlated with a greater number of blood vessels. The presence of sensory nerve endings between individual fat cells supports the hypothesis that the fat pad has a proprioceptive role monitoring changes and that it is a source of pain in sinus tarsi syndrome due to the abundance of free nerve endings.

Extended indications for foot and ankle arthroscopy

Advances in foot and ankle arthroscopy have allowed surgeons to diagnose and treat a broadening array of disorders that were previously limited to open procedures. Arthroscopy of the posterior ankle, subtalar joint, and first metatarsophalangeal joint and tendoscopy can be used to address common foot and ankle ailments, with the potential benefits of decreased pain, fast recovery, and low complication rates. Posterior ankle and subtalar arthroscopy can be used to manage impingement, arthrofibrosis, synovitis, arthritis, fractures, and osteochondral defects. First metatarsophalangeal joint arthroscopy can address osteophytes, chronic synovitis, osteochondral defects, and degenerative joint disease. Tendoscopy is a minimally invasive alternative for evaluation and débridement of the Achilles, posterior tibial, flexor hallucis longus, and peroneal tendons.

Ligament structures in the tarsal sinus and canal

BACKGROUND

The concrete anatomy and functional characteristics of the subtalar ligaments have been a matter of debate that some believe has hampered the progress of clinical ligament reconstruction.

METHODS

In 32 fresh-frozen cadaver feet, the course of the inferior extensor retinaculum (IER) and other subtalar ligaments was carefully measured and photographed both from the portal of the tarsal sinus and from a posterior view.

RESULTS

The IER inserted inside the tarsal sinus and canal by means of 3 roots: a lateral, an intermediate, and a medial one. These roots, along with the tarsal canal, divided the subtalar space into 3 parts. In front of the IER and inside the tarsal sinus, the thick cervical ligament (CL) lay at a 45-degree angle to the calcaneus. Behind the IER and inside the posterior capsule, in most cases (25 of 32 specimens), the posterior capsular ligament (PCaL) lay directly in front of the posterior talocalcaneal facet. Inside the tarsal canal, the fan-shaped medial root of the IER spread from outside upper lateral to lower medial, and the interosseous talocalcaneal ligament (ITCL) ran from upper medial to lower lateral; fibers of these 2 ligaments blended tightly together to form a V-shaped ligament complex. Just anterior to this complex in some cases (20 of 32 specimens), a short narrow upright ligament, the tarsal canal ligament (TCL), was located behind the middle talocalcaneal joint.

CONCLUSION

The results of this study show that the CL is the primary ligament in the tarsal sinus and that the ITCL is a thin single band rather than a strong bilaminar ligament located inside the tarsal canal. Instead, the medial root of the IER is the primary ligamentous structure in the tarsal canal.

CLINICAL RELEVANCE

The anatomical description provided here may provide a more accurate theoretical foundation for clinical subtalar stability restoration.

Subtalar instability: diagnosis and treatment

Subtalar instability is challenging to diagnose. It rarely follows a complete subtalar dislocation, an event more likely to result in subtalar pain, stiffness, and arthritis. By history, subtalar instability can be suggested by the patient’s feeling of ankle instability, easy “rolling over,” and a need to look at the ground constantly when walking. Clinical measures for inversion and eversion do not accurately reflect isolated subtalar motion, as soft tissue and other joint motion confound the examination. Stress radiographs have high false positive rates. Magnetic resonance imaging can show injured or disorganized ligaments suggestive of recurrent subtalar strain, but are not dynamic studies and cannot alone diagnose instability. Operative treatment, when elected, should focus on determining the source of the problem. Generally direct repair of the lateral ligaments is sufficient. Bony malalignment should always be considered especially in the setting when previous ligament reconstruction has failed.

Subtalar joint arthroscopy

Subtalar joint arthroscopy can be performed on a wide array of pathology. The procedure has progressed from a diagnostic test to a reconstructive procedure. Although it is not as popular as ankle arthroscopy, it is becoming more commonly discussed in the literature and is part of many arthroscopy courses. Better education along with improved instrumentation will allow more foot and ankle surgeons to treat pathology of the subtalar joint with arthroscopic techniques. This will lead to improved outcomes and lower complication rates in treating that pathology.

