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.     

Carpal hyperflexion in a growing dog following neural injury to the distal brachium

A three-month-old dobermann was presented with hyperfiexion of the right carpus. The abnormality had evolved over a three-week period, following circumferential soft tissue trauma to the distal brachium. The carpal joint angle measured at the limit of passive extension was 105 degrees compared with 175 degrees for the left carpus, and prevented placement of metacarpal and digital pads on the ground. Neurological examination revealed marked atrophy of the carpal extensors, an absent extensor carpi radialis reflex and moderate atrophy of the carpal flexors. Spontaneous electromyographic activity consistent with denervation was recorded in the carpal extensor and flexor muscles. Surgical exploration of the distal radial nerve disclosed a region of fibrosis enmeshing the deep branch of the radial nerve. Following relief of the entrapped nerve, carpal hyperflexion, muscle atrophy and the extensor carpi radialis reflex deficit gradually resolved over four months. It is suggested that, In the rapidly growing limb, myoneural dysfunction Induced by trauma was the underlying pathophysiological mechanism for carpal hyperflexion.     

Ultrasonographic examination of the carpal canal in dogs

The aim of this study was to determine the course of the median nerve and its adjacent structures in the carpal canals of 8 healthy dogs by using high-frequency transducers. Before performing ultrasonography, the transverse and posteroanterior diameters as well as the perimeter of the carpus were measured at just proximal to the side of the carpal pad. The anatomical structures were then determined at two levels of the carpal canal, which were named the proximal and distal levels, on the transverse sonograms. The cross-sectional areas, perimeters and the transverse and posteroanterior diameters of the median nerve were measured at these levels. Although all the measurements were larger at the proximal level, significant differences between the proximal and distal levels were determined for the cross-sectional area, the perimeter and the transverse diameter of the median nerve. On the transverse sonogram, the deep digital flexor tendon was seen in almost the center of the carpal canal like a comma shape and also it had a small concavity on the caudal side. The superficial digital flexor tendon was seen as an ovoid shape on the transverse sonograms and it was located nearly at the posterior side of the carpal canal. Both tendons were seen as intermediate-grade echogenic structures. The median artery was located inside of the concavity of the deep digital flexor tendon. Also, the median nerve was seen at the posteromedial side of the median artery. As a result of this study, the cross-sectional areas of the median nerve ranged between 1.01-2.68 mm² at the proximal level and between 0.93-1.91 mm² at the distal level.     

Carpal hyperextension in a Percheron mare caused by a palmar carpal ligament tear

A Percheron mare was presented for acute, severe lameness and marked swelling of the right forelimb after being cast. The mare was initially diagnosed with cellulitis of the forelimb but as her condition improved and the affected limb was able to bear more weight it became apparent that the limb was hyperextended at the level of the carpus. Widening of the palmar aspect of the middle carpal joint was observed radiographically. During ultrasonographic examination, excessive fluid in the carpal sheath and perithecal swelling were noted and tearing of the palmar carpal ligament was suspected. A dynamic brace was fabricated to prevent hyperextension of the carpus. After discontinuation of systemic antibiotics, the mare became febrile and forelimb lameness worsened. Cytology of fluid from the middle carpal joint confirmed joint sepsis and the mare was anaesthetised for arthroscopic examination. A tear in the palmar carpal ligament, characterised by focal fibre disruption and fibrillation, was identified during arthroscopic and tenoscopic examination. Communication between the carpal flexor tendon sheath and middle carpal joint was identified during these procedures. Both the middle carpal joint and carpal flexor tendon sheath were lavaged with physiological saline solution. Post operatively, swelling and lameness slowly resolved. Four months after discharge, the mare was sufficiently sound to be maintained at pasture. Viewed from its lateral aspect, the limb no longer appeared to be hyperextended from the carpus.     

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.     

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.     

MAGNETIC RESONANCE ANATOMY OF THE CARPUS OF THE HORSE DESCRIBED FROM IMAGES ACQUIRED FROM LOW‐FIELD AND HIGH‐FIELD MAGNETS

