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

Athletic prognosis following arthroscopic removal of osteochondral fragments of the proximal dorsal sagittal ridge of the fetlock in Thoroughbreds intended for flat racing

OBJECTIVE

To establish racing prognosis in Thoroughbred yearlings with proximal sagittal ridge osteochondral lesions and compare them to dorsoproximal and palmar/plantar first phalanx osteochondral lesions.

ANIMALS

A total of 47 horses had proximal sagittal ridge lesions, 34 had palmar/plantar first phalanx lesions, and 115 had dorsoproximal first phalanx lesions.

STUDY DESIGN

Retrospective case series.

METHODS

Medical records of Thoroughbred yearling racing prospects treated arthroscopically for fetlock osteochondral lesions were reviewed. Data were collected from a public database, including the ability to train and race, earnings, starts, wins, and placed races. Racing prognosis was analyzed and compared between three lesion locations.

RESULTS

Of the proximal sagittal ridge group, 76.6% raced, 65.71% of the palmar/plantar first phalanx group, and 74.58% of the dorsoproximal first phalanx group. Career length was similar for all lesions. A lower number of "starts" in the group "five years old and older" was found for the dorsoproximal first phalanx group compared to the cohort with proximal sagittal ridge lesions. Mares had more "earnings" at two years old but fewer "starts" at "five years old" compared to colts and geldings. Forelimb lesions were predictive for fewer total career starts.

CONCLUSION

Proximal sagittal ridge lesions had similar prognoses to dorsoproximal and palmar/plantar first phalanx lesions. In older horses, there was an increase in the number of starts for the proximal sagittal ridge group compared to the dorsoproximal first phalanx group. Mares and forelimb lesions were associated with decreased racing starts.

CLINICAL SIGNIFICANCE

These findings aid in prognostication for Thoroughbreds with osteochondral lesions removed arthroscopically in the fetlock joint.

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.

Ultrasound assisted arthroscopic approach for removal of basilar sesamoid fragments of the proximal sesamoid bones in horses

OBJECTIVE

To describe an ultrasound assisted arthroscopic approach for removal of non-articular basilar sesamoid fragments in Thoroughbred yearlings.

ANIMALS

Thoroughbred yearlings (n = 7).

METHODS

Basilar sesamoid fragments identified during pre-sale radiographic examination were removed using a palmar/plantar arthroscopic approach to the fetlock joint and ultrasonographic guidance. Complete fragment removal was confirmed by ultrasonography and radiography.

RESULTS

Basilar sesamoid fracture fragments were localized and removed successfully using rongeurs and a radiofrequency probe for soft tissue dissection of the fragment. Complete fragment removal was confirmed by ultrasonography and radiography. No intra- or postoperative complications occurred. At 6-8 months follow-up, no fragments or bony proliferation at the base of the sesamoid was observed.

CONCLUSIONS

Ultrasonographic guidance can be used to facilitate localization, dissection, and confirmation of removal of basilar fragments of the proximal sesamoid bone.

Prevalence of abnormal radiographic findings in 2-year-old Thoroughbreds at in-training sales and associations with racing performance

OBJECTIVE

To estimate the prevalence of radiographic abnormalities (lesions) in Thoroughbred racehorses at 2-year-old in-training sales and determine whether these lesions and 1-furlong presale workout times were associated with subsequent racing performance.

DESIGN

Retrospective cohort study.

ANIMALS

953 Thoroughbreds.

PROCEDURES

Repository radiographs of carpal, metacarpophalangeal and metatarsophalangeal (fetlock), stifle, and tarsal (hock) joints were examined. Horses with lesions were classified by lesion type and location. Race performance variables were compared between horses with and without lesions and between horses categorized by 1-furlong presale workout times (< or ≥ 11 seconds).

