The wound is irrigated and injected with bupivacaine. Bone graft is then placed at the osteotomy site. Additional bone graft is placed posteriorly between the osteotomy site and the muscle mass to stimulate additional healing. Another screw is placed obliquely from the medial side across the osteotomy site to provide additional fixation (Figure 1).
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Figure 1. Patient 4—postoperative radiograph.
A deep drain is placed and connected to bulb suction for 24 hours after surgery. The wound is then closed in routine fashion. In 2 patients who weighed more than 250 pounds, we used an external fixator for additional stability (Figure 2).
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Figure 2. Patient 6a—postoperative radiograph.
Postoperative Care
The incisions are dressed with antibiotic ointment and 4×4-in bandages and then wrapped with sterile cotton under-cast padding. The leg is placed into a well-padded cylinder cast with the knee flexed 10°. The leg is aligned to about 5° valgus. The cast is then split on the side and spread to allow for swelling and to prevent compartment syndrome.5 We also use a drain hooked to bulb suction, which is removed 24 hours after surgery. Toe-touch weight-bearing with crutches is allowed immediately after surgery. The cast is removed at 6 weeks, and a hinged range-of-motion knee brace is worn for another 6 weeks. All patients are allowed to resume normal activity after 4 months. In our 2 external-fixator cases, a cast was not used, and toe-touch weight-bearing and knee motion were allowed immediately. The external fixators were removed at about 10 weeks.
Results
Mean postoperative mechanical femoral-tibial angle was 3°, and mean correction was 26° (range, 16°-43°) (Table). Lateral distal femoral angle did not show significant femoral deformity in our sample. Mean medial proximal tibial angle was 74° (range, 63°-79°). In each case, the varus deformity was primarily in the tibia. Mean tourniquet time was 88 minutes (range, 50-119 min). Our complication rate was 11% (1 knee). In our first case, in which we did not use an extra medial screw, the 4.5-mm plate fractured at the osteotomy site 2.5 months after surgery. The 250-pound patient subsequently lost 17° of correction, and valgus alignment was not achieved. Preoperative varus was 25°, and postoperative alignment was 8° varus. This plate fracture led us to use an extra medial screw for additional stability in all subsequent cases and to consider using an external fixator for patients weighing more than 250 pounds. After the first case, there were no other plate fractures. A potential problem with closing wedge osteotomy is shortening, but varus correction restores some length. Mean postoperative leg-length difference was 10 mm (range, 0-16 mm). No patient complained of leg-length difference during the postoperative follow-up.
Eight and a half months after surgery, 1 patient had hardware removed, at the family’s request. No patient experienced perioperative infection or neurovascular damage. Our overall patient population was obese—mean BMI was 38 (range, 25-48), and mean postoperative weight was 219 pounds. Three of our 8 patients were overweight (BMI, 25-30), and 5 were obese (BMI, >30). For prevention of plate failure, we recommend using an extra oblique screw in all patients and considering an external fixator for patients who weigh more than 250 pounds.
Discussion
Correction of adolescent tibia vara can be challenging because of patient obesity. The technique described here—a modification of the technique of Laurencin and colleagues4—is practical and reproducible in this population. The goals in performing osteotomy are to correct the deformity, restore joint alignment, preserve leg length, and prevent recurrent deformity and other complications, such as neurovascular injury, nonunion, and infection.3,6-8 Our technique minimizes the risk for these complications. For example, the fasciotomy provides excellent decompression of the anterior and lateral compartments, minimizing neurovascular ischemia and the risk for compartment syndrome. During cast placement, splitting and spreading reduce the risk for compartment syndrome as well.5
Wagner3,9 demonstrated the utility of a closing wedge proximal tibial osteotomy in adults. Laurencin and colleagues4 showed this technique is effective in correcting tibia vara in a pediatric population. However, they did not specify patient weight and used a small semitubular plate for fixation, and some of their patients had infantile Blount disease. We modified the technique in 3 ways. First, we performed a complete osteotomy. Second, because our patients were adolescents and very large, we used a 6-hole, 4.5-mm compression plate and screws. Third, we used an external fixator for increased stability in patients who weighed more than 250 pounds.