Proximal Femur Fractures: Epidemiology, Anatomy, Biomechanics & Management

Introduction & Epidemiology

Proximal femur fractures, encompassing both femoral neck and intertrochanteric fractures, represent a substantial global public health burden. These injuries are predominantly observed in the geriatric population, often as a sequela of low-energy trauma in the context of osteoporosis. The intricate management decisions, significant morbidity, and mortality associated with these fractures necessitate a profound understanding of their epidemiology, biomechanics, and surgical tenets.

The ability to precisely capture, analyze, and disseminate data pertaining to orthopedic injuries is paramount for informing public health initiatives, resource allocation, and clinical practice guidelines. For instance, the systematic aggregation of data on the number and type of orthopedic injuries per year and the number and type of orthopedic injuries per province (as suggested in the initial prompt) provides a critical foundation. Such structured epidemiological data, when presented in an unambiguous "container" – analogous to a meticulously crafted code block for a digital platform – allows for rapid, accurate interpretation and robust decision-making. This rigorous approach to data management facilitates the identification of high-risk populations, geographical hotspots, and secular trends in injury patterns, ultimately guiding preventative strategies and optimizing healthcare delivery.

The incidence of proximal femur fractures is projected to escalate globally due to an aging population. Worldwide, it is estimated that the annual incidence will rise from 1.66 million in 1990 to 6.26 million by 2050. These fractures carry significant socioeconomic implications, with high rates of long-term disability, loss of independence, and substantial healthcare costs. Mortality rates one year post-fracture range from 14% to 36%, often attributable to pre-existing comorbidities and complications arising from prolonged immobility and surgery. Understanding the specific subtypes – intracapsular (femoral neck) versus extracapsular (intertrochanteric) – is crucial, as their biomechanics, vascularity, and surgical management strategies differ significantly. These distinctions underscore the necessity for precise data categorization to truly master the "container" of information for effective clinical and public health application.

Surgical Anatomy & Biomechanics

Femoral Neck Anatomy

The femoral neck connects the femoral head to the shaft, angling superiorly, medially, and anteriorly. The angle of inclination, typically 125-135 degrees, and the angle of anteversion, typically 10-20 degrees, are critical for hip joint mechanics and are often altered in pre-existing pathology or developmental deformities. The primary blood supply to the femoral head is predominantly from the medial femoral circumflex artery (MFCA) via its ascending cervical branches. These vessels traverse along the posterior and superior aspects of the femoral neck, entering the head predominantly through the retinacular arteries and foveal artery (ligamentum teres artery). Femoral neck fractures, being intracapsular, often disrupt this precarious blood supply, leading to a high risk of osteonecrosis of the femoral head (ONFH), especially in displaced fractures. The joint capsule attaches anteriorly to the intertrochanteric line and posteriorly near the base of the neck, rendering femoral neck fractures true intracapsular injuries. Synovial fluid within the joint capsule contains fibrinolytic enzymes that can contribute to non-union by inhibiting callus formation, further complicating healing.

Intertrochanteric Region Anatomy

The intertrochanteric region lies extracapsular, extending from the base of the femoral neck distally to the lesser trochanter. This region is highly cancellous, rich in blood supply from the lateral femoral circumflex artery and perforating branches of the profunda femoris artery, which explains the generally higher union rates compared to femoral neck fractures. Key anatomical landmarks include the greater trochanter laterally, the lesser trochanter medially, and the intertrochanteric line/crest connecting these two structures anteriorly and posteriorly, respectively. The vastus lateralis originates from the greater trochanter and intertrochanteric line, while the iliopsoas inserts onto the lesser trochanter. The robust muscular attachments and rich vascularity of this region contribute to its suitability for internal fixation.

Biomechanics of Fracture Patterns

Femoral Neck Fractures:
These fractures typically result from shear and bending forces. The Garden classification (Type I-IV) describes the degree of displacement and impaction, correlating with the risk of vascular compromise and subsequent ONFH. Pauwels classification, based on the angle of the fracture line to the horizontal, indicates the stability of the fracture pattern and the propensity for shear forces to cause displacement and non-union (Type I <30°, Type II 30-50°, Type III >50°). A steeper angle (Pauwels III) suggests higher shear forces and greater instability.

