Bone scanning.

This article outlines the physical and biological bases of bone scanning and then describes the essential features of the technique. The principles underlying the clinical applications are listed, followed by a brief introduction to interpretation of the scan images.     

Bone cancer risk estimates.

Due to confusion between endosteal (bone surface) dose and average skeletal dose, ICRP 60 has substantially overestimated the risk of radiogenic bone cancer. This confusion apparently stems from an incorrect reading of the BEIR IV report, which does not clearly draw this distinction. It should also be noted that what appear to be summary numerical risk estimates for bone sarcoma induction in BEIR IV and BEIR V refer only to average skeletal dose as calculated for 224Ra.     

Bone tumors in thorotrast patients.

Among the Thorotrast patients throughout the world, nine bone sarcomas (six histologically confirmed and three possible) were reported as of 1974. Their appearance times ranged from 16 to 33 years, averaging 26 years after Thorotrast injection. In some countries the population at risk is uncertain, but in Denmark, Germany, and Portugal, about 3000 patients have been followed more than 10 years (45,000 persons · years at risk beyond the first 10 years). In these 3000 patients, three to six bone sarcomas have occurred, compared with 0.5 case expected naturally. Using the dosimetric results of Rowland and Rundo and assuming that translocating²²⁴Ra was mainly responsible, the provisional risk coefficient is 55 to 120 bone sarcomas/10⁶ person · rad of average dose to the skeleton without marrow. This risk coefficient is highly tentative because it is based on only three to six bone sarcomas, all reported since 1972. If additional bone sarcomas occur among the living Thorotrast patients, the risk coefficient could increase appreciably. For comparison, the risk coefficient for long protracted injections of²²⁴Ra is about 200 bone sarcomas/10⁶ person · rad, based on 54 cases of bone sarcoma.     

Waiting lists. Bone of contention

The number of orthopaedic consultants has increased by 78 per cent since 1984, but average waiting time has hardly changed. Orthopaedics is one of the greatest problem areas for waiting lists although workloads have fallen by about a fifth in the past five years. An extra 85,000 orthopaedic patients will have to be admitted over the next five years if the government is to eliminate waits of more than six months. Consultants oppose the expansion of the staff grades. Specialist centres may have to be established to deal with the backlog.     

Bone maintenance: implant versus transplant.

Bone maintenance based on various attachment mechanisms is the key to tooth-root replacement safety and efficacy. The dental implant has broad applicability based on design, but demonstrates progressive peri-implant bone loss. The allogeneic tooth transplant, significantly less applicable because of size, is antigenic and rejected by bone-replacement root resorption. Since the predictability and survival times of these implant and transplant modalities are similar and there is less residual bone loss with the transplant, it is suggested that for clinical situations such as the fresh extraction socket, where there is room, the allotransplant, rather than implant, is the root-replacement of choice.     

Bone scan appearances after uncemented hip replacement.

Persistent increased uptake on a technetium bone scan after a cemented hip replacement usually indicates pathology, either loosening or infection. The natural history of scan appearances in uncemented replacements is different and can be predicted from a plain X-ray. The diagnostic value of a bone scan is therefore questionable when investigating pain after uncemented hip replacement.