Neurohistology of the sinus tarsi and sinus tarsi syndrome

Effect of amino functional groups on the surface properties and Lewis's acid base parameters of UiO-66(NH2) by inverse gas chromatography

Amino-functionalized metal organic frameworks (MOFs) have attracted much attention for various applications such as carbon dioxide capture, water remediation and catalysis. The focus of this study is to determine the surface and Lewis's acid-base properties of UiO-66(NH2) crystals by the inverse gas chromatography (IGC) technique at infinite dilution. The latter was applied to evaluate the dispersive component of the surface energy γ s d ( T ) by using thermal model and several molecular models. The obtained results proved that γ s d ( T ) decreases when the temperature increases. The best results were achieved by using the thermal model that takes into account the effect of the temperature on the surface areas of the organic molecules. We also observed a decrease of the Gibbs surface free energy of adsorption by increasing the temperature of the different organic solvents. The polar interactions of UiO-66(NH2) were obtained by using the methods of Saint-Flour Papirer, Donnet et al., Brendlé-Papirer and the different molecular models. The Lewis's acid base constants K A and K D were further calculated by determining the different variables of adsorption of the probes on the solid surface and the obtained values were 1.07 and 0.45 for K A and K D respectively, with an acid-base ratio (KA/KD) of 2.38. These values showed the high acidic surface of the solid substrate; whereas, the values of the entropic acid base parameters, ω A , ω D and ω A / ω D respectively equal to 1.0 × 10 - 3 , 3.8 × 10 - 4 and 2.73 , also highlighted the important acidity of UiO-66-(NH2) surface. These important findings suggest that the surface defects (missing linkers and/or clusters) in UiO-66(NH2) are the main determining factor of the acid-base properties of UiO-66 based structures.

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.

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.

Refractory peroneal spastic flat foot successfully treated with a cast in a girl

An 11-year-old girl presented with pain in the sinus tarsi and a foot deformity after spraining her left foot. She had flat foot due to spasticity of the peroneal tendon, which was difficult to correct manually. An imaging study revealed an accessory anterolateral talar facet (AALTF) and bone marrow oedema at the lateral aspect of the posterior talocalcaneal joint. We diagnosed peroneal spastic flat foot with possible involvement of sinus tarsi syndrome and AALTF. When conservative therapy failed, we applied a cast with the foot in full plantar flexion and an inverted position. After 4 weeks, the patient had a normal range of motion in the foot, the pain had resolved completely and the peroneal spasticity had disappeared. Orthopaedic treatment with a cast may be worth attempting before surgery in such cases.

Subtalar Arthroereisis for Surgical Treatment of Flexible Flatfoot

Various surgical techniques are known for the treatment of flexible flatfoot in children after failure of nonsurgical attempts. Data collected in a review of the last 10-year period (2010-2020) show that among the 691 feet undergoing subtalar arthroereisis with endorthesis, average age at surgery was 11.40 years and in the 1856 feet that underwent subtalar arthroereisis with calcaneo-stop 11.69 years, while the complications rate was 9.00% and 6.38%, respectively. These data confirm that subtalar arthroereisis with calcaneo-stop may have an advantage over subtalar arthroereisis with endorthesis as the screw is not placed across the subtalar joint but instead into the calcaneus.

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.

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.

Subacromial bursal preservation can enhance rotator cuff tendon regeneration: a comparative rat supraspinatus tendon defect model study

BACKGROUND

The role of subacromial bursa in rotator cuff surgery is unknown. This study aimed to assess the subacromial bursa's role in the healing of supraspinatus tendon injury in a rat model.

METHODS

Twenty-three male Sprague-Dawley rats (9 weeks old; weight, approximately 296 g) were used in this study. Three rats used as biomechanical study controls were killed at 12 weeks of age. A supraspinatus tendon defect was made bilaterally in 20 rats, whereas an additional subacromial bursa sectioning was performed on the left side. Six rats were killed for biomechanical testing and 4 were killed for histologic observation at 3 and 9 weeks, respectively.

