Prophylactic radiotherapy against heterotopic ossification following internal fixation of acetabular fractures: a comparative estimate of risk

Heterotopic Ossification Remodeling After Acetabular Surgery: A Natural History Case Report

CASE

A 30-year-old woman presented with a transverse plus posterior wall acetabular fracture and underwent operative fixation through a Kocher-Langenbeck approach. Shared decision was made for no heterotopic ossification (HO) prophylaxis. The patient developed symptomatic HO and was scheduled for resection, which was delayed because of the pandemic. She returned with interval remodeling of HO and symptom resolution. No surgery was required.

CONCLUSION

HO is a common complication after acetabular injury. Resection is the treatment of choice for symptomatic HO. We are not aware of other reports of spontaneous remodeling of symptomatic HO such that it no longer required surgery.

The impact of heterotopic ossification prophylaxis after surgical fixation of acetabular fractures: national treatment patterns and related outcomes

BACKGROUND

Heterotopic ossification (HO) is a common complication after surgical fixation of acetabular fractures. Numerous strategies have been employed to prevent HO formation, but results are mixed and optimal treatment strategy remains controversial. The purpose of the study was to describe current national heterotopic ossification (HO) prophylaxis patterns among academic trauma centers, determine the association between prophylaxis type and radiographic HO, and identify if heterogeneity in treatment effects exist based on outcome risk strata.

METHODS

We used data from a subset of participants enrolled in the Pragmatic Randomized Trial Evaluating Pre-Operative Alcohol Skin Solutions in Fractured Extremities (PREPARE) trial. We included only patients with closed AO-type 62 acetabular fractures that were surgically treated via a posterior (Kocher-Langenbeck), combined anterior and posterior, or extensile exposure. PREPARE Clinical Trial Registration Number: NCT03523962 Patient population This cohort study was nested within the Pragmatic Randomized Trial Evaluating Pre-Operative Alcohol Skin Solutions in Fractured Extremities (PREPARE) trial. The PREPARE trial is a multicenter cluster-randomized crossover trial evaluating the effectiveness of two alcohol-based pre-operative antiseptic skin solutions. All PREPARE trial clinical centers that enrolled at least one patient with a closed AO-type 62 acetabular fracture were invited to participate in the nested study.

RESULTS

277 patients from 20 level 1 and level 2 trauma centers in the U.S. and Canada were included in this study. 32 patients (12%) received indomethacin prophylaxis, 100 patients (36%) received XRT prophylaxis, and 145 patients (52%) received no prophylaxis. Administration of XRT was associated with a 68% reduction in the adjusted odds of overall HO (OR 0.32, 95% CI, 0.14 - 0.69, p = 0.005). The overall severe HO (Brooker classes III or IV) rate was 8% for the entire cohort; XRT reduced the rate of severe HO in high-risk patients only (p=0.03).

CONCLUSION

HO prophylaxis patterns after surgical fixation of acetabular fractures have changed dramatically over the last two decades. Most centers included in this study did not administer HO prophylaxis. XRT was associated with a marked reduction in the rate of overall HO and the rate of severe HO in high-risk patients. Randomized trials are needed to fully elucidate the potential benefit of XRT. PREPARE Clinical Trial Registration Number: NCT03523962.

Fifteen years’ experience of radiation therapy for resected advanced heterotopic ossification following motor vehicle accidents: outcome and side effects

Background

Surgical resection is the primary treatment for advanced-stage heterotopic ossification (HO), with a high incidence of local recurrence reaching up to 50%. Postoperative radiotherapy (PORT) and indomethacin are commonly used prophylactic strategies following surgery. The study aims to assess the safety and effectiveness of PORT in advanced-stage HO patients having motor vehicle accidents (MVA).

Methods

Medical records of patients having HO following MVA between 2006 and 2021 were retrospectively reviewed. Thirty-nine patients with advanced disease (35 had hip HO and 4 had elbow HO) were included in the study.

Results

Excision of HO with joint preservation was performed for 82% of patients, while 18% had a joint replacement. Seven to 8 Gy radiation was given to all patients within 3 days postoperatively. A ninty seven percent of patients regained partially the movement range. The mean follow-up time was 74 months. Six patients had treatment failure, with only one having a recurrence of HO. The 8-year treatment failure-free rate (8-y TFFR) was 79.3±9%, and the 5-year HO failure-free rate (5y-HOFFR) was 97.2±3%. Acute side effects were experienced in 13% of patients but resolved without any consequences. Despite the relatively long follow-up time, we did not report any absolute infertility or secondary malignancies related to the radiation. The testicular mean calculated dose was 33±44 cGy, and the mean measured dose was 58±40 cGy. Of the 35 patients who received radiation to the pelvis, 26 were married, and all did not experience infertility post-treatment.

