What is a subcapital fracture of the femur head in an elderly patient with a potential history of osteoporosis?

What is a Subcapital Fracture of the Femur Head

A subcapital fracture of the femur is a fracture through the femoral neck immediately below the femoral head at the junction of the head and neck, representing one of the most common types of hip fractures in elderly patients with osteoporosis. 1

Anatomic Definition and Location

• The fracture occurs at the subcapital region, which is the narrow portion of the femoral neck directly adjacent to and just below the femoral head 2, 3
• This location is distinct from intertrochanteric fractures (which occur between the greater and lesser trochanters) and subtrochanteric fractures (which occur below the lesser trochanter) 1
• The fracture line typically runs through the junction between the femoral head and neck, making it an intracapsular fracture with significant implications for blood supply 4

Clinical Context in Elderly Patients with Osteoporosis

• Subcapital fractures are extremely common in elderly osteoporotic patients, typically resulting from ground-level falls at home (accounting for approximately 70% of cases) 2, 1
• These fractures result in approximately 300,000 hospitalizations per year in the United States and are nearly twice as common in women as in men 1
• The 1-year mortality rate is substantial: 22% for women and 33% for men 1

High-Risk Nature and Complications

• Subcapital fractures are considered high-risk injuries because of their propensity for complications including avascular necrosis (AVN), nonunion, and delayed union 1
• The intracapsular location compromises the blood supply to the femoral head, as the fracture disrupts the retinacular vessels that supply the femoral head 4
• If not recognized and treated promptly, these fractures have increased rates of delayed union, nonunion, displacement, and avascular necrosis 1

Classification and Displacement

• Subcapital fractures are commonly classified using the Garden staging system (stages I-IV based on degree of displacement and alignment) 3
• Garden stage III and IV fractures (displaced fractures) have a characteristic radiographic appearance that can sometimes mimic pathologic fractures due to external rotation and displacement of the distal fragment 3
• Approximately 17% of subcapital fractures demonstrate radiographic features that simulate pathologic fractures, occurring primarily in Garden stage III (32%) and stage IV (24%) fractures 3

Diagnostic Imaging Approach

• Radiography is the initial imaging modality of choice, with standard views including an anteroposterior (AP) view with 15 degrees of internal hip rotation and a cross-table lateral view 1
• When radiographs are negative or indeterminate but clinical suspicion remains high, MRI without contrast is the preferred advanced imaging modality for detecting occult fractures 1
• Delays in diagnosis and treatment are associated with increased mortality, complication rates, and hospital length-of-stay 1

Treatment Implications

• Treatment decisions depend on fracture displacement, patient age, functional status, and pre-existing osteoarthritis 1
• Stable non-displaced fractures can be treated with percutaneous cannulated screw fixation 1
• Displaced subcapital fractures in healthy, active, independent elderly individuals without cognitive dysfunction are best treated by total hip arthroplasty 1, 5
• In frail elderly patients, hemiarthroplasty is preferred because operative time is shorter and dislocation risk is lower, though functional outcomes may be less optimal than total hip replacement 1

Critical Pitfalls to Avoid

• Do not assume a patient can be safely discharged simply because they can still walk - patients with minimally displaced subcapital fractures can maintain weight-bearing ability initially 5
• Do not delay surgical consultation - the American Academy of Orthopaedic Surgeons recommends urgent orthopedic surgical consultation and operative management within 24-48 hours 5
• In patients younger than 60 years with subcapital fractures and no clear trauma history, suspect fracture associated with extensive osteonecrosis, especially if risk factors for AVN are present or the contralateral hip shows osteonecrosis 6
• Radiographic appearance mimicking pathologic fracture does not necessarily indicate malignancy - this appearance commonly results from external rotation and displacement of fracture fragments in Garden stage III and IV fractures 3

Secondary Prevention Requirements

• Every patient aged 50 years and over with a subcapital fracture requires systematic evaluation for subsequent fracture risk using a Fracture Liaison Service model 1, 7, 5
• Pharmacological treatment should use drugs demonstrated to reduce vertebral, non-vertebral, and hip fracture risk, with regular monitoring for tolerance and adherence 1