Tenectomy of the superficial digital flexor tendon as a treatment of suspected septic tendinitis and tenosynovitis of the digital flexor tendon sheath followed by rehabilitation with an orthotic device

A 15-year-old Sports horse gelding was referred for nonweightbearing lameness of the left hindlimb. Septic cellulitis was diagnosed and managed medically. After 14 days, septic tenosynovitis of the digital flexor tendon sheath (DFTS), with septic tendinitis of the superficial (SDFT) and deep (DDFT) digital flexor tendons, became evident. Surgical resection of the intrathecal portion of the septic SDFT was performed. Post-operatively, a half-limb cast was placed on the operated limb for 10 weeks followed by an articulated orthotic support boot during a rehabilitation period of 6 weeks. The horse recovered and regained long-term pasture soundness. Ultrasonography demonstrated the presence of bridging connective tissue in the location of the resected SDFT.     

Healing of Transected Equine Superficial Digital Flexor Tendons With and Without Tenorrhaphy

Healing of transected superficial digital flexor tendons was evaluated mechanically and histologically in eight horses. Tendons sutured with polyglyconate had higher loads at failure than nonsutured tendons at weeks 5 and 9. The tendon stress at failure (force per unit area) was higher in the sutured tendons at week 5 but not at week 9, reflecting the increased size of the scar at week 9. Histologically, scars after tenorrhaphy were consistently more mature than nonsutured tenotomy scars. The mean maturity score for sutured tendons was higher than for nonsutured tendons at weeks 5 and 9. Overall, these data support tenorrhaphy with absorbable suture.     

Desmotomy of the accessory ligament of the superficial digital flexor tendon in the horse with use of a tenoscopic approach to the carpal sheath

Objective— To describe a tenoscopic approach to the carpal sheath for desmotomy of the accessory ligament of the superficial digital flexor tendon. Study Design— The surgical procedure was developed with use of normal forelimbs from equine cadavers and experimental horses. Animals or Sample Population— Twelve equine cadaveric forelimbs, 4 forelimbs from 2 horses anesthetized for terminal surgical laboratories, and 10 forelimbs from five experimental horses were used. Methods— The limbs were positioned lateral side up with the carpus slightly flexed. After distention of the carpal sheath, a portal was made approximately 2 cm proximal to the distal radial physis for arthroscope insertion. An instrument portal was made approximately 0.2 cm proximal to the distal radial physis. After flexion of the limb to 90°, the accessory ligament of the superficial digital flexor tendon was palpated and desmotomy was performed. Cadaveric limbs were dissected to confirm complete desmotomy. Experimental horses were monitored for short- (perioperative) and long- (4 weeks) term postoperative complications. Results— A tenoscopic approach to the carpal sheath provided adequate surgical access to the accessory ligament of the superficial digital flexor tendon for desmotomy. Most of the accessory ligament of the superficial digital flexor tendon could be easily seen within the sheath, except for the proximal 2 cm that could be readily palpated and subsequently transected. Important technical considerations were location of the arthroscope portal, adequate sheath distention, limb flexion to 90°, and desmotomy location. It was beneficial, but apparently not essential, to avoid the proximal perforating vessel. Postoperatively, some horses had swelling but were not lame and had normal range of motion of the carpus. Conclusions— Desmotomy of the accessory ligament of the superficial digital flexor tendon could be performed by using a lateral tenoscopic approach to the carpal sheath. Clinical Relevance— Desmotomy of the accessory ligament of the superficial digital flexor tendon by using a tenoscopic approach to the carpal sheath is an alternative technique to the medial incisional approach.     

