Drehmann sign

Drehmann Sign is a clinical sign often associated with Slipped Capital Femoral Epiphysis (SCFE) and other hip pathologies. It is named after German surgeon Georg Drehmann, who first described it in the early 20th century. The sign is considered positive when, during passive flexion of the hip, there is involuntary external rotation of the hip. This phenomenon is indicative of underlying hip pathology, most commonly SCFE, but can also be seen in conditions such as Legg-Calvé-Perthes Disease and other hip disorders.

Etiology

The Drehmann Sign is primarily associated with SCFE, a condition where the head of the femur slips posteriorly and inferiorly with respect to the neck of the femur. This slippage is most common during periods of rapid growth, typically in adolescence. The exact etiology of SCFE is multifactorial, involving mechanical, hormonal, and genetic factors. The Drehmann Sign is a reflection of the mechanical disruption caused by the slippage, leading to abnormal contact between the femoral head and the acetabulum, which in turn causes the characteristic external rotation during hip flexion.

Clinical Presentation

Patients presenting with a positive Drehmann Sign often report hip or knee pain, limping, and a decreased range of motion in the affected hip. The sign is elicited by passively flexing the hip while the patient is in a supine position. A positive sign is indicated by the involuntary external rotation of the hip during this maneuver. It is important to note that while the Drehmann Sign is indicative of hip pathology, it is not specific to SCFE and should be considered in the context of the patient's overall clinical presentation.

Diagnosis

The diagnosis of conditions associated with a positive Drehmann Sign, such as SCFE, involves a combination of clinical examination and imaging studies. Plain radiographs of the hip, including anteroposterior and frog-leg lateral views, are essential for diagnosing SCFE. Advanced imaging techniques, such as Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) Scan, may be required in cases where the diagnosis is uncertain or to assess the extent of the femoral head displacement.

Treatment

The treatment of SCFE, and by extension conditions presenting with a positive Drehmann Sign, is primarily surgical. The goal of surgery is to stabilize the slipped epiphysis and prevent further slippage. This is typically achieved through the placement of screws across the growth plate of the femur. Early diagnosis and treatment are crucial to prevent complications such as avascular necrosis of the femoral head and osteoarthritis of the hip.

Prognosis

The prognosis for patients with a positive Drehmann Sign depends on the severity of the underlying hip pathology and the timeliness of treatment. Early detection and management of SCFE can lead to good functional outcomes and a low incidence of complications. However, delayed diagnosis and treatment can result in significant morbidity, including chronic pain, reduced hip mobility, and the development of degenerative hip disease.