Finger Flexor Digitorum Superficialis Tendon Research Articles

Isolated Closed Rupture of the Middle Finger Flexor Digitorum Superficialis Tendon in a Climber.

Isolated Closed Rupture of the Middle Finger Flexor Digitorum Superficialis Tendon in a Climber.

Sinestre, deviance, or biology? An investigation of hand dominance in relation to tendon absence.

The present study aimed to examine the relationship between hand dominance and the presence or absence of the flexor digitorum superficialis (FDS) in the fifth digit to add to the current body of knowledge. We hypothesized that the absence of the FDS in the right small finger is more prevalent in left-handed individuals. This was a prospective study conducted from January 2020 to April 2021 and performed at the plastic surgery department of a university hospital. The sample consisted of volunteers with no history of upper limb trauma, surgery, or any other condition. The study included male and female individuals over 18 years old at a local Rhode Island university campus. The FDS tendons of the bilateral fifth fingers were evaluated through clinical testing by an independent examiner. A total of 236 hands from 118 volunteers were analyzed. Left-hand dominant participants composed of 5% of the population. For these participants, the prevalence of absence of the fifth finger FDS tendon in the right hand was significantly higher than that of right-hand dominant participants (71.4% vs. 28.8%). No significant difference between sex assigned at birth (male vs. female) was noted and the absence of the FDS in either hand, regardless of hand dominance. The results from the current study demonstrate that anatomy may contribute to one's preference for left-handedness. For children who have difficulty using their right hand, perhaps, an assessment of their FDS status may result in earlier acceptance of using their left hand.

Carpal tunnel syndrome treatment and the subsequent alterations in tendon and connective tissue dynamics

BackgroundCarpal tunnel syndrome patients demonstrate diminished motion of the median nerve and fibrotic changes in the subsynovial connective tissue within the carpal tunnel. Currently, there are few prognostic factors to help predict the outcome of commonly performed treatments including surgical carpal tunnel release and corticosteroid injections. This study aimed to non-invasively assess the changes in the dynamic response of the subsynovial tissue relative to tendon motion after the intervention and to correlate this with disease severity. MethodsA total of 145 patients with carpal tunnel syndrome were recruited into this study. Clinical and demographic data, electrophysiological severity and dynamic ultrasound images were collected before and after treatment, either by injection or surgery. The relative motion of the subsynovial tissue with the underlying middle finger flexor digitorum superficialis tendon was measured using a speckle tracking algorithm and was expressed as a shear index (SI). Baseline and follow-up data, the association between change in SI and severity, and the role of treatment modality were analyzed and statistically compared. FindingsOverall, there was a significant increase (more relative motion) after treatment in the mean shear index from 79.9% (±15.4% SD) to 82.9% (±14.8% SD) (p = 0.03). Secondary analyses showed that this change was mostly present in those with mild disease severity undergoing surgery (p = 0.01). InterpretationThis study shows that the relative subsynovial tissue movement increases in patients after intervention. The present study lays a foundation for future studies to non-invasively assess the role of carpal tunnel dynamics in response to treatment.

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.

Carpal tunnel syndrome secondary to an accessory flexor digitorum superficialis muscle belly: case report and review of the literature.

Anomalous muscles usually do not cause symptoms but are of academic interest mainly discovered during cadaveric dissection. An aberrant muscle belly arising from the index finger flexor digitorum superficialis tendon causing carpal tunnel syndrome is rare. The management of such an anatomical variant is dependent on whether the median nerve compression is associated with a palpable mass. A brief case highlighting important management principles along with a complete literature review is reported.