Dynamic flexion/extension and non‐weight bearing ultrasonography is helpful for identifying manica flexoria tears in horses

Lesions of the manica flexoria are a tenoscopic finding in horses with digital flexor tendon sheath tenosynovitis. This retrospective case series study describes the ultrasonographic findings in seven horses admitted for digital flexor tendon sheath swelling associated with lameness and tenoscopic confirmation of a manica flexoria tear. Six horses had a partial manica flexoria tear, one a complete rupture. The ultrasonographic examination included a static examination on the weight and non‐weight bearing limb and a dynamic limb assessment during flexion and extension. The main ultrasonographic finding at the static weight bearing examination in horses with a partial tear was an asymmetrical appearance of the manica flexoria at the level of the junction with the lateral border of the superficial digital flexor tendon, or an incomplete visualization of the manica flexoria in case of complete rupture. The split edges of the completed ruptured manica flexoria were seen floating in the synovial fluid at the examination in flexion. In six of seven cases, the superficial digital flexor tendon slid abnormally relative to the deep digital flexor tendon, during flexion/extension movements, with medial displacement of the superficial digital flexor tendon, appearance of an anechoic gap between the flexor tendons or reduced superficial digital flexor tendon sliding. Because ultrasonographic diagnosis of the manica flexoria tear is considered challenging, detection of these ultrasonographic features is helpful to increase the likelihood of identifying manica flexoria tears prior to tenoscopy. Authors recommend static ultrasonographic examination of the manica flexoria using a flexed limb position and dynamic ultrasonographic examination using flexion and extension positioning for horses with suspected digital sheath injury.     

EVALUATION OF THE EQUINE DIGITAL FLEXOR TENDON SHEATH USING DIAGNOSTIC ULTRASOUND AND CONTRAST RADIOGRAPHY

This study was designed to evaluate the normal anatomy of the digital flexor tendon sheath using contrast radiography and diagnostic ultrasound. Iodinated contrast medium was injected into eight cadaver limbs and the limbs immediately frozen. Lateromedial and dorsopalmar/plantar radiographs were made. These limps were then cut transversely and proximal to distal radiographs of each slab were made. This cross sectional contrast methodology allowed the visualization of the relative size and shape of the superficial and deep digital flexor tendons as well as the potential space taken by effusions of the digital flexor tendon sheath.
The second part of the study used twelve live animals with normal digital flexor tendon sheaths. Ultrasonographic measurement of the structures of the digital flexor tendon sheath at each level were compiled. This documented the ability of diagnostic ultrasound to image: 1) the superficial and deep digital flexor tendons, 2) the proximal and distal ring of the manica flexoria , 3) the straight and oblique sesamoidean ligaments, and 4) the mesotendinous attachments to the superficial and deep flexor tendons. Iodinated contrast medium was then injected into the digital flexor tendon sheath and the ultrasonography repeated. These images were compared with those obtained from contrast radiography and prosections of twenty normal limbs. The iodinated contrast medium enhanced sonographic imaging of the structures of the digital tendon sheath, particularly the abaxial borders of the superficial digital flexor tendon branches and the mesotendinous attachments to the superficial and deep digital flexor tendons.     

Ex vivo strength comparison of bioabsorbable tendon plates and bioabsorbable suture in a 3-loop pulley pattern for repair of transected flexor tendons from horse cadavers

OBJECTIVE: To test the failure strength and energy of 2 bioabsorbable implants applied to transected deep digital flexor tendons (DDFT) from adult horses. STUDY DESIGN: Ex vivo biomechanical experiment. SAMPLE POPULATION: Twelve pairs of deep digital flexor tendons harvested from the forelimbs of fresh equine cadavers. METHODS: Poly-L-lactic acid tendon plates were custom manufactured for application to the cylindrical surface of an adult equine deep digital flexor tendon. Twelve pairs of DDFTs were transected 2 cm distal to the insertion of the distal check ligament of the deep digital flexor tendon. One tendon of each pair was randomly selected for repair with a biodegradable plate or a 3-loop pulley method. Size 2 polydioxanone suture was used in both repairs. Repairs were tested in tension to failure, with peak force (PF) and total energy (TE) at repair failure recorded in Newtons (N) and Joules (J), respectively. A paired t-test was used for statistical evaluation with a significant level set at P< or = .05. RESULTS: Mean+/-SD PF for failure of plated tendons (1507.08+/-184.34 N) was significantly greater than for sutured tendons (460.86+/-60.93 N). TE was also significantly greater for failure of plated tendons versus sutured tendons. CONCLUSIONS: Plate fixation of transected cadaver DDFTs appear to have superior immediate failure strength than 3-loop pulley repairs. CLINICAL RELEVANCE: Whereas in vivo testing is required, a bioabsorbable tendon plate may provide initial increased strength to support tendon healing and decrease external coaptation requirements.     

