Osteosarcoma following single fraction radiation prophylaxis for heterotopic ossification

Efficacy of ibuprofen and indomethacin as prophylaxis of heterotopic ossification: a comparative study

The prophylactic action of non-steroidal anti-inflammatory drugs (NSAIDs) in heterotopic ossification (HO) was first described following analgesic therapy with indomethacin. Following that evidence, several compounds have been successfully used for prophylaxes of HO. Ibuprofen has been also proposed for the prevention of HO following THA. The present study compared the administration of ibuprofen for three weeks versus indomethacin as prophylaxis for HO following primary THA. In all THA procedures, pre- and post-operative protocols were conducted in a highly standardized fashion. The type of HO prophylaxis (indomethacin 100 mg/daily or ibuprofen 100 mg/daily) was chosen according to a chronological criterion: from 2017 to 2019 indomethacin was used, whereas from 2019 to 2022 ibuprofen was administered. In case of allergy or intolerance to NSAIDs, no prophylaxis was performed, and patients were included as a control group. All patients who underwent an anteroposterior radiography of the pelvis at a minimum of 12 months following THA were considered for inclusion. On admission, the age and sex of the patients were recorded. Moreover, the causes of osteoarthritis and the date of surgery were recorded. The grade of HO was assigned by a blinded assessor who was not involved in the clinical management of the patients. The modified Brooker Staging System was used to rate the efficacy of the interventions. Data from 1248 patients were collected. 62% (767 of 1248 patients) were women. The mean age was 67.0 ± 2.9 years. The mean follow-up was 21.1 ± 10.8 months. In the ibuprofen group, 73% of patients evidenced Brooker 0, 17% Brooker I, and 10% Brooker II. In the indomethacin group, 77% of patients evidenced Brooker 0, 16% Brooker I, 6% Brooker II. No patient in the ibuprofen and indomethacin group developed Brooker III or IV. In the control group, 64% of patients evidenced Brooker 0, 21% Brooker I, 3% Brooker II, and 12% Brooker III. No patient in the control group developed Brooker IV HO. Concluding, three weeks of administration of ibuprofen demonstrated similar efficacy to indomethacin in preventing HO following primary THA. The prophylaxis with ibuprofen or indomethacin was more effective in preventing HO compared to a control group who did not receive any pharmacological prophylaxis.

A microCT-based platform to quantify drug targeting

BACKGROUND

Heterotopic ossification (HO) is a frequent and debilitating complication of traumatic musculoskeletal injuries and orthopedic procedures. Prophylactic dosing of botulinum toxin type A (BTxA) holds potential as a novel treatment option if accurately distributed throughout soft-tissue volumes where protection is clinically desired. We developed a high-resolution, microcomputed tomography (microCT)-based imaging strategy to assess drug distribution and validated this platform by quantifying distribution achieved via a prototype delivery system versus a single-bolus injection.

METHODS

We injected an iodine-containing contrast agent (iodixanol 320 mg I/mL) into dissected rabbit musculature followed by microCT imaging and analysis. To contrast the performance of distributed versus bolus injections, a three-dimensional (3D) 64-cm3-printed soft-tissue holder was developed. A centered 2-cm3 volume of interest (VOI) was targeted with a single-bolus injection or an equal volume distributed injection delivered via a 3D-printed prototype. VOI drug coverage was quantified as a percentage of the VOI volume that was < 1.0 mm from the injected fluid.

RESULTS

The microCT-based approach enabled high-resolution quantification of injection distribution within soft tissue. The distributed dosing prototype provided significantly greater tissue coverage of the targeted VOI (72 ± 3%, mean ± standard deviation) when compared to an equal volume bolus dose (43 ± 5%, p = 0.031) while also enhancing the precision of injection targeting.

CONCLUSIONS

A microCT-based imaging technique precisely quantifies drug distribution within a soft-tissue VOI, providing a path to overcome a barrier for clinical translation of prophylactic inhibition of HO by BTxA.

RELEVANCE STATEMENT

This platform will facilitate rapid optimization of injection parameters for clinical devices used to effectively and safely inhibit the formation of heterotopic ossification.

KEY POINTS

• MicroCT provides high-resolution quantification of soft-tissue drug distribution. • Distributed dosing is required to maximize soft-tissue drug coverage. • Imaging platform will enable rapid screening of 3D-printed drug distribution prototypes.

