Superficial Tendon Research Articles

Insertional achilles tendinopathy associated with altered transverse compressive and axial tensile strain during ankle dorsiflexion.

The purposes of this case-control study (N = 20) were to examine the effects of insertional Achilles tendinopathy (IAT) and tendon region on tendon strain in patients with IAT compared to a control group without tendinopathy. An ultrasound transducer was positioned over the Achilles tendon insertion during dorsiflexion tasks, which included standing and partial squat. A non-rigid image registration-based algorithm was used to estimate transverse compressive and axial tensile strains of the tendon from radiofrequency ultrasound images, which was segmented into two regions (superficial tendon and deep). For transverse compressive strain, two-way mixed effects ANOVAs demonstrated that there were interaction effects between group and tendon region for both dorsiflexion tasks (Heel lowering, p = 0.004; Partial squat, p = 0.008). For axial tensile strain, the IAT group demonstrated a main effect of lower tensile strain than the control group (Standing, p = 0.001; Partial squat, p = 0.033). There was also a main effect of greater tensile strain in the superficial region of the tendon compared to the deep during standing (p = 0.002), but not during partial squat (p = 0.603). Reduced transverse compressive and axial tensile strains in the IAT group indicate altered mechanical properties specific to the region of IAT pathology. Additionally, patterns of compressive strain are consistent with the theory of calcaneal impingement contributing to IAT pathology. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:910-915, 2017.

The angular course of the median nerve in the distal forearm and its anatomical importance in preventing nerve injury in a modern era of carpal tunnel release.

OBJECTIVE A thorough understanding of anatomy is critical for successful carpal tunnel release. Several texts depict the median nerve (MN) as taking a course parallel to the long axis of the forearm (LAF). The authors report on their attempt to formally assess the course of the MN as it travels to the carpal tunnel in the distal wrist and discuss its potential clinical significance. METHODS The width of the wrist, the distance from the radial wrist to the MN, and the distance from the distal volar wrist crease to the point where the MN emerges between the flexor carpi radialis (FCR) tendon and the flexor digitorum superficialis (FDS) tendons were recorded during cadaveric dissection of 76 wrist specimens. The presence or absence of palmaris longus was documented. Finally, the angles between the MN and FCR tendon and between the MN and the LAF were measured using ImageJ. RESULTS The relative position of the MN at the distal wrist crease, as determined by the ratio of the distance from the MN to the radial wrist divided by wrist width, revealed a mean value of 0.48, indicating that the nerve was usually located just radial to midline. The mean distance between the distal wrist crease and the MN's emergence was 34.6 mm. The mean angle between the MN and the FCR tendon was 14.1°. The angle between the MN and the LAF had a mean value of 8.8° (range 0.0°-32.2°). The nerve was parallel to the LAF in only 10.7% of the studied wrists. Palmaris longus was absent in 14 (18.4%) of the 76 wrists. CONCLUSIONS The MN takes an angular approach to the carpal tunnel in the distal wrist in the vast majority of cases. This newly described finding will be useful to both clinicians and anatomists.

Comparison of the Thickness of Pulley and Flexor Tendon Between in Neutral and in Flexed Positions of Trigger Finger.

Objective:This study aims to compare the morphology of the A1 pulley and flexor tendons in idiopathic trigger finger of digits other than the thumb between in neutral position and in the position with the interphalangeal joints full flexed and with the metacarpophalangeal (MP) joint 0° extended (hook grip position).Method:A total of 48 affected digits and 48 contralateral normal digits from 48 patients who initially diagnosed with idiopathic trigger finger were studied sonographically. Sonographic analysis was focused on the A1 pulley and flexor tendons at the level of the MP joint in the transverse plane. We measured the anterior-posterior thickness of A1 pulley and the sum of the flexor digitorum superficialis and profundus tendons, and also measured the maximum radialulnar width of the flexor tendon in neutral and hook grip positions, respectively. Each measurement was compared between in neutral and in hook grip positions, and also between the affected and contralateral normal digits in each position.Results:In all the digits, the anterior-posterior thickness of flexor tendons significantly increased in hook grip position as compared with in neutral position, whereas radial-ulnar width significantly decreased. Both the A1 pulley and flexor tendons were thicker in the affected digits as compared with contralateral normal digits.Conclusion:The thickness of flexor tendons was significantly increased anteroposteriorly in hook grip position as compared with in neutral position. In trigger finger, A1 pulley and flexor tendon were thickened, and mismatch between the volume of the flexor tendon sheath and the tendons, especially in anterior-posterior direction, might be a cause of repetitive triggering.

