Flexor Hallucis Longus Tendon Research Articles

Anatomy of the Flexor Hallucis Longus and Its Relationship With Hallux Valgus: A Cadaveric Study.

Hallux valgus (HV) is a complex deformity, with many associated risk factors. The flexor hallucis longus (FHL) tendon is a dynamic and potentially deforming force as it bowstrings laterally with HV. We hypothesized that FHL is more laterally inserted in the distal phalanx in cadavers with HV; therefore, it might be also a primary destabilizing force. We aim to compare the FHL distal insertion morphology and its relationship with osseous structures in cadavers with and without HV. Sixteen cadaver specimens, 8 with HV and 8 without (N-HV) were dissected. We evaluated FHL distal morphology in terms of its insertional footprint location and FHL long-axis position in relation to osseous anatomy. Both the HV and N-HV groups displayed a laterally inserted footprint at the distal phalanx, with the HV group exhibiting median lateral translation of the footprint 6% greater than the N-HV group (P < .01). Both groups also demonstrated a laterally displaced position for the FHL long axis. The median FHL long axis for HV vs N-HV specimens 1 cm proximal to the IP joint was 9% more laterally displaced from the midaxis (P < .01), and at 1 cm proximal to the MTP joint was measured to be 15% more laterally displaced from the midaxis (P < .01). FHL demonstrated an eccentric position in terms of insertion and trajectory in both the HV and N-HV groups, with greater lateralization in specimens exhibiting HV deformity. This eccentricity potentially creates a greater deforming force vector contributing to the development of HV. The etiology and progression of HV deformity may include a lateralized insertion of the FHL tendon. Treatment implications remain unknown at this time.

Minimally-invasive lag screw fixation technique for posterior malleolus fractures: A cadaveric study

Anatomical reduction and lag screw fixation of posterior malleolar (PM) ankle fractures typically involves an open posterolateral approach. The aim of this anatomical study was to assess whether a minimally-invasive, percutaneous posterior-to-anterior lag screw fixation technique is safe to perform. Eighteen cadaveric ankle specimens were used. A transverse incision was made at the lateral border of the Tendo Achilles (TA). Windows were made lateral to and through the substance of the TA and simulated reduction and placement of a single lag screw performed. Specimens were then fully dissected to ascertain proximity and damage to anatomical structures. Lag screw fixation was placed appropriately in all ankles. No injury to the neurovascular structures, ankle joint or syndesmotic ligaments was observed. The mean distance from the soft tissue window to sural nerve was 10.0 mm (range 5–16), and 9.5 mm to short saphenous vein (4–14). Whilst the muscle belly of flexor hallucis longus (FHL) was pierced in six specimens, no injuries to the FHL tendon were observed. The mean distance from screw to syndesmosis was 9.3 mm (range 3–15) and 12.7 mm to the ankle joint (7–17). This study demonstrates that posterior percutaneous lag screw fixation is both safe and accurate. Further work is required to evaluate the precision of reduction and the biomechanical stability of this fixation technique. This novel minimally-invasive technique may be beneficial in avoiding the wound complications associated with open posterolateral ankle approaches and also offer a functional advantage due to minimal soft tissue disruption.

Chronic Achilles Tendon Avulsion Repair: Central Third Fascia Slide Technique with Flexor Hallucis Longus Transfer.

Chronic Achilles Tendon Avulsion Repair: Central Third Fascia Slide Technique with Flexor Hallucis Longus Transfer.

Treatment of Dynamic Claw Toe Deformity Through Lengthening of the Flexor Tendons of the Hallux and Toes at the Midfoot Level.

The claw toe deformity is characterized by the flexion of interphalangeal joints (IPJs) with hyperextension of the metatarsophalangeal (MTP) joint. It can be flexible and reducible or rigid and irreducible, or dynamic. The most common cause of dynamic claw toes is a neurological disorder, like sequelae of an ischemic contracture of the muscle belly after a compartment syndrome. Most of the surgical techniques require multiple procedures and may be associated with complications such as toe stiffness, persisting metatarsalgia, and toe malalignment. The aim of this study is to present an option for the surgical treatment of the dynamic claw toe deformity, by simultaneous tenodesis and lengthening of the flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendons at Henry's knot through a single midfoot incision.Levels of Evidence: V; Therapeutic Study; Expert Opinion.

