Pressure changes in the medial and lateral plantar and tarsal tunnels related to ankle position: a cadaver study

BACKGROUND: Pressure in the tarsal tunnel has been shown to be elevated when the ankle is pronated. We hypothesized that this also would be true for the medial plantar and lateral plantar tunnels because they also are potential sites of nerve compression. Additionally, we hypothesized that decompression surgery, including a release of the superficial and deep fascia of the abductor hallucis muscle and excision of the septum between the medial and lateral plantar tunnels, would decrease the pressure in all three tunnels. METHODS: Twelve fresh cadaver legs were obtained, and pressure measurements were made in a variety of ankle positions in the tarsal and medial and lateral plantar tunnels before and after decompression surgery. For the medial and lateral plantar tunnels, pressures were obtained after tunnel roof (deep fascia of the abductor hallucis) incision and after both roof incision and excision of the septum between the two tunnels. RESULTS: Pressures were significantly elevated in all tunnels with ankle pronation, were significantly decreased in all positions in the tarsal tunnel after decompression, and significantly decreased in most positions in the medial and lateral plantar tunnels after decompression. Septum excision led to additional significant decreases in pressure in some positions. CONCLUSIONS: Pressures within the medial and lateral plantar tunnels and the tarsal tunnel increase significantly with changes in ankle subtalar position. These pressure changes can be significantly decreased by operative release of each of these three tunnels, including excision of the septum between the medial and lateral plantar tunnels. CLINICAL RELEVANCE: Symptoms related to chronic compression of the tibial nerve and its branches at the ankle may be relieved by an operative strategy that targets release of multiple anatomic regions of tightness in the medial ankle rather than focusing on the tarsal tunnel alone.     

Tarsal tunnel syndrome. Nerve compression syndrome in the foot

Pathological changes in sensation over the sole of the foot do not always correspond to the full area of distribution of the posterior tibial nerve. Some neurologists advise separate examination of the tibial nerve, the medial and lateral plantar nerves, in order to ascertain whether either or both might be affected. 60 preparations of cadaveric feet in the Department of Anatomy were examined. Using a measuring grid, the position and size of the nerves in the tarsal tunnel were assessed and the facial band which define and divide the osteofibrous canal delineated. The corners of the measuring grid were the tip of the medial malleolus (A), the tip of the calcaneal tubercle at its greatest distance from the medial malleolus (B) and the tuberosity of the navicular bone (C). These points can also be clearly identified clinically. They define a triangle whose sides A-B and B-C are of constant equal length and whose base A-C varies little. The operative approach includes a T-shaped incision of the retinaculum. The vertical line of the T lies underneath the skin incision. The horizontal line corresponds with the upper border of the abductor hallucis muscle. The upper border of the abductor hallucis is defined and the muscle retracted medially to expose the deep fascia. This layer is removed together with the connective tissue bridge which stretches between the fascia and the calcaneus. The plantar nerves are discovered and run to the sole of the foot without further obstruction.     

Distally based abductor hallucis muscle flap: anatomic basis and clinical application

Although rarely used, the abductor hallucis muscle has its indications in coverage of small defects at the medial aspect of the hindfoot as a proximally based muscle flap. The authors describe a 69-year-old female patient in whom the abductor hallucis muscle was used as a distally based flap to reconstruct a defect in the forefoot. An anatomic study was undertaken on two cadaveric feet to explore the practicality of the distally based abductor hallucis muscle flap before it was applied clinically. The distally based abductor muscle flap receives its blood supply from minor and major pedicles in a retrograde fashion from both the dorsal arterial network and the deep plantar system, through communicating branches with the medial plantar artery distally. Transposition of the distally based hallucis flap is only advisable in individuals who have no vascular compromise in the lower leg and foot. To the authors' knowledge, this modification has not yet been described in the available literature.     

Avulsion fracture of the calcaneus at the origin of the abductor hallucis muscle

Previously reported avulsion fractures of the calcaneus have been confined to the attachment of the tendo achillis, bifurcate ligament, extensor digitorum brevis muscle, or the plantar fascia. A case report of a previously undescribed avulsion fracture of the calcaneus due to the abductor hallucis muscle is presented. The mechanism of injury, forced dorsiflexion of the forefoot, is described. A diagnostic and treatment regimen is provided. With appropriate identification of the injury, this unusual calcaneal fracture can be adequately managed.     

