In vitro biomechanical evaluation of four surgical techniques for fusion of equine centrodistal and tarsometatarsal joints.

The research article examines the biomechanical properties of four different surgical techniques used for the fusion of two joints in horses. The study concludes that, while all methods have certain strengths, surgical drilling may decrease joint stability, while techniques such as dorsomedially applied locking compression plate (DMLCP) and a single large, dorsally applied kerf-cut cylinder (DKC) could potentially enhance stability.

Research Methodology

• The study worked with 24 sets of paired tarsi (angled joint in the hind limb of quadrupedal mammals) gathered from horse cadavers.
• The tarsi used did not have substantial signs of osteoarthritis.
• Four different methods were used on one tarsus from each pair to simulate surgical fusion techniques. These included surgical drilling, two medially to laterally placed kerf-cut cylinders (MLKCs), a single large dorsally applied kerf-cut cylinder (DKC), and a dorsomedially applied locking compression plate (DMLCP).
• The contralateral control tarsi were evaluated against these test constructs.
• Constructs and control tarsi were evaluated in four-point bending in the dorsoplantar, lateromedial, and mediolateral directions.
• Internal and external rotation and axial compression were evaluated.
• The bending, torsional, and axial stiffness values were calculated.

Study Findings

• The results showed clear variations in performance based on the surgical technique used.
• Exposed to all biomechanical testing, surgical drilling significantly reduced joint stability, compared with the control tarsi (taking no action).
• The MLKC constructs outperformed the control tarsi in four-point bending, but underperformed in external and internal rotation.
• The DMLCP and DKC constructs had superior stiffness in the dorsoplantar, rotational, and axial compression directions only, as compared to the control tarsi.
• The DMLCP constructs did not perform well in lateromedial or mediolateral directions.
• Quite interestingly, the DKC constructs were the only group to demonstrate higher stiffness in the mediolateral direction as compared to the control tarsi.

Concluding Remarks

• The results suggest that a surgical drilling approach to joint fusion might reduce the stability of the tarsal joint in horses that do not suffer from clinical osteoarthritis.
• However, the DMLCP and DKC approaches are able to significantly enhance the stability as compared to the control, making them, potentially, superior techniques.