Luxation and/or fracture of the first carpal bone in thoroughbred horses and its surgical resolution

A syndrome involving luxation and/or fracture of the first carpal bone is described. Affected horses have a grade 1-3 lameness, which responds to intra-articular anesthesia of the intercarpal joint. Medical treatment has not be successful in relieving lameness, and the treatment of choice is surgical removal of the first carpal bone.     

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.     

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.     

A case of dorso-medial luxation of the radial carpal bone in a dog

Luxation of the radial carpal bone is an uncommon injury in the dog and cat. Previous clinical cases have reported palmaro-medial luxation with injury to the short radial collateral ligament. In this study a case of dorsomedial luxation of the radial carpal bone in a 10-year-old female Gordon Setter is described. A closed reduction of the luxation was performed and a conservative treatment was carried out. Thirteen months after the reduction, the dog had a satisfactory limb function, despite the presence of degenerative joint disease of the carpus. A pathogenic hypothesis for this dorso-medial luxation of the radial carpal bone is proposed reproducing the luxation on canine cadavers.     

Luxation of the os carpi radiale in the dog—pathogenesis, symptoms, and treatment

During 13 years four cases of this rare, but typical luxation have been observed. After surgical reposition of the rotated radial carpal bone, it was held in place by an artificial collateral ligament inserted into the periosteum of the radius and the tendon of the m. ext. carpi obliquus . Within 2—4 months lameness disappeared and the range of articular movement was sufficient.     

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.     

Comminuted fracture of the accessory carpal bone removed via an arthroscopic-assisted arthrotomy

A 16-year-old American paint horse gelding was presented for evaluation of a left forelimb lameness grade III/V. Radiographs and computed tomography revealed a comminuted fracture of the accessory carpal bone involving the entire articulation with the distal radius and the proximal aspect of the articulation with the ulnar carpal bone. Multiple fragments were present in the palmar pouch of the antebrachiocarpal joint. An arthroscopic-assisted open approach was necessary to remove all fractured fragments. Subsequently the horse was re-admitted for lameness and was treated successfully with antibiotics and long-term supportive bandaging.     

Giant cell tumor of the accessory carpal bone in a dog

A 4-year-old Springer Spaniel was referred because of a 6-week history of progressive left forelimb lameness. A marked pain response was elicited by palpation over the left accessory carpal bone. Radiography revealed a lytic, markedly expansile lesion of the accessory carpal bone. The bone was excised, and pancarpal arthrodesis was performed. Histologic examination of the excised bone revealed giant cell tumor. At 14 months after surgery, the dog was using the limb normally. Radiography of the carpus revealed satisfactory progression of the arthrodesis, and thoracic radiographs were negative for metastases.     

Ulnocarpal arthrodesis in a cat

A nine-year-old cat was presented with non-weight-bearing lameness of the right forelimb subsequent to an old fracture of the antebrachium previously treated by external stabilisation. Radiography showed severe atrophic non-union of the distal third of the radius and carpal luxation. Ulnocarpal arthrodesis was performed using a uniplanar external fixator. Follow-up radiography showed that bone fusion was slow but without complication. After 16 weeks, the external fixator was removed, and a Robert-Jones bandage was applied for one month. From postoperative week 2 onwards, the animal progressively made use of the limb in a weight-bearing capacity. At the last examination, one year postoperative, no lameness was observed.     

Radial carpal bone fractures in 15 dogs

Between 1977 and 1992, 15 adult dogs were presented to the Universities of Bristol, Glasgow, Liverpool and London with fractures of the radial carpal bone which had occurred without a known episode of violent trauma. Eleven of the dogs were boxers and the other breeds affected were a Pharaoh hound, rottweiler, springer spaniel and a greyhound. The condition was bilateral in three cases. Eleven dogs were treated surgically by cast immobilisation (four cases), fragment removal (one case), lag screw fixation (three cases), pan-carpal arthrodesis (one case) and lag screw reduction followed by pan-carpal arthrodesis (two cases). The remaining four dogs were treated conservatively with rest and tactical use of non-steroidal anti-inflammatory drugs. Follow-up periods ranged from two months to 11 years. Varying degrees of lameness, which tended to be exacerbated by exercise, persisted in all cases. The radial carpal bone appears to have at least three separate centres of ossification which eventually fuse; their planes of fusion correspond approximately to the two main fracture lines. These areas of fusion could be weak points within the radial carpal bone.     

