Flexor Tendon Excursion Research Articles

Digital Thermal Necrosis Resulting in Amputation After Removing a Tungsten Carbide Ring With a High-Speed Metal Burr: A Case Report.

A 41-year-old man removed a tungsten carbide ring from his left index finger by cutting it off with a high-speed metal burr. The patient presented two days later with a pink and perfused left index finger with circumferential dry gangrene along the area of the ring, active flexor and extensor tendon excursion, and decreased sensation distally. Within 24 hours, the wound developed into wet gangrene and diffuse cyanosis requiring amputation. After reviewing previously documented methods to remove tungsten carbide rings, the authors conclude clinicians should be cognizant of the potential complications associated with the use of a high-speed metal burr.

The A1 Pulley as a Fulcrum for Flexor Tendon Excursion: a Histopathological Study

The A1 Pulley as a Fulcrum for Flexor Tendon Excursion: a Histopathological Study

The Impact of Dividing the Flexor Tendon Pulleys on Tendon Excursion and Work of Flexion in a Cadaveric Model

The A2 and A4 pulleys of the flexor tendon system have traditionally been considered critical components of efficient digital flexion. This dogma has recently been challenged. Using fresh human cadaveric hands and a model to measure force and excursion, we sought to clarify the clinical importance of releasing different pulleys. Combinations of A1, A2, and A4 pulleys were released on the index, middle, ring, and little fingers of fresh, cadaveric hands. The excursion was measured as the distance the tendon was pulled by the motor to achieve palm touchdown. The force applied by the motor was constant (25 N); work was derived from the product of force and excursion (distance). The change in excursion and work needed to achieve palm touchdown before and after pulley release was measured. Excursion varies among digits and specimens at baseline; therefore, the percentage change from the intact state was used to compare groups. We compared A2 versus A1, A4 versus A1, A4 versus A2, A1+ A2 versus A2, and A1+ A4 versus A4. Isolated A2 or A4 release had the greatest individual impact on the excursion (4.77% ± 1.52% and 3.88% ± 1.93%, respectively). When A1 was released with A2 (9.90% ± 2.52%), the additional impact on the excursion was significant; however, when A1 was released with A4 (2.63% ± 2.81%), the impact was marginal. No clinically or statistically significant change in the work of flexion was detected. A1 release was clinically significant when added to A2 release but not when added to A4 release. Sacrifice of the A2 and A4 pulleys resulted in a statistically significant, but clinically negligible, difference in flexor tendon excursion. These data suggest that the A1 pulley should be preserved when other proximal pulley components are likely to be compromised. These data also add further support to the concept that the A2 pulley or the A4 pulley can be released as needed for optimal tenorrhaphy. During flexor tendon repair, the length of contiguous pulley release may have more impact on final tendon excursion than which specific pulleys are released.

Effects of wrist extension on median nerve and flexor tendon excursions in patients with carpal tunnel syndrome: a case control study

BackgroundReduced gliding ability of the median nerve in the carpal tunnel has been observed in patients with carpal tunnel syndrome (CTS). The purpose of this study was to evaluate the gliding abilities of the median nerve and flexor tendon in patients with CTS and healthy participants in the neutral and 30° extended positions of the wrist and to compare the gliding between the finger flexion and extension phases.MethodsPatients with CTS and healthy participants were consecutively recruited in a community hospital. All the subjects received the Boston CTS questionnaire, physical examinations, nerve conduction study (NCS), and ultrasonography of the upper extremities. Duplex Doppler ultrasonography was performed to evaluate the gliding abilities of the median nerve and flexor tendon when the subjects continuously moved their index finger in the neutral and 30° extension positions of the wrist.ResultsForty-nine patients with CTS and 48 healthy volunteers were consecutively recruited. Significant differences in the Boston CTS questionnaire, physical examination and NCS results and the cross-sectional area of the median nerve were found between the patients and the healthy controls. The degree of median nerve gliding and the ratio of median nerve excursion to flexor tendon excursion in the CTS group were significantly lower than those in the healthy control group in both the neutral and 30° wrist extension positions. Significantly increased excursion of both the median nerve and flexor tendon from the neutral to the extended positions were found in the CTS group. The ratio of median nerve excursion to flexor tendon excursion was significantly higher in the finger flexion phase than in the extended phase in both groups, and this ratio had mild to moderate correlations with answers on the Boston CTS Questionnaire and with the NCS results.ConclusionsReduced excursion of the median nerve was found in the patients with CTS. The ratio of median nerve excursion to flexor tendon excursion was significantly lower in the patients with CTS than in the healthy volunteers. The median nerve excursion was increased while the wrist joint was extended to 30° in the patients with CTS. Wrist extension may be applied as part of the gliding exercise regimen for patients with CTS to improve median nerve mobilization.

