• The study will be randomized clinical trial. This study will be conducted in University of Lahore Teaching Hospital, Lahore, Pakistan. A sample size of 84 will be randomly allocated into two experimental groups, (42 participants in each group), by lottery method. The participants, randomly allocated to the experimental group A, will receive Muscle Energy Technique (METs), Post isometric relaxation technique specifically, in addition with routine physical therapy as TENS, Hot pack, and strengthening exercises. METs will be performed on piriformis, iliopsoas, erector spine muscles, 1 set of 5 repetitions and 10 seconds hold.
• Participants in experimental group B, will get Sacroiliac joint manipulations with routine physical therapy by principal investigator.
• Both experimental groups will receive twelve treatment sessions and those will be given over a period of six weeks (2 sessions per week, each session of 30-40 minutes).
• Assessor will take outcome measures at baseline and at the end of 6th treatment week through Short Form McGill Pain Questionnaire, Roland-Morris Low Back Pain & Disability Questionnaire and Short Form Survey; SF-20.

• Recruitment: Participants will be recruited and referred by orthopedic surgeon, University of Lahore Teaching Hospital to Physical Therapy Department.

• Screening: Diagnostic & pain provocative tests (Faber, Thigh thrust and Gillet tests) will be applied on recruited participants for screening. With all three positive tests, participants will be confirmed for positive SI joint dysfunction and will be considered eligible for entering the study.

• The FABER (Patrick's) Test stands for Flexion, Abduction and External Rotation. The participants will be positioned in supine. The leg will be placed in a figure-4 position (hip flexed and abducted with the lateral ankle resting on the contra-lateral thigh proximal to the knee. While stabilizing the opposite side of the pelvis at the anterior superior iliac spine, an external rotation, abduction and posterior force will be then lightly applied to the ipsilateral knee until the end range of motion would achieve. A further few small-amplitude oscillations would be applied to check for pain provocation at the end range of motion. A positive test will be the one that reproduces the participants' pain or limits their range of movement.

• Thigh thrust test is a posterior pelvic pain provocative test. It will be performed with the participant in supine lying, with the hip flexed to 90° (with bent knee) to stretch the posterior structures. By applying axial pressure along the length of the femur, the femur will be used as a lever to push the ilium posteriorly. One hand will be placed beneath the sacrum to fixate its position while the other hand will be used to apply a downward force to the femur. Broadhurst and Bond suggest adding hip adduction towards the mid line while Laslett & Williams advise to avoid excessive adduction due to discomfort for the participant. Test will be positive if it aggravates the pain in sacroiliac joint.

• The Stork test, also known as the Gillet Test, assesses the movement of the sacroiliac joint between the innominate and sacrum through the clinician's palpation, which may be a useful test for clinical evaluation of a subject's ability to stabilize intra-pelvic motion. The assessment of the Gillet's test involves palpation of the posterior superior iliac spine (PSIS). There are 2 phases to the Gillet's test: the stance phase and the hip flexion or swing phase. To perform this test, the patient will be asked to stand while the examiner will palpate the posterior superior iliac spine (PSIS) with one thumb and will palpate the base of the sacrum with the other thumb medial to the PSIS. The participants will be then instructed to stand on one leg while pulling the hip of the side being palpated into 90° or more of hip flexion. The test will then be repeated on the other side and compared bilaterally. The principal investigator will compare each side for quality and amplitude of movement. The test will be positive when the PSIS on the ipsilateral side (same side of the body) of the knee flexion move minimally in the inferior direction, doesn't move or is associated with pain. A positive test will be an indication of sacroiliac joint hypo-mobility.

• Randomization and Allocation: Afterwards, participants confirming the eligibility criteria will be randomly allocated, through lottery method, into two experimental groups (Group A, Group B).

• Blindness: Study will be single, assessor blinded and an independent investigator will perform randomization and will inform the patients and therapist about the allocation.

• Intervention: The participants, randomly allocated to the experimental group A, will receive METs (Post isometric relaxation technique specifically) in addition with routine physical therapy (TENS, Hot pack, and strengthening exercises). METs will be performed on piriformis, iliopsoas, erector spine muscles, 1 set of 5 repetitions and 10 seconds hold. Participants in experimental group B, will get Sacroiliac joint manipulations with routine physical therapy by principal investigator.

• Duration: Twelve treatment sessions will be given over a period of six weeks (2 sessions per week, each session of 30-40 minutes).

• Outcome Variables and Measures

  1. Pain (Short Form McGill Pain Questionnaire)
  2. Functional Disability (Roland-Morris Low Back Pain & Disability Questionnaire)
  3. Quality of Life (Short Form Survey; SF-20)

• Outcome measures will be taken at baseline and at the end of last treatment session i.e. 6th week. Collected data will be than analyzed.

Inclusion Criteria:

• Pre-diagnosed cases referred from orthopedic surgeon
• History of fall on buttock, lift and twist maneuver, overzealous kick
• Acute onset of sacral pain within period of 6 weeks
• FABER, Thigh thrust and Gillet sacral joint diagnostic tests must be positive to confirm the SI joint dysfunction before allocation

Exclusion Criteria:

• General low back pain, Sciatic pain, piriformis syndrome, Hip joint pathology
• SI joint spondylosis or ankylosing spondylitis
• Red flag signs positive (constant pain without movement, sudden weight loss with pain in time, lower limbs' undefined weakness, neurological signs)
• Structural leg length discrepancy and recent pregnancy
• Participants with other spinal pathologies (e.g. Osteomyelitis, Pott's disease, Cauda equine syndrome, spondylolisthesis or spondyloptosis, Lumbar disc herniation etc.)
• Participants with other systemic illnesses (e.g. cardiovascular disorders, gastrointestinal disorders, renal function disorders, Liver function disorders etc.)
• Participants with traumatic injuries (e.g. fractures, dislocations, sports injuries, road traffic accidents)

Study will be single and assessor blinded. Participants will be masked about other groups but they will know what treatment they will be receiving or what exercises they will be doing. Principal investigator would also not be masked or blinded because investigator would be applying the techniques on participants of both group. So participant and and principal investigator cannot be blinded. Only assessor will be blinded and he will take outcome measures without knowing the problem and treatment techniques.