Ex vivo equine medial tibial plateau contact pressure with an intact medial femoral condyle, with a medial femoral condylar defect, and after placement of a transcondylar screw through the condylar defect.
Authors: Bonilla Alvaro G, Williams Jarred M, Litsky Alan S, Santschi Elizabeth M
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Osteochondral defects of the equine medial femoral condyle (MFC) represent a significant clinical challenge, yet little is known about how they alter load distribution across the stifle joint or whether surgical fixation restores normal biomechanics. Bonilla and colleagues used pressure-sensing technology to map contact forces on the medial tibial plateau in six cadaveric equine stifles under three conditions—an intact MFC, an MFC with a 15 mm osteochondral defect, and the same defect stabilised with a transcondylar lag screw—whilst applying 1800 N axial load at three angles of flexion (130°, 145°, and 155°). The defect alone significantly reduced force transmission and contact area at certain flexion angles and caused pressure to shift abnormally caudally and abaxially during flexion; insertion of the transcondylar screw partially restored force loading at 130° of flexion but did not fully normalise the altered pressure distribution patterns created by the defect. These findings suggest that whilst transcondylar screw fixation may provide some biomechanical benefit in reversing load deficits, it may not completely restore the natural articular cartilage contact patterns, implying that defect size, healing, or post-operative rehabilitation protocols warrant careful consideration in clinical cases. Understanding these pressure dynamics could help inform decisions about surgical intervention, weight-bearing protocols, and long-term prognosis in horses with medial femoral condylar osteochondral lesions.
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Practical Takeaways
- •Transcondylar screws may partially restore joint mechanics in horses with medial femoral condylar lesions, but do not fully normalize pressure distribution patterns that could predispose to osteoarthritis
- •The degree of improvement with screw fixation appears angle-dependent, suggesting surgical outcomes may vary with post-operative stifle range of motion
- •This research provides biomechanical rationale for transcondylar screw use in equine stifle surgery, though long-term clinical outcomes should guide surgical decision-making
Key Findings
- •MFC osteochondral defects significantly reduced force and contact area on the medial tibial plateau, particularly at 145° flexion
- •Transcondylar screw placement restored force values to intact levels at 130° flexion but reduced overall contact area in extension
- •Stifle flexion increased force, contact area, and stress load on the medial tibial plateau across all conditions, with greatest effects caudally
- •MFC defects altered pressure distribution patterns caudally and abaxially during flexion, changes not reversed by screw fixation