Tendon Excursion Research Articles

Division of the Transverse Carpal Ligament and Flexor Tendon Excursion: Open and Endoscopic Carpal Tunnel Release

Ten fresh cadaver upper extremities from 10 different subjects were used in this study of the effect of both open and endoscopic carpal tunnel release on flexor tendon excursion. The amount of excursion necessary to bring each finger from the fully extended to the fully flexed position with the fingertip just touching the palm was measured with the extremity mounted in a device that moved the wrist from extension through flexion. Endoscopic carpal tunnel release, open release, and transverse carpal ligament reconstruction were performed with tendon excursion measurements made in each of four wrist positions after each procedure. Fingertip to palm distance was also measured. The measurements of flexor tendon excursion in neutral wrist position with intact transverse carpal ligament served as the norm for each finger and as the denominator in the ratio of postoperative to preoperative excursion distances. The study confirmed the importance of the transverse carpal ligament as a flexor pulley; transection of the ligament increased the amount of flexor tendon excursion necessary to achieve finger flexion and fingertip-to-palm contact. Tendon excursion/digital flexion improved after transposition flap repair. Neither open nor endoscopic carpal tunnel release conferred any particular benefit to flexor tendon excursion postoperatively. The proximal palmar aponeurosis does not seem to have the same pulley effect as the transverse fibers of the distal palm.

Tendon excursion measurements with colour doppler imaging: A calibration study on an embalmed human specimen

We assessed the applicability of tendon excursion measurement by means of Colour Doppler Imaging (CDI) on human specimens, and also assessed the correlation between values measured by Doppler and by displacement meters. Muscles were separately connected to a mass of 1 kg with a steel wire running over a pulley. This weight moved the telescopic end of a digital displacement meter up and down during passive extension and flexion of the fingers. Excursion was measured with a pulsed multi-channel CDI scanner on the same arm. Assessment of finger tendon excursion with CDI correlated well with the mechanical micro displacement meter, the latter being considered the most accurate method in cadaver studies.

Mechanical advantage of the thumb muscles

The purpose of this study was to measure the moment arms of four extrinsic muscles (flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus) and four intrinsic muscles (flexor pollicis brevis, abductor pollicis brevis, adductor pollicis, and opponents pollicis) of the thumb at the interphalangeal, the metacarpophalangeal, and the carpometacarpal joints in the same cadaver specimens and to examine the specific role of each muscle. Measurements were made on seven fresh frozen cadaver hands. The moment arms were measured during flexion/extension of the interphalangeal joint, flexion/extension and adduction/abduction of the metacarpophalangeal joint, and flexion/extension and adduction/abduction of the carpometacarpal joint. Moment arms were computed using the slope of the tendon excursion–joint angle relationship. The specific function of each muscle was determined by multiplying the measured moment arms by the maximum force that each muscle can generate. It was found that the flexor pollicis longus was a pure flexor while flexor pollicis brevis was an adductor as well as a flexor, the extensor pollicis longus was an extensor and an adductor, extensor pollicis brevis was an extensor and a mild abductor, the abductor pollicis longus was an extensor as well as an abductor, the abductor pollicis brevis was mainly an abductor, the adductor pollicis was a major flexor as well as an adductor, and the opponents pollicis was a flexor and an abductor.

Flexor digitorum profundus tendongrafting (intrasynovial donor tendons)

Traditional single- and two-stage tendon grafting methods for flexor tendon reconstruction have been unable toconsistently restore satisfactory digital flexion. Although multiple factors may affect the ultimate outcome, the role of the donor tendon graft has only recently been examined. Current methods of flexor tendon grafting for failed zone II tendon repairs and neglected flexor tendon lacerations involve the use of extrasynovial donor grafts. Clinical and histological studies have shown significant adhesion formation as a result of early cellular necrosis and peritendinous tissue ingrowth into the extrasynovial donor graft. The formation of these adhesions may result in poor tendon excursion and limited proximal interphalangeal joint rotation. Recent studies have shown that intrasynovial donor tendon grafts are incorporated to the native tendon site by a unique intrinsic mechanism of repair. Improved functional characteristics of increased tendon excursion and increased digital rotation are primarily caused by this paucity of adhesion formation and will hopefully result in improved overall patient outcomes.

