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

Calculation of flexor pollicis longus moment arm for wrist motion in a cadaver model validates the tenodesis effect for therapy

INTRODUCTION

Synergies of fingers and wrist motion have been incorporated into therapies for finger flexor tendon injuries to improve repair outcomes. Similar synergistic therapy strategies have not been well documented for the thumb.

PURPOSE OF THE STUDY

The purpose of this study was to investigate the extent to which wrist motion enables a synergistic effect at the thumb in a cadaveric model by measuring flexor pollicis longus excursion and calculating the moment arm of this tendon at the wrist joint.

STUDY DESIGN

This is a basic science research.

METHODS

Eight fresh-frozen cadaveric arms were obtained from our anatomical bequest program. The proximal arm was fixed in neutral pronation/supination position, and motion of the wrist was guided through either flexion/extension or radial/ulnar deviation. Fingers were fixed in extension, thumb interphalangeal and metacarpophalangeal joints were fixed in neutral extension, and the carpometacarpal joint was fixed at 30° palmar abduction. The flexor pollicis longus tendon was exposed proximal to the wrist crease and connected to a rotary potentiometer to measure tendon excursion. Optical markers were attached to the hand to capture kinematics. Wrists were moved from a neutral position over the range of flexion and extension and then from the neutral position through the range of radial to ulnar deviation. Moment arms were calculated.

RESULTS

Moment arm calculation indicated that the flexor pollicis longus acts as a wrist flexor over the entire motion range and as a weak radial deviator at ulnarly-deviated positions.

CONCLUSIONS

This study provides a mechanistic rationale for passive interphalangeal joint motion in varying wrist positions when treating thumb flexor tendon injuries, with benefits seen primarily for wrist extension.

Ultrasonographic assessment in vivo of the excursion and tension of flexor digitorum profundus tendon on different rehabilitation protocols after tendon repair

STUDY DESIGN

Interpretive description study.

PURPOSE

In management of patients with flexion tendon injuries, passive, control active and active motion protocols were proposed after repair to minimize tendon adhesion. The purpose of this study was to compare the excursion distance and the tension of Flexor Digitorum Profundus (FDP) during simulated active and passive motion using ultrasonography techniques using normal subjects.

METHODS

Ultrasonographic assessment of FDP tendon of the middle finger was performed at the wrist level on 20 healthy college students using 3 types of treatment protocols: modified Kleinert protocol, modified Duran protocol, and active finger flexion protocol. The excursion distance was measured following the musculotendinous junction of FDP using the B mode ultrasound system. The elasticity of FDP tendon was measured using the shear wave elastography technique. The excursion distance and the elasticity value were compared among 3 protocols using one-way ANOVA analysis.

RESULTS

Twelve male and 8 female students with mean age of 22.6 ± 1.8 years were invited to join the study. The excursion distance of FDP was 21.82 ± 3.77 mm using the active finger flexion protocol, 8.59 ± 2.59 mm using the modified Duran protocol, and 12.26 ± 2.71 mm using the modified Kleinert protocol. The elasticity was significantly higher in extension position when compared to passive flexion positions, but found lower than active flexion position.

DISCUSSION

The active finger protocol was found to require strongest tension of the tendon and with longest excursion. There was similar tension generated using both passive motion protocols. The modified Duran protocol appeared to create less excursion upon movements than the modified Kleinert approach using the objective ultrasonic evaluation. It is suggested that if the surgical repair was strong and without any complications, the active flexion protocol might work best to regain tension excursion. However, if there are complex problems involved, then the Kleinert approach or Duran approach would be chosen.

Pathomechanics and Management of Secondary Complications Associated with Tendon Adhesions Following Flexor Tendon Repair in Zone II

Despite the number of rehabilitation strategies and guidelines developed to maximize the gliding amplitude of repaired tendons, secondary complications, such as decreased range of motion and stiffness associated with tendon adhesions, commonly arise. If left untreated, these early complications may lead to secondary pathomechanical changes resulting in fixed deformities and decreased function. Therefore, an appropriate treatment regimen must not only include strategies to maintain the integrity of the repaired tendon, but must also avoid secondary complications due to reduced gliding amplitude. This review presents a biomechanical analysis of the dynamics of tendon gliding following repair in zone II and rehabilitation strategies to minimize secondary complications related with tendon adhesions.

