Type and location of flexor hallucis longus musculotendinous junctions and its tendinous interconnections with flexor digitorum longus tendon: Pertinent data for tendon harvesting and transfer

BACKGROUND

Anatomy of flexor hallucis longus (FHL) is essential for the achievement of tendon transfer and several procedures performed in the foot and ankle. The aim of this study was to evaluate the anatomical knowledge of FHL including the type and location of musculotendinous junction (MTJ), tendinous interconnections (TIC) morphology, its location related to Master Knot of Henry (MKH), and the pattern of TIC distribution.

MATERIALS AND METHODS

One hundred and sixty-six legs from 52 embalmed and 31 soft cadavers were assessed. The medial and lateral bellies of FHL (MB and LB) were identified and traced until the end of the most distal muscle fiber to determine the medial and lateral MTJs. MTJ was classified into 4 types based on the existence and length of MB and LB: Type 1, long LB and shorter MB; Type 2, equal length of both bellies; Type 3, only LB and no MB; Type 4, long MB and shorter LB. Low lying muscle belly was defined as muscle extending beyond the zero point (the point of intersection between distal osseous part of tibia and FHL tendon). The distance between MTJ and zero point was measured. TIC was classified into seven types based on the direction and number of slip: Type I, one slip from FHL to FDL; Type II, crossed connection: Type III, one slip from FDL to FHL; Type IV, no connection; Type V, two slip from FHL to FDL; Type VI, two slip from FHL to FDL and one slip from FDL to FHL; Type VII, two slips from FDL to FHL and one slip from FHL to FDL. The distance between the TIC and MKH was measured. TIC distribution was defined into four types based on slip distribution to lesser toes: type a, distributed to second toe; type b, distributed to second and third toes; type c, distributed to second to fourth toes, and type d, distributed to second to fifth toes.

RESULTS

Type 1 and type 3 of MTJ morphology were found in 87.3% and 12.7%, respectively. Low lying LB was detected in 66.13% of cases with a mean distance of 13.10±4.51 mm. All MBs ended proximal to the zero point with a mean distance of -21.99±13.21 mm. Three types of TIC (I, II, V) were identified. The highest frequency was type I (82.93%). In addition, a new type of TIC was depicted in 8.53% of cases. Part of the FHL tendon in this type fused with FDL tendon and the rest extended directly to the first toe. TIC could be located either proximal, distal or at the MKH. The highest prevalence was distal to MKH in 51.67% of cases with a mean distance of 11.23+5.13 mm and 8.73+4.2 mm in low lying and non-low-lying groups, respectively. Four types of slip distribution to lesser toes were defined, mostly in type b. No statistically significant differences were detected among all parameters including genders, sides, and groups.

CONCLUSIONS

Knowledge of this investigation might enhance the clinical efficacy of tendon harvesting and transfer in foot and ankle surgery.

Evaluation of the greater occipital nerve location regarding its relation to intermastoid and external occipital protuberance to mastoid process lines

BACKGROUND

Localisation of the greater occipital nerve (GON) is essential for the achievement of several procedures performed in the occipital region especially the treatment of occipital neuralgia. This study proposed to investigate the location of GON subcutaneous (Sc) and semispinalis capitis (SSC) piercing points related to the intermastoid and external occipital protuberance (EOP) to mastoid process (MP) lines.

MATERIALS AND METHODS

The Sc piercing point, relation to SSC and obliquus capitis inferior (OCI) muscles of 100 GONs from 50 cadaveric heads (23 males, 27 females) were dissected. Distances from EOP to MP (EM line) on both sides and between MPs (MM line) were measured. Perpendicular lines from Sc and SSC piercing points to EM and MM lines were created and measured. Distances from EOP to the perpendicular lines of SSC piercing point and from MP to the perpendicular lines of Sc piercing point were measured and calculated into percentage of EM and MM length, respectively.

