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.     

The normal anatomical, radiographical and ultrasonographic appearance of the carpal region of one-humped camel (Camelus dromedarius)

The macroscopic, radiographic and ultrasonographic anatomy of the carpal region of eight clinically normal camels (Camelus dromedarius) was determined with the help of a 7.5-MHz linear transducer. At the dorsal aspect of the carpus and distal radius, the extensor carpi radialis, extensor digitorum communis and extensor digitorum lateralis tendons were easily identified. The ulnaris lateralis tendon was observed laterally. The extensor carpi obliqus tendon was identified with difficulty. At the palmar aspect, the flexor carpi radialis, the flexor digitorum superficialis and the flexor digitorum profundus tendons were observed. Other soft structures examined include the lateral collateral ligament and the medial collateral ligament. Ultrasonographic findings correlated with gross anatomy in the dissected limbs. The results of the present study serve as reference data for ultrasonographic investigation of disorders of camel carpus.     

Surgical repair of synovial fistulae between a carpal hygroma,the tendon sheath of the extensor carpi radialis and the antebrachiocarpal joint in a horse

This paper reports the diagnosis and repair of synovial fistulae between a carpal hygroma and both the antebrachiocarpal (ABC) joint and the extensor carpi radialis (ECR) tendon sheath of the left carpus in a 7-year-old gelding. The communication was confirmed using contrast radiography. Arthroscopy visualised the synovial fistulae and aided in the surgical repair. The gelding made a full athletic and acceptable cosmetic recovery.     

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.     

Quantitative analysis of computer-averaged electromyographic profiles of intrinsic limb muscles in ponies at the walk.

The function of several intrinsic muscles of the fore-and hind limbs of 5 ponies walking normally was evaluated via surface electromyography. Electromyographic signals were band-pass filtered, rectified, linear enveloped, and standardized to the stride duration. Mean data from the muscles of the left and right limbs that were obtained from at least 30 strides in 2 recording sessions were recorded as electromyographic signals-time curves. The timing of muscle activity was determined from these graphs. On the basis of the major peaks in the electromyographic signal, muscle functions were identified. In the forelimb, the extensor carpi radialis muscle was involved in extension of the carpus at the end of the swing phase of the stride, and it provided support to flexion of the cubital joint at the beginning of the swing phase. The common digital extensor muscle extended the distal joints of the forelimb at the end of the swing phase. The ulnaris lateralis muscle provided support to extension of the cubital joint at the beginning of the stance phase, and the flexor carpi radialis muscle flexed the carpus at the beginning of the swing phase. The flexor carpi ulnaris muscle extended the cubital joint at the end of the swing phase. In the hind limb, the long digital extensor muscle flexed the tarsus at the beginning of the swing phase and extended the digital joints preceding the stance phase. The deep digital flexor muscle prevented overextension of the distal interphalangeal joint during the stance phase and flexion of the digital joints during the swing phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Traumatic communication of the extensor carpi radialis tendon sheath and antebrachiocarpal joint in two horses

Two horses were examined due to lacerations at the level of the craniodistal antebrachii. Further evaluation of the lacerations revealed communication with the extensor carpi radialis tendon sheath and potentially the antebrachiocarpal joint. Positive contrast arthrography performed via the palmarolateral pouch of the antebrachiocarpal joint was used to diagnose communication with the extensor carpi radialis tendon sheath. Both the joints and tendon sheaths were treated aggressively with surgical debridement and lavage, followed by post operative medical management and rehabilitation. Both horses made a full recovery and are performing in their intended level of use with acceptable cosmetic results. Traumatic communication with the carpal joints should be considered when evaluating lacerations involving the forelimb extensor tendon sheaths.     

Ultrasonographic examination of the carpal region in cattle--normal appearance

The carpal region was examined ultrasonographically in 18 healthy cattle (14 cows, 4 bull calves) and five bovine cadavers in order to determine the normal appearance of the carpal soft tissues using 7.5 MHz linear transducers.The course of the echogenic flexor and extensor tendons over the carpus and the joint spaces interposed between the articular bone surfaces were successfully imaged in all carpi. The palmar vessels were easily visualized in live animals. The lumina of carpal tendon sheaths and the boundaries of the carpal joint pouches could not be defined. Small anechoic fluid filled areas were visualized only at the level of the joint spaces. After experimental filling, the distended synovial cavities were imaged as well demarcated anechoic areas. The cross-sectional diameters of the extensor tendons, width of the palmar joint pouches and intraluminal diameters of the palmar vessels were measured.The results presented serve as reference data for ultrasonographic investigation of disorders of the bovine carpus.     