Flexor tendon pulley reconstruction

The flexor tendon pulley mechanism causes the tendons to work with maximum efficiency. Without its competency,flexor tendons will bowstring causing significant losses of digital motion and strength. Without an intact pulley system, increased flexor tendon excursion is required to affect joint motion and flexion contractures may develop over time. Recent investigators have described the properties of the intact flexor pulley system as well as those of flexor pulley reconstructive techniques. Reconstruction of the flexor pulley system should take into account both strength and length of the construct and in most cases a loop of either flexor tendon graft or wrist extensor retinaculum is used. Other methods are available including the use of the palmar plate as well as the superficialis tendon.

The effects of proximal load on the excursion of autogenous flexor tendon grafts

To determine the relationship between the intrinsic properties of tendon and tendon excursion in 2 types of autogenous tendon grafts, hindpaw intrasynovial and extrasynovial tendons were transferred to the lateral and medial forepaws of adult mongrel dogs (16 experimental and 16 control tendons). After each digit was marked with radiopaque markers, it was placed in a specialized jig, and weights of 25 g, 100 g, or 200 g were applied to the flexor tendons. Specialized radiographs were obtained with the digit in flexion and extension. Tendon excursion and joint rotation were calculated. There were no statistically significant differences between experimental groups for tendon excursion or for joint angular rotation (p > .05). For intrasynovial tendon grafts, the angular rotation per millimeter tendon excursion was 10.9 degrees +/- 2.4 degrees/mm, 9.4 degrees +/- 1.2 degrees/mm, and 9.0 degrees +/- 1.4 degrees/mm with 25-g, 100-g, and 200-g loads, respectively. Comparisons between experimental groups revealed that a statistically significant difference could not be determined (p > .05). With varying proximal loads, both intrasynovial and extrasynovial grafts showed similar amounts of tendon excursion. Variations in proximal load did not significantly influence the amount of excursion within the range of loads tested. Based on these data, it appears that the difference in repair potential for these 2 types of tendon grafts is not related to a differential in the amount of tendon graft excursion following transfer to the synovial space.

Functional distal interphalangeal joint splinting for trigger finger in laborers: a review and cadaver investigation.

This two-part study evaluates the efficacy of functional distal interphalangeal joint (DIP) splinting for the treatment of trigger finger. Thirty-one fingers from 21 meat packing plant workers were treated with DIP splinting. A single corticosteroid injection was offered if triggering was stage 4 or greater. All workers returned to work immediately. Eighty-one percent of the digits were treated successfully (mean follow-up: 1 year). Treatment failure correlated with duration of symptoms and stage of triggering but did not correlate with age, race, sex, disease in multiple digits, or prior treatment. For the second part of the study, the effect of DIP splinting on flexor digitorum profundus (FDP) tendon excursion was studied in 16 fingers from 4 fresh cadavers. Excursion decreased 4.8 mm for the Stax splint and 4.2 mm for the dorsal Alumafoam splint. We conclude that DIP splinting provides a reliable and functional means of treating work-related trigger finger without lost time from work. Our cadaver investigation supports our theory that DIP splinting significantly decreases FDP excursion.