Residual adduction of the forefoot. A review of the Turco procedure for congenital club foot

Forty-four feet in 28 children previously treated by a one-stage posteromedial release operation (the Turco procedure) were reviewed clinically and radiologically to determine the cause of residual adduction of the forefoot. In 21 clinically adducted feet (48%) the main cause of residual deformity was metatarsus varus alone or metatarsus varus in spite of talonavicular overcorrection; in five feet the cause was talonavicular subluxation. There was no residual adduction in 23 feet (52%) but only 12 had normal radiographic measurements. In the remaining feet, various forms of spurious correction of metatarsus varus and talonavicular subluxation or both were seen, resulting in normal-looking feet. Recession of the origin of abductor hallucis and release of the short plantar muscles and fascia at the time of posteromedial release is recommended. The forefoot adduction was satisfactorily corrected in 91% of the feet subsequently operated on using this modified procedure.     

An analysis of the results of a modified one-stage posteromedial release (Turco operation) for the treatment of clubfoot

Between 1971 and 1977, posteromedial release was performed on 47 feet of 30 children 9 months to 4 years of age. At review, full correction of equinus was achieved in 98%, heel varus in 91%, and cavus in 85%, but in only 50% of feet with forefoot adduction. Between 1978 and 1982, surgery was performed on 22 feet of 18 children 3-10 months of age. Recessions of the abductor hallucis and short plantar muscles and fascia were also performed at operation. Correction of equinus, heel varus, and cavus demonstrated results similar to those of the earlier group, but forefoot adduction was also satisfactorily corrected in 91% of feet.     

Vascular anatomy of plantar muscles

Many reports on the plantar arteries and the deep plantar arch exist, but none of them focus on the arterial pedicles of the plantar muscles. They mainly discuss the deep plantar arch, its variations, and location. This study plans to determine the location and origin of arterial pedicles of all the plantar muscles as a preliminary study for designing new flaps. The study was carried out on 20 feet from 10 cadavers aged from 35 to 67 years. After an injection of latex via popliteal arteries, dissection of the arteries was carried out under a microscope. Abductor hallucis and flexor hallucis brevis muscles receive their main blood supply from the medial plantar artery; abductor digiti minimi and flexor digiti minimi brevis muscles receive their main blood supply from the lateral plantar artery. The flexor digitorum brevis muscle receives branches from both arteries. Adductor hallucis and plantar interosseous muscles receive branches from plantar metatarsal arteries. Quadratus plantae is directly nourished from a branch of the posterior tibial artery. No distal anastomoses between the medial and lateral plantar arteries were identified, except 1 specimen in which the medial plantar artery made anastomosis with the deep plantar arch. As a result, the arterial pedicles of all the plantar muscles were defined, and based on these findings, new flaps can be planned or existing flaps can be modified.     

Innervation of three weight-bearing areas of the foot: an anatomic study and clinical implications.

The aim of this cadaver study is to improve our knowledge on the anatomy of the sensory fibres of the three weight-bearing areas of the plantar region. Previous studies mainly focused on the innervation of the heel but the innervation of the other two weight-bearing areas over the most medial and lateral metatarses have been neglected and are not well known. The study was carried out on 10 feet of five male cadavers. The tibial nerve was dissected down to the fat pads over the heel and the first and fifth metatarsal heads under the microscope. The distances of the branching point of the tibial nerve and origins of the medial and inferior calcaneal nerves to a line drawn from the centre of the medial malleolus to the centre of the calcaneous were all measured. The tibial nerve was divided into two branches called the lateral and medial plantar nerves 23.45 mm proximal to the predefined axis. The medial plantar nerve passed underneath the abductor hallucis muscle and gave two sensory branches to the fat pad over the first metatarsal head. The lateral plantar nerve coursed beneath the abductor hallucis and flexor digitorum brevis muscles and supplied innervation of the fat pad over the fifth metatarsal head. The sensory innervation of the heel was provided by medial calcaneal and inferior calcaneal nerves. The medial calcaneal nerve originated from the tibial nerve 41.89 mm proximal to the axis. It divided into two or three branches innervating the fat pad over the heel. The inferior calcaneal nerve originated from the lateral plantar nerve (70%) or the medial calcaneal nerve (30%) 10.66 mm proximal to the axis. This study describes the sensory fibres to the heel and the previously neglected weight-bearing areas over the first and fifth metatarses. Reconstruction of defects in these areas is very difficult so every attempt should be made to protect the sensory fibres during any surgical procedure.     

