A Review of Extensor Hallucis Longus Variants Featuring a Novel Extensor Primi Internodii Hallucis Muscle Merging With Extensor Hallucis Brevis

The extensor hallucis longus (EHL) muscle/tendon complex has been used in a variety of tendon transfer and tenodesis surgeries to correct iatrogenic hallux varus deformity, equinovarus foot deformity, clawed hallux associated with a cavus foot, and dynamic hyperextension of the hallux and, even, to prevent pedal imbalance after transmetatarsal amputation. Although it is usually considered a unipennate muscle inserting into the dorsum of the base of the distal phalanx of the hallux, a vast majority of EHL muscles possess ≥1 accessory tendinous slips that insert into other neighboring bones, muscles, or tendons, which can complicate these surgeries. The present report reviewed the reported data on EHL variants and describe a new variant, in which the tendons of the extensor primi internodii hallucis muscle of Wood and extensor hallucis brevis muscle merged together proximal to the tarsometatarsal (Lisfranc) joint, a site of rupture for extensor tendons of the foot. The reported variant might have contributed to the development of the clawed hallux seen in our patient and could complicate its operative management by mimicking the normal extensor digitorum longus tendon. Knowledge of the EHL variants and the particular muscular pattern described in the present review could improve the diagnosis and tendon transfer and tenodesis operative planning and outcomes.     

Anatomical Study of the Accessory Tendon of the Extensor Hallucis Longus Muscle and Its Clinical Application

BackgroudThe accessory tendon of the extensor hallucis longus (ATEHL) muscle is a common abnormal structure, and its clinical significance remains debatable. In this study, we provide the incidence of the ATEHL and characterize its morphological types in Asian cadavers and investigate its clinical applications.MethodsThe tendons from 50 adult cadaveric feet, fixed in 10% formalin, were analyzed. We measured the length and width of both the ATEHL and the extensor hallucis brevis (EHB).ResultsAll dissected specimens had an ATEHL. The first metatarsophalangeal joint was surrounded by an accessory tendon that inserted onto the joint capsule and the dorsal base of the proximal phalanx. We classified the ATEHL into 3 types based on their directions. Differences in ATEHL type based on sex were not statistically significant.ConclusionsWe found an ATEHL in all cadaveric specimens in this study. We surmise that the ATEHL acts as an antagonist with the EHB when the toe is extending, which might help prevent the occurrence of hallux valgus deformity.     

The extensor hallucis capsularis tendon – A prospective study of its occurrence and function

BackgroundThere is inhomogeneous data about the hallucal extensor apparatus and the occurrence of accessory tendon slips and their function. We performed this study to clarify its anatomical features and make conclusions about its function.MethodsInvestigations were performed prospectively during operative correction of severe hallux valgus and interphalangeus in 60 consecutive cases. The occurrence, topographic location and size of accessory extensor tendons as well as the insertion patterns were recorded. After dissection traction of the accessory tendon was carried out to gain information about its function.ResultsIn contradiction to previous studies reporting numerous variations in the distal attachments of the hallucal extensor apparatus with different accessory tendons described, our investigations showed constant anatomical features. In all but one case (98.3%) there was an accessory medial extensor hallucis longus tendon adjacent to the main tendon, always inserting on the dorsomedial aspect of the metatarsophalangeal joint capsule. We therefore chose the terminology extensor hallucis capsularis (EHC) used in previous studies. The intraoperative testing of the tendon showed it to exert a pretension of the metatarsophalangeal (MTP) joint capsule.ConclusionOur study showed consistent anatomical features with an occurrence of the EHC tendon in 98.3%. We determined that its function is to pretension the MTP joint capsule, therefore avoiding capsular impingement during hallucal extension. The high incidence of the EHC tendon in our study may also postulate a correlation with MTP joint deformities and further cadaveric studies will be necessary to evaluate a possible predisposition for hallux valgus genesis.     

Checkrein deformity due to extensor hallucis longus hypotrophy treated with extensor digitorum longus tendon transfer

Checkrein deformity is a relatively rare condition caused by hypotrophy or adhesion of a tendon after a lower leg injury. The occurrence of this condition due to the dysfunction of the extensor hallucis longus (EHL) is extremely rare. Only a few related case reports have been published, and Z-lengthening of the EHL tendon was performed for almost all patients.We report a case of checkrein deformity due to EHL hypotrophy. The patient was involved in a traffic accident 7 years ago. He sustained left tibial and fibular closed diaphyseal fractures and underwent minimally invasive plate osteosynthesis. He continued to have left great toe symptoms characterized by dorsiflexion of the great toe during ankle plantarflexion. The EHL had become an insufficient power source because of considerable hypotrophy. Therefore, a tendon transfer using the extensor digitorum longus to the second toe was performed as a primary treatment.     