Release of retromalleolar flexor retinaculum and combined flexor digitorum longus and flexor hallucis longus Z-plasty in checkrein deformity: a case report

BackgroundCheckrein deformity is a rare abnormality comprising flexor hallucis longus (FHL) tendon entrapment in the posterior foot due to post-traumatic or ischemic retraction of the FHLtendon following soft tissue trauma. The diagnosis is essentially clinical, but complemented by imaging to rule out unrecognized causes and evaluate the fracture healing process. This case report is the first Indonesian study to describe release of the flexor retinaculum and Z-plasty (lengthening) of flexor digitorum longus (FDL) and FHL tendons through a medial retromalleolar approach to repair the deformity. Case DescriptionWe present the case of a 51-year-old male who complained of clawing of his right first and second toes. The interest of this study lies in the fact that this patient had never experienced ankle or distal tibial fractures, only a trivial injury two years back when the patient kicked a stone at work and had a bruise on his right second toe with no fracture. Exploration of FHL tendons was performed at the level of the midfoot. The patient was planned for surgery with a medial retromalleolar ankle approach, which facilitates the release of the flexor retinaculum, in conjunction with a Z-tenotomy on the FHL and FDL tendons. ConclusionA correction was achieved, and two months post-surgery there were no recurrences of the deformity. However, this surgical procedure requires more cases to support an evaluation of its effectiveness. We suggest that exploration at the ankle and midfoot should be the primary surgical intervention in similar cases of checkrein deformity.

The compensatory hypertrophy of transferred flexor hallucis longus tendon for insertional Achilles tendinopathy: a retrospective MRI study

Flexor hallucis longus (FHL) transfer is an effective surgery in treating insertional Achilles tendinopathy (IAT). However, limited data exist regarding the post-surgery changes in the transferred FHL. The study aimed to compare the sequential changes and hypertrophy of FHL after isolated FHL transfer (FHLT). We retrospectively enrolled patients who underwent isolated FHLT for insertional Achilles pathology from 2015 to 2020 and divided them into two groups based on whether reattachment of the residue Achilles stump to the FHL was performed or not. We recorded demographic characteristics, MRI parameters, and functional outcome. We also analyzed the correlation between the collected data and FHL hypertrophy. Results revealed no significant differences in most MRI parameters of FHL and functional outcomes between the groups. However, the fat distribution within the FHL showed significant reduction and notable 20.2% hypertrophy after FHLT. Interestingly, the hypertrophy of the FHL was significantly more pronounced in the non-reattached group. Furthermore, we observed a positive correlation between the follow-up period and FHL hypertrophy. In conclusion, the FHL demonstrated significant enlargement over time following FHLT. The compensatory hypertrophy of the transferred FHL was particularly evident and the cumulative incidences of FHL enlargement over time were higher in the non-reattached groupcompared to reattached group. However, both reattachment and non-reattachment of Achilles stump on FHL transfer for insertional Achilles tendinopathy carried similar postoperative functional outcomes.

Flexor Hallucis Longus Transfer And V-Y Plasty: An Effective Treatment Modality for Chronic Achilles Rupture - A Case Series.

To assess outcomes of FHL transfer and V-Y plasty for chronic Achilles rupture due to insertional Achilles tendinopathy. A case series of 12 patients was conducted between 1st January 2017 and 31st December 2018. The patients had short flexor hallucis longus tendon transfer with gastrocnemius lengthening by V-Y plasty for Achilles tendon rupture. Patients were allowed full weight bearing at six weeks post-operatively, and were followed up at three months and six months post-operatively, when the range of motion of the ankle was examined, and the outcome was assessed using the EFAS score. Of the 12 patients in the study, the majority were males; the mean age was 50.6±8.96 years. A significant improvement in dorsiflexion and plantarflexion was noted at the six-month follow-up compared to the three-month follow-up (P=<0.001 for both). When compared to the normal side, dorsiflexion and plantarflexion of the affected ankle were significantly less at three months but were comparable at six months post-operatively. A significant improvement was noted in the mean EFAS score at the six-month follow-up (25.5±5.71) compared to three months (18.6±0.90) post-surgery (P=0.001). Males were also noted to have significantly higher EFAS scores at their six-month follow-up than females (P=0.022). In contrast, a negative correlation was noted between the European Foot and Ankle Society (EFAS) score at the final follow-up and age (P=0.011). FHL tendon transfer with V-Y plasty in chronic Achilles rupture due to insertional Achilles tendinopathy is an effective procedure resulting in the restoration of the ankle range of motion and improvement in functional scores.