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 role of miRNA and lncRNA in heterotopic ossification pathogenesis

Heterotopic ossification (HO) is the formation of bone in non-osseous tissues, such as skeletal muscles. The HO could have a genetic or a non-genetic (acquired) background, that is, it could be caused by musculoskeletal trauma, such as burns, fractures, joint arthroplasty (traumatic HO), or cerebral or spinal insult (neurogenetic HO). HO formation is caused by the differentiation of stem or progenitor cells induced by local or systemic imbalances. The main factors described so far in HO induction are TGFβ1, BMPs, activin A, oncostatin M, substance P, neurotrophin-3, and WNT. In addition, dysregulation of noncoding RNAs, such as microRNA or long noncoding RNA, homeostasis may play an important role in the development of HO. For example, decreased expression of miRNA-630, which is responsible for the endothelial-mesenchymal transition, was observed in HO patients. The reduced level of miRNA-421 in patients with humeral fracture was shown to be associated with overexpression of BMP2 and a higher rate of HO occurrence. Down-regulation of miRNA-203 increased the expression of runt-related transcription factor 2 (RUNX2), a crucial regulator of osteoblast differentiation. Thus, understanding the various functions of noncoding RNAs can reveal potential targets for the prevention or treatment of HO.

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.

Primary Versus Secondary Radiotherapy for Heterotopic Ossification Prevention About the Elbow

OBJECTIVES

To examine the efficacy and safety of radiotherapy for the prevention of heterotopic ossification (HO) about the elbow.

DESIGN

Retrospective chart review.

SETTING

Level 1 trauma center.

PATIENTS/PARTICIPANTS

Two hundred and twenty-nine patients who received prophylactic radiotherapy (XRT) over a 15-year period were identified. Patients were included if they received XRT to the elbow joint and had at least 12 weeks of follow-up after XRT. Fifty-four patients were ultimately included.

INTERVENTION

All patients were treated with a single dose of 7 Gy. Ninety-eight percentage of patients received XRT within 24 hours after surgery, and all patients received XRT within 72 hours after surgery.

MAIN OUTCOMES MEASUREMENTS

The primary study measures evaluated were the presence or absence of clinically symptomatic HO and the presence of radiographic HO after XRT to the elbow joint.

RESULTS

Eighteen patients were treated with XRT after a traumatic injury requiring surgery (primary prophylaxis), and 36 were treated with XRT after excision surgery to remove HO which had already formed (secondary prophylaxis). In the primary cohort, 16.7% developed symptomatic HO after XRT and 11.1% required surgery to resect the heterotopic bone. In the secondary cohort, 11.1% developed symptomatic HO after surgery and XRT and 5.5% required resection surgery. No secondary malignancies were identified.

CONCLUSIONS

Our findings suggest that XRT for elbow HO may be safe and effective for both primary and secondary HO. XRT for HO was not shown to be associated with radiation-induced sarcoma in this series, at least in the short term. Further study in a large patient population with extended follow-up is required to better characterize populations at high risk for development of HO and secondary malignancy.

LEVEL OF EVIDENCE

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

Surgical Treatment of a Symptomatic Diaphyseal Tibiofibular Synostosis in a Professional Rugby Player: A Case Report and Literature Review

CONTEXT

Diaphyseal tibiofibular synostosis (DTS) is a rare pathology with unknown origin especially occurring in intensive sport athletes. No therapeutic guideline has been well established in the literature.

CASE PRESENTATION

A rare case of DTS in a 26-year-old professional rugby player has been described. A 5-month exhaustive conservative treatment including physiotherapy and oral medication has been achieved but failed. Management and Outcomes: Following the conservative treatment failure, the DTS has been widely removed including the adjacent interosseous membrane, and the patient could return to competition at the same level after 5 months of convalescence. No recurrence has been revealed at a 35-month follow-up at least.

CONCLUSION

In accordance with the literature data and even if the pathophysiology remains obscure, resection of DTS seems to be the adapted treatment to allow and to reduce professional athletes' recovery time at the same sport level. The resection including a part of the tibiofibular interosseous membrane could avoid the occurrence of recurrence. Conservative treatment should be reserved for senior patients with a low sport activity.

