Minimal influence of facet joint anesthesia on isokinetic muscle performance in patients with chronic degenerative low back disorders

Study Design. Experimental design. Objectives. To examine the influence of pain reduction after facet joint in jections on isokinetic back muscle performance Summary of Background Data. Methods for evaluating the effect of facet join t injections vary. Recent studies based their results solely on the patient 's subjective opinion and suggest a need for more objective, concrete, and reliable measurements. Methods. Eighty-seven patients with a degenerative low back disorder (49 wo men and 38 men; mean age, 48 years; range, 22-79) who had facet joint injec tions as a part of preoperative evaluation participated; The mean duration of symptoms was 12.3 years (range, 1-45). The patients underwent isokinetic trunk flexor and extensor muscle strength testing at angular velocities of 60 deg/sec and 120 deg/sec. They perform two tests before the facet joint injections(to eliminate learning effect); All patients had bilateral facet joint injections at L5-S1. Those who did not report pain relief had additio nal injections at L4-L5. The flexion-extension test was repeated 15 minutes after each injection. Pain and fear were registered on visual analog scale s, Results. All 87 patients could perform the isokinetic tests. For extension at deg/sec, a significant improvement was found between the two pretests (P < 0.05). Pain increased significantly from the first to the second pretest (P = 0.02); and a significant decrease in pain was found after the first i njection (P = 0.0001) Fear decreased between each test, with a significant decrease after the first injection. No significant change was found for the muscle strength measurements after facet joint anesthesia, There were only weak correlations between decrease in pain and alteration in muscle perfor mance, ranging from 0.06 to 0.37. Conclusion. Pain reduction after facet joint injections did not influence i sokinetic muscle performance in patients with degenerative low back disorde rs.