Exploring morphological variations and clinical significance of interconnections between flexor hallucis longus and flexor digitorum longus tendons

BackgroundThe tendons of the flexor hallucis longus (FHL) and flexor digitorum longus (FDL) are commonly utilized in reconstructive foot surgery to address deformities. These tendons intersect on the plantar surface and exhibit varying interconnections that can significantly impact graft length and complicate the tendon harvesting process. The objective of this study was to comprehensively categorize these interconnections using a modified classification system and precisely determine their positional relationships with surgically significant bony landmarks. MethodsSixty embalmed feet of 30 cadavers were studied to analyze the interconnections between FHL and FDL in the planta pedis, classify them in a modified classification system and measure distances to surgically relevant anatomic landmark. ResultsThe study revealed three primary types of interconnections. Type I, representing a proximal-to-distal connection from the FHL to the FDL, was observed in 85% of the feet. Type II, signifying a proximal-to-distal connection from the FDL to the FHL, was found in 11.66% of the feet. Type III, characterized by a crossed connection, was identified in 3.33% of the feet. The average point of branching for the FHL and FDL tendons was situated 4.5 cm and 3.5 cm distal to the navicular tuberosity, respectively. ConclusionThe presence of atypical proximal-to-distal interconnections from the FHL to the FDL may play a role in preserving residual function in the lesser toes following FDL transfer procedures. Awareness of anatomical variations in the location of these interconnections is crucial for preserving them during surgical interventions, ultimately mitigating the risk of functional impairment in the lateral toes post-tendon grafting.

Flexor Hallucis Longus decompression under ultrasound guidance: A cadaver study

IntroductionThe Flexor Hallucis Longus (FHL) is a muscle that can be subject to multiple impingements caused by exaggerated plantar flexion in athletes. The most common impingement is due to inflammation of the tendon at the retrotalar pulley. The constraints exerted on the FHL are responsible for a pathology called functional Hallux Limitus. Surgical treatment consists of tenolysis of the FHL arthroscopically or via open surgery, by opening the pulley. The objective of this study was to evaluate the risk of lesions of the neurovascular pedicle and the posterior tibial tendon after tenolysis of the Flexor Hallucis Longus under ultrasound guidance. HypothesisThe hypothesis of this study is that tenolysis of the Flexor Hallucis Longus could proceed under ultrasound guidance without associated tendon lesions or neurovascular lesions. Material and methodsThirteen cadaveric specimens were studied, resulting in an analysis of 26 feet. Following identification of the Flexor Hallucis Longus, tenolysis with a 19-gauge needle under ultrasound guidance was performed by an orthopedic specialist after hydrodissection to push back the posterior tibial pedicle. The dissection of the cadavers made it possible to verify the positioning of the posterior tibial pedicle, the FHL tendon and the opening of the retrotalar pulley. ResultsFive cadaveric subjects, 10 cases, underwent a complete opening of the retrotalar pulley under ultrasound guidance. In 16 cases, the opening was partial, with a section of the pulley of 65.87±18%. The cases of partial openings showed no neurovascular or tendinous lesions. The 10 cases of complete opening resulted in 5 lesions of the tibial nerve, 4 vascular lesions: 1 venous and 3 arterial, and 6 lesions of the FHL tendon. ConclusionTenolysis of the Flexor Hallucis Longus under ultrasound guidance at the level of its retrotalar pulley was systematically associated with neurovascular lesions in the event of complete release of the pulley by the method studied, unlike a partial release where no lesion was found. Level of EvidenceIII; case-control study.

