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Haglund syndrome is a common cause of heel pain that can affect either young and middle-aged patients. When indicated, surgical treatment can be performed using an open, percutaneous or endoscopic technique. A high rate of complications rate, especially due to healing of skin incisions, has been reported by open techniques, for this reason minimally invasive procedures treating insertional Achilles tendinopathy has recently gained popularity. Endoscopy allows to perform several procedures such as bursectomy, calcaneoplasty, Achilles tendon reattachment with anchors and Flexor Hallucis Longus transfer. Aim of this work is to provide an update on existing endoscopic techniques for the Achilles tendon pathologies treatment. These techniques represent an important tool for the orthopedic surgeon when treating Achilles tendon pathologies.

The lateral ligament complex of the ankle has been extensively studied. Recently an anatomical study described a connection between anterior talofibular ligament inferior fascicle (ATFLif) and calcaneofibular ligament (CFL). The applicability and the mechanical role of these connections have not yet been studied and need to be clarified. The purpose of this study is to evaluate the connection between ATFLif and CFL through a dynamic measurement analysis. An anatomical study was performed in 13 fresh-frozen below-the-knee ankle specimens. Each specimen was dissected in a protocolized manner until the lateral ligaments were exposed. A complete injury to both ATFL’s fascicles was created in the proximal third of the ligament. A displacement transducer specifically design was inserted in the CFL and in the lateral part of the calcaneus to test its lengthening. A traction of 1 kg weight (9.8 N) was applied to ATFLif while the transducer measured the lengthening that this force created in the CFL. A total of 13 ankle specimens were carefully dissected. One specimen with signals of a prior traumatic injury of the ATFLif was excluded. A total of 12 specimens were included, 7 females and 5 males with an average age of 74 years (52–88 years). The right ankle was dissected in 6 specimens. ATFL was identified as a two-fascicled ligament in all cases. The fibers connecting the ATFLif and CFL were observed in all specimens. The displacement transducer showed lengthening in the CFL in all measurements with a median of 0.59 mm (SD ± 0.34). Connecting fibers between ATFLif and CFL are robust enough to transmit tension from one structure to the other. In the case of associated proximal lesions of the ATFLif and CFL, ligaments repair with a single suture may be considered. This can be applied in surgical procedures in patients with lateral ankle instability.

PurposeThe purpose of the present anatomical study was to define the exact morphology of the posterior fibulotalocalcaneal ligament complex (PFTCLC), both for a better orientation and understanding of the anatomy, especially during hindfoot endoscopy.MethodsTwenty-three fresh frozen specimens were dissected in order to clarify the morphology of the PFTCLC.ResultsIn all specimens, the ligament originated from the posteromedial border of the lateral malleolus between the posterior tibiofibular ligament (superior border) and the calcaneofibular ligament (CFL), (inferior border). This origin functions as the floor for the peroneal tendon sheath. The origin of the PFTCLC can be subdivided into two parts, a superior and inferior part. The superior part forms an aponeurosis with the superior peroneal retinaculum and the lateral septum of the Achilles tendon. From this structure, two independent laminae can be identified. The inferior part of the origin has no role in the aponeurosis and ligamentous fibres run obliquely to insert in the lateral surface of the calcaneus, in the same orientation as the CFL, but slightly more posterior, which was a consistent finding in all examined specimens. The PFTCLC is maximally tensed with ankle dorsiflexion and is located within the fascia of the deep posterior compartment of the leg.ConclusionsThe PFTCLC is part of the normal anatomy of the hindfoot and therefore should be routinely recognized and partly released to achieve access to the posterior ankle anatomical pathology, relevant for hindfoot endoscopy. The origin of the ligament complex forms the floor for the peroneal tendon sheath. The superior part of the origin plays a role in the formation of an aponeurosis with the superior peroneal retinaculum and the lateral septum of the Achilles tendon.

Surgeons management of osteochondral lesions of the talus (OLT) may be different to the published guidelines because not all treatment recommendations are feasible in every country. This study aimed to assess how OLT are managed worldwide by foot and ankle surgeons. A web-based survey was distributed to the members of 21 local and international scientific societies focused on foot and ankle or sports medicine surgery. Answers with a prevalence greater than 75% of respondents were considered a “main tendency”, whereas where prevalence exceeded 50% of respondents they were considered a “tendency”. A total of 1804 surgeons from 79 different countries returned the survey. The responses to 19 of 28 questions (68%) regarding management and treatment of OLT achieved a main tendency (> 75%) or a tendency (> 50%). Symptoms reported to be most suspicious for OLT were pain on weight-bearing (WB) and after activity (83%), deep localization of the pain (62%), and any history of trauma (55%). 89% of surgeons routinely obtain an MRI, 72% routinely get WB radiographs, and 50% perform a CT scan. When treated surgically, OLTs are managed in isolation by only 7% of surgeons, and combined with ligament repair or reconstruction by 79%; 67% report simultaneous excision of soft-tissue or bony impingements (64%). For lesions less than 10–15 mm in diameter, bone marrow stimulation (BMS) represents the first choice of treatment for 78% of surgeons (main tendency). No other treatment was recorded as a tendency. For lesions greater than 15 mm in diameter no tendencies were recorded. The BMS represented the most preferred treatment being the first choice of treatment for 41% of surgeons. OLT depth had little influence on treatment choice: 71% of surgeons treating small lesions and 69% treating large lesions would choose the same treatment regardless of whether the lesion had a depth lesser or greater than 5 mm. The management of OLT by foot and ankle surgeons from around the world remains extremely varied. The main clinical relevance of this study is that it provides updated information with regard to the management of OLT internationally, which could be used by surgeons worldwide in their decision-making and to inform the patient about available surgical options. Level IV.