Trigger finger in children with hurler syndrome - distribution pattern and treatment options.

Introduction: Mucopolysaccharidosis is a rare and congenital autosomal recessive lysosomal storage disorder of glycosaminoglycans. An enzyme defect leads to cell, tissue and organ dysfunction. Carpal tunnel syndrome and trigger finger are the results of mucopolysaccharid deposition.Material and methods: We are treating 6 patients with mucopolysaccharide associated trigger fingers in an interdisciplinary setting with the department of pediatric hematology and oncology at Hannover Medical School, where each patient is examined inter alia for symptoms of trigger finger annually.Besides an interview of the parents about abnormalities with regard to hand function, pain and/or neurologic symptoms the children are examined by palpation and by assessment of the active and passive range of finger motion.In the case of finger locking due to an impaired excursion of the flexor tendons in the A2 and A3 pulley region, we performed a trap-door incision technique for A2 pulley widening and a simple release of the A3 pulley.Results: In 6 patients 43 fingers were affected. The average age was 10 years. Pulley thickening was palpated in 19 fingers of to the left hand and 24 fingers of the right hand. In 7 fingers the A1 pulley was affected, in 28 fingers the A2 pulley and in 25 fingers the A3 pulley. The A4 and A5 pulley were not affected in any case. Trigger symptoms were seen in 13 fingers. Five of the 6 children were given an operation indication. In these cases we performed carpal tunnel release, release of Loge de Guyon, and trigger finger release, either in combination or alone. In all cases the procedure led to pain relief and functional improvement.Conclusion: The treatment of trigger fingers in children with mucopolysaccharidosis as a rare disease is challenging with regard to diagnostics and indication.The main treatment goal is pain relief and improvement of hand function.

Flexor tendon grafts for pulley reconstruction – Morphological aspects

BackgroundPulleys are crucial to convert flexor tendon excursion into angular motion at the metacarpophalangeal and interphalangeal joints. Loss of pulley function can lead to significant impairment of hand function and may require surgical reconstruction. This reconstruction can be achieved using different flexor tendons grafts, such as the intrasynovial flexor digitorum superficialis (FDS) or the extrasynovial palmaris longus (PL). However, there is limited knowledge on the micromorphology of human pulleys and the suitability of flexor tendon grafts for their reconstruction remains elusive. MethodsIn the present cadaver study A2 and A4 pulleys were compared with FDS and PL tendons by means of scanning electron microscopy (SEM), histology and immunohistochemistry. Surface morphology, core structure and vascularization of the specimens were analyzed. ResultsSEM imaging of the gliding surfaces revealed morphological differences between tendons and pulleys. Moreover, the core structure of FDS samples was characterized by bundles of individual collagen fibrils whereas PL tendons exhibited a less hierarchical microstructure. In contrast, pulleys consisted of lamellar sheets of densely packed collagen fibrils. Finally, immunohistochemical analyses revealed that the flexor tendons and pulleys contain similar numbers of CD31+ microvessels, indicating a comparable tissue vascularization. ConclusionThis study provides novel SEM and immunohistochemical insights into the micromorphology of human pulleys and flexor tendon grafts. Intrasynovial flexor tendons may be particularly suitable for pulley reconstruction and preserving the paratenon may be crucial for graft revascularization.