Die anatomischen Verhältnisse am Karpalgelenk des Geparden (Acinonyx jubatus), verglichen mit jenen der Hauskatze (Felis catus)

The anatomy of the carpal joint of the cheetah (Acinonyx jubatus) was examined in seven specimens using dissection and corrosion casts as well as radiography, and compared to well-known data of the domestic cat (Felis catus). It was found that in the cheetah, as in the domestic cat, the intermedioradial, ulnar and accessory carpal bones, as well as the first, second, third and fourth carpal bones and the sesamoid bone of the abductor pollicis longus muscle, develop in a regular manner. The bones had a similar shape and the ligamentous apparatus was comparable, the most striking differences being the connection of all compartments of the joint cavity and the mediocarpal joint, working as a screw joint. The syndesmosis between the intermedioradial and ulnar carpal bones, instead of a synovial connection, is another adaptation for stabilization of the carpus of the cheetah during locomotion. The joint capsule is little spacious and in all three recesses can be differentiated. The first extends proximally palmar the ulnar carpal bone between the styloid process of the ulna and the accessory carpal bone, the second also extends proximally mediopalmar of the intermedioradial bone, and the largest third recess is located on the dorsal surface and extends proximally, laterally to the inserting tendon of the extensor carpi radialis muscle.     

Epidemiologic, clinical and pathologo-anatomic studies of the inflammation of the carpal joint extensors in cattle

A retrospective study of 24 cases of inflammation of carpal extensors (m. extensor carpi radialis, m. extensor digitorum communis, m. abductor digiti I longus) was conducted. The findings of anamnestic, clinical, and post-mortem investigations are described. Half of the patients were first calf heifers at the ages of 2 1/2 to 3 years. The rest of the animals were older cows (with one exception). In all of the young cows the disease had become apparent within 11 weeks post partum. The most striking clinical finding is the posture of the animals when lying down: the affected forelimbs are extended forward. Palpation reveals a homogeneous firm swelling of the cranial portion of the forearm. Most of the patients also had pododermatitis in hind and/or front legs, and exhibited signs of a systemic reaction in the form of "polysynovitis" and raised serum total protein concentrations. Post mortem examination revealed a hemorrhagic edematous impregnation of the distal part of the radial carpal extensor muscle and particularly of its fascia. The tendon and tendon sheath had unclear contours and were swollen. Histologically the lesions are typical of subacute granulating inflammation. As to the cause, it is assumed that the ailment is a significant complication of some other disease of the locomotion system. Type and localization of the lesions suggest a traumatic etiology. Therapeutic results have been unsatisfactory.     

奶牛正常腕关节的超声影像学的研究

采用7．5MHz的线扫探头对4只奶牛尸体腕关节和6头奶牛的8个腕关节的正常结构进行了超声检查。一般骨骼的回声为光环或光线，关节囊呈明显的液性暗区，腱质呈实性强回声。桡腕关节囊、腕间关节囊及囊内绒毛可见。腕关节的腕桡侧伸肌腱、臂二头肌腱、指浅屈肌腱和指深屈肌腱都可清楚地看到，腕关节外侧由于腱比较细，加上侧副韧带多，在声像图上较难辨别其结构，腕关节内侧超声声像图不清楚。     

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.     

