Medial Dorsal Cutaneous Nerve Research Articles

Anatomic basis of the distally based venocutaneous flap on the medial plantar artery of the hallux with medial plantar vein and nutrient vessels: a cadaveric dissection.

This study aims to identify a repair procedure for ulcers or defect of the forefoot region. The general distribution and variation of the vascular anatomy of the distally based venocutaneous flap on the medial plantar artery of the hallux with medial plantar vein and nutrient vessels were investigated. This study especially focused on the vascularization of the medial side of the foot and the determination of the contribution of the nutrient vessels of medial plantar vein and medial dorsal cutaneous nerve to flap viability. Experiments were conducted to obtain information for operating procedures and to understand the vascular reliability of the flap. Thirty cadavers were available for this anatomical study after arterial injection. The tuberosity of the fifth metatarsal bone was adopted as the anatomical landmark. Microdissection was conducted under a microscope, and details of the course and distribution of the medial plantar vein and the communication of the medial plantar artery of the hallux with the fascial vascular network surrounding the medial plantar vein were recorded. The flap-raising procedure was performed in a fresh cadaver specimen. The medial plantar vein was incorporated by the medial end of the dorsal pedal vein arch and medial dorsal vein of the hallux around the first metatarsal-medial cuneiform joint. It traveled along the medial margin of the foot and drained into the great saphenous vein at the level of the medial malleolar. The outer diameter of the nerve at the intermalleolar line was 3.2 ± 0.5 mm. These nutrifying arteries to the medial plantar vein were present segmentally and mainly came from the medial plantar artery of the hallux, which traveled forward in the fascia between the abductor hallucis tendon and the first metatarsal bone, emerged into the superficial layer 2.2 ± 0.7 cm proximal to the first metatarsophalangeal joint, and gave off many minute branches. These branches communicated with the fascial vascular network surrounding the medial plantar vein, supplying the fascia and integument of the medial foot. Reliable venocutaneous flap with medial plantar vein and nutrient vessel flaps can be raised based solely on the perforator of the medial plantar artery of the hallux. This flap should be considered as a preferential way to reconstruct soft-tissue defects of the forefoot.

Neuroma of Medial Dorsal Cutaneous Nerve of Superficial Peroneal Nerve After Ankle Arthroscopy

Superficial peroneal neuropathy is a known complication of foot and ankle arthroscopy. A 27-year-old man developed pain and paresthesia on the medial side of the dorsum of his left foot after ankle arthroscopy. An electrodiagnostic study revealed conduction abnormality in the medial branch of superficial peroneal nerve, in which neuroma-in-continuity was subsequently detected by ultrasonography. After neuroma excision and nerve graft, the subject's neuropathic pain was substantially improved.

Ultrasound Visualization of the Superficial Peroneal Nerve in the Mid-calf

THE superficial peroneal nerve (SPN) arises from the common peroneal nerve at the level of the fibular neck and descends in the lateral compartment of the leg. In the distal half of the leg, the SPN is sandwiched between peroneus brevis and the intermuscular septum that separates the anterior and lateral compartments of the leg, and gradually ascends into a superficial location before eventually piercing the crural fascia.1,2 Here the SPN divides into medial and intermediate dorsal cutaneous nerves, which travel subcutaneously to supply the dorsum of the foot.3The SPN is traditionally blocked by “blind” subcutaneous infiltration of local anesthetic across the dorsum of the foot at the intermalleolar line. The SPN may, however, be reliably located and blocked using ultrasound by placing a high-frequency (10–15 MHz) linear-array transducer transversely across the lateral aspect of the leg midway between the fibular head and lateral malleolus. The chief landmark is the fibula, which in cross-section casts an acoustic shadow with a peaked appearance. The “peak” of this shadow points toward the intermuscular septum (IMS) and the SPN. The nerve is visible as a hyper- or hypoechoic structure lying between peroneus brevis (PB) and extensor digitorum longus (EDL) just deep to the crural fascia (dotted arrows, fig. A). The identity of the SPN can be confirmed by tracing it distally toward the ankle, and observing the nerve rise through the crural fascia into a subcutaneous location (fig. B). The nerve may also widen, reflecting its bifurcation into its terminal branches.

