Osteochondral fragments involving the dorsomedial aspect of the proximal interphalangeal joint in young horses: 6 cases (1997–2006)

Radiographic prevalence of juvenile osteochondral conditions of the proximal interphalangeal joint of Australian Thoroughbred racehorse yearlings and associations with sales results and race performance

Objectives

Ascertain the radiographic prevalence and variation in characteristics of juvenile osteochondral conditions (JOC) in the proximal interphalangeal joint (PIPJ) of Australian Thoroughbred racehorse yearlings. Establish whether there are any significant associations with public auction sale results and racing performance.

Methods

Retrospective evaluation of 1,098 yearling repository radiograph sets. Comparison of sales results and whole career racing performance of the case group with two control groups: maternal siblings (N = 397) and yearlings without PIP JOC (N = 391).

Results

6.3% of yearlings had at least one PIPJ JOC lesion with 4.8% having subchondral lucencies of the proximal phalanx (P1SC), 0.6% with subchondral lucencies of the middle phalanx (P2SC) and 0.8% with osteochondral fragmentation (OCF). P1SC were more prevalent in forelimbs and P2SC and OCF were more commonly located in the hindlimbs. 51% of PIPJ JOC were not identified on a lateromedial projection (LM). A significantly lower proportion of horses with OCF were successfully sold at public auction (p ≤ 0.05) but there was no significant difference in sales price between the case group and controls. A lower proportion of horses with PIPJ JOC made it to the racetrack to race, although this was not statistically significant. There was no significant difference in racing performance between the case group and controls, although there was a trend toward case horses earning lower career prize money and lower prize money per race (p ≤ 0.1). Lesions located in a dorsal or palmar/plantar location on the LM projection earned a lower average prize money per race (p ≤ 0.05) than those in a central location, and showed a trend toward earning lower total prize money (p ≤ 0.1) and number of places (p ≤ 0.1). There was no significant difference in performance for horses with lesions at the medial, axial or lateral aspects of the articular surface.

Clinical importance

Overall, the findings of this study indicate that the presence of PIPJ JOC in radiographs of Thoroughbred yearlings should be attributed a low to moderate risk to future racing performance, however certain lesion characteristics may be associated with decreased performance.

Osteochondral fragments of the pastern joint at the origin of the collateral ligament of the distal sesamoid bone: performance after arthroscopic removal (2000-2015)

OBJECTIVE

To describe the presence of fragments in the dorsal proximal interphalangeal (PIP) joint and to report flat racing performance after surgical treatment.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Thirty-nine affected thoroughbred flat racehorses and 169 age- and sex-matched maternal siblings.

METHODS

Medical records from 2000 to 2015 were reviewed for thoroughbred horses that underwent arthroscopic removal of osteochondral fragments in the dorsal aspect of the PIP joint. The horses' 2-year-old year, 3-year-old year, and career athletic performances were compared with their matched siblings.

RESULTS

Thirty-nine thoroughbred horses were included, varying in age from 4 months to 4 years, with osteochondral fragments in 42 PIP joints. Hind limbs (92%) were more commonly affected than forelimbs (8%). Fragments were located within the origin of the collateral ligament of the distal sesamoid (navicular) bone. After surgery, the likelihood of starting a race did not differ between treated horses (27/39 [69%]) and maternal siblings (129/169 [76%], P = .15). Race earnings did not differ between treated horses and their siblings during their 2-year-old year (P = .66), 3-year-old year (P = .43), or career (P = .60).

CONCLUSION

Removing osteochondral fragments from the origin of the collateral ligament of the distal sesamoid bone did not impair the ability to race or earning potential for affected thoroughbred racehorses compared with their maternal siblings.

CLINICAL SIGNIFICANCE

Fragments from the dorsal aspect of the PIP joint in racehorses can be removed arthroscopically resulting in a good clinical outcome and future flat racing performance comparable to matched controls.