Canine Carpal Injuries: From Fractures to Hyperextension Injuries.

The canine and feline carpus is a complex arrangement of bones, ligaments, and joint spaces that functions as a ginglymus joint to provide carpal flexion and extension. Given the demanding biomechanical demands on the carpus during weight bearing, a variety of region-specific pathology, often secondary to trauma, are reported. This review details carpal anatomy, biomechanical understandings, and current evidence surrounding carpal pathology and its management. Partial carpal arthrodesis and pancarpal arthrodesis outcomes are reviewed in detail.

Management of feline carpal injuries: What are the options and when is arthrodesis indicated?

PRACTICAL RELEVANCE: Feline carpal injuries are usually caused by falls from a height that result in hyperextension injury or antebrachiocarpal luxation or subluxation. Isolated ligamentous damage or fracture of the carpus is unusual; it is more common to have a combination of both in the cat. These injuries can be debilitating since cats climb and jump from great heights, and have a greater range of antebrachial pronation and supination than dogs. ANATOMY: There are differences in the anatomy of the feline and canine carpus. In particular, cats only have a single short radial collateral ligament, also known as the medial collateral ligament. This means that, in the cat, antebrachiocarpal subluxation is possible with rupture of the dorsal joint capsule and short radial collateral ligament alone. CLINICAL CHALLENGES: Many feline carpal injuries can be treated without performing pancarpal arthrodesis. However, determining which ligaments and joint levels are affected requires careful examination and often stress radiography. When pancarpal arthrodesis is performed in the cat, it has been reported to reduce the height of jumping and to increase reluctance to climb. This is speculated to be due to reduced pronation and supination movement of the carpus. EVIDENCE BASE: The current evidence base for management of feline carpal injuries is grade III or IV, with most of the studies being retrospective case series involving cadaveric dissection or direct extrapolation from published information about the dog. There are few guidelines regarding the optimal treatment options for carpal injuries in the cat.

Sampling strategies for assessing lameness, injuries, and body condition score on dairy farms.

Our objective was to evaluate how sampling strategies (i.e., how many cows to sample and which animals to include) used in 4 dairy cattle welfare assessment programs affect the classification of dairy farms relative to thresholds of acceptability for animal-based measures. We predicted that classification performance would improve when more cows were sampled and when selecting from all lactating cows versus when some pens were excluded. On 38 freestall farms, we assessed all 12,375 cows for lameness, injuries on the tarsal (hock) and carpal joints, and body condition score and calculated the farm-level prevalence for each measure. Based on approaches used in the industry, we evaluated 6 sampling strategies generated using formulas with precision (d) of 15, 10, or 5% applied to either a single high-producing pen or all lactating cows; an additional sample was included with d = 10% applied to the entire herd, selecting lactating cows in proportion to their representation in the herd. For each sampling strategy, cow records were selected randomly (in 10,000 replicates) to calculate prevalence. The strategy of assessing all cows in the high-producing pen was also compared. Farms were classified as meeting (below) or failing to meet (above) thresholds of ≤15% moderate lameness; ≤20% moderate carpal or hock injuries; <10, <5, and ≤1% severe lameness; or injuries on the carpus or hock; and <5, <3, <1, or 0% thin cows. For each measure and threshold, we calculated pooled percent agreement, kappa, sensitivity, specificity, and positive and negative predictive value for each sampling strategy using true prevalence as the gold standard for herd classification. Across measures and thresholds, classification performance increased with the number of cows sampled [i.e., when narrower precision values (d = 5 vs. 10 vs. 15%) were used in the sample size calculation]. Because narrower precision values can dramatically increase sample size, assessment programs may need to consider both feasibility and the degree of misclassification they will accept. Applying the formula directly to lactating cows performed better than applying it to the entire herd and then selecting lactating cows in proportion to their representation in the herd. Farm classifications were similar whether cows in the hospital pen were included or excluded from the sample. Selecting all cows from the high-producing pen resulted in classifications similar to when including all lactating cows, suggesting that assessing cows from the high-producing pen may serve as an acceptable proxy for all lactating cows on the farm.

Return to racing after surgical management of third carpal bone slab fractures in thoroughbred and standardbred racehorses.