Acute Achilles Tendon Ruptures Treated With Endoscopic Flexor Hallucis Longus Transfer

The Achilles tendon represents the most commonly ruptured tendon of the human body. Numerous studies have evaluated, throughout the years, management options regarding acute Achilles tendon rupture. Minimally invasive techniques have recently gained more popularity. Endoscopic flexor hallucis longus tendon transfer has been mainly described as a treatment method for neglected Achilles tendon ruptures. However, it has recently been described as an applicable treatment option for acute Achilles tendon ruptures as well. Nevertheless, this procedure is technically quite demanding and should be performed by experienced surgeons. This technical note thoroughly describes the endoscopic flexor hallucis longus transfer technique for acute Achilles tendon ruptures, focusing on the most important technical aspects, thus attempting to simplify and render this procedure more widely accepted.

Transfer of the Flexor Hallucis Longus Tendon Improves Joint Kinematics of the Medial Column during Simulated Stance Phase in Progressive Collapsing Foot Deformity

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Medial longitudinal arch collapse is one of the key clinical and radiographic features of progressive collapsing foot deformity (PCFD) and can occur anywhere within its three constituents: first tarsometatarsal (TMT1), naviculo- cuneiform (NC), and talonavicular (TN) joints. Medial column osteotomy or fusion has typically been utilized to address this instability. A new procedure involving transferring the flexor hallucis longus (FHL) tendon to the 1st metatarsal base has shown promising results in restoring radiographic alignment of the entire medial column in conjunction with a hindfoot procedure. However, the mechanism of correction in a dynamic environment is unclear. Thus, this study examined the effect of medial column stabilization using FHL transfer on the foot and ankle kinematics during stance phase. Methods: Twelve mid-tibia cadaveric specimen (6 male; Age 48 ± 16 years) underwent stance phase simulations using a validated six-degree of freedom robotic gait simulator. Three conditions were tested each cadaveric specimen: pre-deformity (Intact), after creating a simulated progressive collapsing foot deformity (sPCFD), and after an FHL transfer (FHL). Motion capture cameras tracked the motion of retroreflective markers inserted into bones of the foot and ankle. The FHL transfer was performed on each specimen by harvesting the FHL tendon at its distal insertion and fixing it in the 1st metatarsal with a biotenodesis screw (Figure 1A). Outcome measures include joint rotations of the TMT1, NC, TN, subtalar, and ankle joint. Significant differences (p &lt; 0.05) in joint kinematics were statistically analyzed by constructing 95% confidence intervals of the repeated measures difference between both the sPCFD and FHL conditions and the intact condition. Results: The FHL condition demonstrated significant differences in the kinematics of the medial column compared to the sPCFD condition (Figure 1B). The TMT1 joint showed increased plantarflexion in early and late stance, as well as increased eversion during early and mid-stance. The NC joint demonstrated increased plantarflexion, eversion, and abduction during early stance. At the TN joint, there was increased inversion during early and late stance, as well as increased adduction during mid-stance. At the subtalar joint, subtalar eversion was decreased during early stance, and no significant differences were observed from the intact condition throughout stance. No differences were found in the ankle joint kinematics across all conditions. Conclusion: The results of our study demonstrate that the medial column stabilization procedure with FHL transfer can improve the kinematics of the medial column in sPCFD. Additionally, the correction at the TN and subtalar joint demonstrates the potential efficacy of this procedure for hindfoot correction. The correction occurred during the earlier stance phase as well when the FHL is not active, suggesting that this procedure provides correction in both a dynamic and static manner. This procedure can be used in conjunction with hindfoot corrective procedures in PCFD, particularly when preoperative imaging suggests multiple levels of instability within the medial column.

