Digital extensor tendon lacerations in horses: A retrospective evaluation of 22 cases

Hospital records of 22 horses referred to the Royal Veterinary and Agricultural University (RVAU) of Copenhagen between January 1, 1990 and December 31, 1993 for treatment of digital extensor tendon laations were reviewed, and follow-up information on final outcome was collected to determine whether any injury or treatment factors could be associated with the outcome.

Mean age of the horses was 5.2 years (range, 1 to 20 years), and follow-up time ranged from 1 to 5 years after injury. In 21 (95%) of the horses, injury involved the hind limbs. Eleven (50%) horses returned to their original or intended level of use. Eighteen (82%) horses had no signs of lameness. There was no statistically significant correlation between outcome and elapsed time from injury to treatment, type of injury, treatment variables, or wound healing in the present study, and these findings support previous reports.

It was concluded that horses with digital extensor tendon lacerations had a favorable prognosis for return to riding soundness and a fair prognosis for return to their original or intended level of use. Tendon suturing and primary wound healing did not improve the prognosis.     

Surgical Management of Multiple Ligamentous Injuries of the Feline Stifle Joint: Case Report

We report a case of complete rupture of the tendon of origin of the long digital extensor at the myotendinous junction, with concurrent ruptures of the posterior cruciate and lateral collateral ligaments in the stifle joint of a cat. Stabilization was accomplished by direct suturing of the long digital extensor injury, imbrication of the joint capsule and lateral retinacular fascia, and creation of a synthetic lateral collateral ligament     

Tenoscopic removal of a protruding osteophyte as a treatment for chronic common digital extensor tendinopathy and associated tenosynovitis

This report describes an adult Quarter Horse gelding that was presented for evaluation of chronic tenosynovitis of the right common digital extensor tendon sheath. Radiographic and tenoscopic evaluation confirmed the presence of a periarticular osteophyte from the third metacarpal bone protruding into the common digital extensor tendon sheath. Tenoscopic surgical resection of the osteophyte and debridement of the affected tendon resolved the tenosynovitis and associated right forelimb lameness. Osteophytes in this location can be a source of focal traumatic tendonitis of the common digital extensor tendon which can lead to a chronic tenosynovitis of the common digital extensor tendon sheath. Tenoscopic debridement and lavage is a viable treatment option for chronic nonseptic common digital extensor tendinopathy and associated tenosynovitis.     

A review of tendon injury: Why is the equine superficial digital flexor tendon most at risk?

Tendon injury is one of the most common causes of wastage in the performance horse; the majority of tendon injuries occur to the superficial digital flexor tendon (SDFT) whereas few occur to the common digital extensor tendon. This review outlines the epidemiology and aetiology of equine tendon injury, reviews the different functions of the tendons in the equine forelimb and suggests possible reasons for the high rate of failure of the SDFT. An understanding of the mechanisms leading to matrix degeneration and subsequent tendon gross failure is the key to developing appropriate treatment and preventative measures.     

ULTRASONOGRAPHY OF THE EQUINE CRUS

Ultrasonography was used to delineate the sonographic anatomy of the equine crus, emphasizing the peroneus tertius muscle and the Achilles tendon. The cross-sectional gross anatomy was studied in 6 cadaveric limbs. Using a 5.5 MHz mechanical sector scanner the examined Achilles tendon and per- oneus tertius muscle were easily identified as hyperechoic structures in 10 limbs of normal live horses. In 4 lame horses diagnostic ultrasound aided the diagnosis of peroneus tertius rupture, haematoma of the lateral digital extensor muscle and the presence or absence of Achilles tendon injury associated with intertendinous calcaneal bursitis.     

