Distal femur fractures

Classification and injury mechanism

The typical injury mechanism is a load on the greater trochanter during a fall or impact. Against the background of osteoporosis, the bone can break even under the influence of a low-energy trauma agent. The main predictor of such a low-energy fracture is a history of similar injuries (for example, a distal radius fracture).

In practice, proximal femur fractures are divided into two major groups:

• Lateral (extracapsular): the fracture line runs lateral to the attachment site of the joint capsule (these include trochanteric fractures).
• Medial (intracapsular): the line is located medial to the capsule.

For femoral neck fractures, the Pauwels classification (Pauwels) is frequently used, which assesses the angle of the fracture line relative to the horizontal plane. This is important for understanding biomechanics:

1. Group I (up to 30°): forces of bone fragment approximation (compression) predominate.
2. Group II (30–50°): sliding forces occur.
3. Group III (more than 50°): shearing and dislodging forces act, making the fracture extremely unstable.

Fractures of the femoral head itself are significantly less common. They can manifest as splitting, impression, or be combined with femoral neck fractures and hip dislocations.

Clinical presentation and diagnostics

Diagnosis is based on a number of characteristic clinical symptoms. During examination, it is important to consider that in impacted fractures (when fragments are tightly interlocked), many classical signs may be blunted or absent.

Main symptoms:

• Pain syndrome: localized in the inguinal or trochanteric region, may radiate to the lower leg. At rest, pain is moderate, but it sharply increases with any attempts at movement in the joint.
• Impaired weight-bearing: in non-impacted fractures, weight-bearing on the leg is entirely impossible.
• External rotation: the leg is unnaturally turned outward (determined by the position of the foot and patella). At the same time, the patient cannot actively rotate the leg inward — this is one of the most reliable signs.
• Pain on axial loading: pain flares up in the joint area upon gentle percussion of the heel of the straightened leg or the greater trochanter.
• «Locked heel» sign: lying on the back, the patient is unable to lift the straightened leg; when trying to bend the knee, the heel simply slides along the couch.

Special attention: if an elderly patient is admitted late, and the caregiver's account of the injury mechanism sounds implausible, the factor of abuse (Abuse) should be ruled out.

Surgical tactics and treatment options

Almost all hip fractures are treated surgically. Delayed surgery, bed rest, and immobilization can lead to a fatal outcome. Preoperative skeletal traction is generally not recommended in modern practice.

Osteosynthesis (fixation): Used for non-displaced fractures or in young patients. Parallel screws, dynamic hip screws (DHS), plates, or intramedullary nails are used. The biomechanics of many designs allow the screws to «slide», providing natural fragment compression under load.

Arthroplasty: Performed for displaced fractures in elderly individuals due to the high risk of non-union and osteonecrosis.

• Hemiarthroplasty: only the femoral head is replaced. The artificial head articulates with the patient's own hyaline cartilage of the acetabulum. This is faster and cheaper, but requires healthy cartilage; otherwise, arthritis will develop.
• Total hip arthroplasty: both the head and the acetabulum are replaced. Indicated for patients with a high life expectancy and pre-existing osteoarthritis.

Conservative treatment is used extremely rarely — only as a palliative measure in severe comorbidities or if the patient was unable to walk even before the injury.

Complications and geriatric approach

The injury often triggers a cascade of deterioration, which is why it is called the «geriatric hip fracture syndrome». Less than half of the patients who survive the first year return to their baseline level of independence in daily life.

Late surgical complications:

• In osteosynthesis: non-union, infection, metalwork failure, avascular necrosis of the head (may manifest in 2–4 years).
• In arthroplasty: prosthesis dislocation, loosening, periprosthetic fractures (require revision surgery).

Against the background of hypothermia or dehydration upon admission, physicians may mistakenly overestimate the degree of frailty. Therefore, the prognosis and functional potential must be assessed as objectively as possible, without depriving the patient of a chance for radical treatment due to a false impression of their weakness.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Atypical fractures associated with long-term bisphosphonate use
• Stress fractures of the femoral neck
• Isolated avulsion fractures of the lesser and greater trochanters
• Bone mineral density assessment (DEXA) and FRAX calculator
• Femoral nerve block technique for anesthesia

Other topics in the "Specialized Adult Traumatology" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.