Sacroiliac Sprain/Strain
The sacroiliac (S.I.) joint is formed by the articulation (where bone meets bone) of the broad flat-boned ilium and the triangular shaped sacrum. There is a right and a left S.I. joint and both are of a jagged S-shaped configuration. These sacroiliac joints allow for slight pelvic rocking during walking or running to aid in mobility and yet are inelastic enough to serve as a stabilizing force in the pelvis.
The problem comes when associated muscles or ligaments of the S.I. joint are damaged due to lifting excessive weights or due to a severe blow directed toward the pelvis. The pain may be present for several weeks following the injury but is usually not of a long-term duration unless the injury involves the disc or other vertebral joints. This pain is usually worse at the site of the joint but may be referred down the leg and is usually relieved by rest. Pressure at the joint site will almost always reveal tenderness which is helpful in localizing the problem.
The patient who suffers from S.I. joint injury will tend to tilt away from the side of involvement, have a guarded walk and experience tight hamstring muscles. A misstep or jar to the heel will result in a sharp localized pain at the involved joint. Also, anything that will relieve tension in the hamstrings, such as sitting, will tend to relieve the pain of S.I. sprain/strain.
The patient's standing posture may help to reveal a sacroiliac sprain. The observer will notice that the patient lists away from the side of S.I. joint involvement, placing the weight on the uninvolved side. He will also have difficulty flexing the trunk forward and may experience pain by leaning backwards looking towards the ceiling.
An orthopedic test that is usually positive in sacroiliac sprain is the following: The patient is asked to lay flat on his back on a firm table with both legs extended. Then he is asked to raise both legs together slightly off the table. If pain is produced in the low back and pelvic region, then S.I. sprain is probably involved.
