Effects of Angled Dynamic Compression Holes in a Tibial Plateau Levelling Osteotomy Plate on Cranially Directed Fragment Displacement.

OBJECTIVE

To compare angled dynamic compression holes in a tibial plateau levelling osteotomy (TPLO) plate to a commercially available TPLO plate in an ovine cadaveric model.

STUDY

DESIGN

Ovine tibias (40 bones) were mounted on a custom-made securement device and radiopaque markers were placed to aid radiographic measurements. A standard TPLO procedure was performed on each tibia with either a custom-made six-hole 3.5 mm angled compression hole plate (APlate) or a six-hole 3.5 mm standard commercial plate (SPlate). Radiographs were obtained before and after tightening of the cortical screws and evaluated by an observer blinded to the plate. Measurements of cranio-caudal displacement (CDisplacement), proximo-distal displacement (PDisplacement) in relation to the long axis of the tibia, and change in tibial plateau angle (TPA) were determined.

RESULTS

CDisplacement was significantly greater in APlate (median 0.85 mm, Q1-Q3: 0.575-1.325 mm) compared to SPlate (median 0.00 mm, Q1-Q3: -0.35-0.50 mm, p < 0.0001). There were no significant differences in the PDisplacement (median 0.55 mm, Q1-Q3: 0.075-1.00 mm, p = 0.5066) or TPA change (median -0.50°, Q1-Q3: -1.225-0.25°, p = 0.1846) between the two plate types.

CONCLUSION

APlate increases cranially directed displacement of the osteotomy in a TPLO procedure without causing TPA change. The reduced interfragmentary distance across the whole osteotomy could improve osteotomy healing compared to standard commercial TPLO plates.