Racing performance of Thoroughbred horses after arthroscopic surgery of the carpus

The case record, and subsequent racing performance, of 110 horses that had undergone arthroscopic surgery of the carpus, were reviewed. Of these, 87% resumed racing, with 43% able to win at least one race, after surgery. Horses with chip fractures from the distal radius had the best prognosis, while horses with sagittal fractures of the third carpal bone had the poorest. The performance of horses with bilateral lesions was similar to those with unilateral lesions. It was concluded that arthroscopic surgery was a suitable technique for the diagnosis and treatment of carpal lesions in the horse.     

Frequency distribution of carpal osteochondral fragmentation in a population of flat racing Thoroughbreds in the UK

Lameness associated with osteochondral fragmentation of the carpus is a common injury in racing horses. Frequency distributions of sites of fragmentation have previously been published in racehorses in the USA, Australia, New Zealand and Japan but not in racing Thoroughbreds in the UK. The objectives of the study were to document sites of osteochondral fragmentation in the carpus of a population of Thoroughbred flat racehorses in the UK and compare these with other Thoroughbred populations globally and other flat racing breeds. This study was a single centre retrospective observational study; case records of flat racing Thoroughbreds with sites of carpal bone fragmentation that underwent arthroscopic surgery at Newmarket Equine Hospital between 2008 and 2013 were reviewed. A total of 291 sites of fragmentation were identified arthroscopically within the carpal joints of 174 horses. This involved 135 (75%) middle carpal (MCj) and 44 (25%) antebrachiocarpal joints (ABCj), which differs from other populations reported. The most common sites of fragmentation were dorsodistal radial carpal bone (DDiCr) (49%), dorsoproximal third carpal bone (DPrC3) (22%), dorsodistal radius (DDiR) (15%), dorsoproximal radial carpal bone (DPrCr) (5%) and dorsoproximal intermediate carpal bone (DPrCi) (4%). The dorsodistal radial carpal bone is also the most common site in American (US) Quarter Horses (QHs) and Thoroughbreds (TBs) and Australian (AUS) TBs, while DPrC3 has a greater prevalence in US Standardbreds (SBs). Thereafter the frequency distribution differs between the reported study groups. Although all horses underwent bilateral radiographic examination, 45% of the total population had unilateral arthroscopic evaluation. This may therefore underestimate the total number of sites of fragmentation reported. In summary the frequency distribution of carpal fragmentation in flat racing Thoroughbreds in the UK appears to differ from other populations of racehorses.     

The use of small (2.7 mm) screws for arthroscopically guided repair of carpal chip fractures

Reasons for performing the study: Removal of large chip fractures of the carpal bones and the osteochondral deficits that result, have been associated with a worse prognosis than removal of small fragments in similar locations. Hypothesis: Reducing the articular defects by repair of large osteochondral fragments may have advantages over removal. Methods: Horses with osteochondral chip fractures that were of sufficient size and infrastructure to be repaired with small (2.7 mm diameter) AO/ASIF cortex screws were identified and repair effected by arthroscopically guided internal fixation. Results: Thirty‐three horses underwent surgery to repair 35 fractures of the dorsodistal radial carpal bone (n = 25), the dorsal margin of the radial facet of the third carpal bone (n = 9) and the intermediate facet of the distal radius (n = 1). There were no surgical complications and fractures healed satisfactorily in 26 of 28 horses and 23 horses returned to racing performance. Conclusion: Arthroscopically guided repair of carpal chip fractures with small diameter cortex screws is technically feasible and experiences with 33 cases suggest that this may have advantages over fragment removal in managing such cases. Potential relevance: Surgeons treating horses with large chip fractures of the carpal bones should consider arthroscopically guided internal fixation as an alternative to removal.     