Repaired Flexor Tendon Excursion with Half a Fist of True Active Movement Versus Full Fist Place and Hold in the Awake Patient.

Supplemental Digital Content is available in the text.

Atypical Trigger Finger: First Manifestation of Gout

Gout is a form of inflammatory arthritis caused by hyperuricemia characterized by painful, hot and swollen joints. However, tophi involving carpal tunnel with concomitant presence of finger movement dysfunction as the first presentation of gout is rare. This suggests the involvement of flexor tendon inside the carpal tunnel. Here, we report a case of infiltration of tophi at the flexor tendon of the hand presented as the first clinical manifestation of gout causing trigger finger like symptoms. Patient underwent surgery to confirm the diagnosis and improve flexor tendon excursion. Our patient’s finger movement improved dramatically after operation.

Commentary on Sapienza et al. Flexor tendon excursion and load during passive and active simulated motion: a cadaver study

Commentary on Sapienza et al. Flexor tendon excursion and load during passive and active simulated motion: a cadaver study

Use of porcine trotters as models for flexor tendon repair—the pulley system

Porcine trotters have been reported to be useful models for practicing tendon repair surgery. It is difficult to assess the approach of the trainees to pulleys in the in vitro models e.g. pig trotters as the number and the nature of the pulleys is different to that of humans. In this study, we explored the feasibility of fabricating the human pulley system in pig trotter to help provide a better model reflecting human hand. Twenty fresh porcine trotters were dissected. Thick fibro-osseous tunnel covering the flexor tendons was exposed. A template of human pulley system was made and five annular pulleys carved out in the fibro-osseous tunnel. The fabricated pulleys prevented bow stringing, allowing full excursion of the flexor tendons. Thus, a human annular pulley system can be fabricated in a pig trotter model to make it more effective and efficient training model.

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.

Monozygotic twins discordant for pediatric trigger-locked thumbs

Pediatric trigger-locked thumb (PTLT) is a condition frequently encountered by hand surgeons. The term pediatric is more accurate than congenital because most cases do not present at birth. It is possible however that some children are born with the condition but it manifests after birth. The etiology, natural course, ideal treatment, and the age for surgical intervention were all debated in the literature. Children with PTLT typically present under the age of four with the interphalangeal (IP) joint of their thumb locked in flexion. The condition however is seldom preceded by catching, snapping, or triggering of the thumb, which may cause dysfunction and pain. A disparity in the size between the flexor tendon and the surrounding retinacular pulley system, most commonly at the level of the first annular (A1) and partly the oblique pulleys, results in difficulty of flexor pollicis longus tendon gliding hence the triggering/locking phenomenon. This abnormality typically presents at a mean age of two with the IP joint locked in flexion with a palpable nodule in the flexor pollicis longus tendon called Notta’s node. One study observed that in 8.5 % of the cases the condition was diagnosed in the first 2 months following birth, in 53.2 % of the cases between 2 months and 2 years, and in the remainder after 2 years of age [1]. There is some debate about the presentation and whether this condition is truly congenital and present at birth, the pathology is present at birth but manifests later in infancy and childhood, or truly acquired and develops after birth. For these reasons, the term pediatric trigger-locked thumb is more encompassing. The incidence of acquired or pediatric trigger thumb in children under 1 year of age is 33 per 10,000 live births. Bilateral involvement is reported between 25 and 50 % [1, 4]. The treatment of PTLT is releasing the stretched A1 and part of the constricting oblique pulley and restoring flexor tendon excursion and thumb IP joint extension. There has been limited number of literature publications on the etiology of PTLT. The few articles available in the literature on this topic suggest that genetic factors are important in its etiology [5–8, 10, 11]. There are three case reports of “congenital trigger thumb” in twins [3, 4, 8] that support the genetic factors in the etiology of the condition. These reports are based on the fact that the condition occurred in “identical” twins but without a proof of the monozygotic nature of the twins with DNA analysis. We report a case of monozygotic twins discordant for the condition: one with bilateral congenital trigger-locked thumbs and the other with no thumb abnormalities.