Biomechanical investigation of 'figure of 8' flexor tendon repair techniques.

This biomechanical study compared the original Al-Qattan repair with other modifications postulated to reduce bulk and friction, thereby potentially improving outcome. A total of 32 cadaveric digits with intact flexor apparatus were used. In each digit, the flexor digitorum profundus and flexor digitorum superficialis tendons were cut cleanly in Zone 2. We tested Al-Qattan's technique along with three modifications using stronger suture material and varying the number of strands across the repair site. Of the four repair techniques, the modified Al-Qattan's technique using two 'figure of 8' 4-0 Fiberwire core sutures (Group 4) had the best balance of ultimate tensile strength (50.9 N), 2 mm gapping force (38 N) and friction. The modified technique provided a stronger repair for early active mobilization and has less friction than the originally described repair.

Volar Central Portal in Wrist Arthroscopy.

Background Nowadays, the wrist is not limited to a dorsal visualization; the joint can be thought of as a "box," which can be visualized from almost every perspective. The purpose of this study was to describe a new volar central portal for the wrist, following three principles: a single incision that allows access to both the radiocarpal and midcarpal joints, centered on the lunate, with the volar structures at risk protected not only by retractors, but also by tendons. Description of Technique The incision begins in the distal wrist crease and extended 1.5 cm proximally up to the proximal wrist crease, following the axis of the third intermetacarpal space. The flexor superficialis tendons are identified and retracted toward the radial side. Next, the fourth and fifth flexor digitorum profundus tendons are retracted toward the ulnar side, while the third and second tendons are retracted toward the radial side. The volar central midcarpal portal is performed under direct vision just over the anterior horn of the lunate through the Poirier space. The volar central radiocarpal portal is created under the lunate through the interval between the ulnocarpal ligaments and the short radioulnar ligament. Methods An anatomical study was performed on 14 cadaver specimens. Two data were recorded: iatrogenic injuries of the structures at risk and the distances to the structures at risk. Results The median (interquartile range [IQR]) distances from the volar central radiocarpal portal to the median nerve, palmar cutaneous branch of the median nerve, and ulnar neurovascular bundle were 10.5 (7.8-15.0), 18.5 (15.8-20.3), and 7.0 (5.0-10.5) mm, respectively. The median (IQR) distances from the volar central midcarpal portal to the median nerve, palmar cutaneous branch of the median nerve, and ulnar neurovascular bundle were 7.0 (4.8-10.3), 16.0 (14.8-19.0), and 4.5 (3.8-9.0) mm, respectively. No iatrogenic injuries were observed. Conclusion The volar central portal is reproducible and safe. The risk of iatrogenic injury is low. The capsule is pierced through one of its thinner portions, and both the radiocarpal and midcarpal joints can be inspected through one single incision.

Bifid Median Nerve Complete Transection at the Wrist.