Electrophysiological Contribution of Both Sensory Branches of the Superficial Peroneal Nerve in the Diagnosis of Peripheral Neuropathy

ABSTRACT.The aim of this study is to evaluate the simultaneous recording of the medial dorsal cutaneous nerve (MDCN) and the intermediate dorsal cutaneous nerve (IDCN) in the investigation of peripheral neuropathy. We obtained MDCN and IDCN recordings in 35 patients with peripheral neuropathy and in 41 healthy subjects to determine the specificity of the sensory nerve action potential (SNAP) amplitude of each branch separately and of both simultaneously by using the maximal amplitude of either branch. The patients with peripheral neuropathy had low MDCN and IDCN SNAP amplitude in 60% and 14.3% respectively. Though, when recording both MDCN and IDCN simultaneously, the maximum peroneal SNAP amplitude was abnormally low in 68.6%. All the healthy individuals had normal IDCN SNAP amplitude; whereas in 9.7% the MDCN SNAP amplitude was lower than normal. In case of simultaneous recording of both branches the maximum SNAP amplitude was normal in all healthy subjects. Conclusively, the simultaneous amplitude recording of the terminal sensory peroneal branches can better detect abnormal responses in patients with peripheral neuropathy.

Assessment of the Medial Dorsal Cutaneous, Dorsal Sural, and Medial Plantar Nerves in Impaired Glucose Tolerance and Diabetic Patients With Normal Sural and Superficial Peroneal Nerve Responses

OBJECTIVEThis study evaluated the nerve conduction study (NCS) parameters of the most distal sensory nerves of the lower extremities—namely, the medial dorsal cutaneous (MDC), dorsal sural (DS), and medial plantar (MP) nerves—in diabetic (DM) and impaired glucose tolerance (IGT) patients who displayed normal findings on their routine NCSs.RESEARCH DESIGN AND METHODSStandard NCSs were performed on healthy control (HC), DM, and IGT groups (N = 147). The bilateral NCS parameters of the MDC, DS, and MP nerves were investigated. The Toronto Clinical Scoring System (TCSS) was assessed for the DM and IGT groups.RESULTSThe mean TCSS scores of the IGT and DM groups were 2.5 ± 2.3 and 2.8 ± 2.2, respectively. No significant differences between the two groups were observed. After adjustment of age and BMI, the DM group showed significant NCS differences in DS and MDC nerves compared with the HC group (P < 0.05). These differences were also exhibited in the left DS of the IGT group (P = 0.0003). More advanced NCS findings were observed in the DM group. Bilateral abnormal NCS responses in these distal sensory nerves were found in 40 and 16% of DM and IGT patients, respectively.CONCLUSIONSThese results showed that the simultaneous assessment of the most distal sensory nerves allowed the detection of early NCS changes in the IGT and DM groups, even when the routine NCS showed normal findings.

The sentinel vein

Damage to the dorsomedial branch of the medial dorsal cutaneous nerve is not uncommon in surgery of the hallux. The resultant morbidity can be disabling. In the light of the senior author's operative observation of a sentinel vein, we undertook a cadaver study to investigate the anatomical relationships of the dorsomedial branch of the medial dorsal cutaneous nerve. This established that in 14 of 16 cadaver great toes exposed via a modified medial incision, there is an easily identified vein which runs transversely superficial and proximal to the nerve. In a prospective clinical study of 171 operations on the great toe using this approach, we confirmed this anatomical relationship in 142 procedures (83%), with no complaint of numbness or pain in the scar at follow-up. We attribute this to careful identification of the 'sentinel' vein and the subjacent sensory nerve, which had been successfully protected from damage. We recommend this technique when operating on the great toe.

