A 6-year-old girl is brought to the orthopedic clinic 3 weeks after a supracondylar fracture of the humerus that was treated with closed reduction and percutaneous pinning. The child now complains of persistent elbow stiffness and limited range of motion. Which investigation is most appropriate to assess for potential myositis ossificans (heterotopic ossification)?

Explanation

## Investigation of Choice for Myositis Ossificans in Supracondylar Fracture ### Clinical Context Myositis ossificans (heterotopic ossification) is a known complication of supracondylar fractures, particularly after surgical intervention (pinning). It typically develops 2–6 weeks post-injury and manifests as progressive stiffness and loss of range of motion. ### Why Plain Radiography is the Investigation of Choice **Key Point:** Plain radiographs are the gold standard for detecting and staging myositis ossificans because they: - Directly visualize heterotopic bone formation - Allow Brooker grading (I–V) for severity assessment - Are readily available and cost-effective - Provide baseline for monitoring progression - Guide prophylactic intervention decisions (indomethacin, radiation) ### Brooker Classification of Myositis Ossificans | Grade | Radiographic Finding | |---|---| | **I** | Isolated bone islands | | **II** | Bone in soft tissues with less than 50% joint involvement | | **III** | Bone in soft tissues with more than 50% joint involvement | | **IV** | Complete ankylosis (fusion across joint) | | **V** | Complete ossification with joint fusion | **High-Yield:** Grades III–V warrant prophylactic intervention (indomethacin 75 mg/day for 6 weeks or single-dose radiation therapy 700 cGy within 72 hours of injury). ### Why Other Investigations Are Not First-Line | Investigation | Limitation | |---|---| | **Ultrasound** | Cannot reliably detect bone formation; soft tissue edema mimics heterotopic ossification | | **MRI with STIR** | Sensitive for edema but NOT specific for ossification; STIR sequences show fluid, not bone | | **Tc-99m bone scan** | Detects metabolic activity but does NOT show mature bone; less specific than plain radiographs | **Clinical Pearl:** MRI is useful for early detection of myositis ossificans (within 2 weeks, before radiographic visibility), but at 3 weeks post-injury, plain radiographs will show mature heterotopic bone clearly. Bone scan shows increased uptake in early myositis but is less specific and does not guide management as well as radiographs. **Mnemonic: BROOK** — **B**one **R**adiographs **O**ssification **O**bservation **K**ey (use plain films to grade myositis ossificans).