Background: Both the percutaneous technique with arthroscopic assistance, also known as arthroscopic Broström (AB), and the arthroscopic all-inside ligament repair (AI) are widely used to treat chronic lateral ankle instability. The aim of this study was to compare the clinical outcomes of these 2 arthroscopic stabilizing techniques. Methods: Thirty-nine consecutive patients were arthroscopically treated for chronic ankle instability by 2 different surgeons. The AB group comprised 20 patients with a mean age of 30.2 (range, 18-42) years and a mean follow-up of 19.6 (range, 12-28) months. The AI group comprised 19 patients with a mean age of 30.9 (range, 18-46) years and mean follow-up of 20.7 (range, 13-32) months. Functional outcomes using the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score and visual analog pain scale (VAS) were assessed pre- and postoperatively. Range of motion (ROM) and complications were recorded. Results: In both groups the AOFAS and VAS scores significantly improved compared with preoperative values ( P < .001) with no difference ( P > .1) between groups. In the AB group the mean AOFAS score improved from 67 (range, 44-87) to 92 (range, 76-100) and the mean VAS score from 6.4 (range, 3-10) to 1.2 (range, 0-3). In the AI group the mean AOFAS score changed from 60 (range, 32-87) to 93 (range, 76-100) and the mean VAS score from 6.1 (range, 4-10) to 0.8 (range, 0-3). At the final follow-up 8 complications (40%) were recorded in the AB group. In the AI group 1 complication (5.3%) was observed ( P < .05). Conclusion: Both the AB and AI techniques are suitable surgical options to treat chronic ankle instability providing excellent clinical results. However, the AB had a higher overall complication rate than the AI group, particularly involving a painful restriction of ankle plantarflexion and neuritis of the superficial peroneal nerve. Level of Evidence: Level III, retrospective comparative study.

Background: Lateral release (LR) for the treatment of hallux valgus is a routinely performed technique, either by means of open or minimally invasive (MI) surgery. Despite this, there is no available evidence of the efficacy and safety of MI lateral release. Our aim was to study 2 popular techniques for MI LR in cadavers by subsequently dissecting the released anatomical structures. Methods: Twenty-two cadaveric feet were included in the study and allocated into 2 groups, 1 for each procedure: 1 group underwent a MI adductor tendon release (AR), and in the other group, an extensive percutaneous lateral release (EPLR) (adductor tendon, suspensory ligament, phalanx-sesamoid ligament, lateral head of flexor hallucis brevis, and deep transverse metatarsal ligament) was performed. Anatomical dissection was performed to identify neurovascular injuries and to verify the released structures. Results: Both techniques demonstrated to be effective in reproducing a MI LR. A satisfactory release of the adductor tendon was achieved equally in both techniques ( P = .85), being partial in most EPLR cases and full in the majority of AR cases. The EPLR was successful in releasing the intended additional structures ( P < .05). One case of inadvertent complete section of the flexor hallucis longus was identified in the percutaneous adductor tendon release group. No cases of dorsolateral nerve injury were seen with either of the techniques. Conclusion: Percutaneous lateral release was a reliable and accurate technique in this cadaveric model. The MI AR proved to be more effective in fully releasing the adductor tendon while the ER was intended and able to release a number of other structures. Clinical Relevance: MI LR is a safe procedure that could obviate the need for open surgery to achieve the same surgical goal. It can be associated to either open or MI osteotomies in the correction of hallux valgus.

Purpose: The anterior tibiofibular ligament (ATiFL) and its distal fascicle have been the subject of numerous studies, mainly due to the involvement of this ligament in anterolateral soft-tissue impingement of the ankle. There is currently no firm evidence related to the incidence of the distal fascicle or the frequency with which it is in contact with the talus, or whether this is a constant anatomic finding. In addition, the terminology used to refer to this structure is not accurate and varies widely in previous studies. The purpose of this study was to perform an anatomic study on a large number of specimens to clarify the anatomy of the anterior tibiofibular ligament, and specifically its distal fascicle, and its possible role in anterior ankle impingement syndrome. Methods: During a 7-year period (2010–2016), cadaveric ankle specimens dissected at our Anatomy Department were included in this study, accounting for a total of 154 ankles. The incidence of the distal fascicle and its contact with the talus were documented. Results: One hundred and seventeen ankles were included [78 men, 39 women, with a median age of 79.3 years (range 51–100 years)]. The ATiFL was found to have a distal fascicle in 100% of ankles, contacting the anterolateral part of the talus in all cases. The contact was increased in plantarflexion and reduced in dorsiflexion and finally disappeared completely in maximum dorsiflexion. Conclusions: The ATiFL has a constant distal fascicle that is in contact with the talus in the neutral position and in plantar flexion. Contact disappears in maximum dorsiflexion.

Purpose: A thorough understanding of the arthroscopic anatomy is important to recognise pathological conditions. Although some ankle ligaments have been described as intra-articular structures, no studies have assessed the full visibility of these structures. The purpose of this study was to assess arthroscopic visibility of medial and lateral ankle collateral ligaments. Methods: Arthroscopy was performed in 20 fresh frozen ankles. The arthroscope was introduced through the anteromedial portal and the anterior compartment was explored in ankle dorsiflexion without distraction. Intra-articular structures were tagged using a suture-passer introduced percutaneously and they were listed in a table according to the surgeon’s identification. After the arthroscopic procedure, the ankles were dissected to identify the suture-tagged structures. Results: According to the suture-tagged structures, 100% correlation was found between arthroscopy and dissection. In the anterior compartment, the superior fascicle of the anterior talofibular ligament, the distal fascicle of the anterior tibiofibular ligament and the anterior tibiotalar ligament on the medial side were observed. The deep fascicle of the posterior tibiofibular ligament and the intermalleolar ligament were tagged at the posterior compartment. Conclusion: Ankle dorsiflexion and non-distraction arthroscopic technique allows full visualisation of the medial and lateral ankle collateral ligaments: the superior fascicle of the anterior talofibular ligament, the distal fascicle of the anterior tibiofibular ligament and the anterior tibiotalar ligament. When using distraction, posterior structures as the deep fascicle of the posterior tibiofibular ligament and the intermalleolar ligament can be observed with anterior arthroscopy.

