Does the choice of spinal level treated during posteroanterior (PA) mobilisation affect treatment outcome?

The purpose of this study was to establish whether posteroanterior (PA) mobilisation is more effective in relieving low back pain (LBP) when the treatment is delivered to the level identified by the therapist as responsible for the LBP, than when delivered to a randomly selected level. One physiotherapist and 120 subjects suffering LBP participated. Prior to treatment allocation, baseline measurements were taken. The therapist then assessed subjects and nominated the preferred treatment grade and spinal level to be treated. The subjects were then randomly allocated to one of two groups; Group 1 received the treatment at the level identified by the therapist as responsible for the symptoms, whereas Group 2 received treatment at a random lumbar level. In both groups the originally nominated treatment grade was used and all subjects received one treatment session with follow-up measures taken immediately after intervention. Two-way analysis of variance (ANOVA) was used to analyse the data; the first factor was treatment group and the second factor was the direction of the patient's worst movement. There was greater reduction in pain intensity when the mobilisation was applied to the symptomatic level rather than to a randomly assigned level (F_1,114 = 4.504, p = 0.036). There was also an interaction effect on pain reduction between the two factors (F_2,114 = 3.301, p = 0.04). The results of this study confirm that the level treated is a determinant of the immediate analgesic effect of PA mobilisation treatment for LBP. Other parameters of treatment dose such as the direction, peak force, and frequency of PA mobilisation await formal investigation.