Flexor Digitorum Longus Tendon Research Articles

The diagnostic and therapeutic challenges of medial plantar neuropathy in jogger's foot: a case report

Jogger's foot is characterised by a neuropathic pain along the medial arch of the foot caused by compression of the medial plantar nerve. It is more common in runners, especially when there is an anatomical predisposition or some extrinsic factor that may exert compression on the nerve. This article presents the case of a 59-year-old man, who had pain and paraesthesia along the medial plantar arch of the left foot, lasting for several months. Despite having undergone some conservative treatments (plantar orthosis and physiotherapy) and minimal invasive procedures (cortico-anaesthetic injection and shockwave therapy) the symptoms persisted and amyotrophy of the abductor hallucis muscle became clinically evident. At this point, a magnetic resonance image was taken, showing compression of the medial plantar nerve at the intersection of the flexor hallucis longus and the flexor digitorum longus tendons. Ultrasound-guided treatment with pulsed radiofrequency of the medial plantar nerve was then proposed to try and modulate his chronic neuropathic pain. After the procedure, the patient reported immediate relief of the symptoms, which were maintained over 6 months of follow up after the procedure. This case report illustrates a rare and frequently misdiagnosed cause of midfoot pain and its management using electromagnetic modulation of peripheral nerves by pulsed radiofrequency. This seems to be an effective technique, with long-lasting results.

Targeted conditional collagen XII deletion alters tendon function

Collagen XII is a fibril-associated collagen with interrupted triple helices (FACIT). This non-fibrillar collagen is a homotrimer composed of three α1(XII) chains assembled into a collagenous molecule with a C terminal collagenous domain and a large N terminal non-collagenous domain. During tendon development and growth, collagen XII is broadly expressed throughout the extracellular matrix and enriched pericellularly around tenocytes. Tendons in a global Col12a1-/- knockout model demonstrated disrupted fibril and fiber structure and disordered tenocyte organization, highlighting the critical regulatory roles of collagen XII in determining tendon structure and function. However, muscle and bone also are affected in the collagen XII knockout model. Therefore, secondary effects on tendon due to involvement of bone and muscle may occur in the global knockout. The global knockout does not allow the definition of intrinsic mechanisms involving collagen XII in tendon versus extrinsic roles involving muscle and bone. To address this limitation, we created and characterized a conditional Col12a1-null mouse model to permit the spatial and temporal manipulation of Col12a1 expression. Collagen XII knockout was targeted to tendons by breeding conditional Col12a1flox/flox mice with Scleraxis-Cre (Scx-Cre) mice to yield a tendon-specific Col12a1-null mouse line, Col12a1Δten/Δten. Both mRNA and protein expression in Col12a1Δten/Δten mice decreased to near baseline levels in flexor digitorum longus tendons (FDL). Collagen XII immuno-localization revealed an absence of reactivity in the tendon proper, but there was reactivity in the cells of the surrounding peritenon. This supports a targeted knockout in tenocytes while peritenon cells from a non-tendon lineage were not targeted and retained collagen XII expression. The tendon-targeted, Col12a1Δten/Δtenmice had significantly reduced forelimb grip strength, altered gait and a significant decrease in biomechanical properties. While the observed decrease in tendon modulus suggests that differences in tendon material properties in the absence of Col12a1 expression underlie the functional deficiencies. Together, these findings suggest an intrinsic role for collagen XII critical for development of a functional tendon.

Anatomic Landmarks for Minimally Invasive Exposure for Flexor Digitorum Longus (FDL) Tendon Transfers and Spring Ligament Reconstruction

Category: Other; Basic Sciences/Biologics; Hindfoot; Midfoot/Forefoot Introduction/Purpose: The approach for identification of the FDL tendon is classically described through an incision proximal to the medial malleolus extending past the navicular following the inferior border of the first metatarsal.1This incision is lengthy, and we believe that the navicular tuberosity, medial malleolus, and/or sustentaculum tali can be used as reliable landmarks for identification of the FDL more precisely and reliably. The purpose of this study is to detail spatial anatomy of the medial arch to allow for a more reliable and less invasive exposure of the FDL. Methods: Ten cadaver specimens were used for a total of 20 extremities. Anatomic locations were identified and pinned with the foot positioned in neutral dorsiflexion. Anatomic locations pinned included tip of the anterior colliculus, navicular tuberosity, proximal portion of the sustentaculum tali, and the distal portion of the sustentaculum tali. Photographs were taken of each cadaveric specimen with pins in place. Image J calibrated software was then used to calculate the distance between anatomic points. Averages were calculated for all measurements. Results: On average the superior margin of the sustentaculum tali was located 8 mm from the FDL with a range of 5-15 mm. Average distance from inferior sustentaculum tali to the FDL was 9 mm with a range of 5-12 mm. Average distance from medial malleolus to superior FDL was 18 mm with a range of 11-27 mm. Average distance from medial malleolus to inferior FDL was 27 mm with a range of 20-36mm. Average distance from navicular tuberosity to anterior FDL was 22 mm with a range of 11-27 mm. Average distance from navicular tuberosity to posterior FDL was 30 mm with a range of 19-42 mm. Conclusion: The 'lighthouse' for the harvest of the FDL tendon is the sustentaculum tali. Intraoperatively, the FDL tendon is found 22-31 mm directly posterior to the navicular and 18-27 mm inferior to the medial malleolus. This provides a reliable anatomic region where a 40 mm oblique approach can be made to access the FDL and spring ligament complex for a more minimally invasive approach in all of the studied specimen.

