TECHNIQUE OF FACET JOINT INJECTIONS – A PROSPECTIVE RANDOMISED CONTROLLED TRIAL

Abstract

Introduction Local steroid injection is commonly performed as a treatment for facet joint arthritis in the lumbosacral spine. The injection is performed under image guidance for which some surgeons utilise antero-posterior (A-P) imaging only while others prefer oblique imaging.

Purpose The aim of this study is to find out the difference in the functional outcome in patients who received the facet joint steroid injection by A-P imaging and those who had the injection by oblique imaging.

Material and Methods A prospective randomised controlled trial was performed by randomly allocating the 20 patients who were diagnosed to have facet joint arthritis clinically and by magnetic reasonance image scans, and who were then placed in the list for facet joint injections. Ten patients in Group I received the facet joint injections with A-P imaging while 10 patients in Group II received the facet joint injections with oblique imaging using image intensifier. All the patients received 40mg of methylprednisolone acetate with 1mL of 1% lignocaine and 1mL of 0.5% bupivacaine to each joint. The duration of the entire procedure was noted. Short Form-36 (SF-36) questionnaire was used before the procedure and at six weeks after the procedure to assess the functional outcome.

Results All the patients were followed up for a period of six weeks. The mean age was 51.3 yrs in Group I and 48.3 yrs in Group II. The male to female ratio was 3:7 in Group I and 2:5 in Group II. One patient in Group I had the facet injections at only one level while it was in two patients in Group II (L4/5 or L5/S1). Further one patient in Group I and one in Group two had unilateral facet joint injections at two levels. All the other patients had bilateral facet joint injections at two levels (L4/5 and L5/S1). One patient was excluded from the study as the A-P image obtained was very poor and that an oblique image had to be performed to visualise the facet joint because of obesity. The mean duration of the procedure was 18.33 min (10–25 min) in Group I and 22 min (10–35 min) in Group II (p=0.14, 95%CI −8.5 to +1.4). The patient function score improved from a mean of 20.0% to 32.5% after the injection in Group I, and from 30.0% to 41.0% in Group II. The pain score improved from a mean of 33.3% to 47.2% in Group I, and from 35.6% to 44.4% in Group II. The difference in physical function score (p=0.85, 95% C.I. −15.29 to +18.29), and pain score(p=0.71, 95% C.I. −24.21 to +34.22) between the two groups were not statistically significant.

Conclusions There is no difference in the functional outcome of patients treated by facet joint injections using A-P or oblique imaging. There is no significant difference in the duration of the procedure as well between the two techniques. However, with experience we found that it may be difficult to visualise the facet joint clearly by A-P imaging alone in obese individuals.