Technique tip: EDL-to-EHL double loop transfer for extensor hallucis longus reconstruction

BackgroundExtensor hallucis longus (EHL) tendon injuries often occur in the setting of lacerations to the dorsum of the foot. End-to-end repair is advocated in acute lacerations, or in chronic cases when the tendon edges are suitable for tension free repair. Reconstruction with allograft or autograft is advocated for cases not amenable to a primary direct repair. This is often seen in cases with tendon retraction and more commonly in the chronic setting. In many countries the use of allograft is very limited or unavailable making reconstruction with autograft and tendon transfers the primary choice of treatment. Tendon diameter mismatch and diminished resistance are common issues in other previously described tendon transfers.MethodsWe present the results of a new technique for reconstruction of non-reparable EHL lacerations in three patients using a dynamic double loop transfer of the extensor digitorum longus (EDL) of the second toe that addresses these issues.ResultsAt one-year follow up, all patients recovered active/passive hallux extension with good functional (AOFAS Score) and satisfaction results. No reruptures or other complications were reported in this group of patients. No second toe deformities or dysfunction were reported.ConclusionsSecond EDL-to-EHL Double Loop Transfer for Extensor Hallucis Longus reconstruction is a safe, reproducible and low-cost technique to address EHL ruptures when primary repair is not possible.Level of evidenceIV (Case Series).     

Post-surgical hallux varus. A case report

Sometimes a hallux varus occurs as a consequence of the treatment for a hallux valgus, determined by an alteration of the balance between the muscolo-ligamentous structure which crosses the first metatarso-phalangeal joint. This complication is poorly tolerated by patients. Various operations have been proposed to correct the varus, which includes the bone and the soft tissue. A clinical case has been presented which uses a split extensor hallucis longus transfer, distally sectioned and made to pass under the deep transverse intermetatarsal ligament, used as a pulley, and through a tunnel made in the bone at the proximal-lateral base of the proximal phalanx, and then tensioned and sutured to its medial side.     

Arthroscopically assisted Z-lengthening of extensor hallucis longus tendon

Extensor hallucis longus tendon contracture can lead to hyperextension deformity of the big toe. We describe an endoscopic approach of Z-lengthening of the tendon. Extensor hallucis longus tendoscopy is performed with a distal portal at the level of the metatarsal neck and a proximal portal at the level of the navicular. At the distal portal, the medial half of the extensor hallucis longus tendon is cut and a stay stitch of No. 2 ethibond is applied. It is then stripped proximally with a tendon stripper to the proximal portal. A stay stitch of No. 2 ethibond is applied to the lateral half of the tendon at the proximal portal and it is cut proximal to the stitch. With the ankle plantarflexed and the big toe kept in the similar position as the lesser toes, the tendon segments are kept in tension through the stay stitches via the proximal and distal portals. The stay stitches of distal tendon segment are sutured to the proximal segment at the same level of the cut end of the distal fragment with the aid of an eyed needle under arthroscopic visualization through the distal portal. The needle is passed through the tendon and then the skin. The suture is also passed through the skin and then retrieved to the proximal portal by a hemostat. It is then sutured to the proximal tendon segment at the proximal portal. Similarly, the proximal tendon end is sutured to the distal tendon segment at the corresponding level and the endoscopic Z-lengthening of the extensor hallucis longus tendon is then completed.     

A Combined Surgical Approach for Extensor Hallucis Longus Reconstruction: Two Case Reports

The surgical management of foot tendon injuries is not well-represented in literature. To achieve excellent functional recovery of the extensor hallucis longus (EHL) tendon, we aimed at developing a reliable and feasible reconstructive technique.A surgical technique for delayed reconstruction of the EHL tendon, combining an elongation procedure with second toe extensor tendon transfer, is described in this article.The results of this combined approach for EHL tendon reconstruction were remarkable, since the patients of the two clinical cases reported regained active extension of the hallux after 6 months without any associated complication.This study represents a step forward in foot surgery, since it describes an alternative technique to manage EHL tendon lesions.     