‘Haleem's Hen’: A Mnemonic for the Anatomy of Hindfoot Structures at the Level of Sustentaculum Tali on Coronal T1-Weighted Magnetic Resonance Images

Category: Hindfoot; Ankle Introduction/Purpose: Magnetic resonance anatomy of the hindfoot as seen at the level of the sustentaculum tali is intricate due to surrounding muscles, tendons, aponeurosis and ligaments. The objective of this work is to provide a mnemonic with illustrative figures to simplify this complex anatomical region on coronal T1-weighted magnetic resonance images (T1-MRIs). Methods: One hundred and twenty-four patients referred for foot and ankle complaints were scanned utilizing standard MRI imaging protocols for evaluation of the hindfoot. Only coronal T1-MRIs of the calcaneus at the level of sustentaculum tali of unremarkably reported patients were selected for the development of this mnemonic. T1- and T2-MRIs of an additional set of patients with hindfoot pathologies were selected to demonstrate how this mnemonic is adapted to identify specific pathologies. Results: Upon viewing the calcaneus with the adjacent anatomical structures on coronal T1-MRIs, the overall appearance resembles a ''Hen in the Nest with Four Eggs.'' The calcaneus represents the body of the hen, while the sustentaculum tali forms the head and neck. The posterior tibial tendon represents the crest of the hen, and the flexor digitorum longus and flexor hallucis longus tendons represent its beak and wattle, respectively. The peroneus brevis and peroneus longus tendons represent the tail, and the long plantar ligament represents the flexed legs of Haleem's hen. The plantar aponeurosis represents the hen's nest. Whereas the abductor hallucis, flexor digitorum brevis, abductor digiti minimi and quadratus plantae muscles are the four eggs. Pes planus, flexor digitorum brevis hemangioma, Baxter's neuropathy associated with chronic denervation abductor digiti minimi atrophy and peroneal tendonitis are some of the hindfoot pathologies that can be identified utilizing the mnemonic. Conclusion: The mnemonic, 'Haleem's Hen in the Nest with Four Eggs,' serves as a simplified phrase for orthopedic surgeons, radiologists and other physicians to easily recall the anatomy of the hindfoot when viewing it at the level of the sustentaculum tali on coronal T1-MRIs. In addition, this mnemonic could be particularly useful when utilized in medical education curriculum for residents, fellows, and medical students. Further research is required to validate this mnemonic as an educational tool in medical training and detail additional hindfoot pathologies that can be identified with it.

Anthropometric and Clinical Analyses of the Distal Tibia, Posterior Tibial Tendon, and Flexor Digitorum Longus Tendon on MRI.

To determine the gender and age differences in posterior tibial tendon (PTT), flexor digitorum longus tendon (FDLT), medial malleolar groove (MMG), and posterior, anterior, and total posterior malleolus (PMP, APM, and TPM, respectively) and evaluate the use of these parameters for posterior malleolus plating. Descriptive study. Department of Radiology, Etimesgut Şehit Sait Ertürk State Hospital, Ankara, Turkey, from January to December 2020. The magnetic resonance images (MRI) of the ankle were evaluated. PTT and FDLT thickness and width, MMG depth, width, length, and groove opening angle, and APM, TPM, and PPM length were measured. Receiver operating characteristic analysis was conducted to determine whether the variables differed between gender and age. The study included 103 patients (61 women, 42 men). For gender discrimination, the sensitivity, specificity, and cut-off values were 78.6%, 72.1%, and 7.48 mm, respectively. For the PTT width: 76.2%, 77%, and 3.88 mm, respectively; for the PTT thickness: 85.7%, 86.9%, and 40.41 mm, respectively; and for the APM length, the APM, TPM, and PPM length measurements were statistically and significantly differed between the genders (p<0.001). The APM/PPM ratio was 0.47±0.057 mm in women and 0.47±0.060 mm in men, and TPM/PPM was determined as 0.55±0.604 mm and 0.56±0.657 mm. There was a statistically significant weak positive correlation among the age, MMG length, and FDLT width. The groove depth and width, PTT and FDLT width and thickness, and TPM, PPM, and APM length can be used in gender prediction. The APM/PPM ratio can be calculated to determine the plating length in posterior malleolus fractures. Medial malleolar groove, Posterior tibial tendon, Flexor digitorum longus tendon, posterior malleolus, MRI.

