Imaging and histological features of central subchondral osteophytes in racehorses with metacarpophalangeal joint osteoarthritis
Version of Record online: 5 JAN 2010
2009 EVJ Ltd
Equine Veterinary Journal
Volume 41, Issue 9, pages 859–864, December 2009
How to Cite
OLIVE, J., D'ANJOU, M.-A., GIRARD, C., LAVERTY, S. and THEORET, C. L. (2009), Imaging and histological features of central subchondral osteophytes in racehorses with metacarpophalangeal joint osteoarthritis. Equine Veterinary Journal, 41: 859–864. doi: 10.2746/042516409X448481
- Issue online: 5 JAN 2010
- Version of Record online: 5 JAN 2010
- [Paper received for publication 23.09.08; Accepted 18.03.09]
- central subchondral osteophyte;
Reasons for performing study: Marginal osteophytes represent a well known component of osteoarthritis in man and animals. Conversely, central subchondral osteophytes (COs), which are commonly present in human knees with osteoarthritis, have not been reported in horses.
Objectives: To describe and compare computed radiography (CR), single-slice computed tomography (CT), 1.5 Tesla magnetic resonance imaging (MRI), and histological features of COs in equine metacarpophalangeal joints with macroscopic evidence of naturally-occurring osteoarthritis.
Methods: MRI sequences (sagittal spoiled gradient recalled echo [SPGR] with fat saturation, sagittal T2-weighted fast spin echo with fat saturation [T2-FS], dorsal and transverse T1-weighted gradient-recalled echo [GRE], and sagittal T2*-weighted gradient echo with fast imaging employing steady state acquisition [FIESTA]), as well as transverse and reformatted sagittal CT, and 4 computed radiographic (CR) views of 20 paired metacarpophalangeal joints were acquired ex vivo. Following macroscopic evaluation, samples were harvested in predetermined sites of the metacarpal condyle for subsequent histology. The prevalence and detection level of COs was determined for each imaging modality.
Results: Abnormalities consistent with COs were clearly depicted on MRI, using the SPGR sequence, in 7/20 (35%) joints. They were identified as a focal hypointense protuberance from the subchondral plate into the cartilage, at the palmarodistal aspect (n = 7) and/or at the very dorsal aspect (n = 2) of the metacarpal condyle. COs were visible but less obvious in 5 of the 7 joints using FIESTA and reformatted sagittal CT, and were not identifiable on T2-FS, T1-GRE or CR. Microscopically, they consisted of dense bone protruding into the calcified cartilage and disrupting the tidemarks, and they were consistently associated with overlying cartilage defects.
Conclusions: Subchondral osteophytes are a feature of osteoarthritis of equine metacarpophalangeal joints and they may be diagnosed using 1.5 Tesla MRI and CT.
Potential relevance: Central subchondral osteophytes on MRI represent indirect evidence of cartilage damage in horses.