Page 5 - COMPLICATIONS CONTINUED

There were 3 P1 femur nails that began distracting the bone and then failed to continue to lengthen (3/58; 5%). One of these patients presented as a premature consolidation. Two of these were treated with nail exchange and reosteotomy. In the third, the lengthening was stopped 1 cm short of the goal. This patient was planning to have a bilateral tibial lengthening performed at a later date, so the leg length difference was equalized during the second lengthening and height goals were achieved. Two tibias in 1 patient and 1 femur in another had delayed ossification and required with delayed weight-bearing and compression-distraction by the bidirectional nail mechanism (accordion maneuver; 0.5mm distraction followed 4 h later by 0.5mm compression, the cycle of which was repeated 2 to 3 times a day for a month or more). There was 1 deep vein thrombosis in a patient who stopped anticoagulation before full weight-bearing. Our protocol is to stop anticoagulation once a patient is approved to ambulate without device support. In the P1 group, there were no symptomatic fat embolisms, infections, or compartment syndromes (Table 3). In the P1 group, there was 1 patient who underwent bilateral femoral and tibial PRECICE nail lengthening simultaneously. He did not have any evidence of fat embolism, despite all 4 nails being inserted during the same surgery. The other 3 P1 patients that underwent bilateral femoral and tibial lengthening had each bilateral procedure performed at different times. None experienced fat embolism problems.

In the P2 group, there were 2 minor screw complications (2/58, 3%), both in tibial cases. One case had an inadvertent miss to the distal locking screws that was not seen until postoperative follow-up. Another case had a proximal tibiofibular locking screw back out and become prominent under the skin. In the first case, the 2 screws had sufficiently locked the nail that it lengthened without a problem. The tibia was redrilled and the locking screws inserted through the locking holes of the tibial nail at the surgery as the staged bilateral femoral lengthening surgery, which took place 3 weeks after the bilateral tibial lengthening surgery. In the backed-out screw case, a threaded locking screw was used instead of the smooth peg-like PRECICE screws.

One P2 patient developed bilateral peroneal nerve partial paresis due to a stretch injury that occurred during the surgery. This patient had a very positive preoperative popliteal angle, which we elected to treat by hamstring muscle recessions. It is presumed that the straight leg raising maneuver to check the popliteal angle after the muscle recession, while the patient was still under general anesthesia, led to the stretch injury. This was treated by bilateral peroneal nerve decompression 3 days after surgery.20 Lengthening continued at a rate of 0.75 mm/d and the goal of lengthening was achieved. Both nerves gradually fully recovered both motor and sensory function despite lengthening.

In our P2 group, there was 1 nail breakage during late consolidation (Fig. 7). The nail silently bent into varus and produced a noticeable bump on the lateral side of the thigh. The patient continued to walk without pain and complained only about a thigh bump. This patient had disregarded the weight-bearing restrictions that were reinforced in writing to him each time he sent a follow-up radiograph during the consolidation phase. He too had stopped using crutches without being released to do so. He was treated by the fixatorassisted technique, but required an osteotomy of the already malunited (varus) femur. A single frontal plane, lateral external fixator was applied to correct the varus deformity. After removal of the proximal nail segment, a percutaneous osteotomy was performed through the apex of the bend. Once the femur was aligned by the fixator, the distal nail segment was pushed proximally through the piriformis fossa by means of a retrograde Rush rod. The femur was then fixed with a locked intramedullary nail and the external fixator removed.

In the P2 group, there were no failures of the mechanism to distract and no premature consolidation. There were also no infections or compartment syndromes (Table 3). Two patients who underwent bilateral femoral P2 nail insertion were diagnosed with suspected fat embolism syndrome manifesting as low pulse oxymeter readings from the first postoperative day. This was associated with shortness of breath in 1 patient and mild mentation changes in both. The condition resolved after 1 day in 1 patient, but 4 days of additional hospitalization were required (usual hospitalization is 3 to 4 d) by the other patient whose right lung showed significant opacification on both chest x-ray and computerized tomography. There was no evidence in either patient of venous embolism on computerized tomography scan; neither was there evidence of aspiration or pneumonia in either case. The presumptive diagnosis of fat embolism was made after ruling out all other possible causes. Both patients had the medullary canal vented according to the multiple drill holes at the planned osteotomy level, as described above. Both recovered with only nasal prong oxygen treatments and neither required intensive care unit admission. As cited previously, none of the 4 patients who underwent bilateral femoral and tibial lengthenings experienced fat embolism problems.

In total there were 7 implant failure complications in the P1 group (7/58; 12.1%) and only 1 implant failure complication in the P2 group (1/58; 1.7%). This difference was statistically significant between the groups (P = 0.02).