Identification of surgically-induced longitudinal lesions of the equine deep digital flexor tendon in the digital flexor tendon sheath using contrast-enhanced ultrasonography: an ex-vivo pilot study

Background

Longitudinal tears in the lateral aspect of the deep digital flexor tendon are the most common causes of pain localised to the equine digital flexor tendon sheath. However conventional ultrasonographic techniques provide limited information about acute lesions. Ultrasonographic contrast agents are newly developed materials that have contributed to advancement in human diagnostic imaging. They are currently approved for intravenous use in human and animal models. In this study we described intrathecal use in the horse. This study was undertaken to evaluate the reliability of standard and angle contrast-enhanced ultrasonography to detect and characterize surgically-induced longitudinal lesions in the deep digital flexor tendons.In this pilot study surgically-induced lesions were created in the lateral aspect of the deep digital flexor tendon within the digital flexor tendon sheath in 10 isolated equine limbs to generate a replicable model for naturally occurring lesions. Another 10 specimens were sham operated. All the limbs were examined ultrasonographically before and shortly after the intrasynovial injection of an ultrasound contrast agent containing stabilised microbubbles. The images were blindly evaluated to detect the ability to identify surgically-created lesions. The deep digital flexor tendons were dissected and a series of slices were obtained. The depth of longitudinal defects identified with contrast-enhanced ultrasound scans was compared to the real extent of the lesions measured in the corresponding gross tendon sections.

Results

Contrast-enhanced ultrasonography with both angle and standard approach provided a significant higher proportion of correct diagnoses compared to standard and angle contrast ultrasonography (p < 0.01). Contrast-enhanced ultrasonography reliably estimated the depth of surgically-induced longitudinal lesions in the deep digital flexor tendons.

Conclusion

Contrast-enhanced ultrasound of the digital flexor tendon sheath could be an effective tool to detect intrasynovial longitudinal tears of the deep digital flexor tendon, although an in vivo study is required to confirm these results for naturally occurring lesions.     

A Histological Evaluation of Rabbit Tendons Sutured Using the Bunnell Pattern

Development of ischemia in healing tendons was assessed in 18 rabbits. One superficial digital flexor tendon in each rabbit was incised and anastomosed using a Bunnell pattern. The repair site was enclosed in a porous, woven Dacron tube before skin closure. The limb was immobilized with a cast. Rabbits were euthanized 1, 4, and 8 weeks after surgery, and tendons were harvested and examined microscopically. Regions of the tendon included in the suture pattern were ischemic and acellular at 1 week, while adjacent areas still containing patent vessels remained viable. Within 4 weeks, a well vascularized neotendon with collagen bundles organized parallel to the long axis of the tendon developed along the periphery and between the opposed tendon ends. After 8 weeks, the ischemic regions of the tendon had not revascularized or become integrated with the neotendon. Adjacent collagen bundles not originally included in the Bunnell pattern were integrated with neotendon collagen fibers.     

Effects of sodium hyaluronate on tendon healing and adhesion formation in horses

Sodium hyaluronate reduces adhesions after tendon repair in rodents and dogs, and has been used in limited clinical trials in people. To evaluate its effect on tendon healing and adhesion formation in horses and to compare these effects with those of a compound of similar visco-elastic properties, a study was performed in horses, using a model of collagenase injection in the flexor tendons within the digital sheath. Eight clinically normal horses were randomly allotted to 2 groups. Adhesion formation between the deep digital flexor tendon and the tendon sheath at the pastern region was induced in the forelimbs of all horses. Using tenoscopic control, a 20-gauge needle was inserted into the deep digital flexor tendon of horses under general anesthesia and 0.2 ml of collagenase (2.5 mg/ml) was injected. The procedure was repeated proximally at 2 other sites, spaced 1.5 cm apart. A biopsy forceps was introduced, and a 5-mm tendon defect was created at each injection site. Group-A horses had 120 mg of sodium hyaluronate (NaHA) gel injected into the tendon sheath of one limb. Group-B horses had methylcellulose gel injected at the same sites. The contralateral limbs of horses in both groups served as surgical, but noninjected, controls. Horses were euthanatized after 8 weeks of stall rest. Ultrasonographic evaluation revealed improved tendon healing after NaHa injection, but no difference in peritendinous adhesion formation. Tendon sheath fluid volume and hyaluronic acid (HA) content were greater in NaHA-treated limbs. Gross pathologic examination revealed considerably fewer and smaller adhesions when limbs were treated with NaHA. However, significant difference in pull-out strengths was not evident between NaHA-treated and control limbs. Histologically, the deep digital flexor tendon from the NaHA-treated limbs had reduced inflammatory cell infiltration, improved tendon structure, and less intratendinous hemorrhage. Treatment with methylcullulose had no significant effect on tendon healing, adhesion size, quantity, or strength or on the volume and composition of the tendon sheath fluid. Sodium hyaluronate, administered intrathecally, appears to have a pharmaceutically beneficial action in this collagenase-induced tendinitis and adhesion model in horses.     

