Intermittent flexor hallucis longus dislocation: ultrasound findings

We report a case of intermittent dislocation of the flexor hallucis longus at its passage in the retro-malleolar area, related to a post-traumatic detachment of the retrotalar pulley from the medial tubercle of the talus. High-resolution ultrasound depicted the anterior dislocation of the tendon during dynamic stress, by asking the patient to flex his hallux against the examiner resistance, with the ankle in slight dorsiflexion. The tendon normally relocated after the dynamic maneuver. Tendon dislocation was associated with a painful snap.

Pigmented villonodular synovitis of the flexor hallucis longus tendon: A rare cause of leg pain in a 12-year-old girl

Pigmented villonodular synovitis is an uncommon benign neoplastic proliferation associated with the synovium, bursa, or tendon sheaths; most commonly occurring in the third to fourth decade of life. It is rare in children and may be painful or painless. Magnetic resonance imaging is the diagnostic study of choice. In this report, the radiologic, ultrasound, and magnetic resonance imaging findings of pigmented villonodular synovitis of the flexor hallucis longus in a 12-year-old girl are discussed. We briefly review the surgical findings as well. To our knowledge, this is the first case report that simultaneously synthesizes the imaging findings of 3 diagnostic imaging modalities for optimal visualization and is the youngest reported case of pigmented villonodular synovitis of the flexor hallucis longus tendon.

Flexor hallucis longus tendon morphology in dancers clinically diagnosed with tendinopathy

PURPOSE

The unique demands of dance technique make dancers more prone to certain pathologies especially of the foot and ankle. Flexor hallucis longus (FHL) tendinopathy, colloquially known as "dancer's tendinopathy," is common in dancers and not well studied. The purpose of this study was to assess if morphological alterations in tendon structure occur as an adaptive response to dance activity by comparing the FHL tendon in dancers to non-dancers, and if pathology further alters tendon morphology in dancers clinically diagnosed with tendinopathy.

METHODS

Three groups of ten participants were recruited (healthy non-dancers, healthy dancers, and dancers with FHL tendinopathy). Ultrasound images of the FHL tendons were analyzed for macromorphology by measuring the tendon thickness. The micromorphology was analyzed by determining the peak spatial frequency radius of the tendon. Our study did find increased tendon proper and composite tendon thickness in dancers with tendinopathy but no difference between asymptomatic dancers and non-dancers.

RESULTS

There was no significant difference in micromorphology found between any of the groups. As expected, dancers with tendinopathy demonstrated increased composite tendon and tendon proper thickness however, there was no evidence of adaptive thickening of the FHL tendon as might be expected for the dance population. There was also no evidence of micromorphological changes in the presence of clinically diagnosed FHL tendinopathy.

CONCLUSION

Because of the limited normative data for this pathology, these results can help improve diagnosis and therefore treatment for dancers to decrease the impact of this injury on their careers.

Endoscopic flexor hallucis longus tendon transfer with horizontal calcaneal fixation and suturing onto itself

Endoscopic flexor hallucis longus (FHL) tendon transfer to replace the calcaneal tendon is being increasingly performed. The main advantage is minimisation of approach-related morbidity. Fixation of the FHL tendon is usually achieved with a tenodesis screw placed in a vertical calcaneal tunnel. Here, we describe an endoscopic technique with FHL fixation by tenodesis in a horizontal calcaneal tunnel combined with suturing of the tendon onto itself. LEVEL OF EVIDENCE: IV.

Surgical treatment of chronic achilles tendon rupture: An anatomical consideration of various autograft options

Background

Acute Achilles tendon rupture is a common injury and when missed leads to the development of a chronic Achilles tendon rupture. Studies suggest surgical treatment (either repair or reconstruction) for most patients with a chronic Achilles rupture due to the functional deficit caused by the lack of an intact Achilles tendon. Numerous autograft options such as the flexor hallucis longus, hamstrings, peroneal and quadriceps tendon have been used to reconstruct the Achilles tendon, either as a tendon transfer or as an interposition graft. The choice of autograft used usually depends on the size of the defect left after debridement of the Achilles tendon edges, but is often dictated by surgeon preference and tissue availability. Currently, there is no consensus as to the best autograft option.

Aims and methodology

The aim of this study was to evaluate the various autograft options used to reconstruct the Achilles tendon, and the advantages and disadvantages of using each tendon, focussing specifically on the harvesting technique, anatomical and biomechanical properties. This was done by reviewing the current published literature, supplemented by carrying out anatomical dissection in the cadaveric lab.

Results

The flexor hallucis longus is synergistically related to the Achilles tendon and biomechanically strong, however harvesting can result in weakness in big toe flexion. The peroneus brevis whilst being biomechanically strong is a much shorter tendon compared to the other autograft options. Similarly, the quadriceps tendon is also a strong tendon option, but may not be appropriate for larger chronic Achilles tendon rupture gaps. The semitendinosus tendon can be tripled/quadrupled to resemble the Achilles tendon, but is associated with higher risks of patient morbidity when harvesting the tendon.

Conclusion

Treatment of chronic Achilles tendon ruptures remains a challenge. Each autograft option has its own unique advantages and disadvantages which should be considered on a case-specific basis. Further work is required to analyse the biomechanical properties of the autograft options to determine if one option is superior.

Evaluation of arthrokinematics and posterior soft tissues of the ankle during ankle dorsiflexion using ultrasound

BACKGROUND

Arthrokinematics (caudal and posterior movements of the talus) and posterior soft tissues of the ankle during ankle dorsiflexion have not been objectively evaluated in detail. This study aimed to investigate the characteristics of arthrokinematics and posterior soft tissues of the ankle during ankle dorsiflexion using ultrasound.

METHODS

Thirteen healthy adults participated in the study. Participants whose passive dorsiflexion range of motion (ROM) of the ankle joint was <35° were classified as the restricted group (n = 6), and participants whose passive ankle dorsiflexion ROM was ≥35° were classified as the control group (n = 7). Passive ankle dorsiflexion was performed to measure the ankle arthrokinematics. Strain elastography was performed to measure the elasticity of the flexor hallucis longus (FHL) and Kager's fat pad (KFP) at each dorsiflexion angle.

RESULTS

A significant difference in the posterior movement of the talus at the ankle dorsiflexion of 30° was observed between the two groups (P = 0.04). The elasticity of the restricted group was increased at all angles in both FHL and KFP (P < 0.05).

CONCLUSION

This study showed that it is possible to objectively evaluate the direction of ankle arthrokinematics and posterior ankle soft-tissue restrictions using ultrasound.