Conclusion

PORT proved an effective and safe treatment for advanced-stage HO disease. The treatment failure is mainly related to surgical difficulties due to advanced disease. Treatment using a 3-dimensional or intensity-modulated radiation therapy is not associated with serious side effects like second malignancy or absolute infertility.

Risk Factors for the Development of Heterotopic Ossification Following Acetabular Fractures: A Systematic Review

BACKGROUND

Heterotopic ossification (HO) following acetabular fractures is a common complication that may affect clinical outcomes. However, the effects of prophylactic treatment with nonsteroidal anti-inflammatory drugs or radiation therapy remain controversial. While several factors have been related to the development of HO, there is considerable uncertainty regarding their importance or effect size in the setting of acetabular surgery. Therefore, this systematic review aims to summarize the risk factors for HO following the operative fixation of acetabular fractures and clarify their interrelationships.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, PubMed, MEDLINE, Embase, and CINAHL databases were searched from inception to February 2021. Studies that assessed factors related to HO development among patients with operatively repaired acetabular fractures were included. Outcomes were risk factors and their effect size (p values, odds ratios, and 95% confidence intervals).

RESULTS

Twenty-five studies and 1 conference abstract with a total of 3,940 patients were included. The following risk factors for HO were identified. Patient factors were increased body mass index, male sex, and increased age. Injury factors were intensive care unit (ICU) admission and length of stay, non-ICU hospitalization for >10 days, the need for mechanical ventilation for ≥2 days, abdominal and/or chest injuries, the number and type of associated fractures, traumatic brain injuries, T-type acetabular fractures, pelvic ring injuries, and hip dislocation. Care factors were a delay to surgery, extensile and posterior surgical approaches to the hip, trochanteric osteotomy, postoperative step-off of >3 mm, and a delay to prophylaxis following injury or surgery. Ethnicity, Injury Severity Score, cause of the fracture, femoral head injuries, degloving injuries, comminution, intra-articular debris, the type of bone void filler, gluteus minimus muscle preservation, prolonged operative time, and intraoperative patient position were not risk factors for developing HO.

CONCLUSIONS

HO following operative fixation of acetabular fractures is not uncommon, with severe-grade HO associated with substantial disability. Careful consideration of the risk factor effect sizes and interdependencies could aid physicians in identifying patients at risk for developing HO and guide their prophylactic management. The results of this study could establish a framework for future studies.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

HETEROTOPIC OSSIFICATION IN ACETABULAR FRACTURES: SYSTEMATIC REVIEW AND META-ANALYSIS OF PROPHYLAXIS

Objective:

Heterotopic ossification is defined as the formation of trabecular bone in soft tissues. It is a common complication after surgical treatment of acetabular fractures. However, its prophylaxis and treatment are still controversial. The objective of this research is to evaluate the effectiveness of actions to prevent the development of heterotopic ossification after surgical correction of acetabular fractures.

Methods:

A systematic review was carried out with research in the databases PubMed/MEDLINE, Embase, LILACS and Cochrane until August 4, 2020, without restrictions on language and year of publication. Only randomized clinical studies carried out in humans without restrictions based on the dosage of treatments, use and duration of prophylaxis were included in this review.

Results:

Two studies compared the use of radiotherapy and indomethacin and three compared the use of indomethacin with a placebo or non-indomethacin group. The meta-analysis calculations did not indicate statistical differences between radiotherapy versus indomethacin (RR 1.45, IC 95% 0.97 to 2.17, p = 0,55) and indomethacin versus placebo or not indomethacin (RR 0.85, IC 95% 0.68 to 1.06, p = 0,59). Conclusion: There is insufficient evidence to affirm that the use of radiotherapy or indomethacin are effective to prevent the formation of heterotopic ossification after surgery for fractures of the acetabulum. In addition, the number of complications was higher in the indomethacin group when compared to placebo or no intervention. Level of Evidence I, Systematic Review.

A Retrospective Analysis of 287 Patients Undergoing Prophylactic Radiation Therapy for the Prevention of Heterotopic Ossification

Purpose

Heterotopic ossification (HO) is a potentially disabling disorder of ectopic bone formation secondary to orthopedic surgery or trauma. In this retrospective analysis we evaluated the outcomes of patients who received radiation therapy (RT) for HO prophylaxis.