Tenoscopic Anatomy of the Equine Carpal Flexor Synovial Sheath

Objective —To describe the tenoscopic anatomy of the carpal sheath of the flexor tendons (carpal sheath) viewed from a lateral approach.
Study Design —Tenoscopic observation of structures within the carpal sheath subsequently confirmed by dissection.
Animals or Sample Population—12 equine cadaveric forelimbs.
Methods —The limbs were positioned lateral side up with the carpus slightly flexed. After distention of the carpal sheath, a portal for the arthroscope was made approximately 3 cm proximal to the distal radial physis and 2.5 cm caudal to the radius between the tendons of the ulnaris lateralis and lateral digital extensor muscles.
Results —A lateral tenoscopic approach was adequate to identify all structures within the carpal sheath. From proximal to distal, structures identified using this approach were the radial head of the deep digital flexor muscle, accessory ligament of the tendon of the superficial digital flexor muscle, distal radial physis, tendons of the superficial and deep digital flexor muscles, accessory carpal bone, antebrachiocarpal and middle carpal joints, and vincula of the tendon of the deep digital flexor muscle.
Conclusions —A lateral tenoscopic approach offered an easy, repeatable entry into the carpal sheath and allowed good observation of all structures within the sheath except for the medial borders of the tendons of the deep and superficial digital flexor muscles.
Clinical Relevance —Applications of a lateral tenoscopic approach to the carpal sheath include diagnostic procedures, lavage and synovial resection for septic tenosynovitis, desmotomy of the accessory ligament of the tendon of the superficial digital flexor muscle for flexural deformity or tendinitis, and removal of osteochondromas from the distal radial metaphysis.     

Healing of surgically created defects in the equine superficial digital flexor tendon: effects of pulsing electromagnetic field therapy on collagen-type transformation and tissue morphologic reorganization

The effect of pulsing electromagnetic field (PEMF) therapy on the healing of surgically created defects in equine superficial digital flexor tendons was evaluated. Defects were created in both front superficial digital flexor tendons of 20 horses. The defect in 1 limb was exposed to a PEMF for 2 hours daily. The other limb served as a control. Histologic and immunofluorescent evaluations were done in horse killed at postsurgical weeks 2, 4, 8, 12, and 24. Therapy with the PEMF significantly (P less than 0.05) delayed the maturation of the tissue formed within the defect at postsurgical weeks 8 and 12, as determined by histologic examination. The collagen-type transformation was also delayed by the PEMF therapy, but to a degree that was not significant.     

A Comparison of Repair Methods for Gap Healing in Equine Flexor Tendon

In nine horses (18 forelimbs), a 3 cm section of superficial digital flexor tendon was removed and the tendons were repaired with immobilization for 6 weeks and (1) no suture (n = 6); (2) a double locking loop tenorrhaphy with carbon fiber (n = 6); or (3) a double locking loop tenorrhaphy with size 2 nylon suture (n = 6). Clinical assessment, gross evaluation, morphometry, histology, and mechanical testing were performed on two limbs from each treatment group at weeks 6, 12, and 24. At weeks 6 and 12, the unsutured tissue was less mature than the tissue sutured with nylon. By week 24, the carbon fiber repair had breaking stress (mean, 12.5 M Pa) similar to the unsutured repair (mean, 10.6 M Pa). There was necrosis and a granulomatous foreign body reaction around the carbon fiber. The nylon suture repair had significantly greater strength per unit area (mean breaking stress, 20.4 M Pa) because of a smaller area of repair tissue in the gap (mean, 3.6 cm2). At week 24, the nylon suture repair tissue was the most mature with the least inflammation of the three repair methods. A nylon double locking loop suture was the preferred method for equine flexor tenorrhaphy of a tendon gap because of greater breaking stress, histologic maturity, biocompatibility, and the adequate functional and cosmetic outcome.     