Surgical and nonsurgical management of sagittal slab fractures of the third carpal bone in racehorses: 32 cases (1991-2001)

OBJECTIVE: To compare results (ie, return to racing and earnings per race start) of surgical versus nonsurgical management of sagittal slab fractures of the third carpal bone in racehorses. DESIGN: Retrospective study. ANIMALS: 32 racehorses (19 Thoroughbreds, 11 Standardbreds, and 2 Arabians). PROCEDURE: Medical records and radiographs were reviewed to obtain information regarding signalment and treatment. Follow-up information was obtained from race records. Robust regression analysis was performed to evaluate earnings per start in horses that raced at least once before and after injury. RESULTS: 22 (69%) horses raced at least once after treatment of the fracture. All 7 horses treated by means of interfragmentary compression raced after treatment, and horses that underwent interfragmentary compression had significantly higher earnings per start after the injury than did horses treated without surgery. Eight of 9 horses treated by means of arthroscopic debridement of the damaged cartilage and bone raced after treatment, but only 7 of 16 horses treated without surgery (ie, stall rest) were able to return to racing after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that racehorses with sagittal slab fractures of the third carpal bone have a favorable prognosis for return to racing after treatment. Horses treated surgically were more likely to race after treatment than were horses treated without surgery.     

A retrospective evaluation of the surgical management of equine carpal injury

SUMMARY: Records of 220 thoroughbred horses presented to the Randwick Equine Centre or the University of Queensland Veterinary Teaching Hospital for surgical management of carpal injury were reviewed. Details of racing performance were obtained, enabling evaluation of racing success following surgery. Age and sex matched control horses not known to have suffered carpal injury were selected from the Australian Stud Book and the Australian Racehorse Register. Control and treated populations were compared in terms of overall career racing success.
Radiographs or xeroradiographs from 198 horses were available for evaluation. The dorsomedial aspects of the distal articular surface of the radial carpal bone and the proximal articular surface of the third carpal bone were the most commonly observed locations of osteochondral fracture. Bilateral carpal injury was found to be sufficiently common to warrant routine radiographic examination of both limbs. The dorsolateral-palmaromedial oblique, flexed lateral and dorsoproximal-dorsodistal oblique (skyline) projections were the most useful views for evaluation of carpal degenerative joint disease. Surgical removal of osteochondral fractures by arthrotomy or arthroscopy was found to be a suitable method of treatment.
Arthroscopy was associated with a significantly shorter convalescent period than arthrotomy. Seventy-six percent of the treated population returned to racing following surgery. Average earnings following surgery were 20 000. However, the median value was only 1400 and 48% of the treated population failed to earn more than 1000. Male horses in both the treated and control groups performed significantly better than females. Treated horses performed significantly better than the randomly selected control population.     

Surgical repair of radial carpal bone fractures in two racehorses

A 3-year-old Standardbred gelding (Case 1) and a 2-year-old Thoroughbred gelding (Case 2) were referred for surgical evaluation of a left radial carpal bone (RCB) fracture, sustained during training. Clinical findings at the time of initial examination included a palpable effusion within the left middle carpal joint in both horses and marked signs of pain and reduced range of motion on flexion of the affected carpus. In both horses, the RCB fracture was evident on the following radiographic views of the carpus: dorsolateral–palmaromedial oblique (30° off lateromedial) and flexed lateromedial. An additional loose wedge-shaped osteochondral fragment at the proximal articular surface of the RCB could be seen in Case 2. Both horses underwent surgical reduction and repair of the fracture between 1 and 2 days following the initial injury, which consisted of arthroscopic removal of any intra-articular osteochondral fragments, and arthroscopic assisted-interfragmentary compression via a standard dorsomedial and dorsolateral approach to the antebrachiocarpal joint (ACJ) and middle carpal joints (MCJ). The two horses returned to function as racehorses, 6 months (Case 1) and 16 months (Case 2) after surgery. The RCB is a relatively uncommon site for large carpal fractures in horses. The clinical presentation and findings from this report were similar to that of third carpal bone (C3) slab fractures, confirming that surgical repair is indicated in selected cases of RCB fractures.     