(足母)长伸肌腱移位动力性矫正(足母)外翻畸形

目的探讨长伸肌腱移位动力矫正外翻畸形的机制及临床疗效。方法2004年4月～2006年12月,采用长伸肌腱移位矫治外翻畸形25例38足。其中男2例3足,女23例35足;年龄22～60岁,平均46.3岁。术前外翻角21～45°,平均31.30°;跖间角7～21°,平均12.52°。手术将第1跖骨骨赘凿除,内侧关节囊修复,收肌横头切断,长伸肌腱向内侧移位、止点再造。结果术后外翻角7.30±2.62°,跖间角6.50±2.46°,与术前比较差异均有统计学意义(P<0.05)。术后功能应用美国足踝外科协会趾-跖趾-趾间关节评分系统进行临床评估,优25足,良7足,差6足,优良率84.2%。获随访6～24个月。2足于术后2个月出现内翻,2足术后3个月出现第1跖趾关节活动受限。无外翻畸形复发。结论通过口止母长伸肌腱内移等软组织平衡恢复了第1跖趾关节内、外侧应力,手术操作简便,畸形矫正效果好且不易复发。     

Split Peroneus Longus Free Tendon Autograft Transplantation for the Treatment of Neglected Extensor Hallucis Longus Tendon Laceration: A Case Report

A neglected laceration of the extensor hallucis longus (EHL) tendon is rare. Retraction of the tendon ends often occurs when a laceration is neglected, leading to a substantial tendon deficit. A paucity of case reports is available describing the treatment of EHL laceration with a large area of gap secondary to retraction. Therefore, the treatment recommendations are limited. We present the case of a neglected EHL tendon laceration with a 10.5-cm gap in a healthy 22-year-old female. The EHL tendon laceration was repaired using a split peroneus longus tendon autograft that, to the best of our knowledge, has not been previously reported. At the 3-year follow-up evaluation, the patient retained full function of her hallux and was free of symptoms.     

Surgical Correction of Checkrein Deformity after Malunited Distal Tibia Fracture: A Case Report

Checkrein deformities are rare and involve entrapment or tethering of the flexor hallucis longus and, occasionally, flexor digitorum longus tendons. The deformity has typically been secondary to traumatic fractures of the talus, calcaneus, or deep posterior compartment syndrome resulting from fractures of the tibia and fibula and most fractures of the ankle. These result in flexion contractures at the interphalangeal joint of the hallux. Because of the rarity of this deformity, no single surgical technique has been defined as the standard. Previous interventions have included release of adhesions with or without Z-plasty lengthening of the involved tendons. The present study reports a case of checkrein deformity secondary to a malunited distal tibia fracture, with flexion deformities to digits 1 through 3. The patient underwent successful surgical correction with flexor tenotomies to the affected digits with interphalangeal arthrodesis to the hallux.     

Alternative to the modified jones procedure: outcomes of the flexor hallucis longus (FHL) tendon transfer procedure for correction of clawed hallux

BACKGROUND: The modified Jones procedure is the traditional operative procedure for correction of a clawed hallux, although the deformity may be caused by overpull of one of three different muscles. In this study we present the radiographic and functional outcomes of flexor hallucis longus (FHL) tendon transfer as treatment for clawed hallux. The transfer is performed by drawing two thirds of the FHL tendon up through a drill hole in the proximal phalanx and then suturing it medially back to the remaining third. METHODS: We retrospectively identified 19 patients (22 feet) who had FHL tendon transfer for correction of clawed hallux over a period of 5 years. Followup was an average of 51.0 (range 6 to 74; +/- 3.8) months after the procedure. Outcome and patient satisfaction were determined using the Long-Form Musculoskeletal Function Assessment (MFA) score. Patients were asked whether they were satisfied, somewhat satisfied, or dissatisfied with the overall outcome and were asked about shoewear limitations. Preoperative and postoperative radiographs were evaluated in 15 patients (17 feet). We measured the hallux valgus and interphalangeal (IP) angles on the anteroposterior (AP) radiographs. On the lateral view we measured the angle of the IP joint, the metatarsophalangeal (MTP) joint, and the talometatarsal angle. Statistical analysis was done using a repeated measures ANOVA (p < 0.05). RESULTS: On the lateral radiographs, the hallux IP joint angle (p < 0.0012; n = 15) and hallux MTP joint angle (p < 0.0265; n = 15) were significantly reduced postoperatively. On AP radiographs, the hallux valgus angle (p < 0.0334) was significantly reduced; however, the IP angle and the talometatarsal angle were not significantly different after surgery. Patients had an average MFA score of 14.6 (+/-3.8 standard error, range 1 to 35; n = 19). Thirteen patients were fully satisfied and six were somewhat satisfied with the overall result of the surgery. Four patients thought that their hallux limited the types of shoes they could wear, while 15 did not. CONCLUSION: It has been shown that clawed hallux can result from excessive motor function in one of three muscles: FHL tendon, peroneus longus (PL), and extensor hallucis longus (EHL). This study suggests that transfer of part of the tendon of the FHL is an effective alternative operative procedure for correction of clawed hallux.     

