Proper imaging is necessary for the accurate quantification of bone bridges to determine resectability and to identify the best surgical approach to resection. MRI with software for the generation of 3-D physeal maps is a reproducible method with good interobserver reliability.22,23 Intraoperative computer-assisted imaging also is beneficial for determining the extent and location of the resection to ensure complete bone bridge removal.24
To our knowledge, a direct approach through parapatellar arthrotomy for the resection of a centrally located distal femoral physeal bone bridge has not been previously described. This novel technique provided direct access to the physeal bone bridge and was performed without injuring the adjacent physeal cartilage in the medial and lateral columns of the distal femur, which may grow normally in the absence of the bridge. Instead of using a lateral or medial approach with a metaphyseal window,4 we directly approached this central bar through a parapatellar approach and were able to completely resect it under direct visualization. This obviated the need for an arthroscope or dental mirror. To remove the entire physeal bone bridge, we needed to resect completely from the anterior cortex to the posterior cortex. Although this technique potentially increased the risk of iatrogenic fracture, we believed that this risk would not differ greatly from that of disrupting the medial or lateral metaphysis and would be more stable with either axial and torsion load. At 3-year follow-up, the patient exhibited restored normal growth in his operative limb relative to that in his nonoperative limb, had not developed angular deformity, and had maintained his previously developed limb-length discrepancy that could be corrected with the epiphysiodesis of his opposite limb at a later date.
The limitations to this technique include the fact that it may be most effective with small-to moderate-sized central physeal bone bridges, although resection has shown good results with up to 70% physeal involvement.8 In this patient, the bone bridge was moderately sized (30% of the physis), centrally located, and clearly visible on fluoroscopy. These characteristics increased the technical safety and ease of the procedure. The resection of large, peripheral bridges may destabilize the distal femur. The destabilization of the distal femur, in turn, can lead to fracture. Patellofemoral mechanics may also be affected during the treatment of distal femoral physeal bone bridges. This patient has not experienced any patellofemoral dysfunction or symptoms. Given the patient’s age and significant amount of remaining growth, he will need close monitoring until he reaches skeletal maturity.
This paper will be judged for the Resident Writer’s Award.