Ganglia of the tarsal sinus: MR imaging features and clinical findings

PURPOSE

To analyze MR imaging and clinical findings associated with ganglia of the tarsal sinus.

MATERIALS AND METHODS

In a record search, ganglia of the tarsal sinus were retrospectively identified in 26 patients (mean age 48±16 years), who underwent MR imaging for chronic ankle pain. Images were reviewed by two radiologists in consensus for size and location of ganglia, lesions of ligaments of the ankle and the tarsal sinus, tendon abnormalities, osteoarthritis, osseous erosions and bone marrow abnormalities. Medical records were reviewed for patient history and clinical findings.

RESULTS

Ganglia were associated with the interosseus ligament in 81%, the cervical ligament in 31% and the retinacula in 46% of cases. Signal alterations suggesting degeneration were found in 85%, 50% and 63% in case of the interosseus ligament, the cervical ligament and the retinacula, respectively. Scarring of the anterior talofibular ligament and the fibulocalcaneal ligament was found in 68% and 72% of the patients, respectively, while only 27% of the patients recalled ankle sprains. Ganglia at the retinacula were highly associated with synovitis and tendinosis of the posterior tibial tendon (p<0.05).

CONCLUSION

All patients with ganglia in the tarsal sinus presented with another pathology at the ankle, suggesting that degeneration of the tarsal sinus may be a secondary phenomenon, due to pathologic biomechanics at another site of the hind foot. Thus, in patients with degenerative changes of the tarsal sinus, one should be alerted and search for underlying pathology, which may be injury of the lateral collateral ligaments in up to 70%.

Subtalar arthroscopy using a 2.4-mm zero-degree arthroscope: indication, technical experience, and results

The subtalar joint is complex. With the advent of smaller diameter arthroscopes, subtalar arthroscopy has become an important diagnostic and therapeutic tool for subtalar joint disorders. The objective of this study was to evaluate the outcome of patients who underwent arthroscopy for subtalar joint disorders using a 2.4-mm zero-degree arthroscope. In this prospective study, 6 patients who underwent subtalar arthroscopy from September 2008 to January 2009 in the authors' institution were included. The American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot scores were recorded preoperatively and at 3 and 6 months postoperatively. Mean +/- SD age was 45.5 +/- 16.2 years (range, 27.5-63.2). Postoperative diagnosis included arthrofibrosis, osteoarthritis, and osteochondral disease of the subtalar joint. Mean +/- SD AOFAS scores improved from 49.67 +/- 18.83 (range, 22-76) to 67.33 +/- 14.92 (range, 53-91) at 3 months (P = .03) and 75 +/- 19.74 (range, 54-100) at 6 months (P = .004). Subtalar arthroscopy using the 2.4-mm zero-degree arthroscope shows promising results in the diagnosis and treatment of subtalar pathologies. Patients have a significant improvement in their AOFAS hindfoot scores as early as 3 months and continue to improve subsequently. Usage of the zero-degree arthroscope allows the "instrumentation hand" to maneuver more easily in space and perform the operative procedure without getting in the way of the "camera hand." It can also save on inventory costs for centers that already have the zero-degree arthroscope. The role of specialized imaging is still unclear. Diagnosis of sinus tarsi syndrome should be historical with direct visualization of the joint revealing exact etiology.

Anterior ankle arthroscopy, distraction or dorsiflexion?

Anterior ankle arthroscopy can basically be performed by two different methods; the dorsiflexion- or distraction method. The objective of this study was to determine the size of the anterior working area for both the dorsiflexion and distraction method. The anterior working area is anteriorly limited by the overlying anatomy which includes the neurovascular bundle. We hypothesize that in ankle dorsiflexion the anterior neurovascular bundle will move away anteriorly from the ankle joint, whereas in ankle distraction the anterior neurovascular bundle is pulled tight towards the joint, thereby decreasing the safe anterior working area. Six fresh frozen ankle specimens, amputated above the knee, were scanned with computed tomography. Prior to scanning the anterior tibial artery was injected with contrast fluid and subsequently each ankle was scanned both in ankle dorsiflexion and in distraction. A special device was developed to reproducibly obtain ankle dorsiflexion and distraction in the computed tomography scanner. The distance between the anterior border of the inferior tibial articular facet and the posterior border of the anterior tibial artery was measured. The median distance from the anterior border of the inferior tibial articular facet to the posterior border of the anterior tibial artery in ankle dorsiflexion and distraction was 0.9 cm (range 0.7-1.5) and 0.7 cm (range 0.5-0.8), respectively. The distance in ankle dorsiflexion significantly exceeded the distance in ankle distraction (P = 0.03). The current study shows a significantly increased distance between the anterior distal tibia and the overlying anterior neurovascular bundle with the ankle in a slightly dorsiflexed position as compared to the distracted ankle position. We thereby conclude that the distracted ankle position puts the neurovascular structures more at risk for iatrogenic damage when performing anterior ankle arthroscopy.

