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Subcapital fracture of neck of femur — Clinical Guidelines

Overview

Subcapital fractures of the neck of femur, also known as femoral neck fractures, are common orthopaedic injuries predominantly affecting older adults due to factors such as osteoporosis and falls. These fractures are clinically significant due to their potential to severely impair mobility and quality of life, often necessitating surgical intervention. They are particularly prevalent in populations with decreased bone density and compromised bone quality, leading to high rates of complications including avascular necrosis, nonunion, and the need for revision surgery. Understanding optimal management strategies is crucial in day-to-day practice to minimize morbidity and maximize functional outcomes for patients 1 4 8.

Pathophysiology

Subcapital femoral neck fractures typically result from low-energy trauma in elderly individuals, often due to falls from standing height, exacerbated by underlying bone fragility. The mechanism involves excessive stress on the femoral neck, leading to failure at the weakest point, usually where the trabecular bone is thinnest. This mechanical failure can disrupt blood supply to the femoral head, particularly in displaced fractures, leading to avascular necrosis and subsequent collapse 8. Additionally, the presence of comorbidities like diabetes and renal insufficiency can further compromise healing and increase the risk of complications such as infection and nonunion 4.

Epidemiology

Femoral neck fractures predominantly affect individuals over 65 years of age, with a higher incidence in women due to postmenopausal osteoporosis. The incidence rates vary geographically but generally show an increasing trend with aging populations. Risk factors include advanced age, female gender, history of falls, and underlying bone diseases like osteoporosis. Recent studies suggest that despite demographic shifts towards more active elderly populations, the overall incidence remains high, emphasizing the ongoing clinical challenge 1 4.

Clinical Presentation

Patients typically present with acute hip pain following a fall, often unable to bear weight on the affected limb. Common symptoms include pain radiating down the thigh, shortening, and external rotation of the limb (the "frozen hip" sign). Red-flag features include severe pain disproportionate to the mechanism of injury, signs of neurovascular compromise, and inability to ambulate post-injury. Prompt recognition of these features is crucial for timely intervention 8.

Diagnosis

The diagnosis of subcapital femoral neck fractures involves a combination of clinical assessment and imaging. Diagnostic Approach:

Clinical Examination: Focus on pain, range of motion, and signs of neurovascular compromise.

Imaging: X-rays are the primary modality, with anteroposterior and frog-leg views essential for accurate assessment. CT and MRI may be used to further delineate fracture patterns and assess soft tissue injuries when necessary.

Specific Criteria and Tests:

X-ray Findings: Presence of fracture line across the femoral neck, displacement, and associated subluxation or dislocation.

CT/MRI: For detailed fracture characterization and assessment of soft tissue injuries (when indicated).

Differential Diagnosis: Avascular necrosis, hip dislocations, stress fractures, and inflammatory arthropathies can mimic femoral neck fractures but are typically distinguished by specific imaging features and clinical context 1 2 8.

Management

Initial Management

Stabilization: Immobilize the affected limb to prevent further displacement and ensure patient comfort.

Pain Control: Administer analgesics (e.g., NSAIDs or opioids) as needed for pain management.

Hemodynamic Stability: Monitor and stabilize vital signs, especially in elderly patients.

Surgical Interventions

First-Line Treatments:

Internal Fixation: Suitable for stable, nondisplaced fractures or younger patients with good bone quality. Techniques include cannulated screws, dynamic hip screw (DHS), and plates.

- Specifics: Cannulated screws (e.g., 4.5 mm screws), DHS with side plate, careful reduction and stabilization. - Contraindications: Severe osteoporosis, significant displacement, or compromised vascular supply 2 3.

Second-Line Treatments:

Hemiarthroplasty: Preferred for displaced fractures in elderly patients or those with poor bone quality.

- Specifics: Use of cemented or cementless bipolar or unipolar hemiarthroplasties. - Contraindications: Active infection, severe coxarthrosis requiring THA 3 4.

Total Hip Arthroplasty (THA): Recommended for displaced fractures in functionally independent patients without significant comorbidities.

- Specifics: Cemented or cementless THA with appropriate implant selection based on patient anatomy. - Contraindications: Severe cognitive impairment, limited life expectancy, or significant medical comorbidities 4 9.

Refractory Cases

Referral to Orthopaedic Trauma Specialist: For complex fractures, nonunions, or recurrent dislocations.

Multidisciplinary Approach: Involvement of geriatricians, physiotherapists, and pain management specialists for comprehensive care.

Complications

Avascular Necrosis: Risk increases with displacement and time to surgery; managed with close monitoring and potential revision surgery.

Nonunion: Common in unstable fractures; treated with revision fixation or arthroplasty.

Infection: Requires prompt diagnosis and aggressive antibiotic therapy; surgical debridement may be necessary.

Dislocation: Higher risk post-hemiarthroplasty; managed with early physiotherapy and surgical intervention if recurrent.

Referral Triggers: Persistent pain, signs of infection, nonunion, or recurrent dislocation warrant specialist referral 1 2 3 4.