Speckle-Tracking Sonographic Assessment of Longitudinal Motion of the Flexor Tendon and Subsynovial Tissue in Carpal Tunnel Syndrome

The aim of this study was to image both tendon and subsynovial connective tissue movement in patients with carpal tunnel syndrome and healthy control volunteers, using sonography with speckle tracking. To estimate accuracy of this tracking method, we used in vivo measurements during surgery to validate the motion estimated with sonography. We recruited 22 healthy volunteers and 18 patients with carpal tunnel syndrome. Longitudinal sonograms of the middle finger flexor digitorum superficialis tendon and subsynovial connective tissue were obtained during finger flexion and extension. The images were analyzed with a speckle-tracking algorithm. The ratio of the subsynovial connective tissue velocity to tendon velocity was calculated as the maximum velocity ratio, and the shear index, the ratio of tendon to subsynovial connective tissue motion, was calculated. For validation, we recorded flexor digitorum superficialis tendon motion during open carpal tunnel release. The shear index was higher in patients than controls (P < .05), whereas the maximum velocity ratio in extension was lower in patients than controls (P < .05). We found good intraclass correlation coefficients (>0.08) for shear index and maximum velocity ratio measurements between speckle-tracking and in vivo measurements. Bland-Altman analyses showed that all measurements remained within the limits of agreement. Speckle tracking is a potentially useful method to assess the biomechanics within the carpal tunnel and to distinguish between healthy individuals and patients with carpal tunnel syndrome. This method, however, needs to be further developed for clinical use, with the shear index and maximum velocity ratio as possible differentiating parameters between patients with carpal tunnel syndrome and healthy individuals.

Velocity‐dependent changes in the relative motion of the subsynovial connective tissue in the human carpal tunnel

The purpose of this study was to measure the rate-dependent changes in the relative motion of subsynovial connective tissue (SSCT) and median nerve in the human carpal tunnel. Using fluoroscopy, we measured the relative motion of middle finger flexor digitorum superficialis tendon, SSCT, and median nerve in eight human cadavers during simulated active finger flexion motions at 2.0, 5.0, 7.5, and 10.0 mm/s. The shear index was defined as the difference in motion between tendon and SSCT or tendon and nerve, expressed as a percentage of tendon excursion. The motion patterns of the SSCT and median nerve relative to tendon excursion were measured at each 10% increment (decile) of maximum tendon excursion. The tendon-SSCT shear index was significantly higher at 10.0 mm/s than at 2.0 mm/s in the single-digit motion. There were corresponding significant decreases in SSCT and median nerve motion for the 10.0 mm/s velocity compared to the 2.0 mm/s velocity. This study demonstrates that the relative motion of the tissues in the carpal tunnel appears to be dependent on tendon velocity, specifically with less nerve and SSCT motion at higher velocity tendon motion. This suggests that SSCT may be predisposed to shear injury from high-velocity tendon motion.

Gliding resistance of flexor tendon associated with carpal tunnel pressure: a biomechanical cadaver study.

The purpose of this study was to investigate the effect of carpal tunnel pressure on the gliding characteristics of flexor tendons within the carpal tunnel. Eight fresh human cadaver wrists and hands were used. A balloon was inserted into the carpal tunnel to elevate the pressure. The mean gliding resistance of the middle finger flexor digitorum superficialis tendon was measured with the following six conditions: (1) as a baseline, before balloon insertion; (2) balloon with 0 mmHg pressure; (3) 30 mmHg; (4) 60 mmHg; (5) 90 mmHg; (6) 120 mmHg. The gliding resistance of flexor tendon gradually increased as the carpal tunnel pressure was elevated. At pressures above 60 mmHg, the increase in gliding resistance became significant compared to the baseline condition. This study helps us to understand the relationship between carpal tunnel pressure, which is elevated in the patient with carpal tunnel syndrome (CTS) and tendon gliding resistance, which is a component of the work of flexion. These findings suggest that patients with CTS may have to expend more energy to accomplish specific motions, which may in turn affect symptoms of hand pain, weakness and fatigue, seen commonly in such patients.

