Radiographic and clinical features of carpal varus associated with chronic sprain of the lateral collateral ligament complex in 10 dogs.

Lameness associated with carpal varus deformity was recognised in 10 dogs, eight of which were Dobermann Pinschers. The dogs had a mean age of seven years and nine months. Carpal varus was usually bilateral with concurrent carpal hyperflexion and pronation. Carpal varus was present prior to the onset of lameness in four cases. With stress radiography the median angle of varus deviation in all carpi was 14.6 degrees , and an increase in the size of the ulnar /ulnar carpal bone joint space was seen in six of the seven dogs. Radiographic changes included: enthesophyte formation at the proximolateral aspect of metacarpal V, periarticular soft tissue swelling, especially lateral, bone proliferation at the carpometacarpal joint I and enthesophyte formation at metacarpophalangeal joint V. Four dogs were admitted for problems other than carpal varus and lameness was not treated. Five dogs were treated with nonsteroidal anti-inflammatory drugs, but lameness was not completely resolved and became exacerbated with exercise. One dog was successfully treated by pancarpal arthrodesis.     

Subluxation/luxation of the second carpal bone in two racing greyhounds and a Staffordshire bull terrier

Subluxation of the second carpal bone (C2) in two racing greyhounds, and luxation associated with other carpal injuries in a Staffordshire bull terrier, were diagnosed as causes of thoracic limb lameness. The clinical signs of subluxation were subtle, with local soft tissue swelling and a pain reaction on digital pressure over the dorsal aspect of C2. In contrast, the dog with a complete luxation was very lame, having marked soft tissue swelling with carpal hyperextension and valgus. Diagnosis was made by radiography. Subluxation of C2 was seen as a small, dorsally displaced opacity between the proximal and distal rows of carpal bones on the mediolateral view and, on the oblique view taken in only one case, as a marked dorsal displacement of one-third of the proximal joint surface of C2. In the case of luxation, C2 appeared on the mediolateral view lying dorsal to the radial carpal bone. There was also fracture of C4. Both greyhounds were treated by internal fixation and returned to racing. The Staffordshire bull terrier was treated by pancarpal arthrodesis with a successful outcome.     

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.     

Pulsed Carbon Dioxide Laser for Cartilage Vaporization and Subchondral Bone Perforation in Horses Part I: Technique and Clinical Results

A carbon dioxide laser, used in a rapidly pulsed mode, was evaluated for intra-articular use in horses. Under arthroscopic guidance, a lensed 5 mm laser probe attached directly to a hand-held carbon dioxide laser was inserted into one intercarpal joint of eight horses. In four horses, a cartilage crater 1 cm in diameter was created to the level of the subchondral bone of the articular surface of the third carpal bone. In four horses, the laser was directed perpendicular to the articular surface of the third carpal bone and activated to penetrate the cartilage and subchondral bone. The intercarpal joint of the opposite carpus in each horse was subjected to arthroscopic examination and insertion of the laser probe for an equivalent time. The laser was not activated and these joints served as sham operated controls. The horses were evaluated clinically for 8 weeks, then euthanatized, and the joints were examined radiographically, grossly, and histologically. Pulsed carbon dioxide laser vaporized cartilage readily but penetrated bone poorly. Cartilage vaporization resulted in no greater swelling, heat, pain on flexion, lameness, or synovial fluid reaction than the sham procedure. Laser drilling resulted in a shallow, charred hole with a tenacious carbon residue, and in combination with the thermal damage to deeper bone, resulted in increased swelling, mild lameness and a low-grade, but persistent synovitis. The carbon dioxide laser is a useful intra-articular instrument for removal of cartilage and has potential application in inaccessible regions of diarthrodial joints. It does not penetrate bone sufficiently to have application in subchondral drilling.     

Accuracy of Arthroscopic Identification of Equine Carpal Lesions

The equine carpal joint was used to evaluate arthroscopic diagnosis of lesions created in joints obtained from horses euthanized for reasons other than lameness. Full-thickness articular defects were made in 13 sites within the antebrachiocarpal joint and middle carpal joint approximating those found in diseased carpal joints. Arthroscopic evaluation of the lesions included location, depth, and size of the defects. The joints were subsequently examined grossly. Results showed that, when compared to gross evaluation, arthroscopy is capable of accurately identifying subtle changes in articular cartilage and bone. A statistically significant increase in error rate was found for lesions at the medial aspect of the proximal radial carpal bone. Other sites with limited arthroscopic access were the proximal ulnar carpal bone, the proximal fourth carpal bone, and the distal intermediate carpal bone. The accuracy of arthroscopic identification of lesions improved significantly during the study as experience with the technique was gained.     

