O3255: Outcomes of Treatment of Pediatric Pathologic Femoral Neck Fractures

Background: Pathologic femoral neck fractures pose a challenging clinical problem due to the nature of the
fracture and the compromised bone stock for fixation. Fixation with proximal femoral locking plates (PFLP) may provide improved mechanical fixation in pathologic bone to maintain proximal femoral alignment and reduce the risk of coxa vara. However, their use in femoral neck fractures remains controversial. Limited outcomes literature is available in pathologic femoral neck fractures and suggests a low rate of avascular necrosis (AVN). The purpose of this study is to report outcomes of children with pathologic femoral neck fractures treated with various fixation techniques including PFLP.

Methods: We retrospectively reviewed all surgically treated pathologic femoral neck fractures in patients < 18 years old between 2003-2023. Cases were reviewed for underlying pathology of fracture, fracture location by Delbet Classification, surgical fixation, and reoperation. Radiographs were evaluated for osseous union within 1 year of treatment. Alignment of the proximal femur was assessed radiographically at the time of union by comparing the neck-shaft angle (NSA) and articulotrochanteric distance (ATD) between the affected and unaffected hip. AVN was assessed radiographically at final follow-up using the Ratliff criteria.

Results: 17 patients were identified with mean age at surgery of 9.6 ± 3.7 years (range 4.3-16.8 years) and mean follow-up of 3.8 ± 2.7 years. 2 patients (12%) were female. Pathologies included benign bone cyst (n=13, 76%), fibrous dysplasia (n=3, 18%), and Langerhans cell histiocytosis (n=1, 6%). The distribution of fractures by Delbet classification included 53% Delbet II, 29% Delbet III, and 18% Delbet IV. Surgical fixation was performed with PFLP (76%), flexible intramedullary nails (12%), dynamic hip screw (6%), or Kirschner wires (6%). Radiographically, 14 patients (82%) demonstrated osseous union within 1 year, with 2 (12%) undergoing revisions for nonunion. Within the PFLP group, the rate of union was 73%. No patients developed AVN at final follow-up. Reoperation was performed in 6 (35%) patients: 4/6 (67%) elective removal of hardware or revision of fixation due to growth, and 2/6 (33%) for nonunion. There was no significant difference between the affected and unaffected hip in postoperative mean NSA (133.3 ± 11.4° vs 132.9 ± 10.2°, p = 0.91, respectively) or ATD (15.9 ± 6.2° vs 18.3 ± 5.9°, p = 0.28, respectively).

Conclusion: This is the largest reported series evaluating characteristics and outcomes of children with surgically treated pathologic Delbet I-IV femoral neck fractures. This study provides further evidence of the relatively low risk of AVN in pediatric pathologic femoral neck fractures compared to higher energy traumatic femoral neck fractures. PFLP may be considered to provide stable fixation and maintain proper alignment in compromised bone.