Surgical treatment of carpal tunnel syndrome and trigger digits in children with mucopolysaccharide storage disorders

The role of surgical intervention for carpal tunnel syndrome (CTS) and trigger digits in children with mucopolysaccharide storage disorders (MPSDs) has not been clearly defined, particularly as the treatment of the underlying disease has advanced to include bone marrow transplantation. This study reviews our experience in the treatment of CTS and trigger digits in 22 children with MPSDs who were evaluated for CTS by electromyographic (EMG)/nerve conduction velocity (NCV) testing. Seventeen children were diagnosed with CTS by EMG/NCV testing and were treated with bilateral open surgical release with or without flexor tenosynovectomy. The EMG/NCV testing revealed normal results in 5 patients who are subsequently being monitored. Forty-five digits in 8 children were diagnosed clinically with trigger digits. Nineteen digits were treated by annular pulley release alone. Twenty-six digits were treated by annular pulley release with partial flexor digitorum superficialis tendon resection. The average age at the time of hand surgery was 6.3 years, and at the time of follow-up, 9.6 years. Postoperative EMG/NCV testing in 7 children showed 1 with improvement and 6 with normalization. None of the patients undergoing carpal tunnel release went on to develop thenar atrophy or absent sensibility, as has been reported in untreated cases. Patients were evaluated for triggering digits both by preoperative tendon palpation and by intraoperative flexor tendon excursion at the time of open carpal tunnel release. All patients undergoing trigger release had improved active digital flexion seen at the final follow-up visit. Because of the very high incidence of CTS and trigger digits in this population, the authors currently recommend routine screening of EMG/NCV for all children with MPSDs. Early surgical intervention for nerve compression and stenosing flexor tenosynovitis can maximize hand function in these children.

The effects of multiple-strand suture methods on the strength and excusion of repaired intrasynovial flexor tendons: A biomechanical study in dogs

This study was designed to determine the effects of in vivo multistrand, multigrasp suture techniques on the strength and gliding of repaired intrasynovial tendons when controlled passive motion rehabilitation was used. Twenty-four adult mongrel dogs were divided into 4 groups and their medial and lateral forepaw flexor tendons were transsected and sutured by either the Savage, the Tajima, the Kessler, or the recently developed 8-strand suture method. The tendon excursion, joint rotation, and tensile properties of the repaired tendons were evaluated biomechanically at 3 and 6 weeks after surgery. It was found that neither time nor suture method significantly effected proximal and distal interphalangeal joint rotation or tendon excursion when the 4 techniques were compared to each other. Normalized load value (experimental/control) was significantly affected by both the suture method and the amount of time after surgery, however. The Savage and 8-strand repair methods had significantly greater strength than did the Tajima method at each time interval (p < .05 for each comparison). In addition, the 8-strand method had significantly greater normalized load values than did the Savage method at each time interval (p < .05 for each comparison). Normalized stiffness (experimental/control) for the 8-strand repair method was significantly greater than that for the Tajima and Savage methods at 3 and 6 weeks after surgery (p < .05). In addition, the normalized stiffness values for the 6-week groups was significantly greater than those for the 3-week groups (p < .05). It was concluded that the method of tendon suture was a significant variable insofar as the regaining of tendon strength was concerned and that the newer low-profile 8-strand repair method significantly expands the safety zone for the application of increased in vivo load during the early stages of rehabilitation.

Temporal changes in grip and pinch strength after open carpal tunnel release and the effect of ligament reconstruction

Symptoms of pain and weakness are nearly ubiquitous after carpal tunnel release. This study investigates the length of time before restoration of grip and pinch strength after open carpal tunnel release, in a population of patients without workers' compensation-related injuries. Two different forms of carpal ligament reconstruction were carried out in 2 groups of patients, and a third group underwent no ligament reconstruction. Grip and pinch strengths were measured for participants in each group both preoperatively and at set postoperative intervals. Mean changes in strength were calculated and analysis of variance used to determine statistical significance of the changes. Grip strength at 6 weeks after surgery in the group that underwent transposition flap repair exceeded preoperative grip strength values and all 3 groups surpassed preoperative grip strength measurements at 12 weeks. By 6 weeks after surgery, all pinch measurements for 3 groups equaled or exceeded preoperative pinch measurements. The transposition flap repair group recovered faster than did the other 2 groups and surpassed those groups in maximum grip and pinch strength at 12 weeks. These results suggest that transverse carpal ligament reconstruction, particularly the transposition flap technique, after open carpal tunnel release confers a mechanical advantage and that the transverse carpal ligament is an important pulley in flexor tendon excursion.