Clinical anatomical study on the treatment of tarsal tunnel syndrome with four-point vertical acupotomy

To explore safety and accuracy of four-point acupotomy for the treatment of tarsal tunnel syndrome regarding release of ankle tunnel flexor retinaculum to provide an anatomical basis of clinical treatment. Twenty-nine adult specimens (15 males and 14 females) fixed with 10% formalin, aged from 47 to 98 years old with an average age of (81.10±11.14) years old, 29 on the right side and 29 on the left side, which were selected for the study from September 2020 to October 2020. Simulate the operation of loosening flexor retinaculumt with a needle knife on the human specimen, and place the specimen on the frog position of lower limbs with medial malleolus upward to determine the center of medial malleolus. Choose 4 different positions near the flexor retinaculum to insert the needle so that the needle body was perpendicular to skin and cutting edge direction was perpendicular to the running direction of the flexor retinaculum. The needle knife penetrates the skin and explores slowly. When the flexor retinaculum was reached, the needle tip may touch the tough tissue. At this time, the cutting is loosened for 4 times. After acupotomy release operation was completed, make a lateral incision on the skin surface along acupotomy direction, open the area of the exposed flexor retinaculum, dissecting layer by layer, observe and record the needle knife and its surrounding anatomical structure. The length of acupotomy cutting marks of flexor retinaculum was measured by electronic vernier caliper. The safety and accuracy of acupotomy loosening of ankle canal flexor retinaculum were evaluated by observing the number and degree of ankle canal contents such as tendons and nerves injured by needle knife. The safety is to count the number of cases of acupotomy injury to the contents of the ankle canal, and to calculate the injury rate, that is, the number of injury cases/total cases × 100%. The effective release was defined as the release length L ≥ W/2(W is the width of the flexor retinaculum, defined as 20 mm). For safety, there were no acupotomy injuries to nerves or blood vessels in 58 cases, 26 cases injuried to posterior tibial tendon which 17 of these tendon injury cases, the tendon was penetrated and severely injured, and flexor digitorum longus tendon was injured in 12 cases. Among these cases, tendon was penetrated and severely injured in 4 cases, and total injury rate was 32.14%. No nerve and vessel injury on c3 and c4 point. For accuracy, 58 specimens were successfully released. The length Lc of releasing trace for acupotomy was (10.40±1.36) cm, and length range 6.38 to 12.88 cm. Among all cases, the length of releasing trace was ≥10 mm in 37 cases. The overall success rate of release was 100.00%. Layered structure of ankle tube flexor retinaculumt:fiber diaphragm from flexor retinaculum divides contents of ankle tube into different chambers inward, and fiber diaphragm meets here to synthesize a complete flexor retinaculum at the midpoint of the line between the medial malleolus tip and calcaneal tubercle(above the neurovascular course). Four-point needle-knife method of releasing flexor retinaculum for the treatment of tarsal tunnel syndrome is performed at the attachment of the two ends of flexor retinaculum;the tendon, but not the nerves and blood vessels, is easily damaged. It is safe to insert needle on the side of calcaneus. The extent of release is relatively complete, but due to the "layered" structure of the flexor retinaculum, classic surgical technique could only release one layer of flexor retinaculum when a needle is inserted at the edge of the bone and cannot achieve complete release of the full thickness of the flexor. Therefore, it remains to be determined whether the desired effect can be achieved clinically.

Histologic grading correlates with inflammatory biomarkers in tibialis posterior tendon dysfunction

BackgroundIt has been theorized that tibialis posterior tendon dysfunction (TPTD) is a degenerative process unrelated to inflammation. The purpose of this study was to determine if inflammatory cytokines, matrix metalloproteases (MMPs), and glutamate were elevated in diseased tibialis posterior tendons (TPTs). MethodsMatched diseased TPT, TPT insertion, and flexor digitorum longus (FDL) samples were collected from 21 patients. The samples were individually incubated in media, which was analyzed for inflammatory cytokines, MMPs, and glutamate. Histology and statistical analyses were performed. ResultsDiseased TPT and TPT insertion were significantly elevated compared to transferred FDL in eight inflammatory markers (p < 0.005). Only the diseased TPT was significantly elevated compared to the transferred FDL tendons for glutamate (p < 0.01). Histologic grading correlated with inflammatory cytokine levels. ConclusionDiseased TPT and TPT insertion demonstrated significantly elevated levels of inflammatory markers compared to the transferred tendons used as controls, suggesting a role for inflammation in the disease process. The amount of inflammation correlated with increased tendon degradation. Level of evidenceLevel III

