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.     

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.     

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.     

Accessory Carpal Bone Fractures in the Racing Greyhound: Classification and Pathology

Fractures of the accessory carpal bone in 35 racing Greyhounds were classified into five types. Type I fractures (27 fractures) involved the distal articular surface of the accessory carpal bone, type II (6 fractures) were of the proximal articular margin, type III (1 fracture) were at the origin of the accessorometacarpal ligaments, type IV (6 fractures) were avulsion fractures at the tendon of insertion of the flexor carpi ulnaris muscle, and type V (3 fractures) were comminuted fractures.     

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.     

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.     

Tears of the palmar superficial fascia in five racing greyhounds and a Labrador retriever

Tears of the palmar superficial fascia over the palmar extremity of the accessory carpal bone were identified as the cause of lameness in five racing greyhounds and as a coincidental finding in a Labrador retriever with an avulsion of the insertion of the flexor carpi ulnaris tendon. The lameness in the greyhounds was mild and transient, although racing performance was affected. The Labrador retriever was severely lame. In all cases there was a marked soft tissue swelling and a palpable defect in the superficial fascia. One case was managed conservatively and surgical repair was performed in the remaining five cases. The greyhounds returned to successful racing and the Labrador retriever made a complete recovery.     

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)     

Macroscopic study of the functional significance of the forearm muscles in the giant panda

The extensor and flexor group muscles and their related muscles were functional-morphologically observed in the dead body of the giant panda to clarify the action of the forearm and the palm in the manipulation of the species. The Musculus flexor carpi ulnaris had two developed heads, however, we can conclude that the contraction of this muscle slightly changes the angle of the accessory carpal bone to the ulna. The data pointed out that the accessory carpal bone acts as a supporting post, when the giant panda seizes the object. The M. abductor digiti I longus possessed the well-developed origin in both ulna and radius. These findings suggest that this muscle may function as a supinator of the forearm. We also suggest that the well-developed M. pronator quadratus and M. pronator teres, and the proximal part of the M. abductor digiti I longus and the M. supinator may efficiently contribute to the pronator-spinator action of the forearm, when the giant panda brings the food to its mouth using the manipulation system equipped in the palm region.     

Flexural deformity of the carpus in puppies

A flexural deformity affecting one or both forelimbs identified in 21 puppies of six to 12 weeks of age closely resembled a condition which has long been known in foals and farm animals at birth or shortly afterwards. In the puppies the characteristic feature was carpal hyperflexion which was associated with tautness of the tendons of the flexor carpi ulnaris muscle. The majority recovered spontaneously with conservative management but in two puppies it was necessary to section the shortened tendons to enable a normal limb posture to be regained. The fact that there was a preponderance of dobermann pinschers (17 out of 21) in the group opens speculation about an hereditary factor being involved, but further study is needed before such a correlation can be reached.     

Diagnosis and treatment of carpometacarpal desmopathy in a horse

A 9‐year‐old Warmblood gelding underwent magnetic resonance (MR) imaging of the carpal and proximal metacarpal regions for evaluation of prolonged right forelimb lameness. Magnetic resonance findings were indicative of desmopathy of the right lateral carpometacarpal ligament and the interosseous ligament between the third and fourth metacarpal bones. Based on the MR findings and lack of response to conservative therapy, surgery using a drilling technique was performed to facilitate fusion of the right carpometacarpal joint. After surgery and a 6‐month rest and rehabilitation programme, the horse returned to soundness. This case report describes a unique combination of lateral carpal/proximal metacarpal soft tissue injuries that resulted in prolonged lameness and were treated with facilitated arthrodesis of the carpometacarpal joint. These soft tissue injuries should be considered as a differential diagnosis in horses with lameness localised to the proximal metacarpal/distal carpal region.     