Shear Strain and Motion of the Subsynovial Connective Tissue and Median Nerve During Single-Digit Motion

The objective of this study was to measure the relative motion of the middle finger flexor digitorum superficialis (FDS) tendon, its adjacent subsynovial connective tissue (SSCT), and the median nerve during single-digit motion within the carpal tunnel in human cadaver specimens and to estimate the relative motions of these structures in different wrist positions. Using fluoroscopy during simulated single-digit flexion, we measured the relative motion of the middle finger FDS tendon, SSCT, and median nerve within the carpal tunnel in 12 human cadavers. Measurements were obtained for 3 wrist positions: neutral, 60 degrees flexion, and 60 degrees extension. After testing with an intact carpal tunnel was completed, the flexor retinaculum was cut with a scalpel, and the same testing procedure was repeated for each wrist position. The relative motions of the tendon, SSCT, and median nerve were compared using a shear index, defined as the ratio of the difference in motion along the direction of tendon excursion between 2 tissues divided by tendon excursion, expressed as a percentage. Both tendon-SSCT and tendon-nerve shear index were significantly higher in the 60 degrees of wrist flexion and extension positions than in the neutral position. After division of the flexor retinaculum, the shear index in the 60 degrees wrist extension position remained significantly different from that of the neutral position. We have found that the relative motion between a tendon and SSCT in the carpal tunnel is maximal at extremes of wrist motion. These positions may predispose the SSCT to shear injury.

Effects of carpal tunnel release on the relative motion of tendon, nerve, and subsynovial connective tissue in a human cadaver model

Background The purpose of this study was to evaluate the effect of flexor retinaculum division (simulated carpal tunnel release) on the relative motion of flexor tendon, subsynovial connective tissue, and median nerve in human cadaver specimens. Methods Using fluoroscopy, we measured the relative motion of middle finger flexor digitorum superficialis tendon, subsynovial connective tissue, and median nerve in twelve human cadavers with simulated fist motion. Measurements were obtained for three wrist positions: neutral; 60° flexion; and 60° extension. The shear index was defined as the difference in motion between two tissues (tendon, subsynovial connective tissue, or nerve) relative to tendon excursion, expressed as a percentage. After testing with an intact carpal tunnel, the flexor retinaculum was cut and the testing procedure was repeated. Findings With an intact flexor retinaculum, the wrist flexion position showed significantly less displacement for the subsynovial connective tissue and median nerve relative to tendon displacement, and thus the highest potential shear strain between subsynovial connective tissue–tendon, and tendon–nerve. The wrist extension position also had a significantly higher potential shear strain for tendon–nerve compared to the neutral position. After division of the flexor retinaculum, the differences in shear index among wrist positions were reduced. For the wrist flexion position, the subsynovial connective tissue and median nerve displacements significantly increased, indicating lower shear index values. Interpretation These findings suggest that division of flexor retinaculum reduces the potential shear strain and thus possibly the risk of shear injury to tissues with the carpal tunnel.

Atypical Triggering at the Wrist Due to Intratendinous Infiltration of Tophaceous Gout

This is a report of a 41-year-old male with triggering of the long finger flexor digitorum superficialis tendon at the wrist secondary to tophaceous gout. The tophus was severely infiltrating the tendon, and a tenotomy of the FDS tendon was performed. Preoperatively, the lesion could not be distinguished from a neoplasm.

Relative Longitudinal Motion of the Finger Flexors, Subsynovial Connective Tissue, and Median Nerve Before and After Carpal Tunnel Release in a Human Cadaver Model

The normal gliding environment in the carpal tunnel is complex. The median nerve and flexor tendons are surrounded by a multilayered subsynovial tissue. To date, observations of the relative motions of the flexor tendon, median nerve and multilayered subsynovial tissue have been through a surgically released open carpal tunnel. The purpose of this study was to compare the motions of these tissues in an intact and open carpal tunnel. We measured the relative motion of the middle finger flexor digitorum superficialis tendon, its surrounding subsynovial connective tissue (SSCT) and the median nerve in 8 human cadavers. The flexor retinaculum was used as a fixed reference point. The motions were compared for simulated isolated middle finger and simulated fist motion as measured fluoroscopically in the closed carpal tunnel and directly in the open carpal tunnel. While the simulated isolated finger motion produced significantly less SSCT and median nerve motion (p<.05), there was no difference in flexor digitorum superficialis, SSCT, or nerve motion when comparing the fluoroscopic measurements in the closed carpal tunnel with the direct visual measurements in the open carpal tunnel. Relative motion of the flexor tendons, SSCT, and median nerve within the carpal tunnel follows a certain pattern, which may indicate the physiological state of the SSCT. This relative motion pattern was not affected by flexor retinaculum release.