Navicular Tuberosity: A Surface Landmark for the Masterknot of Henry

Background

Medial aspect of foot is unexplored due to its complex anatomy. Masterknot of Henry is an important landmark in this region, which plays a key role during tendon transfer procedures especially in those involving the flexor hallucis longus and flexor digitorum longus. We aim to determine the exact anatomical location of masterknot of Henry with respect to the bony prominences of the medial aspect of the foot and compare these measurements to the length of the foot.

Methods

Twenty cadaveric below-knee specimens were dissected. Structures on the medial side of the foot were exposed. Distance of the masterknot of Henry from surrounding bony landmarks was measured. Depth of the masterknot from skin of the plantar aspect was also measured. Means of all parameters were calculated. Relation between measurements and the foot length was determined using correlation and regression analysis. P value of less than 0.05 was considered significant.

Results

Distance of masterknot of Henry from navicular tuberosity was found to be fairly constant of 19.965 mm. Foot length was found to be correlating with the distance between masterknot of Henry and medial malleolus, navicular tuberosity and its depth from the skin.

Conclusions

Navicular tuberosity can be considered an important surface landmark for the location of masterknot of Henry. Correlation of length of the feet with various measurements helps to find the masterknot considering the foot length to be an important variable. Good knowledge of surface anatomy leads to shorter operating time and less morbidity during procedures involving the flexor hallucis longus and flexor digitorum longus.

Posterior Ankle Impingement

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

Evaluation of Flexor hallucis tendon transfer in chronic insertional Achilles tendinopathy in over 50-year-old population using validated ankle scores

PURPOSE

Chronic insertional Achilles tendinopathy is a common pathology in the over 50 years old population. Patients not relieved with conservative treatment had to undergo surgical intervention for the management. This study evaluates the clinical outcome of FHL transfer in such patients using validated ankle functional scores.

METHOD

It is a retrospective study including 20 patients of either gender managed with debridement of the distal degenerative remnant Achilles tendon fibers either at the insertion site or the distal end of the torn tendon, resection of Haglund deformity with FHL transfer, and reattachment of Achilles tendon. The average age of the patients was 56.55 + 11 years (50-77 years) followed by over 35.6 months (Range 22-48months). The preoperative FAAM, FADI, SF 36, VAS, and AOFAS scores were calculated and followed every 6 months. The plantarflexion and dorsiflexion of the ankle were also recorded preoperatively and at follow-up visits.

RESULTS

All the patients were operated on by a single surgeon (MS) with the same surgical technique, implant, and rehabilitation protocol. All the patients were followed for an average of 35.6 months (Range 22-48 months). All the ankle scores, FAAM, FADI, SF36, VAS, and AOFAS improved in follow-ups. The mean plantarflexion and dorsiflexion were 39.30⁰+ 4.9⁰ and 12.5⁰+ 4.7⁰ respectively. Three patients had minor wound complications. All the patients returned to activities of daily living.

CONCLUSION

FHL transfer in elderly patients with insertional Achilles tendinopathy improves the validated ankle functional scores and decreases pain significantly. Furthermore, randomized studies with a larger study population and longer follow-ups may ascertain the beneficial effects.

Positional and dimensional relation of tendons around the first metatarsal bone with hallux valgus

PURPOSE

It was aimed to reveal whether the positions and dimensions of the extrinsic and intrinsic muscle tendons related to the hallux around the first metatarsal bone are affected by the severity of hallux valgus (HV) and whether tendon positional changes and tendon sizes affect each other.

METHODS

In formalin-fixed 46 feet, three HV angle subgroups (normal, mild, and moderate/severe) were defined. Width, thickness, and cross-sectional area (CSA) of tendons of the extensor hallucis longus (EHL) and brevis (EHB), abductor hallucis (AH), and flexor hallucis longus (FHL) were measured. On the clock model created in coronal plane, positional variations of each tendon were determined.

RESULTS

In the moderate/severe HV group, thickness and CSA of the EHB, width and CSA of the AH were smaller, compared to mild HV. Width and CSA of the FHL were smaller in moderate/severe HV than in the normal. Regardless of HV, the width and CSA of the FHL were greater in cases where the FHL was located more lateral, and the width of both FHL and AT were greater in cases where AH located was more plantar.

CONCLUSION

The smaller tendon size of two intrinsic (one plantar and one dorsal) and one extrinsic muscle in the moderate/severe HV group indicates that changes in the tendons are evident in cases of high severity of HV but not in cases of mild HV. Accordingly, the changes do not appear to be due to a factor limited to only one aspect of the foot. It is recommended to consider the possible biomechanical effects of AH, FHL, and EHB tendon dimensional weakness in surgical planning in moderate/severe HV cases.

Dynamic medial column stabilization using flexor hallucis longus tendon transfer in the surgical reconstruction of flatfoot deformity in adults

BACKGROUND

A common challenge in flatfoot reconstruction arises when there are multiple locations of collapse within the medial column. An extension of arthrodesis may lead to complications such as stiffness or adjacent joint arthritis. The purpose of this study was to report outcomes of flatfoot reconstruction using the dynamic medial column stabilization (DMCS) technique, which transfers the flexor hallucis longus (FHL) tendon to the first metatarsal base to support the entire medial column.

METHODS

We retrospectively reviewed 14 consecutive patients (14 feet) who underwent DMCS as an adjunct to flatfoot reconstruction. In all cases, a medial displacement calcaneal osteotomy and gastrocnemius recession were performed to address hindfoot valgus deformity and heel cord tightness, respectively. Deformity correction was assessed using preoperative and postoperative weightbearing radiographs. The newly defined metatarsal-cuneiform articular angle (MCAA) and naviculo-cuneiform articular angle (NCAA) were measured to assess correction at each medial column joints. Clinical outcomes included the FFI and VAS scores. Any complications related to the surgery were investigated.

RESULTS

All radiographic parameters significantly improved postoperatively. The sagittal plane correction occurred at all three joints within the medial column. Clinically, both FFI and VAS improved significantly at the final follow-up. One patient developed plantar pain under the first metatarsal head that may have been associated with the overtightening of the transferred tendon.

CONCLUSION

DMCS using FHL tendon transfer to the first metatarsal base was a useful technique for restoring the medial arch and correcting three planar deformities in the setting of flatfoot deformity.

Arnold Kirkpatrick Henry (1886-1962) and his eponym (Master Knot of Henry): a narrative review

PURPOSE

The aims of this review were to form a more precise description for Master Knot of Henry (MKH), and to modify classifications related to interconnections between flexor hallucis longus (FHL) and flexor digitorum longus (FDL) for showing all configurations in the literature.