Intertrochanteric Fractures:
These fractures are characterized by comminution of the cancellous bone. The stability of the fracture is determined by the integrity of the posteromedial cortex, particularly the lesser trochanter and calcar femorale. An unstable fracture is defined by comminution of the posteromedial cortex, reverse obliquity (fracture line running from lateral and proximal to medial and distal), or subtrochanteric extension. Unstable patterns are prone to varus collapse and cut-out of the fixation device, necessitating constructs that provide greater biomechanical stability, such as intramedullary nailing. Stable fractures typically maintain contact between the femoral head and shaft fragments, allowing for load sharing across the fracture site.

Indications & Contraindications

The management of proximal femur fractures is highly individualized, considering patient age, physiological status, fracture pattern, and bone quality. The primary goal is early mobilization to prevent complications of immobility and restore functional independence.

Operative Indications

• Nearly all proximal femur fractures, except for rare instances of truly undisplaced, stable, non-ambulatory patients, are managed surgically.
• Femoral Neck Fractures:
  • Displaced fractures in physiologically younger, active patients (often 60-70 years old) without severe comorbidities: Open reduction internal fixation (ORIF) or hemiarthroplasty/total hip arthroplasty (THA). The decision between ORIF and arthroplasty depends on age, activity level, and fracture pattern.
  • Displaced fractures in older, less active patients: Hemiarthroplasty (unipolar or bipolar) or THA (in select cases with pre-existing osteoarthritis).
  • Undisplaced (Garden I or II) femoral neck fractures: ORIF (multiple cannulated screws) to prevent displacement and promote healing.
• Intertrochanteric Fractures:
  • All types (stable and unstable) in ambulatory or potentially ambulatory patients.
  • Surgical fixation (e.g., sliding hip screw, intramedullary nail) aims to achieve stable fixation, allow early weight-bearing, and promote union.

Contraindications

• Absolute Contraindications (rare):
  • Moribund patient with non-salvageable medical comorbidities, where the risk of surgery far outweighs any potential benefit.
  • Active systemic infection or local infection at the surgical site.
  • Extremely poor bone quality where fixation is unlikely to hold.
• Relative Contraindications:
  • Severe, uncontrolled medical comorbidities that significantly increase anesthetic and surgical risk (e.g., severe cardiac disease, recent myocardial infarction, uncontrolled diabetes). These usually warrant medical optimization prior to surgery, rather than outright contraindication.
  • Pre-existing dementia or non-ambulatory status in very frail patients, where conservative management (comfort care) may be considered, though surgery often facilitates easier nursing care and pain control even in these populations.

Operative vs. Non-Operative Indications

Pre-Operative Planning & Patient Positioning

Thorough pre-operative planning is crucial for optimizing outcomes and minimizing complications.

Pre-Operative Planning

1. Patient Assessment and Optimization:
   • Medical Workup: Comprehensive history and physical examination, focusing on cardiac, pulmonary, renal, and neurological systems. Pre-existing conditions (e.g., anticoagulation, diabetes, malnutrition) must be identified and optimized. Anesthesia consultation is mandatory.
   • Imaging:
     • Standard AP and lateral radiographs of the hip are essential for fracture classification and templating.
     • Contralateral hip views can aid in assessing the normal neck-shaft angle and version.
     • Pelvis AP view to rule out associated pelvic injuries.
     • CT scan may be considered for complex comminution, occult fractures, or pre-existing deformity, particularly in femoral neck fractures in younger patients where precision of reduction is paramount.
   • Templating: For arthroplasty, templating with standardized radiographs helps determine appropriate implant size (head, stem, offset) and guides component placement. For internal fixation, templating can assist in planning screw or nail length and diameter.
2. Surgical Strategy Development:
   • Fracture Classification: Garden, Pauwels for femoral neck; AO/OTA for intertrochanteric. This guides implant choice.
   • Implant Selection:
     • Femoral Neck: Cannulated screws for undisplaced; hemiarthroplasty/THA for displaced (consider patient age, activity, bone quality).
     • Intertrochanteric: Sliding hip screw (DHS) for stable patterns; intramedullary nail (cephalomedullary nail) for unstable, reverse oblique, or subtrochanteric extension patterns.
   • Anticipation of Challenges: Identify potential issues like poor bone quality, severe comminution, or patient-specific anatomical variations.
   • Blood Management: Type and cross-match blood products are often indicated due to potential significant blood loss.