Muscular activity and torque of the foot dorsiflexor muscles during decremental isometric test: A cross-sectional study

PurposeTo analyse the torque variation level that could be explained by the muscle activation (EMG) amplitude of the three major foot dorsiflexor muscles (tibialis anterior (TA), extensor digitorum longus (EDL), extensor hallucis longus (EHL)) during isometric foot dorsiflexion at different intensities.MethodsIn a cross-sectional study, forty-one subjects performed foot dorsiflexion at 100%, 75%, 50% and 25% of maximal voluntary contractions (MVC) with the hip and knee flexed 90° and the ankle in neutral position (90° between leg and foot). Three foot dorsiflexions were performed for each intensity. Outcome variables were: maximum (100% MVC) and relative torque (75%, 50%, 25% MVC), maximum and relative EMG amplitude. A linear regression analysis was calculated for each intensity of the isometric foot dorsiflexion.ResultsThe degree of torque variation (dependent variable) from the independent variables explain (EMG amplitude of the three major foot dorsiflexor muscles) the increases when the foot dorsiflexion intensity is increased, with values of R² that range from 0.194 (during 25% MVC) to 0.753 (during 100% MVC). The reliability of the outcome variables was excellent.ConclusionThe EMG amplitude of the three main foot dorsiflexors exhibited more variance in the dependent variable (torque) when foot dorsiflexion intensity increases.     

Flexor hallucis longus tendon transfer for hallux claw toe deformity and vertical instability of the metatarsophalangeal joint

BACKGROUND: Historically, operative treatment of hallux claw toe deformity has been the Jones procedure or one of its modifications. Review of the literature confirms its ability to maintain alignment and achieve patient satisfaction; however, several complications have been reported. Many of these are related to altered biomechanics across the metatarsophalangeal (MTP) joint. A similar approach to this clinical problem involves restoration of the flexion moment across the MTP joint without an interphalangeal (IP) joint arthrodesis. METHODS: We conducted a retrospective review of 10 patients who had a flexor hallucis longus (FHL) tendon transfer to the proximal phalanx of the great toe for hallux claw toe deformity, as well as for symptomatic vertical instability. Four patients had a positive drawer test indicating vertical instability without static deformity. Two patients with vertical instability were found to have a dynamic deformity. Mean followup was 24 (SD 15.2) months. RESULTS: All deformities were corrected and alignment was maintained at the time of followup. Pain under the first metatarsal head was reliably improved in symptomatic patients (p < 0.05). Patient satisfaction also was assessed. All six patients treated for hallux claw deformity were satisfied with their outcomes. Two of the four patients treated for vertical instability were satisfied. The other two patients expressed dissatisfaction because of persistent pain that occurred during strenuous exercise. Their symptoms during routine activity were improved, however. CONCLUSION: Based on initial results, the FHL transfer to the proximal phalanx appears to be a viable treatment option for hallux claw deformity in terms of deformity correction, pain relief, and patient satisfaction. Further evaluation is warranted regarding the indication of vertical instability.     

Dynamic Positional Deformity of the Hallux

The present study reports a case with concomitant tethering of the flexor tendon and extensor tendon of the hallux after closed tibiofibular shaft fractures. We have obtained good clinical results using tenotomy of the flexor hallucis longus tendon and Z-plasty lengthening of the extensor hallucis longus tendon. Because few studies have described the clinical results and operative methods for this type of combined deformity, we report a case with dynamic positional deformity of the hallux.     

Minimal incision tenotomy for hallux interphalangeal joint extensus

The spoon-toe hallux deformity causing symptomatic hallux pathology can be corrected through a minimal incision stab tenotomy of the extensor hallucis longus tendon that is usually performed at the level of the interphalangeal joint. This procedure is recommended rather than a traditional tenoplasty because it creates very little disability, successfully reduces the deformity, has low incidence of complications, and produces lasting results in maintaining the correction. The procedure can be used as both a solo procedure or in conjunction with other procedures on the hallux.     

