Varus-Producing Lateral Distal Femoral Opening-Wedge Osteotomy

Abstract

Valgus knee alignment in excess of physiological valgus leads to excessive loading of the lateral compartment, which can potentially increase the risk of osteoarthritis and can place the medial knee structures at risk of chronic attenuation. Varus-producing distal femoral osteotomies have been proposed for correction of valgus malalignment, to relieve tension on medial-sided structures, as well as to off-load the lateral compartment. Understanding that symptomatic valgus deformity of the knee represents a complex problem that is magnified in the setting of lateral compartment arthritis or medial ligamentous incompetence, we present our preferred technique for a varus-producing distal femoral osteotomy using plate osteosynthesis and cancellous bone allograft.

Fig 1

Standing anteroposterior alignment film of the bilateral lower extremities. A line drawn from the center of the femoral head to the center of the talar dome reveals medial translation of the mechanical axis, consistent with valgus malalignment of both knees. (“det” is a computer-generated mark and has no meaning.)

Fig 2

Methodology by which varus correction can be made using preoperative radiographs. The angle of correction is determined by an angle created by the crossing of lines drawn through the anatomic axes of the femur and of the tibia. This angle is then transposed to the lateral aspect of the femur. Of note, 1 cm of the medial cortex should be left intact while the surgeon is performing the osteotomy to avoid medial cortex fracture. (AT, adductor tubercle.)

Fig 3

Intraoperative photograph of a right lower extremity with the patient in the supine position showing dissection of the subcutaneous tissues to the level of the iliotibial band. This structure is then incised along the length of its fibers to reveal the underlying vastus lateralis muscle.

Fig 4

Intraoperative photograph of a right lower extremity showing placement of guide pins in the lateral femoral cortex and the assembled osteotomy guide over these pins to guide the distal femoral osteotomy. (IT, iliotibial.)

Fig 5

Intraoperative photograph of a right lower extremity with the patient in the supine position. A reciprocating saw is placed within the osteotomy guide to begin the distal femoral osteotomy on the right lower extremity. As shown in this image, care is taken to protect the surrounding soft tissues.

Fig 6

Intraoperative fluoroscopic image of a right knee showing the beginning of a distal femoral osteotomy through the lateral cortex of the femur with advancement of a osteotome within the bone, leaving the medial cortex intact.

Fig 7

Intraoperative (A) and fluoroscopic (B) images of proper placement and expansion of a blunt spreading device within the previously created defect in the lateral cortex of the right distal femur with the patient in the supine position on the radiolucent bed.

Fig 8

Intraoperative image showing the appropriate technique for contouring the distal femoral plate for placement on the lateral aspect of the distal femur. (DFO, distal femoral osteotomy.)

Fig 9

Expansion of the distal femoral cortical defect in a right femur with a single tine to allow for ease of placement of the distal femoral plate (with patient in supine position).

Fig 10

Right lateral distal femur in a supine patient with the final construct secured in place with adjunctive bone allograft within the void created by the osteotomy.

Fig 11

Final fluoroscopic (A) and intraoperative (B) images of a right knee and distal femur showing appropriately placed fixation with the desired amount of correction. (C) Postoperative lateral radiograph showing plate placement and bone healing. (DFO, distal femoral osteotomy.)