Cadaver carpi of 30 mature horses with no history of carpal or proximal metacarpal pain were examined using low‐field (0.27 T) and high‐field (1.5 T) magnetic resonance imaging (MRI). Normal MRI anatomy in transverse, sagittal, and dorsal plane images was determined by comparison with anatomical specimens and standard texts. Subchondral bone and cortical bone thickness measurements were obtained from standardised sites. There was variable subchondral bone thickness in the radius and carpal bones; subchondral bone thickness was consistently larger at dorsal compared with palmar sites in the proximal row of carpal bones. The endosteal surface of the subchondral bone was smooth. The shape of the ulnar carpal bone was variable and one or more small osseous fragments were identified palmar to the bone in 5/30 limbs. There was no evidence to suggest that these were pathological fractures or avulsions of the lateral palmar intercarpal ligament. The amount of muscle tissue in the superficial and deep digital flexor tendons in the proximal aspect of the carpus varied, but none was present at the level of the middle carpal joint and distally. Several structures could be evaluated that cannot be imaged using radiography, ultrasonography, or arthroscopy, including the transverse intercarpal ligaments, the radiocarpal ligament, the short palmar carpal ligaments, and the carpometacarpal ligaments. Anatomical variations not previously described were identified, including the layers of the medial aspect of the carpal fascia. Knowledge of the variation in MRI appearance of the carpus of nonlame horses is helpful for interpretation of MR images of lame horses.     

Arthroscopic approaches to the palmar aspect of the equine carpus

OBJECTIVE: To identify sites for arthroscopic access to the palmar aspects of the antebrachiocarpal (AC) and middle carpal (MC) joints, and describe visible carpal bone surfaces for each approach. STUDY DESIGN: Prospective experimental study. ANIMALS: Equine carpi: 16 cadavers, 8 live horses. METHODS: A latex model was used to identify possible sites for arthroscopic access to the palmar aspects of the AC and MC joints. Carpi (n = 24) were examined arthroscopically and arthroscopic access sites and visible carpal bone surfaces were described. RESULTS: Arthroscopic approaches and instrument portals were developed for the medial and lateral aspects of the palmar pouches of the AC and MC joints. The palmar surface of the radial carpal bone and radius, and the dorsal articular surfaces of the accessory carpal bone, could be viewed using palmar approaches to the AC joint. The palmar aspect of the radial, third and second carpal bones (medially) and ulnar and fourth carpal bones (laterally) could be observed using a palmar approach to the MC joint. CONCLUSIONS: Arthroscopic access, using separate medial and lateral portals to the AC and MC joints, allowed assessment of portions of the caudodistal radius, the palmar surfaces of the radial, ulnar, second, third and fourth carpal bones, and the dorsal aspect of the accessory carpal bone. CLINICAL RELEVANCE: Arthroscopic approaches to the palmar aspect of the carpus could be used to remove fracture fragments, and to assess the medial palmar intercarpal ligaments.     

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.     

Surgical treatment of carpal flexural deformity in 72 horses

Carpal flexural deformities (CFD) are frequently encountered in the horse, with both congenital and acquired forms described. The success of surgical correction of CFD, both in terms of the ability to achieve a straight palmar carpal angle and the impact on future athletic performance, requires further investigation. OBJECTIVE: To report the surgical management and outcome of treatment of flexural deformity of the carpus in 72 horses up to 12 months of age. METHOD: Information was obtained from the medical records of horses surgically treated for CFD and through follow-up contact with owners. At the time of examination each case was graded on the severity of the flexural deformity as grade 1, 2, or 3, in order of ascending severity. Surgical treatment consisted of tenotomy of the ulnaris lateralis and flexor carpi ulnaris muscles. Re-assessment of the palmar carpal angle was made in the immediate postoperative period and again from at least 8 months after surgery via telephone contact with owners and/or breeders. A successful outcome was defined as achievement of a straight palmar carpal angle. Long term outcome was assessed in terms of fullfilment of intended use for horses reaching 3 years of age at the time of the study. RESULTS: A total of 135 surgical procedures were performed on 72 horses. A successful outcome was recorded in 111 limbs (82%). Excluding cases lost to follow-up, surgical correction was more successful in restoring a straight palmar carpal angle in grade 1 limbs (25/25, 100%) compared to grade 2 limbs (78/87, 89%) and grade 3 limbs (8/14, 57%). For those horses that had reached 3 years of age, 26 of 36 Thoroughbreds started in a race (72%) and 12 of 14 non-Thoroughbreds fulfilled their intended use (86%). CONCLUSION: Tenotomy of the ulnaris lateralis and flexor carpi ulnaris tendons for treatment of grade 1 and 2 CFD's has an excellent prognosis for restoration of a straight palmar carpal angle and for intended athletic pursuit of the horse. In cases of grade 3 CFD, the prognosis following surgery is guarded, especially in neonates. Horses treated in this study were up to 12 months of age, indicating that this deformity may not always be self-limiting as previously thought, and treatment may be required for successful resolution of flexural deformity of the carpus in older animals. The results of this study will help veterinarians to make recommendations regarding the surgical treatment of CFDs.     