吻合血管的足内侧穿支皮瓣的应用解剖与临床应用

目的 研究足内侧穿支皮瓣的应用解剖及修复手部软组织缺损的临床效果.方法 10侧成人足踝标本经胴动脉注入红色乳胶液,解剖观测足底内侧动脉穿支血管在足内侧区的分布、起源等.临床设计吻合血管的足内侧穿支皮瓣修复手部软组织缺损11例,软组织缺损面积2 cm×2 cm～9cm×4 cm.结果 足底内侧动脉向<足母>展肌和趾短屈肌肌间隙内发出2支相对恒定的足底内侧皮穿支,供养足底内侧皮瓣;向<足母>展肌和舟楔骨间隙内发出2支相对恒定的足内侧皮穿支,供养足内侧皮瓣.11例足内侧穿支皮瓣完全成活,皮瓣面积2 cm×3 cm～11 cm×5 cm.随访6～24个月,皮瓣质地优良,外形与功能恢复满意,供区愈合良好.结论 以足内侧穿支血管营养的足内侧穿支皮瓣血供可靠,质地优良,是修复手部软组织缺损的良好选择.     

Tarsal tunnel syndrome

The natural history, diagnosis, and therapy of tarsal tunnel syndrome are given. Anatomical studies corresponding to the clinical picture and electrodiagnostic findings show two different narrow points in tarsal tunnel. Operative treatment should take into account the compression of the posterior tibial nerve by the flexor retinaculum and also of the plantar nerves under the abductor hallucis.     

Percutaneous Plantar Fascia Release With Needle: Anatomic Evaluation with Cadaveric Specimens

Percutaneous plantar fascia release with needle is a novel procedure for the treatment of plantar fasciitis. The objective of this cadaveric study is to perform an anatomic evaluation of the percutaneous plantar fascia release method using a conventional hypodermic needle. In this study, we used 14 fresh-frozen cadaveric trans-tibial amputation specimens. Percutaneous plantar fasciotomy with a conventional hypodermic needle was performed. After a proper dissection, the width of the plantar fascia, the thickness of the medial border, and the width of the cut segment were measured and recorded. Any muscle damage on the flexor digitorum brevis and damaged area depth were recorded. Any damage on the lateral plantar nerve and the first branch of the lateral plantar nerve, also known as Baxter's nerve, and their distance to fasciotomy were also recorded. Mean width (± standard deviation) of the plantar fascia was measured as 20.34 ± 4.25 mm. The mean thickness of the medial border of the plantar fascia was 3.04 ± 0.54 mm. Partial fasciotomy was performed in all cadavers with 49.47% ± 7.25% relative width of the plantar fascia. No lateral plantar nerve, or its first branch Baxter's nerve, was damaged, and the mean distance from the deepest point of the fasciotomy up to the Baxter's nerve was 8.62 ± 2.62 mm. This cadaveric study demonstrated that partial plantar fasciotomy can be achieved via percutaneous plantar fascia release with a conventional hypodermic needle without any nerve damage.     