Sensation of Anteroposterior and Lateral Body Tilt Induced by Electrical Stimulation of Ankle Tendons

While virtual reality technology enables users to walk on surfaces of various shapes in virtual environments, these experiences are often on a flat floor, and any discordance between visual and somatosensory information hampers the immersive experience. To resolve this issue, we have focused on the ankle joint angle as an essential cue in detecting the surface shape of the ground. To modulate the sensation of the ankle joint angle, we propose novel percutaneous electrical stimulation methods that stimulate four targeted ankle tendons: the tibialis anterior muscle tendon, the Achilles tendon, the peroneus longus muscle tendon, and the flexor digitorum longus tendon. Since electrically stimulating the elbow tendon is known to evoke reflexive hand movement, electrically stimulating the ankle tendon is expected to evoke a body tilt due to illusory changes in the ankle joint angle. In this study, we designed electrode configurations to stimulate the above four ankle tendons using a finite element analysis and investigated the effect of electrically stimulating the ankle tendons on the subjective sensation of body tilt and actual body sway through psychophysical experiments. The results revealed that applying this stimulation with our novel electrode configurations can induce a subjective sensation of body tilt and actual body sway in a direction opposite to the stimulated part.

Characterization of scar tissue biomechanics during adult murine flexor tendon healing

Tendon injuries are very common and result in significant impairments in mobility and quality of life. During healing, tendons produce a scar at the injury site, characterized by abundant and disorganized extracellular matrix and by permanent deficits in mechanical integrity compared to healthy tendon. Although a significant amount of work has been done to understand the healing process of tendons and to develop potential therapeutics for tendon regeneration, there is still a significant gap in terms of assessing the direct effects of therapeutics on the functional and material quality specifically of the scar tissue, and thus, on the overall tendon healing process. In this study, we focused on characterizing the mechanical properties of only the scar tissue in flexor digitorum longus (FDL) tendons during the proliferative and early remodeling healing phases and comparing these properties with the mechanical properties of the composite healing tissue. Our method was sensitive enough to identify significant differences in structural and material properties between the scar and tendon-scar composite tissues. To account for possible inaccuracies due to the small aspect ratio of scar tissue, we also applied inverse finite element analysis (iFEA) to compute mechanical properties based on simulated tests with accurate specimen geometries and boundary conditions. We found that the scar tissue linear tangent moduli calculated from iFEA were not significantly different from those calculated experimentally at all healing timepoints, validating our experimental findings, and suggesting the assumptions in our experimental calculations were accurate. Taken together, this study first demonstrates that due to the presence of uninjured stubs, testing composite healing tendons without isolating the scar tissue overestimates the material properties of the scar itself. Second, our scar isolation method promises to enable more direct assessment of how different treatment regimens (e.g., cellular ablation, biomechanical and/or biochemical stimuli, tissue engineered scaffolds) affect scar tissue function and material quality in multiple different types of tendons.

Acute Medial Ankle Pain in a 17-Yr-Old Basketball Player.