METHODS

A literature search was performed in main databases to obtain information related to anatomical definitions and variations of MKH. The search was carried out using the following keywords: "Master Knot of Henry", "Chiasma plantare", "Flexor hallucis longus" and "Flexor digitorum longus". Information extracted from the studies was: sample size, numerical values, classifications, variation types, incidence of types, anatomical definitions of MKH, year of publication, and type of study.

RESULTS

This study proposes that MKH should be defined as the intersection territory where FDL crosses over FHL in the plantar foot. The postchiasmatic plantar area located at distal to MKH (the narrow space between MKH and the division of FDL) should be termed as the triangle of Henry. Moreover, the classification systems showing different configurations related to interconnections situated at Henry's triangle were updated as eight types to present all forms in the literature.

CONCLUSION

Our definitions may assist in determining the precise anatomical boundaries of MKH, and thus facilitate the use of MKH as a surgical landmark. In addition, our modified classification systems covering all variations in the current literature may be helpful for surgeons and anatomists to understand formations of the triangle of Henry, and the long flexor tendons of the lesser toes.

Increased flexor hallucis longus tension decreases ankle dorsiflexion

BACKGROUND

Restricted excursion of the flexor hallucis longus (FHL) is associated with several clinical problems. An FHL excursion measurement device (EMD) was used to objectively assess differences between patients with clinically normal or tight FHL tendons.

METHODS

188 patients (356 feet) were enrolled. The EMD measured maximum ankle dorsiflexion with the great toe in 15°, 30°, and 45° of dorsiflexion. All had clinical assessment of FHL tightness by their provider independently of the EMD measurement.

RESULTS

Increased hallux DF always caused decreased ankle DF. Patients with clinically tight FHLs demonstrated decreased ankle DF compared to normal subjects at all hallux positions (p<0.01). The EMD measurement was not sensitive enough for detection of FHL tightness in individuals. A clinically tight FHL was seen in almost 50% of feet.

CONCLUSIONS

Tension in the FHL can limit ankle DF. Clinical tightness of the FHL is likely more common than currently recognized.

Claw Toe: Anatomic Guide for Injection of Botulinum Toxin into Foot Muscles

BACKGROUND

Poor response to injection of botulinum toxin (BoNT) into the flexor digitorum longus (FDL) muscle has been reported especially in patients with claw foot deformity. We previously advocated BoNT injection into the flexor hallucis longus (FHL) muscle in such patients. Here, we determined the functional and anatomical relationships between FHL and FDL.

METHODS

Toe flexion pattern was observed during electrical stimulation of FHL and FDL muscles in 31 post-stroke patients with claw-foot deformity treated with BoNT. The FHL and FDL tendon arrangement was also studied in five limbs of three cadavers.

RESULTS

Electrical stimulation of the FHL muscle elicited big toe flexion in all 28 cases examined and second toe in 25, but the response was limited to the big toe in 3. FDL muscle stimulation in 29 patients elicited weak big toe flexion in 1 and flexion of four toes (2nd to 5th) in 16 patients. Cadaver studies showed division of the FHL tendon with branches fusing with the FDL tendon in all five limbs examined; none of the tendons was inserted only in the first toe. No branches of the FDL tendon merged with the FHL tendon.

CONCLUSION

Our results showed coupling of FHL and FDL tendons in most subjects. Movements of the second and third toes are controlled by both the FDL and FHL muscles. The findings highlight the need for BoNT injection in both the FDL and FHL muscles for the treatment of claw-toe deformity.

Effects of a "toes-off" modified heel raise on muscle coordination in non-dancers, dancers, and dancers with flexor hallucis longus tendinopathy

BACKGROUND

Tendinopathy of the flexor hallucis longus, commonly called "dancer's tendinitis", is a prevalent injury among female ballet dancers. Limited success of non-surgical interventions leads to many dancers undergoing tenolysis surgeries with risks and recovery times that can be detrimental to a dance career. The purpose of this study was to evaluate lower limb kinematics and muscle coordination during a modified traditional heel raise exercise where the toes hang off the edge of the support surface. We hypothesized this would decrease activation of the flexor hallucis longus and increase activation of larger plantarflexors.

METHODS

Healthy non-dancers (n = 11), healthy dancers (n = 10), and dancers with flexor hallucis longus tendinopathy (n = 9) performed traditional ("toes-on") and modified ("toes-off") heel raises with kinematic and electromyographic instrumentation of the lower leg.

FINDINGS

Participants maintained ankle excursion with the toes-off modification, while metatarsophalangeal joints had reduced excursion and greater excursion variability. Most healthy dancers (9/10) decreased flexor hallucis longus activation as predicted, but dancers with flexor hallucis longus tendinopathy showed a variable response with some decreasing activation (3/9) but others increasing activation up to 4-times. There were no changes in activation of other plantarflexors. Across groups, intrinsic foot muscle activation decreased with the toes-off modification.

INTERPRETATION

The toes-off modification decreased flexor hallucis longus activation in most of the healthy dancers but was insufficient to shift muscle coordination from the flexor hallucis longus to larger plantarflexors in dancers with flexor hallucis longus tendinopathy. Future work should investigate clinical cues or modifications to this "toes-off" heel raise intervention.

Ultrasonographic test for detecting the chiasma plantare formation between the flexor hallucis longus and flexor digitorum longus

PURPOSE

Flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendons are frequently used in surgery. Therefore, it is necessary to evaluate the chiasma plantare formation preoperatively. The development of ultrasonography (US) may help the chiasma plantare formation evaluation. The purpose of this study is to prove the usefulness of the US method using cadavers.

METHODS

Eleven cases (twenty-two ankles) were obtained from Asian adult cadavers. At first, we evaluated and compared the chiasma plantare formation using US. Later, we evaluated that using the findings after dissection as type A (connection from FHL to FDL of the second toe), type B (connection from FHL to the second and third toes), type C (connection from FHL to the second through fourth toes), or type D (connection from FHL to all lesser toes).

RESULTS

Chiasma plantare formation was classified as types A and B in fifteen and seven ankles, respectively. After dissection, chiasma plantare formation was classified as types A, B, and C in fourteen, six, and two ankles, respectively. Therefore, there was an 86% similarity between the two methods.

CONCLUSIONS

Chiasma plantare formation can be reliably and noninvasively evaluated using US. This may be useful for preoperative rehabilitation or surgical procedure planning.

A histological study on the tendons at chiasma plantare in pes cavus

INTRODUCTION

In the dysfunction of large muscles of the leg, tendon transfer surgery is found to be very helpful in restoring the normal function of these muscles. The tendons involved in the chiasma plantare play a major role in this regard.

OBJECTIVE

The present cadaveric study has been carried out in cadavers presenting pes cavus.