RESULTS

The regenerated tendon in the bursal preservation group showed significantly superior biomechanical properties in maximum load to failure at 3 and 9 weeks and stiffness at 9 weeks after surgery compared with the bursal removal group. The modified Bonar scale scores showed better regenerated supraspinatus tendons in the bursal preservation group.

CONCLUSION

The present study found that the subacromial bursa plays an important role in rotator cuff regeneration in this rat supraspinatus injury model. Extensive bursectomy of the subacromial bursa may not be recommended in rotator cuff repair surgery, though future in vivo human studies are needed to confirm these observations.

Sinus Tarsi Syndrome: Diagnosed on 99mTc-MDP bone SPECT/CT

Sinus Tarsi Syndrome is a cause of chronic ankle instability and pain. MRI of the ankle has been the modality of choice for diagnosing the condition. However, SPECT-CT offers an alternate modality for diagnosing and evaluation of the condition. We present the case of a footballer who was suffering from chronic right leg pain despite receiving physiotherapy. He was being managed as a case of a chronic ankle sprain. Meanwhile, he was referred to the department as radiology for MRI of the ankle could not be performed as the patient felt claustrophobic. The patient subsequently underwent a ^99mTc-MDP Bone scan. He was diagnosed to be suffering from sinus tarsi syndrome as it showed a characteristic pattern noted on ^99mTc-MDP Bone scintigraphy. This case report reveals the potential of SPECT-CT as an alternative in the evaluation of chronic ankle sprain to MRI in segment of cases where MRI is not performed due to various reasons.

Operative Approaches to Ankle and Hindfoot Arthroscopy

The role of arthroscopy in the management of ankle and hindfoot pathology management has increased greatly in recent years with the potential for lower complication rates, faster recovery, improved access, and improved outcomes when compared to open techniques. Procedural variations exist as techniques aim to optimize lesion access, decrease operative time, and improve patient safety. Our goal is to summarize the described approaches and patient positionings common in minimally invasive arthroscopic surgery for anterior, lateral, and posterior ankle pathologies. A survey of pathology organized by arthroscopic approach and a review of recent advances in concomitant lesion management may be useful when planning arthroscopic foot and ankle surgery.

LEVEL OF EVIDENCE

Level V, expert opinion.

Vascular Compromising Effect of Drilling for Osteochondral Lesions of the Talus: A Three-Dimensional Micro-Computed Tomography Study

PURPOSE

To explore an optimal drilling depth and direction for osteochondral lesions of the talus based on a 3-dimensional vascular microarchitecture model constructed with micro-computed tomography (microCT).

METHODS

Twelve tali were perfused with the contrast agent and then scanned with microCT. The talar dome was divided into 9 zones, and the vessel densities were measured at the subchondral depths of 0 to 5 mm, 5 to 10 mm and 10 to 15 mm in each zone. The anterolateral (AL) and posterolateral (PL) approaches of retrograde drilling were simulated and the vascular compromising effect was evaluated.

RESULTS

The vessel density of the 0- to 5-mm depth was lower than that of the 5- to 10-mm (P = .001) and 10- to 15-mm (P = .007) depths, but no significant difference was found between the 5- to 10-mm and 10- to 15-mm depths (P > .9999). The vessel density in the 5- to 10-mm depth of medial talar dome was similar to that of the adjacent zones (P = .05). Vessel density in the 5- to 10-mm depth around the lateral talar dome was higher in the anterior and medial side. The anterolateral approach disturbed the main intraosseous vessels from the tarsal canal-tarsal sinus, causing extensive vascular compromise in the talus neck and body, whereas the posterolateral approach disturbed only the vessels near the tunnel.

CONCLUSIONS

The vessel density changed greatly from the subchondral 0- to 5-mm to the 5- to 10-mm depth. The vessel densities of the 5- to 10-mm depth around the medial talar dome were similar, whereas the anterior and medial side of the lateral talar dome was better vascularized. The posterolateral approach caused less vascular damage than the anterolateral approach.

