Pertrochanteric fracture of an ankylosed hip with protrusio acetabuli treated by PFNA nail: A case report of a rare case

INTRODUCTION: Hip fractures are the cause of significant morbidity and mortality, aggravated by the existence of an underlying hip pathology. The association of a pertrochanteric fracture with an ankylosed hip and acetabular protrusion is extremely rare. It has not been reported in the literature and the optimal management remains unknown. The surgical treatment indicated for trochanteric fractures allows patients to restore their autonomy quickly while avoiding complications. CASE PRESENTATION: We present the case of a 45-year-old patient who was followed for multiple myeloma and treated with chemotherapy. Following a fall on the pelvis, we found a pertrochanteric fracture with an ankylosed hip and acetabular protrusion. The patient was treated with a PFNA nail based on some principles to improve stabilization, with good results. CLINICAL DISCUSSION: The combination of acetabular protrusion and hip ankylosis alters the biomechanics of this joint by displacing the center of rotation inward and decreasing abductor muscle tension while increasing the lever arm. Several surgical approaches have been reported on case reports with different results. No consensus has been reached for this entity because of its rarity and the absence of a large sample. The result reported for our patient could make cephalomedullary nailing a good option since it allows preservation of the gluteal musculature, early management of the patient and recovery of the pre-morbid state. CONCLUSION: The lack of consensus and the changes caused by this hip condition are a challenge for orthopedists. We treated our patient with a PFNA nail based on a few principles necessary to optimize stability with a satisfactory result.