MATERIAL AND METHODS

Cadaveric feet presenting pes cavus were identified based on their foot prints. All these tendons and their interconnections were subjected to histological procedures. The sections of the tendons were stained with hematoxylin and eosin in order to identify the underlying pathologies in the tendons.

RESULTS

Various types of tendinous interconnections between the tendons of flexor digitorum longus and flexor hallucis longus were noted. The histological findings showed infiltration of lymphocytes in the tendon sheath indicating tenosynovitis and tendinitis. This could be attributed to the compression of the tendons. A few tendons were also stretched due to the skeletal framework of the foot in pes cavus. The bones along the medial longitudinal arch in pes cavus feet could tend to develop spurs or elongated tuberosity that could impinge on the tendons causing the tendons to stretch and elongate.

CONCLUSION

In harvesting the tendons for grafting, the surgeons must be aware about the pathologies involved, such as tendinitis or tenosynovitis, in order to reduce the time taken for the healing of the graft post-surgery. These variations and histological findings can sub-serve as an efficient guide for the restoration of non-functioning muscles of the lower limb.

Posterior Ankle Impingement and Flexor Hallucis Longus Pathology

Posterior ankle pain is a common complaint, and the potential causative pathologic processes are diverse. The constellation of these numerous etiologies has been collectively referred to as posterior ankle impingement syndrome. The pain associated with posterior ankle impingement is caused by bony or soft tissue impingement of the posterior ankle while in terminal plantar flexion. This condition is most frequently encountered in athletes who participate in sports that involve forceful, or repetitive, ankle plantar flexion. This article discusses the associated pathology, diagnosis, conservative treatment, and surgical techniques associated with flexor hallucis longus and posterior ankle impingement syndrome.

Flexor hallucis longus tendon branch test: Development and validation of a new method to assess anatomical variation of the tendinous slip

BACKGROUND

The flexor hallucis longus (FHL) muscle often has a tendinous slip with a variable number of branches. We aimed at developing the FHL branch test to determine the number of FHL branches.

METHODS

In anatomical validation study, 6 intact cadavers were used. The toe flexion angles were measured while the FHL and flexor digitorum longus (FDL) were manually pulled individually. For electrophysiological studies, 4 healthy men participated. The FHL was electrically stimulated, and electromyography (EMG) of the FHL and FDL were recorded during the FHL branch test.

RESULTS

The toe flexion angles' changes in the FHL pulling condition were equivalent with pulling FDL in toes with FHL branching. The electrical stimulation of the FHL produced similar flexion as the FHL branch test. EMG of the FHL was higher than FDL during the FHL branch test (p=0.036).

CONCLUSIONS

The FHL branch test could be used to evaluate the number of FHL branches.

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

BACKGROUND

It was hypnotized that presence and larger size of os trigonum (OT) can affect flexor hallucis longus tendon (FHL), so tenosynovitis, degeneration and partial tear can be developed.

METHODS

A total of 98 (Study group: 50, Control: 48) subjects included to study and compered status of FHL lesions. Sagittal length and axial width of OT were measured on MRI to determine effect of OT on FHL lesions and correlated with arthroscopic findings.

RESULTS

FHL tenosynovitis (p: 0,025), degeneration (p: 0,01) and partial tear (p: 0.008) was identified statistically high in study group. Statistical analysis revealed that as length of OT increased, frequency of degeneration (p: 0.03) and partial tear (p: 0.00) of FHL increased.

CONCLUSION

Analyzes were showed that the presence of os trigonum had an important role on the FHL pathologies. Additional finding of study was to demonstrate that possibility of FHL lesion increased as length of OT extended.

LEVELS OF EVIDENCE

Level 3.

Assessment of fibula flap with flexor hallucis longus's effect on head & neck tumor patients' quality of life and function of donor site

OBJECTIVE

Free fibular flaps (FFFs) have been widely used in mandibular reconstruction. It is still unclear whether retaining flexor hallucis longus (FHL) is needed for flaps. This study introduces a comparison in quality of life and donor-site function between those who have and haven't harvested FHL with FFF.

METHODS

Patients with FFFs were single-blind-randomly assigned into the FHL group or nFHL group. Patients were followed up preoperatively and 1, 3 and 6 months postoperatively via subjective evaluations (SF-36/AOFAS) and objective evaluation s(muscle strength and range of motion). Patients' hospitalization and intraoperative information, donor site morbidity were recorded.

RESULTS

Each group had 15 patients. The flap harvesting time in FHL group was shorter significantly than nFHL group (125.9 ± 24.8 min vs 146.7 ± 29.9 min, P = 0.048). There were no significant differences in hospitalization information such as operation time, hospitalization days and cost. Donor site morbidities at 1, 3 and 6 months postoperatively showed no significant differences except for the presence of claw toes (nFHL group > FHL group, 40% vs 0, P = 0.017; 53.3% vs 6.7%, P = 0.014; 60.0% vs 13.3%, P = 0.021). There were no significant differences in SF-36 and AOFAS scores. There were no significant differences in muscle strength and range of motion.

CONCLUSION

Excision of the FHL lowered the flap harvesting time. It did not increase donor site morbidity. The impacts on patients' quality of life and foot function were the same. The surgeons can use the FHL without considering the influence on patients if not retaining the FHL.

Communications between the tendons of flexor hallucis longus and flexor digitorum longus: a cadaveric study

INTRODUCTION

Tibialis posterior tendon insufficiency in adult acquired flat foot deformity (AAFFD) is treated by reinforcing the posterior tibial tendon (PTT) using grafts from flexor hallucis longus (FHL) and flexor digitorum longus (FDL). The communication between FHL and FDL will influence the length of the graft that can be harvested from FHL and FDL. In this study, we aim to study the patterns of communications between FHL and FDL tendons and the location of Master Knot of Henry (MKH) and point of division of FDL tendons in Indian population.

MATERIALS AND METHODS

In this observational descriptive study, 36 formalin-fixed cadavers were sourced from Subbaiah Institute of Medical Sciences, Shimoga, Karnataka, India, and JIPMER, Puducherry, India, during the period of 2017-19. Various parameters of the foot to locate the MKH and point of division of FDL tendons and various types of communications between FHL and FDL were observed.

RESULTS

Among the various types of communications between FHL and FDL tendons, type I was present in 61.76% of cases, type II in 2.94% of cases, type III in 7.35% of cases, type IV in 14.70% of cases, type V in 8.82% of cases, type VI in 0% of cases, type VII in 1.47% of cases and an unusual type in 2.94% of cases.

CONCLUSION

In the present study done in Indian population, we found that type I variety is present more commonly followed by type IV. FHL and FDL tendon grafts can be lengthened based on the communications between them. In type I variety, the communication can be severed at the FDL end to lengthen the tendon graft for harvest.