Computed tomographic documentation of a comminuted fourth carpal bone fracture associated with carpal instability treated by partial carpal arthrodesis in an Arabian filly

OBJECTIVE: To report treatment of a unilateral comminuted fourth carpal bone (C4) fracture associated with carpal instability by partial carpal arthrodesis (PCA) of the middle carpal joint (MCJ) and carpometacarpal joint (CMCJ). STUDY DESIGN: Case Report. ANIMALS: An 8-month-old Arabian filly. METHODS: A C4 slab fracture was diagnosed radiographically; however, fracture comminution was conclusively diagnosed after computed tomographic (CT) imaging. PCA of the MCJ and CMCJ was performed with 2 narrow dynamic compression plates. RESULTS: PCA provided appropriate carpal stability and correct limb alignment immediately after surgery. Complete bony fusion with substantial carpal flexion and no lameness at walk or light trot was observed 8 months after surgery. CONCLUSIONS: Carpal CT was successfully used to define fracture configuration after standard radiographic examination failed to delineate comminution. PCA was selected because of joint instability and lateral carpal collapse of MCJ and CMCJ and can be successfully used to treat comminuted C4 slab fractures associated with carpal instability. Moderate MCJ osteoarthritis without radiocarpal joint involvement allows pain-free, substantial carpal flexion and thus, return to low-level pleasure riding may be possible. CLINICAL RELEVANCE: CT imaging may more adequately characterize traumatic carpal bone injury, particularly, when carpal bone fracture configuration cannot be determined on standard radiographs. Early PCA of the MCJ and CMCJ is an useful alternative to treat comminuted C4 slab fractures that cannot be reconstructed.     

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.     

Unusual Polydactylism in a Foal: A Case Report

A 2 month old quarter horse colt had multiple skeletal abnormalities of the left fore limb, including two supernumerary metacarpal bones, two supernumerary carpal bones, abnormal carpal bone development, and a valgus deformity originating at the carpal joint. The largest supernumerary metacarpal bone was removed completely, a portion of the smaller supernumerary metacarpal bone was removed, and the leg was placed in a tube cast. Surgical treatment improved the clinical appearance and prevented further injury to the limb. The carpal joint width remained increased but the carpal valgus deformity partially responded to hemicircumferential periosteal transection. The foal was sound 2 1/2 years after surgery.     

Carpal arthrodesis using a minimally invasive approach and locking compression plates: Three cases

Three horses with carpal instability due to comminuted second carpal bone fractures (Cases 1 and 3), fracture of the head of the second metacarpal bone (Case 1) or comminuted fractures of the fourth carpal bone, ulnar and intermediate carpal bones (Case 2) were treated by minimally invasive approach for partial (Cases 1 and 3) or pancarpal (Case 2) joint arthrodesis, using locking compression plates. The joint cartilage was removed by either an arthroscopic approach (middle carpal joint and antebrachiocarpal joint) or a percutaneous drilling technique (carpometacarpal joint). Two or 3 locking compression plates were contoured to the dorsolateral, dorsomedial and dorsoaxial aspects of the carpal joints using a custom‐made tunnelling tool and a minimally invasive tunnelling technique, and the screws were positioned through stab incisions. All cases recovered well, were lame free at the walk, were able to trot and gallop and could be used for leisure and pasture activities (partial carpal arthrodesis) and breeding (pancarpal arthrodesis). Post‐operative x‐rays showed progressive joint fusion after 12 months (Case 1), 5 months (Case 2) and 10 months (Case 3). Case 2 with a pancarpal arthrodesis showed a mechanical lameness at the walk due to the inability to flex the carpus. Carpal flexion after carpometacarpal and middle carpal arthrodesis in Case 1 was calculated to be 42.6° and 44° in Case 3.     

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.     