Survey of arthroscopic surgery for carpal chip fractures in thoroughbred racehorses in Japan

Medical and racing records of 155 Thoroughbred racehorses that underwent arthroscopic surgery for carpal chip fractures were investigated. Articular damage for 98.4% of the fractures was classified as G1 or G2 using McIlwraith's criteria. The rate of return to racing after surgery was 82.6%. Evaluation of racing performance after surgery was attempted using a placing index (PI) based on race finish position. There was no significant difference in the PI distribution between horses that underwent surgery and other healthy horses.     

Palmar carpal osteochondral fragments in racehorses: 31 cases (1994-2004)

OBJECTIVE: To evaluate records of racehorses with palmar carpal osteochondral fragments and determine whether the fragments were indicators of the severity of pathologic joint changes or prognosis. DESIGN: Retrospective case series. ANIMALS: 31 racehorses. PROCEDURES: Medical records, radiographs, and videos of arthroscopic procedures were reviewed. Information gathered included signalment; location, number, and size of the primary lesion; number and size of palmar carpal fragments; and details pertaining to surgical procedures. Outcome variables were obtained from race records. RESULTS: 31 horses met the selection criteria. Multiple palmar fragments were diagnosed in 58% of horses; small fragments (< 3 mm in diameter) were most common (52% of horses). Fifty-two percent of the horses returned to racing, 48% returned to racing and earned money, and 32% had at least 5 more starts. Horses with multiple fragments had significantly less earnings per start and lower performance index values after surgery than those with 1 fragment. Horses with palmar fragments < 3 mm in diameter were significantly less likely to return to racing and have 5 starts or to win money after surgery than horses with larger fragments. CONCLUSIONS AND CLINICAL RELEVANCE: Palmar carpal osteochondral fragments can be used as an indicator of clinically important joint pathology and as a prognostic indicator in racehorses. Horses with multiple small fragments were less likely to successfully return to racing than horses with only dorsally located carpal fragments or horses with 1 or 2 large palmar fragments. When possible, removal of palmar carpal osteochondral fragments should be considered.     

Heritability estimates of fractures in Japanese Thoroughbred racehorses using a non‐linear model

Thoroughbred racehorses are produced by mating small numbers of Arabian stallions and native British mares, and have been improved by selection of horseracing performance for about 300 years. While these improvements led to good performance as racehorses, they exposed horses to numerous medical disorders, aggravated by extensive exercise. Fractures are frequent medical disorders in Thoroughbred racehorses. In this study, fracture heritability was estimated using 3,927 Japanese Thoroughbred racehorses to elucidate the risk of racehorse fractures. The heritability estimates of all examined fractures were low (h² = 0.06), while those of fractures in carpal bone and carpus (carpal bone plus distal radius) were moderate (h² = 0.37, 0.24, respectively). Fracture occurrence age for carpal bone and distal radius was both 3.3 years old and was younger than that for other fractures. These results indicated that a larger proportion of the variation in the studied population was due to genetic factors for carpal fractures than for other fractures, while the fractures at other bones were largely affected by environmental factors, correlated with the athlete period (number year in racing). These findings contribute to develop a management plan for suppressing racehorse fractures and improving horseracing safety.     

Qualitative and quantitative documentation of the racing performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986-1995)

The purpose of this study was to examine the longevity of postoperative careers and quality of performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx (P1) osteochondral fractures. Six hundred and 59 dorsoproximal P1 chip fractures were removed arthroscopically from 574 joints in 461 horses presented for lameness or decreased performance attributed to the chip fractures. Radiological and arthroscopic examination revealed an average of 1.43 fragment sites/horse, 1.15 fragment sites/joint and 1.25 affected joints/horse. Eighty-nine percent of the horses (411/461) raced after surgery and 82% (377/461) did so at the same or higher class. Fifty horses did not race after surgery. Sixty-eight percent of the horses raced in a Stake or Allowance race postoperatively. Data, previously undocumented, establishes that the quantity and quality of performance is not diminished after arthroscopic treatment of dorsoproximal P1 fragmentation. Surgical removal of chip fractures is a means of preserving the economic value of an injured Thoroughbred, allowing a rapid and successful return to racing at the previous level of racing performance.     

