A 10‐year study of arthroscopic surgery in racing Thoroughbreds and Quarter Horses with osteochondral fragmentation of the carpus

Abstract

Summary Background Osteochondral fragmentation of the carpus is a common cause of lameness in racehorses. Prognosis following arthroscopic removal of the fragments was reported in 1987, but little is known of recent success rates. Objective To identify associations between the severity and location of osteochondral fragments in the carpus, and to describe the racing performance of horses pre‐ and post‐surgery in Thoroughbreds and Quarter Horses. To identify factors associated with a horse racing post‐surgery. Study design Retrospective study of clinical records (2006–2016). Methods Surgical and racing records for racehorses undergoing arthroscopic surgery of the carpus were collated during the 10‐year study period. Signalment, location of osteochondral fragmentation and grade of defect left after removal and debridement identified and racing performance pre‐ and post‐surgery were described, stratified by breed. Logistic regression analysis was used to identify factors associated with unsuccessful return to racing. Results In total, 828 horses (n = 416 Quarter Horses; n = 412 Thoroughbreds) underwent 880 carpal arthroscopies after fragments were found on radiography. Sixty‐five percent (n = 289) and 27% (n = 118) of the lesions were bilateral in Quarter Horses and Thoroughbreds respectively (P<0.001). In both breeds, the most commonly affected bone was the dorsodistal radial carpal bone (n = 320/659; 48.6%). Overall, 82% (n = 686; n = 358 Quarter Horses, n = 328 Thoroughbreds) of horses raced post‐surgery, with 69.5% (n = 476; n = 228 Quarter Horses, n = 248 Thoroughbreds) racing at the same or a higher level of competition. Factors associated with horses not returning to racing post‐surgery were increasing horse age, female horses, and a lesion grade of 4, while racing pre‐surgery was protective. Main limitations This study does not include a control population for comparison. Conclusions There were significant differences between the location and severity of lesions in Quarter Horses, when compared to Thoroughbreds. The majority of horses return to racing following surgery, although performance was influenced by lesion severity. The Summary is available in Portuguese ‐ see Supporting information

Synovial Fluid Mitochondrial DNA Concentration Reflects the Degree of Cartilage Damage After Naturally Occurring Articular Injury

“…In our cases of naturally occurring intra-articular injury, we found no correlation between mtDNA concentration and radiographic changes, but a strong association with the degree of cartilage damage detected during arthroscopic evaluation. This finding is significant because racehorses with carpal osteochondral fragments and mild concurrent cartilage damage return to racing at a significantly higher rate than those with more severe cartilage damage (44, 66) . However, radiographic and arthroscopic findings are often disparate in early joint disease, with arthroscopic findings tending to be more severe and of more prognostic value (44, 67–69) .…”

“…This finding is significant because racehorses with carpal osteochondral fragments and mild concurrent cartilage damage return to racing at a significantly higher rate than those with more severe cartilage damage (44, 66) . However, radiographic and arthroscopic findings are often disparate in early joint disease, with arthroscopic findings tending to be more severe and of more prognostic value (44, 67–69) . Thus, synovial fluid mtDNA concentration may provide a less invasive and expensive means to gain valuable prognostic information that could inform therapeutic decisions.…”

“…However, radiographic and arthroscopic findings are often disparate in early joint disease, with arthroscopic findings tending to be more severe and of more prognostic value (44,(67)(68)(69). Thus, synovial fluid mtDNA concentration may provide a less invasive and expensive means to gain valuable prognostic information that could inform therapeutic decisions.…”

A threshold volume of 10 ml is suggested for detecting articular cartilage defects in equine carpal joints using CT arthrography: Ex vivo pilot study

“…Cartilaginous defects arise as a result of continuous repetitive stress to the cartilage and subchondral bone, osteochondral fragmentation, OA, and fractures, which frequently occur on the dorsal aspect of the third carpal, radial carpal, intermediate carpal cuboidal bones, and distal radius in racehorses undergoing strenuous exercise. [29][30][31][32][33][34][35][36][37][38] Osteochondral fragmentation occurs in 35-52% of racing Thoroughbreds. [31][32][33][39][40][41] Osteoarthritis is a major welfare and economic concern in the equine industry 34 causing an estimated 60% of all lameness.…”

Highlights of recent clinically relevant papers

“…This retrospective study by Robyn Graham and colleagues in the UK, China and the USA aimed to identify associations between the severity and location of osteochondral fragments in the carpus and to describe the racing performance of horses pre‐ and post‐arthroscopic removal in Thoroughbreds and Quarter Horses .…”