Use of magnetic motor-evoked potentials in horses with bilateral hind limb ataxia

OBJECTIVE: To determine the usefulness of magnetic motor-evoked potentials (MMEPs) for assessing the integrity of the cervical, thoracic, and thoracolumbar spinal cord in horses with bilateral hind limb ataxia. ANIMALS: 9 horses and 1 donkey with bilateral hind limb ataxia of various degrees. PROCEDURE: The motor cortex was stimulated magnetically, and MMEPs were recorded bilaterally from the extensor carpi radialis and cranial tibial muscles. RESULTS: In 5 horses and 1 donkey, MMEPs with normal onset latencies and peak-to-peak amplitude were recorded from the extensor carpi radialis muscles, whereas abnormal onset latencies and peak-to-peak amplitudes were recorded from the cranial tibial muscles. In these animals, a spinal cord lesion in the thoracic or thoracolumbar segments was suspected. In 4 horses, onset latencies and peak-to-peak amplitude of MMEPs recorded from the extensor carpi radialis and cranial tibial muscles were abnormal. In these horses, a cervical spinal cord lesion was suspected. CONCLUSIONS AND CLINICAL RELEVANCE: Transcranial magnetic stimulation can be considered a valuable diagnostic tool for assessing the integrity of the spinal cord, and MMEPs may be used for differentiating thoracic or thoracolumbar spinal cord lesions from mild cervical spinal cord lesions that cause ataxia in the hind limbs only.     

The treatment of transection of the extensor carpi radialis muscle as a result of a lacerating wound in a horse

A 16 month old filly was presented with the complaint of a severe laceration to the right foreleg with resultant transection of the extensor carpi radialis. Normal principles of wound treatment were followed and a bandage and splint were used for support and immobilization. The return to partial function of the damaged extensor carpi radialis was evidenced by resolution of the wound and an improvement in the patient's gait four months after the time of injury.     

Prevalence of carpal fractures in thoroughbred and standardbred racehorses

The prevalence of carpal fractures was determined for 211 thoroughbred and 75 standardbred racehorses. Statistically significant differences were found in the location of fractures between the 2 breeds. In the thoroughbred and standardbred groups, total fractures (460) were distributed nearly equally between the left (224) and right (236) carpi. The most common site of fracture in the thoroughbred group was the distal aspect of the radiocarpal bone (112), whereas the most common site of fracture in standardbred horses was the proximal surface of the third carpal bone (61). Slab fractures were more common in the right carpus of thoroughbred horses (29 right/11 left), but were distributed equally between the left (11) and right (11) carpi of the standardbred group. Fractures of the distal border of the radius and intermediate carpal bone were more common in the left carpi of the thoroughbred group and were relatively uncommon among standardbred horses. Fractures within the intercarpal joints (313) were more common than those within the radiocarpal joints (147) in thoroughbred and standardbred horses.     

Radial-intermediate Carpal Bone Fusion in a Horse

The radial carpal and intermediate carpal bones were found to be fused in a four year old Quarterhorse stallion having a subtle forelimb lameness. Clinical examination, diagnostic local anesthesia, radiography and arthroscopy were used to arrive at the diagnosis. A cause could not be established, although perinatal deformation of cartilagenous carpal bone templates is suspected. A similar case of carpal bone fusion was found among carpi collected for an anatomical study, indicating this condition may be more common than expected. Clinicians should carefully evaluate the flexed lateral view of the carpus for proximal movement of the intermediate and ulnar carpal bones in young horses presented for carpal lameness. The significance of this condition will remain uncertain until its incidence and relationship to lameness are better defined.     

Surgical Anatomy for Desmotomy of the Accessory Ligament of the Superficial Digital Flexor Tendon (Proximal Check Ligament) in Horses

Dissections were performed to study the surgical anatomy for desmotomy of the accessory ligament of the superficial digital flexor tendon (proximal check ligament [PCL]). The surgical approach was initiated by incising the skin cranial to the cephalic vein and caudal to the distal radius. A palpable foramen in the antebrachial fascia that transmits a branch of the cephalic vein was used to advance deeper dissection. After the antebrachial fascia was incised, the fan-shaped PCL was exposed by retracting the en-sheathed tendon of the flexor carpi radialis muscle caudally. Desmotomy was performed gradually to avoid severing branches of the palmar carpal rete that pervade the ligament. Complete transection was evidenced by visualization of the membranous roof of the carpal canal distally, the muscle belly of the radial head of the deep digital flexor centrally, and loose areolar connective tissue along the caudal radius proximally. The vessels of the palmar carpal rete were visible coursing between the severed edges of the PCL. This report highlights relevant anatomic landmarks to facilitate an accurate desmotomy.     

