A 28-year-old female sustained a fracture of the proximal humerus 8 weeks ago. On clinical examination, the fracture site is non-tender and shows good stability. The patient is progressing well with physiotherapy. To confirm that hard callus formation has occurred and to guide the timing of full weight-bearing and return to sport, which investigation is most appropriate?

Explanation

## Investigation of Choice for Confirming Hard Callus Formation **Key Point:** Plain radiography with multiple views (AP, lateral, and axillary) is the gold standard for confirming hard callus formation and assessing fracture union at 8 weeks post-injury. ### Fracture Healing Timeline and Radiographic Correlation | Week | Phase | Radiographic Feature | Investigation | |------|-------|----------------------|----------------| | 0–2 | Inflammatory | Fracture line, soft tissue swelling | Plain X-ray | | 2–6 | Soft callus | Callus bridging, early mineralization | Plain X-ray | | **6–12** | **Hard callus** | **Dense, mature callus; bridging complete** | **Plain X-ray (GOLD STANDARD)** | | 12 weeks–2 years | Remodeling | Callus resorption, restoration of anatomy | Plain X-ray | **High-Yield:** At 8 weeks, hard callus should be evident on plain radiographs as dense, mineralized bridging callus across the fracture site — the key finding to guide return to activity. ### Why Multiple Views Are Essential 1. **AP view:** Assesses anteroposterior alignment and callus bridging 2. **Lateral view:** Evaluates sagittal plane alignment and callus maturity 3. **Axillary view:** Critical for proximal humerus fractures to assess rotation and tuberosity position **Clinical Pearl:** The presence of bridging callus on at least 3 of 4 cortices on plain radiographs indicates adequate union and is the criterion for progressing rehabilitation and returning to sport. ### Why Plain Radiography Remains Superior - **Cost-effective** and widely available - **Reproducible** and objective assessment of callus maturity - **Radiation dose** is minimal with modern protocols - **Sensitivity and specificity** for hard callus detection are excellent - **Serial comparison** is straightforward with prior films **Mnemonic:** **PLAIN** = **P**rogression, **L**ocal bridging, **A**lignment, **I**ntegrity, **N**o gaps — the five things to assess on radiographs at 8 weeks.