Three dimensional, radiosteriometric analysis (RSA) of equine stifle kinematics and articular surface contact: a cadaveric study.
Authors: Halley S E, Bey M J, Haladik J A, Lavagnino M, Arnoczky S P
Journal: Equine veterinary journal
Summary
# Editorial Summary: Three-Dimensional Analysis of Equine Stifle Movement and Joint Contact Using radiosteriometric analysis (RSA) on cadaveric specimens, Halley and colleagues mapped how the equine stifle's articulating surfaces interact throughout the functional range of motion, addressing a significant gap in our understanding of normal stifle kinematics. The researchers embedded radiopaque markers in the femur and tibia, then captured sequential biplanar radiographs as each joint moved from 110° flexion to full extension, allowing computer-analysed calculation of tibial rotation, mediolateral shift, and pressure distribution across both condyles. The tibia underwent consistent external rotation with extension, whilst moving through an abduction phase (110–135°) followed by adduction toward full extension; critically, the medial compartment's contact area shrank significantly during extension whereas the lateral compartment remained relatively stable, with high-pressure zones shifting cranially on both condyles but more dramatically on the lateral side. These findings have direct clinical relevance for understanding why certain cartilage and meniscal lesions localise preferentially to particular compartments and positions, potentially explaining load concentration during specific phases of the stride or work. For practitioners managing stifle pathology, this biomechanical framework suggests that injury patterns may relate to abnormal kinematics in these specific ranges, and could inform assessment protocols and rehabilitation strategies targeting movement quality through full extension.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding normal stifle kinematics through extension can help identify abnormal movement patterns that may predispose to cartilage and meniscal damage
- •The changing contact patterns through the range of motion suggest that stifle injuries may have location-specific causes related to joint position during loading
- •Knowledge of medial compartment unloading during extension may inform rehabilitation and exercise protocols for stifle pathology management
Key Findings
- •The tibia rotates externally as the stifle extends from 110° to full extension (P < 0.001)
- •Tibial abduction occurs from 110-135° of extension, followed by adduction from 135° to full extension (P < 0.001 and P = 0.009)
- •Medial compartment articular contact area decreases with extension (P = 0.001) while lateral compartment remains unchanged (P = 0.285)
- •Contact centre moves cranially on both condyles with greater displacement laterally; high-contact area increases laterally but decreases medially with extension