A 28-year-old female sustained a fracture of the distal radius 3 weeks ago. She complains of persistent pain and swelling at the fracture site. On examination, there is mild tenderness and some crepitus. The treating surgeon wants to assess whether soft callus formation has begun and to monitor the early stages of fracture healing before allowing mobilization.

## Investigation of Choice for Assessing Early Fracture Healing (Soft Callus Stage) ### Why Plain Radiography is the First-Line Investigation **Key Point:** Plain radiography (posteroanterior and lateral views) is the standard first-line investigation for monitoring fracture healing at all stages, including the soft callus stage at 2–3 weeks. It is readily available, cost-effective, and provides sufficient structural detail to assess callus formation and fracture alignment. **High-Yield:** At 3 weeks post-fracture, soft callus is typically becoming radiographically visible on plain films in uncomplicated fractures. Plain radiography allows the surgeon to assess bridging callus, fracture alignment, and early signs of union before permitting mobilization. This is the routine clinical approach as recommended in standard orthopedic practice (Rockwood & Green's Fractures in Adults). ### Timeline of Radiological Visibility in Fracture Healing | Investigation | Inflammatory Stage (0–3 days) | Soft Callus (2–3 weeks) | Hard Callus (3–8 weeks) | Remodeling (8 weeks+) | |---|---|---|---|---| | **Plain Radiography** | Fracture line visible | **Soft callus becoming visible** | Bridging callus clearly visible | Progressive mineralization | | **Radioisotope Scan** | Positive (24–48 hrs) | Peak uptake | Moderate uptake | Decreasing uptake | | **MRI** | Marrow edema visible | Soft tissue callus visible | Can assess union | Remodeling phase | | **CT Scan** | Fracture line clear | Early callus may be seen | Hard callus clear | Detailed remodeling | **Clinical Pearl:** Plain radiography is the **investigation of choice for routine monitoring** of fracture healing at all stages. Radioisotope bone scan (Tc-99m) is more sensitive for detecting early osteoblastic activity but is reserved for specific indications such as suspected stress fractures, occult fractures, or suspected delayed union/non-union — not for routine early healing assessment. ### Why Other Investigations Are Less Appropriate in This Context - **Radioisotope Bone Scan (Tc-99m):** While highly sensitive for metabolic bone activity and positive as early as 24–48 hours, it is not the investigation of choice for routine fracture healing monitoring. It is reserved for suspected non-union, occult fractures, or when plain films are inconclusive. It is less specific and involves radiation exposure. - **MRI:** Excellent for soft tissue and marrow edema assessment, but not the routine first-line investigation for monitoring fracture healing. Reserved for complications or soft tissue injury assessment. - **CT Scan:** Provides excellent bony detail and is useful for complex fractures or when plain radiographs are inconclusive, but is not required for routine early healing assessment due to higher radiation dose and cost. ### Clinical Application Plain radiography is the standard of care for: - Initial fracture assessment and classification - Monitoring fracture healing at all stages (2–3 weeks, 6 weeks, 3 months) - Assessing fracture alignment and callus formation before mobilization - Identifying complications such as malunion or non-union [cite: Rockwood & Green's Fractures in Adults, 8th Ed., Ch. 1; Miller's Review of Orthopaedics, 7th Ed.]