Differential diagnosis of pain
The classic clinical presentation of a femoral fracture is not occult: there is a clear history of trauma, obvious deformity, acute pain, and inability to bear weight along the axis. However, if a patient complains of subacute or progressive hip pain without prior trauma, a thorough differential diagnosis must be performed.
Key causes of pain:
- Endoprosthesis instability: can be either aseptic or septic (infectious) in nature.
- Malignant neoplasms (Malignancy): may present as pain in the hip, knee, or thigh. Changes in bone structure on radiographs without a history of trauma are an indication for further workup. The most frequent tumor of the femur is metastatic disease.
- Stress (fatigue) fractures: pain increases with axial loading.
Red flags: in a high-energy femoral shaft fracture, one must always maintain vigilance for a concomitant ipsilateral femoral neck fracture.
Epidemiology and risk factors for femoral fractures
Shaft and distal fractures account for less than 1% of all fractures, with the incidence showing a bimodal age distribution. The global incidence is 15–45 cases per 100,000 population per year. In low-income countries, this risk is 2 times higher due to poverty, poor road safety, and violence.
Location ratio (distal to the hip joint):
- Shaft fractures occur 5 times more frequently than distal fractures.
- Shaft fractures are 2.5 times more frequent than subtrochanteric (subtrochanteric) fractures.
A special group consists of atypical subtrochanteric femoral fractures. Their absolute risk is extremely low (3.2–50 cases per 100,000 person-years), but they are associated with long-term bisphosphonate use for osteoporosis and also occur in patients after bariatric surgery (sleeve gastrectomy or gastric bypass) against the background of nutritional deficiency.
Conservative and surgical treatment
In high-energy trauma, emergency immobilization is paramount. A historically important role here was played by the Thomas splint (Thomas splint), introduced in 1916 by Robert Jones, which reduced mortality from femoral fractures from 80% to 20%.
Conservative treatment (skeletal or skin traction) is used primarily in low-income countries, where bone healing (consolidation) occurs in approximately 50 days. However, with prolonged bed rest, the complication rate reaches 50% (deep vein thrombosis, pressure ulcers within hours, muscle atrophy, hypostatic pneumonia).
Surgical treatment (Osteosynthesis):
- Intramedullary nailing (IM nailing): The treatment of choice for diaphyseal fractures. Performed after closed reduction (closed reduction). The nail is inserted antegrade or retrograde. The method is minimally invasive, preserving the soft-tissue envelope and blood supply.
- Plate osteosynthesis (plates and screws - ORIF): Indicated for periarticular and intra-articular fractures (e.g., Hoffa fracture), where rigid anatomical fixation is required to prevent post-traumatic osteoarthritis. It is inferior in strength to nails, requires strict restriction of axial loading, but allows immediate kinesiotherapy.
Management of polytrauma
The management of patients with multiple injuries requires choosing between two strategies:
- Damage control orthopaedics (Damage control orthopaedics): emergency temporary stabilization with external fixation devices (EFD) or traction in severe patients unable to tolerate prolonged surgery.
- Early total care (Early total care): definitive osteosynthesis within 24 hours. Improves pain control and patient care.
Pathophysiology of arthritis (indications for arthroplasty)
Joint destruction requiring replacement with an endoprosthesis is most commonly associated with arthritis (exemplified by the tibiofemoral and patellofemoral joints of the knee):
- Osteoarthritis (OA): A "wear and tear" disease. Asymmetrical involvement (most commonly the medial compartment). Articular cartilage loses proteoglycans, compensatory subchondral sclerosis develops, and osteophytes form. Synovial inflammation is secondary.
- Rheumatoid arthritis (RA): An autoimmune symmetrical condition. Synovial membrane inflammation stimulates osteoclasts and suppresses osteoblasts, leading to periarticular bone loss and cartilage destruction.
Briefly: answers to topical questions
What types of endoprosthesis instability exist and what are their radiographic signs?
Both septic and aseptic endoprosthesis instability are distinguished. Radiography may not provide a definite diagnosis, but it visualizes soft tissue swelling or signs of instability. Evaluating serial radiographs is critically important to detect minimal progressive changes. Skeletal scintigraphy reveals increased radiopharmaceutical uptake around the prosthesis due to osteolysis, although the picture in infection can be identical to aseptic loosening.
What are the contraindications to intramedullary femoral nailing?
In osteomyelitis, the use of internal fixators, including intramedullary nails, is impossible due to the high risk of exacerbating the infectious process. In children, massive intramedullary implants are contraindicated due to the risk of damaging the growth plates.
Which arteries are injured in a femoral neck fracture, leading to avascular necrosis of the femoral head?
A femoral neck fracture can damage blood vessels running along the neck that supply perfusion to the femoral head. Disruption of blood flow can lead to avascular necrosis (osteonecrosis) of the head. The blood supply includes the medial and lateral circumflex femoral arteries, which form an arterial ring, as well as ascending cervical branches arising from it that run parallel to the neck and nourish the head.
The triad of fat embolism syndrome: "Respiration, Consciousness, Skin" — respiratory distress, altered mental status, and petechial rash after a femoral fracture.
Class and exam questions
Why is an intramedullary nail preferred for diaphyseal fractures?
The nail is mechanically stronger, and its placement allows the soft-tissue envelope of the fracture zone to remain intact, which minimizes the risk of infection.
What is the core concept of damage control orthopaedics?
This is temporary fracture stabilization (e.g., using an external fixator) in patients with severe polytrauma for whom early prolonged surgery poses a life threat.
How to differentiate the pathogenesis of osteoarthritis from rheumatoid arthritis?
Osteoarthritis is biomechanical cartilage "wear and tear" with the development of osteophytes and sclerosis. Rheumatoid arthritis is primary autoimmune synovial inflammation leading to bone loss (osteoclast activation).
What else to study on this topic
- Specifics of using locking screws in intramedullary osteosynthesis
- Biomechanics of the tibiofemoral joint and axial load distribution
- Impact of bariatric surgery on bone tissue metabolism
- Principles of primary, secondary, and tertiary prevention of high-energy trauma
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