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Editor, – I refer to the article on sleep studies (Aust Prescr 1998;21:40-3). One of my patients is a 40-year-old man with diagnosed sleep apnoea, but on no treatment. He has an undisplaced distal radial fracture involving the joint surface, diagnosed on bone scan. He had symptoms 12 months post-fracture and a positive bone scan 6 months post-injury. I understand that a bone scan can remain positive for some time post-fracture and is often a sign of healing. However, if his continuing symptoms are attributable to delayed healing, is sleep apnoea implicated and, as a follow-on, would treatment of the sleep apnoea assist the recovery?
J. Azoury
General Practitioner
Queanbeyan, N.S.W.
Dr A.M. Southcott, the author of the article, comments:
Dr Azoury raises a very interesting question about sleep apnoea and delayed fracture healing. Whilst I was unable to find any direct references linking these two topics, there are some tantalising pieces of information which could lead one to speculate on such a relationship. The first is the anabolic response induced by growth hormone release from the pituitary gland, and the beneficial effects of growth hormone administration in patients after surgery and trauma.1 The second is the increasing awareness of the metabolic aspects of sleep apnoea. In patients with severe sleep apnoea, levels of insulin-like growth factor-1,a biological marker of growth hormone secretion, are reduced as are nocturnal levels of growth hormone.2 Some patients with severe sleep apnoea have levels similar to patients with growth hormone deficiency which may have effects on bone and mineral metabolism and body composition. It is thought that repetitive arousal due to sleep apnoea may impair the growth hormone response to endogenous bursts of growth hormone releasing hormone. Treatment of severe sleep apnoea results in increased secretion of growth hormone3 and an increase in insulin-like growth factor-1 levels.4
It would be possible to speculate that in untreated severe sleep apnoea, fracture healing may be compromised due to a relative deficiency of growth hormone. As mentioned above, to my knowledge this has not been proven.