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.     

Macroanatomic investigations of the blood supply of thoracic limb of Kangal dogs

In this study, the arterial supply of the thoracic limb was investigated in Kangal dogs. Twelve adult healthy Kangal dogs of either sex were used. Latex was injected into the common carotid artery, and then the axillary artery was dissected. The axillary artery is a continuation of the subclavian artery and supplies the thoracic limb in Kangal dogs. The axillary artery gave off a deltoid branch and external thoracic, lateral thoracic, and subscapular thoracic arteries in its course along the thoracic wall. The axillary artery continues distally as the brachial artery in the arm. The brachial artery gives rise to the cranial humeral circumflex, deep brachial, bicipital, ulnar collateral, superficial brachial, transverse cubital, and common interosseus arteries. It continues as the median artery after giving off the common interosseus artery. It was observed that the deep antebrachial artery arose from the median artery at the proximal third of the forearm. In the distal third of the forearm, the median artery divided into the palmar carpal and dorsal carpal branches. The deep palmar branch of the radial artery and deep branch of the palmar branch of the caudal interosseus artery form the deep palmar arch. The median artery joined the superficial branch of the palmar branch of the caudal interosseus artery to constitute the superficial palmar arch. The radial artery and cranial interosseus artery contributed to the dorsal carpal rete. The ulnar artery contributed to the formation of the deep and superficial palmar arches.     

Incomplete Longitudinal Fracture of the Proximal Palmar Cortex of the Third Metacarpal Bone in Horses

Seven horses, 2 to 4 years of age, were examined because of moderate-to-severe forelimb lameness, mild effusion of the middle carpal joint (3 horses), and pain on palpation of the origin of the suspensory ligament (4 horses). The lameness was abolished by anesthetic infiltration of the middle carpal joint in six horses. In four of them, a high palmar nerve block also abolished the lameness. A linear radiolucency in the proximal end of the third metacarpal bone (McIII) was interpreted as an incomplete longitudinal fracture. In one horse, distinct intramedullary sclerosis limited to the palmar cortex was indicative of an incomplete fracture confined to the palmar cortex. No osteoproliferative lesions were identified on the dorsal cortex of any of the horses. Surgical treatment with cortical screws in lag fashion accompanied by a rest period was successful in one horse. In four horses, rest for at least 3 months resulted in clinical soundness. In two horses, a shorter rest period resulted in recurrence of the lameness even though the horses were sound when put back into training. Careful clinical and radiographic examinations helped differentiate incomplete longitudinal fractures from lesions involving the carpus and proximal aspect of the suspensory ligament.     

IDENTIFICATION OF AN OSSICLE ASSOCIATED WITH THE PALMAR ASPECT OF THE CARPUS IN THE HORSE

An ossicle associated with the palmar aspect of the carpus is described in five horses. The size of the ossicle varied from 3 x 4 mm to approximately 12 x 10 mm. The ossicles were located at the junction of the proximal and distal rows of carpal bones, between the palmaromedial aspect of the fourth carpal bone and the ulnar carpal bone. In 3 horses they were bilateral, in one horse unilateral, and only one limb was examined in the remaining horse. In all horses it was an incidental finding and not regarded to be a pathologic entity.     

A new approach for perineural injection of the lateral palmar nerve in the horse

OBJECTIVE: To evaluate the accuracy of a new technique for perineural injection of the lateral palmar nerve and to determine frequency of inadvertent injection into the carpal synovial sheath with this technique. STUDY DESIGN: Prospective experimental study. ANIMALS: Thirty equine cadaver forelimbs. METHODS: Each of 3 clinicians injected 0.5 mL of a 1% aqueous solution of new methylene blue as a marker at the medial aspect of the accessory carpal bone of 10 limbs. Immediately after each injection, the lateral palmar nerve was identified by dissection of and inspected for proximity of dye, and the carpal synovial sheath was inspected for the presence of dye. RESULTS: New methylene blue solution was observed to surround the nerve (29 limbs) or to lie within 2 mm of it (1 limb). Dye was not found in the carpal synovial sheath of any specimen. CONCLUSIONS: Using this technique, perineural injection of the lateral palmar nerve can be consistently achieved, and the carpal synovial sheath is unlikely to be penetrated by the needle during the procedure. CLINICAL RELEVANCE: The technique described provides an accurate and simple method for perineural injection of the lateral palmar nerve proximal to the origin of its deep branch. This technique can be used to anesthetize the lateral palmar nerve for diagnosis of pain originating in the palmaroproximal aspect of the metacarpus without risk of inadvertently desensitizing structures within the carpal synovial sheath.     