The Marshall R. Urist Young Investigator Award

To examine the hypothesis that different types of dense regular connective tissue may have different repair mechanisms within the synovial space, intrasynovial and extrasynovial autogenous donor flexor tendon grafts were placed within the synovial sheaths of the medial and lateral forepaw digits of dogs. Histologic, ultrastructural, biochemical, and biomechanical analyses were done between 10 days and 6 weeks after tendon grafting. Intrasynovial tendon grafts remained viable when transferred to the synovial space and appeared to heal through an intrinsic process with preservation of the gliding surface and improved functional characteristics. Extrasynovial tendon grafts functioned as a scaffolding for the early ingrowth of new vessels and cells. Early cellular necrosis consistently was followed by the ingrowth of fibrovascular adhesions from the periphery. The formation of dense peripheral adhesions, obliterating the gliding surface of the tendon, led to diminished tendon excursion and proximal interphalangeal joint rotation.

The effect of division of the transverse carpal ligament on flexor tendon excursion

The effect of the transverse carpal ligament (TCL) as a pulley was evaluated by measuring flexor tendon excursion after ligament division and by changing wrist position through a range of flexion and extension. Eight fresh cadaver upper extremities were mounted in a device and tendon excursions from full extension to fingertip-palm contact were measured for each flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendon. Measurements were performed with the wrist at 30 degrees extension, neutral, 30 degrees flexion, and 60 degrees flexion. The TCL was then sectioned, the skin was sutured, and the measurements were repeated. Two forms of carpal ligament repair were then done--transposition flap and aponeurotic repairs--and measurements were again repeated. With increasing wrist flexion, greater excursion differences were noted. Analysis of variance revealed that for both FDS and FDP, a significant difference in excursion occurred at 60 degrees wrist flexion and 30 degrees wrist extension with no ligament reconstruction or aponeurotic repair, compared to values prior to carpal tunnel release (p < .05) and to transposition ligament repair (p < .05).

The range of excursion of flexor tendons in zone V: a comparison of active vs passive flexion mobilisation regimes

A number of early postoperative mobilisation regimes have been developed in an attempt to increase tendon excursion and gliding and thereby reduce formation of adhesions following repair of flexor tendons. Early active flexion mobilisation regimes are becoming more popular, and have replaced early passive flexion regimes in many centres. The aim of the present study was: (a) to determine the range of excursion of flexor tendons in Zone V, and (b) to compare the excursion ranges between active (Belfast) and passive (modified Duran) flexion mobilisation regimes postoperatively. This was done (a) in two cadavers, and (b) in two patients intraoperatively, and postoperatively at 10 days, 3 weeks and 6 weeks. With passive flexion, the mean tendon excursion in Zone V in cadavers was 1 mm for flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) tendons respectively. With simulated active flexion, the mean tendon excursion was 14 mm, 10 mm and 11 mm respectively. The mean tendon excursion in clinical cases intraoperatively following passive flexion was 2 mm for FDS, FDP and FPL respectively; following simulated active flexion it was 10 mm, 11 mm and 11 mm for FDS, FDP and FPL respectively. On the tenth day following repair, the mean excursions of FDS, FDP and FPL were 1 mm, 4 mm and 4 mm on passive flexion as compared to 3 mm, 10 mm and 12 mm on active flexion respectively. Three weeks postoperatively, the mean excursions of FDS, FDP and FPL tendons were 1 mm, 2 mm and 1 mm on passive flexion as compared to 5 mm, 15 mm and 21 mm on active flexion respectively. Six weeks postoperatively, the mean excursions of FDS, FDP and FPL tendons were 9 mm, 7 mm and 4 mm on passive flexion as compared to 12 mm, 33 mm and 20 mm on active flexion respectively. These results demonstrate an increased excursion of repaired flexor tendons in Zone V following an active flexion mobilisation regime as compared to a passive flexion mobilisation regime.