Checkrein Deformity of the Great toe Managed by Midfoot Flexor Hallucis Longus Z-Plasty: A Case Report

Introduction:

Checkrein deformities are rare and involve entrapment or fixed tethering of the flexor hallucis longus (FHL) tendon.

Case Report:

We present the case of a 25-year-old male who presented with complaint of clawing of his great toe. A history of previous open reduction internal fixation for distal tibia fracture was described 3 years back. Exploration of FHL tendons was performed at the level of the midfoot. Correction was achieved after z-plasty of FHL tendon. This case highlights another late complication of distal tibial fracture which should be actively looked for in patients with this injury. We describe the ease of surgical correction through an operative field free of scar tissue as compared to classical method of operating near fracture site and releasing adhesions of muscle belly.

Conclusion:

We suggest that exploration at the midfoot should be the primary surgical intervention in similar cases of checkrein deformity.

Endoscopic Management of Chronic Achilles Tendon Rupture

Chronic ruptures of the Achilles tendon are often missed injuries, which is challenging for the surgeon. The complications from reconstruction are a considerable concern. Primary repair may be attempted, but the missed injury often presents later than 4 weeks with gaps greater than 4 cm, necessitating more complex reconstructions using local tissues such as turn-down flaps and VY plasty, requiring large incisions in an unfavorable area of the body. We describe a step-by-step technique of endoscopic flexor hallucis longus reconstruction for chronic Achilles rupture, which decreases local complications. This article reviews the available literature for endoscopic flexor hallucis longus reconstruction.

Endoscopic Management of Chronic Achilles Tendon Rupture

Chronic ruptures of the Achilles tendon are often missed injuries, which is challenging for the surgeon. The complications from reconstruction are a considerable concern. Primary repair may be attempted, but the missed injury often presents later than 4 weeks with gaps greater than 4 cm, necessitating more complex reconstructions using local tissues such as turn-down flaps and VY plasty, requiring large incisions in an unfavorable area of the body. We describe a step-by-step technique of endoscopic flexor hallucis longus reconstruction for chronic Achilles rupture, which decreases local complications. This article reviews the available literature for endoscopic flexor hallucis longus reconstruction.

A semi-quantitative technique to assess excursion of the flexor hallucis longus

BACKGROUND

Recent research indicates that restriction in excursion of flexor hallucis longus (FHL) contributes to hallux rigidus development. As described in the literature, clinical evaluation of FHL excursion has poor interobserver reliability. A simple, inexpensive, easily used FHL relative excursion measurement device was developed and tested.

METHODS

64 subjects were enrolled with shoe size, height, weight, BMI, and age compared. Using a footplate and series of mechanical wedges, maximum ankle dorsiflexion was measured with the great toe in 15°, 30°, and 45° of dorsiflexion.

RESULTS

Ankle dorsiflexion decrease with progressive hallux dorsiflexion increase was statistically significant with a linear correlation (r²=.814 p<.001) and was not statistically related to shoe size, height, weight, BMI, or age.

CONCLUSIONS

This technique provides consistent assessment of the limitation to ankle dorsiflexion incurred by decreased FHL excursion, establishing groundwork for future studies to assess the relationship between diminished FHL excursion and FHL pathology.

[Reconstruction of neglected Achilles tendon rupture: flexor hallucis longus transfer versus gastrocnemius turn-down flaps]

Objective: To compare the outcome of either flexor hallucis longus transfer or turn-down of proximal Achilles tendon tissue repair in treating chronic Achilles tendon rupture. Methods: The clinical data of 21 patients who underwent repair of Myerson type Ⅲ chronic Achilles tendon rupture at Peking University Sports Medicine Research Institute from May 2012 to March 2015 were retrospectively analyzed. Among them, 11 cases were treated with flexor hallucis longus (FHL) transfer, and 10 cases were treated with gastrocnemius turn-down flaps repair. The American Orthopedic Foot & Ankle Society (AOFOS) hindfoot score and Tegner motor function score before and after surgery were recorded and compared between the two groups. Data comparison between groups was performed with t test. Results: The patients in the both group were followed up for an average of (21±7) months. The postoperative AOFOS hindfoot score in the long flexor and gastrocnemius groups were both significantly higher than those before surgery, and the differences were statistically significant (97.7±2.6 vs 72.0±8.1 and 96.0±5.5 vs 78.5±6.4, t=10.70, 6.42, both P<0.05).The postoperative Tegner scores of the two groups were also significantly higher than those before surgery (4.2±1.4 vs 0.7±0.4 and 4.1±0.8 vs 0.6±0.5,t=7.29, 9.35, both P<0.05). There were no significant differences in postoperative AOFOS hindfoot scores and Tegner motor function scores between the two groups (both P>0.05). Conclusion: The flexor hallucis longus transfer and turn-down of proximal Achilles tendon tissue repair can both get satisfactory results in treating chronic Achilles tendon rupture.

Anatomic and histological analyses of chiasma plantare and long flexor tendons of the foot on human fetuses

PURPOSE

The aim of present study was to reveal slip transfers related to flexor hallucis longus (FHL) and flexor digitorum longus (FDL) by dissection and to investigate detailed structure of chiasma plantare composed of FHL-FDL tendons and quadratus plantae (QP), with precise composition of the long flexor tendons of lesser toes by histological sections in human fetuses.

METHOD

Slip transfers related to FHL and FDL tendons were identified and the related morphometric measurements were taken with dissection in 28 formalin-fixed fetuses (25-40 weeks). Composition and restoration of chiasma plantare and long flexor tendons of lesser toes were traced histological by analyzing movements of the tissues on the sequential coronal sections in five fetuses in the third trimester. The numbers of layers constituting chiasma plantare and the muscles that formed layers were specified. Each of two to five flexor tendons arising from the chiasma plantare was analyzed regarding its formation and contribution of FHL slip.

RESULTS

Slip transfers were found as FHL slip in 86% and cross-connections in 14%. The ratios of the slip width to that of FHL and FDL tendons were found higher than in adult literature. Variance in the involvement of slip to FDL and QP, formation and layering of chiasma plantare and formation of long flexor tendons from chiasma plantare were revealed and great similarities were found with data from dissection of adult in literature.

CONCLUSION

Slip transfers between FHL and FDL tendons, and layering properties of chiasma plantare were largely finalized during intrauterine period, while structural changes in slip seem to continue in the later stages of life, possibly by the effects of growth and usage of the extremity. In addition to individual variations, investigating the contribution of FHL slip, FDL and QP to long flexor tendons by different methods in literature is also suggested to be responsible for some diversities of our histological study.