Synostosis of the interphalangeal joint: an uncommon cause of post-fracture digital stiffness

Loss of motion and stiffness after fracture of the digits are most commonly a result of soft tissue contracture and adhesions. However, stiffness can also have a bony etiology. We present a case of synostosis of the thumb interphalangeal joint after non-operative treatment of a closed fracture.

NSAIDs for Prophylaxis for Heterotopic Ossification After Total Hip Arthroplasty: A Bayesian Network Meta-analysis

Non-steroidal anti-inflammatory drugs (NSAID) have been recommended to prevent of heterotopic ossification (HO) after total hip arthroplasty (THA), but debates are still ongoing. The present Bayesian network meta-analysis of randomized clinical trials (RCTs) compared all available pathways of NSAID treatment as prophylaxis for HO after THA. The present Bayesian network meta-analysis was conducted according to The PRISMA Extension Statement for Reporting of Systematic Reviews Incorporating Network Meta-analyses of Health Care Interventions guidelines. All randomized clinical trials comparing two or more interventions to prevent HO after THA were considered for analysis. HO was classified according to Brooker. The quality of the methodological assessment was performed through the risk of bias summary tool of the Review Manager Software 5.3 (The Cochrane Collaboration, Copenhagen). The network meta-analysis was performed through a STATA routine for Bayesian hierarchical random-effects model analysis, with log odd ratio (LOR) effect measure. Data from 26 studies (6396 THAs; 58% females) were collected. The mean follow-up was 10.50 ± 5.7 months. ANOVA showed good comparability among mean age and gender (P > 0.5). Celecoxib demonstrated the highest rate of Brooker class 0 (LOR 6.96), followed by diclofenac (LOR 6.94). Naproxen demonstrated the lowest rate of Brooker I HO (LOR 2.82), followed by celecoxib (LOR 3.52). Celecoxib demonstrated lowest rate of Brooker class II HO (LOR 1.66), class III (LOR), and class IV (LOR 0.25). The equation for global linearity detected no statistically significant inconsistency (P > 0.5) in all the comparisons. The present Bayesian network meta-analysis encourages the use of celecoxib as a prophylaxis for HO. These conclusions must be interpreted in light of the limitations of the present study. Future investigations are required to establish more definitely the role of celecoxib.Level of Evidence: I, Bayesian network analysis of RCTs.

Neurological heterotopic ossification: novel mechanisms, prognostic biomarkers and prophylactic therapies

Neurological heterotopic ossification (NHO) is a debilitating condition where bone forms in soft tissue, such as muscle surrounding the hip and knee, following an injury to the brain or spinal cord. This abnormal formation of bone can result in nerve impingement, pain, contractures and impaired movement. Patients are often diagnosed with NHO after the bone tissue has completely mineralised, leaving invasive surgical resection the only remaining treatment option. Surgical resection of NHO creates potential for added complications, particularly in patients with concomitant injury to the central nervous system (CNS). Although recent work has begun to shed light on the physiological mechanisms involved in NHO, there remains a significant knowledge gap related to the prognostic biomarkers and prophylactic treatments which are necessary to prevent NHO and optimise patient outcomes. This article reviews the current understanding pertaining to NHO epidemiology, pathobiology, biomarkers and treatment options. In particular, we focus on how concomitant CNS injury may drive ectopic bone formation and discuss considerations for treating polytrauma patients with NHO. We conclude that understanding of the pathogenesis of NHO is rapidly advancing, and as such, there is the strong potential for future research to unearth methods capable of identifying patients likely to develop NHO, and targeted treatments to prevent its manifestation.

Radiation therapy for the prevention of heterotopic ossification: Efficacy and toxicity of single fraction radiotherapy

Numerous nonmalignant diseases can be treated with radiation therapy (RT). Among them, Heterotopic Ossification (HO) is a benign condition resulting from several causes that can be successfully managed with ionizing radiation. More often seen in the hip area after major surgical procedures, HO is of major concern as it can lead to functional disorders, pain and even to joint ankylosis. We retrospectively analyzed the outcome of therapeutic irradiation for the prevention of HO in 14 patients treated in our hospital between 2005 and 2011. All patients were irradiated with a dose ranging from 7 to10 Gy in a single fraction for prevention of HO after surgery. After a median follow up of 126 months (range 96 – 156 months) none of our patients developed HO. Impaired wound healing or other post surgery complications like trochanteric nonunion were not observed. A single fraction of RT seems to be a sufficient, cost effective and safe treatment regimen. In our study we report excellent results as none of our patients developed HO.