Transverse carpal ligament: its effect on flexor tendon excursion, morphologic changes of the carpal canal, and on pinch and grip strengths after open carpal tunnel release.

A three-part study is described that examines postoperative weakness after open carpal tunnel release and investigates the role of the transverse carpal ligament in the digital flexor pulley system. The effect of this ligament on flexor tendon excursion is evaluated in a cadaver study. Magnetic resonance imaging analysis is used to determine whether division of the transverse carpal ligament promotes volar migration of the median nerve and flexor tendons. Finally, the effects of ligament division and various methods of transverse carpal ligament reconstruction on the return of grip and pinch strengths after open carpal tunnel release are evaluated. The authors were able to determine that transverse carpal ligament reconstruction, particularly the transposition flap repair technique, after open carpal tunnel release confers a mechanical advantage and that the transverse carpal ligament is an important pulley for flexor tendon excursion. Based on the magnetic resonance imaging studies, volar displacement of carpal contents is reduced in patients undergoing transverse carpal ligament reconstruction by means of a transposition flap compared with those undergoing no ligament reconstruction and those undergoing reconstruction using the palmar aponeurosis. Postoperative grip and pinch strength values for the transposition flap repair group surpassed those of the other two groups at 12 weeks.

Scapholunate interosseous ligament sectioning adversely affects excursions of radial wrist extensor and flexor tendons

Excursions of tendons around the scaphoid were measured in 6 fresh cadaver forearms to evaluate the role of the scapholunate interosseous ligament (SLIL) in wrist joint motion. Excursions of the extensor carpi radialis longus (ECRL) and brevis (ECRB) tendons and the flexor carpi radialis (FCR) tendon were continuously recorded during wrist flexion, extension, and radial and ulnar deviation. Tendon excursions were measured in the intact wrists and after complete sectioning of the SLIL. Tendon excursions were altered significantly in the major ranges of wrist motion after SLIL sectioning. After ligament sectioning, excursions of the ECRL and ECRB tendons increased significantly in wrist flexion and extension. Excursions of the FCR tendon increased significantly during wrist extension and ulnar deviation. These findings support the concepts that integrity of the SLIL plays an important role in wrist function and that injury of the ligament may cause clinical problems.

Displacement and strain of the median nerve at the wrist

Median nerve displacement and strain in the carpal tunnel region were measured as functions of wrist position and carpal tunnel pressure in 5 cadaver forearms during simulated active finger flexion. The positions of spherical stainless-steel markers embedded within the median nerve and flexor digitorum superficialis of the long finger were measured in 3 dimensions by a radiographic direct linear transformation technique. Each limb was tested in 3 wrist positions (60 degrees extension, neutral, and 60 degrees flexion) and 4 carpal tunnel pressures (0, 30, 60, and 90 mmHg). Carpal tunnel pressure was controlled with a balloon angiocatheter inserted deep to the flexor digitorum profundus. The ratio of median nerve to flexor tendon excursion was linear and was affected by wrist position but not carpal tunnel pressure. Patterns of strain in the median nerve proximal to the flexor retinaculum were different from those of strain within the carpal tunnel. Nerve strains were affected by wrist position, but carpal tunnel pressure had no effect. The hydrostatic pressure effect associated with carpal tunnel syndrome does not appear to influence median nerve kinetics or kinematics for the wrist positions studied.

Effect of radial shortening on muscle length and moment arms of the wrist flexors and extensors.