Plantar Fascia Release Through a Single Lateral Incision in the Operative Management of a Cavovarus Foot: A Cadaver Model Analysis of the Operative Technique

Plantar fascia release and calcaneal slide osteotomy are often components of the surgical management for cavovarus deformities of the foot. In this setting, plantar fascia release has traditionally been performed through an incision over the medial calcaneal tuberosity, and the calcaneal osteotomy through a lateral incision. Two separate incisions can potentially increase the operative time and morbidity. The purpose of the present study was threefold: to describe the operative technique, use cadaveric dissection to analyze whether a full release of the plantar fascia was possible through the lateral incision, and examine the proximity of the medial neurovascular structures to both the plantar fascia release and calcaneal slide osteotomy when performed together. In our cadaveric dissections, we found that full release of the plantar fascia is possible through the lateral incision with no obvious damage to the medial neurovascular structures. We also found that the calcaneal branch of the tibial nerve reliably crossed the osteotomy in all specimens. We have concluded that both the plantar fascia release and the calcaneal osteotomy can be safely performed through a lateral incision, if care is taken when completing the calcaneal osteotomy to ensure that the medial neurovascular structures remain uninjured.     

Versatility of the abductor hallucis muscle as a conjoined or distally-based flap

Soft tissue coverage of the medial ankle and foot remains a difficult, challenging, and often frustrating problem to patients as well as surgeons. To our knowledge, the abductor hallucis muscle flap is not frequently used and only a few well documented cases were found in literature. The purpose of this paper is to report and to present the long-term results of a series of four patients who underwent reconstruction of foot and ankle defects with the abductor hallucis muscle flap.In two cases, the abductor hallucis muscle flap was transposed in combination with a medialis pedis flap to cover a medial ankle defect, whereas in another case it was combined with a medial plantar flap. In this latter case, the muscle flap served to fill up a calcaneal dead space after osteomyelitis debridement, whereas the cutaneous flap was used to replace debrided skin at the heel. The abductor hallucis flap was used as a distally-based turnover flap to cover a large forefoot defect in a fourth case. Follow-up period ranged between 18 and 64 months (mean 43.3). In the early postoperative period, two flaps healed completely In two patients marginal flap necrosis occurred which was subsequently skin grafted. No donor-site complication occurred in any of the patients. In all cases, protective sensation of the skin was satisfactory as early as 6 months. In two cases mild hyperkeratosis at the skin graft border to the sole skin (non-weight bearing area of medial plantar and medialis pedis flap donor site) was present, but probably related to poor foot care. All patients were fully mobile as early as 3 months after treatment. In the long-term follow-up (43.3 months), all flaps provided with durable coverage. Functional gait deficit due to consumtion of the abductor hallucis muscle was not apparent.Our long-term results demonstrated that the abductor hallucis muscle flap is a versatile, and reliable flap suitable for the reconstruction of foot and ankle defects. Utilizing the abductor hallucis muscle as a pedicled flap (distally or proximally-based) with or without conjoined regional fasciocutaneous flaps offers a successful and durable alternative to microsurgical tree flaps for small to moderate defects over the calcaneus region, medial ankle, medial foot, and forefoot with exposed bone, tendon, or joint.     

An anatomical study of tarsal tunnel

In order to understand the pathogenesis and improve the treatment of tarsal tunnel syndrome, we investigated the tarsal region anatomically on 62 feet of 31 cadavers and five freshly amputated feet. The following results were thus obtained: 1. The bifurcation into the medial and lateral plantar nerves mostly occurred within the flexor retinaculum. 2. The medial calcaneal branch showed many anatomical variations. 3. The flexor retinaculum was not clearly demarcated at its superior and inferior borders, and it was not as thick as previously thought. 4. The neurovascular bundle was separated from other tendon sheaths, and enclosed in its own tunnel. 5. A fibrous septum found at the entrance of the abductor hallucis muscle, may represent an entrapment point of the medial plantar nerve. 6. The ganglion from the talocalcaneal joint tended to compress only the medial plantar nerve.     