Radiation-Induced Sarcoma After Heterotopic Ossification Prophylaxis: A Case Report

CASE

Heterotopic ossification (HO) is a pathological formation of bone in nonosseous tissue and is a common complication of orthopaedic procedures. Radiotherapy is often used to prevent HO despite the small risk of secondary malignancy. Here, we report a case of a patient who developed a periprosthetic, radiation-induced sarcoma after delivery of a single fraction of 7 Gy for HO prophylaxis. This sarcoma was found to lie entirely within the treatment field and occurred within 5 years of radiation.

CONCLUSION

Appropriate counseling regarding radiation-induced sarcoma formation should be provided to patients considering radiotherapy for this HO prophylaxis.

[The role of interleukin-11 in osteosarcoma]

Osteosarcoma is an often highly malignant mesenchymal tumor. By definition, osteosarcoma cells are able to form osteoid, which can mature into tumor bone. Osteosarcoma metastasizes preferentially to the lung. In Europe, the incidence is between 2 and 5 new diagnoses per 1,000,000 people per year. The underlying mechanisms for osteosarcoma formation are not well understood. However, previous radiotherapy or exposition to nuclear radiation increase the risk of osteosarcoma. Patients are usually treated with a neoadjuvant chemotherapy, followed by complete surgical resection of the tumor and post-surgical chemotherapy, which leads to a five-year survival rate of approximately 70% for all stages. Scientific publications in recent years have shown that expression of the cell surface protein interleukin-11 receptor (IL-11R) correlates with a worse prognosis for patients. The IL-11R is activated by its ligand, the cytokine IL-11. IL-11 activates several intracellular signaling cascades within its target cells and is known to be an important regulator of bone homeostasis. Patients with dysfunctional IL-11 signaling display different forms of craniosynostosis. IL-11 induces proliferation of osteosarcoma cell lines in vitro, and the IL-11 signaling cascade was further used to reduce tumor growth and lung metastasis in preclinical mouse models of primary intratibial osteosarcoma. This article gives a comprehensive overview of the frequency, classification, and etiology of osteosarcoma and describes the basic biology of the cytokine IL-11. Furthermore, it summarizes current knowledge about the functional role of IL-11 in osteosarcoma and lists possible therapeutic opportunities.

Heterotopic Ossification of the Inferior Pubic Ramus

The hip is a common location for heterotopic ossification after surgical trauma, blunt trauma, or muscle injury. However, the region around the pubic rami is an unusual location for heterotopic bone formation. Here, we present a case of a young, active man in the Armed Forces Reserve with a large heterotopic bone involving the left inferior pubic ramus who underwent surgical excision through an unusual approach via the perineum. The patient had notable pain relief postoperatively and returned to his active duties 1 month after surgery without discomfort or functional limitation.

Heterotopic Ossification Formation Following a Simple Concussion: A Case Report

CASE

A 19-year-old woman presented with a 3-month history of an enlarging lesion on the proximal aspect of the femur. After imaging studies and a biopsy had been performed, the mass was determined to represent heterotopic ossification (HO). The only known risk factor was a history of concussion. The mass was resected and, as of the 12-month follow-up, had not recurred.

CONCLUSION

HO is a potentially serious complication of ossification in soft tissues that can develop secondary to several disease states; it commonly occurs following traumatic brain injury. To our knowledge, this is the only case report that describes HO associated with a concussion and no other risk factors.

Heterotopic ossifications: role of radiotherapy as prophylactic treatment

BACKGROUND

Heterotopic ossification (HO) is abnormal formation of lamellar bone in soft tissue; the most frequent causes are total hip arthroplasty and trauma. Severe cases can lead to ankilosis with important impact on quality of life. Surgery is the elective treatment, but, especially in high-risk patients, it is important to prevent the re-formation of HO and, in these cases, radiotherapy (RT) can play an important role.

MATERIALS AND METHODS

we retrospectively analyzed a mono-institutional casistic of 30 patients (31 sites) at high risk for HO development, treated with surgery and pre- or postoperative RT. The majority of patients received a single RT fraction of 7 Gy, median age was 62, with a prevalence of male and hip as most frequently involved site. Radiological studies and clinical examination were performed in all patients during the follow-up period to evaluate both treatment efficacy and acute or late toxicity.