The Best Practice for Rehabilitation After Flexor Tendon Repair Remains Elusive

This study, “Ultrasonographic Assessment of Flexor Tendon Mobilization: Effect of Different Protocols on Tendon Excursion,” is an important contribution to our understanding of flexor tendon excursion in the hand. In spite of advances in the surgical repair of lacerated flexor tendons and different modifications of both active and passive motion postoperative treatment programs, “the optimal rehabilitation program after flexor tendon repair is yet to be determined.”1 After surgical repair and healing, the goal of restoring maximum flexor tendon excursion (normally approximately 28 mm for the flexor digitorum superficialis tendon and 33 mm for the flexor digitorum profundus tendon) would allow full motion and normal function2. In this study, Korstanje et al. evaluated three currently used clinical rehabilitation protocols and two experimental models. The following are important strengths of their research. The authors studied the effects of surrounding tissues and the effects of motion or position of adjacent fingers on the excursion of the long finger flexor digitorum profundus tendon. Included in their study were the commonly used modified Kleinert mobilization protocol and the passive four-finger mobilization protocol (hold-and-place method). Because adjacent tissues have been shown to move in the same direction as the flexor tendon3, with greater movement proximal to the metacarpophalangeal joint and smaller movement in zone II4, adhesions attaching the tendon to these surrounding tissues can be assumed to move until they eventually limit tendon excursion. Korstanje et al. did not study cadavers or animals but rather studied normal human subjects with use of a noninvasive technique involving in vivo high-resolution ultrasound to measure the flexor digitorum profundus excursion with five postoperative motion protocols. Ultrasonography is a potential method for the measurement of flexor tendon excursion after tendon repair that has eluded hand surgeons for years. Some surgeons have suggested the use of a radiopaque marker or metallic suture in a repaired tendon to allow for the radiographic measurement of tendon excursion after tendon repair4. The authors concluded that (1) the long finger flexor digitorum profundus tendon excursion was influenced by the position of the adjacent fingers; (2) both the absolute excursion and the relative excursion of the long finger flexor digitorum profundus tendon were decreased if the adjacent fingers remained in extension; (3) there were significant differences between the five protocols; (4) the active four-finger mobilization protocol and the passive four-finger mobilization protocol allowed the best absolute tendon excursion in comparison with the modified Kleinert mobilization protocol (the modified Kleinert protocol achieved only 43% of the absolute tendon excursion that was achieved with the active four-finger protocol and only 56% of that achieved with the passive four-finger protocol) and both experimental models; and (5) currently both experimental protocols probably do not merit use clinically (the extension model because it provided the least excursion of any method and the flexion model because of the difficulty that patients would have keeping the fingers fully flexed into the palm). The limitations of the study were that (1) only eleven healthy subjects completed the study; (2) no actual tendon injuries were studied; (3) the surrounding tissues measured were in zone V, not in another zone, such as the important zone II; and (4) there was a potential inaccuracy of the location on the tendon that was used to measure the tendon’s excursion, namely, the accuracy of the kernel method. This study will serve as a foundation for future clinical studies using ultrasound to measure tendon excursion in other zones, especially zone II, in prospective randomized trials of patients with repaired flexor tendon(s). Investigators can then compare at least the potential best two easily-used rehabilitation protocols (the active and passive four-finger protocols), the modified Kleinert protocol, and others as clinicians seek to prove the ideal postoperative mobilization protocol following flexor tendon repair in the hand.

Carpal Tunnel Syndrome and Finger Movement Dysfunction Caused By Tophaceous Gout: A Case Report

We describe a case of tophaceous gout with a combination of carpal tunnel syndrome and finger movement dysfunction. Carpal tunnel syndrome secondary to gout is uncommon. The concomitant presence of finger movement dysfunction is rare and suggests the involvement of the flexor tendons inside the carpal tunnel. Surgery is recommended to decompress the median nerve, to confirm the diagnosis, and for immediate improvement of flexor tendon excursion. Our patient's finger movement improved dramatically soon after surgery.