The medial plantar and medial peroneal cutaneous nerve conduction studies for diabetic polyneuropathy

Objective of this study was to determine which nerve conduction is more sensitive electrophysiologically in the diagnosis of polyneuropathy in diabetics by evaluating the sensory conduction in medial plantar nerve and medial peroneal (dorsal) cutaneous nerves. Additionally to investigate the relation between Neuropathy Symptom Score (NSS) and Neuropathy Disability Score (NDS) values used in the diagnosis of these conduction studies. Forty patients with diagnosis diabetic neuropathy were included into this study. In diabetic polyneuropathic patient group, both medial plantar and medial dorsal cutaneous nerve sensory action potential were not bilaterally obtained in 19 patients (47.5%). Sensitivity and specificity of medial dorsal cutaneous nerve and medial plantar nerve sensory conduction abnormalities in diagnosis of diabetic polyneuropathy were higher compared to sural nerve conduction abnormalities. This study showed that both medial plantar and medial dorsal cutaneous nerve conduction study performed bilaterally was a highly sensitive and specific method in diagnosis of diabetic neuropathy.

Variations of the superficial peroneal nerve and its terminal branches in the turkish newborn fetuses

The topography of the superficial peroneal nerve (SPN) and its terminal branches were studied, with the aim of providing further anatomical details for leg and foot in the Turkish newborn fetuses. Limbs from twenty newborn cadavers were dissected. The course of the SPN on the leg and its terminal branches on the foot were investigated. The SPN was lateral (75%), anterior (15%), or branched in both areas (10%) of the cases. The SPN in the dorsum of the feet branched further into medial dorsal cutaneous nerve (MDCn) and intermediate dorsal cutaneous nerve (IDCn). In 82.5% of the cases the MDCn and the IDCn split into three and two branches, respectively. In 10% of the cases, the MDCn gave off three, and the IDCn one terminal branches. In 7.5% of the cases, the MDCn had three while the IDCn had two branches that communicated with the lateral dorsal cutaneous nerve. The course of SPN on the anterolateral surface of the leg and its terminal branches on the dorsal surface of the foot were quite different. This unusual variant location will enable the surgeon to find and preserve the SPN and its terminal branches.

Nerve Conduction Study of the Superficial Peroneal Sensory Distal Branches in Koreans

ObjectiveTo perform nerve conduction studies of the four branches of the superficial peroneal nerves to determine normal values and anatomic variations in Koreans.MethodAntidromic sensory nerve conduction studies of the four distal branches were performed on 70 healthy subjects (100 feet). We applied electrical stimulation at the midpoint of medial and lateral malleoli for the medial dorsal cutaneous nerve (MDCN), and at the lateral 1/4 point between the medial and lateral malleoli for the 2 branches of the intermediate dorsal cutaneous nerve (IDCN).ResultsReference values (mean±SD) of the onset/ peak latency (ms)/ sensory action potential amplitude (µV) for the two branches of the MDCN and for the first branch of the IDCN were 2.2±0.3/2.9±0.3/9.2±3.1, 2.2±0.3/2.8±0.3/9.1±3.0 and 2.3±0.4/2.9±0.3/8.5±2.8, respectively. For the second IDCN branch, the reference values were 2.3±0.4/3.0±0.4/7.1±2.6 but anomalous sural innervation was also found. Three types of IDCN innervations to the fourth interdigital web space were detected. In type I, the fourth interdigital webspace was innervated solely by the IDCN, whereas in type II, it was innervated by both the IDCN and distal sural nerve. In type III, it was solely innervated by the distal sural nerve.ConclusionThe results of this study show the reference values of the distal sensory branches of the superficial peroneal nerve, and provide information on the variant innervations to the fourth interdigital web space.

