Tendon Excursion Research Articles

Delineation of the mechanisms of tendon gliding resistance within the carpal tunnel

BackgroundForceful, high-velocity, and repetitive manual hand tasks contribute to the onset of carpal tunnel syndrome. This study aimed to isolate and identify mechanisms that contribute to tendon gliding resistance in the carpal tunnel. MethodsEight human cadaver hands (four pairs) were used. Tendon gliding resistance (force, energy, and stiffness) was measured under different conditions: with intact and with divided subsynovial connective tissue, at 2mm/s and 60mm/s tendon excursion velocity, and with and without relaxation time before tendon excursion. ResultsSubsynovial connective tissue stretching substantially contributed to increased gliding resistance force and energy during higher tendon excursion velocities, and subsynovial connective tissue stiffening was observed. Poroelastic properties of the tendon (and possibly the subsynovial connective tissue) also appear to be involved because relaxation time significantly increased gliding resistance force and energy (P<0.01), and the difference in energy and force between high- and low-velocity tendon excursions increased with relaxation time (P=0.01 and P<0.01). Lastly, without relaxation time, no difference in force and energy was observed (P=0.06 and P=0.60), suggesting contact friction. InterpretationThese findings are consistent with the hypothesis that the mechanics of tendon motion within the carpal tunnel are affected by the integrity of the subsynovial connective tissue. While not tested here, in carpal tunnel syndrome this tissue is known to be the fibrotic, thickened, and less-fluid-permeable. An extrapolation of our findings suggests that these changes in the subsynovial connective tissue of carpal tunnel syndrome patients could increase contact friction and carpal tunnel pressure.

Comparison of the Achilles tendon moment arms determined using the tendon excursion and three-dimensional methods

The moment arm of muscle‐tendon force is a key parameter for calculating muscle and tendon properties. The tendon excursion method was used for determining the Achilles tendon moment arm (ATMA). However, the accuracy of this method remains unclear. This study aimed to investigate the magnitude of error introduced in determining the ATMA using the tendon excursion method by comparing it with the reference three‐dimensional (3D) method. The tendon excursion method determined the ATMA as the ratio between the Achilles tendon displacement during foot rotation from 15° of dorsiflexion to 15° of plantarflexion and the joint rotation angle. A series of foot images was obtained at 15° of dorsiflexion, the neutral position, and 15° of plantarflexion. The 3D value of the ATMA was determined as the shortest distance between the talocrural joint axis and the line of action of the Achilles tendon force. The ATMA determined by the tendon excursion method was smaller by 3.8 mm than that determined using the 3D method. This error may be explained mainly by the length change in the Achilles tendon due to the change in the force applied to it, as passive plantarflexion torque was different by 11 Nm between 15° of dorsiflexion and 15° of plantarflexion. Furthermore, the ATMAs determined using the 3D and tendon excursion methods were significantly correlated but the coefficient of determination was not large (R 2 = 0.352). This result suggests that the tendon excursion method may not be feasible to evaluate the individual variability of the ATMA.

The effect of mesenchymal stromal cell sheets on the inflammatory stage of flexor tendon healing.

