Classifying Ischial Tuberosity Avulsion Fractures by Ossification Stage and Tendon Attachment

Area of Science:

• Orthopedic Surgery
• Pediatric Orthopedics
• Radiology

Background:

• Ischial tuberosity avulsion fractures commonly occur in adolescents.
• Existing classification systems may not fully capture fracture characteristics or predict outcomes.
• A novel approach is needed to classify these injuries based on developmental patterns.

Purpose of the Study:

• To propose and validate a new classification system for ischial tuberosity fractures in adolescents.
• To correlate fracture patterns with skeletal maturity, displacement, size, and tendon involvement.
• To assess the system's ability to predict nonunion rates.

Main Methods:

• Retrospective review of 45 adolescent ischial tuberosity avulsion fractures (2008-2018).
• Classification based on fracture location (Type 1: lateral, Type 2: complete) and pelvic CT-assessed ossification stages.
• Radiographic and advanced imaging (CT/MRI) analysis of fracture characteristics and tendinous insertions.

Main Results:

• Type 1 fractures were associated with younger age, lower skeletal maturity scores, less displacement, and smaller size compared to Type 2.
• Nonunion occurred in 56% of fractures, associated with greater displacement and size.
• Type 2 fractures showed a higher nonunion rate (78%) than Type 1 (33%), though not statistically significant.

Conclusions:

• A new classification system based on ischial tuberosity apophysis ossification patterns is proposed.
• This system correlates with skeletal maturity, fracture characteristics, and involved tendons (semimembranosus, conjoined, adductor magnus).
• The proposed classification may predict nonunion probability in adolescent ischial tuberosity fractures.