Endoscopy of the Calcaneal Bursa in Horses

Objective —To describe endoscopic approaches to the calcaneal bursa and clinical findings in 2 horses with calcaneal bursitis.
Study Design —Cadaver evaluations and retrospective case reports.
Animals —12 cadavers and 2 adult horses.
Methods —Cadaver specimens of the calcaneal bursa were evaluated with a rigid arthroscope and gross dissection to determine the endoscopic appearance of anatomic structures located within the bursa. The site(s) for placement of the arthroscope and instrument(s) was determined based on cadaver dissection and endoscopic examination.
Results —Placement of the arthroscope 1 cm dorsal to the superficial digital flexor tendon (SDFT) and 1 cm distal to the medial or lateral aspect of the SDFT retinaculum allowed consistent examination of the tuber calcis, proximal aspect of the long plantar ligament, calcaneal tendon of the gastrocnemius muscle inserting on the tuber calcis, SDFT and the proximal and distal extent of the bursa. Lesions observed and treated with use of endoscopy included local bone necrosis of the proximoplantar aspect of the tuber calcis and damage of the origin of the long plantar ligament in one horse. Mild disruption of the superficial digital flexor tendon and long plantar ligament were observed and debrided in another horse.
Conclusions —Endoscopic exploration of the calcaneal bursa is clinically feasible to treat infectious and noninfectious bursitis and to help identify the cause(s) of undiagnosed bursitis or lameness associated with the calcaneus, superficial digital flexor tendon, tendon of the gastrocnemius muscle, and the long plantar ligament.
Clinical Relevance —An endoscopic approach to the calcaneal bursa is recommended whenever possible to decrease complications associated with surgery in this region and improve the diagnosis of infectious and non-infectious calcaneal bursitis.     

Use of Buccal Mucosal Flaps for the Correction of Congenital Soft Palate Defects in Three Dogs

Objective —To present an alternative surgical technique for the repair of soft palate defects in dogs.
Animal Population —Three Foxhound cross dogs.
Methods —Bilateral buccal mucosal flaps, based at the palatoglossal arches, were raised. One flap was rotated so that the mucosal side created the floor of the nasopharynx. The second flap was rotated so that the mucosal side formed the roof of the oropharynx. The mucosa of the remnant of the soft palate and the pharyngeal walls was incised and the flaps sutured to these free mucosal edges. The caudal ends of the two flaps were sutured to each other.
Results —Complete closure of the soft palate defect was obtained in all three dogs. The dogs were monitored for between 1.5 and 3 years postoperatively, and no long-term problems were encountered.
Conclusions —This surgical technique resulted in an excellent functional separation of the oropharynx and nasopharynx and allowed reconstruction of a large bilateral soft palate defect.
Clinical Relevance —By using the buccal mucosal flaps, as described in this report, a tension-free closure of large soft palate defects can be obtained, thereby eliminating a major cause of failure of this type of reconstructive surgery.     

Concurrent use of a medial saphenous fasciocutaneous free tissue flap and external skeletal fixation for treatment of a distal antebrachial injury in a dog

OBJECTIVE: To report the surgical management of a traumatic distal antebrachial wound using a medial saphenous fasciocutaneous free tissue flap and a type I external skeletal fixator (ESF). STUDY DESIGN: Case report. ANIMALS: A 7-year-old spayed, female Labrador retriever. RESULT: Wound coverage and pancarpal arthrodesis were accomplished during a single anesthetic episode using a medial saphenous fasciocutaneous free tissue flap and type I ESF. A second surgical procedure was performed to expedite healing of part of the original wound that was initially left to heal by second intention. CONCLUSIONS: Free tissue transfer can be used in combination with an ESF for repair of distal antebrachial wounds, allowing orthopedic repair and soft tissue coverage in a single anesthetic episode. CLINICAL RELEVANCE: Concurrent use of free tissue transfer and carpal arthrodesis with an ESF could be used for repair of complex antebrachial wounds without need for multiple procedures, extended hospitalization, and increased cost.     

Arthroscopic Approaches and Intraarticular Anatomy of the Equine Elbow

Periarticular anatomy and techniques for arthroscopic access to the equine elbow were studied in six joints from cadavers. Caudomedial and craniolateral approaches were evaluated subsequently in 11 anesthetized horses. The caudomedial approach was made between the flexor carpi radialis and flexor carpi ulnaris muscle bellies. Most of the caudal articular surfaces of the humeral condyles, the caudal perimeter of the radius, and the trochlear notch and portions of the anconeal process of the ulna could be identified. The voluminous caudal joint capsule cul-de-sac proximal to the anconeal process was readily entered. A 70 degree arthroscope allowed examination of more of the joint recesses and articular surfaces of the olecranon fossa than a 25 degree arthroscope. A second portal for intraarticular instrument manipulation was made caudal and slightly proximal to the arthroscope entry. Entry more proximal than the level of the radiohumeral articulation carried significant risk of damage to the ulnar nerve and collateral ulnar artery and vein. For examination of the cranial regions of the elbow, a craniolateral portal was established cranial to the lateral collateral ligament. An instrument portal was made through the muscle bellies of the extensor carpi radialis or common digital extensor muscles. The cranial articular surfaces of the humeral condyles were readily exposed by extension of the elbow. The weight-bearing articular surface of the radius could not be seen. Eight horses were euthanatized without recovery from anesthesia and the elbows were dissected for examination. Three horses were allowed to recover from anesthesia and were euthanatized on days 3, 30, and 60.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in Third Carpal Bone Articular Cartilage After Synovectomy in Normal and Inflamed Joints