OBJECTIVE: To determine the prognosis for racing of horses surgically treated for slab fractures of the third carpal bone (C3). STUDY DESIGN: Retrospective case study. ANIMALS: Horses (n = 125) surgically treated for C3 slab fractures. METHODS: Medical records of horses surgically treated for dorsal or sagittal C3 fractures were reviewed for age, sex, breed, limb, fracture type, degree of cartilage damage, and surgical treatment. Radiographs were evaluated to determine fracture depth, width, and displacement. Osteophytes, C3 lysis, and fragmentation were scored. Racing performance was obtained from online databases. Univariable and multivariable analyses were used to determine associations between independent variables and outcomes. RESULTS: Fifty-four (43%) horses raced postoperatively. Among thoroughbreds, 35% (30/86) with dorsal fractures and 63% (17/27) with sagittal fractures raced postoperatively. Among standardbreds, 77% (10/13) with dorsal fractures and 0% (0/2) with sagittal fractures raced postoperatively. Fracture displacement, C3 lysis, and cartilage damage affected the likelihood of racing postoperatively. Placement of 3.5-mm screws vs 4.5-mm screws and the placement of fewer screws were associated with improved likelihood of racing. CONCLUSION: The prognosis for postoperative racing of thoroughbreds with dorsal C3 fractures was less favorable than that previously reported. Concurrent joint pathology, such as cartilage damage at time of surgery, affected the ability of the horse to race postoperatively. CLINICAL SIGNIFICANCE: Although internal fixation of C3 slab fractures is required to restore joint congruity, return to racing should be expected in only 42% of thoroughbreds and 67% of standardbreds.

Antebrachiometacarpal arthrodesis in five dogs.

CASE REPORTS: Five dogs (4 with severe carpal contracture, 1 with a chronically infected carpal joint) underwent antebrachiometacarpal arthrodesis. Excision of all carpal bones, except the accessory carpal bone, was done, either because of persistent infection or to allow the manus to be arthrodesed in a functional position. All five dogs developed varying degrees of soft tissue swelling of the surgical site following surgery. All five arthrodeses achieved complete osseous union within 4-67 weeks. The immediate postoperative distal radiometacarpal frontal plane angulation ranged from 1° to 19° (mean ± SD: 7 ± 8°). The immediate postoperative distal radiometacarpal sagittal plane angulation ranged from 6° to 26° (mean ± SD: 17 ± 9°). Plate coverage of the secured metacarpal bone(s) ranged from 75% to 87% (mean ± SD: 80 ± 4%). Infection necessitated plate removal in four dogs, 3-17 (mean ± SD: 8 ± 6) months following surgery and 0-15 (mean ± SD: 5 ± 7) weeks following radiographic documentation of complete osseous union. CONCLUSION: Despite one dog having marked elbow incongruency and degenerative joint disease and one dog having an ipsilateral radial nerve deficit, all five dogs improved and had acceptable limb function at the time of the final evaluation, which ranged from 25 to 296 (mean ± SD: 99 ± 111) weeks following surgery.

Effect of bandaging techniques on sub-bandage pressures in the equine distal limb, carpus, and tarsus.

OBJECTIVE: To determine the influence of 3 types of bandages on sub-bandage pressures over the distal limb, carpus, and tarsus. STUDY DESIGN: Observational study. ANIMALS: Eight healthy horses. METHODS: Each of the 6 following bandages was applied on each horse in randomized order: (1) distal limb compression bandage (DLC), (2) double layer bandage (DL), (3) inner sanctum bandage (IS), (4) carpal compression bandage (CC), (5) tarsal compression bandage (TC), and (6) adhesive elastic carpal bandage (C-ELA). Sub-bandage pressures were measured with the Picopress compression measuring system (Microlab Electonica, Nicolo, Italy) after bandage application. Carpal and tarsal bandage pressures were assessed before and after walking the horses approximately 50 m. TC pressures were also measured after creating a slit over the calcaneus. A generalized linear model was used to test the association of pressure with sensor location, bandage type, time, and potential interactions (P < .05). RESULTS: DLC (165 mmHg) and IS (167 mmHg) generated greater mean combined pressures compared with DL (146 mmHg; P = .0166). At application, CC (154 mmHg) created higher mean combined sub-bandage pressure compared with C-ELA (70 mmHg; P < .001). Pressures resulting from CC and TC decreased after walking (P < .001), whereas those associated with C-ELA were not affected. CONCLUSION: Variations to the standard DLC construct did not increase sub-bandage pressures. CC and TC pressures rapidly decreased with ambulation, whereas C-ELA pressures in healthy horses were not affected by walking. CLINICAL SIGNIFICANCE: Variations to the standard DLC offer no additional benefit in regards to increasing sub-bandage pressures. Carpal elastic bandages maintain sub-bandage pressures during ambulation and may be more appropriate for long term bandaging in ambulating horses. Creating a slit over the calcaneal tuber in TC bandages is discouraged due to rapid decreases in sub-bandage pressure.