A deep knowledge of lateral ankle ligaments is necessary to understand its function, pathophysiology and treatment options. The ankle lateral collateral ligament is formed by the anterior talofibular ligament (ATFL), the calcaneofibular (CFL) and the posterior talofibular ligament (PTFL). Although previous studies have reported connections between these ligaments on its lateral side, no studies have specifically assessed connections on the medial side. The aim of this study was to assess the morphology and consistency of the medial connections between the components of the lateral collateral ligament complex of the ankle. Forty fresh-frozen ankle specimens were dissected to look for connections between the three lateral ankle ligaments. After visualization of the lateral ligaments was achieved, the fibula was amputated and ligament insertions were released at the talar and calcaneal insertion points. Observation of the connections and video analysis of the dynamic relationships of ligament connections were performed. Connections were found in all cases between the ATFL and PTFL, the ATFL and CFL, and the CFL and PTFL. Connections between ATFL and PTFL were not homogeneous. Although connections between the ATFLif and PTFL were noted in all cases (40), only 17 ankles (42.5%) had connections between the ATFLsf and PTFL. The amount of fibres of connection was also variable. Connections between the three components of the lateral collateral ligament of the ankle may be observed from the medial aspect of the ankle, and this may have important implications for arthroscopic lateral ligament repair.

An increased interest in ankle instability has led to description of new concepts such as ankle microinstability or rotational ankle instability and the development of new arthroscopic techniques treating ankle instability. Ankle instability is constantly associated to intraarticular pathologies that contribute to generate pain and dysfunction. Arthroscopy plays an important role in identifying and treating all intraarticular abnormalities including ligament injuries. Despite a few studies are available in literature on arthroscopic treatment of medial collateral ligament injury, an arthroscopic all-inside repair of lateral and medial ankle ligaments has been proposed showing promising clinical results.

Purpose: Despite the increased use of ankle dorsiflexion without distraction, no reports have specifically addressed the arthroscopic anatomy of the ankle in this position. The purpose of this study was to describe the normal arthroscopic anatomy of the ankle joint, when using the ankle dorsiflexion and the dynamic distraction technique, and to propose an arthroscopic examination system for the anterior ankle compartment. Methods: Ankle arthroscopy was performed in 20 fresh frozen specimens. Arthroscopic examination was performed with the arthroscope introduced through the anteromedial portal. The anterior compartment was examined in ankle dorsiflexion without distraction. The compartment was examined in four steps: (1) lateral area including the lateral gutter; (2) the central area of the anterior tibial rim; (3) the medial area including the medial gutter; (4) the talar neck. Next, distraction was applied to visualise the anterior compartment again and to examine the central and posterior ankle compartments. Results: Anatomic intra-articular structures were visualised in all specimens. Four intra-articular fat pads, one anteromedial, two syndesmotic and another posteromedial, were constantly observed. A description of the normal arthroscopic anatomy of the ankle using the ankle dorsiflexion and the dynamic distraction technique is detailed for the anterior, central and posterior compartments. Conclusion: The ankle arthroscopic procedure without distraction allows constant visualisation of the ATFL’s superior fascicle on the floor of the lateral gutter, the ATiFL’s distal fascicle laterally and the most anterior margin of the deltoid ligament in the medial gutter (anterior tibiotalar ligament). However, ankle distraction is required to observe the central and posterior compartments, but it does not provide optimal visualisation of the anterior ankle compartment structures. Level of evidence: V.

Background Access to the talar dome for the treatment of osteochondral lesions (OCLs) can be achieved via several different approaches to the ankle joint. The recent description of an anatomical nine-grid scheme of the talus has proven useful to localise OCLs but no studies have demonstrated which approaches are indicated to access each of these zones. The aim of this study is to demonstrate the access afforded to each zone by each approach. Methods Four standard soft tissue ankle approaches were performed simultaneously in ten fresh-frozen cadavers (anterolateral — AL, anteromedial — AM, posterolateral — PL, posteromedial — PM). The area of the talus, which was accessible with an instrument perpendicular to the surface was documented for each of the approaches. Using ImageJ software the surface area exposed with each approach was calculated. The talar dome was then divided using a nine-grid scheme and exposure to each zone was documented. Results The AL, AM, PL and PM approaches allow for exposure of 24%, 25%, 5%, 7% of the talar dome respectively. The AL gives access to zones 3 (completely) and 2, 5, 6 (partially); the AM to zones 1 (completely) and 2, 4, 5 (partially); the PL to zones 9 and 8 (partially); and the PM to zones 7 and 8 (partially). Conclusions A large area of the talar dome cannot be easily accessed with the use of standard soft tissue approaches (39%). Minimal or no access is achieved for grid zones 4–6 and 8. In those instances careful preoperative planning is necessary and extended exposure can be achieved with the use of osteotomies, section of the ATFL or through modified approaches.

The Kager fat pad is one of the largest soft tissue structures local to the ankle joint, yet it is poorly understood. It has been hypothesised to have a role in Achilles tendinopathy. This study aimed to investigate the pressure areas in the Kager fat pad adjacent to the Achilles tendon and to assess the anatomy and deformation of the Kager fat pad in cadavers. Twelve fresh frozen cadaveric ankles (mean age 44 years, range 38–51) were mounted in a customized testing rig, enabling plantar flexion and dorsiflexion of the ankle, with the Achilles tendon loaded. A needle tipped pressure sensor was inserted in two areas of the Kager fat pad under ultrasound guidance (retrocalcaneal bursa and at 3 cm proximal from Achilles insertion). Pressure readings were recorded at different flexion angles. Following testing, the specimens were dissected to expose the Kager fat pad and retrieve it for analysis. MRI images were also taken from three healthy volunteers and the Kager fat pad deformation examined. Mean pressures significantly increased in all specimens at terminal ankle plantar and dorsi flexion in both regions (p

Neurovascular structures around the ankle are at risk of injury during arthroscopic all-inside lateral collateral ligament repair for the treatment of chronic ankle instability. This study aimed to evaluate the risk of damage to anatomical structures and reproducibility of the technique amongst surgeons with different levels of expertise in the arthroscopic all-inside ligament repair. Twelve fresh-frozen ankle specimens were used for the study. Two foot and ankle surgeons with different level of experience in the technique performed the procedure on 6 specimens each. The repair was performed following a standardized procedure as originally described. Then, an experienced anatomist dissected all the specimens to evaluate the outcome of the ligament repair, any injuries to anatomical structures and the distance between arthroscopic portals and the superficial peroneal nerve (SPN) and sural nerve. Dissections revealed no injury to the nerves assessed. Mean distance from the anterolateral portal and the SPN was of 4.8 (range 0.0–10.4) mm. The mean distance from the accessory anterolateral portal to the SPN and sural nerve was of 14.2 (range 7.1–32.9) mm and 28.1 (range 2.8–39.6) mm, respectively. The difference between the 2 surgeons’ groups was non-statistically significant for any measurement (mm). In all specimens both fascicles of the anterior talofibular ligament were reattached onto its original fibular footprint. The calcaneofibular ligament was not penetrated in any specimen. The all-inside arthroscopic lateral collateral ligament repair is a safe and reproducible technique. The clinical relevance of this study is that this technique provides a safe and anatomic reattachment of the anterior talofibular ligament, with minimal risk of injury to surrounding anatomical structures regardless of the level of experience with the technique.

