- accetable reduction:
- more than 50% of cortical overlap;
- > 10 deg of angulation in any plane is unacceptable
- < 5 deg of varus or valgus;
- < 10 deg of anterior or posterior angulation;
- < 10 deg of rotation;
- < 1 cm for leg length discrepancy;
- no distraction is tolerated;
- 5 mm of distraction may increase healing time to 8-12 months;
- indications for operative correction:
- valgus deformity of more than 10-12 deg;
- varus deformity of more than 6-10 deg;
- external rotation deformity more than 15-20 deg;
- internal rotation deformity of more than 10-15 deg;
- shortening of more than 2 cm;
- posterolateral approach for osteotomy and grafting be attentive to the safe zones;
- prevention of neurovascular injury:
- have somatosensory evoked potentials available if significant angulatory deformity is to be corrected;
- consider application of sterile pulse oximeter to great toe - which allows monitoring of pulses during osteotomy;
- for varus/valgus deformity the osteotomy cut should be made in the coronal plane, where as anterior/posterior angulatory deformities should be managed w/ an osteotomy cut in the saggital plane;
- consider use of femoral distractor w/ 6.0 mm half pins placed parallel to the joint surfaces of the tibial plateau and plafond;
- the distractor can then be used to align the half pins so that they are parallel (thus aligning the malunion);
- following operative correction of the malalignment, recheck the ROM of the ankle joint and consider the need for Achilles tendon lengthening
Oblique osteotomy for the correction of tibial malunion.
Treatment of tibial malunions and nonunions with reamed intramedullary nails.
Effects of tibial malalignment on the knee and ankle.
No arthrosis of the ankle 20 years after malaligned tibial-shaft fracture.
Long term effects of tibial angulatory malunion on the knee and ankle joints.
Osteotomy Planning Using the Anatomic Method: A Simple Method for Lower Extremity Deformity Analysis
The CORA-Centric method places the fixator hinge directly over the CORA, minimizing unintended translation The CORA-Perpendicular application places the fixator hinge on the bisector of the deformity. Placement on the convex side of the deformity will produce lengthening while placement on the concave side of the deformity will produce shortening. This application should be employed when such lengthening or shortening is desired. The placement of the hinge on the concave or convex sides of the deformity will cause shortening or lengthening, respectively. The placement of the hinge proximal or distal to the bisector line will cause lateral translation. This application should be used when the hinge cannot be placed directly over or perpendicular (on the bisector) to the CORA. The surgeon must calculate that the unintended translation can be corrected by the angulation and translation screws.