How does ballet training alter ankle tendinous morphology and hemodynamics in asymptomatic pre-professional dancers? An ultrasonographic study

OBJECTIVES

Among symptomatic dancers, sonographic abnormalities are common. Whether asymptomatic dancers have any abnormalities remains unknown. Some dancers became cyanosis over distal feet after ballet training. The hemodynamic changes at the feet in ballet are not clearly understood.

DESIGN

Cross-sectional study.

METHODS

In 25 dancers and 14 non-dancers, B-mode ultrasonography was used to measure cross-sectional areas (CSA) of tendons of deep posterior compartment muscles. Doppler ultrasonography was used to measure peak velocity (V_peak) of posterior tibial artery in three ankle postures: the neutral position, passively and forced actively plantar flexion (en pointe). The big toe oxygen saturation was recorded in neutral position and during 1-min en pointe. Single-leg standing heel rise test was performed to represent the muscle function.

RESULTS

The CSA of FHL was larger in dancers (0.26cm² [0.20, 0.30] vs 0.21cm² [0.17, 0.24], p<0.01), while other tendons were not different (all p>0.05). Higher V_peak was recorded in passively plantar flexion than in neutral position (p<0.01, in both groups). The blood flow was undetectable during en pointe, more frequently in dancers (54.9% vs 14.3%, p<0.01). Oxygen saturation decreased during en pointe more prominently in dancers (85% [80, 90] vs 94% [84, 97], p<0.01). There was no significant difference in muscle function.

CONCLUSIONS

US showed the FHL tendon thickening and en pointe-related vascular compromise in pre-professional dancers, even when they are asymptomatic.

The application of fibular free flap with flexor hallucis longus in maxilla or mandible extensive defect: a comparison study with conventional flap

Background

The repair and reconstruction of maxillary and mandibular extensive defects have put huge challenges to surgeons. The fibular free flap (FFF) is one of the standard treatment choices for reconstruction. The conventional FFF has deficiencies, such as forming poor oral mucosa, limited flap tissue, and perforator vessel variation. To improve the use of FFF, we add the flexor hallucis longus (FHL) in the flap (FHL-FFF). In this paper, we described the advantage and indication of FHL-FFF and conducted a retrospective study to compare FHL-FFF and FFF without FHL.

Methods

Fifty-four patients who underwent FFF were enrolled and divided into two groups: nFHL group (using FFF without FHL, 38 patients) and FHL group (using FHL-FFF, 16 patients). The perioperative clinical data of patients was collected and analyzed.

Results

The flaps all survived in two groups. We mainly used FHL to fill dead space, and the donor-site morbidity was slight. In FHL group, flap harvesting time was shorter (118.63 ± 11.76 vs 125.74 ± 11.33 min, P = 0.042), the size of flap’s skin paddle was smaller (16.5 (0–96) vs 21.0(10–104) cm², P = 0.027) than nFHL group. There were no significant differences (P > 0.05) in hospital days, hospitalization expense, rate of perioperative complications, etc. between the two groups. Compared with FFF without FHL, FHL-FFF will neither affect the use of flap nor bring more problems.

Conclusion

The FHL-FFF simplifies the flap harvesting operation. The FHL can form good mucosa and make FFF rely less on skin paddle. It can be used for adding flap tissue and dealing with perforator vessel variation in reconstruction of maxillary and mandibular extensive defects.

Anatomical feasibility study of flexor hallucis longus transfer in treatment of Achilles tendon and posteromedial portal of ankle arthroscopy

PURPOSE

The aim of this study was to evaluate the occurrence of anatomical variations of the musculotendinous junction of the flexor hallucis longus (FHL) muscle, the relationship between FHL tendon or muscle and the tibial neurovascular bundle at the level of the posterior ankle joint in human cadavers.

METHODS

Seventy embalmed feet from 20 male and 15 female cadavers, the cadavers' mean age was 65.4 (range from 14 to 82) years, were dissected and anatomically classified to observe FHL muscle morphology define the relationship between FHL tendon or muscle and the tibial neurovascular bundle. The distance between the musculotendinous junction and the relationship between FHL tendon or muscle and the tibial neurovascular bundle was determined.

RESULTS

Three morphology types of FHL muscle were identified: a long lateral and shorter medial muscle belly, which was observed in 63 specimens (90%); equal length medial and lateral muscle bellies, this variant was only observed in five specimens (7.1%); one lateral and no medial muscle belly, which was observed in two specimens (2.9%). No statistically significant difference was observed according to gender or side (p > 0.05). Two patterns were identified and described between FHL tendon or muscle and the tibial neurovascular bundle. Pattern 1, the distance between the neurovascular bundle and FHL tendon was 3.46 mm (range 2.34-8.84, SD = 2.12) which was observed in 66 specimens (94.3%); Pattern 2, there was no distance which was observed in four specimens (5.7%).

CONCLUSION

Knowing FHL muscle morphology, variations provide new important insights into secure planning and execution of a FHL transfer for Achilles tendon defect as well as for the interpretation of ultrasound and magnetic resonance images. With posterior arthroscopic for the treatment of various ankle pathologies, posteromedial portal may be introduced into the posterior aspect of the ankle without gross injury to the tibial neurovascular structures because of the gap between the neurovascular bundle and FHL tendon.

Anatomy of Master Knot of Henry: A morphometric study on cadavers

Objective

The objective of this study was to evaluate the features of flexor hallucis longus (FHL), flexor digitorum longus (FDL) and flexor digitorum accessorius (FDA) muscles with relevance to the tendon grafts and to reveal the location of Master Knot of Henry (MKH).

Methods

Twenty feet from ten formalin fixed cadavers were dissected, which were in the inventory of Anatomy Department of Medicine Faculty, Mersin University. The location of MKH was identified. Interconnections of FHL and FDL were categorized. According to incision techniques, lengths of FHL and FDL tendon grafts were measured. Attachment sites of FDA were assessed.

Results

MKH was 12.61 ± 1.11 cm proximal to first interphalangeal joint, 1.75 ± 0.39 cm below to navicular tuberosity and 5.93 ± 0.74 cm distal to medial malleolus. The connections of FHL and FDL were classified in 7 types. Tendon graft lengths of FDL according to medial and plantar approaches were 6.14 ± 0.60 cm and 9.37 ± 0.77 cm, respectively. Tendon graft lengths of FHL according to single, double and minimal invasive incision techniques were 5.75 ± 0.63 cm, 7.03 ± 0.86 cm and 20.22 ± 1.32 cm, respectively. FDA was found to be inserting to FHL slips in all cases and it inserted to various surfaces of FDL.