Paresthesia and hypesthesia in the dorsum of the foot as the presenting complaints of a ganglion cyst of the foot

Although ganglion cysts of the foot represent a substantial amount of lumps in this region, they rarely cause peripheral nerve symptoms. We describe the clinical case of a 43-year-old female with complaints in the previous three months of hypesthesia and paresthesia in the anterior portion of the medial half of the dorsum of her left foot that extended into the first interdigital cleft. She associated the start of her neurological symptoms to the appearance of a lump in the dorsum of the foot. A presumptive diagnosis of compression of the medial branch of the deep fibular nerve and of the medial dorsal cutaneous nerve in the dorsum of the foot by a ganglion cyst was made. Ultrasonography confirmed the cystic nature of the lesion and surgery allowed complete excision of a mass arising from the joint between the medial and intermediate cuneiform bones that was compressing the deep fibular nerve and the medial dorsal cutaneous nerve. Pathological examination confirmed that the lesion was a cystic ganglion. As far as the authors know, the simultaneous compression of the medial branch of the deep fibular nerve and of the medial dorsal cutaneous nerve in the dorsum of the foot by a ganglion cyst has not been described before.

Anatomic variations of superficial peroneal nerve: clinical implications of a cadaver study.

Superficial peroneal nerve and its branches are frequently at risk for iatrogenic damage. Although different studies on anatomical variations of superficial peroneal nerve are available in the medical literature, such reports are rare from India. Hence the present study was undertaken on Indian population. A total of 60 specimens of inferior extremities from 30 properly embalmed and formalin fixed cadavers were dissected and examined for the location and course of the superficial peroneal nerve including number, level, course and distributions of branches. The superficial peroneal nerve in 28.3% specimens was located in the anterior compartment of the leg. In 8.3% specimens the superficial peroneal nerve branched before piercing between the peroneus longus and extensor digitorum longus muscle whereas in 11.7% specimens it branched after piercing the aforementioned muscles and before piercing the deep fascia. In 41 out of 60 specimens the sensory division of superficial peroneal nerve branched into the medial dorsal cutaneous nerve and intermediate dorsal cutaneous nerve distal to its emergence from the deep fascia and proximal to its relation to the extensor retinaculum. In 20 out of 60 specimens the accessory deep peroneal nerve, an additional branch from the sensory division of superficial peroneal nerve, through its course in the anterior compartment of the leg passed deep to the extensor retinaculum and supplied the ankle and the dorsum of foot. Hopefully the present study will help in minimizing iatrogenic damage to the superficial peroneal nerve and its branches while performing arthroscopy, local anesthetic block, surgical approach to the fibula, open reduction and internal fixation of lateral malleolar fractures, application of external fixators, elevation of a fasciocutaneous or fibular flaps for grafting, surgical decompression of neurovascular structures, or miscellaneous surgery on leg, foot and ankle.

The two sensory branches of the superficial peroneal nerve: Electrophysiological differences and correlations with gender, age, height and BMI

To detect amplitude differences between the sensory nerve action potentials (SNAP) obtained by simultaneous recording of the two main branches of the superficial peroneal sensory nerve (SPSN), the medial and intermediate dorsal cutaneous sensory nerves (MDCN, IDCN); to investigate whether these differences, if any, are correlated with gender, age, body mass index (BMI), and height of normal subjects; to discuss their clinical significance. Seventy-six healthy volunteers (36 males) were included (mean age: 36.5 years, range 20-80). Simultaneous MCND and IDCN recordings were performed via surface electrodes placed at precise positions on the intermalleolus line. Stimulation was performed 14 cm proximally on two different sites over the anterolateral aspect of the right leg. Responses were obtained for both nerve branches in all subjects. Median value and lower normal limit for the amplitude of the greater among both MDCN and IDCN responses was 10.95 microV and 4.9 microV, respectively. Statistically significant differences were found between the two branches in median amplitude and frequency of the greater value. These differences were not correlated with gender, age, BMI, or height. We propose simultaneous recording of the two main branches of the superficial peroneal sensory nerve, placing the recording electrodes and stimulation device on precise positions and measuring the amplitude of the best of both responses. This method is an improvement of an already existent one, and may be clinically useful in detecting abnormal responses of the SPSN.

