INTRODUCTION: The sacroiliac joint (SIJ) can be a source of low back pain. It is usually detected in the buttock, groin and may refer to lower extremity. Thus, it mimics pain from other well‐known lumbar disorders. The purpose of this study is to detect the area of pain and numbness caused by SIJ dysfunction.
METHODS: We examined the area of pain and numbness in 100 patients with SIJ pain treated conservatively (Group A) and 20 with severe pain treated by joint arthrodesis (Group B). We diagnosed as having SIJ pain when the patient showed all three criteria: 1) lumbo‐gluteal pain on one side, 2) positive findings on at least one of the three provocation tests: Gaenslen’s test, Patrick’s test, and modified Newton’s test, 3) pain relief more than 70% after the SIJ injection. Group A consisted of 42 males and 58 females with an average age of 46 years (range, 18‐75) while Group B 7 males and 13 females with that of 45 years (range, 24‐68).
RESULTS: In Group A, pain was detected mainly at around the posteior superior iliac spine (PSIS) in 94 patients, groin in 23, and at areas of ischial tuberosity, L4/5 or L5/S1, lateral thigh, lateral malleolus. Numbness was noticed at areas of lateral thigh, posterior thigh, medial leg, medial malleolus, sole.
In Group B, pain was detected at around PSIS in all of 20 patients, groin in 13, and at areas of greater trochanter, ischial tuberosity, knee joint, lateral malleolus. Numbness was noticed at areas of buttock, lateral thigh, lateral malleolus, whole lower leg, medial sole. In most patients, symptoms in the lower extremity did not correspond with the dermatome of lumbar nerve roots.
DISCUSSION: The present study demonstrated that the SIJ pain was mainly detected in the buttock around the PSIS and could refer to every area in the thigh and leg. The pain and numbness in the lower extremity not corresponding with the dermatome of lumbar nerve roots may be originated from the SIJ.