Objective —To determine if arthroscopic synovectomy in normal and inflamed joints had temporal or site-related effects on articular cartilage.
Study Design —Alterations in equine third carpal bone articular cartilage were studied at two time periods: groups 1 and 2 (6 weeks) and groups 3 and 4 (2 weeks) after synovectomy in normal (groups 2 and 4) and inflamed carpi (groups 1 and 3).
Animal Population —16 carpi from eight horses.
Methods —Biochemical and biomechanical properties of dorsal and palmar articular cartilage were determined by radiolabeling, proteoglycan (PG) extraction, chromatography, electrophoresis, and indentation testing.
Results —Synovectomy in inflamed joints produced the greatest concentration of newly synthesized PG in articular cartilage by 2 weeks. Synovectomy in normal joints produced significantly greater newly synthesized PG in articular cartilage by 6 weeks. Endogenous PG was only significantly greater in inflamed joints after 6 weeks. Dorsal sites had greater newly synthesized and endogenous PG in some groups. Chromatographic profiles of newly synthesized PG demonstrated early and late PG peaks. Electrophoresis of late PG peak showed a toluidine blue-positive band that comigrated with human A1D1 PG monomer in the two groups with the most newly synthesized PG. This band was reactive with monoclonal antibody 1C6 specific for the hyaluronic acid-binding region of aggrecan. For the material properties evaluated, only Poisson's ratio was significantly decreased between groups as a function of time (6 weeks < 2 weeks), and this was most pronounced in the thicker dorsal sites.
Conclusions —Synovectomy in inflamed joints produced site-specific, significantly greater responses in articular cartilage as compared with synovectomy in normal joints.
Clinical Relevance —Synovectomy may not be beneficial to the articular cartilage in inflamed joints.     

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.     

Identification and categorization of the vascular patterns to muscles of the thoracic limb, thorax, and neck of dogs.

Vascular patterns to thoracic limbs, thorax, and neck muscles were studied in 10 dogs (20 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify vascular pedicles. Size and location of pedicles were generally consistent, and any variations would not interfere with most muscle transfers. The cutaneous trunci, latissimus dorsi, sternothyroideus, sternohyoideus, deep pectoral, anconeus, ulnaris lateralis, and ulnar head of flexor carpi ulnaris muscles were identified as suitable for transfer. The cranial trapezius, caudal omotransversarius, cleidobrachialis, and caudal sternocephalicus muscles also had potential for use. Other muscles, because of inaccessibility or unfavorable vascular pattern, were not suitable candidates for transfer.     

Fragmented Coronoid Process and Incomplete Ossification of the Humeral Condyle in a Rottweiler

Objective —To describe incomplete ossification of the humeral condyle and fragmentation of the medial coronoid process in a Rottweiler.
Study Design —Clinical report.
Animal Population —A 4-year-old sexually intact male Rottweiler.
Methods —Physical examination, radiography, and computed tomography of both elbow joints were performed initially. Drill holes were made across the humeral condyle to promote ossification. Radiography and computed tomography were repeated 14 weeks later. Radiography was repeated 15 months later. A mild, intermittent lameness remained.
Results —Preoperatively a radiolucent line was present across the right humeral condyle. This radiolucent line remained unchanged 14 weeks after drill holes were made across the condyle.
Conclusions —Incomplete ossification of the humeral condyle is present in Rottweilers.
Clinical Relevance —Incomplete ossification of the humeral condyle is present in Rottweilers and may coexist with fragmentation of the medial coronoid process in that breed. The radiographic diagnosis may be difficult because precise positioning is required to see the area of incomplete ossification. Computed tomography may be required to confirm the presence of incomplete ossification of the humeral condyle. Drilling holes across the humeral condyle does not appear to lead to union of the area of incomplete ossification.     

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.