Kinetics and kinematics of the equine hind limb: in vivo tendon loads and force plate measurements in ponies

Loads on the suspensory ligament, deep digital flexor tendon, superficial digital flexor tendon, and long digital extensor tendon of the equine hind limb were determined in ponies by use of implanted strain gauges consisting of silicone rubber tubes filled with mercury. Recordings were made simultaneously with force plate measurements and high-speed film recordings while the ponies were walking. The relationship between strain gauge signals and tendon loads was obtained from tension-strain tests performed after death of the ponies. The suspensory ligament and the 2 digital flexor tendons were loaded during the stance phase, and the extensor tendon was loaded mainly during the swing phase. The loading pattern of the suspensory ligament, with peak loads of 4.6 N/kg of body weight, correlated well with the vertical component of the ground reaction force. Maximal loading of the deep digital flexor tendon was observed during the second half of the stance phase, with peak values of 6.7 N/kg. The superficial digital flexor tendon was loaded maximally at the beginning of the stance phase, with a peak load of 4.1 N/kg, and the long digital extensor tendon was loaded maximally during the swing phase, with a peak load of 0.3 N/kg. Recordings made from this procedure for calibration of the strain gauge signals to tendon load and tendon strain, in combination with the force plate measurements, enabled verification of the results by torque analysis of the lower portion of the hind limb, using the vector of the ground reaction force, limb conformation, and limb geometric configuration. Torque analysis of the lower extremity indicated that the determined tendon loads were in agreement with the recorded ground reaction forces.     

Comparison of four techniques of arthrocentesis of the lateral compartment of the femorotibial joint of the horse

Reasons for performing study: Clinical experiences indicate that centesis of the lateral compartment of the femorotibial joint is often unsuccessful. Objective: To determine the accuracy of 2 published and 2 unpublished techniques of centesis of the lateral compartment of the femorotibial joint. Hypothesis: It was hypothesised that a drug can be administered into the lateral compartment of the femorotibial joint via a diverticulum of this joint that surrounds the medial aspect of the long digital extensor tendon and that this technique is more accurate than described techniques of centesis of this compartment. Methods: Twenty‐four stifles of 12 horses were divided equally into 4 groups and a radiocontrast medium injected into the lateral compartment of the femorotibial joint of each group using a hypodermic needle inserted: 1) caudal to the lateral patellar ligament and proximal to the tibial plateau, 2) caudal to the long digital extensor tendon and proximal to the tibial plateau, 3) between the long digital extensor tendon and bone of the extensor groove of the tibia or 4) directly through the long digital extensor tendon until it contacted bone. Twelve veterinary students who had no experience using any of these techniques performed the injections. Accuracy of each technique was determined by examining radiographs obtained after injecting the contrast medium. Results: The most successful technique for arthrocentesis was by inserting a needle through the long digital extensor tendon. This approach was successful in all attempted cases, whilst other techniques had lower rates of success. Conclusions: The lateral compartment of the femorotibial joint can be accessed accurately by inserting a needle through the long digital extensor tendon as it lies within the extensor groove. Other techniques may not be as accurate for clinicians inexperienced in arthrocentesis of the lateral compartment of the femorotibial joint.     

The management of tendon injuries in dogs

An account is provided of the management of 68 dogs with tendon injury. Of the 33 with Achilles rupture, 23 sustained tendon severance, seven had disrupted the gastrocnemius muscle/tendon junction, and in three an attachment of the gastrocnemius was avulsed. The standard operative procedure comprised fixing the hock in extension with a screw, and exploring the damaged structures with a view to repair and the introduction of carbon fibre implants. The majority regained normal limb use and the main complications concerned loosening or fracture of the screw. The 32 with digital flexor tendon severance had cuts, on a fore foot in nine and a hind foot in 23. Exploration and reconstruction were routinely practised and carbon fibre implants were frequently used. The standard of recovery was good in those dealt with fresh but was less satisfactory in chronic cases. The two dogs with digital extensor tendon and the one with flexor carpi ulnaris tendon severance responded well to repair.     

Tendon Transfer for Treatment of Peroneal Nerve Paralysis in a Dog Report of a Case

A six-year-old male Labrador cross was left with a sensory and proprioceptive deficit in the right hind paw after recovering from a severe case of warfarin poisoning. Palliative treatment in the form of protective devices, casts and bandages was not successful. A chronic ulcerative infection developed with enlargement of the popliteal lymph node requiring medical treatment. A conscious proprioceptive deficit in the right hind leg only was consistent with a peroneal or ischiatic nerve deficit. A surgical procedure to shorten the long digital extensor was not satisfactory. A second precedure, the transfer of the long digital flexor tendon to the long digital extensor tendon provided an excellent end result.     

