Blount disease (tibia vara) is an angular tibia deformity that includes varus, increased posterior slope, and internal rotation. This deformity was first described in 1922 by Erlacher1 in Germany. In 1937, Walter Blount2 reported on it in the United States. It is the most common cause of pathologic genu varum in adolescence and childhood.
An oblique incomplete closing wedge osteotomy of the proximal tibial metaphysis was described by Wagner3 for the treatment of unicompartmental osteoarthrosis of the knee in adults. Laurencin and colleagues4 applied this technique to the treatment of pediatric tibia vara with favorable results. They spared the medial cortex of the tibia in their incomplete closing wedge osteotomy technique. In each of the 9 cases we treated and describe here, we accidentally completed the tibial osteotomy when attempting the Laurencin technique. Given that the osteotomy was completed, we modified the Laurencin technique by using a 6-hole, 4.5-mm compression plate rather than a 5-hole semitubular plate, and added a large oblique screw from the medial side to compress the osteotomy site and to protect the plate from fracture. In addition, in 2 patients who weighed more than 250 pounds, we used an external fixator for additional stability. In this article, we report the outcomes of correcting adolescent tibia vara with a complete closing wedge tibial osteotomy and an oblique fibular osteotomy.
Materials and Methods
This study was approved by the Institutional Review Board at Pennsylvania State University. Between 2009 and 2012, we performed 9 complete oblique proximal tibial lateral closing wedge osteotomies on 8 patients (2 girls, 6 boys). In each case, the primary diagnosis was Blount disease. One patient also had renal dysplasia and was receiving dialysis. Mean age at time of operation was 15 years (range, 13-17 years). Mean preoperative weight was 215 pounds (range, 119-317 lb). Mean weight gain at follow-up was 4.39 pounds (range, –10 to 19 lb). Mean body mass index (BMI) was 38 (range, 25-48) (Table). All patients had varus angulation of the proximal tibia before surgery. Mean preoperative varus on standing films was 22° (range, 10°-36°). Because of the patients’ size, we used standing long-leg radiographs, on individual cassettes, for each leg.
Surgical Technique
Before surgery, we use paper cutouts to template the osteotomy wedge. We also use perioperative antibiotics and a standard time-out. For visualization of the entire leg for accurate correction, we prepare and drape the entire leg. A sterile tourniquet is used. At the midshaft of the fibula, a 4-cm incision is made, and dissection is carefully carried down to the fibula. Subperiosteal dissection is performed about the fibula, allowing adequate clearance for an oblique osteotomy. The osteotomy removes about 1 cm of fibula, which is to be used as bone graft for the tibial osteotomy. In addition, a lateral compartment fasciotomy is performed to prevent swelling-related complications. The wound is irrigated and injected with bupivacaine and closed in routine fashion.
We then make an inverted hockey-stick incision over the proximal tibia, centered down to the tibial tubercle. After dissecting down to the anterior compartment, we perform a fasciotomy of about 8 cm to accommodate swelling. Subperiosteal dissection is then performed around the proximal tibia. The medial soft tissues are left attached to increase blood supply and healing. During subperiosteal dissection, soft elevators are used to gently retract the lateral soft tissues along with the inferior and posterior structures. We use fluoroscopic imaging to guide the osteotomy as well as screw and plate placement. We use a 6-hole, 4.5-mm compression plate and screws for fixation. The 2 proximal screws of the plate are predrilled in place to allow for application of the plate after completion of the osteotomy. The plate is then rotated out of position on 1 screw, and the osteotomy is identified under fluoroscopy with the appropriate position distal to the second hole of the 6-hole plate.
An oscillating saw and osteotomes are used to perform the oblique osteotomy. The pre-estimated bone wedge is removed. Wedge size is adjusted, if needed. The bone wedge is morselized for bone graft. The osteotomy is then closed, correcting both varus and internal tibial torsion. Our goal is 5° valgus. After correction is obtained, the plate is placed, and the proximal screw is snugly seated. Three cortical screws are placed distally to hold the plate in place under compression mode, and a cancellous screw is placed superiorly at the proximal portion of the plate for additional fixation. The screw placed proximal to the osteotomy site is a fully threaded cortical screw with excellent compression. Correction and proper placement of hardware are verified with fluoroscopy.