This study conforms to all case report guidelines and reports the required information accordingly (see Supplementary Checklist, Supplemental Digital Content 1, https://links.lww.com/PHM/B586). A 17-yr-old male collegiate basketball player with no medical history presented one day after developing new-onset left medial ankle pain during a practice in which he took 700 consecutive jump shots. The pain progressed, eventually limiting his ability to bear weight. He denied any previous left lower limb injuries. Pertinent physical examination findings included focal tenderness over the distal tibia 4 cm proximal to the medial malleolus, pain with passive dorsiflexion/eversion, and pain with both resisted plantarflexion/inversion and toe flexion. There was no adjacent erythema or effusion about the ankle present. The differential diagnosis included distal tibia stress reaction/fracture, posterior tibialis (PT), or flexor digitorum longus (FDL) tendinopathy, and flexor retinaculum injury. Radiographs were negative. Magnetic resonance imaging (MRI) demonstrated fluid signal and edema about the distal PT and FDL myotendinous junctions, with grossly normal-appearing tendons (Fig. 1).FIGURE 1: Axial oblique (A and B) and sagittal oblique (C) T2-weighted MRI of the left ankle demonstrating fluid signal and edema about the distal PT and FDL myotendinous junctions (arrows) within the distal medial lower leg. Panel D demonstrates corresponding AP plain films of the left ankle. Ant, anterior; EDL, extensor digitorum longus; EHL, extensor hallucis longus; FHL, flexor hallucis longus; G-S-A, gastroc-soleus-Achilles complex; Inf, inferior; Lat, lateral; Med, medial; PB, peroneus brevis; PL, peroneus longus; Post; posterior; Sup, superior.The final diagnosis was chiasma crurale intersection syndrome. After MRI ruled out bone stress injury (no evidence of periosteal or bone marrow edema), he was started on a 7-day course of oral ibuprofen 400 mg 3 times daily. He was weaned from his walking boot over the course of 5 days guided by pain-free ambulation, after which he started progressive strengthening. Ibuprofen was not recommended until after the MRI to minimize possible impairment in bone healing, had there been a stress injury. At 3 wks after injury, he had returned to play without symptoms. Chiasma crurale refers to the intersection of the PT and FDL tendons. A symptomatic intersection syndrome at the crossover of these two tendons has not been previously reported. Theoretically, an intersection syndrome can develop at any point where two tendons cross and have no tendon sheath or paratenon separating them, as this predisposes them to increased friction forces and inflammation in the setting of overuse. Intersection syndromes elsewhere in the body have been reported, most notably where the 1st dorsal extensor compartment crosses over the 2nd in the forearm.1,2 Diagnosis can be confirmed through MRI or ultrasound. Ultrasound findings in intersection syndromes include anechoic fluid with loss of the hyperechoic plane separating the tendons and possible increased power Doppler signal.3,4 Cadaveric studies have found that the chiasma crurale has no intervening tissue at its center, making it a potential site for an intersection syndrome.5 On average, its center is located 4.2 cm above the tibiotalar joint.5 Gross irregularities of the tendons at the chiasma crurale may be seen on imaging, without histologic evidence of tendon degeneration.5 When this is the case, a concurrent symptomatic PT tendinopathy should be considered and clinically evaluated for, although classically that pain is present closer to the tendon’s distal insertion. Treatment of intersection syndromes is similar to that of other overuse conditions. Initially, activity modification and load management education are implemented, followed by progressive mobilization, strengthening, and incorporation of sport-specific activities in athletes.6 For cases recalcitrant to the above measures, a corticosteroid injection can be considered. Surgical release and debridement of inflamed tenosynovium are rarely needed but remain an option when nonoperative measures have been exhausted. TEACHING POINTS Chiasma crurale refers to the intersection of the PT and FDL tendons in the posteromedial distal leg. Magnetic resonance imaging findings of fluid signal and edema about the distal PT and FDL myotendinous junctions within the distal lower leg, coupled with grossly normal-appearing tendons, suggest inflammation from an intersection syndrome. Chiasma crurale intersection syndrome is a rare cause of medial ankle pain and is generally responsive to conservative treatment.

Flexor Digitorum Longus Transfer for Posterior Tibial Tendon Dysfunction is the Standard of Care: Does the Evidence Support It?

Category:Basic Sciences/Biologics; Hindfoot; OtherIntroduction/Purpose:Flexor digitorum longus (FDL) transfer, in conjunction with osseous procedures, is used routinely for the treatment of posterior tibial tendon dysfunction (PTTD). It is well established however that the relative power of the FDL tendon is significantly inferior than that of the native posterior tibial tendon. The purpose of this study is to systematically evaluate the evidence that supports or refutes the use of an FDL transfer in the surgical treatment of PTTD.Methods:A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta- Analysis. Using the terms 'flexor digitorum longus OR FDL AND posterior tibial tendon dysfunction OR PTTD OR adult acquired flatfoot OR AAFD' we searched the PubMed/Medline database. Both clinical and biomechanical studies were eligible for inclusion.Results:Forty-one studies met the inclusion criteria, including 31 clinical studies and 10 biomechanical in vitro studies. All 31 clinical studies consisted of Level IV evidence, and support the use of an FDL transfer. There was significant heterogeneity of the clinical evidence due to the variety of concomitant procedures. Of the 10 biomechanical in vitro studies, 2 support the use of an FDL transfer, although these did not assess the procedure in isolation. 8 biomechanical in vitro studies specifically assessing the effect on of an FDL transfer contradict its use for PTTD.Conclusion:There is poor quality clinical evidence to support the use of an FDL transfer for PTTD and the biomechanical literature refutes the use of the procedure. It remains unknown if the clinical improvement reported in the literature can be attributed to the FDL transfer or the concomitant osseous procedures. Additional studies are needed to assess the validity of the FDL transfer and whether alternatives are available to preserve the PTT muscle.

