Anterior Hip Subluxation due to Lumbar Degenerative Kyphosis and Posterior Pelvic Tilt

Abstract

Nontraumatic anterior subluxation and dislocation of the hip joint are extremely rare. A 58-year-old woman presented to our outpatient clinic with left hip pain with a duration of 15 years. There was no history of trauma or other diseases. Her hip pain usually occurred only on walking and not at rest. Physical examinations demonstrated no tenderness in the hip joint. The range of motion of both hip joints was almost normal. Laxity of other joints was not observed. The bone mineral density of the lumbar spine and proximal femur confirmed a diagnosis of osteoporosis. A plain radiograph showed osteoarthritic changes of the hip joints, severe posterior pelvic tilt, and superior displacement of both femoral heads, especially in a standing position. Three-dimensional computed tomography (3DCT) revealed anterior subluxation of both femoral heads. Seven years after the initial visit, both hip joints showed progression to severe osteoarthritis. Although the exact cause remains unclear, lumbar kyphosis, posterior pelvic tilt, and a decrease in acetabular coverage may have influenced the current case. We should be aware of these factors when we examine patients with hip osteoarthritis.

Relationship between pelvic incidence and osteoarthritis of the hip

“… 4 This posterior tilt of the pelvis results in decreased apparent femoral head coverage 29 - 31 by creating a more vertical articular surface of the acetabulum. 5 Tsuchie et al 32 report a case of non-traumatic anterior subluxation of bilateral femurs in a patient with severe compensatory posterior pelvic tilt. This anterior uncovering of the anterosuperior aspect of the femoral head by the acetabulum may create a dysplastic hip ( Fig.…”

Screw-Hole Clusters in Acetabular Cups: A Morphological Study of Optimal Positioning of Screw-Holes

“…First, our study was based on normal pelvic and acetabular anatomy; thus, it may be possible for our findings for optimal screw-hole locations and pattern on cups to be adopted in primary uncomplicated THA. Change in the lumbosacral spine has been reported to influence pelvic tilt, which may further alter acetabular orientation (21, 22). Analogously, hip dysplasia, ankylosing spondylitis, leg length discrepancy, and other problems may also result in sagittal or coronal pelvic tilt and changes in acetabular orientation.…”

Rapid Hip Osteoarthritis Development in a Patient with Anterior Acetabular Cyst with Sagittal Alignment Change

“…In the prosthetic hip with increased posterior pelvic tilt, excessive wear due to edge loading and anterior dislocation might be a clinical problem [ 14 ]. On the other hand, in the natural hip with increased pelvic tilt, the acetabular coverage for the femoral head is diminished; subsequently the load distribution on the cartilages is altered, finally leading to decreasing weight bearing area and increasing hip stress [ 15 – 17 ]. This is paradoxically explained by the effect of joint preserving acetabular osteotomy procedure.…”