Anatomic basis of sensation restoration of distally based island flap pedicled with nutrient vessels of superficial peroneal nerve

Objective To provide anatomic basis for sensation restoratiou of distally based island flap pedicled with nutrient vessels of superficial peroneal nerve by use of lateral sural cutaneous nerve. Methods The origin, course and distribution rule of lateral part sensory nerve of leg were dissected and observed in 40 antisepticized adult cadaveric limbs. Results ①Lateral sural cutaneous nerve originated from common peroneal nerve 7cm above apex of fibular head, descended short distance along common peroneal nerve, then passed through pepliteal fascia to facies lateralis cruris,along the way it sent out 1-3 terminal branches, which distributed over the skin of Ⅰ , Ⅱ area in the posterior lateral leg. ②Superficial peroneal nerve originated from common peroneal nerve 1.9cm below apex of fibular head, descended forward between peroneus longus and fibula, then descended between peroneus longus and peroneus brevis, and sent out branches to the two muscles. The nerve bole (pure sensory nerve branch) descended straight between peroneus brevis and anterior cmral intermuscular septum, at the juncture between Ⅱ、Ⅲ area in facies lateralis eruris, passed through deep fascia to subcutaneous tissue, then sent out medial dorsal cutaneous nerve of foot and intermediate dorsal cutaneous nerve of foot, which distributed over the skin of dorsum of foot and Ⅲ area in facies lateralis cmris. Conclusion It may be available in sensation restoration of distally based island flap pedicled with nutrient vessels of superficial peroneal nerve through anastomosis of lateral sural cutaneous nerve bole with sensory nervous ramification of recipient site. Key words: Surgical flap; Superficial peroneal nerve; Lateral sural cutaneous nerve; Microsurgery

Distal foot coverage with reverse dorsal pedal neurocutaneous flaps

Various types of neurocutaneous flaps have been used for extremity reconstructions. However, the application of this technique to the dorsum of the foot has not been reported previously. The aim of this article is to evaluate the attempts and clinical results from dorsal pedal neurocutaneous flap procedures. Harvesting of these flaps included the medial, intermediate and lateral dorsal cutaneous nerves, the deep peroneal nerve and the nutrient arteries of these nerves. The vascular anatomy of these flaps was studied before the clinical usage of the procedure. From 2003 to 2008, 30 patients with skin defects and bone exposure of the dorsum of the distal foot were treated with 39 dorsal pedal neurocutaneous flaps in our centre. The flaps in this series ranged from 3.5 to 7.0 cm in width and 4.0 to 10.0 cm in length. Totally, 35 flaps healed uneventfully. One showed partial loss at the distal edge, and three survived entirely following continuous massage. The postoperative contour of the flaps was acceptable. The reverse dorsal pedal neurocutaneous flap has proved effective and convenient for coverage of minor- to medium-sized defects in the distal foot.

Defects of fore foot repaired by reverse medial dorsal neurocutaneous flap of foot in emergency

Objective To investigate the possibility of repairing the defects of fore foot by reverse medial dorsal neurocutaneous flap on foot in emergency.Methods Flap was designed along medial dorsal cutaneous nerve of foot,the axis of the medial branch was the line between lateral part of malleolar middle point and medial part of first metatarsophalangeal joint,and the axis of the lateral branch was the line between middle point of two malleolars and the tip of the great toe webspace,the pedicle located on the distant part of the foot.Based on the size of wound,the flap was cut off from the deep fascia layer,and medial dorsal cutaneous nerve of foot was anastomosed with nerve of digitales plantares proprii.All patients were operated in emergency.Results Eleven patients with defect of fore foot were perfectively recovered and all the wounds healed primarily.The appearances and functions of the foots were satisfactory,with two point sensation of 2-3 cm after 6-11 months postoperatively and without any skin fester.Conclusion Medial dorsal cutaneous nerve of foot has advantages as follows:simply procedures,avoidance of sacrificing major arteries,less harm to donor area,good recovery of sensation.So it is a good method to repair tissue defects of fore foot. Key words: Medial dorsal cutaneous nerve of foot; Surgical flaps; Transplantation; Microsurgery

