In this case-control study, 23 patients diagnosed as PS by diagnostic injection with ultrasound guidance were selected as the study group. 22 patients who were excluded from the diagnosis of PS and had anteroposterior (AP) direct radiographic imaging were evaluated as the control group. On the AP Pelvic graph, the femoral neck-shaft angle, the distances between predetermined bony landmarks were measured blindly without knowing the diagnosis, and the findings were compared statistically.

This study aims to evaluate whether the anatomical structure of the pelvis predisposes to the etiopathogenesis of the piriformis syndrome.

Piriformis syndrome (PS) is a neuromuscular disorder consisting of pain and symptoms caused by compression of the sciatic nerve and other structures that pass under the piriformis muscle (PM). Due to difficulties in diagnosis, PS is confused with other pathologies such as lumbar disc pathology, lumbosacral radiculopathy, and sacroiliac dysfunction. As a result, patients are exposed to unnecessary and ineffective treatments, even surgery. The main problems in the PS diagnosis are the absence of objective physical examination findings, radiological findings, and a clear etiology. When the pathophysiology and etiology of PS are considered, there is no identifiable cause in most patients. Previous studies suggest that trauma, anatomical variations, and the trigger point in the muscle may cause PS. No study in the literature radiologically examined the pelvis or hip bone morphological features in PS to the best of our knowledge. This study aims to determine whether pelvic or hip bone morphology features pose a risk for PS in this study.

For Piriformis syndrome group (study group);

Inclusion Criteria:

• A dramatic relief of pain following piriformis muscle local anesthetic injection

Exclusion Criteria:

• Having a neurological deficiency
• Having lumbar, sacroiliac, hip, and thoracolumbar pathology (inflammatory or degenerative)
• Operation history at the lumbar and hip region
• Being in the gestational or lactational period
• Body mass index of greater than 35
• History of inflammatory or infectious disease
• Active psychiatric illness, severe systemic, vascular or malign disease

For the control group

Inclusion criteria:

-Having Anteroposterior pelvic radiographs for other medical reasons

Exclusion criteria:

• Having a present piriformis syndrome or a history of piriformis syndrome
• Having a neurological deficiency
• Having lumbar, sacroiliac, hip, and thoracolumbar pathology (inflammatory or degenerative)
• Operation history at the lumbar and hip region
• Being in the gestational or lactational period
• Body mass index of greater than 35
• History of inflammatory or infectious disease
• Active psychiatric illness, severe systemic, vascular or malign disease

The physical medicine and rehabilitation outpatient clinic of Fatih Sultan Mehmet Training and Research Hospital