"Haleem’s Hen"; A mnemonic for the anatomy of hindfoot structures at the level of sustentaculum tali on coronal T1-weighted magnetic resonance images

Magnetic resonance anatomy of the hindfoot as seen at the level of the sustentaculum tali is intricate due to surrounding muscles, tendons, aponeurosis and ligaments. The objective of this work is to provide a mnemonic with illustrative figures to simplify this complex anatomical region on coronal T1-weighted MR images (T1-MRIs).One hundred and twenty-four patients referred for foot and ankle complaints were scanned utilizing standard MRI imaging protocols for depiction of the hindfoot. Only coronal T1-MRIs of the calcaneus at the level of sustentaculum tali of unremarkably reported patients were selected for this work.Upon viewing the calcaneus with the adjacent anatomical structures on coronal T1-MRIs, the overall appearance resembles a “Hen in the Nest with Four Eggs’’. The calcaneus represents the body of the hen, while the sustentaculum tali forms the head and neck. The posterior tibial tendon represents the crest of the hen, and the flexor digitorum longus and flexor hallucis longus tendons represent its beak and wattle, respectively. The peroneus brevis and peroneus longus tendons represent the tail, and the long plantar ligament represents the flexed legs of Haleem’s hen. The plantar aponeurosis represents the hen’s nest. Whereas the abductor hallucis, flexor digitorum brevis, abductor digiti minimi and quadratus plantae muscles are the four eggs.The mnemonic, “Haleem’s Hen in the Nest with Four Eggs”, serves as a simplified phrase for radiologists and orthopedic surgeons to easily recall the anatomy of the hindfoot when viewing it at the level of the sustentaculum tali on coronal T1-MRIs.

Posterior Hindfoot Endoscopy Using 1.9-mm Diameter Needle Arthroscopy: A Cadaveric Study

Category:Ankle; Arthroscopy; Hindfoot; SportsIntroduction/Purpose:Posterior hindfoot endoscopy is a safe and effective treatment for posterior ankle impingement syndrome (PAIS) and flexor hallucis longus (FHL) tendon disorders. As frequent coexistence of PAIS and FHL tenosynovitis has been reported, it is important to investigate FHL tendon pathology concomitantly when treating PAIS. However, the visualization of FHL tendon distal to the retinaculum is limited when using conventional rigid arthroscopy. Additionally, wound-healing problems following hindfoot endoscopy have been still reported. Recently, a novel 1.9-mm diameter needle-arthroscopic system has been introduced. Its small and semirigid features can help reduce the risk of wound complications and can make it easier to perform FHL tendoscopy. The purpose of this study was to assess whether 1.9-mm diameter needle-arthroscopy was useful for hindfoot endoscopy in a cadaveric model.Methods:A 1.9-mm diameter arthroscopic system (NanoScopeTM, Arthrex) was used to perform a hindfoot endoscopy in 6 human donor ankles (3 pairs). The arthroscope tube is 9.5-cm long and semi-rigid, and has a 1.9-mm outer diameter. The scope's direction of view is 0°, with a 120° field of view. Posteromedial and posterolateral portals were established. Visualization and operative reach with tailored arthroscopic instruments were recorded, including posterolateral talar process, posterior talofibular ligament, intermalleolar ligament, subtalar joint, ankle joint, and flexor hallucis longus (FHL) tendon. Finally, a conventional 4.0-mm diameter arthroscope with a 30° angle was used to compare the visualization of FHL tendon.Results:All significant structures were successfully visualized and reached in all specimens. In ankle joint, all of the tibial surface was visualized, but visualization of talar surface was limited. Due to its wide 120° field of view, there was no difficulty obtaining sufficient visualization in any structures. As this needle-arthroscopic system has the semirigid frame, FHL tendoscopy was easily performed via the posterolateral portal. In all specimens, the FHL tendon was visualized from the level of ankle joint to the Knot of Henry (Zone 1 and 2), and the flexor digitorum longus tendon crossing obliquely over the FHL tendon was observed (Figure). The conventional arthroscope could not be inserted into the tunnel underneath the sustentaculum tali in any specimens.Conclusion:Posterior hindfoot endoscopy using a 1.9-mm diameter needle-arthroscopy provides effective visualization and surgical reach of all significant structures for the treatment of PAIS. Its small and semirigid features also make the FHL tendoscopy less invasive and more accessible than conventional rigid arthroscope.

An Erratic Origin of Quadratus Plantae: An Embryological Error

Background: Quadratus plantae (Flexor digitorum accessorius) is one of the plantar muscles of foot . It is present in the second layer of sole. It takes origin from calcaneus and gets inserted into the tendon of flexor digitorum longus. The main function of it is to flex the lateral four toes in any position of the ankle joint by pulling on tendons of the flexor digitorum longus. Its variations like high origin have been implicated in the causation of tarsal tunnel syndrome. Methodology and Results: In routine dissection done on 22 cadavers, we observed a bilateral variant muscle flexor digitorum accessorius longus on both right and left sides in a male cadaver. The modality of choice in diagnosing the accessory muscle is magnetic resonance imaging. Conclusion: The knowledge of this variation would be essential to anatomists, radiologists and also to the foot surgeons while performing posterior ankle endoscopy. KEY WORDS: Flexor digitorum Accessorius longus, Tarsal tunnel syndrome, Posterior ankle endoscopy.

