Dysbaric Osteonecrosis: Prevention

Early recompression of experimental limb bends in sheep prevents progression to DON, and this validates the clinical practice of recompression of all cases of DCS to reduce long-term damage.

Early recognition is imperative, and the following investigations are recommended for all professional divers exposed to frequent hyperbaric conditions at depths greater than 15 metres.

  1. Baseline long bone x-ray studies.
  2. MRI examination in doubtful plain x-ray findings or to define extent of lesions.
  3. MRI 3 months after an episode of DCS involving the hips or shoulders.

Image-guided biopsy of suspicious lesions (or even surgical biopsy) may be appropriate in special circumstances.

The disease is rare in recreational scuba divers who follow decompression tables and use only compressed air to depths less than 50 metres. For these groups, unless there is a specific cause for concern, serial radiological investigation is certainly not warranted because of the unnecessary irradiation hazards and expense.

The problem of what to do when confronted with an asymptomatic B lesion is not yet clear. If the B lesion is thought to be provoked by non-adherence to established diving tables, these should clearly be followed in the future. Under these conditions, it is assumed that the B lesion is induced because of excessive provocation. If the diver has adhered to normal decompression tables, then it is presumed that he or she is particularly predisposed to DON, and consideration is given to restricting diving to reduce the risk of further lesions. It is generally accepted that the need for formal decompression staging should be avoided, as should experimental or helium diving. Doubtful cases should be treated as if positive until further radiological assessment clarifies the issue.

If a juxta-articular lesion is present, traditional teaching suggests that all exposure to compression should cease. There is, however, no evidence that this modifies the subsequent course of the problem. Today, a pragmatic approach is more common, with close attention given to the functional capacity of the individual diver along with counselling about avoiding further provocative diving if possible. Annual assessment of these divers will pay close attention to their continued functional capacity.