Osteochondral fragmentation of the plantar/palmar proximal aspect of the proximal phalanx in racing horses

SUMMARY The clinical presentation and outcome of treatment is presented for 26 cases of osteochondral fragmentation of the plantar/palmar proximal aspect of the proximal phalanx. Twenty-three were racing Standardbreds and three were racing Thoroughbreds. The most common reason for presentation was an inability to run straight at high speed. Only eight horses presented for lameness, although on examination 19 were lame. A positive flexion test was recorded in 90% of affected fetlock joints and effusion in 48%. Arthroscopic fragment removal was performed on 23 occasions in 21 horses and arthrotomy in one horse. Of the 16 horses that had returned to racing, 12 had improved their performance, while three showed no improvement, and one was retired for other reasons. In three horses refragmentation occurred after surgery, two of which had improved after initial arthroscopic removal. Degenerative changes within the fetlock joint were detected at surgery in eight horses. Of the four horses treated conservatively, one returned to its previous level of performance temporarily after intra-articular medication, one showed no improvement and two were still resting. Plantar/palmar osteochondral fragmentation of the proximal aspect of the first phalanx is a common cause of low-grade lameness in racing horses, and arthroscopic removal results in improvement in race performance in a high percentage of cases.     

Subchondral lucency of the third carpal bone in Standardbred racehorses: 13 cases (1982-1988)

Thirteen Standardbreds had subchondral lucency of the third carpal bone (C3), described as single or multiple central areas of C3 bone loss in the radial fossa. Sclerosis of the radial fossa was also detected. The mean age of 9 stallions, 3 mares, and 1 gelding was 4.1 years (range, 3 to 7 years). All horses had an acute moderate to severe lameness referable to the middle carpal joint. A dorsoproximal dorsodistal (skyline) radiographic projection was most useful and identified mild (3 horses), moderate (6 horses), and severe (4 horses) subchondral lucency and sclerosis of the radial fossa. The margin of C3 was intact dorsal to the lucent areas in all horses. In 12 horses, arthroscopic surgical evaluation and curettage of the lesion were performed. Of the 9 horses monitored long enough to allow racing, 8 horses (89%) returned to racing, although only 6 (75%) raced at the same degree of competition. Subchondral lucency of C3 resulted from chronic damage to C3 with subsequent osteochondral collapse or acute C3 proximal surface osteochondral fracture.     

Nonsurgical management of type II fractures of the distal phalanx in 48 Standardbred horses

OBJECTIVE: To evaluate nonsurgical management of type II fractures of the distal phalanx in Standardbred horses. DESIGN: Retrospective study of 48 affected horses. RESULTS: Most fractures occurred on the lateral palmar process of the left forelimb or the medial palmar process of the right forelimb; 81% of horses were considered sound enough to return to training and 63% raced. Of those returning to racing, 41% competed in > 10 races, 37% in 2 to 10 races and 22% in only 1 race. There was no difference in performance before and after fracture. Twenty-four of 25 horses had a bar shoe fitted for > 50% of the treatment phase. Of those horses returning to training without a bar shoe, 89% refractured at the same site. Sixty percent of horses returning to training with a bar shoe raced successfully. The total convalescent time, the time rested in a box and the time spelled in a paddock were similar for horses returning to racing and those that did not. The age of the horse had no effect on the ability to return to racing. CONCLUSION: The prognosis for type II fractures of the distal phalanx is guarded. It is advisable to fit a bar shoe on the horse during convalescence. Horses returning to training and racing with a bar shoe appear less likely to refracture the distal phalanx. Those horses that return to racing can perform at a level similar to that prior to fracture.     