Antebrachial metacarpal arthrodesis for fusion of deranged carpal joints in two dogs

Congenital malformation of the carpal joint in a young dog resulted in a progressive lameness. Traumatic disruption of the carpus in another dog resulted in carpal bone necrosis, infection, and chronic instability. Radial metacarpal arthrodesis was performed in both dogs. The diseased carpal bones were excised, sparing the accessory carpal bone in both dogs. Radial metacarpal arthrodeses were then performed, using bone plate fixation. In the dog with the malformed limb, the gait had improved, but intermittent lameness was still present 8 months later because of an associated malarticulation of the cubital joint. The dog with the traumatized carpus had little or no lameness associated with normal activity for 32 months.     

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.     

Chondrosarcoma in the radius of a horse

An aged Thoroughbred stallion was examined because of progressive lameness, carpal swelling, and weight loss. Radiography revealed a destructive lesion in the caudomedial, distal portion of the radius. Chondrosarcoma was diagnosed by tumor-core biopsy. Gross and histologic evaluation of the neoplasm after necropsy revealed a locally invasive chondrosarcoma at the distal end of the radius that infiltrated the radiocarpal joint capsule and invaded the carpal bones. The malignant nature of this tumor was evident by its invasiveness and histologic features of cell pleomorphism and presence of mitotic figures.     

Radial carpal bone fracture in dogs

In a retrospective study, 11 radial carpal bone (RCB) fractures in nine dogs were studied. Chronic lameness was reported in all dogs. Reduced range of motion and soft-tissue swelling of the carpal joints were clinical signs seen most frequently. Three common fracture patterns were identified: oblique fracture with a large medial fragment, sagittal fracture with a small medial fragment, and comminuted fracture. Radial carpal bone sclerosis and carpal osteoarthritis were identified in all dogs. Pancarpal arthrodesis was used to manage 55% of the RCB fractures in this report. Although RCB fracture is not associated with obvious trauma, the fracture mechanism is unknown.     

Bilateral angular carpal deformity in a dog with craniomandibular osteopathy

A four-month-old West Highland White Terrier was presented to the Small Animal Teaching Hospital at the University of Liverpool with the complaint of a bilateral angular carpal deformity. A 20° valgus deformity was present in both thoracic limbs, centred on the distal radial physes. Both distal ulnas were grossly thickened and there was concomitant thickening of the rostral mandible and calvarium. The dog exhibited signs of resentment on palpation of the mandible and signs of pain were elicited on flexion and extension of both elbow joints. No signs of pain were evident on palpation of the ulnas or calvarium. Radiographic images of both ulnas showed marked amorphous periosteal new bone formation. The distal ulnar physes were closed centrally and both elbow joints had humeroulnar subluxation. Radiographic changes to the calvarium and mandibular rami were consistent with a diagnosis of craniomandibular osteopathy. A bilateral ulna ostectomy was performed to correct the angular limb deformity and elbow subluxations. Histology of the ostectomised pieces showed changes consistent with craniomandibular osteopathy.     

A RADIOGRAPHIC INVESTIGATION OF THIRD CARPAL BONE INJURY IN 42 RACING THOROUGHBREDS

A retrospective study of carpal radiographs from 42 racing thoroughbreds with carpal lameness was performed. Radiographs from 50 carpal examinations were available for review. The radiographic findings pertaining to the third carpal bone were described. Fractures and/or sclerosis occurred almost exclusively within the radial fossa. The occurrence of sclerosis without fracture in 20 of the 50 carpal examinations was higher than anticipated, occurring in both the right and left third carpal bone with equal frequency. The right third carpal bone was more frequently fractured and more severely affected than the left. The sclerotic changes seen in the radial fossa of the third carpal bone may be stress-induced, possibly preceding more serious changes in the joint such as cartilage damage or gross fracture. Earlier recognition of sclerosis of the third carpal bone may help prevent more serious changes from occurring.     