RESULTS

Three types of Sc piercing points (I, II and III) were obtained. The percentage of GON piercing trapezius muscle (TP) (type I), aponeurosis of TP (type II) and aponeurosis between TP and sternocleidomastoid muscle (SCM) (type III) were 2, 67 and 31, respectively. In addition, 95% of GON pierced SSC, 2% pierced its tendinous band and 3% travelled between its medial fibres and the nuchal ligament. 94% of the GON turned around the lower edge of the OCI, while 6% pierced the lower edge of this muscle. Sc piercing point was always located above the MM line, but it could be above, below or on the EM line. In contrast, all of the SSC piercing points were located below the EM line except in one specimen, but it could be above, below or on the MM line. Therefore, the MM and EM lines were used as reference lines for locating the Sc and SSC piercing points, respectively. The mean EM line length was 81.26 ± 5.26 mm with statistically significant differences between genders and sides in female. The mean MM line length was 121.77 ± 8.54 mm with a statistically significant difference between genders. Sc piercing point could be located at 44% of MM line length from ipsilateral MP with a mean vertical distance of 18 mm. No statistically significant difference was found between genders and sides in these parameters, but a statistically significant difference was found in the percentage of MB to MM line between type III and type I (p = 0.02). SSC piercing point of all types could be located at the point of 25% of EM line length from EOP with a vertical distance of 18 mm below EM line. No statistically significant difference was found between genders, sides and types of both piercing points.

CONCLUSIONS

MM and EM lines are potential reference lines for locating the Sc and SSC piercing points of GON, respectively.

Surface localisation of master knot of Henry, in situ and ex vivo length of flexor hallucis longus tendon: pertinent data for tendon harvesting and transfer

BACKGROUND

Length of flexor hallucis longus (FHL), localisation of master knot of Henry (MKH) and relationship between MKH and neurovascular bundle are essential for the achievement of FHL tendon transfer. The purpose of this study is to define the localisation of MKH in reference to bony landmarks of the foot, its relationship to plantar neurovascular bundle and to investigate in situ and ex vivo length of FHL tendon in single incision, double incision and minimally invasive techniques.

MATERIALS AND METHODS

Foot length was examined in 62 feet of 31 soft cadavers (9 males, 22 females). Various parameters including the relationship between MKH and neurovascular bundle, the distances from MKH to medial malleolus (MM), navicular tuberosity (NT) and the first interphalangeal joint of great toe (IP) were measured. Surface localisation of MKH in relation to a line joining the medial end of plantar flexion crease at the base of great toes (MC) to NT (MC-NT line) was determined. Lengths of FHL tendon graft from three surgical techniques were examined. In situ length was measured in the plantar surface of foot and ex vivo length was measured after tendon was cut from its insertion.

RESULTS

The mean length of foot was 230.98 ± 15.35 mm with a statistically significant difference between genders in both sides (p < 0.05). No distance was found between medial plantar neurovascular bundle (MPNVB) and MKH. Mean distance of 17.13 ± 3.55 mm was found between lateral plantar neurovascular bundle (LPNVB) and MKH. MKH was located at a mean distance of 117.11 ± 1.00 mm proximal to IP, 26.28 ± 4.75 mm under NT and 59.58 ± 7.51 mm distal to MM with a statistically significant difference of MKH-IP distance between genders in both sides and MKH-NT in right side. MKH was located anterior to NT (66.1%), at NT (27.4%) and posterior to NT (6.5%) on the MC-NT line. Surface localisation of MKH was 94.75 ± 8.43% of MC-NT line from MC with a perpendicular distance of 25.11 ± 5.37 mm below MC-NT line. The in situ and ex vivo tendon lengths from MTJ to ST, to MKH and to IP were 39.05 ± 10.88 mm and 34.43 ± 10.23 mm, 73.45 ± 9.91 mm and 68.63 ± 9.43 mm, 197.98 ± 13.89 and 191.79 ± 14.00 mm, respectively. A statistically significant difference between genders was found in MTJ-IP of in situ and ex vivo length of both sides (p < 0.05). The mean length of tendon between in situ and ex vivo was significantly different in all techniques (p < 0.05). A moderate positive correlation between foot length and tendon length was found in MTJ-IP of both in situ and ex vivo tendon length.