Outcome after lacerations of the superficial and deep digital flexor tendons, suspensory ligament and/or distal sesamoidean ligaments in 106 horses

Objective: To report outcome after the surgical treatment of lacerations of the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), suspensory ligament (SL), and/or distal sesamoidean ligaments (DSL) in horses. Study Design: Case series. Animals: Horses (n=106) with lacerations of the SDFT, DDFT, SL, and/or DSL. Methods: Medical records (1988–2002) were reviewed for signalment, limb and tendon/ligament involvement (location and extent of injury, tendon sheath involvement), method of repair, and outcome. Results: The median age of horses was 7 years and the follow‐up time ranged from 1 to 10 years. Fifty‐five percent of horses returned to their previous level of performance, 27% to a lower level, and 18% were euthanatized. Multivariate statistical analysis demonstrated that the number of structures transected had the most significant influence on outcome. No significant association was detected between outcome and tendon sheath involvement, tendon suturing, casting, or limb affected. Fetlock hyperextension was the most significant complication. Conclusions: A high survival rate can be expected after SDFT, DDFT, SL, and/or DSL lacerations in horses, but only 55% of affected horses returned to their previous activity level. The number of structures affected was the major factor determining whether horses returned to an equal level of performance.     

Arthroscopic surgery of the carpal and digital tendon sheaths

Chronic active tenosynovitis of the digital sheath can become increasingly complicated by intrathecal mass and adhesion development, annular ligament constriction, and secondary linear clefting or flattening of the tendons. Endoscopic techniques (tenoscopy) provide a minimally invasive mechanism for thorough digital sheath examination, resection of masses and adhesions, transection of the annular ligament, and debridement of frayed edges after secondary damage. Use of a torniquet, an arthroscope entry point distal to the annular ligament, and instrument portals over the proximal cul-de-sacs of the sheath provide access for tendon and tendon sheath repair. The surgery in advanced cases can be challenging but improvement in work capability and cosmetic appearances are frequently positive. Similarly, a complex form of carpal sheath tenosynovitis can develop from intrusions of bony exostoses and osteochondroma from the radius, tears of the flexor tendons, overextension of the carpus, or fracture of the accessory carpal bone. Tenoscopic examination and debridement within the carpal sheath can assist in rehabilitation. Additionally, the proximal check ligament can be easily transected using carpal sheath tenoscopic techniques. A lateral arthroscope entry proximal to the accessory carpal bone provides access to most clinically relevant regions within the carpal sheath. Instrument portals are made after spinal needle insertion to establish the most appropriate path to the lesion. Removal of bone protrusions and tenosynovial masses, debridement of flexor tendon damage, and release of the carpal retinaculum all offer better chances of improved work capability in a variety of carpal sheath diseases. The examination of the carpal sheath and its contents is more complete than that following open approaches, and a return to rehabilitation exercise programs can be quickly initiated after surgery.     

Use of quantitative analysis of sonographic brightness for detection of early healing of tendon injury in horses

OBJECTIVES: To determine whether quantitative analysis of sonographic brightness could be used to detect healing of an induced injury of the superficial digital flexor tendon in horses and whether rate of healing was influenced by equine recombinant growth hormone. ANIMALS: 8 clinically normal Standardbreds. PROCEDURES: A localized injury was created in the left and right superficial digital flexor tendons of each horse by injection of 2,000 units of collagenase. After injury, 4 horses received equine recombinant growth hormone, a possible promoter of tendon healing. Sonographic images (7.5 MHz) of the flexor tendons and ligaments of the metacarpal region were recorded on videotape prior to injury and weekly for 7 weeks after injury. Images were digitized, and sonographic brightness of tendons and ligaments was calculated. RESULTS: Collagenase-induced injury was sonographically similar to naturally occurring injury. After injury, sonographic brightness of the tendon decreased; after 3 weeks, brightness progressively increased, although by 7 weeks brightness had not returned to preinjury value. Equine recombinant growth hormone had no significant effect on the rate of tendon healing, as evaluated sonographically or at necropsy. CONCLUSIONS AND CLINICAL RELEVANCE: As healing developed, alterations in sonographic brightness of injured tendons coincided with real changes in tendon structure. Quantitative sonographic brightness could be used to accurately monitor healing of equine tendon and ligament injuries and investigate the efficacy of various treatment regimens.     