Pancarpal and partial carpal arthrodesis with 3 locking compression plates in 6 horses.

OBJECTIVE: To report the outcome of horses after pancarpal or partial carpal arthrodesis with 3 locking compression plates (LCP). STUDY DESIGN: Case series. ANIMALS: Six horses ranging in age from 8 months to 16 years and weighing 227-580 kg with severe carpal pathology including acute fractures, chronic osteoarthritis, and chronic angular limb deformity. METHODS: Pancarpal or partial carpal arthrodesis was performed with 3 LCP. Autologous cancellous bone grafts were used in 5 of 6 cases to facilitate joint arthrodesis. RESULTS: External coaptation was maintained for 4 to 6 weeks after surgery. Radiographic follow-up was available in all 6 cases, all of which reached arthrodesis and pasture soundness by 4-5 months postoperatively. One case required implant removal at 6 months because of implant exposure through the skin but returned to pasture soundness after removal. CONCLUSION: Carpal instability due to acute fractures or chronic disease was successfully stabilized with 3 short LCP, leading to pasture soundness in all 6 horses. CLINICAL SIGNIFICANCE: The use of 3 short LCP should be considered as a strategy to facilitate pancarpal or partial carpal arthrodesis by providing superior stability without placement of implants in the diaphysis of the radius and third metacarpus.

Pancarpal Arthrodesis Without Rigid Coaptation Using the Hybrid Dynamic Compression Plate in Dogs.

OBJECTIVE: To describe the complications, short- and long-term outcomes, and owner satisfaction for dogs treated with pancarpal arthrodesis (PCA) using the 2.7/3.5 mm locking and dynamic compression plate (DCP) hybrid pancarpal arthrodesis plate (hybrid DCP [HDCP]) without rigid coaptation in the postoperative period. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs with carpal injuries requiring PCA (n=15). METHODS: Records (May 2007-October 2013) of dogs that had PCA using 3.5/2.7 mm HDCP (1 or 2 plates) and a Robert-Jones bandage were reviewed to determine intra- and post-operative complications and overall limb function. Follow-up was obtained by clinical evaluation at our institution and telephone interview of owners. RESULTS: Fourteen dogs had PCA stabilized with a single HDCP and 1 giant breed dog had PCA stabilized with 2 HDCP on the dorsal aspect of the carpus secured onto the 3rd and 4th metacarpal bones. Two dogs presented with bilateral injuries. Thirteen owners (87%) judged the results of surgery as excellent and 2 (13%) judged the results of surgery as good. Minor complications (4 limbs; 23%) were occasional episodes of mild lameness in 3 dogs and 3 episodes of discharging sinus tracts in a single dog. Major complications (3 limbs; 17%) included 1 surgical site infection and implant failure in a 43 kg dog with an active leishmaniasis infection and a concurrent bilateral sacro-iliac luxation. Two dogs developed episodes of discharging sinus tract and pain over the most distal screw that eventually necessitated plate removal. CONCLUSION: PCA without rigid coaptation can successfully be performed using the HDCP.

Investigating integument alterations in cubicle housed dairy cows: which types and locations can be combined?