CLINICAL RELEVANCE

The anterograde drilling depth was preferable to the subchondral 5- to 10-mm depth. There was no preferred drilling direction for the osteochondral lesion in the medial talar dome, whereas it is preferable to drill anteriorly or medially in the lateral dome. The posterolateral approach might be a safer alternative for retrograde drilling.

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.

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.

Bioabsorbable Calcaneo-Stop Implant for the Treatment of Flexible Flatfoot: A Retrospective Cohort Study at a Minimum Follow-Up of 4 Years

Arthroereisis of the subtalar joint is a common surgical technique in Europe for the management of flexible flatfoot in the pediatric population. In most cases, it is performed using a calcaneo-stop metallic screw. Despite the good clinical results, screw removal is always advised after 2 to 3 years. The use of a bioabsorbable screw might overcome the need for a second operation to remove a nonabsorbable device. We report the results of a biodegradable calcaneo-stop screw at a minimum of 4 years of follow-up. Eighty-eight procedures were performed on 44 children. All patients were clinically and radiologically evaluated preoperatively and at a minimum 4-year follow-up period. Patient satisfaction and plantar collapse using Viladot's classification were recorded. Meary's talus-first metatarsal angle and talocalcaneal angle were measured on radiographs preoperatively and at the last follow-up visit. The presence of the device at the last follow-up examination was assessed by magnetic resonance imaging. The mean follow-up duration was 56 months. Of the 44 patients, 33 (75%) reported excellent clinical outcomes, 9 (20.5%) good outcomes, and 2 (4.5%) poor. Foot print improvement was registered for all patients. The mean Meary's talus-first metatarsal angle had improved from 160.6° ± 7.7° preoperatively to 170.6° ± 6.5° at the last follow-up visit (p < .001). The talocalcaneal angle had decreased from 39.9° ± 5.2° preoperatively to 29.4° ± 4° at the last follow-up examination (p < .001). At the 4-year follow-up point, the implant could be seen to have almost completely biodegraded on magnetic resonance imaging. Two screw breakages occurred. The bioabsorbable calcaneo-stop screw seems to be an effective solution for flexible flatfoot in pediatric patients. Also, owing to its biodegradable composition, the need of a second operation for implant removal will not always be necessary.

[The talus stop screw arthroereisis for flexible juvenile pes planovalgus]

OBJECTIVE

Pain relief by realignment of the hindfoot and blocking excessive pronation through insertion of a screw into the lateral aspect of the calcaneus in juvenile pes planovalgus.

INDICATIONS

Symptomatic juvenile flatfoot (9-13 years).

CONTRAINDICATIONS

Congenital, fixed and secondary (neuromuscular disorder) flatfoot deformities.

SURGICAL TECHNIQUE

Incision at the lateral aspect of the sinus tarsi. Guide wire insertion into the lowest point of the lateral anterior calcaneus (fluoroscopy). Drilling (3.2 mm) and insertion of a 6.5-7.0 mm cancellous screw. The screw head impinges against the lateral aspect of the talus and prevents excessive eversion.

POSTOPERATIVE MANAGEMENT

Compression dressing. Full weight bearing allowed. No sports activity for 4 weeks.

RESULTS

Between 2002 and 2011, the technique was used in 35 children (68 feet; mean age 10 years). Complications were peroneal spasms, overcorrections, wound healing problems and local tenderness. Tarsometatarsal and calcaneal pitch angle improved significantly. The procedure is a reliable method for the correction of flexible juvenile flatfeet allowing "growth adjustment" of the subtalar joint.

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.

Comparative analysis of inter- and intraligamentous distribution of sensory nerve endings in ankle ligaments: a cadaver study

BACKGROUND

The aim of this study was to analyze the inter-, intraligamentous, and side-related patterns of sensory nerve endings in ankle ligaments.