The course of the superficial peroneal nerve in relation to the ankle position: anatomical study with ankle arthroscopic implications

Despite the fact that the superficial peroneal nerve is the only nerve in the human body that can be made visible; iatrogenic damage to this nerve is the most frequently reported complication in anterior ankle arthroscopy. One of the methods to visualize the nerve is combined ankle plantar flexion and inversion. In the majority of cases, the superficial peroneal nerve can be made visible. The portals for anterior ankle arthroscopy are however created with the ankle in the neutral or slightly dorsiflexed position and not in combined plantar flexion and inversion. The purpose of this study was to undertake an anatomical study to the course of the superficial peroneal nerve in different positions of the foot and ankle. We hypothesize that the anatomical localization of the superficial peroneal nerve changes with different foot and ankle positions. In ten fresh frozen ankle specimens, a window, only affecting the skin, was made at the level of the anterolateral portal for anterior ankle arthroscopy in order to directly visualize the superficial peroneal nerve, or if divided, its terminal branches. Nerve movement was assessed from combined 10 degrees plantar flexion and inversion to 5 degrees dorsiflexion, standardized by the Telos stress device. Also for the 4th toe flexion, flexion of all the toes and for skin tensioning possible nerve movement was determined. The mean superficial peroneal nerve movement was 2.4 mm to the lateral side when the ankle was moved from 10 degrees plantar flexion and inversion to the neutral ankle position and 3.6 mm to the lateral side from 10 degrees plantar flexion and inversion to 5 degrees dorsiflexion. Both displacements were significant (P < 0.01). The nerve consistently moves lateral when the ankle is manoeuvred from combined plantar flexion and inversion to the neutral or dorsiflexed position. If visible, it is therefore advised to create the anterolateral portal medial from the preoperative marking, in order to prevent iatrogenic damage to the superficial peroneal nerve.

Subtalar arthroscopic procedures for the treatment of subtalar pathologic conditions: 115 consecutive cases

Arthroscopic procedures of subtalar pathology has shown promising results in previous studies, but the number of patients was relatively small. This article describes our experience and evaluated the clinical outcomes of 115 patients treated with subtalar arthroscopy for a range of subtalar pathologies. One hundred fifteen patients were followed up for >1 year after undergoing a subtalar arthroscopic procedure. Mean patient age was 40 years, and mean follow-up period was 42 months. Preoperative diagnosis included sinus tarsi syndrome in 31 patients, degenerative arthritis in 30, calcaneal fracture in 15, arthrofibrosis in 10, os trigonum syndrome in 8, talar fracture in 5, talocalcaneal coalition in 7, and calcaneal tumor in 1. The clinically modified American Orthopaedic Foot and Ankle Society (AOFAS) and AOFAS ankle-hindfoot scales and patient satisfaction were evaluated. Thirty-one patients had subtalar synovitis and underwent synovectomy; 9 had mild degenerative disease and underwent debridement and chondroplasty; 6 had chondromalacia and underwent intra-articular shaving; 11 had a loose body removed; 10 underwent arthroscopic resection for arthrofibrosis; 8 had symptomatic os trigonum and underwent arthroscopic excision; 6 underwent excision and multiple drilling for an osteochondral lesion of the talus; and 26 had severe degenerative joint disease and underwent arthroscopic subtalar arthrodesis. The mean modified AOFAS ankle-hindfoot scale in the subtalar fusion group was increased from 33 points preoperatively to 84 points postoperatively (P< .005), and the mean AOFAS ankle-hindfoot scale in the other-than-fusion group increased from 69 points preoperatively to 89 points postoperatively (P<.005). Ninety-seven percent of patients were satisfied with the procedure, and there were no serious complications.