Fractures of the palmar aspect of the carpal bones in horses: 10 cases (1984-2000)

OBJECTIVE: To determine clinical and radiographic findings, treatment, and outcome of horses with fractures of the palmar aspect of the radial carpal bone, with or without concurrent fractures of the palmar surfaces of the other carpal bones. DESIGN: Retrospective study. ANIMALS: 10 horses. PROCEDURE: Medical records were reviewed to obtain information on history, signalment, clinical and radiographic findings, treatment, and outcome. Follow-up information was gathered from owners and referring veterinarians. RESULTS: 7 horses became lame after recovery from general anesthesia for treatment of an unrelated problem. The remaining 3 horses developed a fore-limb lameness after falling (1 horse) or being turned out in a pasture (2 horses). Fractures involved the palmar surface of the radial carpal bone in all 10 horses; in addition, the ulnar carpal bone was affected in 2 horses, the intermediate carpal bone in 2 horses, and the distal aspect of the radius in 4 horses. None of the 4 horses treated nonsurgically returned to work, and 3 were euthanatized because of recalcitrant lameness. In the other 6 horses, fragments were removed surgically. Two were euthanatized because of continued lameness, 1 was euthanatized for other reasons, 2 were sound enough for light work, and 1 returned to athletic work. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that fractures of the palmar aspect of the carpal bones are uncommon in horses. The prognosis appears to be poor for affected horses but may be better for horses that undergo arthroscopic removal of intra-articular fragments.     

Arthroscopic approaches to the palmar aspect of the equine carpus

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

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in Thoroughbred horses age > or = 2 years: 84 cases (1989-2002)

REASONS FOR PERFORMING STUDY: Studies have shown that surgical removal of apical fracture fragments in Standardbred racehorses carries the best prognosis for return to racing performance, but there are no reports involving mature Thoroughbred (TB) racehorses. OBJECTIVES: To describe the incidence of apical proximal sesamoid fractures in TB racehorses and determine probability and quality of racing performance after arthroscopic removal of such fractures in TB racehorses age > or = 2 years. METHODS: Medical records and pre- and post operative race records of TB racehorses age > or = 2 years that underwent arthroscopic surgery for removal of apical proximal sesamoid fracture fragments were reviewed. RESULTS: Sixty-four percent of fractures occurred in the hindlimbs and 36% in the forelimbs. Horses with forelimb fractures had a reduced probability of return to racing (67%) compared to those with hindlimb fractures (83%), but the majority (77%) of treated horses recovered to return to race post operatively. Horses with medial forelimb fractures raced at only a 47% rate; those with suspensory desmitis at 63%. Unlike Standardbreds, there was no difference in probability of racing post operatively between horses that had, and had not, raced preoperatively. CONCLUSIONS: Data show that arthroscopic removal of apical proximal sesamoid fracture fragments is successful at restoring ability to race in skeletally mature TB horses without evidence of severe suspensory ligament damage. Prognosis for return to racing is excellent (83%) in horses with hindlimb fractures and good (67%) in those with forelimb fractures. Medial fractures of the forelimb have the worst prognosis. POTENTIAL RELEVANCE: The determination of prognosis for differing sites in TB racehorses should increase knowledge of apical proximal sesamoid bone fractures and improve communication from veterinarian to owner, and trainer, on the potential for arthroscopic restoration of the ability to race.     

