Evaluation of the healing process in fractures using early and delayed bone scanning.

Fifty-two fracture sites were evaluated by bone scintigraphy after acquiring similar views of the lesions at 4 and 24 h following technetium-99m methylene diphosphonate administration. After calculating 24/4 h radio-uptake ratio (RUR) and using 1.15 as the critical point of separation, fresh healing lesions could be separated from old healed fractures persisting as 'hot spots' with a sensitivity of 100% and specificity of 82%. The 24/4 h RUR technique is a new approach in measuring the osteoblastic activity at the lesion site. The technique appears to have clinical significance in the detection and follow up of the healing status of occult fractures where radiological procedures are of limited value.