In this study, a data set of 2922 lactating dairy cows in a sample of 64 conventional and organic dairy farms with Holstein Friesian cows in Germany and 31 conventional dairy farms with the dual purpose breed Fleckvieh in Austria was used to screen for correlations between the occurrences of different integument alterations. All cows were housed in cubicle systems. Alterations were classified as hairless areas (H), scabs or wounds (W) or swellings (S) and assessed at 15 locations of the cows' body. Highest median farm prevalences were found at the joints of the legs, which are already commonly included in studies on integumentary alterations: median farm prevalence was 83% for S and 48% for H at the carpal joints, followed by H (38%) and S (20%) at the lateral tarsal joints and H at the lateral calcanei (20%). Additional body parts with notable median prevalences for H were the hip bones (13%), pin bones (12%) and sacrum (11%). Three cluster models, with 2, 5 and 14 clusters, were built by hierarchical clustering of prevalences of the 30 most relevant alteration location combinations. Clustering revealed that location overruled type of lesion in most cases. Occasionally, clusters represented body segments significantly distant from each other, for example the carpal joints and lateral and dorsal calcanei. However, some neighbouring areas such as the medial and lateral hock area should be analysed separately from each other for causal analysis as they formed distinct clusters.

Relationship between serum biomarkers of cartilage and bone metabolism and joint injury in young Thoroughbred racehorses in training.

OBJECTIVE: To compare serum concentrations of biomarkers of cartilage and bone metabolism between racehorses with a carpal or metacarpophalangeal or metatarsophalangeal (ie, fetlock) joint injury and matched uninjured control horses, determine changes in biomarker concentrations following joint injury, and establish the biomarkers' diagnostic test performance. ANIMALS: 50 Thoroughbred racehorses with a carpal or fetlock joint injury and 50 matched uninjured horses (control horses). PROCEDURES: Serum concentrations of 2 cartilage synthesis biomarkers (carboxy-terminal propeptide of type II collagen [CPII] and chondroitin sulfate epitope 846 [CS846]), 2 cartilage degradation biomarkers (neoepitope generated by collagenase cleavage of type II collagen [C2C] and cross-linked carboxy-terminal telopeptide fragments of type II collagen [CTX-II]), and serum activity of a bone formation marker (bone-specific alkaline phosphatase [BAP]) were measured around the time of injury diagnosis and monthly thereafter for as long as possible. RESULTS: Injured horses as a group and horses specifically with fetlock joint injuries had significantly lower serum CPII concentrations and significantly higher serum BAP activities than matched control horses. Concentrations of CTX-II were decreased between 2 and 4 months following joint injury. Measurement of CPII concentration at baseline could distinguish between injured horses and control horses with a sensitivity of 82% and specificity of 50%. CONCLUSIONS AND CLINICAL RELEVANCE: Although significant differences in specific biomarker concentrations between horses with carpal and fetlock joint injuries and matched control horses were identified, there was no convincing evidence of the suitability of these biomarkers as diagnostic or prognostic tools in a clinical setting.

Long-term follow-up of working dogs in New Zealand following pancarpal arthrodesis using dorsal hybrid plating.

AIM: To determine the long-term prognosis for working dogs in New Zealand following pancarpal arthrodesis (PCA) utilising a dorsal hybrid plate. METHODS: Owners of 14 dogs who had a PCA performed as part of a previous study conducted at two small animal veterinary surgical hospitals were contacted via phone and asked to participate in a short survey. RESULTS: A phone survey was completed for seven dogs. Five of the seven dogs had returned to full work, one dog had a moderate persistent lameness that prevented returning to normal work and the remaining dog did not return to normal work for reasons unrelated to the study. Removal of the implants was required in four of seven cases at a median interval of 2 (min 0.5, max 2) years following surgery. One dog had no gait abnormality, but developed an occasional mild lameness after jumping, one dog had a constant gait abnormality with a moderate, persistent lameness, and the remaining five dogs had a constant gait abnormality with a mild, intermittent lameness. All owners contacted were very satisfied with the procedure. CONCLUSIONS: Working dogs undergoing a standardised surgical procedure for unilateral PCA using a hybrid carpal arthrodesis bone plate applied dorsally have a good prognosis for return to work. CLINICAL RELEVANCE: Although this study has a small number of cases, this study provides subjective longer-term follow-up data than previously reported for working dogs that have undergone PCA. Owners should be warned that plate removal may be required in approximately 60% of dogs and additional expenditure should be planned for.