Extraarticular Hand Fractures in Adults

This report cites new developments in the treatment of extra-articular hand fractures in adults. Recent reports confirm that small amounts of metacarpal shortening or dorsal angulation cause minimal functional impairment. Unilateral excision of the lateral band and oblique fibers of the extensor apparatus of the metacarpophalangeal joint facilitates proximal phalangeal fracture exposure and may improve functional recovery. Results using open mini screw fixation of oblique extra-articular metacarpal and phalangeal fractures may be comparable to those of percutaneous Kirschner wire fixation. Bicortical self-tapping mini screw fixation of extra-articular oblique metacarpal and phalangeal fractures simplifies screw insertion and provides stability comparable to that of fractures fixed with lag screws. Percutaneous intramedullary wire fixation may afford suitable fixation for unstable extra-articular oblique as well as transverse metacarpal fractures. Locked intramedullary nails may offer similar advantages. Unicortical screw fixation of mini plates securing transverse extra-articular metacarpal fractures affords stability comparable to that of bicortical screw fixation while creating less bone damage. The dissection required for plate fixation and the small surface area of transverse fractures delay and occasionally impair bone healing. Primary bone grafting of diaphyseal defects in clean stable wounds may shorten and simplify treatment and decrease morbidity. As little as 1.7 mm of flexor tendon excursion during the first 4 weeks after reduction or repair may substantially diminish peritendonous adhesions at the fracture site. Synchronous wrist and digital exercises may also reduce peritendonous fracture adhesions. Early motion of adjacent joints in closed simple metacarpal fractures expedites recovery of motion and strength without adversely affecting fracture alignment and leads to earlier return to work. Level V (expert opinion).

Metacarpophalangeal joint mechanics after 3 different silicone arthroplasties

This study was performed to compare metacarpophalangeal (MCP) joint mechanics after arthroplasty with 3 currently available silicone implants and to determine how postarthroplasty mechanics compares with the mechanics of the intact joint. Planar 2-dimensional kinematic analysis was performed using digitized radiographs on 10 isolated fingers harvested from 5 fresh-frozen human cadavers. Radiopaque markers were affixed to the metacarpals and proximal phalanges, sewn to the flexor and extensor tendons, and placed into the stems and hinges of the implants. Each finger was tested intact, and after MCP joint replacement with 3 implants (Swanson [Wright Medical, Memphis, TN], Avanta [Avanta Orthopaedics, San Diego, CA], and NeuFlex [DePuy Orthopaedics, Warsaw, IN]). The fingers were secured to the test fixture and the flexor digitorum profundus flexor and extensor tendons were loaded with physiologic weights. Lateral radiographs were taken at approximately 10 degrees intervals and were digitized on a high-resolution scanner. Instantaneous center of rotation (ICR), tendon excursion, and tendon moment arm were calculated. Statistical analysis was performed using repeated measures one-way analysis of variance and Dunnett post tests. The ICRs of the intact and implanted MCPs did not follow a smooth path. The variability of the ICRs of the intact MCP joints was 2.1 +/- 0.8 mm. The variations in the Avanta and DePuy implants were similar (3.1 +/- 1.0 mm and 3.5 +/- 1.5 mm, respectively), whereas the Swanson implant was higher (4.9 +/- 1.7 mm). Implant pistoning was most pronounced with the Swanson implant, which moved 2.40 +/- 0.97 mm over the full range of motion. The Avanta and DePuy implants pistoned significantly less than the Swanson implant (1.05 +/- 0.45 mm and 0.69 +/- 0.31 mm, respectively). Flexor tendon excursion was greater for the intact joint when compared with all 3 implants while extensor tendon excursion was similar for all. Flexor tendon moment arm was similar for the intact joint and the Avanta and NeuFlex implants whereas the Swanson implant was reduced significantly; extensor tendon moment arms were similar for all. The ICR of the NeuFlex implant most closely matched that of the intact MCP joint. The Swanson implant had greater pistoning and dorsal-volar translation when compared with the intact joint and the Avanta and NeuFlex implants. The block-hinge type design of the Avanta and NeuFlex implants improved tendon moment arm overall when compared with the Swanson, likely imparting greater functional ability for finger motion. Overall the NeuFlex implant most closely matched the ICR, tendon excursion, and moment arm when compared with the intact native MCP joint.