Methods and Materials

A total of 287 patients who received RT for HO prophylaxis at a major trauma center from 2007 to 2018 were analyzed. Data collected included types of injury, surgery, time intervals between key events, development of postprophylaxis HO, and secondary malignancies. Associations between various factors and the risk of developing HO were analyzed. Kaplan-Meier analysis was used to estimate failure rates.

Results

The most common indication for RT was traumatic acetabular fracture (83.3%). Twelve patients (4.2%) developed postprophylaxis HO with a median time to failure of 8.6 months (2.8-24.5). Kaplan-Meier 1-, 2-, and 5-year failure rates were 3.7%, 4.4%, and 7.4%, respectively. Injury type and timing of RT were not associated with the risk of failure, but we observed a trend of increased risk of failure in patients with longer time between surgery and RT (odd ration [OR] 1.68, P = .056). Current or former smokers (51.7%) were less likely to fail (OR 0.10, P = .03). There was no incidence of in-field secondary malignancy.

Conclusions

There was no significant association between injury and fracture type, surgical approach, or timing of RT and development of HO, contrary to published reports of increased HO risk with certain surgical approaches and longer time intervals between injury and surgery, suggesting that prophylactic RT might play a role in mitigating these effects. Decreased risk of postprophylaxis HO among former or current smokers was unexpected. No secondary malignancy in the RT field was identified, although the median follow-up was only 17 months. Compared with published HO incidences (17%-39%) in patients who receive no prophylaxis after traumatic acetabular fractures, our results are highly suggestive of the efficacy of prophylactic RT.

Do Indomethacin or Radiation for Heterotopic Ossification Prophylaxis Increase the Rates of Infection or Wound Complications After Acetabular Fracture Surgery?

OBJECTIVES

To compare the rates of infection and wound complications in patients undergoing operative fixation (ORIF) of acetabular fractures receiving heterotopic ossification (HO) prophylaxis using indomethacin or external beam radiation therapy (XRT) versus no prophylaxis.

DESIGN

Retrospective cohort.

SETTING

Level I trauma center.

PATIENTS

We reviewed 473 patients undergoing ORIF of acetabular fractures through posterior, combined, or extensile surgical approaches from 2012 to 2017, with a median follow-up of 13 months (0.5-77 months).

MAIN OUTCOME MEASUREMENT

Rates of infection and wound complications were stratified according to their HO prophylaxis method into three groups as indomethacin, XRT, and no prophylaxis.

RESULTS

Overall, 167 patients (35.3%) received indomethacin, 104 patients (22.0%) received postoperative XRT, and 202 patients (42.7%) received no prophylactic treatment. There was no difference between the 3 groups for the risk of surgical site infection (P = 0.280). The XRT group had a significantly increased risk of noninfectious wound complications (20.2%) compared with the indomethacin group (6.6%, P = 0.002) and the no prophylaxis group (5.0%, P < 0.0001). Multivariate analysis revealed XRT remained a significant risk factor for noninfectious wound complications compared with no prophylaxis (odds ratio 5.39; 95% confidence interval 2.37-12.22; P < 0.0001).

CONCLUSIONS

Although there is no difference between XRT, indomethacin, and no HO prophylaxis for the risk of surgical site infection, the use of XRT results in more than 5 times increased risk of noninfectious wound complications compared with no prophylaxis. This increased risk should be considered when contemplating XRT for HO prophylaxis in acetabular fracture patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Incidence and risk factors for heterotopic ossification following periprosthetic joint infection of the hip

INTRODUCTION

Heterotopic ossifications (HOs) commonly occur following total hip arthroplasty. Data regarding the appearance of HO after periprosthetic joint infection (PJI) of the hip are rare. Therefore, the aim of this study was to analyze the incidence and potential risk factors for the development of HO in patients with PJI of the hip.

MATERIALS AND METHODS

We performed a single-center, retrospective study including patients treated with a two- or multistage operation and patients undergoing salvage procedure in cases of PJI of the hip with a minimum follow-up of 6 months. A total of 150 patients were included in the analysis. The Brooker-scale was used to classify HO. Patients were divided in three groups: (1) No HO, (2) HO Brooker type 1-4, and (3) high-grade HO (HO Brooker type 3 and 4). In each group, we checked possible risk factors for the development of HO for statistical significance.