Ankle arthroscopy has significantly evolved, and nowadays it is a common procedure treating ankle instability as secondary intra-articular pathology, and ligament injury can be addressed through the same portals.

The extensor retinaculum is a reinforcement of the anterior crural fascia. Usually includes the superior extensor retinaculum and inferior extensor retinaculum which are both in continuity with the anterior fascia of the leg. Herein, there will be presented details of anatomy and clinical implications of these structures in the topic of lateral ankle instability.

Microinstability is an emerging concept among the possible causes of ankle symptoms and disability. Injury to the superior fascicle of the anterior talofibular ligament might play a key role in this condition. Microinstability of the ankle is considered as a low degree of mechanical lateral ankle instability. A mismatch between symptoms and imaging is very frequent once current imaging options lack sensitivity to identify this pathology which can latterly be confirmed arthroscopically. Moreover, there are also no reproducible objective findings on clinical examination which also contributes to its poor characterization.

Arthroscopic techniques for the treatment of ankle instability are increasing. The possibility of treating concomitant ankle pathology and ankle instability in the same procedure with similar outcomes and minor complications is making foot and ankle surgeons rethink the role of the current gold standard technique, the open Brostrom-Gould procedure. The improvement of arthroscopic procedures in the ankle joint, as has happened before in other joints, is forcing the evolution of the classic open gold standard techniques toward an arthroscopic approach. A nondistraction and ankle dorsiflexion procedure is the key arthroscopic technique. The anterior talofibular ligament's superior fascicle, an intra-articular structure, is located on the floor of the lateral gutter, and distraction detrimentally narrows the view and access to this space.

ATFL’s superior fascicle injury has been considered to be the underlying cause in cases of ankle microinstability. As its clinical diagnosis can be difficult, arthroscopic examination may be the only objective diagnostic tool. The purpose of this study was to determine what types of injuries to the ATFL’s superior fascicle are associated with ankle microinstability, and to provide the reader with an arthroscopic classification of the types of microinstability affecting the ankle. Ankle arthroscopy video records obtained during a four-year period from 232 patients with the diagnosis of ankle microinstability were reviewed. The characteristics of the ATFL’s superior fascicle injury were identified, described and recorded along with any concomitant intra-articular pathology. Four different injury patterns were consistently seen affecting the ATFL’s superior fascicle. These ranged from ligament attenuation associated with loss of tension (type I), through to partial detachment (type II) or total detachment (type III) from the fibula. Finally, a total or partial resorption of the ATFL’s superior fascicle (type IV) was also observed. There was a statistically significant association between the type of injury identified and the rate of intra-articular pathology observed arthroscopically. Equally, the higher the type in the classification, the higher the rate of loose bodies, lateral talar OCD, deltoid “open book” tears, and anterior soft-tissue formation. Different types of ATFL’s superior fascicle injury can be observed in patients with ankle microinstability, ranging from ligament attenuation associated with a loss of tension (8.2%) to different degrees of partial (69.1%) and total (16.8%) ligament detachment from the fibula, or ligament remnant resorption (5.9%). As the type of injury progresses along with the proposed classification, the rate of intra-articular injuries also increases. The clinical relevance of this study is that a morphological ATFL’s superior fascicle tear is recognized in patients with the diagnosis of ankle microinstability. IV.

A variety of operative approaches and methods of fixation have been described for ankle arthrodesis. Arthroscopic ankle arthrodesis (AAA) has demonstrated to be an effective option with high fusion rates and minimal complications. In comparison to open surgery, arthroscopic techniques demonstrated quicker time to union with equivalent or higher union rates and faster recovery. Shorter hospital stays and lower costs are also in favor of arthroscopic procedures. The aim of this chapter is to describe the surgical technique of anterior arthroscopic ankle fusion using screws, its indications, and limits.

The ankle is a highly congruent synovial, hinge-type joint, in which the talus fits perfectly into the mortise formed by the tibial plateau, and the tibial and fibular malleoli. This anatomical conformation allows movement through only one axis, the bimalleolar axis, through which dorsiflexion and plantarflexion movements are produced. Normal values of the range of motion are 13–33° for dorsiflexion and 23–56° for plantarflexion [1].

Purpose: To assess the effectiveness of cadaveric ankle arthroscopy courses in reducing iatrogenic injuries. Methods: A total of 60 novice surgeons enrolled in a basic cadaveric ankle arthroscopy course were divided into two groups. Group A (n = 32) was lectured on portal placement and use of the arthroscope, whereas group B (n = 28) was in addition lectured on specific portal-related complications. Following the performance of anterior ankle arthroscopy and hindfoot endoscopy, the specimens were dissected and carefully assessed for detection of any iatrogenic injuries. Results: The rate of injury to the superficial peroneal nerve (SPN) was reduced from 25 to 3.6%, in group A compared with B (p = 0.033). Injuries to the peroneus tertius or extensor digitorum longus, the flexor hallucis longus and the tibial nerve or the Achilles tendon were also reduced in group B. Overall, the number of uninjured specimens was 50% (n = 30) and higher in group B (57%) than group A (44%). Lesions to the plantaris tendon, the sural nerve or the posterior tibial artery were more common in group B, however, without reaching statistical significance. Overall, 25 (13.9%) anatomic structures were injured in anterior arthroscopy compared to 18 (5%) in hindfoot endoscopy, out of a potential total of 180 and 360, respectively (p = 0.001). Conclusion: Dedicated lectures on portal-related complications have proven useful in reducing the risk of injury to the SPN, the commonest iatrogenic injury encountered in ankle arthroscopy. Hindfoot endoscopy is significantly safer than anterior ankle arthroscopy in terms of injury to anatomical structures.

