Introduction: Age related histological and radiological changes are widespread in the lumbar spine. The correlation with symptoms is poor and there is good evidence that in later decades the incidence of back symptoms decreases, despite the relentless progression of radiological abnormalities. Much confusion exists regarding Accident Compensation Corporation (ACC) insurance entitlement following injuries in the presence of asymptomatic but existing radiological ageing changes (spondylosis) and existing but asymptomatic spondylolysis/isthmic spondylolisthesis.

Aim: To review the relevant literature and ACC Acts to clarify the ACC Act definition of injury/accident and exclusion criteria and the natural history of spondylosis/spondylolysis/spondylolisthesis, in relation to patients sustaining new lumbar spine injuries in the presence of existing but asymptomatic radiological abnormalities.

Method: The relevant literature and legislation (1992 ARCI and 1998 AI Acts) were reviewed.

Results: Regarding spondylolysis and low grade isthmic spondylolisthesis the literature is conflicting in relation to the incidence of back symptoms. The ACC Acts do not discuss existing disorders or degenerative conditions, but focus on exclusion of cover for ‘personal injury caused wholly or substantially by the ageing process’.

Conclusions: As with clinical decision making medico-legal assessment requires a meticulous history as the primary focus. It is inappropriate to apportion undue weight to radiological abnormalities that correlate poorly with symptoms.