Retrospective Analysis and Characterization of Avascular Necrosis By Bone Location in Pediatric Leukemia/Lymphoma Patients.

Abstract

Background: Avascular necrosis (AVN) is a serious complication of high-dose steroid therapy for pediatric patients with leukemia/lymphoma. AVN affects multiple bones and joints, leading to significant pain in different bone regions, early-onset osteoarthritis, and early joint replacement. Early detection and intervention for AVN may prevent pain and progressive joint collapse. The purpose of this study is to evaluate and characterize the specific AVN locations in a cohort of pediatric and adolescent patients with leukemia/lymphoma using the newly developed Bone Location for AVN from STeroids (BLAST) classification system that considers epiphyseal, metaphyseal, and diaphyseal locations in long bones.

Methods: An imaging database was queried for patients 25 years old and younger with a diagnosis of AVN and leukemia/lymphoma who required steroid treatment. Patient MRIs were reviewed, and AVN sites were classified using the BLAST system. AVN locations were described using descriptive statistics. Multivariable logistic regression analysis was used to assess the odds of AVN bilaterality based on location.

Results: A total of 84 patients (49/35 males/females) with acute lymphoblastic leukemia (ALL) (B-cell 74%, T-cell 21%) or acute myeloid leukemia (5%) were included in this cohort. The median age was 14.8 years at leukemia diagnosis and 16.5 years at AVN diagnosis. Most AVN locations include the femur (87%), tibia (68%), and humerus (25%). On the basis of the BLAST classification, the most common sites of AVN overall include the proximal tibial metaphysis (61%), distal femoral metaphysis (60%) and epiphysis (60%), and femoral head epiphysis (50%). The most common sites of AVN in the tibia, humerus, and femur are proximal tibial metaphysis (89%), humeral head epiphysis (86%), and distal femoral metaphysis (68%) and epiphysis (68%), respectively.

Conclusions: This analysis demonstrates that AVN in leukemia/lymphoma patients on steroid therapy has a clear predilection for specific locations in long bones. Using the BLAST classification, practitioners are better equipped to characterize the location of AVN, monitor high-risk locations for joint collapse, and track early outcomes of preventative treatment. The development of prospective multicenter AVN study groups and screening protocols for early detection will be critical to improve functional outcomes and joint preservation for leukemia/lymphoma survivors and all other patients taking high-dose steroids.

Level of evidence: Level II-retrospective cohort study.