Can heterotropic ossification (HO) after hip surgery cause pain?

Heterotopic Ossification After Hip Surgery Can Cause Pain

Yes, heterotopic ossification (HO) after hip surgery can cause significant pain and limited range of motion, potentially requiring surgical excision in severe cases. 1 Heterotopic ossification is a known complication following total hip arthroplasty that can become symptomatic with pain and functional limitations.

What is Heterotopic Ossification?

Heterotopic ossification is the abnormal formation of bone in soft tissues where bone normally doesn't exist. After hip surgery, this can occur in the surrounding muscles and soft tissues.

Incidence and Risk Factors

• Occurs in approximately 10-40% of patients after total hip arthroplasty 2
• More common with certain surgical approaches:
  • Historically associated with posterolateral approach
  • Also occurs with direct anterior or anterior-based muscle sparing approaches 2
• Higher risk in:
  • Male patients (especially those with higher BMI) 3
  • Patients with ASA grade >3 3
  • Older women 3
  • Patients with extensive soft tissue trauma during surgery 4

Clinical Presentation

• Pain around the hip joint
• Limited range of motion
• Stiffness
• In severe cases (Brooker grade 4), significant functional impairment 3

Diagnosis

Radiographs are usually the first imaging modality for assessment of a symptomatic hip prosthesis 5. They can help identify:

• Heterotopic ossification
• Periprosthetic fractures
• Avulsions of the greater trochanter 5

Impact on Patient Outcomes

• Low-grade HO (Brooker grades 0-3) typically does not significantly impact patient-reported outcomes 3
• Only severe HO (Brooker grade 4) is associated with significantly worse patient-reported outcomes, though interestingly, pain may not be affected in all cases 3
• Additional radiographic views may be necessary, as lateral views can detect 9% additional HO compared to anteroposterior views alone 3

Prevention Strategies

• NSAIDs are commonly used for prophylaxis:
  • 87% of surveyed departments in Germany administer NSAIDs for approximately 3 weeks after surgery 4
  • The ASAS/EULAR guidelines note that NSAID treatment does not need to be discontinued for THA surgery 5
• Low-dose radiation therapy:
  • Used in 64% of trauma/orthopedic departments for high-risk patients 4
  • Mean dosage of 7 Gy 4
• Surgical technique considerations:
  • Transverse "bikini" incision is associated with lower rates (4%) of severe HO compared to longitudinal incision (12%) 3

Treatment of Symptomatic HO

• For mild to moderate cases: physical therapy and pain management
• For severe cases with significant pain and limited motion:
  • Surgical excision may be required 1
  • Excision should be planned carefully with appropriate preoperative planning and intraoperative fluoroscopic guidance 1
  • Postoperative HO prophylaxis and immediate mobilization are important to prevent recurrence 1
  • Significant blood loss can occur during surgery and should be anticipated 1

Outcomes After Treatment

Surgical excision of symptomatic HO in a preserved hip joint can successfully restore hip range of motion and function when combined with appropriate postoperative prophylaxis 1.

Monitoring

Regular assessment of pain levels and functional outcomes should be conducted using validated instruments such as the Harris Hip Score, WOMAC, or SF-36 6.

Heterotopic ossification represents an important potential complication after hip surgery that clinicians should monitor for, particularly in high-risk patients. Early identification and appropriate management can help minimize its impact on patient outcomes.