Biomechanical evaluation of flexor tendon function after hamate hook excision

Purpose: Hamate hook fractures are uncommon injuries for which treatment is controversial. Excision of the hamate hook is considered to be the preferred method of treatment but the effects of hamate excision are not clearly delineated. The purpose of this study was to determine what effect, if any, excision of the hamate has on flexor tendon function. Method: The biomechanical effects of hamate hook excision on flexor tendon function were studied in fresh cadaveric forearm specimens with wrists fixed in 3 positions (neutral, 30° extension, 30° extension with 30° ulnar deviation). Flexor tendon force, flexor tendon excursion, and flexor tendon shift were evaluated. Results: Flexor tendon force decreased after hamate hook excision (11% in neutral, 14% in 30° extension, and 15% in 30° extension with 30° ulnar deviation). The flexor profundus tendons had a 7- to 11-mm increase in proximal tendon excursion after hamate hook excision depending on the position of the wrist, and the flexor profundus tendons of the small finger shifted 4 to 5 mm in ulnar direction. Conclusions: The hamate hook provides some biomechanical advantage for flexor tendon function and cadaveric changes in tendon force after its excision suggest that power grip may be decreased after hamate hook excision. (J Hand Surg 2003;28A:138–143. Copyright © 2003 by the American Society for Surgery of the Hand.)

Studies in flexor tendon wound healing: neutralizing antibody to TGF-beta1 increases postoperative range of motion.

The postoperative outcome of hand flexor tendon repair remains limited by tendon adhesions that prevent normal range of motion. Recent studies using in situ hybridization techniques have implicated transforming growth factor beta-1 (TGF-beta1) in both intrinsic and extrinsic mechanisms of repair. TGF-beta1 is a growth factor that plays multiple roles in wound healing and has also been implicated in the pathogenesis of excessive scar formation. The purpose of this study was to examine the effect of neutralizing antibody to TGF-beta1 in a rabbit zone II flexor tendon wound-healing model. Twenty-two adult New Zealand White rabbits underwent complete transection of the middle digit flexor digitorum profundus tendon in zone II. The tendons were immediately repaired and received intraoperative infiltration of one of the following substances: (1) control phosphate-buffered saline; (2) 50 microg neutralizing antibody to TGF-beta1; (3) 50 microg each of neutralizing antibody to TGF-beta1 and to TGF-beta2. Eight rabbits that had not been operated on underwent analysis for determination of normal flexion range of motion at their proximal and distal interphalangeal joints, using a 1.2-N axial load applied to the flexor digitorum profundus tendon. All rabbits that had been operated on were placed in casts for 8 weeks to allow maximal tendon adhesion and were then killed to determine their flexion range of motion. Statistical analysis was performed using the Student's unpaired t test. When a 1.2-N load was used on rabbit forepaws that had not been operated on, normal combined flexion range of motion at the proximal and distal interphalangeal joints was 93+/-6 degrees. Previous immobilization in casts did not reduce the range of motion in these forepaws (93+/-4 degrees). In the experimental groups, complete transection and repair of the flexor digitorum profundus tendon with infiltration of control phosphate-buffered saline solution resulted in significantly decreased range of motion between the proximal and distal phalanges [15+/-6 degrees (n = 8)]. However, in the tendon repairs infiltrated with neutralizing antibody to TGF-beta1, flexion range of motion increased to 32+/-9 degrees (n = 7; p = 0.002). Interestingly, a combination of neutralizing antibody to TGF-beta1 and that to TGF-beta2 did not improve postoperative range of motion [18+/-4 degrees (n = 7; p = 0.234)]. These data demonstrate that (1) the rabbit flexor tendon repair model is useful for quantifying tendon scar formation on the basis of degrees of flexion between proximal and distal phalanges; (2) intraoperative infiltration of neutralizing antibody to TGF-beta1 improves flexor tendon excursion; and (3) simultaneous infiltration of neutralizing antibody to TGF-beta2 nullifies this effect. Because TGF-beta1 is thought to contribute to the pathogenesis of excessive scar formation, the findings presented here suggest that intraoperative biochemical modulation of TGF-beta1 levels limits flexor tendon adhesion formation.