RESULTS

With a median follow up of 67 months, 23 patients had a complete response (CR) with excellent results in term of joint mobility. Two patients with CR showed a relapse of HO in the same site 19 and 12 months after treatment, respectively. Seven patients (22,6%) had a partial response (PR) to RT. One patient who reached CR had a history of previous irradiation in the same site 16 years before. No acute or late reactions have been reported.

CONCLUSION

Our data confirm safety and efficacy of RT in preventing HO, especially in high-risk patients, preferring a single fraction of 7 Gy.

Testicular Dose During Prophylaxis of Heterotopic Ossification with Radiation Therapy

AIM

A single-institution, retrospective study was performed to investigate potential techniques to minimize radiation exposure to the testicles during heterotopic ossification (HO) prophylaxis. We report the impact of split-beam technique (SBT) and different photon energies on the total dose of radiation received by the testicles during prophylaxis of HO.

MATERIALS AND METHODS

Between 2008 and 2010, we identified 64 patients with traumatic acetabular fractures who underwent surgery followed by radiation therapy (RT) without testicular shielding. Postoperative RT was delivered within 72 h in a single fraction of 700 cGy using 6-18 MV photons, without testicular shielding due to patient refusal. All patients underwent 3-D RT planning in which the testicles were contoured as a region of interest and dose-volume histograms (DVH) were generated. Additional treatment planning trials were created for each patient by utilizing a SBT medially and by using different photon energies (6, 10 and 18 MV) to study the effects of these maneuvers on the delivered dose to the testicles.

RESULTS

In reviewing the DVH, it was noted that the mean dose delivered to the testicles was 10 cGy (range=3-40). The maximum dose was 31 cGy (range=7-430). When SBT was utilized, a significant reduction in the mean (44%) and maximum (47%) doses delivered to the testicles was noted. Further reductions in the mean (26%) and maximum (14%) doses were achieved by using higher-energy (10-18 MV) beams. The radiation doses to the testicles from the CT simulation and the two portal images were estimated to be 4 and 1.5 cGy, respectively.

CONCLUSION

Low-dose prophylactic RT to prevent HO around the hip causes a low, but likely biologically meaningful, radiation dose to be delivered to the testicles. This dose could be further reduced by using a medial SBT and photon energies above 6 MV. Testicular shielding should be offered to all male patients receiving such RT. In addition, all patients should be informed about the consequences of testicular radiation as part of their informed consent.

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.

The clinical implications of heterotopic ossification in patients treated with radial head replacement for trauma: A case series and review of the literature

Radial head arthroplasty (RHA) is an acceptable treatment for comminuted radial head fractures (RHF). Fourteen patients with no postop HO prophylaxis were treated with RHA for comminuted RHF. A 50% incidence in HO was seen following RHA with a statistically increased risk (p ≤ 0.05) of reoperation compared to those without HO. Decreased ROM was seen on the affected side (p ≤ 0.05); patients without HO showed no statistical difference (p ≥ 0.05) in ROM or grip strength. HO following RHA increases patient risk for reoperation and decreases ROM. We recommend HO prophylaxis with NSAIDs and/or radiotherapy if no direct patient contraindications are found.

Does Postoperative Radiation Decrease Heterotopic Ossification After the Kocher-Langenbeck Approach for Acetabular Fracture?

BACKGROUND

Controversy regarding heterotopic ossification (HO) prophylaxis exists after Kocher-Langenbeck for treatment of acetabular fracture. Prophylaxis options include antiinflammatory oral medications, single-dose radiation therapy, and débridement of gluteus minimus muscle. Prior literature has suggested single-dose radiation therapy as the best prophylaxis to prevent HO formation. However, recent reports have emerged of radiation-induced sarcoma after radiotherapy for HO prophylaxis, which has led many surgeons to reconsider the risks and benefits of single-dose radiation therapy. We set out to determine if radiotherapy, in addition to standard débridement of gluteus minimus muscle, affected postoperative HO formation after a Kocher-Langenbeck approach for acetabular fracture.