足内侧岛状皮瓣逆行转位修复足前部皮肤缺损的解剖与临床应用

目的 探讨足内侧岛状皮瓣逆行转位修复足前部皮肤缺损的术式.方法 48侧成尸足标本经动脉灌注红色乳胶,5侧新鲜足标本动脉造影,观测躅横动脉、第一跖底动脉、足底内侧动脉深支的外径、分布及其之间的吻合,并对躅趾底内侧动脉浅支进行分型,观察足内侧皮瓣内的动脉吻合和分布范围.临床上应用足内侧逆行岛状皮瓣修复足前部皮肤缺损12例,男11例,女1例;年龄12～54岁,平均32岁.皮肤缺损面积2.5 cm×3.5 cm～7.5 cm×9.5 cm.结果 <足母>横动脉与躅趾胫侧趾底固有动脉、<足母>趾腓侧趾底固有动脉、第一跖底动脉远侧段吻合形成动脉环.<足母>展肌上缘动脉弓和足底内侧动脉深支内侧支在<足母>展肌表面形成动脉网.临床上采用足内侧逆行岛状皮瓣修复足前部皮肤缺损12例均获得成功.皮瓣切取面积3 cm×4 cm～8 cm×10 cm.全部病例随访1～3年,平均2年,皮瓣全部成活,无破溃、臃肿,足、踝部功能正常,足部血供佳.结论 足内侧岛状皮瓣逆行转位修复足前部皮肤缺损,皮瓣旋转点最远可前移至<足母>趾近节趾中点,皮瓣切取面积大、血供好、手术方式简便、切取后对足部血供影响较小,是修复足前部皮肤缺损的理想皮瓣.     

Intrinsic pedal musculature support of the medial longitudinal arch: an electromyography study

Much of the work describing support of the medial longitudinal arch has focused on the plantar fascia and the extrinsic muscles. There is little research concerning the function of intrinsic muscles in the maintenance of the medial longitudinal arch. Ten healthy volunteer adults served as subjects for this study, which was approved by the University Investigational Review Board. The height of the navicular tubercle above the floor was measured in both feet while subjects were seated with the foot in a subtalar neutral position and then when standing in a relaxed calcaneal stance. Subtalar neutral was found by palpating for talar congruency. Recordings of muscle activity from the abductor hallucis muscle were performed while the subjects maintained a maximal voluntary contraction in a supine position by plantarflexing their great toes. An injection of lidocaine (1% with epinephrine) was then administered by a Board-certified orthopedic surgeon in the region of the tibial nerve, posterior and inferior to the medial malleolus. Measurements were repeated and compared by using a paired t test. After the nerve block, the muscle activity was 26.8% of the control condition (P = .011). This corresponded with an increase in navicular drop of 3.8 mm. (P = .022). The observation that navicular drop increased when the activity of the intrinsic muscles decreased indicates that the intrinsic pedal muscles play an important role in support of the medial longitudinal arch.     

Iatrogenic Damage to Neurovascular and Soft Tissue Structures During Lateral Release of Hallux Valgus: A Comparative Anatomical Study of Minimally Invasive Versus Open Surgical Techniques

Lateral release is often an integral step in surgical correction of hallux valgus and can be performed using open or minimally invasive techniques. We investigated whether these techniques cause iatrogenic damage to arteries, nerves, tendons, or joint capsules. In this cadaver study, lateral release was performed on 9 pairs of specimens by a specialized foot surgeon. The specimens were randomly assigned to each group. The operations were followed by anatomical preparation, data collection, photo documentation, and statistical analysis. Iatrogenic damage to arteries, nerves, tendons, or joint capsules was rare, regardless of the surgical technique used. However, with the minimally invasive technique, the tendon of the extensor hallucis longus muscle and the sensitive terminal branches of the fibular nerve were at risk due to their anatomical proximity to the access portal. The deep transverse metatarsal ligament was potentially at risk if the adductor hallucis muscle was completely detached from the lateral sesamoid. When the deep transverse metatarsal ligament was transected there was risk of damaging the underlying plantar neurovascular structures. Both surgical techniques are safe in terms of the risk of injury to neighboring neurovascular and soft tissue structures.     

Thomas Morton's disease: a nerve entrapment syndrome. A new surgical technique.

A new interpretation of the surgical treatment of Morton's neuroma consists of release of the anterior edge of the deep plantar fascia (deep intermetacarpal ligament) without resection of the neuroma. In 206 patients treated with this technique, 83% had rapid and stable improvement. An additional 15% were improved but with some persistence of pain. Division of the ligament without excision of the neuroma provides good pain relief in most patients without the hazards of loss of sensation, loss of sweat production, or neuroma development in the nerve stump.