RESULTS

Patients included in our study had a mean age of 70.4 ± 12.1 years. Of all patients, 75 were women (50%). HOs could be found in 70 patients (46.7%). Twenty-seven patients showed HO Brooker type 1, 23 type 2, 15 type 3 and 5 type 4. Male gender [odds ratio (OR) 2.14; p = 0.022], smoking (OR 5.75; p = 0.025) were significant risk factors for HO. A chronic infection (OR 3.54; p = 0.029) and a higher number of procedures (p = 0.009) were significant risk factors for the development of high-grade HO.

CONCLUSIONS

HOs often occur following surgical care of PJI. Male gender, smoking, a chronic infection and high number of operations are risk factors for developing HO after PJI.

The traumatic bone: trauma-induced heterotopic ossification

Heterotopic ossification (HO) is a common occurrence after multiple forms of extensive trauma. These include arthroplasties, traumatic brain and spinal cord injuries, extensive burns in the civilian setting, and combat-related extremity injuries in the battlefield. Irrespective of the form of trauma, heterotopic bone is typically endochondral in structure and is laid down via a cartilaginous matrix. Once formed, the heterotopic bone typically needs to be excised surgically, which may result in wound healing complications, in addition to a risk of recurrence. Refinements of existing diagnostic modalities, like micro- and nano-CT are being adapted toward early intervention. Trauma-induced HO is a consequence of aberrant wound healing, systemic and local immune system activation, infections, extensive vascularization, and innervation. This intricate molecular crosstalk culminates in activation of stem cells that initiate heterotopic endochondral ossification. Development of animal models recapitulating the unique traumatic injuries has greatly facilitated the mechanistic understanding of trauma-induced HO. These same models also serve as powerful tools to test the efficacy of small molecules which specifically target the molecular pathways underlying ectopic ossification. This review summarizes the recent advances in the molecular understanding, diagnostic and treatment modalities in the field of trauma-induced HO.

Heterotopic Ossification in Acetabular Fracture Surgery

Heterotopic ossification (HO) is a common complication of the surgical treatment of acetabular fractures. HO is the formation of trabecular bone in soft tissues where bone does not usually occur. Over the last decade, many risk factors have been identified for HO after surgical fixation of acetabular fractures; however, prophylaxis and treatment of this condition are controversial. Potential preventive measures range from NSAIDs to external beam irradiation, but recent studies have questioned the utility of these measures. The Brooker classification system, which has been correlated with patient function and outcomes, is most commonly used to describe HO severity. Advances will assist in the diagnosis, prevention, and management of HO as well as the assessment of risk factors that could affect outcomes.

Heterotopic Ossification in Trauma

Better understanding of the biology of heterotopic ossification (HO) formation will lead to treatment and prevention modalities that can be directed specifically at the cellular level. Early identification of HO precursor cells and target genes may provide prognostic value that guides individualized prophylactic treatment. Better understanding of molecular signaling and proteomics variability will allow surgeons to individualize preemptive treatment to suppress inflammation and formation of HO. Careful surgical technique to avoid muscle damage is important. Damaged muscle should be debrided as a prophylactic measure. Hemostasis and avoidance of a postoperative hematoma may decrease the chance of formation of HO.

Radiotherapy for benign disease; assessing the risk of radiation-induced cancer following exposure to intermediate dose radiation

Most radiotherapy (RT) involves the use of high doses (>50 Gy) to treat malignant disease. However, low to intermediate doses (approximately 3-50 Gy) can provide effective control of a number of benign conditions, ranging from inflammatory/proliferative disorders (e.g. Dupuytren's disease, heterotopic ossification, keloid scarring, pigmented villonodular synovitis) to benign tumours (e.g. glomus tumours or juvenile nasopharyngeal angiofibromas). Current use in UK RT departments is very variable. This review identifies those benign diseases for which RT provides good control of symptoms with, for the most part, minimal side effects. However, exposure to radiation has the potential to cause a radiation-induced cancer (RIC) many years after treatment. The evidence for the magnitude of this risk comes from many disparate sources and is constrained by the small number of long-term studies in relevant clinical cohorts. This review considers the types of evidence available, i.e. theoretical models, phantom studies, epidemiological studies, long-term follow-up of cancer patients and those treated for benign disease, although many of the latter data pertain to treatments that are no longer used. Informative studies are summarized and considered in relation to the potential for development of a RIC in a range of key tissues (skin, brain etc.). Overall, the evidence suggests that the risks of cancer following RT for benign disease for currently advised protocols are small, especially in older patients. However, the balance of risk vs benefit needs to be considered in younger adults and especially if RT is being considered in adolescents or children.