Integrity of the First Metatarsal Head Vascularization and Soft-Tissue Envelope Following Minimally Invasive Chevron Osteotomy for Hallux Valgus (HV) Deformity: A Micro-CT and Anatomical Assessment

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Minimally invasive surgery (MIS) Chevron-osteotomy for HV treatment offers a surgical alternative to open surgery with minimal surgical dissection and a hypothetical decreased risk for soft-tissue complications. During this procedure, there is a concern regarding the injury to the blood supply of the 1st-metatarsal-head. The objective of this study was to assess the incidence of injuries: (1) to the soft-tissue envelope around the first metatarsal head complex and, (2) to the blood supply of the first metatarsal head and also by using Micro-CT, (3) looking for safe zones close to the first metatarsal head to perform MIS Chevron osteotomy. We hypothesized that the MIS Chevron-type osteotomy procedure would preserve the soft-tissue envelope of the first-metatarsal-head complex and the blood supply of the 1st-metatarsal-head. Methods: Sixteen HV deformity cadaveric specimens were used to perform MIS Chevron-type osteotomy of the first metatarsal head. Anatomical dissection of all specimens was then performed to assess macroscopic injury to the first metatarsal head complex soft-tissue structures, including Extensor Hallucis Longus (EHL) tendon, Extensor Hallucis Brevis (EHB) tendon, Flexor Hallucis Longus (FHL) tendon, Flexor Hallucis Brevis (FHB) tendon, Abductor Hallucis tendon, Adductor Hallucis tendon, Sesamoid complex, Dorsolateral and Dorsomedial digital branches of the first toe and the Dorsomedial digital branch to the second. Macroscopic injuries were classified using a calibrated digital caliper. Any chondral damage to the first metatarsal head was quantified in mm². To assess the amount of first metatarsal head blood supply, specimens were perfused with 200 ml of a low viscosity radiopaque polymer, MV 117 (Flowtech), preoperatively, followed by Micro-CT assessment. Descriptive statistics and percentages were utilized for categorical data. Results: We did not find injuries in the EHL, EHB, FHL, Abductor-Hallucis, and Adductor-Hallucis tendons. We found a 2mm injury in the FHB tendon in one specimen. No injuries were found in the Dorsomedial and Dorsolateral nerves of the first-toe, the Dorsomedial-nerve of the second-toe, and Medial branch of the dorsomedial-nerve of the first-toe. In 3 cases, we found an injury on first-metatarsal-head (1mm) due to the passage of the K-wire and, in 1 case, due to the inadvertent passage of the drill (4.41mm). Macroscopically and using Micro-CT, we did not observe injuries in the First-Dorsal-Metatarsal-Artery (FDMA), Lateral-Dorsal-Branch of FDMA, and Plantar-Metatarsal-Artery. Micro-CT helped estimate a safe distance to finish the proximal exit of Chevron-osteotomy (25mm from the most distal point of the first metatarsal head). Conclusion: In this study, the minimally invasive Chevron osteotomy for treating HV seems to be a technically safe procedure, presenting a low rate of iatrogenic injuries with a low degree of severity. In addition, using Micro-CT promoted a better visualization of the microvasculature that nourishes the first metatarsal head. We observed that a proximal distance of 25 mm from the most distal part of the first metatarsal head could be a safe place to finalize the Chevron osteotomy, minimizing the risk of injury to the blood supply of the first metatarsal head.

Long-term outcome of flexor hallucis longus tendon transfer for chronic Achilles tendon rupture with large defect: A retrospective series.

There are multiple surgical options for treatment of chronic Achilles tendon (AT) rupture according to the classifications and length of defect. However, no gold standard method has been confirmed, and there is no clear evidence to support the superiority of 1 procedure over others. This study aimed to evaluate the long-term clinical outcome of flexor hallucis longus tendon (FHL) transfer for chronic AT rupture with large defect. Clinical data of patients treated with FHL transfer due to chronic AT rupture between January 2009 and October 2019 were reviewed retrospectively. All cases were presented with AT rupture for more than 4 weeks after injury. The gap between ruptured ends was > 5 cm after debridement in all patients. The harvest of FHL was performed through a single incision in accordance with AT rupture debridement in all cases. Clinical outcomes were assessed with AOFAS ankle-hindfoot scale, Achilles tendon total rupture score and AOFAS hallux metatarsophalangeal-interphalangeal scale. Twenty-eight patients were followed successfully for 62.6 ± 22.2 months. According to the complete datasets obtained from 28 patients, none of the tendons re-ruptured. The AOFAS ankle-hindfoot scale and Achilles tendon total rupture score at last follow-up visit was 90.4 ± 5.7 and 89.8 ± 5.3 respectively, which revealed statistically significant improvement from the preoperative score of 61.1 ± 6.7 and 53.8 ± 8.3. The AOFAS hallux metatarsophalangeal-interphalangeal scale at last follow-up visit was 87.5 ± 6.1. The FHL transfer through a single incision for chronic AT rupture with large defect is a safe and simple method with low risk of morbidity and complications.