The subtalar joint is the main joint of the peritalar complex and is synonymous with the talocalcaneal joint, where the plantar part of the talus articulates with the dorsal part of the calcaneus. The subtalar joint can be divided into a posterior joint and an anterior complex, the latter composed of the anterior talocalcaneal joint (anterior subtalar joint), middle talocalcaneal joint, and talonavicular joint (Fig. 2.1).

Ankle lateral collateral ligament complex has been the focus of multiple studies. However, there are no specific descriptions of how these ligaments are connected to each other as part of the same complex. The aim of this study was to describe in detail the components of the lateral collateral ligament complex—ATFL and CFL—and determine its anatomical relationships. An anatomical study was performed in 32 fresh-frozen below-the-knee ankle specimens. A plane-per-plane anatomical dissection was performed. Overdissecting the area just distal to the inferior ATFL fascicle was avoided to not alter the original morphology of the ligaments and the connecting fibers between them. The characteristics of the ATFL and CFL, as well as any connecting fibers between them were recorded. Measures were obtained in plantar and dorsal flexion, and by two different observers. The ATFL was observed as a two-fascicle ligament in all the specimens. The superior ATFL fascicle was observed intra-articular in the ankle, in contrast to the inferior fascicle. The mean distance measured between superior ATFL fascicle insertions increases in plantar flexion (median 19.2 mm in plantar flexion, and 12.6 mm in dorsal flexion, p

The aim of this study was to systematically evaluate the available literature on minimally invasive surgical (MIS) treatment for hallux valgus and to provide an overview of the different surgical techniques. A systematic review of the literature available in MEDLINE, EMBASE, and the Cochrane database was performed including studies from January 2001 to 1 January 2018. The radiological outcomes (hallux valgus angle (HVA), intermetatarsal angle (IMA)), complication rates, and clinical outcome scores were evaluated. The MINORS scale was used to assess the methodological quality of included articles. Of 278 reviewed articles, 23 met the inclusion criteria. The included studies reported on the results of 2279 procedures in 1762 patients. The surgical techniques were divided into five categories: the Bosch technique, MIS Chevron-Akin, Reverdin-Isham procedure, Endolog system, and techniques involving distal soft tissue release and fixation. Results regarding radiological correction, clinical outcomes, and complication rate varied widely. The studies included were of too little level of evidence to allow for data pooling or meta-analysis. There were too few studies on each surgical technique category to assess whether one is more effective than the rest. However, there is some evidence that the Chevron and Akin showed the most potential for improvement of the HVA and the Endolog for the IMA. An overall complication rate of 13% was obtained among all included studies. Appropriately powered randomized controlled trials, utilizing validated outcome measures, blinded assessors, and long-term follow up are needed to assess the efficacy of MIS techniques.

An increasing role of arthroscopy as the definitive treatment for ankle instability has been reported, and assisted or all-arthroscopic techniques have been developed. However, treatment of chronic ankle instability with poor remnant ligament-tissue quality is still challenging. The aim of this study was to describe the technique and report the results of the arthroscopic ATFL all-inside repair with suture augmentation to treat patients with poor remnant ligament-tissue quality. Fifteen patients [9 men and 6 women, median age 30 (19–47) years] with chronic ankle instability and poor remnant ligament-tissue quality were treated by arthroscopic means after failing non-operative management. Median follow-up was 18 (12–23) months. Through an arthroscopic all-inside technique, and using a suture passer and two knotless anchors, the ligament was repaired. Then, the anchor’s residual suture limbs were not cut, but were recycled and used for augmentation of the ligament repair. Arthroscopic examination demonstrated an isolated anterior talofibular ligament (ATFL) injury with poor remnant ligament tissue in the 15 patients. All patients reported subjective improvement in their ankle instability after the arthroscopic all-inside ligaments repair and suture augmentation. The median AOFAS score increased from 66 (44–87) preoperatively to 100 (85–100) at the final follow-up. Chronic ankle instability with poor remnant ligament-tissue quality can be successfully treated by an arthroscopic all-inside repair and suture augmentation of the ligament. The clinical relevance of the study is the description of the first arthroscopic all-inside anatomic ATFL repair with suture augmentation that offers the benefit of maintaining the native ligament while reinforcing the repair, especially in patients with poor remnant ligament-tissue quality. IV, retrospective case series

Background: Haglund syndrome is a common cause of heel pain. Risk for tendon detachment after calcaneoplasty can exist. Open Achilles tendon detachment, calcaneoplasty, bursectomy, pathologic tendon-tissue debridement, and tendon reattachment of the Achilles tendon is a common surgical management of Haglund syndrome combined with insertional Achilles tendinopathy. The aim of this study was to describe the endoscopic calcaneoplasty and anchor suture augmentation of the Achilles insertional area, and the results obtained in patients with an increased risk of Achilles tendon rupture after calcaneoplasty. Methods: Between 2012 and 2015, endoscopic calcaneal ostectomy and suture anchor augmentation was performed in 12 patients. Mean age was 44.8 years (range, 35-52 years), and mean follow-up was of 33.5 months (range, 21-46 months). Results: The mean AOFAS score increased from 70 preoperatively (range, 55-85) to 92 (range, 63-100) at final follow-up. The mean VISA-A questionnaire increased from 34 preoperatively (range, 15-63) to 92 (range, 30-100) at follow-up. No major complications were reported. All patients returned to their daily activities without limitations, but 2 described complaints with sports activity. Conclusion: Endoscopic calcaneoplasty and tendon augmentation with suture anchor for the treatment of Haglund syndrome was a reproducible and safe technique that offered the advantages of the endoscopic technique. Level of Evidence: Level IV, retrospective case series.