Arthroscopic removal of discrete palmar carpal osteochondral fragments in horses: 25 cases (1999-2013).

OBJECTIVE: To characterize discrete palmar carpal osteochondral fragmentation in horses and to document the effect of osteoarthritis and surgical removal of these fragments on functional outcome. DESIGN: Retrospective case series. ANIMALS: 25 horses. PROCEDURES: Medical records and radiographic views were reviewed to identify horses that had radiographic evidence of palmar carpal fragmentation, which was subsequently treated by arthroscopic removal. Information collected included cause of fracture, initial and long-term clinical and radiographic findings, and functional outcome. RESULTS: Palmar carpal fragmentation of 30 carpal bones was identified in 25 unilaterally affected horses. A known traumatic event was reported to cause the fragmentation in 17 of the 25 (68%) horses. Of the 25 horses, 17 (68%) had fragmentation involving the antebrachiocarpal joint, 7 (28%) had fragmentation involving the middle carpal joint, and 1 (4%) had fragmentation involving the carpometacarpal joint. The proximal aspect of the radial carpal bone was the most commonly affected site (12/30 fragments), followed by the accessory carpal bone (6/30). Of the 25 horses, 19 (76%) were not lame (sound) after surgery and returned to their intended use, 4 (16%) were considered pasture sound, and 2 were euthanized (because of severe postoperative osteoarthritis or long bone fracture during recovery from anesthesia). Eight of the 14 horses with preoperative evidence of osteoarthritis returned to function after surgery. Twelve of 17 horses with antebrachiocarpal joint fragments and 6 of 7 horses with middle carpal joint fragments returned to their previous use. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the prognosis for horses after arthroscopic removal of palmar carpal osteochondral fragments is good. Early intervention, before the development of osteoarthritis, is recommended.

Partial carpal arthrodesis using a medially applied mini-plate in three cats with carpometacarpal hyperextension injury.

Hyperextension injury to the feline carpus usually results in disruption of the palmar ligament support at the level of the carpometacarpal joint. Treatment options include pancarpal or partial carpal arthrodesis. Partial carpal arthrodesis preserves range of motion of the antebrachiocarpal joint, and pronation and supination of the forearm. The surgical technique and three cases of partial carpal arthrodesis using medially applied mini-plates are described. Partial carpal arthrodesis of the feline carpus using medially applied mini-plates may be a safe and effective treatment for hyperextension injury to the carpometacarpal joints.

Ex vivo evaluation of carpal flexion after partial carpal arthrodesis in horses.

OBJECTIVE: To determine degrees of flexion after arthrodesis of the antebrachiocarpal (ABC) joint, middle carpal (MC), and carpometacarpal (CMC) joints combined (MC/CMC), and carpometacarpal (CMC) joint alone. STUDY DESIGN: Ex vivo study. ANIMALS: Forelimbs (n = 9) from 2- to 10-year-old Quarter Horses (5), Thoroughbred (2), and American Paint Horse (2). METHODS: Using 2 locking compression plates, 3 partial carpal arthrodesis techniques were performed. Cables and deadweights were connected to limbs and each angle of flexion determined 3 times using a protractor and then averaged. Control measurements were obtained before and after arthrodesis, the techniques randomized with Latin square design. Descriptive data were analyzed with Levene's test, Q-Q plots, ANOVA, and Bonferroni test. RESULTS: Mean ± SD carpal flexion results were: controls 150° ± 8°, CMC arthrodesis 149° ± 9°, MC/CMC arthrodesis 43° ± 7.6°, and ABC arthrodesis 25° ± 6.3°. There was no significant reduction in flexion after a CMC arthrodesis compared with controls (P = .21), but there was after ABC (P < .001) and MC/CMC arthrodesis (P < .001), with the ABC arthrodesis significantly reduced compared with an MC/CMC arthrodesis (P < .001). CONCLUSIONS: Whereas CMC arthrodesis does not affect carpal flexion, CMC/MC and ABC arthrodesis markedly reduce the degree of carpal flexion.

The effect of season and track condition on injury rate in racing greyhounds.