Patient Positioning

• General Considerations:
  • Positioning must allow for adequate imaging (AP and lateral fluoroscopy).
  • Maintain patient comfort and prevent pressure sores, especially in elderly patients.
  • Ensure appropriate padding of bony prominences and nerve bundles.
• Supine on a Fracture Table:
  • This is the standard position for nearly all proximal femur fracture fixations.
  • The uninjured leg is abducted, flexed, and placed in a well-padded boot, allowing for lateral C-arm access.
  • The injured leg is placed in traction, typically with an ankle boot, to facilitate reduction maneuvers.
  • Careful padding of the perineum, sacrum, and contralateral extremity is essential.
  • The patient's torso is often shifted slightly to the contralateral side to ensure unobstructed access to the hip.
  • Reduction Maneuvers: Manual traction, internal rotation, and slight abduction are common. For intertrochanteric fractures, precise rotation is critical to restore the neck-shaft angle and anteversion. For femoral neck fractures, reduction is often achieved with traction, internal rotation, and slight abduction.
  • C-arm Positioning: The C-arm must be able to obtain true AP and lateral views of the proximal femur without repositioning the patient. The non-injured leg being flexed allows the C-arm to swing between the legs for lateral views.

Detailed Surgical Approach / Technique

The choice of surgical technique is dictated by fracture morphology (femoral neck vs. intertrochanteric), patient factors, and surgeon preference.

Femoral Neck Fractures

1. Internal Fixation (Cannulated Screws)

• Indications: Undisplaced or minimally displaced femoral neck fractures (Garden I, II), physiologically younger patients (often <60-70 years old) with displaced fractures (controversial, high risk of ONFH/non-union).
• Approach: Antero-lateral or direct lateral incision.
• Reduction: Critical for success. Achieved by gentle traction, internal rotation, and slight abduction of the leg on the fracture table. Fluoroscopic guidance ensures anatomical alignment in both AP and lateral planes (neutral or slight valgus reduction is desired). Excessive varus or malrotation increases risk of non-union.
• Fixation: Typically three parallel cannulated screws, 6.5 mm or 7.3 mm in diameter.
  • Guide Wire Placement: Insert the first guide wire centrally in the femoral neck on the AP view and inferiorly/posteriorly on the lateral view. This ensures optimal purchase in the calcar and avoids damage to superior retinacular vessels.
  • The second guide wire is placed superior to the first on the AP view, parallel, and slightly anterior on the lateral view.
  • The third guide wire is placed inferior to the first on the AP view, parallel, and slightly anterior on the lateral view. The screws form a "triangle" or "inverted triangle" configuration.
  • Screw Length & Depth: Screws should be as long as possible, extending just subchondrally into the femoral head to maximize purchase without penetrating the articular cartilage.
  • Compression: Screws are typically partially threaded to allow for compression across the fracture site.

2. Arthroplasty (Hemiarthroplasty or Total Hip Arthroplasty)

• Indications:
  • Hemiarthroplasty: Displaced femoral neck fractures in elderly, less active patients, or those with comorbidities making THA less suitable. Unipolar or bipolar prostheses.
  • Total Hip Arthroplasty (THA): Displaced femoral neck fractures in physiologically younger, active elderly patients, or those with pre-existing symptomatic hip osteoarthritis.
• Approach:
  • Posterior (Kocher-Langenbeck): Most common for hemiarthroplasty and THA for fracture. Provides excellent visualization of the posterior hip structures and allows for capsulectomy.
    • Internervous Plane: Between gluteus maximus (innervated by inferior gluteal nerve) and tensor fascia lata/gluteus medius (innervated by superior gluteal nerve). The gluteus maximus is split, and the short external rotators (piriformis, gemelli, obturator internus, quadratus femoris) are detached from their insertions on the greater trochanter.
    • Dissection: Skin incision from greater trochanter towards posterior superior iliac spine. Fascia lata incised, gluteus maximus fibers split. Deep dissection identifies the short external rotators, which are released. The hip capsule is then identified and incised (capsulotomy). The femoral head is dislocated and extracted.
  • Anterolateral (Hardinge): Offers preservation of posterior soft tissues.
  • Direct Anterior Approach (DAA): Gaining popularity, but more technically demanding for trauma.
• Technique:
  • Femoral Preparation: Reaming of the femoral canal, broaching to determine stem size, and cementation (if cemented stem) or press-fit (if uncemented stem).
  • Acetabular Preparation (for THA): Reaming of the acetabulum, press-fit or cemented acetabular component insertion, then liner insertion.
  • Head Implantation: Selection of appropriate head size and neck length.
  • Reduction and Stability Testing: Hip is reduced, and stability is assessed through range of motion.
  • Closure: Repair of capsule and external rotators (for posterior approach) or vastus lateralis (for anterolateral approach). Layered closure.