CONCLUSIONS

A statistically significant difference between in situ and ex vivo tendon length was shown in all harvesting techniques. Surface location of MKH was approximately at 95% of MC-NT line from MC with a perpendicular distance of 25 mm from MC-NT line.

Evaluation of the sciatic nerve location regarding its relationship to the piriformis muscle

BACKGROUND

The localisation of sciatic nerve (SN) is essential for the achievement of several procedures performed in the gluteal region. This study proposed to investigate the location of SN regarding its relationship to the piriformis (PM) by the line joining the posterior superior iliac spine (PSIS), ischial tuberosity (IT) and greater trochanter (GT).

MATERIALS AND METHODS

SN-PM relationship was examined in 204 specimens from 102 embalmed cadavers (55 males, 47 females). Distances between PSIS, IT and GT were measured. Midpoints of SN at the lower edge of PM (S1) and IT-GT line (S2) were marked. Perpendicular line from S1 to PSIS-GT (S1-R) and to PSIS-IT (S1-Q), were created and measured. Distances of PSIS-R, PSIS-Q (S1) and IT-S2 were measured and calculated into percentage of PSIS-GT, PSIS-IT and IT-GT lengths, respectively.

RESULTS

Regarding the classification of Beaton and Anson, three types of SN-PM relationship (a, b and c) were obtained. The percentage of type a, b and c was 74.02, 22.55 and 3.43, respectively. Symmetrical SN-PM relationship was found in 75.49%. The mean length of PSIS-IT, PSIS-GT and IT-GT in all types was 129.63 ± 11.89 mm, 151.34 ± 14.78 mm and 73.02 ± 10.20 mm, respectively. A statistically significant difference was found between types a and b (p = 0.013) in PSIS-IT length, whereas mean length of IT-GT and PSIS-GT showed no statistically significant difference between SN-PM types. PSIS-IT line passed SN at the lower edge of PM (S1) in 112 specimens (54.90%). In these cases, S1 and Q were the same point. A statistically significant difference was also found between types a and b (p = 0.023) in PSIS-Q (S1) length. The mean lengths of PSIS-Q (S1), PSIS-R and IT-S2 in term of percentage of PSIS-IT, PSIS-GT and IT-GT line in all types were 60.06 ± 5.90%, 54.19 ± 6.10%, and 37.87 ± 8.27%, respectively. The mean lengths of S1-R and S1-Q were 30.07 ± 8.30 mm and 6.54 ± 7.99 mm. Therefore, SN at S1 could be located at the point of 54.19 ± 6.10% of PSIS-GT length (R) with a distance of 30.07 ± 8.30 mm perpendicular to PSIS-GT line (S1-R). Since the PSIS-IT line did not pass SN at S1 in every case, it might not be suitable for localizing SN at S1. SN at S2 could be located at the point of 37.87 ± 8.27% of IT-GT line. No significant difference was found between types.

CONCLUSIONS

Sciatic nerve can be localised by PSIS-GT and IT-GT lines without statistically significant difference between types (a, b, and c) of SN-PM relationship.

Morphometric study of inferior peroneal retinaculum and contents of inferior peroneal tunnel

BACKGROUND

The aims of this study are to investigate the inferior peroneal retinaculum (IPR) regarding morphometric parameters, and contents in the inferior peroneal tunnel (IPT).

MATERIALS AND METHODS

One hundred and nine embalmed cadaveric legs were dissected in prone position.

RESULTS

The extension band of the IPR was found in 31.19% of cases. The mean of length, width at the origin, width at the middle part, width at the insertion, and thickness of the IPR [mm] were 23.42 ± 3.54 (17.05-33.68), 13.29 ± 2.56 (5.83-20.92), 14.50 ± 2.37 (6.68-21.34), 10.10 ± 2.63 (4.59-19.17) and 0.48 ± 0.16 (0.20-0.87), respectively. The angle of the IPR to the horizontal axis was 38.51 ± 7.07 (11.67-54.00) degrees. The IPT was divided into the upper and lower tunnels. The normal contents were the tendons of peroneus brevis and peroneus longus in the upper and lower tunnels, respectively. However, additional contents were found in the upper tunnel in 2 cases. One was the tendon of peroneus digiti quinti, and peroneus quartus in the other one. Moreover, an unusual accessory peroneal muscle coursed into the lower tunnel and inserted on the peroneal tubercle. Tears of the peroneus brevis tendon were observed in 2 cases.