BackgroundThe clinical outcomes following intrasynovial flexor tendon repair are highly variable. Excessive inflammation is a principal factor underlying the formation of adhesions at the repair surface and affecting matrix regeneration at the repair center that limit tendon excursion and impair tendon healing. A previous in-vitro study revealed that adipose-derived mesenchymal stromal cells (ASCs) modulate tendon fibroblast response to macrophage-induced inflammation. The goal of the current study was therefore to explore the effectiveness of autologous ASCs on the inflammatory stage of intrasynovial tendon healing in vivo using a clinically relevant animal model.MethodsZone II flexor tendon transections and suture repairs were performed in a canine model. Autologous ASC sheets were delivered to the surface of repaired tendons. Seven days after repair, the effects of ASCs on tendon healing, with a focus on the inflammatory response, were evaluated using gene expression assays, immunostaining, and histological assessments.ResultsASCs delivered via the cell sheet infiltrated the host tendon, including the repair surface and the space between the tendon ends, as viewed histologically by tracking GFP-expressing ASCs. Gene expression results demonstrated that ASCs promoted a regenerative/anti-inflammatory M2 macrophage phenotype and regulated tendon matrix remodeling. Specifically, there were significant increases in M2-stimulator (IL-4), marker (CD163 and MRC1), and effector (VEGF) gene expression in ASC-sheet treated tendons compared with nontreated tendons. When examining changes in extracellular matrix expression, tendon injury caused a significant increase in scar-associated COL3A1 expression and reductions in COL2A1 and ACAN expression. The ASC treatment effectively counteracted these changes, returning the expression levels of these genes closer to normal. Immunostaining further confirmed that ASC treatment increased CD163+ M2 cells in the repaired tendons and suppressed cell apoptosis at the repair site.ConclusionsThis study provides a novel approach for delivering ASCs with outcomes indicating potential for substantial modulation of the inflammatory environment and enhancement of tendon healing after flexor tendon repair.

Relationship Between Juncturae Tendinum and Sagittal Bands.

The juncturae tendinum and sagittal bands transmit precise forces through the dorsum of the hand. Both structures are integral in the mechanics of normal digital extension and in stabilization of the metacarpophalangeal (MCP) joints. Extensor tendon injury, or rupture/attenuation of sagittal bands and/or juncturae tendinum, may disrupt the kinematic chain and lead to a number of abnormal hand postures and motions. Early treatment of extensor tendon and/or sagittal band injury is dependent upon proper recognition of primary pathology. Proper evaluation and the use of special clinical tests should be implemented to rule out other pathologies. Once diagnosed, treatment may consist of relative motion splinting and standard pain/edema control measures to increase joint motion, tendon excursion, and functional use of the hand.

Differences in Pedaling Technique in Cycling: A Cluster Analysis.

To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (POVT2) compared with cycling at their maximal power output (POMAX). Twenty athletes performed an incremental cycling test to determine their power output (POMAX and POVT2; first session), and pedal forces, muscle activation, muscle-tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in POMAX and POVT2. Athletes were assigned to 2 clusters based on the behavior of outcome variables at POVT2 and POMAX using cluster analysis. Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle-tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at POVT2 vs POMAX, cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length. Increases in power output lead to greater variations in knee angle, muscle-tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.

Assessing Finger Joint Biomechanics by Applying Equal Force to Flexor Tendons In Vitro Using a Novel Simultaneous Approach.

BackgroundThe flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are critical for finger flexion. Although research has recently focused on these tendons’ coactivity, their contributions in different tasks remain unclear. This study created a novel simultaneous approach to investigate the coactivity between the tendons and to clarify their contributions in different tasks.MethodsTen human cadaveric hands were mounted on our custom frame with the FDS and FDP of the third finger looped through a mechanical pulley connected to a force transducer. Joint range of motion, tendon excursion and loading force were recorded during individual joint motion and free joint movement from rest to maximal flexion. Each flexor tendon’s moment arm was then calculated.ResultsIn individual motions, we found that the FDP contributed more than the FDS in proximal interphalangeal (PIP) joint motion, with an overall slope of 1.34 and all FDP-to-FDS excursion (P/S) ratios greater than 1.0 with force increase. However, the FDP contributed less than the FDS in metacarpophalangeal (MCP) joint motion, with an overall slope of 0.95 and P/S ratios smaller than 1.0 throughout the whole motion except between 1.9% and 13.1% force. In free joint movement, the FDP played a greater role than the FDS, with an overall ratio of 1.37 and all P/S ratios greater than 1.0.ConclusionsThe new findings include differences in finger performance and excursion amounts between the FDS and FDP throughout flexion. Such findings may provide the basis for new hand models and treatments.