Anatomical features of the carpal flexor retinaculum of the horse

This study aims to elucidate the topographical anatomy of the carpal flexor retinaculum or palmar anular carpal ligament (PACL) in the horse. Ten specimen of the carpus of five healthy horses were studied by dissection in layers. Slices of 5 mm in thickness facilitated observation of the soft tissues. The superficial layer of the PACL subdivides into five compartments: one for the palmar nerve and the arterial and venous branches, one for only the radial artery, one for the radial vein, and one for the tendon of the radial carpal flexor muscle, and finally for the deep layer that supports all tendinous structures located palmar to the carpus, as well as the median artery and palmar medial nerve. The sections of the segmented PACL that are affected by carpal canal syndrome may vary with the aetiology of the space-occupying process. Precise anatomical knowledge of the structures may help in understanding the pathological processes and determining the most appropriate therapy.     

Accessory carpal bone displacement in two dogs.

The diagnosis and treatment of luxation of the accessory carpal bone in a racing greyhound, and subluxation of the same bone in a lurcher, are described. The injury in the lurcher occurred in both carpi, but on separate occasions. Both dogs had severe thoracic limb lameness with marked carpal swelling. The diagnosis of luxation was obvious from carpal radiographs. The subluxations were difficult to detect on palpation, but were suspected and confirmed on exploratory surgery, which showed an avulsion of the lateral support structures of the accessory carpal bone from the distal ulna. Pancarpal arthrodesis with accessory carpal bone excision undertaken in the greyhound was successful. Following repair of the torn ligaments, the lurcher returned to full activity without lameness before sustaining the same injury to the other carpus. The anatomy of the accessory carpal support structures and the aetiology of the injuries are discussed.     

Bilateral distal radial epiphysectomy and pancarpal arthrodesis for correction of complex carpal deformities in an American Miniature horse

A 9‐day‐old American Miniature horse was referred for evaluation and treatment of congenital bilateral carpal deformities. Clinical examination revealed a combination of flexural, angular and rotational deformities affecting both carpi. Radiographic evaluation of both forelimbs revealed malformation of the distal radial epiphysis accompanied by flexural contracture and external rotation of the limb distal to the antebrachial carpal joint. Conservative therapy was attempted with splints and bandages and failed to result in improvement. Surgical intervention was elected and a bilateral distal radial epiphysectomy and pancarpal arthrodesis performed. Fourteen months later the mare was turned out to pasture and ambulating well.     

Fractures of the carpus in racing thoroughbreds of the Japan Racing Association: Prevalence, location, and current modes of surgical therapy

From 1985 through 1994 approximately 39,800 Thoroughbred horses competed in over 3,400 races each year conducted by the Japan Racing Association (JRA). During this time the prevalence of fractures incurred during racing was 1.99, and 0.09% during training. Of these, 0.32% of the horses during racing died or were humanely destroyed as a direct result of their injuries. During 1994, 1,837 fractures occurred. The cuboidal bones of the carpus and the distal end of the radius accounted for 33.5% of all recorded fractures, with 47.4% of these occurring during racing and 24.2% occurring during training. The most common sites of fracture within the carpus were the distal end of the radius, the third carpal bone, and the radial carpal bone accounting for 35.3, 35.2, and 29.5% of fractures, respectively. Of these, 86/7% of osteochondral fractures occurred on the dorsal aspect of the cuboidal bones. At racing speed, characteristic fractures of the carpus are relatively common in race horses.Since 1991 in Japan, arthroscopic surgery has been the treatment of choice for the removal of carpal joint osteochondral fragments. Of all horses having arthroscopic surgery (n=155), 68.4% of these horses returned to race 9 months after surgery. Of all horses having osteochondral fractures of the distal end of the radius, radial carpal, and third carpal bones treated with arthroscopic surgery in 1993 (n=97) 52.6%, 60.0%, and 55.6% respectively, returned to race and competed at the same level of competition or higher compared with pre-operative racing performance. Arthroscopic surgery, as adapted by the JRA, is a useful technique for the treatment of carpal bone fractures in race horses; however, following surgery some horses had chronic arthritic changes associated with the surgical site. This suggests that the surgical methods and post-operative training program have to be re-evaluated.The objectives of this paper are to describe the prevalence, location, post-operative complication and racing performance for horses having cuboidal carpal bone fractures in racing Throughbreds of JRA.