Our study had some limitations which should be noted. The pre–post test design did not include a control group; consequently, the results cannot be considered evidence in support of the clinical efficacy of SMT for patients with LDH and SIJ hypomobility. A controlled trial is advisable in which combined manipulations are compared to lumbar or SIJ manipulation separately, to elucidate whether using both lumbar and SIJ manipulation together yields better outcomes than using a single type of manipulation. The small sample size and lack of long-term follow-up are other limitations. In addition, we are aware that measuring physiologic responses to SMT by recording electromyographic activity of the spinal muscles, the myotomes and dermatomes of the involved nerve roots, would strengthen the results of future studies. Also, more reliable tests for SIJ dysfunction are available and should be used in future studies. Despite these limitations, we addressed some shortcomings of previous studies. The strengths of the present study were matching of the physical examination findings with imaging findings, considering SIJ hypomobility in the treatment of patients with LDH, and the application of spinal thrust manipulation alone rather than a combination of therapeutic methods.