OBJECTIVES: To identify environmental and management factors affecting injury rate in racing greyhounds. METHODS: Surveys of racing injuries at two greyhound tracks in the UK were conducted using injury data collected by track veterinary surgeons. At Track A the relative frequency of common injuries was determined and compared with previously published studies conducted in the UK. At Track B the effects of month of the year, ambient temperature and track condition ("going") on injury rate were determined. RESULTS: Comparison of common injuries at Track A with previous studies suggested a change in the relative frequency of some injury types following a change in track surface from grass to sand. Estimated injury rates suggest improved track safety with the change in track surface. At Track B, injury rate increased significantly with faster track conditions. Time of year and ambient temperature had no significant effect on injury rate. CLINICAL SIGNIFICANCE: Changes in track maintenance resulting in a slower track may reduce injury rate in racing greyhounds, with associated welfare benefits.

Management of carpal hyperextension injury in a cat using combined temporary transarticular internal and external skeletal fixation.

This report describes the successful management of a carpal hyperextension injury in a cat using combined temporary transarticular internal and external skeletal fixation, without performing an arthrodesis. To our knowledge, there have been no previous reports of management of feline carpal hyperextension injuries in this fashion.

Carpal joint injuries in cats - an epidemiological study.

OBJECTIVE: Injuries of the carpal joint are rare in cats. The most common cause is a fall from a height, known as 'high-rise syndrome'. So far, only limited data about carpal joint injuries (CJI) in cats are available. The aim of this study was to investigate the epidemiology, aetiology, location, and type of CJI in cats. METHODS: Case records of cats diagnosed with CJI between 1998 and 2010 were retrospectively analysed. Data concerning signalment, history and type of CJI, accompanying systemic injuries and further orthopaedic injuries were collected. RESULTS: During the study period, 73 cats were diagnosed with CJI (87 injured carpal joints) and the prevalence in our hospital population was 0.26% (73 out of  28,482). Cats with CJI were more likely to be presented in the period from April-October (85%, p = 0.003) compared with the rest of the year. Carpal joint injuries were caused by a fall from a height in 72.6% of the cases. Of all carpal joints, the antebrachiocarpal joint was predominantly injured (50.6%, p = 0.001) and this was commonly caused by a fall from the fourth floor or higher (p = 0.002). The carpometacarpal joint was predominantly affected by a fall from heights up to the third floor (p = 0.004). CLINICAL SIGNIFICANCE: The data of this study confirm previous data with respect to time of occurrence and cause of injury. Of note, the height of the fall appears to influence the location of the injury within the carpus of cats.

Gene biomarkers in peripheral white blood cells of horses with experimentally induced osteoarthritis.

OBJECTIVE: To use microarray analysis to identify genes that are differentially expressed in horses with experimentally induced osteoarthritis. ANIMALS: 24 horses. PROCEDURES: During arthroscopic surgery, a fragment was created in the distal aspect of the radiocarpal bone in 1 forelimb of each horse to induce osteoarthritis. At day 14 after osteoarthritis induction, horses began exercise on a treadmill. Blood and synovial fluid samples were collected before and after surgery. At day 70, horses were euthanized and tissues were harvested for RNA analysis. An equine-specific microarray was used to measure RNA expression in peripheral WBCs. These data were compared with mRNA expression (determined via PCR assay) in WBCs, cartilage, and synovium as well as 2 protein biomarkers of cartilage matrix turnover in serum and synovial fluid. RESULTS: A metalloproteinase domain-like protein decysin-1 (ADAMDEC1), glucose-regulated protein (GRP) 94, hematopoietic cell signal transducer (HCST), Unc-93 homolog A (hUNC-93A), and ribonucleotide reductase M2 polypeptide (RRM2) were significantly differentially regulated in WBCs of horses with osteoarthritis, compared with values prior to induction of osteoarthritis. There was correlation between the gene expression profile in WBCs, cartilage, and synovium and the cartilage turnover proteins. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in WBCs were correlated when measured via microarray analysis and PCR assay. CONCLUSIONS AND CLINICAL RELEVANCE: Expression of ADAMDEC1, GRP94, HCST, hUNC-93A, and RRM2 was differentially regulated in peripheral WBCs obtained from horses with experimentally induced osteoarthritis. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in peripheral WBCs has the potential for use as a diagnostic aid for osteoarthritis in horses.