The effect of sacroiliac joint manipulation on quadriceps and hamstring muscle strengths

Introduction

Knee joint pathologies, in general, are associated with a loss of knee-extensor muscle strength. This loss of muscle strength has been attributed to arthrogenic muscle inhibition (AMI). Manipulation of the sacroiliac (SI) joint has been shown to significantly reduce AMI and increase the strength in the quadriceps muscle group1.
The objective of the study was therefore to investigate the effect of SI joint manipulation on quadriceps and hamstring strengths. This pilot study was as a prospective clinical trial.

Methods

Ten subjects were tested in an experimental fashion using the Cybex Orthotron II Isokinetic Rehabilitation System. Convenience sampling was used to select subjects suffering from both PFPS and SI syndrome, on the ipsilateral side of the knee pain. After all base measurements of the maximum voluntary force (MVF) of contraction were taken; subjects received a grade V manipulation of the sacroiliac joint. Following this, the MVF of the quadriceps and hamstring muscles was retested.
The Wilcoxon Signed Ranks test for matched pairs was used to test for a significant change as a result of the intervention.

Results

Following a grade V manipulation of the SI joint the MVF of the quadriceps and hamstring muscles improved significantly (P= 0.05 and 0.036 respectively).

Discussion/Conclusion

Manipulation of an individual joint not only affects the motor unit activity in the muscles operating over the joint being manipulated, but also in more remote muscles2. The innervation of the SI joint (L2-S4) overlaps with the innervation of the hamstring and quadriceps muscles (L5-S2)3. The altered afferent input arising from the stimulation of mechanoreceptors around the SI joint could change the MN pool excitability of the joint musculature. The resultant decrease in AMI would have led to an increase in the quadriceps muscle strength4.
The results of this study suggest that both quadriceps and hamstring muscle strength increased significantly following SI joint manipulation. A larger sample size and the use of a control group should be considered for future research investigating the effect of manipulative therapy on muscle strength.

References

[1]. Suter, E. et al. (1999). JMPT, 22(3): 149-153.
[2]. Wyke, B.D. (1985). Articular neurology and manipulative therapy: 72 -77.
[3]. Moore, K. L. (1992). Clinically orientated anatomy: 387 +423.
[4]. Suter, E. et al. (2000). JMPT, 23(2): 76-80.