Can an anomalous lumbo-sacral or lumbo-iliac articulation cause low back pain? A retrospective study of 12 cases.

Unlabelled: Although anomalous lumbo-sacral articulations are present in 5 to 7% of the population at large, their clinical relevance remains a matter of debate. Articulation between the L5 transverse process and the sacrum or ilium has been implicated as a cause of low back pain.

Objective: To define symptoms and effects of steroid injections in patients with an articulation between a L5 transverse process and the sacrum or ilium.

Patients And Methods: Patients with low back pain and an expanded L5 transverse process articulating with the sacrum or ilium were studied retrospectively. Patients with an expanded transverse process that did not articulate with the sacrum or ilium were excluded. Demographic data, symptoms, physical findings and results of investigations were recorded. Efficacy of steroid injections into the anomalous articulation performed under fluoroscopic monitoring was evaluated in the short, medium and long term.

Results: Twelve patients (seven men and five women) with a mean age of 41.1 years (17-90 years) and a mean time since symptom onset of 1.9 years (0.2-4 years) were studied. All 12 patients reported pain on the side of the anomalous articulation (left, n = 10), either in the low back (n = 6) or in the buttock (n = 6). Eight patients had pain radiation to all (n = 1) or part (n = 7) of the lower limb on the same side. One patient had mild motor loss (4/5) and another had paresthesia in the foot. Radiographs were obtained in all 12 patients, computed tomography in six, magnetic resonance imaging in two, myelography in two, a bone scan in two and an electromyogram in one. Three of the 11 patients treated by steroid injection experienced pain during the procedure. Ten patients were improved in the short term and nine reported a 50% decrease in their pain after one month. Of the eight patients who were reevaluated after six to 24 months, seven were improved or free of symptoms and one was unchanged.

Conclusion: An anomalous transitional articulation should be considered as a possible factor in the genesis of low back pain in patients who do not have the degenerative lesions classically responsible for this symptom. Local steroid injections should be tried before surgery is considered.