“Foot peak pressures are comparable to normal foot after flexor hallucis longus transfer for chronic retracted tendo-achilles tear: A pedobarographic analysis of normal foot versus affected foot”

IntroductionFoot pressure changes and morbidity after flexor hallucis longus (FHL) transfer in chronic retracted tendoachilles (TA) tears have not been documented. The primary aim of our study is to analyze the peak pressure changes in various zones of the foot at each successive follow-up in the affected foot versus normal foot. The secondary aim is to determine FHL tendon healing and muscle hypertrophy. MethodsThis is a prospective study of 46 patients who underwent FHL augmentation for chronic retracted TA tears (between 2019 and 2022). Included TA tear > 6 weeks duration and retraction > 2.5 cm. Excluded open TA tear, < 6 weeks and retraction < 2.5 cm. Depending on the amount of retraction, FHL augmentation combined with TA repair/VY plasty/turn-down-plasty. Functional outcome was analyzed with AOFAS hallux metatarsophalangeal scale. Pedobarographic analysis was done pre-operatively and at 3, 6, 9 months, 1 year and at the final follow-up. Parameters studied included forefoot peak pressure (FFPP), hindfoot peak pressure (HFPP), great toe peak pressure (GTPP), first Mmeta-tarso phalangeal peak pressure (MTPP), area under the pedobarograph and maximum force. At final follow-up MRI was done to assess FHL healing and hypertrophy. Statistical analysis was done for these parameters using appropriate tests. ResultsStudy involved 29 male and 17 female patients, mean age 49.5 years (33–65 years) and mean follow-up 26.8 months (14–38.4months). Mean hallux MTP-AOFAS score increased from 46.04 ± 7.31 preoperatively to 96.17 ± 3.22 at the final follow-up (P < 0.01). There was gradual improvement noted in FFPP, GTPP, MTPP Peak pressures at subsequent follow-ups, and by the end of 1-year foot pressures were comparable to normal side FFPP (8.02 ± 3.8 N/cm2 to 31.35 ± 3 N/cm2), GTPP(30.78 ± 13.01 N/cm2 to23.17 ± 7.5 N/cm2), MTPP(5.22 ± 2.64 N/cm2 to 23.3 ± 9.6 N/cm2). Initial high HFPP showed decline in subsequent follow-up and restored back to normal HFPP (36.91 ± 5.7 N/cm2 to 25.09 ± 3.7 N/cm2). Changes in pressures were statistically significant (< 0.001). Six patients had superficial wound infections healed with antibiotics. 23 patients who underwent a post-operative MRI showed a mean of 27 mm muscle thickness and 7.1 mm tendon thickness with complete incorporation of the FHL. ConclusionFoot peak pressures though initially deranged, are restored and comparable to normal foot after FHL transfer for chronic retracted TA tear. FHL hypertrophy is observed at the muscle thickness and at the distal tendon and provides adequate strength to repair and restore foot pressures. Level of evidence IIIProspective comparative study (normal versus operated foot).

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 evidenceIV.

Impact of Dual-Energy Computed Tomography (DECT) Postprocessing Protocols on Detection of Monosodium Urate (MSU) Deposits in Foot Tendons of Cadavers.