Anatomy of the superficial peroneal nerve related to the harvesting for nerve graft

The superficial peroneal nerve (SPN) is one of the two main branches of the common peroneal nerve, which become cutaneous nerve on the lateral side of distal leg and dorsum of foot. The use of SPN as nerve graft has been introduced; however, important data regarding the morphometric anatomy of this nerve and its branches, medial and intermediate dorsal cutaneous nerves (MDN and IDN, respectively) to support this application remain incomplete. Eighty-five legs of cadavers were dissected and the branching pattern was classified into Type 1 (penetration of the main trunk of SPN from the deep fascia) or Type 2 (separate penetration of the MDN and IDN). The length of SPN, MDN and IDN from the penetration points until before subsequent branching was measured. In addition, the penetration points were located by referring to the intermalleolar line and the lateral malleolus. Type 1 was found in the majority of specimens independent of gender (71.8%). Asymmetry in the branching pattern was observed in nine cases (20.9%). The average length of the SPN, MDN and IDN without branches was 7.7, 8.1 and 5.5 cm, respectively. The penetration points of the SPN, MDN and IDN were located 5.1, 7.6 and 5.5 cm above the intermalleolar line, respectively. These data are important for using the SPN as a graft.

Anatomical study and primary clinical application of the medial dorsal neurocutaneous flap on foot

目的 为足背内侧皮神经营养血管皮瓣设计提供解剖学依据,并报道其临床应用效果.方法32侧乳胶灌注的成人下肢标本,对足背内侧皮神经及其营养血管进行解剖,观察其起始、直径、走行、分支及分布情况.在此基础上设计足背内侧皮神经营养血管皮瓣应用于临床修复足前端创面3例.结果足背内侧皮神经均续于腓浅神经,行于踝间线时位于中点内侧(0.7±4.3)mm,直径为(2.59±0.54)mm,主干于踝间线远端(3.0±1.5)cm处发出1～3条分支.足背内侧皮神经营养血管平均每侧6.9支,最为恒定的分支穿深筋膜时分别位于踝间线近端(4.1±0.5)cm,直径为(0.81±0.13)mm;第一跖趾关节内侧近端(1.4±0.2)cm,直径(0.48±0.08)mm;第二趾蹼尖近端(1.5±0.3)cm,直径(0.46±0.08)mm.临床应用3例皮瓣均完全成活.结论足背内侧皮神经营养血管皮瓣血供可靠,逆行皮瓣转移是一种理想的修复足前端创面的手术方法。

Branching patterns of the common and superficial fibular nerves in fetus

In this study, we focused on finding out whether branching patterns of the common fibular (CFN) and superficial fibular (SFN) nerves change throughout the early period of life. The popliteal fossa and legs on both sides of 20 fetuses (13 females and 7 males) were dissected. The ages of the fetuses varied between 20 and 36 weeks. The levels where the CFN diverged from the sciatic nerve, the CFN diverged to its terminal branches, and the cutaneous branches of the SFN became superficial and diverged were evaluated, together with the similarity of the patterns of these nerves on both sides. We observed that, comparing with the results of previous studies on adults, both the sciatic and the CFNs in the fetuses were diverging into their terminal branches more distally. Additionally, the SFN appeared to become superficial more proximally in the fetus than in the adult. SFN was piercing the crural fascia before diverging into its terminal branches in 29 legs. Only in 8 of them, it was becoming superficial within the middle one-third of the leg, which was observed more frequently in males (42.9% of 14 legs) than in females (13.3% of 15 legs). But there was no statistically significant gender difference (P = 0.07). The medial dorsal cutaneous (MDCN) and intermediate dorsal cutaneous (IDCN) nerves which were piercing the crural fascia separately were observed in 27.5% of the subjects, all females. In these, MDCN was piercing the fascia superior to the level where the SPN becomes superficial, whereas the IDCN was piercing it to a level lower to this and always in the inferior one-third of the leg. We suggest that the detailed information about the branching patterns of the CPN and SPN in early ages will be beneficial, particularly in tumor and deformity surgery. The reason for different patterns and piercing levels of the nerves may be the effect of the elongating extremity during aging that enforces the fascia and modifies its position with a more stable structure, the nerve.