METHODS

A total of 140 ligaments from 10 cadaver feet were harvested. Lateral: calcaneofibular, anterior-, posterior talofibular; sinus tarsi: lateral- (IERL), intermediate-, medial-roots inferior extensor retinaculum, talocalcaneal oblique and canalis tarsi (CTL); medial: tibionavicular (TNL), tibiocalcaneal (TCL), superficial tibiotalar, anterior/posterior tibiotalar portions; syndesmosis: anterior tibiofibular. Following immunohistochemical staining, the innervation and vascularity was analyzed between ligaments of each anatomical complex, left/right feet, and within the 5 levels of each ligament.

RESULTS

Significantly more free nerve endings were seen in all ligaments as compared to Ruffini, Pacini, Golgi-like, and unclassifiable corpuscles (P ≤ .005). The IERL had significantly more free nerve endings and blood vessels than the CTL (P ≤ .001). No significant differences were seen in the side-related distribution, except for Ruffini endings in right TCL (P = .016) and unclassifiable corpuscles in left TNL (P = .008). The intraligamentous analysis in general revealed no significant differences in mechanoreceptor distribution.

CONCLUSIONS

The IERL at the entrance of the sinus tarsi contained more free nerve endings and blood vessels, as compared to the deeper situated CTL. Despite different biomechanical functions in the medial and lateral ligaments, the interligamentous distribution of sensory nerve endings was equal.

CLINICAL RELEVANCE

The intrinsic innervation patterns of the ankle ligaments provides an understanding of their innate healing capacities following injury as well as the proprioception properties in postoperative rehabilitation.

[Options and limits of subtalar arthroereisis in childhood]

The minimally invasive subtalar screw arthroereisis procedure is becoming an increasingly more established option for treating juvenile flexible flatfoot. The procedure is indicated in children who are 9-13 years old and have idiopathic juvenile flexible flatfoot that has progressed to a symptomatic pathology. Minimally invasive subtalar screw arthroereisis functions by a combination of mechanical and proprioceptive effects that allow for growth adjustment of the subtalar joint and with a low complication rate. This surgical intervention is contraindicated for treating fixed and secondary pes plano valgus. The subtalar screw is removed once the pediatric foot has stopped growing and results in permanent correction of the flexible flatfoot.

The calcaneo-stop procedure

Flexible flatfoot is one of the most common deformities. Arthroereisis procedures are designed to correct this deformity. Among them, the calcaneo-stop is a procedure with both biomechanical and proprioceptive properties. It is designed for pediatric treatment. Results similar to endorthesis procedure are reported. Theoretically the procedure can be applied to adults if combined with other procedures to obtain a stable plantigrade foot, but medium-term follow up studies are missing.

The characteristics of the mechanoreceptors of the hip with arthrosis

Mechanoreceptors have been extensively studied in different joints and distinct signals that convey proprioceptive information to the cortex. Several clinical reports have established a link between the number of mechanoreceptors and a deficient proprioceptive system; however, little or no literature suggest concentration of mechanoreceptors might be affected by hip arthrosis. The purpose of this study is first to determine the existence of mechanoreceptors and free nerve endings in the hip joint and to distinguish between their conditions: those with arthrosis and without arthrosis. Samples of 45 male hips were analyzed: 30 taken from patients with arthrosis that were submitted to total arthroplasty and 15 taken from male cadavers without arthrosis. The patients' ages ranged from 38 to75 years (average 56.5) and the cadavers' ages ranged from 21 to 50 years (average 35.5). The capsule, labrum, and femoral head ligament tissues were obtained during the arthroplasty procedure from 30 patients with arthrosis and from 15 male cadavers. The tissue was cut into fragments of around 3 mm. Each fragment was then immediately stained with gold chloride 1% solution and divided into sections of 6 μm thickness. The Mann-Whitney test was used for two groups and the ANOVA, Friedman and Kruskal-Wallis tests for more than two groups. Results show the mechanoreceptors (Pacini, Ruffini and Golgi corpuscles) and free nerve endings are present in the capsule, femoral head ligament, and labrum of the hip joint. When all the densities of the nerve endings were examined with regard to those with arthrosis and those without arthrosis, the mechanoreceptors of cadavers without arthrosis were found to be more pronounced and an increase in free nerve endings could be observed (p = 0.0082). Further studies, especially electrophysiological studies, need to be carried out to clarify the functions of the mechanoreceptors in the joints.