Intertrochanteric Fractures

1. Sliding Hip Screw (DHS - Dynamic Hip Screw)

• Indications: Stable intertrochanteric fractures (e.g., two-part, non-comminuted posteromedial cortex).
• Approach: Direct lateral approach, typically 10-15 cm incision centered over the greater trochanter.
• Reduction: Achieved on the fracture table with traction, internal rotation, and adduction. Fluoroscopic confirmation of anatomical or slightly valgus reduction (critical for load sharing).
• Technique:
  • Guide Wire Placement: Insert a guide wire into the center of the femoral head on both AP and lateral views. It should ideally be 5-10 mm from the subchondral bone. Tip-Apex Distance (TAD) should be <25 mm for optimal screw placement.
  • Reaming: Ream over the guide wire to the appropriate depth for the lag screw.
  • Lag Screw Insertion: Insert the cannulated lag screw, ensuring it is flush with the lateral cortex.
  • Plate Application: Apply the side plate to the lateral femoral cortex, ensuring proper alignment with the lag screw barrel. Secure with cortical screws.
  • Compression: Dynamize the system by allowing the lag screw to slide within the barrel, enabling controlled collapse at the fracture site under weight-bearing.

2. Intramedullary Nailing (Cephalomedullary Nail)

• Indications: Unstable intertrochanteric fractures (e.g., comminuted, reverse obliquity, subtrochanteric extension). Gaining favor even for stable patterns due to biomechanical advantages and smaller incision.
• Approach: Small incision (~5 cm) over the tip of the greater trochanter.
• Reduction: Similar to DHS, on fracture table. Excellent reduction is crucial.
• Technique:
  • Entry Point: Critical for avoiding varus malalignment. Located at or just medial to the tip of the greater trochanter, in line with the femoral shaft axis on AP view.
  • Reaming/Broaching: Ream the canal to the appropriate size for the intramedullary nail.
  • Nail Insertion: Insert the cephalomedullary nail, ensuring it passes the fracture site.
  • Lag Screw/Blade Insertion: Under fluoroscopic guidance, insert one or two cephalic screws/blades into the femoral head, aiming for optimal placement (center-center in AP, center-inferior in lateral, TAD <25 mm).
  • Distal Locking: Apply distal locking screws to prevent rotation and maintain length. Unicortical or bicortical options depending on nail design.
  • Compression: Many nails allow for controlled compression across the fracture site.
  • Closure: Layered closure.

Complications & Management

Proximal femur fractures carry a significant risk of complications, impacting patient recovery and long-term outcomes. Proactive identification and management are crucial.