The Variations of the Sensory Branches of the Superficial Peroneal Nerve Course and its Clinical Importance

Although the sensory branches of the superficial peroneal nerve (SPN) have different anatomical variations that are of clinical importance, little is known about their anatomic courses, branching patterns, or relationships to palpable osseous landmarks.(1,3) A detailed knowledge is necessary for surgical exposures about the foot and ankle, arthroscopic procedures, ankle block anesthesia, and SPN block for leg venography. Thirty lower cadaver limbs were dissected to assess the anatomic properties and the variations of the sensory branches of the SPN. Three distinct branch patterns were determined. In Type 1 (63.3%), the nerve penetrated the crural fascia 80.15 +/- 17.80 mm proximal to the intermalleolar line and then divided into the intermediate dorsal cutaneous nerve (IDCN) and the medial dorsal cutaneous nerve (MDCN) (classic type). In Type 2 (26.7%), the IDCN and MDCN arose independently from the SPN. In Type 3 (10%), the SPN penetrated the crural fascia 101.14 +/- 70.27 mm proximal to the intermalleolar line as a single branch. This single branch had a similar course to the MDCN. Measurements in this study were obtained from palpable bony reference landmarks. Detailed knowledge about the SPN, IDCN, and the MDCN may decrease the damage to these nerves during operative procedures near the foot and ankle.

Navigation for ankle arthroscopy: anatomical study of the anterolateral portal with reference to the superficial peroneal nerve.

We aimed to navigate the surgeon regarding the localization of the main anatomical structures at the anterior part of the ankle joint, in order to find easily the safest anatomical points with reference to the superficial peroneal nerve (SPN), in particular for anterolateral portal placement in ankle arthroscopy. Sixty-three ankles in 36 fresh cadavers were dissected. In all specimens we examined (1) the distance between the SPN bifurcation and the most distal point of the lateral malleolus; and at the level of ankle joint, (2) the number of SPN, (3) the distance between the medial and intermediate dorsal cutaneous nerves, which are branches of the SPN, (4) the localization of the peroneus tertius (PT) tendon in relation to the lateral malleolus, (5) the width of the extensor digitorum longus (EDL) tendon, (6) the relationship of the PT tendon and (7) the relationship of the extensor hallucis longus (EHL) tendon with the SPN. The results were as follows: (1) In 41 ankles with bifurcation (65%) the average distance was 71.8+/-35.3 mm. (2) There were two SPN branches in 39 (62%), three branches in seven (11%) and one branch in 17 (27%) cases. (3) In 39 ankles with two branches of the SPN, the mean distance was 15.2+/-7.1 mm. (4) The lateral border of the PT tendon was positioned a mean distance of 20.8+/-3.3 mm proximal and 25.2+/-5.8 mm medial to the reference points. (5) The mean width was 10.1+/-2.9 mm. (6) In 42 ankles (67%) the distance between the lateral border of the PT tendon and the SPN was a mean of 6.2+/-6.6 mm, median of 3 mm (range 0-22 mm lateral to the tendon). (7) In 56 cases (89%) a branch of the SPN was found a mean of 6.6+/-4 mm and a median of 6 mm lateral to the EHL tendon, and in seven cases (11%) on the tendon. According to our study, in ankle arthroscopy the risk of the SPN injury is maximal in the 0-3 mm lateral to the PT tendon. To avoid injury to the SPN, the safest placement of the anterolateral portal is 4 mm lateral to the PT tendon.