To evaluate two different dual-energy computed tomography (DECT) post-processing protocols for the detection of MSU deposits in foot tendons of cadavers with verification by polarizing light microscopy as the gold standard. A total of 40 embalmed cadavers (15 male; 25 female; median age, 82 years; mean, 80 years; range, 52-99; SD ± 10.9) underwent DECT to assess MSU deposits in foot tendons. Two postprocessing DECT protocols with different Hounsfield unit (HU) thresholds, 150/500 (=established) versus 120/500 (=modified). HU were applied to dual source acquisition with 80 kV for tube A and 140 kV for tube B. Six fresh cadavers (4 male; 2 female; median age, 78; mean, 78.5; range 61-95) were examined by DECT. Tendon dissection of 2/6 fresh cadavers with positive DECT 120 and negative DECT 150 studies were used to verify MSU deposits by polarizing light microscopy. The tibialis anterior tendon was found positive in 57.5%/100% (DECT 150/120), the peroneus tendon in 35%/100%, the achilles tendon in 25%/90%, the flexor halluces longus tendon in 10%/100%, and the tibialis posterior tendon in 12.5%/97.5%. DECT 120 resulted in increased tendon MSU deposit detection, when DECT 150 was negative, with an overall agreement between DECT 150 and DECT 120 of 80% (p = 0.013). Polarizing light microscope confirmed MSU deposits detected only by DECT 120 in the tibialis anterior, the achilles, the flexor halluces longus, and the peroneal tendons. The DECT 120 protocol showed a higher sensitivity when compared to DECT 150.

Flexor hallucis longus tendon morphology in dancers clinically diagnosed with tendinopathy.

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. 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. 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. 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.

Minimally invasive surgeries for insertional Achilles tendinopathy: A commentary review.

Studies of minimally invasive surgery for insertional Achilles tendinopathy are limited. To establish this surgery, the following techniques must be minimally invasive: Exostosis resection at the Achilles tendon insertion, debridement of degenerated Achilles tendon, reattachment using anchors or augmentation using flexor hallucis longus (FHL) tendon transfer, and excision of the posterosuperior calcaneal prominence. Studies on these four perspectives were reviewed to establish minimally invasive surgery for insertional Achilles tendinopathy. Techniques for exostosis resection were demonstrated in one case study, where blunt dissection around the exostosis was performed, and the exostosis was resected using an abrasion burr under fluoroscopic guidance. Techniques for debridement of degenerated Achilles tendon were demonstrated in the same case study, where the space left after resection of the exostosis was used as an endoscopic working space, and the degenerated Achilles tendon and intra-tendinous calcification were debrided endoscopically. Achilles tendon reattachment techniques using suture anchors have been demonstrated in several studies. However, there are no studies on FHL tendon transfer techniques for Achilles tendon reattachment. In contrast, endoscopic posterosuperior calcaneal prominence resection is already established. Additionally, studies on ultrasound-guided surgeries and percutaneous dorsal wedge calcaneal osteotomy as minimally invasive surgery were reviewed.

Endoscopically Assisted Percutaneous Harvesting of the Flexor Hallucis Tendon in Zone 2: An Anatomical Study.

Flexor hallucis longus (FHL) transfer is a well-established method for treating chronic Achilles tendon ruptures and tendinopathy. Harvesting of the FHL tendon in zone 2 results in greater length but is also associated with an increased risk of injury to the medial plantar nerve and requires an additional plantar incision. Because of the anatomic proximity of the FHL tendon to the tibial neurovascular bundle in zone 2, the purpose of this study was to investigate the risk of vascular or nerve injury with arthroscopic assisted percutaneous tenotomy in zone 2 of the FHL tendon. Endoscopically assisted percutaneous FHL transfer was performed on 10 right lower extremities from 10 cadaveric human specimens. The FHL tendon lengths and the relationship between FHL tendon and the tibial neurovascular bundle at zone 2 was analyzed. We observed a complete transection of the medial plantar nerve in 1 case (10%). The mean length of the FHL tendon was 54.7 ± 9.5 mm and the mean distance from the distal stump of the FHL tendon to local neurovascular structures was 1.3 ± 0.7 mm. There is a risk of neurovascular injury after endoscopic FHL tenotomy in zone 2. The tenotomy site is within 2 mm of the local neurovascular structures in the majority of cases. The additional length gained from this technique is unlikely to be required for the majority of FHL tendon transfer procedures. If additional length is needed, we would recommend the use of intraoperative ultrasonography or a mini-open approach to minimize injury risk. Level V, expert opinion.

Transfer of the Flexor Hallucis Longus Tendon for Neglected and Degenerative Tendo Achillis Rupture: A Prospective Clinical Study

Transfer of the Flexor Hallucis Longus Tendon for Neglected and Degenerative Tendo Achillis Rupture: A Prospective Clinical Study