Common Complications

| Complication | Incidence | Salvage Strategies / Management |
| Mortality (1-year) | ~14-36% | Affects overall prognosis, though immediate cause is often comorbidity related. |
| Pressure Sores | 5-20% | Prevention: Early mobilization, frequent turning, adequate nutrition, pressure-relieving mattresses. Management: Wound care, debridement, antibiotics for infection, surgical flaps in severe cases. |
| Deep Vein Thrombosis (DVT) & Pulmonary Embolism (PE) | DVT: 10-60% (clinical), PE: 0.5-10% | Prevention: Mechanical prophylaxis (compression stockings, intermittent pneumatic compression devices), chemical prophylaxis (LMWH, fondaparinux) starting pre-op or early post-op. Management: Anticoagulation (therapeutic), thrombolysis or embolectomy for massive PE. |
| Pneumonia | 10-20% | Prevention: Early mobilization, incentive spirometry, chest physiotherapy, adequate pain control. Management: Antibiotics, respiratory support. |
| Urinary Tract Infection (UTI) | 5-15% | Prevention: Early Foley catheter removal, good perineal hygiene. Management: Antibiotics based on culture. |
| Delirium | 10-50% | Prevention: Early mobilization, pain control, sleep hygiene, minimizing polypharmacy, addressing sensory deficits. Management: Identify and treat underlying cause, supportive care, medication adjustment, sometimes judicious use of antipsychotics. |
| Non-union (Femoral Neck) | 10-30% | Management: Arthroplasty (hemi or THA) for symptomatic non-union, especially in older patients. ORIF with bone grafting in select younger patients. |
| Avascular Necrosis (AVN) of Femoral Head (Femoral Neck) | 10-40% (displaced) | Management: Core decompression or vascularized fibular graft in early stages for younger patients; Arthroplasty (hemi or THA) for symptomatic AVN with collapse in older patients. |
| Cut-out / Loss of Fixation (Intertrochanteric) | 5-15% | Management: Revision surgery with a more stable implant (e.g., conversion from DHS to IMN, or revision IMN), possibly with augmentation (bone graft, cement). Arthroplasty as salvage for failed fixation. |
| Malunion | Varies | Management: Corrective osteotomy for symptomatic malunion (e.g., significant varus, shortening, rotational deformity) in younger, active patients. Conservative management for asymptomatic malunion. Arthroplasty if malunion leads to severe arthritis. |
| Infection (SSI) | 1-5% | Prevention: Perioperative antibiotics, sterile technique, careful wound handling. Management: Debridement, irrigation, antibiotics (IV then oral), implant retention vs. removal (depending on type/severity/timing). For chronic infection, staged revision arthroplasty (for THA) or excision arthroplasty. |
| Peri-prosthetic Fracture (Arthroplasty) | 1-2% | Management: Based on Vancouver classification. ORIF, revision arthroplasty, or combination, depending on fracture location, stability of components, and bone stock. |

Post-Operative Rehabilitation Protocols

Post-operative rehabilitation is integral to regaining function and preventing secondary complications. Protocols are individualized but follow general principles.

Immediate Post-Operative Phase (Days 0-7)

• Pain Management: Multimodal approach (opioids, NSAIDs, acetaminophen, nerve blocks) to facilitate early mobilization.
• Weight-Bearing Status:
  • Femoral Neck (Cannulated Screws): Typically partial weight-bearing (PWB) or touch-down weight-bearing (TDWB) initially, progressing to full weight-bearing (FWB) over 6-12 weeks, depending on fracture stability, bone quality, and surgeon preference.
  • Arthroplasty (Hemi/THA): FWB as tolerated immediately post-op, unless there are specific stability concerns (e.g., soft tissue repair, peri-prosthetic fracture).
  • Intertrochanteric (DHS/IMN): FWB as tolerated immediately post-op, given stable fixation. PWB may be indicated for severely comminuted or reverse oblique fractures.
• Mobilization: Out of bed to a chair within 24 hours. Early ambulation with appropriate assistive devices (walker, crutches).
• Physical Therapy (PT):
  • Range of Motion (ROM): Gentle active and passive ROM exercises within prescribed limits.
  • Strengthening: Isometric quadriceps and gluteal sets.
  • Transfers: Practice bed-to-chair, toilet transfers.
  • Gait Training: Focus on proper weight-bearing and gait mechanics.
• Occupational Therapy (OT): Assessment for activities of daily living (ADLs), adaptive equipment, and home safety modifications.
• DVT/PE Prophylaxis: Continued as per institutional protocol.

Early Rehabilitation Phase (Weeks 1-6)

• Progression of Weight-Bearing: Gradual increase in weight-bearing and reduction of assistive device reliance as pain subsides and muscle strength improves.
• PT Focus:
  • Strengthening: Progressive resistive exercises for hip abductors, adductors, flexors, and extensors. Knee and ankle strengthening.
  • Balance and Proprioception: Standing balance exercises, single-leg stance.
  • Gait Training: Improvement of gait pattern, step length, and speed.
  • Functional Activities: Stair climbing, negotiating uneven surfaces.
• Arthroplasty Precautions: Patients undergoing THA via a posterior approach may have hip precautions (no hip flexion >90 degrees, no adduction past midline, no internal rotation) for 6-12 weeks to minimize dislocation risk. Newer approaches or stable repairs may allow for fewer restrictions.