A 17-yr-old male patient was admitted with a transverse sharp transection caused by broken glass at the volar aspect of his left wrist. Clinical examination showed loss of sensation at the distribution of the median nerve to the thumb, index, and middle finger and an inability to flex the middle finger. Under regional anesthesia and a high humerus tourniquet, surgical exploration of the wound with binocular loupe magnification showed a bifid median nerve with a persistent thin median artery running between the two nerve trunks. The bifid median nerve was sharply and transversely transected, slightly proximal to the transverse carpal ligament. The palmaris longus tendon and the flexor digitorum superficialis tendon of the middle finger were also cut. The flexor digitorum tendon was sutured with a two-strand technique augmented with a running epitendinous suture. The two trunks of the bifid median nerve were repaired separately using microsurgical technique and 8-0 nylon epineural sutures. Postoperatively, the hand was immobilized in a palmar short-arm splint that was removed at 40 d. A progressive Tinel sign was evident 30 d postoperatively. At 3 mo, the patient experienced light touch sensation at the tip of the index and middle fingers. At the last follow-up, 2.5 yr after his injury, the patient has complete nerve functional recovery without atrophy of the thenar muscles and with strong thumb opposition.

Résultats et complications des transferts fléchisseurs superficiels–fléchisseurs profonds chez le patient cérébrolésé – une série de 26 patients

Introduction The hand of the spastic patient combines motor deficit, abnormal muscle tone causing spasticity, and sensory defect. The purpose of the surgical program could be functional by restoring grasp or nonfunctional by resolving hygienic problems and improving cosmetic appearance due to the clenched fist deformity. The superficialis-to-profundus tendon transfer, first described by Braun et al., allows the opening of nonfunctional hands. The aim of our study was to confirm the efficacy of this technique to correct vicious attitudes, to highlight a possible functional gain and finally to identify any complications. Materials and methods Patients (9 women and 17 men, aged 36–79 years) were evaluated by a team of rehabilitation physicians and orthopedic surgeons. Palliative transfer of the flexor digitorum superficialis tendons to the flexor digitorum profundus tendons has been achieved. Pictures were taken both preoperatively and during follow-up consultations. The hands were classified according to their appearance- the position of the wrist and fingers (Keenan et al.). Surgery complications were sought. Results Mean follow-up was 47 months. Preoperatively, all hands were classified type 5 (closed hand no distance between palm and pulp). Postoperatively, 38% of patients have type 1 hand (wrist in neutral position, metacarpophalangeal joints (MCP) and proximal interphalangeal (PIP) at 20° of flexion) and 46% type 2 hand (fingers are more flexed [MCP and PIP at 40° of flexion]), with good cosmetic appearance. None of them have hygienic problems. Mean House score increased from 0 to 0.9, with 7 patients improved. Four patients had an attitude of supination of the forearm, 10 had an intrinsic-plus deformity and 6 had swan neck deformity of the finger. Secondary procedures had to be made. Conclusion This transfer gives satisfactory results on the opening of the hand but with significant complications. Intrinsic spasticity may be unmasked. Accessories pronator muscles release, while the biceps is spastic, can lead to an attitude of supination of the forearm, which causes functional and esthetic problems.

Results and complications of transfer of the flexor digitorum superficialis tendons to the flexor digitorum profundus tendons in the spastic patient: A series of 26 patients

The hand of the brain damaged patient combines motor deficit, abnormal muscle tone causing spasticity, and sensory defect. The purpose of surgical program could be functional by restoring grasp or non-functional by resolving hygienic problems, and improving cosmetic appearance due to the clenched fist deformity. The superficialis-to-profundus tendon transfer, first described by Braun and al., allows the opening of non-functional hands. The aim of our study was to confirm the efficacy of this technique to correct vicious attitudes, to highlight a possible functional gain and finally to identify any complications. Patients (9 women and 17 men, aged 36–79 years) were evaluated by a team of rehabilitation physicians and orthopeadic surgeons. Palliative transfer of the flexor digitorum superficialis tendons to the flexor digitorum profundus tendons has been achieved. Pictures were taken both preoperatively and during follow-up consultations. The hands were classified according to their appearance: the position of the wrist and fingers (Keenan and al.). Surgery complications were sought. Mean follow-up was 47 months. Preoperatively all hands were classified type 5 (closed hand: no distance between palm and pulp). Postoperatively 38% of patients have type 1 hand (wrist in neutral position, metacarpophalangeal joints [MCP] and proximal interphalangeal [PIP] at 20° of flexion) and 46% type 2 hand (fingers are more flexed [MCP and PIP at 40° of flexion]), with good cosmetic appearance. None of them have hygienic problems. Mean House score increased from 0 to 0.9, with 7 patients improved. Four patients had an attitude of supination of the forearm, 10 had an intrinsic-plus deformity and 6 had swan neck deformity of the finger. Secondary procedures had to be made. This transfer gives satisfactory results on the opening of the hand but with significant complications. Intrinsic spasticity may be unmasked. Accessories pronator muscles release, while the biceps is spastic, can lead to an attitude of supination of the forearm, which causes functional and esthetic problems.