Vector-based forearm rotation moment arms – A sensitivity analysis

All existing moment arm data for muscles of the forearm derive from tendon excursion experiments. Moment arms determined this way are only valid for movement about the same generalised coordinate system as was used during the tendon excursion, which makes their implementation in more complex or realistic joint models problematic. This study used a vector-based method to calculate muscle moment arms in a three dimensional model of forearm rotation. It also evaluated the sensitivity of this method to errors in the input data. There was reasonably close agreement between the moment arms calculated in this study and those published using tendon excursion methods. Six out of eight muscles had moment arms within the range of values reported previously. However, the vector-based method was sensitive to the accuracy of the input data. This sensitivity varied between muscles and input variables. Generally, the calculations were more robust to the point of force application than the muscle lines of action and the joint's axis of rotation. A small change in these variables could produce substantial changes in the calculated moment arms. Consequently, accurate input data is important when using the vector-based method in a joint model.

Use of a Lucas–Kanade-Based Template Tracking Algorithm to Examine In Vivo Tendon Excursion during Voluntary Contraction Using Ultrasonography

Ultrasound imaging can be used to study tendon movement during muscle contraction to estimate the tendon force–length relationship in vivo. Traditionally, such tendon displacement measurements are made manually (time consuming and subjective). Here we evaluated a Lucas–Kanade-based tracking algorithm with an optic flow extension that accounts for tendon movement characteristics between consecutive frames of an ultrasound image sequence. Eleven subjects performed 12 voluntary isometric plantar flexion contractions on a dynamometer. Simultaneously, the gastrocnemius medialis tendon was visualized via ultrasonography. Tendon displacement was estimated manually and by using two different automatic tracking algorithms. Maximal tendon elongation (manual: 17.9 ± 0.3 mm, automatic: 17.0 ± 0.3 mm) and tendon stiffness (209 ± 4 N/mm, 218 ± 5 N/mm) generated by the developed algorithm correlated with those obtained with the manual method (0.87 ≤ R ≤ 0.91), with no differences between methods. Our results suggest that optical flow methods can potentially be used for automatic estimation of tendon movement during contraction in ultrasound images, which is further improved by adding a penalty function.

Comparison of implant cost and surgical time in arthroscopic transosseous and transosseous equivalent rotator cuff repair

We investigated the cost savings associated with arthroscopic transosseous (anchorless) double-row rotator cuff repair compared with double-row anchored (transosseous-equivalent [TOE]) repair. All patients undergoing double-row arthroscopic rotator cuff repair from 2009 to 2012 by a single surgeon were eligible for inclusion. The study included 2 consecutive series of patients undergoing anchorless or TOE repair. Excluded from the study were revision repairs, subscapularis repairs, patients with poor tendon quality or excursion requiring medialized repair, and partial repairs. Rotator cuff implant costs (paid by the institution) and surgical times were compared between the 2 groups, controlling for rotator cuff tear size and additional procedures performed. The study included 344 patients, 178 with TOE repairs and 166 with anchorless repairs. Average implant cost for TOE repairs was $1014.10 ($813.00 for small, $946.67 for medium, $1104.56 for large, and $1507.29 for massive tears). This was significantly more expensive compared with anchorless repairs, which averaged $678.05 ($659.75 for small, $671.39 for medium, $695.55 for large, and $716.00 for massive tears). Average total operative time in TOE and anchorless groups was not significantly different (99 vs. 98 minutes). There was larger (although not statistically significant) case time variation in the TOE group. Compared with TOE repair, anchorless rotator cuff repair provides substantial implant-related cost savings, with no significant differences in surgical time for medium and large rotator cuff tears. Case time for TOE repair varied more with extremes in tear size.