Background: Minimally invasive (MI) surgery is becoming increasingly popular in the treatment of hallux valgus (HV). The scarf osteotomy is an effective procedure with a track record in open HV surgery. We adapted this effective osteotomy to MI surgery as a novel technique never reported before. The aim of this study was to compare the clinical and radiologic outcomes of patients who underwent open or MI scarf. Methods: Between 2017 and 2018, 58 patients were randomized to either open or MI scarf to treat HV deformity. Prospective patient-reported outcome measures and weightbearing radiographs were obtained. Data included the AOFAS score, radiologic angular correction, operative time, fluoroscopy radiation dose, and postoperative pain on visual analog scale (VAS). Results: The mean follow-up was of 21 (range, 12-38) months. Radiologic measurements (postoperative hallux valgus angle, first-to-second intermetatarsal angle, and distal metaphyseal articular angle) were similar in both groups and showed statistically significant improvement from preoperative measures. The mean operative time for the MI group was 16.7 vs 26.1 minutes in the open group, a statistically significant difference. Radiation exposure was 14 times higher in the MI group when compared to the open group (mean: 34 vs 2.4 mGy/cm2, P < .001). There were no major complications in either group. Conclusions: The MI scarf provides a clinically and radiologically equivalent outcome to open scarf for the treatment of HV with reduced operative time and immediate postoperative VAS for pain but is associated with a small increase in radiation exposure. Level of Evidence: Level I, randomized controlled trial.

The purpose of this study is to propose recommendations for the treatment of patients with chronic lateral ankle instability (CAI) based on expert opinions. A questionnaire was sent to 32 orthopaedic surgeons with clinical and scientific experience in the treatment of CAI. The questions were related to preoperative imaging, indications and timing of surgery, technical choices, and the influence of patient-related aspects. Thirty of the 32 invited surgeons (94%) responded. Consensus was found on several aspects of treatment. Preoperative MRI was routinely recommended. Surgery was considered in patients with functional ankle instability after 3–6 months of non-surgical treatment. Ligament repair is still the treatment of choice in patients with mechanical instability; however, in patients with generalized laxity or poor ligament quality, lateral ligament reconstruction (with grafting) of both the ATFL and CFL should be considered. Most surgeons request an MRI during the preoperative planning. There is a trend towards earlier surgical treatment (after failure of non-surgical treatment) in patients with mechanical ligament laxity (compared with functional instability) and in high-level athletes. This study proposes an assessment and a treatment algorithm that may be used as a recommendation in the treatment of patients with CAI. V.

Ankle dorsiflexion arthroscopic technique with distraction at a surgeon's discretion is the current standard for ankle arthroscopy in most parts of the world. Reasons favoring the use of dorsiflexion during anterior ankle arthroscopy are based on the insertion of the anterior ankle joint capsule, which happens at a distance from the articular surfaces: this allows a large and safe anterior working area during dorsiflexion; ankle dorsiflexion also reduces the tension of anterior neurovascular structures and moves them away from the anterior aspect of the ankle, which protects them from damage during performance of the arthroscopic procedure; in addition, a lower rate of complications has been reported when dorsiflexion without distraction is being used for ankle arthroscopy. Nevertheless, intermittent ankle distraction can still be used during ankle arthroscopic procedures, but with just a few indications. In this infographic, authors explore and present the current indications for distraction in ankle arthroscopy as well as the broader indications for performing ankle dorsiflexion arthroscopic technique.

Chronic ankle instability has been described as presenting with complete tears of both the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) in 20% of cases. Arthroscopic techniques to treat chronic ankle instability are increasingly being reported and in some instances they can be technically demanding. The aim of this study was to describe an arthroscopic all-inside repair of both the ATFL and CFL, and to report the outcomes of a group of patients with chronic ankle instability that underwent the technique. Twenty-four patients [22 male and 2 female, median age 41 (range 22–56) years] with chronic ankle instability and torn ATFL and CFL were treated arthroscopically after failing non-operative management. Median follow-up was 35 (mean 34.7, and range 18–55) months. Through an arthroscopic all-inside technique, and using a suture passer and two knotless anchors, both fascicles of the ATFL and the CFL were repaired. Arthroscopic examination demonstrated ATFL and CFL injuries in all patients. Subjective improvement in their ankle instability was observed postoperatively. The anterior drawer and the talar tilt tests were negative at follow-up. The median AOFAS score increased from 65 (mean 65, range 52–85) preoperatively to 97 (mean 97, range 85–100) at final follow-up. Chronic ankle instability with concomitant injury of both the ATFL and CFL, can be successfully treated by an arthroscopic all-inside repair. The clinical relevance of the study is the description of the first arthroscopic all-inside ATFL and CFL anatomic repair technique, which offers excellent clinical results and the inherent benefits from minimally invasive surgery. IV, retrospective case series.

Tendon grafts are often utilized for reconstruction of the lateral ligaments unamenable to primary repair. However, tendon and ligaments have different biological roles. The anterior tibiofibular ligament’s (ATiFL) distal fascicle may be resected without compromising the stability of the ankle joint. The aim of this study is to describe an all-arthroscopic and intra-articular surgical technique of ATiFL’s distal fascicle transfer for the treatment of chronic ankle instability. Five unpaired cadaver ankles underwent arthroscopic ATiFL’s distal fascicle transfer using a non-absorbable suture and a knotless anchor. Injured or absent ATiFL’s distal fascicle were excluded from the study. Following arthroscopy, the ankles were dissected and evaluated for entrapment of nearby adjacent anatomical structures. The ligament transfer was also assessed. The distance between the anterolateral (AL) portals and the superficial peroneal nerve (SPN) was measured and the shortest distance was reported. All specimens revealed successful transfer of the tibial origin of the ATiFL’s distal fascicle onto the talar insertion of anterior talofibular ligament’s (ATFL) superior fascicle. The fibular origin of the ATiFL’s distal fascicle remained intact. There were no specimens with SPN or extensor tendon entrapment. The median distance between the proximal AL portal and SPN was 3.8 mm. The median distance between the distal AL portal and SPN was 3.9 mm. An all-arthroscopic approach to an ATiFL’s distal fascicle transfer is a reliable method to reconstruct the ATFL’s superior fascicle. Transfer of ATiFL’s distal fascicle avoids the need for tendon harvest or allograft. The lack of injury to nearby adjacent structures suggests that it is a safe procedure. The clinical relevance of the study is that ATiFL’s distal fascicle can be arthroscopically transferred to be used as a biological reinforcement of the ATFL repair, or as an ATFL reconstruction.