Flexor tendon excursion and load during passive and active simulated motion: a cadaver study

The aim of this study was to quantify the amount of tendon excursion and load experienced during simulated active and passive rehabilitation exercises. Six cadaver specimens were utilized to examine tendon excursion and load. Lateral fluoroscopic images were used to measure the excursions of metal markers placed in the flexor digitorum superficialis and profundus tendons of the index, middle, and ring fingers. Measurements were performed during ten different passive and active simulated motions. Mean tendon forces were higher in all active versus passive movements. Blocking movements placed the highest loads on the flexor tendons. Active motion resulted in higher tendon excursion than did passive motion. Simulated hook position resulted in the highest total tendon excursion and the highest inter-tendinous excursion. This knowledge may help optimize the management of the post-operative exercise therapy regimen.

Surgical reconstruction and mobilization therapy for a retracted extensor hallucis longus laceration and tendon defect repaired by split extensor hallucis longus tendon lengthening and dermal scaffold augmentation

A reconstructive technique and physical therapy protocol is presented for the treatment of extensor hallucis longus (EHL) lacerations with critical size defects caused by tendon retraction. The primary goal of treatment was to restore EHL structure and function without the use of a bridging allograft or tendon transfer. The technique is performed by split lengthening the distal segment of the lacerated EHL and rotating the lengthened segment proximally 180° to bridge the tendon defect. The lengthened tendon is then sutured to the proximal segment of the EHL. The EHL is then tubularized with an acellular dermal scaffold at the region of tendon rotation to improve tendon strength, minimize the probability of tendon overlengthening or re-rupture, and improve the tendon gliding motion, which can be compromised by the tendon irregularity caused by rotation of the tendon. Postoperative range of motion therapy should be initiated at 3 weeks postoperatively. A case report of this technique and postoperative mobilization protocol is presented. The American Orthopaedic Foot and Ankle Society midfoot score at 3 and 6 months postoperatively was 90 of 100. The patient regained active dorsiflexion motion of the hallux without functional limitations, deformity, or contracture of the hallux. The advantages of this technique include that a large cadaveric allograft is not needed to bridge a critical size tendon defect and tendon lengthening provides a biologically active tendon graft without the secondary comorbidities and dysfunction commonly associated with tendon transfer procedures.

Ultrasonographic assessment of flexor tendon mobilization: effect of different protocols on tendon excursion

BACKGROUND

Different mobilization protocols have been proposed for rehabilitation after hand flexor tendon repair to provide tendon excursion sufficient to prevent adhesions. Several cadaver studies have shown that the position of the neighboring fingers influences tendon excursions of the injured finger. We hypothesized that the positions of adjacent fingers influence the long finger flexor digitorum profundus tendon excursion, measured both absolutely and relative to the surrounding tissue of the tendon.

METHODS

Long finger flexor digitorum profundus tendon excursions and surrounding tissue movement were measured in zone V in eleven healthy subjects during three different rehabilitation protocols and two experimental models: (1) an active four-finger mobilization protocol, (2) a passive four-finger mobilization protocol, (3) a modified Kleinert mobilization protocol, (4) an experimental modified Kleinert flexion mobilization model, and (5) an experimental modified Kleinert extension mobilization model. Tendon excursions were measured with use of a frame-to-frame analysis of high-resolution ultrasound images.

RESULTS

The median absolute long finger flexor digitorum profundus tendon excursions were 23.4, 17.8, 10.0, 13.9, and 7.6 mm for the active four-finger mobilization protocol, the passive four-finger mobilization protocol, the modified Kleinert mobilization protocol, the experimental modified Kleinert flexion mobilization model, and the experimental modified Kleinert extension mobilization model, respectively, and these differences were all significant (p ≤ 0.041). The corresponding relative flexor digitorum profundus tendon excursions were 11.2, 8.5, 7.2, 10.4, and 5.6 mm. Active four-finger mobilization protocol excursions were significantly (p = 0.013) greater than passive four-finger mobilization protocol excursions but were not significantly greater than experimental modified Kleinert flexion mobilization model excursions (p =0.213).

CONCLUSIONS

The present study demonstrated large and significant differences among the different rehabilitation protocols and experimental models in terms of absolute and relative tendon displacement. More importantly, the present study clearly demonstrated the influence of the position of the adjacent fingers on the flexor tendon displacement of the finger that is mobilized.