Carpal height and postoperative strength after proximal row carpectomy or four-corner arthrodesis: Clinical, anatomical and biomechanical study

Proximal row carpectomy (PRC) and four-corner arthrodesis (4CA) are the two most commonly performed surgical procedures to treat wrist arthritis. Postoperative strength is one of the criteria for choosing between the two techniques. Some authors believe that strength is correlated with residual carpal height. The goal of this study was to determine if postoperative carpal height was predictive of postoperative strength. This study consisted of two parts: a clinical evaluation of grip strength after 4CA or PRC; anatomical and radiological measurements of carpal height before and after 4CA or PRC. Grip strength was better preserved after PRC (87.5%) than after 4CA (76.1%), when expressed relative to the opposite hand (P=0.053). There was a significant decrease in carpal height for the PRC group with a Youm's index of 0.37 versus 0.50 for the 4CA group (P<0.0001). Our clinical results and analysis of the literature indicate that 4CA is not superior to PRC when it comes to grip strength, whereas carpal height is significantly decreased after PRC. The decreased tendon excursion after PRC is balanced by an increase in joint stresses after 4CA.

Shoulder Arthroscopy Does Not Adequately Visualize Pathology of the Long Head of Biceps Tendon.

Background:Pulling the long head of the biceps tendon into the joint at arthroscopy is a common method for evaluation of tendinopathic lesions. However, the rate of missed diagnoses when using this technique is reported to be as high as 30% to 50%.Hypothesis:Tendon excursion achieved using a standard arthroscopic probe does not allow adequate visualization of extra-articular sites of predilection of tendinopathy.Study Design:Descriptive laboratory study.Methods:Seven forequarter amputation cadaveric specimens were evaluated. The biceps tendon was tagged to mark the intra-articular length and the maximum excursions achieved using a probe and a grasper in both beach-chair and lateral positions. Statistical analyses were performed using analysis of variance to compare means.Results:The mean intra-articular and extra-articular lengths of the tendons were 23.9 and 82.3 mm, respectively. The length of tendon that could be visualized by pulling it into the joint with a probe through the anterior midglenoid portal was not significantly different when using either lateral decubitus (mean ± SD, 29.9 ± 3.89 mm; 95% CI, 25.7-34 mm) or beach-chair positions (32.7 ± 4.23 mm; 95% CI, 28.6-36.8 mm). The maximum length of the overall tendon visualized in any specimen using a standard technique was 37 mm. Although there was a trend to greater excursion using a grasper through the same portal, this was not statistically significant. However, using a grasper through the anterosuperior portal gave a significantly greater mean excursion than any other technique (46.7 ± 4.31 mm; 95% CI, 42.6-50.8 mm), but this still failed to allow evaluation of Denard zone C.Conclusion:Pulling the tendon into the joint with a probe via an anterior portal does not allow visualization of distal sites of predilection of pathology. Surgeons should be aware that this technique is inadequate and can result in missed diagnoses.Clinical Relevance:This study demonstrates that glenohumeral arthroscopy does not allow visualization of common areas of pathology of the long head of the biceps tendon.

THE EFFECT OF FREEZING ON BIOMECHANICAL PROPERTIES OF THE CARPAL TUNNEL SUBSYNOVIAL CONNECTIVE TISSUE

Biomechanical evaluation of the subsynovial connective tissue (SSCT) provides insight into the causes of carpal tunnel syndrome. Studies of carpal tunnel mechanics have been performed using fresh-frozen cadaver tissue. Freezing can affect mechanical properties of some tissues, but its effect on SSCT is unknown. A total of 16 rabbit paws were harvested from eight New Zealand rabbits and subjected to mechanical testing consisting of three repeated tendon excursions in sets of three different excursion magnitudes. One paw from each animal was unfrozen. The contralateral paw was frozen and thawed before testing. Force, energy and stiffness of the first cycle of each set were evaluated, as were ratios of the second to first cycle for each parameter. Two-factor ANOVA with repeated measures over both factors was performed. No significant interactions between factors were found. There were no significant differences between fresh and frozen paws for any parameters, though there were significant differences between excursion amplitudes. The damage threshold was not different between fresh and frozen paws. This study demonstrated that freezing rabbit subsynovial connective tissue does not significantly change its mechanical properties. The same may be true for human cadaver tissues. Results of cadaver mechanical testing may not be influenced by this preservation technique.