QUESTIONS/PURPOSES

(1) After the Kocher-Langenbeck approach and gluteus minimus débridement, is single-dose radiotherapy associated with a decreased risk of HO? (2) Does addition of single-dose radiotherapy prolong length of stay after a Kocher-Langenbeck approach and gluteus minimus débridement as compared with patients without radiotherapy?

METHODS

After institutional review board approval, all adult patients treated for acetabular fracture by a single surgeon with a Kocher-Langenbeck approach between August 2011 and October 2014 were identified (n = 60). Débridement of gluteus minimus muscle caudal to the superior gluteal bundle was standard in all patients. Radiotherapy was given with a single dose of 700 cGy within 72 hours of surgery from August 2011 until April 2013. Patients treated subsequently did not receive radiotherapy. Patients treated with indomethacin (n = 1) and with fewer than 10 weeks followup were excluded (n = 12) because several studies suggest that most HO that develops is visible by that point in time. Our study group totaled 46 patients with 24 in the radiotherapy and débridement group and 22 in the débridement group. Charts were reviewed to determine length of stay. Attending orthopaedic trauma surgeons who were blinded to the patient's treatment group graded all followup radiographs according to the Brooker system, and Classes III and IV HO were considered clinically important Fisher's exact test was used to analyze clinically significant differences HO between the two groups. Length of stay was compared using a t-test.

RESULTS

Single-dose radiotherapy is associated with a decreased risk of clinically important (Brooker III-IV) HO after a Kocher-Langenbeck approach and gluteus minimus débridement (radiotherapy: one of 24 [4%], no radiotherapy: seven of 22 [32%], relative risk: 0.131 [95% confidence interval {CI}, 0.018-0.981], p = 0.020). Addition of single-dose radiotherapy did not result in increased length of stay (radiotherapy: 12 ± 7.0 days; no radiotherapy: 11 ± 7.2 days; mean difference: 1.0 [95% CI, -3.2 to 5.2] days, p = 0.635).

CONCLUSIONS

Single-dose radiation in combination with gluteus minimus débridement decreases the risk of clinically important HO compared with gluteus minimus débridement alone after a Kocher-Langenbeck approach for acetabular fracture. No differences in length of stay were seen. Surgeons who chose not to use radiotherapy as a result of concern for future sarcoma may see higher rates of clinically significant HO after a Kocher-Langenbeck approach for acetabular fracture fixation.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Management algorithm for HIV-associated parotid lymphoepithelial cysts

We report an evidence-based management algorithm for benign lymphoepithelial cysts (BLEC) of the parotid glands in HIV patients based on long-term outcomes after radiation therapy. From 1987 to 2013, 72 HIV-positive patients with BLEC of the parotid glands treated at our institutions were identified and their medical records were reviewed and analyzed. The primary endpoint of our study was to determine a dose response in HIV patients with BLEC. In group A (≤18 Gy), which received a median dose of 10 Gy (8-18), overall response (OvR), complete response (CR), partial response (PR), and local failure (LF) was experienced by 7, 7, 0, and 93 %, respectively. In group B (≥22.5 Gy), which received a median dose of 24 Gy (22.5-30), OvR, CR, PR, and LF was experienced by 88, 65, 23, and 12 %. Logistic regression revealed that higher dose (≥22.5 Gy) predicted for cosmetic control (p = 0.0003). Multiple regression analysis revealed higher dose predicted for cosmetic control (p = 0.0001) after adjusting for confounding variables (age, gender, race, HAART use, BLEC duration, and fractionation size). No patients in either group experienced RTOG grade ≥3 toxicities. A radiation dose of 24 Gy delivered in 12-16 fractions of 1.5-2 Gy per fraction provides long-term cosmetic control in HIV-positive patients with BLEC of the parotid glands.

Cationic Nanogel-mediated Runx2 and Osterix siRNA Delivery Decreases Mineralization in MC3T3 Cells

BACKGROUND

Heterotopic ossification (HO) may occur after musculoskeletal trauma, traumatic brain injury, and total joint arthroplasty. As such, HO is a compelling clinical concern in both military and civilian medicine. A possible etiology of HO involves dysregulated signals in the bone morphogenetic protein osteogenic cascade. Contemporary treatment options for HO (ie, nonsteroidal antiinflammatory drugs and radiation therapy) have adverse effects associated with their use and are not biologically engineered to abrogate the molecular mechanisms that govern osteogenic differentiation.