The open “Brostrom-Gould” procedure has become the gold standard technique for the treatment of chronic ankle instability. Although arthroscopic techniques treating ankle instability have significantly evolved in the last years, no all arthroscopic Brostrom-Gould has been described. The aim of the study was to describe the all-arthroscopic Brostrom-Gould technique [anterior talofibular ligament (ATFL) repair with biological augmentation using the inferior extensor retinaculum (IER)], and to evaluate the clinical results in a group of patients. Fifty-five patients with isolated lateral ankle instability were arthroscopically treated. Arthroscopic ATFL repair with biological augmentation was performed through a two-step procedure. First, the ligament is reattached through an arthroscopic procedure. Next, the ligament is augmented with the IER that is endoscopically grasped. Both the ligament repair and its augmentation with IER were performed with the help of an automatic suture passer and two soft anchors. Characteristics of the patients, and pre- and postoperatively AOFAS and Karlsson scores were recorded. The median preoperative AOFAS score increased from 74 (range 48–84) to 90 (range 63–100). According to the Karlsson score, the median preoperative average increased from 65 (range 42–82) to 95 (range 65–100). No major complications were reported. Only one case (1.8%) required a revision surgery at 23 months of follow-up. The arthroscopic all-inside ATFL repair with biological augmentation using the IER is a reproducible technique. Excellent clinical results were obtained. The technique has the advantage of its minimally invasive approach and the potential to treat concomitant ankle intra-articular pathology. Retrospective case series, Level IV.

Foot and ankle arthroscopy continues to evolve, and a thorough knowledge of relevant anatomy is important to avoid complications. For this purpose, we have focused this chapter in the anatomy of the main arthroscopic areas in the foot and ankle: the joint, subtalar joint and first metatarsophalangeal joint.

With advancements in cutting-edge technologies, minimally invasive diagnostic and therapeutic techniques are continuing to evolve to approach this condyloid joint which is a frequent source of disease. Since Watanabe’s description in 1972 [1], although scarce, treatment of various pathologies such as pigmented villonodular synovitis [2–4], hallux rigidus [2, 5], hallux valgus [6–8], osteochondral lesions [2, 9, 10], sesamoiditis [11, 12], and gouty tophi [4, 13–15] has been reported in the past. The understanding of surgical approaches and available portals will allow surgeons to strategically address specific lesions while minimizing postoperative pain and complications.

Background:Operative management of chronic Achilles tendon ruptures is challenging, and numerous techniques have been described. Risk of infection and wound breakdown have been described after open techniques, and minimally invasive methods have been proposed to avoid them. The aim of this study was to describe the clinical and radiological results obtained after endoscopic flexor hallucis longus (FHL) tendon transfer in patients with chronic Achilles tendon rupture.Methods:Between 2012 and 2015, a total of 22 patients were endoscopically treated for chronic Achilles tendon rupture. Mean age was 69 years (range, 59-84 years). Mean follow-up was 30.5 months (range, 18-46 months). Preoperative magnetic resonance imaging (MRI) was obtained and tendon gap measured. An MRI was obtained at 9 to 12 months following surgery to evaluate Achilles tendon changes.Results:Preoperative MRI examination showed a mean tendon gap of 6.3 cm (range, 3-10.7 cm). The MRI control was obtained only in 12 patients, and a normal or close to normal Achilles tendon was observed in all but 1 patient. The mean American Orthopaedic Foot & Ankle Society score increased from 55 preoperatively (range, 26-75) to 91 (range, 74-100) at final follow-up. All patients returned to their daily activities without difficulties. No patients reported complaints or symptomatic deficits of great toe flexion strength. No major complications were encountered.Conclusion:Chronic Achilles tendon ruptures were successfully treated by an all-endoscopic procedure. The endoscopically assisted FHL transfer provided excellent results while benefiting from the minimally invasive procedure advantages. However, it entailed some technical challenges and may not be suitable for less experienced surgeons.Level of Evidence:Level IV, retrospective case series.

Background: Snapping peroneal tendons is a rare cause of lateral ankle pain. Two subgroups have been described: chronic subluxation with superior peroneal retinaculum (SPR) injury and intrasheath subluxation with SPR intact. The aim of the study was to report the tendoscopic findings and results in patients affected by snapping peroneal tendons without evident dislocation. Methods: Between 2010 and 2015, a total of 18 patients with a retromalleolar “click” sensation and no clinical signs of peroneal tendon dislocation underwent tendoscopy. Mean age was 29 years (range, 18-47). Mean follow-up was 45 months (range, 18-72). Results: Tendoscopic examination revealed an intact SPR in 12 patients. Of these 12, a space-occupying lesion was present in 7, a superficial tear of peroneus brevis in 4, and a shallow fibular groove in 7. An SPR injury without peroneal tendon dislocation was observed in the remaining 6 patients. All these 6 patients presented a shallow fibular groove. Although the SPR was injured, they had been diagnosed as intrasheath subluxation. Patients with intrasheath subluxation and intact SPR underwent debridement of a space-occupying lesion in 11 cases and fibular groove deepening in 5 cases. Patients with intrasheath subluxation and SPR injury underwent fibular groove deepening without addressing the SPR. At follow-up, the mean American Orthopaedic Foot & Ankle Society score increased from 76 (range, 69-85) preoperatively to 97 (range, 84-100). No recurrence or major complications were reported. Conclusion Intrasheath subluxation of peroneal tendons was successfully treated tendoscopically. A new subgroup of intrasheath subluxation with SPR injury but no clinically evident peroneal tendon dislocation is reported. Level of Evidence: Level IV, case series.

The growing popularity of minimally invasive surgical (MIS) procedures makes it necessary that new anatomical references arise, to aid in tridimensional orientation and localization of structures that are not directly visible to the surgeon. This is especially critical for structures at risk like nerves or blood vessels. Optimization of the handling of cadaveric material and the combination of multiple techniques compensate for the limited availability of adequate specimens. The described protocol combines anatomical plane-by-plane dissection and sectional anatomy of fresh-frozen specimens to help localize relevant structures, such as nerves, arteries, veins and to correctly position the portals during MIS procedures. Depiction of these structures in anatomy textbooks can differ from what is encountered in the surgical field; and for this reason, new anatomical studies with a surgical orientation are needed. However, this is a complex, time-consuming technique requiring specific training. The anatomical references described with the so-called 'clock method' provide the surgeon with an easy and reproducible system to locate the path of the nerves at risk in Hallux Valgus MIS procedures. This model can be extrapolated to many other minimally invasive surgical procedures.

