Pelvic Radiography: Clinical Applications and Technique
Pelvic radiography is a standard imaging modality that provides visualization of the bony pelvis and proximal femurs, primarily used as the initial imaging examination for suspected hip fractures, trauma evaluation, and assessment of developmental hip disorders. 1, 2
Technical Aspects
Standard Views
- Anteroposterior (AP) view of the pelvis: Primary view that allows visualization of both hips for comparison
- Cross-table lateral view: Provides orthogonal perspective of the symptomatic hip
Positioning Considerations
- Proper positioning is critical for diagnostic accuracy
- Some institutions may include a separate AP view of the symptomatic hip in addition to the AP pelvis and cross-table lateral views 1
- Patient positioning affects radiographic measurements and interpretation of findings 3
- Standing (weight-bearing) positioning may better reflect functional appearances of the hip joint compared to supine positioning for certain clinical scenarios 3
Clinical Applications
Hip Fracture Evaluation
- Radiography detects approximately 90% of proximal femoral fractures 2
- Complete initial radiographic assessment should include:
- When radiographs are negative but clinical suspicion remains high:
Trauma Assessment
- Part of the standard trauma series radiographs (typically AP chest and pelvis) 1
- Evaluates for unstable pelvic injuries and hip dislocation in trauma patients 1
- Sensitivity of AP pelvic radiographs in trauma is approximately 77% using CT as the reference standard 1
- Most commonly missed injuries are to the sacrum, sacroiliac joints, and loose bodies in the hip joints 1
- In hemodynamically stable trauma patients with negative physical examination, the utility of routine pelvic radiography has been questioned 4
Developmental Dysplasia of the Hip (DDH)
- Pelvic radiography becomes the preferred confirmatory imaging modality for DDH after the appearance of the ossific nucleus (typically 4-6 months of age) 1
- Normal pelvic radiograph at 4 months can reliably exclude DDH in children with risk factors 1
- For infants with suspected hip dysplasia, radiographs are often obtained between 4-6 months of age 1
- Limitations include:
- Variable timing for appearance of the ossific nucleus (1.5-8 months of age)
- Delayed and often eccentric appearance in dysplastic hips 1
Pelvic Floor Dysfunction
- Limited utility in functional assessment of pelvic floor dysfunction
- MRI defecography or dynamic pelvic floor MRI are preferred for evaluation of pelvic organ prolapse 1
Limitations and Pitfalls
- Incomplete radiographic assessment may miss fractures and lead to misdiagnosis 2
- Failing to include the pelvis in the initial radiographic assessment may miss associated pelvic fractures 2
- Variations in image quality and radiographic centering points are frequently reported 5
- Radiographic centering point and pelvic axial rotation can vary significantly between examinations, affecting image interpretation 5
- Limited sensitivity for detecting certain injuries compared to advanced imaging modalities like CT or MRI 1
Emerging Technologies
- Deep learning algorithms are being developed to improve detection of trauma-related findings on pelvic radiographs 6
- PelviXNet, a multiscale deep learning algorithm, has demonstrated comparable performance to radiologists and orthopedic surgeons in detecting pelvic and hip fractures 6
In summary, pelvic radiography remains a fundamental imaging modality for initial assessment of hip and pelvic pathology, particularly for suspected fractures and developmental disorders. While it has limitations compared to advanced imaging techniques, its accessibility, low cost, and ability to provide valuable diagnostic information make it an essential tool in clinical practice.