Outcome of flexor digitorum superficialis opponensplasty for Type II and IIIA thumb hypoplasia.

This study reports on outcomes of the flexor digitorum superficialis tendon transfer from the ring finger in Type II and IIIA hypoplastic thumbs. We included 22 patients with 27 involved hands: 16 Type II thumbs and five Type IIIA treated by transfer and six non-operated Type II thumbs. The outcomes were assessed by range of motion, strength, sensibility, joint stability and patient/parent satisfaction. Compared with normative data, the range of motion was diminished in all patient groups. Opposition strength in operated Type II thumbs was significantly better than in non-operated thumbs. Grip strength, pinch strength, tripod strength and key pinch strength were approximately 50% of normal in Type II thumbs and 35% in Type IIIA thumbs. Metacarpophalangeal joint stability was restored in all operated Type II thumbs and in 40% of Type IIIA thumbs. We conclude that the flexor digitorum superficialis tendon transfer of the ring finger is a good functioning opponensplasty in both Type II and IIIA thumbs. The transfer provides excellent stability of the metacarpophalangeal joint in Type II thumbs. Level IV.

Biomechanical Study of the Digital Flexor Tendon Sliding Lengthening Technique

To compare the mechanical properties of sliding lengthening (SL) and Z-lengthening (ZL) for flexor tendon elongation used for conditions such as Volkmann contracture, cerebral palsy, and poststroke spasticity. We harvested 56 flexor tendons, including flexor pollicis longus tendons, flexor digitorum superficialis tendons (zones II to IV), and flexor digitorum profundus tendons (zones II to V) from 24 upper limbs of 12 fresh cadavers. Each tendon was harvested together with its homonymous tendon from the opposite side of the cadaver and paired. We used 28 pairs of tendons and divided them randomly into 4 groups depending on the lengthening distance (20 or 30 mm) and type of stitching (single or double mattress sutures). Then we divided each pair into either the SL or ZL group. Each group was composed of 7 specimens. The same surgeon lengthened all tendons and stitched them with 2-0 polyester sutures. We tested biomechanical tensile strength immediately after completing lengthening and suturing in each group. Ultimate tensile strengths were: 23 N for the SL 20-mm lengthening and single mattress suture and 7 N for the ZL; 25 N for the SL 20-mm lengthening and double mattress suture and 10 N for the ZL; 15 N for the SL 30-mm lengthening and single mattress suture and 8 N for the ZL; and 18 N for the SL 30-mm lengthening and double mattress suture and 10 N for the ZL. The SL technique may be a good alternative to the ZL technique because it provides higher ultimate tensile strength. Because of its higher ultimate tensile strength, the SL technique may allow for earlier rehabilitation and reduced risk of postoperative complications.