Efficacy of MRI versus arthroscopy for evaluation of sinus tarsi syndrome

BACKGROUND

Magnetic resonance imaging (MRI) has been used to diagnose sinus tarsi syndrome (STS) because of its non-invasiveness and accuracy. The purpose of the present study was to evaluate the diagnostic efficiency of MRI compared with subtalar arthroscopy for STS.

MATERIALS AND METHODS

Twenty-eight patients (30 feet) who had undergone both MRI and subtalar arthroscopy for STS were evaluated. MRI results were compared with arthroscopic findings, which were considered the standard. Sensitivity, specificity, and positive and negative predictive values were calculated, and correlations between MRI and arthroscopic findings were investigated.

RESULTS

MRI was found to detect interosseous talocalcaneal ligament (ITCL) tears, cervical ligament (CL) tears, sinus tarsi fat alterations, and synovial thickening, with sensitivities, specificities, positive and negative predictive accuracies of: 44%, 60%, 85%, 18% (ITCL tears); 73%, 89%, 80%, 86% (CL tears); 71%, 92%, 93%, 71% (sinus tarsi fat alterations); and 86%, 87%, 67%, 95% (synovial thickening). Correlations between MRI and arthroscopic findings showed full agreement in 10%, partial agreement in 50%, and no agreement in 40%.

CONCLUSION

MRI is useful for detecting CL tears, sinus tarsi fat alterations, and synovial thickening, but is inadequate for correctly detecting ITCL tears.

Subtalar arthroscopy for sinus Tarsi syndrome: arthroscopic findings and clinical outcomes of 33 consecutive cases

PURPOSE

The purposes of this study were to identify the pathologic findings of sinus tarsi syndrome (STS) by subtalar arthroscopy and to evaluate the results of arthroscopic treatments in 33 consecutive cases.

METHODS

A retrospective review was performed in 31 consecutive patients (33 cases) who underwent subtalar arthroscopic treatment for STS. The mean follow-up duration was 24 months (range, 18 to 36 months). Patients were evaluated by use of arthroscopic findings (recorded on videotapes and photographs) and clinical outcomes, which included visual analog scale and American Orthopaedic Foot and Ankle Society ankle-hindfoot scores.

RESULTS

Arthroscopic findings showed partial tear of the interosseous talocalcaneal ligament in 29 cases (88%), synovitis in 18 (55%), partial tear of the cervical ligament in 11 (33%), arthrofibrosis in 8 (24%), and soft-tissue impingement in 7 (21%). The mean visual analog scale score improved from 7.3 points (range, 6 to 9 points) preoperatively to 2.7 points (range, 1 to 4 points) postoperatively (P < .005), and the mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score improved from 43.1 points (range, 21 to 65 points) preoperatively to 86.2 points (range, 72 to 100 points) postoperatively (P < .005). Of the cases, 16 (48%) had an excellent result, 13 (39%) had a good result, and 4 (12%) had a fair result.

CONCLUSIONS

Subtalar arthroscopy identified pathologies in the subtalar joint in patients with STS and showed that treatment of these pathologies led to improved function.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Histomorphometric evaluation of mechanoreceptors and free nerve endings in human lateral ankle ligaments

INTRODUCTION

Joint mechanoreceptors have been studied and most of investigators recognize the potential role of mechanoreceptors in the proprioceptive function of joint. The aim of this study was to analyze the general innervation and the possible existence of sensory receptors in the lateral ankle ligament.

