However, chemonucleolysis has been tried with substances other than papain such as alcohol and oxygen/ozone, which appear not to cause allergic reactions nor many side-effects. Ozone therapy claims to benefit 80 per cent of cases, although subsequent tests have shown that it fails to reduce the size of the disc in about a third of patients (J Neuroradiol, 2004; 31: 183-9). Alcohol chemonucleolysis has a better record, claiming a success rate of nearly 100 per cent (J Neuroradiol, 2001; 28: 219-29). But neither technique has yet undergone any clinical trials.

The lack of objective trial data is also the problem with electrothermal therapy and artificial hydrogel discs, both of which can only be described as ‘promising’ (Orthopedics, 2002; 25: 767-71).

Trials have been done on cortisone injection - and subsequently led to its being largely abandoned. In a controlled, blinded study of more than 150 patients, cortisone initially showed a slight benefit but, after three months, there was no difference between it and the saltwater placebo. In fact, regardless of treatment, the patients were 17 per cent worse (N Engl J Med, 1997; 336: 1634-40).

Clinical trials of Vax-D traction have been generally positive, with a claimed “success rate” of nearly 70 per cent. It is also alleged to be safe (Neurol Res, 2001; 23: 780-4). However, there have been - albeit rare - reports of a “sudden, severe exacerbation” of pain due to “marked enlargement of the disc protrusion”, requiring emergency surgery, with the device (Mayo Clin Proc, 2003; 78: 1554-6).

More conventional traction, despite being a long-standing technique, has not withstood the scrutiny of clinical trials, which have shown it to be of equivocal effectiveness (J Spinal Disord, 2000; 13: 463-9). In fact, many osteopaths believe traction to be positively harmful, as it may exacerbate any tears in the annulus.

Tony Edwards