Ultrasonographic examination of the caudal structures of the distal antebrachium in the horse

Evaluation of the caudal distal antebrachium using ultrasound is a very useful diagnostic procedure for identification of soft tissue abnormalities in flexor structures of the equine limb. In this article we describe how ultrasonographic imaging may be used to complement radiography of the carpus in evaluating horses that present with peri‐carpal swelling and/or lameness localised to the carpal region. Ultrasonographic examination assists with the identification or exclusion of significant injuries to muscular, tendonous and ligamentous structures within the distal antebrachium and enables practitioners to proceed with appropriate therapeutic and rehabilitation plans for the immediate benefit for their patients while also recognising pathology that could progress to cause long‐term, chronic lameness issues without aggressive and effective intervention.     

Arthroscopy of the antebrachiocarpal joint in dogs

A technique for arthroscopy of the antebrachiocarpal joint in dogs is described. Both antebrachiocarpal joints in 9 dog cadavers were examined arthroscopically and grossly to refine the technique and determine structures that could be seen. Two arthroscope portals were evaluated in each joint. The antebrachiocarpal synovium, ulnar carpal bone, distal portion of the ulna, medial and lateral collateral ligaments, accessory carpal bone, intercarpal ligament of the radial and ulnar carpal bone, distal portion of the radius, radial carpal bone, palmar process of the radial carpal bone, ligaments of the accessory carpal bone, palmar radiocarpal ligament, and palmar ulnocarpal ligament were visible and accessible to instruments. Arthroscopy was also performed in 5 client-owned dogs, allowing diagnosis of hyperextension injuries (n = 2), septic arthritis (2), and immune-mediated arthropathy (1). Arthroscopy of the antebrachiocarpal joint was found to be a useful adjunct to standard diagnostic modalities.     

The Arterial Supply of the Carpal Joint in the Bactrian Camel (Camelus Bactrianus)

The arterial supply of the six carpal joints was studied in Bactrian camels. The arterial branches supplying the carpal joints were the proximal medial dorsal, middle medial dorsal, distal medial dorsal, proximal lateral dorsal, distal lateral dorsal, proximal medial palmar, distal medial palmar, lateral palmar, proximal palmar and dorsal palmar carpi and the dorsal interosseous antebrachium branches. Some small unnamed branches supplied the diverticulum and the antebrachiocarpal joint capsule. All these arteries arose from the lateral and medial branches of the radial artery.     

Diffusion of contrast medium after four different techniques for analgesia of the proximal metacarpal region: an in vivo and in vitro study

Reasons for performing study: There is limited information on potential diffusion of local anaesthetic solution after various diagnostic analgesic techniques of the proximal metacarpal region. Objective: To document potential distribution of local anaesthetic solution following 4 techniques used for diagnostic analgesia of the proximal metacarpal region. Methods: Radiodense contrast medium was injected around the lateral palmar or medial and lateral palmar metacarpal nerves in 8 mature horses, using 4 different techniques. Radiographs were obtained 0, 10 and 20 min after injection and were analysed subjectively. A mixture of radiodense contrast medium and methylene blue was injected into 4 cadaver limbs; the location of the contrast medium and dye was determined by radiography and dissection. Results: Following perineural injection of the palmar metacarpal nerves, most of the contrast medium was distributed in an elongated pattern axial to the second and fourth metacarpal bones. The carpometacarpal joint was inadvertently penetrated in 4/8 limbs after injections of the palmar metacarpal nerves from medial and lateral approaches, and in 1/8 limbs when both injections were performed from the lateral approach. Following perineural injection of the lateral palmar nerve using a lateral approach, the contrast medium was diffusely distributed in all but one limb, in which the carpal sheath was inadvertently penetrated. In 5/8 limbs, following perineural injection of the lateral palmar nerve using a medial approach, the contrast medium diffused proximally to the distal third of the antebrachium. Conclusions and potential relevance: Inadvertent penetration of the carpometacarpal joint is common after perineural injection of the palmar metacarpal nerves, but less so if both palmar metacarpal nerves are injected using a lateral approach. Following injection of the lateral palmar nerve using a medial approach, the entire palmar aspect of the carpus may be desensitised.