Conclusion

The exact location of MKH and slips was determined. Two new connections not recorded in literature were found. It was observed that the main attachment site of FDA was the FHL slips. The surgical awareness of connections between the FHL, FDL and FDA, which participated in the formation of long flexor tendons of toes, could be important for reducing possible loss of function after tendon transfers postoperatively.

What Do You Do With The Achilles if You Have No Fancy Toys?

Surgical management of Achilles disorders warrants excision of the degenerated tendon and removal of impinging bone. Resulting defects can be bridged by various methods. Although FHL is the most commonly used tendon for transfer, large defects in cases of chronic Achilles ruptures may be bridged by use of a distant donor tendon. Bony anchorage of a lengthened or transferred tendon into the calcaneus can be done with suture anchors or with interference screws. In developing countries, such implants may not be available or affordable, necessitating the adoption of innovative ways to anchor tendons into the calcaneus.

Tendon split lengthening technique for flexor hallucis longus tendon rupture

Background

Flexor hallucis longus (FHL) tendon rupture is a challenging injury to lead with clawing of the great toe when the FHL tendon is repaired too tight. When the diagnosis is delayed, the tendon ends may not be opposable because of contracture or poor tendon tissue.

Methods

A technique to reconstruct FHL tendon rupture without a free tendon graft is described. A split tendon lengthening is performed at the midfoot around the knot of Henry. Ankle block anesthesia is used to allow the patient’s active movement of the interphalangeal (IP) joint to determine the appropriate length of the reconstructed tendon for maintaining balance and preventing the tendon from being too tight or too loose. Between May 2012 and September 2015, five patients with a total rupture of the FHL tendon, having tendon defect distal to the knot of Henry, were treated with split tendon lengthening.

Results

Four patients could actively plantarflex the great toe IP joint. One patient who was operated under spinal anesthesia could not actively plantarflex the great toe IP joint, but did not have extension deformity and did not want another procedure. The mean American Orthopedic Foot and Ankle Society (AOFAS) score at a mean follow-up of 44 months was 92 points (range, 80–100).

Conclusions

This technique is described to overcome the difficulty of reconstructing the FHL tendon with tendon defect. The tendon defect could be repaired after split tendon lengthening without a free tendon graft.

Anatomical variations of flexor hallucis longus tendon increase safety in hindfoot endoscopy

PURPOSE

The flexor hallucis longus (FHL) tendon is the main anatomical landmark during hindfoot endoscopy, and anatomical variations related to the FHL can pose a risk to the tibial nerve and posterior tibial vessels during hindfoot endoscopy. The aim of this study was to determine the distance between the FHL tendon and the tibial neurovascular bundle in the posterior ankle joint when an anatomical variant of the FHL is present. The hypothesis was that the shortest distance between the tibial neurovascular bundle and the FHL tendon in the working area of the hindfoot endoscopy is increased when an anatomical variant of the FHL is present.

METHODS

A retrospective review was performed using consecutive ankle magnetic resonance imaging (MRI) scans obtained during 1 year. All scans with anatomical variations related to the FHL were included in the study. A control group including scans without anatomical variations was obtained for comparison. The shortest distance between the FHL tendon and the neurovascular tibial bundle was measured in both groups.

RESULTS

Three-hundred and fifty-five ankle MRIs were reviewed. 35 scans with anatomical variants of the FHL (9.8%) were found and comprised the study group that was compared to 35 scans without variants (control group). The mean distance from FHL to the neurovascular tibial bundle in the control group was 0.9 mm. The study group consisted of 18 cases with distal muscle belly insertion (5.1%), and 17 cases with an accessory tendon corresponding to a flexor digitorum accessorius longus (4.5%). In these subgroups, the mean distance from FHL to the neurovascular tibial bundle was 1.1 and 1.5 mm respectively. Overall this distance was found to be higher in the group with anatomical variants (1.3 mm) when compared to the control group (0.9 mm) (p < 0.05).

CONCLUSION

During hindfoot endoscopy, the presence of an anatomical variant related to the FHL tendon has proven safer anatomically than in its absence, due to the increased distance between the FHL tendon and the tibial neurovascular bundle in the working area. However, the minimal difference observed in safety distances still poses a major risk of injury during hindfoot endoscopic procedures in all cases.

The reliability of shear elastic modulus measurement of the ankle plantar flexion muscles is higher at dorsiflexed position of the ankle

Background

Excessive stiffness of lower limb muscles is associated with sports injuries. Therefore, the identification of a reliable measurement of the shear elastic modulus of various ankle plantar flexion muscles is required to evaluate lower leg sports injuries. This study investigated the reliable measurement of the shear elastic modulus of the ankle plantar flexion muscles at different ankle positions.

Methods

Twenty-three healthy young men (25.3 ± 3.6 years, 172.9 ± 5.0 cm, 67.2 ± 7.2 kg) participated in this study. The shear elastic moduli of the ankle plantar flexion muscles including the lateral gastrocnemius, medial gastrocnemius, soleus, peroneus longus, peroneus brevis, flexor hallucis longus, flexor digitorum longus and tibialis posterior were measured using ultrasonic shear wave elastography at 0, 10 and 20° dorsiflexion.

Results

The reliability of the shear elastic modulus measurements for each ankle position was assessed. The results showed that the interday reliability of the measurements differed between ankle positions and that the reliability of the shear elastic modulus measurements at 20° dorsiflexion was higher than that at 10° or 0°.

Conclusion

Our results suggest that measurements at 20° dorsiflexion may provide a more reliable measurement of the shear elastic modulus of ankle plantar flexion muscles.

Ankle and toe muscle strength characteristics in runners with a history of medial tibial stress syndrome

Background

A high proportion of flexor digitorum longus attachment is found at the posteromedial border of the tibia, which is the most common location of medial tibial stress syndrome (MTSS). Therefore, plantar flexion strength of the lesser toes could be related to MTSS; however, the relationship between MTSS and muscle strength of the hallux and lesser toes is not yet evaluated due to the lack of quantitative methods. This study investigated the muscle strength characteristics in runners with a history of MTSS by using a newly developed device to measure the muscle strength of the hallux, lesser toes, and ankle.

Methods

This study comprised 27 collegiate male runner participants (20.0 ± 1.6 years, 172.1 ± 5.1 cm, 57.5 ± 4.0 kg). Maximal voluntary isometric contraction (MVIC) torque of the plantar flexion, dorsiflexion, inversion, and eversion of the ankle were measured by using an electric dynamometer. MVIC torque of the 1st metatarsophalangeal joint (MTPJ) and 2nd–5th MTPJ were measured by using a custom-made torque-measuring device. MVIC torques were compared between runners with and without a history of MTSS.