Clinical findings, diagnosis, prevalence and predisposing factors for lameness localised to the middle carpal joint in young Standardbred racehorses

REASONS FOR PERFORMING STUDY: Lameness related to the middle carpal joint (MCJ) occurs in up to 30% of young Standardbred horses in race training and the incidence increase with radiographic severity of third carpal bone (C3) sclerosis on DPr-DDIO (skyline) view of the carpus. Factors predisposing horses to carpal injury have not been well investigated. OBJECTIVES: To determine the importance of MCJ lameness as a cause of wastage in young Standardbred racehorses, stage of training at which it occurs and predisposing factors, and to describe clinical findings and diagnosis. METHODS: Standardbred horses (n = 114) entering their first year of race training were examined at approximately 3-month intervals over 12-18 months. For 87 of the horses, a training diary was available and these horses were trained at 3 different stables, each using a different exercise regime. At each examination, forelimb conformation, MCJ effusion, MCJ lameness and radiographic findings were graded, and training history and reasons for lost training days recorded. Nuclear scintigraphy and exploratory arthroscopy were performed on a limited selection of horses. Results for horses that developed MCJ lameness during the study period were compared statistically with results for horses that did not. RESULTS: Carpal lameness occurred in 28% of horses and was present in 56% with forelimb lameness. In most cases lameness was mild, bilateral and with little or no MCJ effusion and was attributed to subchondral bone pain associated with radiographic evidence of C3 sclerosis. Carpal lameness was the most common reason for >1 month's rest during the study period. It occurred at any stage of training but, in most cases, some speed training had begun. Of the variables studied, poor forelimb conformation and more intense speed training were predisposing factors. CONCLUSIONS AND POTENTIAL RELEVANCE: The information gained should assist in making recommendations regarding training young Standardbreds to reduce the incidence of MCJ lameness. However, further investigations to determine the optimal training regime are warranted.     

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.     

Sprain of the short radial collateral ligament in a racing greyhound

Severe carpal lameness in a racing greyhound due to a sprain of the straight part of the short radial collateral ligament is described. The dog subsequently developed an enthesiopathy at the origin of the ligament. Treatment was by kennel rest and the dog returned to successful racing.     

Sclerosis of the third carpal bone. A prospective study of its significance in a group of young standardbred trotters

To assess the significance of radiographic signs of sclerosis of the third carpal bone (C3) in young Standardbred trotters in relation to performance, lameness and bone turnover both carpi in 14 Standardbred trotters were radiographically and scintigraphically examined 6 times, from the beginning of speed training until the beginning of racing, between the mean ages of 20 and 42 months. At the end of the study 8 horses had raced in official qualifying races and 14 limbs in 11 horses had been diagnosed with carpal lameness. All horses but 2 developed sclerosis and all but one had increased bone turnover in the C3 area by scintigraphy. C3 sclerosis increased continuously over time and with increased performance. Carpal lameness was significantly associated with progression of sclerosis but in most cases sclerosis developed without concomitant signs of carpal lameness. No association between carpal lameness and increased scintigraphic uptake was found, but horses that had qualified for racing had significantly higher C3 to carpus ratio of radiopharmaceutical uptake. We conclude that there is a continuous increase in C3 radiographic sclerosis with time in young Standardbred trotters in professional training, but radiographic sclerosis appears to be of limited value as an indicator of clinical carpal disease or level of performance in Standardbred trotters.     

CARPAL ARTHRODESIS IN DOGS

SUMMARY Nine dogs, each with a severe carpal sprain injury, were treated by arthrodesis (2 bilateral). The same surgical technique with articular cartilage curettage, autologous bone grafting and compression plate fixation was used for each carpus. Initial treatment with external coaptation had been unsuccessful, but arthrodesis always resulted in resolution of the lameness. Complications included fracture of the compression plate (1 case) and loosening of the implants (2 cases).     

RADIOLOGIC ANATOMIC VARIATION OF THE CARPUS IN HORSES WITH CARPAL LAMENESS AND CONTROL HORSES

Our purpose was to describe the variation of the radiologic appearance of the carpus of horses of different breeds, discipline, and gender with lameness related to the carpus and control horses, with particular reference to the ulnar carpal bone. Two hundred and eighty‐six sets of carpal radiographs from 222 horses were analyzed. Breed, gender, discipline, and cause of lameness were recorded. Chi square tests were used to test for associations between radiologic findings and gender, breed and discipline, to test for associations between different radiologic findings, and to test for associations between radiologic findings and causes of lameness. Bonferroni correction was applied when necessary. The shape of the ulnar carpal bone and most of the anatomic variants, with the exception of the first carpal bone and a radiolucent area in the second carpal bone, were not breed or gender related. Radiolucent areas and associated fragments on the palmaromedial aspect of the ulnar carpal bone can be an incidental finding in horses from all disciplines.     

MAGNETIC RESONANCE IMAGING OF NORMAL CANINE CARPAL LIGAMENTS

Magnetic resonance imaging was conducted on previously frozen left carpi from six normal dogs using a 1.5 Tesla magnet in combination with a transmit/receive wrist coil. Three-millimeter thick T1-weighted spin-echo images and 1-mm thick T2*-weighted gradient-recalled 3-D images were obtained in dorsal and sagittal planes. Carpi were embedded, sectioned, and stained. Anatomic structures on the histologic sections were correlated with the MR images. All of the carpal ligaments plus the radioulnar articular disc and the palmar fibrocartilage were identified on MR images. The accessorio-quartile ligament, which had not been well described previously in dogs, was also identified. It originated on the accessory carpal bone and inserted on the fourth carpal bone. The T2*-weighted gradient echo imaging technique provided better images than T1-weighted technique, largely because thinner slices were possible (1 mm vs. 3 mm), resulting in less volume averaging of thin ligaments with surrounding structures. Although MRI is currently the imaging modality of choice to identify ligamentous injury in humans, further studies are needed to determine if abnormalities can be detected in canine carpal ligaments using MRI.     