Kinetics and kinematics of the equine hind limb: in vivo tendon strain and joint kinematics

Strains of the suspensory ligament and deep digital flexor, superficial digital flexor, and long digital extensor tendons in the equine (pony) hind limb were recorded in vivo, using implanted strain gauges consisting of silicone rubber tubes filled with mercury. The relationship between strain gauge signals and tendon strains was obtained from tension-strain tests performed on isolated tendons after death of the ponies. During normal walking, maximal tendon strain (elongation over initial length, relative to the length of the structures at first ground contact) was 3.1% in the suspensory ligament and 3.4%, 2.3%, and 0.3% in the deep digital flexor, the superficial digital flexor, and the long digital extensor tendons, respectively. Changes (that occurred during walking) in the distance from origin to insertion of these musculotendinous structures were computed from limb geometric configuration and limb conformation. Maximal increase in origin to insertion length was 3.1% in the suspensory ligament and 2%, 1.6%, and 1.5% in the deep digital flexor, superficial digital flexor, and long digital extensor musculotendinous structures, respectively. The differences in strain, comparing the entire musculotendinous structure and its tendon, were explained by muscular contraction or relaxation.     

Evaluation of an Autologous Tendon Graft Repair Method for Gap Healing of the Deep Digital Flexor Tendon in Horses

A sutured tenorrhaphy technique that incorporated an autologous tendon graft was compared mechanically and histologically with a sutured tenorrhaphy at 6, 12, and 24 weeks after repair. Tenorrhaphy was performed in the forelimb tendon of the deep digital flexor muscle and the graft was taken from the hindlimb tendon of the lateral digital extensor muscle; one forelimb site included the graft, whereas the other forelimb site was not grafted. Tenotomies were made immediately proximal to the insertion of the accessory ligament into the tendon of the deep digital flexor muscle. Grafted and nongrafted tenorrhaphies were sutured with 2 polydioxanone in a modified double locking-loop pattern. Limbs were supported with a bandage and an extended elevated heel shoe that maintained the dorsal hoof wall angle at 70° to 75°; this support was removed at 12 weeks and dorsal hoof wall angle was maintained at 40° to 45° for the remainder of the study. Gap formation (2.5 ±.3 cm) was evident at all tenorrhaphy sites at 3 days on ultrasound examination. In grafted repairs, the breaking stress was increased ( P <.001) between 6 weeks (2.56 ±.44 MPa) and 12 weeks (17.69 ± 7.68 MPa), with grafted tendon having a greater breaking stress than nongrafted tendon (8.77 ± 2.5 MPa; P <.05). No differences in breaking stress were evident at 24 weeks. At 12 weeks, repair tissue in grafted tendon was histologically more mature, had less cellularity, better fibroblast orientation and more homogeneous collagen matrix than nongrafted tendon. Polydioxanone suture was still evident histologically at 24 weeks and was associated with minimal cellular reaction. Incorporation of an autologous tendon graft improved the mechanical properties and histological quality of the repair tissue in equine flexor tenorrhaphies at 12 weeks but not at 24 weeks after repair.     

