Clinical insights: Musculoskeletal injury in the racehorse: What is new?

Hoof slip duration at impact in galloping Thoroughbred ex-racehorses trialling eight shoe-surface combinations

Horseshoes used during racing are a major determinant of safety as they play a critical role in providing traction with the ground surface. Although excessive hoof slip is detrimental and can predispose to instabilities, falls and injuries, some slip is essential to dissipate energy and lower stresses on the limb tissues during initial loading. This study aimed to quantify hoof slip duration in retired Thoroughbred racehorses galloping over turf and artificial (Martin Collins Activ-Track) tracks at the British Racing School in the following four shoeing conditions: 1) aluminium; 2) steel; 3) GluShu (aluminium-rubber composite); and 4) barefoot. High-speed video cameras (Sony DSC-RX100M5) filmed 389 hoof-ground interactions from 13 galloping Thoroughbreds at 1000 frames per second. A marker wand secured to the lateral aspect of the hoof wall aided tracking of horizontal and vertical hoof position in Tracker software over time, so the interval of hoof displacement immediately following impact (hoof slip duration) could be identified. Data were collected from leading and non-leading forelimbs at speeds ranging from 24-56 km h-1. Linear mixed models assessed whether surface, shoeing condition or speed influenced hoof slip duration (significance at p≤0.05). Day and horse-jockey pair were included as random factors and speed was included as a covariate. Mean hoof slip duration was similar amongst forelimbs and the non-leading hindlimb (20.4-21.5 ms) but was shortest in the leading hindlimb (18.3±10.2 ms, mean ± 2.S.D.). Slip durations were 2.1-3.5 ms (p≤0.05) longer on the turf than on the artificial track for forelimbs and the non-leading hindlimb, but they were 2.5 ms shorter on the turf than on the artificial track in the leading hindlimb (p = 0.025). In the leading hindlimb, slip durations were also significantly longer for the aluminium shoeing condition compared to barefoot, by 3.7 ms. There was a significant negative correlation between speed and slip duration in the leading forelimb. This study emphasises the importance of evaluating individual limb biomechanics when applying external interventions that impact the asymmetric galloping gait of the horse. Hoof slip durations and the impact of shoe-surface effects on slip were limb specific. Further work is needed to relate specific limb injury occurrence to these hoof slip duration data.

Concurrent measurement of serum and radiomic biomarkers in the clinical investigation of equine musculoskeletal injuries: A prospective pilot study

The prevention of musculoskeletal injuries and their related welfare and economic impacts represent an immediate priority for the horse racing industry. This prospective pilot study aimed to evaluate a method to quantitatively analyze scintigraphic features of specific anatomical regions of the horse's appendicular skeleton in combination with secondary measures of musculoskeletal metabolism in blood. Twelve horses referred for scintigraphic assessment of lameness were enrolled. Blood samples were collected immediately prior to the administration of radiotracer. Serum concentrations associated with bone turnover were determined for the following biomarkers: C-terminal telopeptides of type I collagen, proteoglycans and sulfated glycosaminoglycans, collagen type II, osteocalcin, and procollagen II C-terminal propeptide. Scintigraphic images underwent radiomic analysis of discrete regions of the distal limbs and these data were correlated to bone turnover markers. Three lame horses demonstrated asymmetrical radiomic abnormalities. The concentration of osteocalcin in the lame horses was significantly higher when compared to the control group, while no significant changes were observed for the other screened serum biomarkers. Findings from the current study provided evidence that radiomic analysis of equine scintigraphy is feasible. This method has the potential to interrogate which serum markers are associated with musculoskeletal injuries.

Arthroscopic removal of osteochondral fragments located within the condylar fossa of the third metacarpus/metatarsus in Thoroughbred yearlings

OBJECTIVE

To describe an arthroscopic technique for the removal of osteochondral fragments located within the condylar fossa of the third metacarpal/tarsal bone.

STUDY DESIGN

Retrospective study.

ANIMALS

Thoroughbred yearlings (n = 11).

METHODS

Osteochondral fragments located within the condylar fossa of the third metacarpal/tarsal bone identified during presale radiographic examination were removed via arthroscopy, assisted with ultrasonography in select cases. Complete fragment removal was confirmed by intraoperative radiography.

RESULTS

Fragments were successfully removed using rongeurs following dissection of soft tissue attachments using a bipolar radiofrequency probe. No postoperative complications occurred.

CONCLUSIONS

An ipsilateral arthroscopic and instrument portal coupled with ultrasound assistance and a radiofrequency probe allowed for successful removal of fragments located within the condylar fossa of the third metacarpal/tarsal bone. The technique allowed for the removal of the unstable osteochondral fragment and associated physical debris.

CLINICAL SIGNIFICANCE

The described surgical technique enables the removal of osteochondral fragments located within the condylar fossa of the third metacarpal/tarsal bone with minimal disruption to the surrounding soft tissues.