The Effect of Progressive Extensor Retinaculum Excision on Wrist Biomechanics and Bowstringing

To quantify the effect of the extensor retinaculum in preventing bowstringing and extensor lag. The extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC) tendons to the middle finger were isolated in 6 human cadaveric specimens. Extensor tendon excursion and bowstringing were measured as the extensor retinaculum was serially excised. For the second dorsal compartment, extensor lag averaged 7° when the entire retinaculum over the ECRB was excised. Bowstringing did increase with sequential resections and was greater for distal resections than for proximal resections. When the entire retinaculum over the ECRB was removed, bowstringing averaged 12 mm. For the fourth dorsal compartment, excision of the distal retinaculum resulted in more bowstringing and extensor lag than excision of the proximal retinaculum. When the proximal two-thirds was excised, EDC extensor lag averaged 12° and bowstringing averaged 9 mm; with the distal two-thirds excised, extensor lag averaged 18° and bowstringing averaged 14 mm. Complete retinaculum excision resulted in EDC bowstringing of about 61 mm and extensor lag of 80°. Resection of the entire extensor retinaculum over the second dorsal compartment results in minimal extensor lag and minimal bowstringing. Resection of the entire retinaculum over the fourth dorsal compartment results in massive extensor lag and bowstringing and should be avoided. The distal portion of the retinaculum is most important in preventing extensor lag and bowstringing for the fourth compartment. The findings inform the surgeon's handling of the extensor retinaculum during procedures on the dorsum of the wrist, especially when portions are to be excised, transposed, or repaired.

A Biomechanical Comparison of Suture Button Suspensionplasty versus Ligament Reconstruction with Tendon Interposition for First Carpometacarpal Arthritis: N/A - Not a clinical study

A Biomechanical Comparison of Suture Button Suspensionplasty versus Ligament Reconstruction with Tendon Interposition for First Carpometacarpal Arthritis: N/A - Not a clinical study

Assessment of Tendon Graft Rings for A2 and A4 Hand Pulley Reconstruction: N/A - Not a clinical study

Simultaneous loss of the of the A-2 and A-4 pulleys can cause significant bowstringing of the flexor digitorum profundus. Pulley repair is commonly done with a palmaris tendon loop about the proximal or middle phalanx. The number of loops and the location of the loops can effect the degree of bowstringing. The purpose of this study was to investigate whether repair of the A2 pulley alone in a digit having A2 and A4 pulley incompetence could lead to a good functional outcome and to determine the number of graft rings necessary for proper repair. A motorized apparatus was constructed using potentiometers to measure angular rotation of the digit as a function of tendon excursion. After control (undamaged pulleys) testing, we recorded finger angular rotation as a function of tendon excursion of eleven cadaveric fingers after the following interventions: 1) complete excision of A2 and A4 pulley, 2) repair of distal part of the A2 pulley with one ring of tendon graft, 3) repair of the A2 pulley with two rings of tendon graft, 4) repair of the A2 pulley with two rings of tendon graft and the A4 pulley with one ring. The loss of flexion at full tendon excursion was measured both at the PIP and MCP joint and was calculated as a percentage loss as compared to controls. The loss of the A-2 and A-4 pulleys caused a loss of 32% angular excursion at the MCP joint and 19.6% at the PIP joint. At the PIP joint One ring showed a 14% loss in PIP rotational angle compared to control, 2 rings showed a 17% decrease while the use of three rings, that is, two at A2 and one at A4, had a decrease of 5%. At the MCP joint, with one ring, the decrease in rotational angle was 12% with a second ring 16% whereas with the 3 ring scenario it was 14%. There is significant loss of rotation at both the MCP and PIP associated with loss of the A-2 and A-4 pulley. A double loop at the proximal phalanx fostered no advantage to the single loop. This may involve issues of increased tendon drag. The best reconstruction was the 2 plus 1 pulley reconstruction. The study indicates clinically that in cases of loss of both the A-2 and A-4 pulley, reconstruction of both pulleys should be considered.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Longitudinal In Vivo Ultrasound Observations of the Surgically Repaired Zone II Flexor Digitorum Profundus Tendon