Resection of the common digital extensor tendon in a gelding

A four-year-old gelding was lame owing to a chronic septic common digital extensor tendon and sheath. The horse had been treated by open surgical lavage but the sepsis had recurred after three months. Physical, ultrasonographic, cytological and histological examinations confirmed chronic septic tenosynovitis and tendonitis. The entire intrathecal component of the common digital extensor tendon was resected under general anaesthesia and the synovial lining of the sheath was ablated. Postoperatively the horse regained good limb function and became sound.     

Evaluation of computed tomographic anatomy of the equine metacarpophalangeal joint

OBJECTIVE: To determine the detailed computed tomography (CT) anatomy of the metacarpophalangeal (MCP) joint in healthy horses. SAMPLE POPULATION: 10 cadaveric forelimbs from 10 adult horses without orthopedic disease. PROCEDURES: CT of the MCP joint was performed on 4 forelimbs. In 1 of the limbs, CT was also performed after intra-articular injection of 30 mL of contrast medium (40 mg of iodine/mL). Transverse slices 1-mm thick were obtained, and sagittal and dorsal planes were reformatted with a slice thickness of 2 mm. The CT images were matched with corresponding anatomic slices from 6 additional forelimbs. RESULTS: The third metacarpal bone, proximal sesamoid bones, and proximal phalanx could be clearly visualized. Common digital extensor tendon; accessory digital extensor tendon; lateral digital extensor tendon; superficial digital flexor tendon (including manica flexoria); deep digital flexor tendon; branches of the suspensory ligament (including its attachment); extensor branches of the suspensory ligament; collateral ligaments; straight, oblique, and cruciate distal sesamoidean ligaments; intersesamoidean ligament; annular ligament; and joint capsule could be seen. Collateral sesamoidean ligaments and short distal sesamoidean ligaments could be localized but not at all times clearly identified, whereas the metacarpointersesamoidean ligament could not be identified. The cartilage of the MCP joint could be assessed on the postcontrast sequence. CONCLUSIONS AND CLINICAL RELEVANCE: CT of the equine MCP joint can be of great value when results of radiography and ultrasonography are inconclusive. Images obtained in this study may serve as reference for CT of the equine MCP joint.     

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.     

Para-articular osteochondroma with intersynovial fistula between the common digital extensor sheath and carpometacarpal joint

A 7-year-old Holsteiner gelding was presented with a left common digital extensor sheath effusion of one-year's duration. Radiographic examination revealed two extra-articular mineralised bodies adjacent to the dorsolateral carpometacarpal joint. Ultrasonography confirmed an intrathecal location of one mineralised body in the common digital extensor sheath, palmar fraying of the common digital extensor tendon and tenosynovitis. Ultrasound could not confirm whether the second mineralised body was intrathecal or located external to the common digital extensor sheath. Common digital extensor tenoscopy facilitated removal of both mineralised bodies and revealed a fistula communicating with the carpometacarpal joint. The mineralised bodies, initially thought to be synovial osteochondromas, were histologically identified as para-articular osteochondromas. There are no previously published reports of para-articular chondroma/osteochondroma in the horse. Despite surgical removal of the para-articular osteochondromas, concern for future extensor sheath distension remained given the communication between the carpometacarpal joint and common digital extensor sheath.     

The Use of a Tendon Transfer for the Treatment of a Traumatic Sciatic Nerve Paralysis in the Dog

A case of a traumatic sciatic nerve paralysis was successfully treated with the transfer of the long digital extensor tendon of origin to the vastus lateralis muscle after a portion of the latter had been separated from its insertion on the patella. A second procedure was necessary to shorten the distal tendon of the long digital extensor muscle to create the proper tension needed to fully extend the digits. Within 11 weeks after surgery the dog was successfully returned to training and field trial competition. Viability of the transfer was further demonstrated by electrical stimulation of the vastus lateralis one year later.     

