Heterotopic Ossification after Arthroscopy for Hip Impingement Syndrome

Heterotopic Ossification after Arthroscopy for Hip Impingement Syndrome

Introduction
Heterotopic ossification (HO) is the abnormal formation of bone in non-skeletal tissues, such as muscles and articular capsules, often resulting from changes in osteogenesis regulation mechanisms. It is a well-documented complication following hip surgery, with reported incidences as high as 44% in patients without preventative measures. HO can range from minor ossifications to extensive bone deposition, potentially causing pain, impingement, and reduced range of motion, which may necessitate surgical intervention.

HO is particularly associated with open hip surgeries, including total hip replacement, open reduction, and internal fixation of hip fractures. However, it is also observed after hip arthroscopy, a minimally invasive procedure increasingly used for treating femoroacetabular impingement (FAI). This study investigates the incidence of HO after hip arthroscopy for FAI and evaluates the outcomes of revision surgery for HO resection.

Methods
A retrospective analysis was conducted on 242 patients (140 men and 102 women, mean age 36.2±9.5 years) who underwent hip arthroscopy for FAI between January 2016 and January 2018. The average follow-up period was 22.88±11.74 months (range: 11–34 months). Among these patients, 13 (5.37%) developed HO, with four undergoing revision surgery due to persistent pain and functional limitations.

Patients were excluded if pre-operative imaging showed evidence of HO. Post-operative evaluations included monthly follow-ups using the Visual Analog Scale (VAS), modified Harris Hip Score (mHHS), and Non-Arthritis Hip Score (NAHS). HO was classified using the Brooker classification system, and imaging modalities such as radiography, computed tomography (CT), and ultrasonography were employed for diagnosis.

Ultrasonography was performed by experienced musculoskeletal specialists, who identified HO as early as three weeks post-operation. Revision surgery involved arthroscopic removal of HO, with patients receiving 60 mg etoricoxib daily for six weeks post-operatively to prevent recurrence.

Results
Of the 242 patients, 13 (5.4%) developed HO, with nine classified as Brooker stage I, three as stage II, and one as stage III. HO was detected via ultrasonography as early as three weeks post-surgery. Functional outcomes were compared between HO and non-HO groups. The mHHS increased by 13.00 points in the HO group and 24.00 points in the non-HO group, while the NAHS increased by 18.00 and 26.00 points, respectively. The VAS decreased by 3.00 points in the HO group and 4.00 points in the non-HO group, with no significant differences observed between the groups.

Four patients underwent revision surgery for HO resection due to persistent pain. Post-revision, the mHHS increased by 34.75 points, the NAHS by 28.75 points, and the VAS decreased by 4 points, indicating significant improvements in pain and function. Patient satisfaction scores averaged 8.46 out of 10.

Discussion
The incidence of HO after hip arthroscopy for FAI in this study (5.37%) is consistent with previous reports, which range from 1% to 11.4%. This is notably lower than the incidence following open hip surgeries, likely due to the minimally invasive nature of arthroscopy, which reduces trauma and bleeding, and the continuous irrigation of bone debris during the procedure.

Ultrasonography proved to be a valuable tool for early HO detection, identifying ossifications as early as three weeks post-operation. This modality offers advantages over radiography, CT, and MRI, including cost-effectiveness, portability, and the absence of radiation exposure. However, its effectiveness depends on the expertise of the ultrasonographer.

Prevention of HO remains a critical consideration. Non-steroidal anti-inflammatory drugs (NSAIDs), particularly selective COX-2 inhibitors, have shown efficacy in reducing HO incidence. In this study, patients who underwent revision surgery received etoricoxib for six weeks post-operatively, which may have contributed to the absence of recurrence.

The clinical impact of HO varies, with most cases being asymptomatic and not requiring intervention. However, patients with persistent pain or functional limitations may benefit from revision surgery. In this study, all four patients who underwent HO resection experienced significant improvements in pain and function, with high satisfaction scores.

Conclusion
This study highlights that the incidence of HO after hip arthroscopy for FAI is relatively low compared to open hip surgeries. Most cases of HO are asymptomatic and do not require surgical intervention. However, patients with persistent pain or functional limitations may benefit from revision surgery, which can significantly improve outcomes.

Ultrasonography is a sensitive and effective tool for early HO detection, offering advantages over traditional imaging modalities. Prophylactic measures, such as NSAIDs, can reduce the risk of HO formation. Overall, arthroscopic HO resection is a viable option for symptomatic patients, leading to improved pain relief and joint function.

doi.org/10.1097/CM9.0000000000000153

Was this helpful?

YesNo

0 / 0