1 Principles topenlarge
Anatomic reduction of the articular surface is of paramount importance for successful surgical management and future comfort. Failure to properly reduce the fractures and create friction between the fracture components will load the cortex screws in bending, leading to implant breakage. Failure to reconstruct the articular surface will lead to osteoarthritis and lameness.
Reconstruction of the bony column of the proximal phalanx preserves limb length, promotes load sharing between the bone fragments and implants, and improves comfort.
2 Positioning and approach topenlarge
The horse is positioned in lateral recumbency with the affected limb positioned uppermost.
Direct examination of the proximal portion of the fracture via an
open approach is necessary if the proximal articular surface is significantly comminuted.
If not, the use of radiographic markers for intraoperative radiographic control may be sufficient.
3 Reduction and screw fixation topenlarge
Sequence of reduction
In general, the proximal articular fracture is repaired with cortex screws in lag fashion, taking care to consider screw placement for the plates to follow. After the articular surface is reconstructed and a two-piece fracture created, the transverse fracture is reduced, and the dorsal plate closer to the table is applied first, followed by the uppermost plate. Order of repair is 3 to 1, then 1 to 2 and finally 3 to 2.
Additional dorsal incision
A dorsal midline incision through the skin, subcutaneous tissue and common digital extensor tendon to the dorsal cortex of the proximal phalanx is prepared. The soft tissues are elevated medially and/or laterally to expose the transverse fracture plane.
Next the sagittal fracture is reduced and repaired with 2 screws placed in lag fashion.
4 Double-plate fixation topenlarge
Plate selection and preparation
After the sagittal fracture has been repaired, the transverse fracture is manually reduced and a plate contoured to the dorsal medial aspect of the proximal phalanx. Care is taken to avoid extending the plate beyond the margin of the proximal and distal end of the bone. Typically, a four-hole LCP or LC-DCP plate is used.
Application of the first plate
The plate is applied to the dorsomedial aspect of the bone using cortex and/or locking screws as appropriate. Cortex screws in lag fashion either through the plate or separately may be necessary to reduce and compress any dorsal plane fracture present.
Application of the second plate
The second plate is contoured to the dorsolateral aspect of the proximal phalanx and applied to the bone with cortex or locking screws as appropriate.
Variation: Lag screws through the plate
Depending on the configuration of the transverse fracture, one of the cortex screws in each plate can be inserted obliquely in lag fashion across the transverse fracture to achieve interfragmentary compression and increased stability.