Stress fractures of the tibia and humerus in Thoroughbred racehorses: 99 cases (1992-2000).

The article studies the clinical features and results of Thoroughbred racehorses with tibial or humeral stress fractures, indicating that such injuries most commonly occur in 2-year-old or previously unraced horses and older, raced horses respectively, and that a good prognosis can generally be expected post-treatment.

Research Methodology

• The study examined 99 Thoroughbreds which had tibial or humeral stress fractures in a retrospective manner.
• Data was procured from medical records, which included the horse’s past history, signalment (detailed description of the horse), along with clinical, radiographic, and scintigraphic (a type of diagnostic test) findings.
• Outcomes of treatment were assessed via interviews with trainers, conducting follow-up examinations, and by studying race records.

Research Findings

• The study uncovered 74 tibial and 48 humeral stress fractures among the subjects. Tibial stress fractures were identified in 61 Thoroughbreds while 39 Thoroughbreds had humeral stress fractures.
• Tibial stress fractures were most prevalent in 2-year-old or unraced horses and were typically located in one of three specific areas in the tibia, the most usual being the caudolateral cortex of the mid-diaphysis.
• Humerus fractures were commonly found in one of four locations within the humerus, predominantly the caudodistal cortex, and these were more common in older horses that had raced earlier.
• Out of 58 tibial stress fractures, 44 (76%) were identified radiographically while out of 32 humeral stress fractures, 18 (56%) were recognized in this way. However, humeral stress fractures involving the caudodistal cortex could not be detected radiographically.

Treatment and Outcomes

• Treatment consisted of rest and exercise restriction. Post treatment, 49 out of 61 horses (80%) with tibial stress fractures and 30 out of 39 horses (77%) with humeral stress fractures were able to return to racing.
• There were repeated instances of humeral stress fractures in 6 horses.

Conclusion

• The study suggests that Thoroughbred racehorses are most likely to get tibial stress fractures when they are 2-years-old or unraced and humeral fractures are more common in older, previously raced horses.
• The prognosis for a successful return to racing post-treatment is generally favorable.