Connective tissue adaptations in the fingers of performance sport climbers

This study investigates the changes of the connective tissue in the fingers of performance sport climbers resulting after a minimum of 15 years of climbing. Evaluation was performed by ultrasonography on the palmar side of the fingers (Dig) II–V to measure the thickness of the A2 and A4 annular pulleys, the flexor digitorum superficialis (FDS) and profundus (FDP) tendons and the palmar plates (PP's) of the proximal interphalangeal (PIP) as well as distal interphalangeal (DIP) joint in sagittal and axial direction. Totally, 31 experienced male sport climbers (mean age 37y, 30–48y grade French scale median 8b, range 7b+ to 9a+) participated in the study. The control-group consisted of 20 male non-climbers (age 37y, 30–51y). The A2 and A4 pulleys in climbers were all significantly thicker (A2 Dig III 62%, Dig IV 69%; A4 Dig III 69%, Dig IV 76%) as compared to non-climbers pulleys. All PP's of the DIP joints were also significantly thicker, particularly at Dig III and IV (76 and 67%), whereas the PP's at PIP joints were only scarce significant for three joints. Differences of the diameter of the flexor tendons were less distinct (1–21%) being significant only over the middle phalanx. High load to the fingers of rock climbers after a minimum of 15 years of climbing years induced considerable connective tissue adaptions in the fingers, most distinct at the flexor tendon pulleys and joint capsule (PP) of the DIP joints and well detectable by ultrasound.

Rice Body Tenosynovitis without Tuberculosis Infection after Multiple Acupuncture Procedures in a Hand.

Rice Body Tenosynovitis without Tuberculosis Infection after Multiple Acupuncture Procedures in a Hand.

In vivo flexor tendon forces generated during different rehabilitation exercises.

We measured in vivo forces in the flexor digitorum profundus and the flexor digitorum superficialis tendons during commonly used rehabilitation manoeuvres after flexor tendon repair by placing a buckle force transducer on the tendons of the index finger in the carpal canal during open carpal tunnel release of 12 patients. We compared peak forces for each manoeuvre with the reported strength of a flexor tendon repair. Median flexor digitorum profundus force (24 N) during isolated flexor digitorum profundus flexion and median flexor digitorum superficialis force (13 N) during isolated flexor digitorum superficialis flexion were significantly higher than during the other manoeuvres. Significantly higher median forces were observed in the flexor digitorum superficialis with the wrist at 30° flexion (6 N) compared with the neutral wrist position (5 N). Median flexor digitorum profundus forces were significantly higher during active finger flexion (6 N) compared with place and hold (3 N). Place and hold and active finger flexion with the wrist in the neutral position or tenodesis generated the lowest forces; isolated flexion of these tendons generated higher forces along the flexor tendons. III (controlled trial without randomization).

Zancolli lasso procedure for correction of paralytic claw hands.

To evaluate the outcome of 20 claw hands corrected with the Zancolli lasso procedure. 20 patients aged 7 to 48 (mean, 28) years with claw hand deformity for a mean of 33.3 months secondary to leprosy (n=17), traumatic ulnar nerve injury (n=2), or tardy ulnar nerve palsy (n=1) underwent the Zancolli lasso procedure, in which the flexor digitorum superficialis (FDS) of the middle finger was divided in to 4 slips (one for each finger) and reattached to itself after passing through the proximal pulley. Deformity, power, movement, and function of the hands were evaluated before and after surgery. The mean duration of surgery was 58.4 (range, 50-107) minutes. The mean duration of follow-up was 18 (range, 12-24) months. Deformity correction was good in 15 patients, fair in 3, and poor in 2. The mean angle improvement was maximum in the little finger, followed by the ring, index, and middle fingers. The transverse metacarpal arch (compared with the normal hand) was increased/reversed in 7 patients and decreased in 13 patients. The grip and pinch strength increased in 13 patients, remained unchanged in 6, and decreased in one. Motion and function of the hand was good in 12 patients, fair in 6, and poor in 2. One patient developed swan neck deformity in the little finger owing to suture tension of the transferred slip, and another had paraesthesia over the index finger. They underwent reoperation using the FDS of the ring finger; no sensory or motor recovery was achieved. The Zancolli lasso procedure is easy to perform and does not require extensive postoperative training. It restores synchronous finger flexion and spares other superficialis tendons, thus avoiding swan neck deformity of the fingers.