Correction of clawed hallux deformity: comparison of the Jones procedure and FHL transfer in a cadaver model

BACKGROUND: A clawed hallux is defined as extension of the first metatarsophalangeal (MTP) joint combined with flexion of the interphalangeal (IP) joint. Two operative procedures, the modified Jones procedure and flexor hallucis longus (FHL) transfer, are indicated for correction. The purpose of this study were to evaluate the overall effectiveness of these two procedures in correcting both the clawed hallux deformity and its mechanical consequences and to compare their effect on postoperative plantar pressures. METHODS: The modified Jones procedure and FHL transfer were done on cadaver specimens that were tested before and after surgery in a specialized foot-loading frame. We quantified the angular correction of the MTP and the IP joints, as well as the plantar pressures under the head of the first metatarsal and the hallux. RESULTS: Both surgeries were equally effective in correcting the angular deformity at the MTP and IP joints (p = 0.037 and 0.0020, respectively). A significant reduction in the plantar pressure (p = 0.015) beneath the first metatarsal was observed with both the modified Jones procedure and the FHL transfer. Overall, there was no significant difference between preoperative and postoperative pressures beneath the hallux (p = 0.5); however, for the FHL overpull group there was significantly less pressure beneath the hallux after surgery (p = 0.014). CONCLUSIONS: The two surgeries produced similar results, but the FHL transfer does not require fusion of the hallux, which is considered an undesirable co-morbidity of the modified Jones procedure.     

胫骨骨折髓内钉固定术后屈趾畸形(附5例临床分析)

目的探讨胫骨骨折髓内钉固定术后屈趾畸形的发生机制及防治措施。方法362例胫骨骨折患者施行髓内钉固定手术,其中5例(1.4%)术后出现屈趾畸形,其临床表现为跛行、踝关节中立位足趾屈曲畸形,背伸时畸形加重,跖屈位畸形减轻。保守治疗无效,均行拇长屈肌及趾长屈肌肌腱"Z"形延长术。结果5例术后平均随访19.7(16~24)月。术后患者中立位足趾屈曲畸形消失,步态均恢复正常,踝关节背伸时足趾轻度屈曲畸形。拇长屈肌及趾长屈肌肌力5级。结论胫骨骨折髓内钉固定术后足趾屈曲畸形为少见并发症,其发生可能与术前拇长屈肌及趾长屈肌的损伤未得到有效治疗,术中髓内钉导针、扩髓器对拇长屈肌、趾长屈肌的损伤或术后小腿深后骨筋膜鞘内压力增高引起的肌肉缺血、纤维化改变有关;肌腱延长术是有效的治疗方法。     

Muscular imbalances resulting in a clawed hallux

A clawed hallux is a deformity of the great toe resulting from a muscular imbalance. Using a cadaveric foot-loading frame, we quantitatively assessed the role of the peroneus longus (PL), extensor hallucis longus (EHL), and flexor hallucis longus (FHL) on position and pressure distribution of the first ray by simulating muscle imbalances. The experimental protocol included applying seven different combinations of simulated disproportionate loads ("overpulls") for these three muscles using midstance force values derived from the literature. This study quantified the angular change in the joints of the first ray and measured the plantar pressure beneath the head of the first metatarsal and the hallux. The results indicated that the peroneus longus was statistically the greatest contributor to the elevation of plantar pressure beneath the first metatarsal, while the EHL and FHL were primarily responsible for the angular changes resulting in the clawed hallux deformity.     

Obtaining Adequate Tension for Extensor Hallucis Longus Tendon Rupture Repair Using Wide-Awake Surgery: A Case Report

Wide-awake surgery has potential advantages for treating extensor or flexor tendon injury. We present a case of chronic extensor hallucis longus injury treated with turn-down reconstruction using wide-awake surgery with a selective nerve block. To the best of our knowledge, this is the first such case reported. The patient had dropped a knife proximal to the right hallux metatarsophalangeal joint. Because direct suturing was thought to be difficult, turn-down reconstruction was performed under a selective nerve block. At 8 months postoperatively, the hallux had 75° of extension in the metatarsophalangeal joint and ?5° of extension in the interphalangeal joint, similar to those of the healthy foot. The Japanese Society for Surgery of the foot objective hallux scale score had improved from 87 to 100, and the subjective scores in the subcategories of pain and pain-related, physical functioning and daily living, and shoe-related in the self-administered foot evaluation questionnaire had improved from 82.8 to 94.4, 97.7 to 100, and 50 to 83.3, respectively. Turn-down reconstruction using wide-awake surgery with a selective nerve block can be used for chronic extensor hallucis longus rupture and can be expected to provide good results.