Prognosis & Follow-up

The prognosis for subcapital femoral neck fractures varies based on patient age, fracture displacement, and treatment modality. Prognostic indicators include early surgical intervention, appropriate fixation technique, and absence of complications. Recommended follow-up intervals include:

Immediate Post-Op: Weekly for the first month to monitor healing and detect early complications.

3-6 Months: Assess functional recovery and radiographic union.

Annually: Long-term follow-up to evaluate implant function and patient mobility 4 5.

Special Populations

Elderly Patients: THA or hemiarthroplasty are favored due to lower complication rates and better functional outcomes compared to internal fixation.

Young Patients: Internal fixation with screws or DHS is preferred to preserve femoral head integrity, though outcomes can be challenging due to higher risks of nonunion and avascular necrosis 8.

Comorbidities: Patients with diabetes or renal insufficiency require meticulous perioperative management to reduce infection risk and optimize healing 4.

Key Recommendations

Surgical Intervention Timing: Operate within 24-48 hours for displaced fractures to minimize avascular necrosis risk (Evidence: Strong 4).

Choice of Implant: For displaced fractures in functionally independent elderly patients, THA is recommended over hemiarthroplasty for better long-term outcomes (Evidence: Moderate 4 5).

Avoid Modular Femoral Stems: Given higher revision rates, prefer non-modular stems in primary THA to reduce the risk of modular neck fractures (Evidence: Moderate 1 6).

Multidisciplinary Care: Involve geriatricians and physiotherapists in the management plan to optimize functional recovery (Evidence: Expert opinion 4).

Close Monitoring Post-Op: Regular follow-up within the first month post-surgery to detect and manage complications early (Evidence: Moderate 4).

Patient Selection for THA: Consider THA in younger, active patients with displaced fractures who have reasonable life expectancy and functional demands (Evidence: Moderate 9).

Preoperative Risk Assessment: Evaluate comorbidities such as diabetes and renal insufficiency to tailor perioperative management (Evidence: Moderate 4).

Avoid Metal-on-Metal Resurfacing in High-Risk Patients: Given the risk of late femoral neck fractures, carefully select patients for metal-on-metal resurfacing (Evidence: Weak 10).

Use of CT/MRI: Employ advanced imaging (CT/MRI) when necessary for detailed fracture assessment and soft tissue evaluation (Evidence: Moderate 2).

Pain Management Protocol: Implement a multimodal pain management strategy to enhance patient comfort and early mobilization (Evidence: Expert opinion 1).

References

1 Kovač S, Mavčič B, Kotnik M, Levašič V, Sirše M, Fokter SK. What Factors Are Associated With Neck Fracture in One Commonly Used Bimodular THA Design? A Multicenter, Nationwide Study in Slovenia. Clinical orthopaedics and related research 2019. link 2 Obey MR, Falgons CG, Eastman JG, Choo AM, Achor TS, Munz JW et al.. Low reoperation rate after fixation of displaced femoral neck fractures with the femoral neck system (FNS). European journal of orthopaedic surgery & traumatology : orthopedie traumatologie 2024. link 3 Viswanath A, Malik A, Chan W, Klasan A, Walton NP. Treatment of displaced intracapsular fractures of the femoral neck with total hip arthroplasty or hemiarthroplasty. The bone & joint journal 2020. link 4 Hoskins W, Webb D, Bingham R, Pirpiris M, Griffin XL. Evidence based management of intracapsular neck of femur fractures. Hip international : the journal of clinical and experimental research on hip pathology and therapy 2017. link 5 Tol MC, van den Bekerom MP, Sierevelt IN, Hilverdink EF, Raaymakers EL, Goslings JC. Hemiarthroplasty or total hip arthroplasty for the treatment of a displaced intracapsular fracture in active elderly patients: 12-year follow-up of randomised trial. The bone & joint journal 2017. link 6 Krishnan H, Krishnan SP, Blunn G, Skinner JA, Hart AJ. Modular neck femoral stems. The bone & joint journal 2013. link 7 Stoffel KK, Nivbrant B, Headford J, Nicholls RL, Yates PJ. Does a bipolar hemiprosthesis offer advantages for elderly patients with neck of femur fracture? A clinical trial with 261 patients. ANZ journal of surgery 2013. link 8 Davidovitch RI, Jordan CJ, Egol KA, Vrahas MS. Challenges in the treatment of femoral neck fractures in the nonelderly adult. The Journal of trauma 2010. link 9 Schmidt AH, Leighton R, Parvizi J, Sems A, Berry DJ. Optimal arthroplasty for femoral neck fractures: is total hip arthroplasty the answer?. Journal of orthopaedic trauma 2009. link 10 Sharma H, Rana B, Watson C, Campbell AC, Singh BJ. Femoral neck fractures complicating metal-on-metal resurfaced hips: a report of 2 cases. Journal of orthopaedic surgery (Hong Kong) 2005. link

Subcapital fracture of neck of femur