The link between the healing process and functional outcomes in the surgically repaired digital flexor tendon is poorly understood. This clinical note describes those gray-scale and power Doppler (PD) ultrasound parameters that can be used to document longitudinal change in the morphologic and dynamic properties of the surgically repaired zone II flexor digitorum profundus (FDP) tendon. The method is supported by ultrasound data obtained from three participants at five points in time post-surgically (two, four, six, 12 and 18 weeks). Longitudinal documentation of the ultrasound properties of echogenicity, defect size, tendon excursion and power Doppler signal is feasible and has the potential to explore the possible link between changes in the structural status of surgically repaired flexor tendons and associated clinical outcomes.

A closed-form formula for the moment arm matrix of a general musculoskeletal model with considering joint constraint and motion rhythm

This paper introduces a new closed-form formulation for the moment arm matrix corresponding to the musculotendon unit in a general computational model of the musculoskeletal system. The novel approach uses matrix calculus to define a “Generalized Musculotendon Line of Action Vector (GMLAV)” in integration with the virtual work principle, hence leveraging both conventional geometry and tendon excursion methods. In contrast to previous methods, the concepts of motion rhythm and joint constraints have been incorporated without restrictions, where each joint variable is defined as an arbitrary smooth function of the generalized coordinate vector. The validity of our formulation was established by performing the simulations on two well-known musculoskeletal models from literature and comparing the outcomes with those obtained using OpenSim. The results presented in this paper show a high degree of fidelity between our novel simulation model and OpenSim (or SIMM).

Modulating tibiofemoral contact force in the sheep hind limb via treadmill walking: Predictions from an opensim musculoskeletal model.

Sheep are a predominant animal model used to study a variety of orthopedic conditions. Understanding and controlling the in-vivo loading environment in the sheep hind limb is often necessary for investigations relating to bone and joint mechanics. The purpose of this study was to develop a musculoskeletal model of an adult sheep hind limb and investigate the effects of treadmill walking speed on muscle and joint contact forces. We constructed the skeletal geometry of the model from computed topography images. Dual-energy x-ray absorptiometry was utilized to establish the inertial properties of each model segment. Detailed dissection and tendon excursion experiments established the requisite muscle lines of actions. We used OpenSim and experimentally-collected marker trajectories and ground reaction forces to quantify muscle and joint contact forces during treadmill walking at 0.25 m• s(-1) and 0.75 m• s(-1) . Peak compressive and anterior-posterior tibiofemoral contact forces were 20% (0.38 BW, p = 0.008) and 37% (0.17 BW, p = 0.040) larger, respectively, at the moderate gait speed relative to the slower speed. Medial-lateral tibiofemoral contact forces were not significantly different. Adjusting treadmill speed appears to be a viable method to modulate compressive and anterior-posterior tibiofemoral contact forces in the sheep hind limb. The musculoskeletal model is freely-available at www.SimTK.org.

Bond graph model of extensor mechanism of finger based on hook–string mechanism

Biomechanical modeling of a finger is a challenging task especially due to excursion and gliding of tendons along bone geometry, the presence of articular cartilage between mating phalanges, nonlinear viscoelastic properties, load specific change in properties of tendons and complexity of deformable tendinous network (Winslow's rhombus) of the extensor mechanism. In this work, a bond graph model of the extensor mechanism of a finger is developed. Tendons are considered as deformable strings and assumed to pass through hooks fixed at predetermined points on rigid phalanges. This enables them to remain clinging to the phalanx surface while sliding on it, and retain network topology during the movement of phalanges. Word bond graph objects (WBGOs) are developed for dynamics of phalanges, hook–string interaction, normal reaction and frictional forces, and coupling of phalanges in rotation as well as translation, etc. Friction losses and extension of tendons due to applied load are accounted for. Study of motion and tension in tendons, joint variables, location of hooks and characteristics of individual tendons can be conveniently carried out based on the bond graph model. This has been effectively demonstrated through computer simulations.

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.