Validation of color Doppler sonography for evaluating relative displacement between the flexor tendon and subsynovial connective tissue.

A common pathologic finding in carpal tunnel syndrome is fibrosis and thickening of the subsynovial connective tissue. This finding suggests an etiology of excessive shear forces, with relative longitudinal displacement between the flexor tendon and adjacent subsynovial connective tissue. The purpose of this study was to validate color Doppler sonography for measurement of tendon displacement over time. Eight unmatched fresh frozen cadaver arms were used to evaluate color Doppler sonography for measurement of tendon displacement. The middle flexor digitorum superficialis tendon was moved through a physiologic excursion of 20 mm at 3 different tendon velocities (50, 100, and 150 mm/s). We found that color Doppler sonography provided accurate measurement of tendon displacement, with absolute errors of -0.05 mm (50 mm/s), -1.24 mm (100 mm/s), and -2.36 mm (150 mm/s) on average throughout the tendon excursion range. Evaluating relative displacement between the tendon and subsynovial connective tissue during finger flexion-extension movements also offered insight into the gliding mechanism of the subsynovial connective tissue. During flexion, we observed a curvilinear increase in relative displacement, with greater differential motion at the end range of displacement, likely due to the sequential stretch of the fibrils between successive layers of the subsynovial connective tissue. In extension, there was a linear return in relative displacement, suggesting a different unloading mechanism characterized by uniform relaxation of fibrils. We demonstrated the validity of color Doppler displacement for use in the evaluation of relative motion. Color Doppler sonography is useful in our understanding of the behavior of the subsynovial connective tissue during tendon excursion, which may elucidate the role of finger motion in the etiology of shear injury.

Development of a kinematic model to predict finger flexor tendon and subsynovial connective tissue displacement in the carpal tunnel

Finger flexor tendinopathies and carpal tunnel syndrome are histologically characterised by non-inflammatory fibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel, which is indicative of excessive and repetitive shear forces between the finger flexor tendons and SSCT. We assessed flexor digitorum superficialis (FDS) tendon and adjacent SSCT displacements with colour Doppler ultrasound as 16 healthy participants completed long finger flexion/extension movements captured by a motion capture system. FDS tendon displacements fit a second-order regression model based on metacarpophalangeal and proximal interphalangeal joint flexion angles (R2 = 0.92 ± 0.01). SSCT displacements were 33.6 ± 1.7% smaller than FDS tendon displacements and also fit a second-order regression model (R2 = 0.89 ± 0.01). FDS tendon and SSCT displacement both correlated with finger joint thickness, enabling participant-specific anthropometric scaling. We propose the current regression models as an ergonomic method to determine relative displacements between the finger flexor tendons and SSCT.

The Snow-Fink technique as an opposition tendon transfer for children born with a hypoplastic or absent thumb.

A novel opposition tendon transfer, previously described by Snow and Fink in adults but not in children, can provide better functional results and cosmetic appearance than the currently preferred Huber transfer. Thirty-one children were born either without a thumb (17) or with a hypoplastic thumb (14). Thirty-eight thumbs were classified according to the Blauth classification as stages II, IIIA, IIIB, IV, and V respectively. The opposition tendon transfer was performed between the ages of 4 and 10, using the expendable flexor digitorum superficialis (FDS) tendon from the ring finger which was passed through a 3-mm-diameter window in the transverse carpal ligament, routed subcutaneously across the palm and attached to the insertion of the abductor pollicis brevis on the base of the proximal phalanx of the thumb. This creates a vector of pull from the ulnar side of the hand which both abducts and pronates the thumb. Twenty-one hands underwent additional procedures such as four-flap Z-plasty (11), ulnar collateral ligament reconstruction (6), joint transfer, full-thickness skin grafting, and distraction lengthening. The ability of each child to oppose their thumb to the index finger (score 2), middle finger (score 3), ring finger (score 4), or small finger (score 5) was assessed preoperatively and postoperatively by their Kapandji score. Thirty-one children (81.6%) achieved a postoperative Kapandji score of 5, while 7 children (18.4%) had a postoperative Kapandji score of 4. No deformities were observed, and the metacarpophalangeal (MCP) joint was stabilized with the other slip of the FDS when necessary. An opposition transfer using the FDS tendon of the ring finger through a window in the transverse carpal ligament is a simple and reliable technique for improving thumb function in children born with an absent or hypoplastic thumb. This transfer does not produce a concave deformity in the hypothenar eminence like the Huber transfer, provides better pronation, and affords concurrent stabilization of the MCP joint.