Results

MVIC torque of the 1st MTPJ plantar flexion was significantly higher in runners with a history of MTSS than in those without it. In contrast, there were no significant differences in the MVIC torque values of the 2nd–5th MTPJ plantar flexion and each MVIC torque of the ankle between runners with and without a history of MTSS.

Conclusion

A history of MTSS increased the isometric FHL strength.

The high variability of the chiasma plantare and the long flexor tendons: Anatomical aspects of tendon transfer in foot surgery

As tendon transfer of the flexor hallucis longus (FHL) and the flexor digitorum longus (FDL) is an established procedure, exact knowledge of the formation of the chiasma plantare is of great interest. Although the quadratus plantae (QP) appears to play a major role, it has been rarely addressed in previous studies. The aim of the present study was to reinvestigate the formation of the chiasma plantare and the composition of the long flexor tendons in order to clarify the inexact and partly contradictory descriptions published from 1865 onward. The chiasma plantare and the long flexor tendons in both feet of 50 formalin-fixed specimens of body donors (25 men and women) were analyzed by gross anatomical dissection. It was composed of one (3%), two (69%) or three layers (28%) which were variably established by the tendinous and muscular fibers of the FHL, the FDL and the QP. In 61% the FHL gave one or more slips to the FDL, and in 39% there was a bidirectional interconnection between the two tendons. The slip from the FHL to the FDL largely reinforces the second (45%), or the second and third tendon (46%). Thus, the FHL is involved in the first tendon in all cases, in the second one in 97% of cases, and in the third tendon in about one half of cases (53%). In all instances, the FDL contributes to the third to fourth, in 98% the second, and in at least 39% to the first tendon. The QP reinforces the second to fourth tendon in nearly all cases, the fifth in about one half of cases, and even the first tendon in 14% of cases. In addition, the individual composition of the five long flexor tendons arising from the chiasma plantare was analyzed in detail. Special emphasis was placed on the evaluation of side and sex differences as well as individual symmetry. Furthermore, biomechanical, developmental and phylogenetic aspects were outlined. In terms of the outcome of this study, the FHL appears to be the better donor for tendon transfer to restore lost function, but harvesting the FDL seems to be more suitable to prevent long-term functional damage. The decision depends on the individual patient's needs and should be made with due care.

Entrapment of the flexor hallucis longus tendon following ankle arthrodesis

Impingement following arthroscopic ankle arthrodesis has not been reported in the literature previously. We present a case report of a 68-year-old male 9 months following an uncomplicated arthroscopic ankle fusion presenting with persistent posteromedial ankle pain. Flexor hallucis longus (FHL) tendon impingement resulting from a prominent os trigonum was identified. This was successfully treated utilising hindfoot endoscopy with excision of the os trigonum and FHL release.

Tenosynovial chondromatosis of the flexor hallucis longus in a 17-year-old girl

Tenosynovial chondromatosis is a benign chondrogenic metaplasia of extra-articular synovial tissue. The most common locations for tenosynovial chondromatosis to develop are the hands and feet. The condition has rarely been reported in children. We present a case of tenosynovial chondromatosis of the flexor hallucis longus in a 17-year-old girl. The presentation was unusual not only due to the location and young age of the patient but also the absence of any palpable mass on physical exam and complete lack of calcification of the cartilage bodies. Initial diagnosis was made by MRI. The patient underwent tenosynovectomy with an excellent postoperative recovery at 6-month follow-up. Histopathology confirmed the diagnosis of tenosynovial chondromatosis.

Disorders of the Flexor Hallucis Longus and Os Trigonum

Os trigonum syndrome with disease of the flexor hallucis longus tendon, so-called stenosing flexor tenosynovitis, is a common cause of posterior ankle impingement. Conservative treatment is the recommended first line of treatment, with secondary treatment options of either open or arthroscopic os trigonum excision with flexor hallucis longus retinaculum release. The arthroscopic approaches have gained popularity in the past decade because of less scarring, less postoperative pain, minimal overall morbidity, and earlier return to activities. However, comprehensive understanding of the anatomy of the posterior ankle is crucial to warrant successful outcomes and minimizing complications.

Hindfoot endoscopy for posterior ankle impingement syndrome and flexor hallucis longus tendon disorders

Hindfoot endoscopic surgery is an alternative to conventional open surgery for treatment of posterior ankle pain. This procedure can be applied not only for accurate diagnosis under direct visualization but also for low-invasive therapy. Common indications for hindfoot endoscopy are posterior ankle impingement syndrome and damaged soft tissue. Several studies have reported good clinical outcomes of hindfoot endoscopy with lower complication rates than in the conventional open procedure. Nerve injury remains a common complication. To avoid such injury, make a posterolateral portal just lateral to the Achilles tendon and perform the hindfoot endoscopic procedure in the region lateral to the flexor hallucis longus tendon.

Adhesion of flexor hallucis longus at the site of a tibial-shaft fracture--a cause of a checkrein deformity

Post-traumatic adhesion of toe flexors at the tibial fracture site resulted in checkrein deformity is rare and only a few case reports or case series were reported in the English literature. Major differential diagnosis includes deep compartment syndrome or adhesion of the muscle due to various causes. We are not able to conclude what is the best treatment option. Open exploration and adhesiolysis at the adhesion site together with tendon lengthening at the distal tibial level is a feasible surgical option with satisfactory result.

Experimental evidence supporting isometric functioning of the extrinsic toe flexors during gait

BACKGROUND

The extrinsic toe flexors, flexor hallucis longus and flexor digitorum longus, play an important role in stabilizing the longitudinal arch and supporting high forefoot loads during the stance phase of gait. It was hypothesized that these muscles function isometrically during stance, a strategy thought to provide efficient energy transfer across adjoining body segments, but one for which there is little direct experimental evidence in vivo or in situ.

METHODS

Eight lower extremity cadavers were loaded into a robotic apparatus that simulates the kinematics and extrinsic muscle activity of the foot and distal tibia during the stance phase of gait. Instantaneous tendon excursions and forces of the extrinsic toe flexors, as well as plantar pressure distributions during stance, were measured under two muscle control strategies: (1) force feedback control, where tendon forces were matched to forces predicted from normal electromyographic patterns and (2) isometric displacement control, where the representative myotendinous junction was held in a constant location.

RESULTS

Tendon excursions of the flexor hallucis longus (7.18 (1.75)mm) and flexor digitorum longus (6.32 (1.74)mm) under force feedback control were small relative to optimal muscle fiber length (13.6% and 14.2%, respectively). Instantaneous tendon forces and plantar pressure variables were not different (P=0.112-0.912) between the two different muscle control strategies for either muscle.

INTERPRETATION

These findings suggest that the extrinsic toe flexors function isometrically during the stance phase of gait in vivo.