The effect of gap formation at the repair site on the strength and excursion of intrasynovial flexor tendons. An experimental study on the early stages of tendon-healing in dogs.

Elongation (gap formation) at the repair site has been associated with the formation of adhesions and a poor functional outcome after repair of flexor tendons. Our objectives were to evaluate the prevalence of gap formation in a clinically relevant canine model and to assess the effect of gap size on the range of motion of the digits and the mechanical properties of the tendons. We performed operative repairs after sharp transection of sixty-four flexor tendons in thirty-two adult dogs. Rehabilitation with passive motion was performed daily until the dogs were killed at ten, twenty-one, or forty-two days postoperatively. Eight tendons ruptured in vivo. In the fifty-six intact specimens, the change in the angles of the proximal and distal interphalangeal joints and the linear excursion of the flexor tendon were measured as a 1.5-newton force was applied to the tendon. The gap at the repair site was then measured, and the isolated tendons were tested to failure in tension. Twenty-nine tendons had a gap of less than one millimeter, twelve had a gap of one to three millimeters, and fifteen had a gap of more than three millimeters. Neither the time after the repair nor the size of the gap was found to have a significant effect on motion parameters (p > 0.05); however, the ultimate force, repair-site rigidity, and repair-site strain at twenty newtons were significantly affected by these parameters (p < 0.05). Testing of the tendons with a gap of three millimeters or less revealed that, compared with the ten-day specimens, the forty-two-day specimens failed at a significantly (90 percent) higher force (p < 0.01) and had a significantly (320 percent) increased rigidity (p < 0.01) and a significantly (60 percent) decreased strain at twenty newtons (p < 0.05). In contrast, the tensile properties of the tendons that had a gap of more than three millimeters did not change significantly with time. Our data indicate that, in a dog model involving sharp transection followed by repair, a gap at the repair site of more than three millimeters does not increase the prevalence of adhesions or impair the range of motion but does prevent the accrual of strength and stiffness that normally occurs with time.

Wrist and digital joint motion produce unique flexor tendon force and excursion in the canine forelimb

The force and excursion within the canine digital flexor tendons were measured during passive joint manipulations that simulate those used during rehabilitation after flexor tendon repair and during active muscle contraction, simulating the active rehabilitation protocol. Tendon force was measured using a small buckle placed upon the tendon while excursion was measured using a suture marker and video analysis method. Passive finger motion imposed with the wrist flexed resulted in dramatically lower tendon force (∼5 N) compared to passive motion imposed with the wrist extended (∼17 N). Lower excursions were seen at the level of the proximal interphalangeal joint with the wrist flexed (∼1.5 mm) while high excursion was observed when the wrist was extended or when synergistic finger and wrist motion were imposed (∼3.5 mm). Bivariate discriminant analysis of both force and excursion data revealed a natural clustering of the data into three general mechanical paradigms. With the wrist extended and with either one finger or four fingers manipulated, tendons experienced high loads of ∼1500 g and high excursions of ∼3.5 mm. In contrast, the same manipulations performed with the wrist flexed resulted in low tendon forces (4–8 N) and low tendon excursions of ∼1.5 mm. Synergistic wrist and finger manipulation provided the third paradigm where tendon force was relatively low (∼4 N) but excursion was as high as those seen in the groups which were manipulated with the wrist extended. Active muscle contraction produced a modest tendon excursion (∼1 mm) and high or low tendon force with the wrist extended or flexed, respectively. These data provide the basis for experimentally testable hypotheses with regard to the factors that most significantly affect functional recovery after digital flexor tendon injury and define the normal mechanical operating characteristics of these tendons.