The purpose of this study was to determine the effect of distal radial shortening on muscle length and moment arm of the wrist flexors and extensors. In eight cadaveric upper extremities, distal radius fractures were simulated by an ostectomy. The distal radius was progressively shortened by 2.5, 5.0, 7.5, and 10 mm. Changes in the resting length of the flexor carpi radialis and ulnaris, extensor carpi radialis longus and brevis, and extensor carpi ulnaris muscles were measured with rotary potentiometers at neutral position, flexion, extension, and radial and ulnar deviation of the wrists. The wrists were passively moved through flexion-extension and radioulnar deviation, and tendon excursions and wrist joint angulation were recorded simultaneously. Tendon moment arms were derived from tendon excursions and joint motion. The results showed that either muscle length or moment arm of the principal wrist flexors and extensors was significantly affected by the radial shortening. Muscle length decreased significantly after radial shortening in all the wrist flexors and extensors except for the extensor carpi ulnaris. The moment arm of the extensor carpi ulnaris tendon decreased significantly during either wrist flexion-extension or radioulnar deviation. The extensor carpi radialis brevis and flexor carpi ulnaris tendons also showed a significant decrease in their moment arms during radioulnar deviation of the wrist. Radial shortening of only 2.5 mm caused statistically significant changes in muscle length and moment arm of the wrist flexors and extensors. Increasing the extent of radial shortening exaggerated the biomechanical changes in the wrist motors. These results validate the importance of normal radial length for wrist kinetics and, from a biomechanical perspective, support complete correction of radial shortening after distal radius fractures.

Comparison of two methods for computing abduction moment arms of the rotator cuff

Biomechanical models of the shoulder mechanism require estimates of muscle moment arm magnitude. Some shoulder models have estimated muscle moment arms by assuming an idealized minimum distance path from the origin to insertion that passes around the bony geometry. Alternatively, the principle of virtual work can be used to estimate moment arms from tendon excursion and joint-angle data. The purpose of this study was to determine if these two methods give different estimates of abduction moment arms for the supraspinatus, infraspinatus, and subscapularis muscles. Muscle moment arms were estimated for these muscles on ten fresh frozen cadaver specimens. The results showed a significant difference between the two estimation methods. Average differences were 3.1 mm (10.6%), 3.9 mm (43.9%), and 7.2 mm (70.3%) for the supraspinatus, subscapularis, and infraspinatus muscles, respectively. These results suggest that shoulder models based on the origin-insertion method may give higher rotator cuff muscle force estimates than methods using the slope of the tendon excursion vs joint angle relationship.

Metacarpal Fracture Angulation Decreases Flexor Mechanical Efficiency in Human Hands

The most common fracture of the hand occurs at the neck of the metacarpal. Despite clinical studies, controversy remains as to how much fracture angulation should be tolerated before more aggressive reduction is required. A controlled biomechanical model was used to simulate fifth metacarpal head fractures in fresh human cadaveric hands. Fracture angulation was varied from 0 to 90 degrees at 10-degree intervals. We measured tendon excursion, tendon load, and work required to flex the small finger from full extension to full flexion with 10-degree incremental increases in vertex-dorsal angulation. Repeated measures analysis of variance revealed a significant decay in the efficiency of the flexor system when fracture angulation exceeded 30 degrees. Tendon excursion, load, and work requirements were all increased, confirming the detrimental effect of excessive fracture angulation on hand mechanics and function.

Rehabilitation after fractures of the hand

Rehabilitation after a hand fracture begins during the early phases of fracture healing and continues until skeletalintegrity and hand function are restored. The rehabilitation plan is tailored according to the stage of healing. The emphasis of therapy during the early reparative stage of healing is on edema control, pain management, preservation of motion at the uninvolved joints, protective splinting and positioning to prevent disruption of fracture healing, and to prevent joint contracture. The next phase of therapy begins when clinical healing is present and emphasizes the active mobilization of the joints immediately adjacent to the fracture that were incorporated in the cast or splint. Tendon gliding exercises are also stressed at this time to restore flexor and extensor tendon excursion. The final phase of therapy begins when the fracture is well healed. The focus of therapy at this time is the development of strength and hand function and the resumption of activities of daily living and work tasks. General rehabilitation techniques appropriate for all hand fractures include positioning and splinting, edema and pain control, joint and soft tissue mobilization techniques, and tendon gliding and strengthening exercises.