This 1932 paper by Pomeranz is a comprehensive narrative review of intrapelvic protrusion of the acetabulum, known as Otto pelvis. It synthesizes the international literature from Otto's 1824 original description through 79 reported cases, adds 6 institutional cases from the Hospital for Joint Diseases, and proposes a unifying pathomechanical framework. The central question: what actually causes this deformity, and is gonorrhea the responsible agent?
When you encounter a hip with progressive medial joint space loss, acetabular floor migration, and preserved femoral head architecture on plain films, the differential is broader than rheumatoid arthritis alone.
Pomeranz established that protrusio acetabuli is a radiographic pattern with multiple causes: inflammatory arthritis, Paget's disease, osteomalacia, neuropathic arthropathy, and prior infection can all produce it. This is why your workup should be directed at the underlying systemic disease, not a single pathogen.
The clinical rule from this paper: the femoral head must be relatively preserved for protrusion to develop. When the head is destroyed (as in aggressive pyogenic infection), bony ankylosis occurs instead. When you see protrusion with an intact head, the underlying disease was chronic and low-grade — this narrows your differential toward inflammatory arthropathy, Paget's, or osteomalacia.
For preoperative planning in acetabular reconstruction, remember that bilateral involvement occurs in roughly 37% of cases and that extreme protrusion can extend to the sacroiliac joint, with implications for both implant positioning and, historically, for obstetric management.
This 1932 paper by Pomeranz is a comprehensive narrative review of intrapelvic protrusion of the acetabulum, known as Otto pelvis. It synthesizes the international literature from Otto's 1824 original description through 79 reported cases, adds 6 institutional cases from the Hospital for Joint Diseases, and proposes a unifying pathomechanical framework. The central question: what actually causes this deformity, and is gonorrhea the responsible agent?
When you encounter a hip with progressive medial joint space loss, acetabular floor migration, and preserved femoral head architecture on plain films, the differential is broader than rheumatoid arthritis alone.
Pomeranz established that protrusio acetabuli is a radiographic pattern with multiple causes: inflammatory arthritis, Paget's disease, osteomalacia, neuropathic arthropathy, and prior infection can all produce it. This is why your workup should be directed at the underlying systemic disease, not a single pathogen.
The clinical rule from this paper: the femoral head must be relatively preserved for protrusion to develop. When the head is destroyed (as in aggressive pyogenic infection), bony ankylosis occurs instead. When you see protrusion with an intact head, the underlying disease was chronic and low-grade — this narrows your differential toward inflammatory arthropathy, Paget's, or osteomalacia.
For preoperative planning in acetabular reconstruction, remember that bilateral involvement occurs in roughly 37% of cases and that extreme protrusion can extend to the sacroiliac joint, with implications for both implant positioning and, historically, for obstetric management.