Radiographic and scintigraphic evaluation of the third carpal bone of control horses and horses with carpal lameness

We compared the radiographic and scintigraphic findings in the third carpal bone of horses performing different work disciplines and investigated their relationship with lameness. Horses had undergone carpal radiography including acquisition of a dorsoproximal-dorsodistal oblique (DPr-DDiO) image of the distal row of carpal bones and/or scintigraphic examination of the carpi. Cause of lameness, breed, age, and work discipline were recorded. Increased opacity in the third carpal bone was graded, ratio of radiopharmaceutical uptake calculated objectively, and increased radiopharmaceutical uptake graded subjectively. Relationships between radiographic, scintigraphic, and clinical findings were assessed statistically. Increased opacity in the third carpal bone (P = 0.003) and ratio of radiopharmaceutical uptake (P = 0.015) were associated with the work discipline. Increased opacity in the third carpal bone was associated with both increased radiopharmaceutical uptake grade (P = 0.002; rs = 0.59) and ratio of radiopharmaceutical uptake (P = 0.013; rs = 0.46). Increased radiopharmaceutical uptake and increased opacity in the third carpal bone were not always observed concurrently. Lameness related to the middle carpal joint was associated with increased opacity (P < 0.001), ratio of radiopharmaceutical uptake (P = 0.037), and increased radiopharmaceutical uptake grade (P < 0.001). Radiographic and scintigraphic abnormalities were observed in horses performing all disciplines, indicating that high-speed exercise may not be the only factor determining the development of osseous disease in the third carpal bone. Both increased opacity and increased radiopharmaceutical uptake were more likely to be seen in horses with lameness related to the middle carpal joint than in horses with other sources of pain.     

Craniomandibular osteopathy with a unique neurological manifestation in a young Akita

This report describes a 4 mo old intact male Akita that presented for evaluation of a life-long history of facial swelling and failure to thrive. Physical examination revealed an enlarged cranium with prominent bony swellings on the maxillary bone, excessive laxity and crepitus involving multiple joints, and proprioceptive deficits. Radiographs demonstrated multiple osseous abnormalities including endosteal thickening of the femurs and ilium. Necropsy revealed gross compression of the cerebellum and brainstem. Physical exam findings, radiographic abnormalities, and histopathology of multiple bony lesions were all consistent with craniomandibular osteopathy. In this unique case of craniomandibular osteopathy, the dog was affected with severe bony proliferations leading to generalized hyperostotic lesions and brainstem compression resulting in neurologic deficits.     

Fate and effect of autogenous osteochondral fragments implanted in the middle carpal joint of horses.

Four autogenous osteochondral fragments removed from the lateral trochlear ridge of the talus were arthroscopically placed as loose bodies in a randomly selected middle carpal joint in each of 10 horses. The contralateral middle carpal joint, subjected to a sham procedure, served as control. Postoperative treatment was consistent with that for clinical arthroscopic patients. Lameness evaluation, radiographic examination, carpal circumference measurement, and synovial fluid analysis were performed before and at scheduled intervals after surgery. After a 2-month confinement, horses were subjected to an increasing level of exercise. Horses were euthanatized at intervals through 6 months. Gross and microscopic evaluations were performed on remaining fragments, articular cartilage, and synovial membrane of each middle carpal joint. Increased joint circumference, effusion, lameness, and degenerative joint disease distinguished implanted from control joints over the 6-month period. Implanted joints were characterized by grooved, excoriated cartilage surfaces, and synovium that was thick, erythematous, and irregular. At 4 weeks, implants were found to have adhered to synovium at their subchondral bone surface. The bone within fragments was undergoing necrosis, while cartilage was preserved. At 8 weeks, fragments were radiographically inapparent, grossly evident as pale plaques on the synovial surface, and composed of dense fibrous connective tissue. Synovial membrane specimens from implanted joints had inflammatory change characterized by mononuclear cell infiltration 2 months after implantation. Physical damage was apparent within articular cartilage of implanted joints at 2 months, and was significant (P less than 0.05) at 6 months after surgery. Chondrocyte degenerative change was significant (P less than 0.05) at 6 months after surgery. Focal reduction in safranin-O uptake was observed in cartilage layers adjacent to physical defects. Osteochondral loose bodies of the size implanted in the middle carpal joint of horses in this study were resorbed by the synovium within 2 months. Synovitis and significant articular cartilage damage were associated with the implanted fragments. Regardless of origin, free osteochondral fragments within the middle carpal joint should be removed, and methods to prevent residual postoperative debris should be implemented to reduce potential for articular pathologic change.