Factors affecting outcome of extensor tendon lacerations in the distal limb of horses. A retrospective study of 156 cases (1994-2003)

Distal limb lacerations are common injuries in horses, with a better prognosis reported for extensor tendons lacerations compared to flexor tendons lacerations. The objective of the present study was to determine the influence of type and location of injury, modalities of treatment and post surgical complications on the outcome of extensor tendon lacerations. The medical records of 156 horses surgically treated for extensor tendon lacerations over a 10-year period were analysed retrospectively. Information was obtained for 124 horses with a minimum of 18 months follow-up. Statistical analysis was performed on 129 horses (five horses were euthanatized during hospitalization) in order to determine factors affecting outcome. Seventy-four percent of the horses returned to soundness, 17% had moderate gait impairment and 9% remained lame. Approximately 60% of the sports horses returned to an equal or higher level of performance, and 17.5% returned to a lower level. In the multivariate statistical analysis, the only significant factor that favourably influenced outcome was complete suture of the wound. A significant association could not be detected between outcome and absence of a functional extensor tendon, The most important post-surgical complication was extensive scarring of the wound. The present results report outcome of extensor tendon lacerations in a large number of horses and outline the importance of primary wound healing in order to avoid major scarring with potential functional consequences.     

ULTRASONOGRAPHY OF THE DORSAL AND LATERAL ASPECTS OF THE EQUINE CARPUS: TECHNIQUE AND NORMAL APPEARANCE

The normal ultrasonographic appearance of the dorsal and lateral soft tissue structures and anatomic landmarks of the equine carpus useful in clinical imaging are described.
Both limbs of 5 cadavers and 5 clinically sound adult horses were imaged using a 7.5 MHz sector transducer. At the dorsal aspect of the carpus and distal radius, the extensor carpi radialis- and the common digital extensor tendon and their tendon sheaths were easily identified. These two tendons are the most prominent structures in this region. Smaller and more difficult to identify are the tendon and tendon sheath of the extensor carpi obliquus-, the lateral digital extensor- and the ulnaris lateralis muscle. The ultrasonographic appearance and course through the carpal region of the tendons and tendon sheaths mentioned are described. Other soft tissue structures examined include the lateral collateral ligament, the carpal joint capsule and the distal articular cartilage of the radius. Ultrasonographic findings correlated well with gross anatomy in the cadavers limbs.     

Experimental Evaluation of Tendon Transfer for the Treatment of Sciatic Nerve Paralysis in the Dog

The sciatic nerve was surgically transected in 6 dogs. The resulting dysfunction and the positive effects of a transfer of the tendon of the vastus lateralis muscle to the long digital extensor muscle were evaluated, alone and in combination with a talocrural arthrodesis. Two dogs that received both arthrodesis and tendon transfer showed the greatest improvement in gait.     

PRESUMPTIVE TENOSYNOVIAL OSTEOCHONDROMATOSIS IN A HORSE

A 5 year old Arabian mare was evaluated for a non-painful swelling located dorsal to the right carpus which had been present for 2 years. Radiographically, multiple mineralized bodies were identified dorsal to the distal radius and carpus in the region of the tendon sheath of the extensor carpi radialis muscle. The radiographic appearance of the carpal bones was within normal limits. On ultrasound examination, multiple hyperechoic foci with posterior shadowing were seen adjacent to the extensor carpi radialis tendon. There was minimal distension of the tendon sheath and no abnormalities within the substance of the extensor carpi tendon were identified. Considering the radiographic and sonographic findings, a presumptive diagnosis of tenosynovial osteochondromatosis was made. Histological confirmation of this diagnosis was not obtained as the owner declined further diagnostic evaluation.     

Unusual soft tissue orthopaedic problems in the dog

Single cases of supraspinatus and infraspinatus muscle contracture in working sheep-dogs are reported. Both cases showed characteristic abnormal forelimb posture and were successfully treated by complete section of the affected muscle. Three cases of anteromedial shoulder luxation with damage to the biceps brachii tendon are also described. In two of these the tendon was completely severed. The integrity of the biceps tendon is important in maintaining shoulder joint stability and should be inspected when surgical reduction of shoulder dislocations is carried out. Repair of the tendon, if severed, is important. Three cases of lameness associated with tendon displacement are considered i.e. slipping of the biceps brachii, long digital extensor and superficial digital flexor tendons. In two cases the displacement was prevented by the insertion of mattress wire sutures to form a 'lid' over the tendon.