Advanced Rehabilitation Phase (Weeks 6-12+)

• Independence: Aim for independent ambulation without assistive devices, or with a single cane.
• PT Focus:
  • High-level Strengthening: Closed-chain exercises, functional strengthening specific to patient's pre-injury activity level.
  • Endurance Training: Walking, stationary bike.
  • Return to Activity: Gradually resume pre-injury activities, with guidance from the therapist and surgeon.
• Bone Health: Continue osteoporosis management with calcium, Vitamin D, and anti-resorptive medications as indicated.
• Long-term Monitoring: Regular follow-up with the surgeon to monitor implant integrity, bone healing, and functional recovery.

Summary of Key Literature / Guidelines

Evidence-based guidelines inform the contemporary management of proximal femur fractures, emphasizing early intervention and patient-specific strategies.

Femoral Neck Fractures

• Displaced Femoral Neck Fractures in Elderly: Multiple randomized controlled trials (RCTs) and meta-analyses consistently demonstrate superior outcomes (lower reoperation rates, better functional scores) with arthroplasty (hemiarthroplasty or THA) compared to internal fixation.
  • Hemiarthroplasty vs. THA: For active, physiologically younger elderly patients with good bone quality and pre-existing osteoarthritis, THA often yields better functional outcomes and lower revision rates for acetabular pain/erosion, but carries a slightly higher risk of dislocation. For less active or frail patients, hemiarthroplasty is a reasonable choice.
  • FAITH Trial (Fixation or Arthroplasty for Intertrochanteric Hip fractures): While specifically for intertrochanteric fractures, it underscored the complexity of decision-making. More relevantly, studies like the HEALTH trial (Hip Fracture Evaluation with Alternative Treatments and Outcomes Study) for displaced femoral neck fractures in the elderly randomized patients to THA or hemiarthroplasty, showing comparable mortality, but THA had lower reoperation rates for hip-related issues, albeit with a higher dislocation rate.
• Undisplaced Femoral Neck Fractures: Internal fixation (typically multiple cannulated screws) remains the gold standard. The risk of secondary displacement and non-union, while lower than for displaced fractures, necessitates careful patient selection and precise surgical technique.

Intertrochanteric Fractures

• Sliding Hip Screw (DHS) vs. Intramedullary Nail (IMN):
  • Stable Fractures: Both DHS and IMN are effective. Meta-analyses suggest similar rates of union and mortality. DHS may have a slightly higher rate of blood loss and wound complications, while IMN may have a slightly higher risk of distal locking screw complications or anterior knee pain.
  • Unstable Fractures (AO/OTA 31-A2, A3; reverse obliquity): Intramedullary nailing has demonstrated superior biomechanical stability and lower rates of implant failure (cut-out, non-union, varus collapse) compared to DHS. This is due to the central load-sharing capacity of the nail, reducing bending moments at the fracture site.
  • Subtrochanteric Extension: IMN is the preferred implant for fractures extending into the subtrochanteric region due to better control of the distal fragment and load-sharing capabilities.
• Geriatric Trauma and Fragility Fractures:
  • Early Surgery: Numerous studies advocate for surgery within 24-48 hours of admission to reduce morbidity and mortality, particularly for complications like pneumonia, pressure ulcers, and delirium.
  • Multidisciplinary Approach: Collaboration between orthopedic surgeons, geriatricians, anesthesiologists, and rehabilitation specialists is strongly recommended to optimize medical management, surgical timing, and post-operative recovery pathways.
  • Osteoporosis Management: Guidelines emphasize the critical importance of evaluating and treating underlying osteoporosis in all fragility fracture patients to prevent subsequent fractures. This includes pharmacotherapy (bisphosphonates, denosumab, teriparatide) and lifestyle modifications.

General Guidelines

• Perioperative Medical Optimization: Guidelines from organizations like the American Academy of Orthopaedic Surgeons (AAOS) and the National Institute for Health and Care Excellence (NICE) consistently highlight the importance of aggressive medical optimization, pain control, and DVT prophylaxis.
• Rehabilitation: Early mobilization and structured rehabilitation protocols are universally endorsed to maximize functional recovery and minimize complications of immobility.

The mastery of these guidelines, informed by rigorous data ("containers" of clinical evidence), is fundamental to providing optimal care for patients with proximal femur fractures.