Effect of third carpal slab fracture and repair on racing performance in Thoroughbred horses: 31 cases (1977-1984)

Between 1977 and 1984, 31 Thoroughbred horses (mean age, 2.8 years) were surgically treated for slab fractures of the third carpal bone. All fractures involved the articular surfaces of the intercarpal and the carpometacarpal joints in a frontal plane and had a cuboidal or slab shape. In 20 of the horses, the bone was fractured during racing and in 8 of the horses, the bone was fractured during race training. The right limb was affected more frequently than was the left limb (24 vs 7, P less than 0.05). Twenty-one (67.6%) horses raced at least once after recovery from the surgery. Data were available from 11 claiming horses that had raced at least twice before their injuries and 4 times after recovery. A claiming horse is one that competes where any horse entered is subject to being purchased for the designated amount of the claiming race; therefore, each race tends to automatically attract entrants of similar ability. In this group of 11 horses, claiming value decreased from a mean of $13,900 to a mean of $6,500 (P less than 0.05), and the mean finish position was 5.8 +/- 3.16 before injury and 5.8 +/- 3.30 after recovery. The mean claiming value for horses that had not raced before injury, but had raced after recovery (n = 5) was $8,150.     

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in Thoroughbred horses age < 2 years: 151 cases (1989--2002)

REASONS FOR PERFORMING STUDY: Studies on arthroscopic removal of apical proximal sesamoid fracture fragments in Thoroughbred (TB) horses age > or = 2 years have reported a high success rate. However, there are no reports documenting the racing prognosis of TB horses that undergo such surgery as weanlings or yearlings. OBJECTIVES: To describe the incidence of apical proximal sesamoid fractures in immature TB horses, age < 2 years and determine probability and quality of racing performance after arthroscopic removal of such fractures in 151 TB weanlings and yearlings. METHODS: The medical records of TB horses age < 2 years that underwent arthroscopic surgery for removal of apical proximal sesamoid fracture fragments were reviewed. Follow-up information was obtained from race records. Student's t tests were used to compare performance variables of operated racehorses to that of their maternal siblings. RESULTS: Ninety-two percent (139/151) of fractures occurred in the hindlimbs and 8% (11/151) in the forelimbs (fracture of both fore- and hindlimb, n = 1). Horses with forelimb fractures had a greatly reduced probability of racing (55%) compared to those with hindlimb fractures (86%). Overall, 84% of the horses raced post operatively and had performance records similar to that of their maternal siblings, 78% (787/1006) of which raced. CONCLUSIONS: Arthroscopic removal of apical proximal sesamoid fracture fragments in TB weanlings and yearlings carries an excellent prognosis for racing in horses with hindlimb fractures and a reduced prognosis in those with forelimb fractures. Medial fractures of the forelimb carry the worst prognosis. POTENTIAL RELEVANCE: The determination of prognosis increases knowledge on apical sesamoid bone fractures and potential for arthroscopic restoration of the ability to race; and enables the value of yearlings for subsequent sale to be established.     

Correlation between radiographie and arthroscopic findings in the equine carpus

The radiographic and arthroscopic findings in 150 carpal joints in 114 lame horses were compared. Chip, slab, or sagittal fractures were identified in 130 (87%) joints. In 101 (78%) of these there was good agreement between radiographic and arthroscopic findings on the number and position of fractures. In 23 (18%) joints, chip fractures additional to those seen radiographically were found arthroscopically. In one joint a large chip fracture from the craniolateral aspect of the distal radius was identified only by arthroscopy, while in 6 joints fractures were identified only by radiography. Observed causes of lameness, other than intra-articular fractures, included degenerative joint disease, synovitis, ruptured intra-carpal ligaments, and haemarthrosis. Correlation between the radiographic and arthroscopic assessment of degenerative joint disease was poor. It was concluded that both radiography and arthroscopy should be used to obtain the most accurate assessment of the equine carpus.     

Sagittal fractures of the third carpal bone in horses: 12 cases (1977-1985)

Third carpal sagittal fractures were found to be related to racing injuries in 10 of 12 horses. These fractures occurred most commonly on the medial aspect of the bone. A dorsoproximal-dorsodistal view of the carpus was required to visualize the fracture in all cases. Healing of the fracture required periods of rest of up to one year. Conservative management of these fractures resulted in return to function in 7 of 12 horses.