Management depends on the stage at which the fracture is diagnosed and the degree of varus deformity.
Intraoperative diagnosis
Several reports suggest that if the fracture is diagnosed during the operation it should be reduced and internally fixed. Thereafter, the UKA can be completed in the expectation of a good result (Berger et al, 2005). If the medial fragment is comminuted, it is best fixed with a medial buttress plate. The alternative option is to use cancellous screws inserted through the medial fragment under image intensifier control.
Figure 11.5 Tibial plateau fracture fixed with a buttress plate. : (a) post operation; (b) fracture; (c) post fracture.
Postoperative diagnosis
The following algorithm is suggested but may need to be modified according to the circumstances.
Within three months of surgery:
A. If the fracture is minimally displaced, or undisplaced, employ external splinting to maintain alignment while awaiting union.
B. If there is significant displacement, employ open reduction and internal fixation with an AO buttress plate or interfragmentary screws (Fig. 11.5).
Later than three months after surgery:
A. If the fracture is united and the varus deformity is acceptable, no action is required.
B. If the fracture is united but causing pain, suspect tibial component loosening. If this is confirmed, revise to a TKA.
C. If the fracture is not united, revise to a TKA with a stemmed tibial component.
What constitutes ‘acceptable’ varus deformity? In this context, up to 5° of varus is probably acceptable. In UKA, varus malalignment does not have the same sinister implication as it has in TKA; indeed, many practitioners aim always to leave the operated limb in a few degrees of varus.
