M84.750K Atypical femoral fracture, unspecified, subsequent encounter for fracture with nonunion

Name of the Condition

• Atypical Femoral Fracture, Unspecified, Subsequent Encounter for Fracture with Nonunion (ICD-10-CM: M84.750K)

Summary

This condition represents a specific type of femoral fracture that occurs with minimal or no trauma, typically in the subtrochanteric or diaphyseal region. The "subsequent encounter" designation indicates ongoing care after the initial fracture event, and "nonunion" signifies that the fracture has failed to heal properly within the expected timeframe. These fractures are often associated with underlying bone fragility, such as from long-term bisphosphonate use, and may present with persistent pain or functional impairment.

Causes

Atypical femoral fractures result from impaired bone remodeling, often linked to prolonged bisphosphonate therapy or other antiresorptive medications. The exact mechanism involves reduced bone turnover, leading to increased brittleness and a higher risk of incomplete or complete fractures. Other contributing factors include metabolic bone disorders, vitamin D deficiency, or conditions that compromise bone quality, even without significant trauma.

Risk Factors

• Long-term bisphosphonate or antiresorptive therapy
• Advanced age
• Low bone mineral density or osteoporosis
• History of prior atypical fractures
• Chronic glucocorticoid use
• Vitamin D or calcium deficiency

Symptoms

• Persistent thigh or groin pain, often worsening with activity
• Difficulty bearing weight or walking
• Possible swelling or tenderness at the fracture site
• Visible deformity if a complete fracture has occurred
• Lack of healing progress over time (nonunion)

Diagnosis

Diagnosis requires a combination of clinical evaluation, patient history (including medication use), and imaging studies. X-rays or MRI may reveal characteristic features of atypical femoral fractures, such as transverse patterns or cortical thickening. Bone density testing or metabolic workups may be performed to assess underlying bone health. The "nonunion" designation is confirmed when imaging shows no evidence of progressive healing after an appropriate period.

Treatment Options

Treatment focuses on promoting fracture healing and addressing underlying bone fragility. Options may include discontinuing or modifying antiresorptive therapy, surgical intervention (e.g., intramedullary nailing), bone-stimulating devices, or nutritional supplementation (e.g., vitamin D, calcium). Physical therapy and activity modification are often recommended to support recovery and prevent further injury.

Prognosis and Follow-Up

Prognosis depends on the severity of the fracture, adherence to treatment, and resolution of nonunion. With appropriate management, many patients achieve healing and restored function, though recovery may be prolonged. Regular follow-up with imaging and clinical assessments is essential to monitor healing progress and adjust treatment as needed.

Complications

• Persistent nonunion or delayed healing
• Infection at the fracture site
• Malunion or deformity
• Reduced mobility or functional impairment
• Increased risk of future fractures

Lifestyle & Prevention

• Maintain adequate vitamin D and calcium intake
• Engage in weight-bearing exercises to support bone health
• Avoid high-impact activities that may stress the femur
• Discuss medication risks with healthcare providers, especially if on long-term bisphosphonates
• Monitor for early symptoms (e.g., thigh pain) and seek prompt evaluation

When to Seek Professional Help

Seek immediate medical attention if you experience sudden, severe thigh pain, inability to bear weight, or visible deformity. For persistent pain or concerns about healing, consult a healthcare provider to assess for nonunion or other complications.

Tips for Medical Coders

Document the encounter type (subsequent) and confirm the presence of nonunion to support the M84.750K code. Include details about fracture location, treatment provided, and any underlying bone fragility factors. Ensure clinical documentation aligns with the "subsequent encounter for fracture with nonunion" definition to accurately reflect the patient’s status.