Post-traumatic combined flexion of the thumb, index and middle finger after intrinsic muscles reconstruction of the hand: a case report

We report a case in which simultaneous flexion of the thumb, index and middle finger occurred 6 months after the surgical reconstruction of the adductor (AM) and first dorsal interosseous (IO) muscles. An anomalous connection in the form of tendon slip associated to fibrous adhesions between the flexor pollicis longus (FPL) tendon, flexor digitorum profundus indicis (FDPI) and middle finger (FDPM) tendons were found. Either ultrasound (US) examination or magnetic resonance imaging (MRI) were unable to detect the site of adhesion. Excision of the slip and radical tenosynoviectomy led to early functional recovery.

Ultrasonographic assessment of long finger tendon excursion in zone v during passive and active tendon gliding exercises

PURPOSE

Cadaver and in vivo studies report variable results for tendon excursion during active and passive hand movements. The purpose of this study was to measure long finger flexor digitorum profundus (FDP) tendon excursion during active and passive movement using high-resolution ultrasound images.

METHODS

The FDP tendon excursion was measured at the wrist level in 10 healthy subjects during full tip-to-palm active and passive flexion of the fingers. Passive movement was performed 2 ways: (1) straight to full fist: passive flexion starting at the metacarpophalangeal joint, followed by proximal interphalangeal and distal interphalangeal joint flexion; and (2) hook to full fist: passive flexion starting at the distal interphalangeal joint, followed by proximal interphalangeal and metacarpophalangeal joint flexion. Tendon excursion was measured using an in-house-developed, frame-to-frame analysis of high-resolution ultrasound images.

RESULTS

Median FDP excursion was 24.3 mm, 14.0 mm, and 13.6 mm for active fist, straight to full fist, and hook to full fist movements, respectively. Tendon excursions during active movements was significantly larger than excursions during passive movements (p = .005). The adjusted median tendon excursion was 12.7 mm/100 degrees , 7.5 mm/100 degrees , and 7.4 mm/100 degrees for active fist, straight to full fist, and hook to full fist movements, respectively. Adjusted tendon excursions during active movement were significantly larger than those achieved during passive straight to full fist movement). Adjusted tendon excursions during straight to full fist movements were significantly larger than those achieved during passive hook to full fist movement.

CONCLUSIONS

Active motion produced 74% and 79% increases in excursions compared to both passive motions in healthy controls. The study results can serve as a reference for evaluating excursions in patients with tendon pathology, including those who have had tendon repair and reconstruction.

A feasibility study for measuring accurate tendon displacements using an audio-based Fourier analysis of pulsed-wave Doppler ultrasound signals

The accuracy of Pulsed-Wave Doppler Ultrasound displacement measurements of a slow moving "tendon-like" string was investigated in this study. This was accomplished by estimating string displacements using an audio-based Fourier analysis of a Pulsed-Wave Doppler signal from a commercial ultrasound scanner. Our feasibility study showed that the proposed technique is much more accurate at estimating the actual string displacement in comparison to the scanner's onboard software. Furthermore, this study also shows that a real-time Doppler data acquisition from an ultrasound scanner is possible for the ultimate purpose of real-time biological tendon displacement monitoring.

Biomechanical evaluation of flexor tendon repair techniques

Immediate active mobilization of repaired tendons is thought to be the most effective way to restore function of injured flexor tendons. Sixty human flexor digitorum profundus tendons were used to evaluate techniques for active tendon motion. The tendons were divided equally into six groups, and each group was assigned to one of the following techniques: Kessler core suture plus running peripheral suture, Kessler plus cross-stitch suture, Kessler plus Halsted suture, Tang core suture plus running peripheral suture, Tang plus cross-stitch suture, or Tang plus Halsted suture. Immediately after tendon repair, an Instron tensile testing machine was used to measure the 2-mm gap formation force, ultimate strength, elastic modulus, and energy to failure of the tendons repaired by these techniques. Ultimate strength, elastic modulus, and energy to failure were measured in load displacement curve. Results showed that the ultimate strength of the Tang plus Halsted or cross-stitch was, respectively, 116.8 +/- 9.6 N and 94.6 +/- 7.8 N; and 2-mm gap formation force was, respectively, 86.6 +/- 4.9 N and 71.9 +/- 5.1 N. The Tang plus Halsted or cross-stitch methods had a statistically significant increase in ultimate strength and 2-mm gap formation force as compared with the Kessler core suture or Tang plus running peripheral suture method. Elastic modulus and energy to failure of the Tang plus Halsted or cross-stitch suture were statistically higher than those of other techniques. The Tang plus cross-stitch or Tang plus Halsted sutures had the highest strength among the tested methods and are appropriate techniques for tendon repair in which the goal is immediate active tendon motion.