Page 4 - RESULTS

Overall goals of achieving length were excellent. Documented preoperative lengthening goals were 6.2 cm (range, 2.5 to 8.0 cm). Radiographically measured lengthening achieved was 5.6 cm (range, 1.7 to 8.0 cm). For the P1 group, the preoperative goal was 6.0 cm (range, 2.5 to 6.5 cm) and final length achieved was 5.2 cm (range, 1.7 to 6.5 cm) (Fig. 5). For the P2 group, the preoperative goal was 6.3 cm (range, 4.0 to 8.0 cm) and the final length achieved was 6.0 cm (range, 2.5 to 8.0 cm) (Fig. 6).

Rate of distraction was calculated as total length gained divided by total number of days of distraction. The overall rate of distraction for the entire group 0.83 mm/d (range, 0.48 to 1.1 mm/d); 0.82 mm/d for P1 and 0.85 mm/d for P2. For femurs alone 0.88 mm/d (range, 0.57 to 1.1 mm/d) and for tibias alone 0.63 mm/d (range, 0.46 to 0.91 mm/d).

RADIOGRAPHIC DATA

The mechanical lateral proximal femoral angle (mLDFA), posterior distal demur angle (PDFA), posterior proximal tibial angle (PPTA), and medial proximal tibial angle (MPTA) were measured before and after lengthening. For femoral lengthening the mean mLDFA before and after are 87.3 degrees (± 1.9 degrees) and 87.6 degrees (± 1.9 degrees), respectively. This difference was not statistically significant (P = 0.06). For femurs the mean PDFA preoperative was 81.1 degrees (± 1.3 degrees) and postoperative 81.0 degrees (± 1.6 degrees). This was not statistically significantly different (P = 0.34). For tibial lengthening, the mean preoperative MPTA was 86.5 degrees (± 1.7 degrees) and after lengthening was 90.0 degrees (± 3.2 degrees). The differences in the MPTA for tibial lengthening were statistically significant (P < 0.01). Finally, the mean PPTA preoperative was 79.7 degrees (± 4.0 degrees) and 78.1 degrees (± 3.6 degrees) after treatment. This difference was not statistically significant (P = 0.09) (Table 2).

COMPLICATIONS

In the P1 group, there were 4 nail breakages in 3 patients (4/58; 7%), occurring in 3 femurs and 1 tibia (Fig. 5). All 4 nail breakages occurred in 3 patients who were admitted to not adhering to weight-bearing restrictions during the consolidation phase. These 3 patients were advised to remain at 50 lb (23 kg) weight-bearing with crutches or a walker until monthly radiographs demonstrated 3 intact cortices.9,17,19 None of these 3 had achieved cortical bridging. All 3 femurs bent into procurvatum and varus deformity. All 3 femurs were treated by fixator-assisted nailing of the femurs. Under general anesthesia, the femur was straightened using 2 uniplanar external fixators (anterior 2 pin monolateral and lateral 2 pin monolateral). The broken PRECICE was removed through the piriformis fossa after the femur was straight. If some parts could not be extracted using long pituitary clamps, they were removed by inserting a retrograde Rush rod to push the distal end of the nail out the proximal end of the femur (Fig. 7). The length and alignment of the femur was maintained by the external fixator, whereas a standard femur locking nail (Trigen; Smith & Nephew, Memphis, TN) was inserted to stabilize the femur. After this nail was locked, the biplanar external fixators were removed, during the same operative procedure. The purpose of the external fixators was as instruments to correct the angular deformities and to maintain the alignment and length during the renailing. All 3 femurs healed without any loss of length and alignment. The fractures occurred during the consolidation phase, on day 175 after surgery in the first patient. The patient was walking unaided up the stairs. The second patient fractured his left femur PRECICE, while walking to bathroom on postoperative day 96. He, too, was walking without crutches. After successfully treating the left femur, he broke the right femur on day 119. In all 3 instances, the nail broke through the weld of the nail that was either at the proximal or distal end of the mechanism. There was 1 fracture of a tibial P1 nail. This was identified at the time of elective nail removal surgery. The patient did not know that the nail had broken as the tibia healed uneventfully with a 5-degree procurvatum diaphyseal bend (Fig. 5). The distal end of the nail was extracted proximally by driving a Rush rod retrograde through the medial malleolus, pushing the distal segment proximally. There was 1 other femur fracture in the P1 group (Fig. 8). This fracture occurred through the anterior-posterior distal locking screw. The fracture occurred quite unexpectedly during a physical therapy straight leg raising hamstring stretch maneuver. The patient was again treated by fixator-assisted nailing. The nail in this case was intact.