RESULTS

299 horses had ≥ 1 lesion, and 654 had no lesion detected. Odds of starting a race and of earning money racing were lower for horses with any lesion and lower for horses with proximal phalangeal dorsoproximal articular margin chip fracture, proximal sesamoid bone fracture or sesamoiditis, or wedge-shaped central or third tarsal bones, compared with horses that had no lesion. For horses that raced, proximal phalangeal dorsoproximal articular margin chip fractures were associated with lower lifetime earnings, and flattening of the medial femoral condyle was associated with fewer 3-year-old racing starts, compared with values for horses that had no lesion. Horses with workout times < 11 seconds had greater odds of having lifetime starts, lifetime earnings, and maximum purse above threshold (median) values than did horses with slower workout times.

CONCLUSIONS AND CLINICAL RELEVANCE

No radiographic lesions prevented all affected horses from racing. Among horses that raced, few differences were found in performance for horses with and without lesions.

Size and geometry of apical sesamoid fracture fragments as a determinant of prognosis in Thoroughbred racehorses

REASON FOR PERFORMING STUDY

Analysis was performed to examine a method for refining the preoperative prognosis for horses that had surgery to remove apical fractures of the proximal sesamoid bones (PSBs).

OBJECTIVES

To determine if: 1) there was a difference in size or configuration of apical fractures between the different anatomical locations of the PSBs, which have been shown to affect the prognosis; and 2) the size or configuration could predict the prognosis for racehorses with these fractures.

METHODS

The study included 110 weanlings and yearlings and 56 training racehorses that underwent surgery to remove apical PSB fractures. Radiographs of the fractures were used for measurement of the abaxial and axial proportion and the abaxial to axial ratio, and race records were used to determine average earnings per start (AEPS) and total post operative starts. Analysis of variance and regression statistics were used to compare the fragment sizes between the specific PSBs on each of the limbs and compare size and configuration of the fractures to prognosis.

RESULTS

There was a significantly larger abaxial to axial ratio (more transverse fracture) for the forelimb medial sesamoids than for all other sesamoids in untrained racehorses (P = 0.03). There were no other significant differences in size. There was no relationship between fracture size or configuration and AEPS nor total post operative starts.

CONCLUSIONS

Apical fractures in weanlings and yearlings tend to be more transverse in the forelimb medial PSBs than the other PSBs. Apical fracture size and geometry does not determine prognosis for apical sesamoid fractures.

POTENTIAL RELEVANCE

Horses that undergo surgery to remove larger apical fractures of the PSBs do not have a worse outcome than those horses with smaller fractures.

Relationships between race earnings and horse age, sex, gait, track surface and number of race starts for Thoroughbred and Standardbred racehorses in North America

REASONS FOR PERFORMING STUDY

There is no consensus on objective outcome measures that can be used to determine if a medical or surgical treatment affects race performance.

OBJECTIVE

To determine the association between 2 commonly used outcome measures (total starts and total earnings) and age, sex, gait and race surface.

METHODS

A cross-sectional study was performed using the race performance data for all Thoroughbred horses age 2, 3, 4 and 5 years racing in the United States, and Standardbred horses of the same ages racing in the United States and Canada during the year 2006. Median earnings and starts were determined for each combination of age, sex and track surface (for Thoroughbred) or gait (for Standardbred). The effect these variables had on starts on race earnings ($) was determined using linear regression.

RESULTS

Race records for 68,649 Thoroughbreds and 25,830 Standardbreds were obtained. All independent variables (age, breed, sex, gait, track surface and total number of starts) had a significant impact on total earnings (P<0.0001).

CONCLUSIONS

The data show considerable variation across age groups and track surfaces for Thoroughbreds and across age groups for Standardbreds. They also show that the decision to use earnings or starts as outcome measures could have a marked effect on reported success for a particular treatment.

POTENTIAL RELEVANCE

Both earning and start data should be reported in studies evaluating outcome following surgery or other intervention. Considerations of age, breed, sex, track surface and gait should be included in the design of these studies.