This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Orthopaedics
Heterotopic ossification is a condition in which there is deposition of bone around the joints. Which of the following parameters is the most useful for this condition - 
Select and explain. 
A. Serum calcium, B. Serum phosphate, C. Serum alkaline phosphatase, D. Serum PTH
C: Serum alkaline phosphatase
Answer: C: Serum alkaline phosphatase 
Explanation: Bone scan ( Tc 99 three phase scan) is the most sensitive for early detection of heterotropic ossification. ALKALINE PHOSPHATASE and 24hr PGE2 are screening tests for heterotropic ossification. REF:Essential ohopaedics- Maheshwari- 5th edn - pg no 53.