An evaluation of two autologous tendon grafting techniques in ponies

OBJECTIVE: To compare the healing and mechanical strength of a multiple split autologous tendon graft (MG) to a whole autologous tendon graft (WG) in the deep digital flexor tendon of ponies. STUDY DESIGN: In vitro evaluation of two different tendon-grafting techniques. ANIMALS OR SAMPLE POPULATION: Six ponies of mixed gender and age. METHODS: Tenotomies performed in forelimb deep digital flexor tendons (DDFT) distal to the insertion of the accessory ligament (AL-DDFT) were repaired with free autologous grafts from the hindlimb lateral digital extensor tendon (LDET). Grafts were either whole (WG) or split into three longitudinal strips (multiple graft, MG). Tendons and graft sites were collected and loaded (2.54 cm/s) to failure at either 4 or 8 weeks after surgery. Cross-sectional area was determined by both impression cast (IC) and an inkblot (IB) method. Tissue maturity and inflammation were evaluated by microscopy. RESULTS: Gap formation was a consistent finding in all repair sites. No statistical differences were found in healing or mechanical variables between MG and WG techniques. The failure stress for the 8-week repairs (15.51 +/- 3.1 MPa IB and 11.73 +/- .77 MPa IC, 16.13 +/- 2.2 MPa IB and 10.22 +/- .76 MPa IC for MG and WG, respectively) were significantly greater (P <.0005) than for 4-week repairs (3.71 +/- 1.7 MPa IB and 2.68 +/- 1.44 MPa IC, 2.81 +/- 1.46 MPa IB and 2.3 +/- 1.7 MPa IC for MG and WG, respectively). The repair tissue was more mature (P <.05) at 8 weeks than at 4 weeks, but there was no significant difference in inflammatory responses at 4 and 8 weeks. CONCLUSIONS: There was a sixfold increase in strength between 4 and 8 weeks of healing, but no significant difference in healing or strength between the MG and WG techniques. CLINICAL RELEVANCE: In ponies, autologous tendon grafting contributes to a strong repair during the early convalescent period, but splitting a tendon graft seemingly offers no appreciable advantage over use of a whole graft.     

Tenovaginoscopic approach to the common digital flexor tendon sheath of adult cattle: technique, normal findings and preliminary results in four clinical cases

The aim of this study was to describe the tenovaginoscopic approach to the bovine common digital flexor tendon sheath (CDFTS). A comparative anatomical, ultrasonographic and endoscopic study was undertaken using 26 healthy cadaver feet from adult dairy cows. Tenovaginoscopy was performed using a rigid, 30° arthroscope (length 18 cm; outer diameter 4mm) enabling a direct view of the synovial cavity and the following structures: digital flexor tendons, digital annular ligaments, lateral and medial pouches, three mesotendons, the vinculum of the superficial digital flexor tendon, and a slot-shaped opening in the manicaflexoria of the hind feet. Additionally, four clinical cases of septic tenosynovitis treated with lavage under tenovaginoscopic control were examined. Tenovaginoscopy represents a feasible, minimally invasive method for the diagnosis and treatment of septic tenosynovitis of the CDFTS, which allows the degree of alterations of the normal structures to be evaluated.     

Effect of sodium hyaluronate in collagenase-induced superficial digital flexor tendinitis in horses.

Superficial digital flexor tendinitis was induced in each forelimb of 8 horses by injecting 4,000 U of collagenase into the midmetacarpal region of the tendon. In each horse, each tendon was treated 24 and 96 hours after the collagenase injection with SC injections of sodium hyaluronate (treated limbs) or an equal volume of 0.9% NaCl solution (control limbs). Exercise was restricted for the first 3 weeks of the study, and a controlled exercise program was instituted for the remainder of the study. Horses were evaluated clinically for lameness, tendon swelling, and midmetacarpal limb circumference. Ultrasonographic examinations were performed regularly (11 examinations/horse) throughout the study, and all horses were euthanatized 12 weeks after collagenase injections. Tendons from 4 horses were harvested for biomechanical testing, and samples were obtained from tendons from the remaining 4 horses for biochemical analysis of collagen. Samples were obtained from all tendons for microscopic evaluation. Significant differences between treated and control tendons were not noticed in any of the variables examined in live horses, although trends toward less lameness in treated limbs and toward better healing on ultrasonographic examination in control limbs were recorded. Significant differences were not noticed in biomechanical or biochemical evaluations, and the only significant (P < 0.05) microscopic finding was more severe inflammation in tendons from treated limbs. This study did not reveal significant benefits of treatment with sodium hyaluronate outside a synovial sheath on tendon repair in collagenase-induced tendinitis.