CONCLUSIONS

These morphometric data might be beneficial in surgical repair for IPR injury.

Co-existence of the double inferior vena cava with complex interiliac venous communication and aberrant common hepatic artery arising from superior mesenteric artery: a case report

Variations of the arterial and venous system of the abdomen and pelvis have important clinical significance in hepatobiliary surgery, abdominal laparoscopy, and radiological intervention. A case of double inferior vena cava (IVC) with complex interiliac communication and variation of the common hepatic artery (CHA) arising from superior mesenteric artery (SMA) in a 79-year-old male cadaver is presented. Both IVCs ascended on either side of the abdominal aorta. The left-sided IVC crossed anterior to the aorta at the level of the left renal vein. The union of both IVCs was at the level just above the right renal vein. The diameter of right-sided IVC, left-sided IVC and the common IVC were 16.73 mm, 21.57 mm and 28.75 mm, respectively. In the pelvic cavity, the right common iliac vein was formed by a union of right external and internal iliac veins while the formation of left common iliac vein was from the external iliac vein and two internal iliac veins. An interiliac vein ran from right internal iliac vein to left common iliac vein with an additional communicating vein running from the middle of this interiliac vein to the right common iliac vein. Another co-existence variation in this case was the origin of the CHA arising from the SMA with a suprapancreatic retroportal course. Clinical importance of double IVC are observed in retroperitoneal surgery, whole organ transplantation or radical nephrectomy, surgical ligation of the IVC or the placement of an IVC filter for thromboembolic disease. The variation of CHA has an important clinical significance in liver transplantation, abdominal laparoscopy and radiological abdominal intervention. (Folia Morphol 2018; 77, 1: 151-155).

Multiple variations in the course and motor branching pattern of the musculocutaneous nerve with unusual communication with the median nerve

Anatomic variations in course and motor branching pattern of the musculocutaneous nerve (MCN) with unusual communication with the median nerve were determined on the left arm of a 62-year-old formalin fixed male cadaver. The MCN did not pierce the coracobrachialis muscle. It provided 4 primary motor branches. The first branch emerged 1.5 cm inferior to the coracoid process to innervate the coracobrachialis muscle. The second branch emerged 8 cm inferior to the coracoid process to innervate the biceps brachii muscle. The third branch to brachialis muscle emerged 13.9 cm inferior to the coracoid process. The last branch to the common belly of biceps brachii muscle emerged 19.6 cm inferior to the coracoid process. Two communications with the median nerve were observed. The proximal thick communicating branch had the direction from the MCN to the median nerve while the distal one was a small nerve bundle with a direction from the median nerve to the MCN. The present report provided evidence of multiple variations in one MCN which had not been reported previously. Anatomic variation in this case has clinical implications, considering that injury of the MCN in the upper part of arm would cause unexpected paralysis of flexor muscles of forearm and thenar muscle due to communications between this and median nerve.

Morphometric data of normal sural nerve in Thai adults

Morphometry has an important role in the interpretation of sural nerve biopsies. It is used for early detection of structural abnormalities in peripheral neuropathies. This application requires a comparison with data of normal population. However, most data in the literature were of Western subjects with a small number of samples. In this study the authors reported the morphometric data of sural nerve harvested within 24 hours after death from 78 Thai subjects without known causes of neuropathy. The samples were transversely sectioned and analyzed for the number and area of fascicles, the total number of myelinated axons, myelinated fiber diameter; myelinated axon diameter, myelin sheath thickness, g ratio and myelinated axon density. Results were discordant in some measurement parameters compared to previous reports. These data are valuable for the early recognition of peripheral nerve diseases from biopsied sural nerve of Thai subjects.