Justification of the Topical Use of Pharmacological Agents on Reduce of Tendon Adhesion after Surgical Repair

Tendon injuries are the second most common hand injuries in orthopedic patients. Tendon adhesions are one of the most concerning complications after surgical repair of the flexor tendon injury, particularly in zone II, which extends from the A1 pulley to the distal insertion of the Flexor Digitorum Superficialis (FDS) tendon in the finger [1,2].

Anatomic variation of palmaris longus and flexor digitorum superficialis of little finger in Indian population.

Introduction: Palmaris longus and flexor digitorum superficialis of the little finger are highly variable anatomically. The tendons vary in different parts of the globe and different regions of the same country. Many studies have negated an association between the tendons. However, most of the studies have a sample size of less than 500 subjects. Aims and objectives: The aim was to study the tendons in the Indian population and study the association, if any between the tendons and to test functional significance of the tendons using the Michigan Hand Outcomes Questionnaire. Methods and material: It was a single centre cross-sectional study with a sample size of 1500 in the age group of 20–60 years. The subjects were tested for the presence of the tendons and their functionality was assessed by Michigan Hand Outcomes Questionnaire. The data was tabulated and was assessed using SPSS 13.0 software. Results: Palmaris longus was bilaterally absent in 10.9% and flexor digitorum superficialis of the little finger was bilaterally absent in 42% of the cases. There was a statistically significant association between the tendons when considered bilaterally. The tendons did not have any bearing on the functionality as assessed by the Michigan Hand Outcomes Questionnaire. Conclusions: There is significant variability in the palmaris longus and flexor digitorum superficialis tendon to the little finger not only in the different countries but in different regions of the same country. However despite the various clinical and medicolegal aspects concerning both the tendons, they do not have much bearing on the functionality of the hand.

Biomechanical risk factors and flexor tendon frictional work in the cadaveric carpal tunnel

Pathological changes in carpal tunnel syndrome patients include fibrosis and thickening of the subsynovial connective tissue (SSCT) adjacent to the flexor tendons in the carpal tunnel. These clinical findings suggest an etiology of excessive shear-strain force between the tendon and SSCT, underscoring the need to assess tendon gliding characteristics representative of repetitive and forceful work. A mechanical actuator moved the middle finger flexor digitorum superficialis tendon proximally and distally in eight fresh frozen cadaver arms. Eighteen experimental conditions tested the effects of three well-established biomechanical predictors of injury, including a combination of two wrist postures (0° and 30° flexion), three tendon velocities (50, 100, 150mm/sec), and three forces (10, 20, 40N). Tendon gliding resistance was determined with two light-weight load cells, and integrated over tendon displacement to represent tendon frictional work. During proximal tendon displacement, frictional work increased with tendon velocity (58.0% from 50–150mm/sec). There was a significant interaction between wrist posture and tendon force. In wrist flexion, frictional work increased 93.0% between tendon forces of 10 and 40N. In the neutral wrist posture, frictional work only increased 33.5% (from 10–40N). During distal tendon displacement, there was a similar multiplicative interaction on tendon frictional work. Concurrent exposure to multiple biomechanical work factors markedly increased tendon frictional work, thus providing a plausible link to the pathogenesis of work-related carpal tunnel syndrome. Additionally, our study provides the conceptual basis to evaluate injury risk, including the multiplicative repercussions of combined physical exposures.