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

Preventing complications during acetabular fracture surgery, a review

Complications after acetabular fracture surgery include: hemorrhage, nerve injury, infection, malreduction, heterotopic ossification, post-traumatic arthritis, and medical complications may reach an incidence of 30-50 %. Total hip arthroplasty can salvage a poor reduction or post-traumatic arthritis but has higher complication rates then a primary replacement and in many cases may have to last 50 years. Sciatic nerve palsy, which is often caused by the injury, and infection/osteomyelitis, which is often caused by the surgical intervention, result in universally poor outcomes and every effort should be aimed at avoiding these. Methods of avoiding complications and treatment once they occur are discussed.

Standardized protocol during acetabular fracture surgery results in low rates of heterotopic ossification

PURPOSE

To assess the rate of heterotopic ossification (HO) following acetabular surgery with a standardized protocol via the Kocher-Langenbeck. Secondarily, to evaluate patient characteristics, injury variables, and perioperative data among patients with HO and no HO.

METHODS

This was a retrospective case series from an academic Level I trauma center. Included patients had displaced acetabular fractures treated via Kocher-Langenbeck approach with debridement of (1) gluteus minimus muscle (GMM) from the posterior wall and column up to the superior gluteal neurovascular bundle, (2) unhealthy appearing piriformis muscle without fascial disruption, and (3) superior and inferior gemelli in the location of implant placement. Those with posterior hip dislocations and gluteus medius injury received prophylactic indomethacin.

RESULTS

Fifty-seven patients met inclusion criteria. Thirteen patients (22.8%) developed HO, and 44 patients (77.2%) had no evidence of HO. Ten (17%) patients developed mild HO (Brooker classification (BC) I/II), 3 (5%) developed moderate HO (BC III), and no patients developed severe HO (BC IV). There were no differences in the prevalence of elementary versus associated acetabular fracture patterns or individual fracture patterns among cohorts. Patients with HO had longer times to surgical intervention (5.3 ± 5.1 days vs. 2.4 ± 1.6 days, p = 0.002) and length of intensive care unit (ICU) stay (6.7 ± 12.2 days vs. 1.5 ± 3.3 days, p = 0.013) compared with the no HO cohort. There was no difference in rates of HO prophylaxis use and subsequent HO among cohorts.

CONCLUSION

This study describes a standardized protocol developed by the senior author that resulted in low rates of HO following acetabular fixation via the Kocher-Langenbeck approach. Patients with HO had a significantly longer time to surgical intervention and length of ICU level of care.

LEVEL OF EVIDENCE

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

Radiation Therapy for Heterotopic Ossification: A Systematic Review

PURPOSE

Heterotopic ossification (HO) is a benign disorder characterized by ectopic bone formation in soft tissues that can lead to functional loss in patients. We conducted a systematic review of the evidence on the use of radiation therapy (RT) for the prevention or treatment of HO.

METHODS AND MATERIALS

Literature searches were conducted using Medline (via PubMed), Embase, and ClinicalTrials.gov until April 1, 2023. Medical subject headings and free text terms relevant to HO and RT were used. In brief, eligible study participants were ≥18 years of age with HO and were treated with low-dose external RT. Two reviewers screened relevant abstracts and extracted full-text data for analysis. The review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines.

RESULTS

Ten studies evaluating the effect of RT for either the prevention or treatment of HO met the inclusion for evidence synthesis. Nine randomized controlled trials did not clearly report their methods and had a medium risk of bias. The studies were conducted between 1988 and 2008, with follow-up ranging on average from 3 to 59 months posttreatment. A total of 1530 participants were analyzed, and 566 were treated with RT following fracture fixation, total hip arthroplasty, or total hip replacement. In pooled data from 8 randomized controlled trials, there was a nonsignificant but clinically meaningful reduction in the presence of HO at follow-up for patients who received RT versus comparators (pooled odds ratio, 0.47; 95% CI, 0.19, 1.17). There was minimal evidence of adverse events.

CONCLUSIONS

This systematic review found a clinically, but not statistically, significant benefit of prophylactic RT for HO at follow-up. These findings are tempered by a moderate risk of bias. While practice patterns vary, RT for HO prophylaxis in high-risk patients may have benefits that outweigh the risks.

Physical and psychosocial outcomes among burn-injured people with heterotopic ossification: A burn model system study

INTRODUCTION

Heterotopic ossification (HO), or ectopic bone formation in soft tissue, is a not so rare and poorly understood debilitating sequela of burn injury. Individuals developing HO following burn injuries to their hands often experience reductions in mobility, significant contractures, and joint pain. This study identifies demographic characteristics of individuals who develop HO and compares their physical and psychosocial outcomes to the general burn population.

METHODS

Participant demographics, injury characteristics, and PROMIS-29 scores across three time points (discharge, six- and 12- months after injury) were extracted from the Burn Model System National Longitudinal Database representing participants from 2015-2022. Mixed-effects linear regression models were used to compare PROMIS scores across all three longitudinal measurements. Models were adjusted for age, sex, race/ethnicity, HO status, and burn size.

RESULTS

Of the 861 participants with data concerning HO, 33 were diagnosed with HO (3.8% of participants). Most participants with HO were male (n = 24, 73%) and had an average age of 40 + /- 13 years. Participants with HO had significantly larger burn size (49 +/-23% Total Body Surface Area (TBSA)) than those without HO (16 +/-17%). Participants with HO reported significantly worse physical function, depression, pain interference and social integration scores than those without HO. After adjusting for covariables, participants with HO continued to report statistically significantly worse physical function than those without HO. Although physical functioning was consistently lower, the two populations did not differ significantly among psychosocial outcome measures.

CONCLUSIONS

While HO can result in physical limitations, the translation to psychosocial impairments was not evident. Targeted treatment of HO with the goal of maximizing physical function should be a focus of their rehabilitation.

LEVEL OF EVIDENCE

2b TYPE OF STUDY: Symptom Prevalence Study.

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.

Hydroxyapatite/hyperbranched polyitaconic acid/chitosan composite scaffold for bone tissue engineering

In this study, a promising modified composite scaffold (hydroxyapatite/hyperbranched polyitaconic acid/chitosan) was synthesized for bone tissue engineering. Novel hyperbranched polyitaconic acid was prepared through the polymerization of itaconic acid using reversible addition fragmentation chain transfer using a macro‐RAFT agent. The chemical structure of the prepared hyperbranched polyitaconic acid was characterized by FTIR and 1HNMR and was subsequently embedded into hydroxyapatite/chitosan composite. The obtained modified composite scaffold was evaluated by characterizing its porosity, mechanical properties, bioactivity and cytotoxicity. The results showed that the modified composite scaffold had higher mechanical strength (i.e., 0.56 ± 0.03 MPa) in comparison to chitosan/hydroxyapatite scaffold only (i.e., 0.31 ± 0.01 MPa) and also showed higher bioactivity. In addition, the modified composite scaffold (HAP/HBP‐RAFT‐PI/CS) showed anticancer properties and enhanced human skin fibroblasts proliferation.