Background The purpose of this study is to describe a simple and reproducible method to localize the neurological structures at risk and to describe a safe zone for hallux minimally invasive surgery (MIS) procedures. Methods Ten fresh-frozen cadaveric feet were dissected to identify the dorsomedial digital nerve (DMDN) and the dorsolateral digital nerve (DLDN) of the first toe. Axial sections were performed at the sites of metatarsal osteotomies. We documented the position of the nerves with respect to the extensor hallucis longus (EHL) tendon using a clock method superimposed on the axial section Results The DMDN was found at an average of 26.2° medial to the medial border of the EHL tendon. (SD 11.26, range 14.5–45.5), whereas the average distance of the DLDN was 32.3° lateral to the medial border of the EHL tendon. (SD 6.29, range 13.5–40). Conclusions Using the clock method the DMDN and DLDN were found consistently between 10 o'clock and 2 o'clock in either right and left feet. The clock method may facilitate avoiding the area where these nerves are located serving as a valuable tool in minimally invasive foot surgery.

Introduction Operative correction of symptomatic bunionette by means of minimally invasive (MI) osteotomies of the 5th metatarsal (M5) has gained popularity. This study aims to investigate the safe zones of commonly used techniques and the risk of injury to neurological structures. Materials and methods Ten human fresh frozen cadaveric feet were dissected and branches of the sural nerve were identified. A frontal section of the feet was performed at the site of the skin incision described for M5 MI osteotomies (corresponding to distal and mid diaphyseal osteotomies). The location of the lateral dorsal cutaneous nerve (LDCN) of the sural nerve or its branches was documented using a goniometer and o’clock references placed on the frontal section of the M5. Results The LDCN showed variations in the distribution of its branches, forming the dorsolateral branch – a single terminal branch for the 5th toe – in 6/10 cases or two terminal branches – the dorsolateral and dorsomedial – in 4/10. At the point of osteotomies, the dorsolateral branch was identified at a mean of 22.7° from the extensor tendon around the M5 circumference and in all cases between 12 and 2 o’clock in a right foot or 10 o’clock to 12 o’clock in a left. Conclusion The studied M5 osteotomies can place the dorsolateral branch of the fifth toe at risk and safe zones lie between 10 o’clock to 2 o’clock in any foot laterality. If these landmarks are considered, the risk of nerve damage is minimized when performing MI osteotomies of the M5.

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.

Acute injuries of the ankle are one of the most common injuries seen by general practitioners and emergency departments [1]. They involve approximately 25% of all injuries of the musculoskeletal system. Inversion trauma, also referred to as lateral ankle sprains, constitutes a large proportion of these injuries [2-4].

Full thickness rotator cuff tears are a common cause of shoulder pain and disability. While the role of the rotator cuff seems to be well known, the clinical significance of the biceps tendon for shoulder function has still been a subject of controversy. The aim of this study was to evaluate differences between tenodesis or tenotomy in simultaneous rotator cuff repair. For this retrospective study 53 consecutive patients (25f/28m, O age 58 years) undergoing arthroscopic double row rotator cuff reconstruction and suture bridge repair were included. The LHB was treated with tenodesis (n = 24) or tenotomy (n = 29). Clinical examination was carried out for all patients after an average of 34 months (range 27–38) following arthroscopic surgery. The Constant score, level of pain, range of motion in flexion and abduction, and isometric force for the operated and healthy shoulder in flexion and abduction were recorded. Patients in the tenodesis and tenotomy group reached similar good result regarding the Constant score (86.6 ± 11.9 vs. 81.3 ± 12.2; P = 0.120), pain (median 0, range 0–8 vs. Median 0, range 0–10; P = 0.421), and range of motion (flexion: median 180°, range 90°–180° vs. median 180°, range 90°–180°; P = 0.833; abduction: median 180°, range 90°–180° vs. median 180°, range 120°–180°; P = 0.472). Postoperative popeye sign was found only in one patient (1.9 %). At the time of postoperative follow-up, no patient reported cramping of the biceps. Isometric forces in abduction of the tenotomy group (mean 4.7 ± 2.9 kg; maximum 5.5 ± 2.8 kg) was significant lower compared to the tenodesis group (mean 6.6 ± 3.0 kg, P = 0.019; maximum 7.7 ± 2.9 kg, P = 0.007) and compared to healthy shoulders (mean 6.1 ± 3.0 kg P = 0.004; maximum 7.4 ± 3.1 kg, P = 0.001), all other measurements were similar. According to our results arthroscopic biceps tenodesis and tenotomy are valuable procedures in simultaneous rotator cuff repair regarding function, pain, and range of motion. However, the tenotomy group showed reduced strength in abduction. Level IV, retrospective case series.

Endoscopy for the posterior region of the ankle through two portals is becoming more widespread for the treatment of a large number of conditions which used to be treated with open surgery years ago. The tendon of theflexor hallucis longus(FHL) travels along an osteofibrous tunnel between the posterolateral and posteromedial tubercles of the talus. Chronic inflammation of this tendon may lead to painful stenosing tenosynovitis. The aim of this report is to describe two cases depicting an accessory tendon which is an anatomical variation of theflexor hallucis longusin patients with posterior friction syndrome due to posterior ankle impingement and associated with a posteromedial osteochondral lesion of the talus. The anatomical variation (FDAL) described was a finding during an endoscopy of the posterior region of the ankle, and we have spared it by sectioning the superior flexor retinaculum only. The accessory flexor digitorum longus is an anatomical variation and should be taken into account when performing an arthroscopy of the posterior region of the ankle. We recommend this treatment on this type of injury although we admit this does not make a definite conclusion.

Gastrocnemius contracture has recently gained relevance owing to its suggested relationship with foot disorders such as metatarsalgia, plantar fasciopathy, hallux valgus, and others. Consequently this has induced a renewed interest in surgical lengthening techniques, including proximal gastrocnemius release, to resolve gastrocnemius contracture in patients with foot disorders. This article describes and discusses the general anatomy of the triceps surae and the surgical anatomy of the gastrocnemius.