Detection of Differential Gliding Characteristics of the Flexor Digitorum Superficialis Tendon and Subsynovial Connective Tissue Using Color Doppler Sonographic Imaging

The subsynovial connective tissue (SSCT) is the most characteristic structure in the carpal tunnel and is substantially affected in cases of carpal tunnel syndrome. We investigated the usefulness of Doppler sonography for measuring velocity differences between the flexor tendon and its associated SSCT in the carpal tunnel of cadaver hands. Six human cadaver wrists were used in this study (mean age of death, 82.2 years). The velocity difference between the middle finger flexor digitorum superficialis tendon and its corresponding SSCT was measured on a sonography machine equipped with a fingertip 13-MHz linear probe. At tendon velocities of greater than 2.5 cm/s, the tendon velocity was significantly greater than the SSCT velocity (P < .05). At less than 2.5 cm/s, there was no significant difference between tendon and SSCT velocities. Color Doppler imaging can identify and track SSCT motion separately from that of its associated tendons. Analysis of SSCT motion characteristics by color Doppler imaging may be useful for studying its function clinically.

Gliding characteristics between flexor tendons and surrounding tissues in the carpal tunnel: A biomechanical cadaver study

The purpose of this study was to investigate the gliding characteristics of flexor tendons within the carpal tunnel with varied wrist positions and tendon motion styles, which may help us to understand the relationship between carpal tunnel syndrome (CTS) and repetitive hand motion. Eight fresh human cadaveric wrists and hands were used. The peak (PGR) and mean (MGR) gliding resistance of the middle finger flexor digitorum superficialis tendon were measured with the wrist in 0, 30, and 60 degrees of flexion and extension. While moving all three fingers together, the PGR at 60 degrees flexion was significantly higher than that at 0, 30, or 60 degrees extension. While moving the middle finger alone, the PGR at 60 and 30 degrees flexion was significantly higher than the PGR at 60 degrees extension. The PGR moving the middle finger FDS alone was significantly greater than that for all three digits moving together in 0, 30, and 60 degrees flexion. Differential finger motion with wrist flexion elevated the tendon gliding resistance in the carpal tunnel, which may be relevant in considering the possible role of wrist position and activity in the etiology of CTS.

Entrapment of the flexor digitorum superficials in the radius fracture site

Entrapment of the flexor tendon after fracture of both forearm bones is very rare. This report describes entrapment of the middle finger flexor digitorum superficialis (FDS) tendon alone in the radius fracture site. A 13-year-old boy fractured both forearms and had closed reduction and a long-arm cast. After the cast was removed he had full middle finger motion with the wrist flexed but was unable to extend the proximal interphalangeal or metacarpophalangeal joints and could extend only the distal interphalangeal joint of the middle finger with the wrist in the neutral or extension position. Entrapment of the middle finger FDS tendon was suspected. After surgical release of the FDS tendon at the fracture site the patient had good functional results.

Ulnar nerve compression following flexor digitorum superficialis tendon transfers around the ulnar border of the forearm to restore digital extension: Case report

This case report describes a complication that occurred following long and ring finger flexor digitorum superficialis tendon transfers routed around the ulnar border of the forearm to restore digital extension. An ulnar mononeuropathy developed in the early postoperative period that was characterized by decreased ring and small finger sensation and interosseous muscle weakness. Operative exploration demonstrated extrinsic compression of the ulnar nerve by the long and ring finger flexor digitorum superficialis tendons. When superficialis tendon transfers are chosen to restore digital extension, passage around the radial side of the forearm or through the interosseous space are recommended to avoid this potential complication.