METHODS

Lateral ankle ligaments including anterior talofibular, posterior talofibular and calcaneofibular were obtained from 24 ankles of 13 male cadavers with ages ranging from 18 to 65 (mean 41.6) years. Each ligament was divided into three parts according to the bony attachments (proximal, central, and distal segments). Histologically mechanoreceptors (Ruffini, Pacini and Golgi) and free nerve endings were identified, and classified. Histomorphometric determination and evaluation of the density of the area of the receptor was performed by the point-counting methods.

RESULTS

The anterior talofibular, posterior talofibular, and calcaneofibular ligaments were endowed with mechanoreceptor and free nerve endings. There was a significant prevalence of Pacini (p<0.001) compared with Ruffini and Golgi. However, there was no significant difference in the mechanoreceptors density in the different ligaments analyzed (p>0.05)

CONCLUSION

Innervation of the lateral ankle ligaments was confirmed in this study, suggesting that the presence of mechanoreceptors could have clinical implication as well as relevance in the proprioceptive function. Future electrophysiological studies will be required to define the role in the proprioceptive and nociceptive system of the ankle.

Retrograde drilling for osteochondral lesions of the talar dome

BACKGROUND

For the treatment of osteochondral lesions of the talar dome without detachment of the cartilage, there is little information on whether transmalleolar drilling or retrograde drilling is more effective in terms of clinical and morphologic evaluations.

HYPOTHESIS

Retrograde drilling may be more effective than transmalleolar drilling for lesions without cartilage detachment.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Subjects were 30 patients with lesions on 1 foot of grade 0 or I, determined according to a modified Pritsch classification system. Nineteen patients underwent transmalleolar drilling (TMD group), and 11 patients underwent retrograde drilling (RD group). Ankle arthroscopy was performed 1 year postoperatively to evaluate cartilage conditions.

RESULTS

Arthroscopic findings revealed that in the TMD group, 11 lesions (57.9%) were unchanged (grade I), and 8 lesions (42.1%) had deteriorated from grade 0 to I; in the RD group, 3 lesions (27.2%) had improved from grade I to 0, and 8 (72.8%) were unchanged (2 grade 0 lesions and 6 grade I lesions). There was a significant difference between the 2 groups in the distribution of cases that had improved, were unchanged, or had deteriorated (P < .0001).

CONCLUSIONS

This study showed that compared with transmalleolar drilling, retrograde drilling for osteochondral lesions of the talar dome can improve the arthroscopic assessment of the lesions.

Tarsal Sinus: Arthrographic, MR Imaging, MR Arthrographic, and Pathologic Findings in Cadavers and Retrospective Study Data in Patients with Sinus Tarsi Syndrome

PURPOSE

To evaluate the tarsal sinus by using different imaging techniques and specialized planes.

MATERIALS AND METHODS

Magnetic resonance (MR) imaging of the tarsal sinus was performed in 10 cadavers. Conventional arthrography of the anterior and posterior subtalar joints was then performed. Tarsal sinus ligaments were evaluated further on initial and reconstructed MR arthrograms along and perpendicular to their axes. Pathologic correlation was performed in five specimens suspected of having tarsal sinus lesions on the basis of initial imaging findings. In 37 patients with a clinical diagnosis of sinus tarsi syndrome, MR images of the ankle were obtained before and after intravenous gadolinium-based contrast material administration and were reviewed to verify the integrity of the tarsal sinus ligaments.

RESULTS

Two complete and three partial cervical ligament (CL) tears and one complete interosseous talocalcaneal ligament (ITCL) tear were diagnosed with MR imaging. Only one complete and one partial CL tear were seen after evaluation of both initial and reconstructed MR arthrograms and confirmed with pathologic correlation. In 18 patients, the diagnosis was confirmed at MR imaging, which depicted ITCL and CL tears in 11 patients, isolated CL tears in three patients, ganglia in three patients, and pigmented villonodular synovitis in one patient.

CONCLUSION

Cadaveric study results indicate that initial and reconstructed MR arthrograms along and perpendicular to the ligament axes are potentially useful for further evaluation of individual tarsal sinus structures.