Development and growth of the foot lumbricalis muscle: a histological study using human foetuses.

Our group has shown early development of the hand lumbricalis and hypothesized that, at midterm, the lumbricalis (LU) bundles flexor tendons to provide a configuration of "one tendon per one finger" (Cho K.H. Folia Morphol. 2012; 71, 3: 154-163). However, the study concentrated on the hand and contained no sections of near-term foetuses. The present examination of paraffin-embedded tangential sections along the planta from 25 embryos and foetuses at 6-40 weeks (15-320 mm crown-rump length) demonstrated that, at 8 weeks, the initial foot LU appeared in the proximal side of the common tendinous plate of all five deep tendons. After midterm, a drastic three-phase change occurred at the muscle origin: 1) the LU originated from each of the flexor digitorum longus tendon (FDLT), but abundant tenocyte candidates separated the muscle fibre from the tendon collagen bundle; 2) the LU arose from the covering fascia depending on increased thickness of the muscle; and 3) the LU muscle fibres intermingled with tendon collagen bundles and partly surrounded the tendon. Simultaneously, a dividing site of the FDLT migrated distally to accelerate the changes at the LU origin. These phases did not always correspond to the size of foetus after 30 weeks. Consequently, in contrast to the hand LU, the delayed changes in the foot were characterised by involvement of the LU origin into a single common part of the FDLT. The quadratus plantae muscle fibres did not attach to the LU at any phase, and connected with the fourth and fifth toe tendons.

Irregularity in Plantar Fascia, Muscle Edema and Tendon Thickness in Patients with High-Risk for Diabetic Foot.

To investigate the alterations in the plantar fascia (PF), intrinsic muscles, and tendons in the feet of patients at high risk for developing diabetic foot. The healthy feet of 22 patients with type 2 diabetes, who had developed diabetic foot ulcers on a single foot without any pathology on the contralateral extremity, and those of 22 healthy volunteers were evaluated by magnetic resonance imaging. The volume of the Achilles tendon (AT), the surface area of the PF, the thickness of AT, flexor hallucis longus, flexor digitorum longus, tibialis posterior, and peroneus longus tendons, irregularity in the PF, and edema of intrinsic foot muscles were examined. Nineteen patients (86%) had irregularity in the PF, whereas none of the healthy controls had any (p<0.001). Intrinsic muscle edema was more common in the group with diabetes (p=0.006). The volume of AT and the surface area of PF were decreased in patients with peripheral arterial disease (PAD) (p<0.05). Patients with diabetes mellitus but without PAD had a larger surface area of PF than that of controls (p<0.05). There were no differences in the volume of AT, the surface area of the PF, and other tendon thickness between the groups. Irregularity in the PF and muscle edema may indicate a high risk for the diabetic foot. The presence of PAD may lead to regression in the structure of AT and PF.

Presence of adipose tissue along the posteromedial tibial border

PurposeThe flexor digitorum longus and posterior tibial tendon as well as the perforating veins are located along the distal posteromedial tibial border. Adipose tissue may surround these structures and possibly play a role in reducing mechanical stress. This study aimed to examine the adipose tissue along the posteromedial tibial border via magnetic resonance imaging (MRI), ultrasound, and gross anatomical examination.MethodsThe lower legs of 11 healthy individuals were examined every 3 cm from the medial malleolus using MRI and ultrasound. The fat fraction was calculated using fat fraction images. In addition, the gross anatomy of the flexor digitorum longus origin and adipose tissue along the posteromedial tibial border was examined in seven fresh cadavers. The fat fraction was compared at different heights along the posteromedial tibial border and in Kager’s fat pads; we also compared the height of the flexor digitorum longus origin and adipose tissue.ResultsIn vivo, the adipose tissue was identified along the entire posteromedial tibial border using MRI and ultrasound. There was no significant difference in fat fraction between Kager’s fat pads and the adipose tissue along the posteromedial tibial border, except at the 6 cm mark. All seven cadavers presented adipose tissue along the posteromedial tibial border, significantly more distal than the flexor digitorum longus origin.ConclusionThe adipose tissue was identified along the posteromedial tibial border via MRI, ultrasound, and gross anatomical examination; thus, this tissue may play a role in reducing friction and compressive stress in tendons.