The effect of intra-articular methylprednisolone acetate and exercise on equine carpal subchondral and cancellous bone microhardness

Dorsal carpal osteochondral injury is a major cause of lameness in horses undergoing high intensity training. Intra-articular corticosteroid treatment is used commonly to manage exercise-associated articular pain, but its use remains highly controversial in the equine athlete. This project, therefore, aimed to compare the mechanical properties of intra-articular MPA and diluent-treated middle carpal subchondral and cancellous bone in horses undergoing a short-term treadmill exercise programme. It was hypothesised that subchondral and cancellous bone mechanical properties are influenced by intra-articular administration of methylprednisolone acetate (MPA). Eight 2-year-old female horses had MPA or diluent administered into contralateral middle carpal joints at 14 day intervals, for a total of 4 treatments per horse. Horses underwent a standard treadmill exercise protocol until euthanasia (Day 70). Standard sites were located on the dorsal aspect of third, radial and intermediate carpal bones. Osteochondral samples from each test site were divided into subchondral bone and cancellous bone portions. These were dried, resin-embedded and gold-coated. Microhardness measurements were obtained at each test site. No significant effect of intra-articular treatment was detected. At each site, cancellous bone trabecular struts had an 18-19% higher microhardness value than the overlying subchondral bone. These findings indicate that intra-articular administration of MPA at this dose has no effect on subchondral or cancellous bone adaptation to short-term exercise and, therefore, on the propensity of carpal bones to injury. Further investigation into the calcified cartilage layer, effect of different corticosteroid preparations and diffusion of medication are required.     

Concurrent proximal suspensory desmopathy and injury of the proximal aspect of the accessory ligament of the deep digital flexor tendon in forelimbs or hindlimbs in 19 horses

Clinical features of proximal suspensory desmopathy (PSD) and concurrent injury of the proximal aspect of the accessory ligament of the deep digital flexor tendon (ALDDFT) have not been documented. The objectives were to describe clinical signs and diagnosis. This was a retrospective study. Patient details, lame limb(s), response to diagnostic analgesia, and radiographic and ultrasonographic findings were recorded. PSD and injury of the proximal aspect of the ALDDFT were identified in 19 horses, 14 with forelimb lameness (unilateral 5, bilateral 9) and 5 with hindlimb lameness (unilateral 2, bilateral 3). Localising clinical signs were seen in 7/31 lame limbs (subtle thickening in the region of the ALDDFT [n = 3], pain on palpation of the body of the suspensory ligament (SL) [n = 6], heat in the proximal metacarpal or metatarsal region [n = 2]). Forelimb lameness was abolished by perineural analgesia of the palmar metacarpal (subcarpal) nerves in 17/23 limbs. In the remaining limbs intra‐articular analgesia of the middle carpal joint (n = 2) or an ulnar nerve block (n = 4) were required to eliminate the lameness. Hindlimb lameness was abolished by perineural analgesia of the deep branch of the lateral plantar nerve (n = 2) or local infiltration of the proximal plantar aspect of the metatarsus (n = 3); a tibial nerve block resolved lameness in the remaining 3 limbs. Lesions of the SL and of the ALDDFT were characterised ultrasonographically by enlargement, heterogeneous echogenicity and loss of long linear echoes in longitudinal images. In 3 horses adhesions between the ALDDFT and the SL were identified post mortem. Close apposition of these structures seen ultrasonographically may indicate adhesion formation. It was concluded that the clinical features of PSD and concurrent injury of the ALDDFT are similar to those for PSD alone, highlighting the need for comprehensive and systematic ultrasonographic assessment.     

Modified Tenoscopic Method for Carpal Flexor Retinaculum Release in a Horse

Objective— To report the use of a proximolateral endoscopic portal with a distolateral instrument portal for carpal retinaculum release in a horse clinically affected with carpal canal syndrome. Study Design— Clinical report. Animals— A 4‐year‐old Thoroughbred female. Methods— Carpal canal syndrome secondary to traumatic suppurative tenosynovitis was treated by accessory carpal bone debridement and carpal retinaculum release using a tenoscopic approach to the carpal flexor synovial sheath through a proximolateral endoscope portal and a distolateral instrument portal. Results— Resolution of carpal sheath effusion and lameness occurred allowing racing 14 months later. Use of a distolateral instrument portal was not associated with complications or iatrogenic damage to neurovascular structures and reduced endoscope and instrument interference and offered easier access to the distal aspect of the carpal sheath. Conclusions— Carpal retinaculum release may be safely accomplished with a distolateral instrument portal when access to the distal aspect of the carpal sheath is needed. Clinical Relevance— The distolateral instrument portal described may be a useful alternative to a proximolateral portal when distal carpal sheath instrument access is necessary or advantageous.