Symptoms associated with lysis of the pars interarticularis

Comparisons were made between the symptoms of 131 patients with lysis of the pars interarticularis and 2229 patients without lysis, attending a first referral back pain clinic. The canal diameter measured by ultrasound was compared in the two groups, and the slip ratio measured for those with olisthesis. There were significantly fewer patients who had symptoms associated with disc prolapse and lysis of the pars. It is suggested that an enlarged central spinal canal may protect the patient with a pars defect from disabling root problems in the presence of a disc lesion. The most common symptom in those attending with lytic defects was pain in the back and/or referred pain, occurring with nearly twice the frequency for other attenders at the clinic. The incidence of lysis (5.6%) in patients attending the clinic was probably no greater than its incidence in the general population.