TGF-\u03b23 regulates adhesion formation through the JNK/c-Jun pathway during flexor tendon healing

BackgroundThe injured flexor tendon has poor healing ability, which is easy to cause tendon adhesion. It can affect the recovery of tendon function, which is still a long-term and difficult task for surgeons. Transforming growth factor β (TGF-β) has been widely considered to play an important role in flexor tendon repair in recent years.AimThis work was to investigate the anti-adhesion and anti-inflammatory effects of TGF-β3 on flexor digitorum longus (FDL) tendon repair rats.MethodAnastomosis models of tendon laceration in the flexion toes of rats were delivered with no treatment, vehicle, or TGF-β3 -overexpressed adenovirus vector (ad-TGF-β3) locally to the injured tendon area from day 3 to 8. Subsequently, the expression of TGF-β3, TGF-β1/2, Smad3, Smad7, JNK, phosphorylation (p)-JNK, c-Jun, and phosphorylation (p)-c-Jun were detected by western blot, the expression of Mmp9 and Mmp2 by RT-qPCR, the Range of motion (ROM) and gliding resistance by adhesion formation testing, the mechanical strength of tendon healing by biomechanical testing, the pathologic changes of flexor tendon tissues by HE staining, the expression of collagen type III by immunohistochemical staining, and the levels of IL-6, TNF-α, COX2 and IL-1β in serum by ELISA, respectively.ResultsRat models treated with no treatment showed a lower elevation of TGF-β3 and Smad7 expression, and a higher elevation of TGF-β1/2 and Smad3 expression, during day 14 to day 28. Besides, under the treatment of ad-TGF-β3, a significantly increase was reflected in the expression of TGF-β3 and Smad7, ROM, as well as mechanical strength of flexor tendon, whereas significantly reduction was shown in gliding resistance, the content of inflammatory cytokines, the ratio of p-JNK/JNK, p-c-Jun/c-Jun, as well as the expression of TGF-β1/2, Smad3, Mmp9, and Mmp2 genes, as compared to those from vehicle treatment. Meanwhile, TGF-β3 demonstrated a better pathologic recovery process with no obvious necrosis or fracture of collagen fibers. Besides, TGF-β3 revealed a significant reduction of collagen type-III expression in the flexor tendon healing tissues.ConclusionThese findings suggested that TGF-β3 effectively protected against flexor tendon injury via regulating adhesion formation.

Unusual bilateral variation of the flexor digitorum accessorius longus muscle and its relation on tarsal tunnel syndrome.

During standard anatomical dissection for a medical anatomy course, we encountered an unusual bilateral variant of a unipennate flexor digitorum accessorius longus (FDAL) muscle, a supernumery muscle of the deep posterior leg and medial ankle. We documented the muscles course and measured the diameter and length of the FDAL muscle belly, as well as the full length of its tendinous attachments. On both right and left legs, the FDAL originated from the proximal posterior fibula and distal one-third of the flexor hallucis longus muscle. The tendon had a distal attachment on the flexor digitorum longus (FDL) tendon and traveled with the FDL tendon as it inserted on the third distal phalanx. The left FDAL full length was 42.54cm; the length of the muscle belly was 16.26cm; and the circumference of the muscle belly was 4.44cm. The right FDAL full length was 44.20cm; the length of muscle belly was 12.06; and the circumference (belly) was 4.44cm. Surrounding musculature and neurovasculature follow standard anatomical courses. This anatomical documentation provides opportunities for clinicians to consider mechanical influences of the FDAL on plantar foot function and further consider the accessory ankle muscles that have the potential to cause compressive neuropathies such as tarsal tunnel syndrome.

Macrophage-activating lipoprotein (MALP)-2 impairs the healing of partial tendon injuries in mice

Tendon injuries are accounted for up to 50% of musculoskeletal injuries and often result in poor outcomes. Inflammation is a major hallmark of tendon regeneration. Therefore, we analyzed in this study whether the topical application of the pro-inflammatory mediator macrophage-activating lipoprotein (MALP)-2 improves the healing of partial tendon injuries. C57BL/6 mice underwent a partial tenotomy of the flexor digitorum longus tendon of the left hind limb, which was treated with a solution containing either 0.5 µg MALP-2 or vehicle (control). Repetitive gait analyses were performed prior to the surgical intervention as well as postoperatively on days 1, 3, 7, 14 and 36. The structural stability of the tendons was biomechanically tested on day 7 and 36. In addition, Western blot analyses were performed on isolated tendons that were treated in vitro with MALP-2 or vehicle. In both groups, partial tenotomy resulted in a pathological gait pattern during the initial postoperative phase. On day 7, the gait pattern normalized in vehicle-treated animals, but not in MALP-2-treated mice. Moreover, the tendons of MALP-2-treated mice exhibited a significantly reduced biomechanical stiffness after 7 and 36 days when compared to controls. Western blot analyses revealed a significantly higher expression of heme oxygenase (HO)-1 and lower expression of cyclin D in MALP-2-treated tendons. These findings indicate that MALP-2 delays the healing of injured tendons most likely due to increased intracellular stress and suppressed cell proliferation in this naturally bradytrophic tissue. Hence, the application of MALP-2 cannot be recommended for the treatment of tendon injuries.