QUESTIONS/PURPOSES

We hypothesized that (1) nanogel-mediated short interfering RNA (siRNA) delivery against Runt-related transcription factor 2 (Runx2) and osterix (Osx) genes will decrease messenger RNA expression; (2) inhibit activity of the osteogenic marker alkaline phosphatase (ALP); and (3) inhibit hydroxyapatite (HA) deposition in osteoblast cell cultures.

METHODS

Nanogel nanostructured polymers delivered siRNA in 48-hour treatment cycles against master osteogenic regulators, Runx2 and Osx, in murine calvarial preosteoblasts (MC3T3-E1.4) stimulated for osteogenic differentiation by recombinant human bone morphogenetic protein (rhBMP-2). The efficacy of RNA interference (RNAi) therapeutics was determined by quantitation of messenger RNA knockdown (by quantitative reverse transcription-polymerase chain reaction), downstream protein knockdown (determined ALP enzymatic activity assay), and HA deposition (determined by OsteoImage™ assay).

RESULTS

Gene expression assays demonstrated that nanogel-based RNAi treatments at 1:1 and 5:1 nanogel:short interfering RNA weight ratios reduced Runx2 expression by 48.59% ± 19.53% (p < 0.001) and 43.22% ± 18.01% (both p < 0.001). The same 1:1 and 5:1 treatments against both Runx2 and Osx reduced expression of Osx by 51.65% ± 10.85% and 47.65% ± 9.80% (both p < 0.001). Moreover, repeated 48-hour RNAi treatment cycles against Runx2 and Osx rhBMP-2 administration reduced ALP activity after 4 and 7 days. ALP reductions after 4 days in culture by nanogel 5:1 and 10:1 RNAi treatments were 32.4% ± 12.0% and 33.6% ± 13.8% (both p < 0.001). After 7 days in culture, nanogel 1:1 and 5:1 RNAi treatments produced 35.9% ± 14.0% and 47.7% ± 3.2% reductions in ALP activity. Osteoblast mineralization data after 21 days suggested that nanogel 1:1, 5:1, and 10:1 RNAi treatments decreased mineralization (ie, HA deposition) from cultures treated only with rhBMP-2 (p < 0.001). However, despite RNAi attack on Runx2 and Osx, HA deposition levels remained greater than non-rhBMP-2-treated cell cultures.

CONCLUSIONS

Although mRNA and protein knockdown were confirmed as a result of RNAi treatments against Runx2 and Osx, complete elimination of mineralization processes was not achieved. RNAi targeting mid- and late-stage osteoblast differentiation markers such as ALP, osteocalcin, osteopontin, and bone sialoprotein) may produce the desired RNAi-nanogel nanostructured polymer HO prophylaxis.

CLINICAL RELEVANCE

Successful HO prophylaxis should target and silence osteogenic markers critical for heterotopic bone formation processes. The identification of such markers, beyond RUNX2 and OSX, may enhance the effectiveness of RNAi prophylaxes for HO.

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

OBJECTIVE

Radiotherapy (RT) is effective in preventing heterotopic ossification (HO) around acetabular fractures requiring surgical reconstruction. We audited outcomes and estimated risks from RT prophylaxis, and alternatives of indometacin or no prophylaxis.

METHODS

34 patients underwent reconstruction of acetabular fractures through a posterior approach, followed by a 8-Gy single fraction. The mean age was 44 years. The mean time from surgery to RT was 1.1 days. The major RT risk is radiation-induced fatal cancer. The International Commission on Radiological Protection (ICRP) method was used to estimate risk, and compared with a method (Trott and Kemprad) specifically for estimating RT risk for benign disease. These were compared with risks associated with indometacin and no prophylaxis.

RESULTS

28 patients (82%) developed no HO; 6 developed Brooker Class I; and none developed Class II-IV HO. The ICRP method suggests a risk of fatal cancer in the range of 1 in 1000 to 1 in 10,000; the Trott and Kemprad method suggests 1 in 3000. For younger patients, this may rise to 1 in 2000; and for elderly patients, it may fall to 1 in 6000. The risk of death from gastric bleeding or perforation from indometacin is 1 in 180 to 1 in 900 in older patients. Without prophylaxis risk of death from reoperation to remove HO is 1 in 4000 to 1 in 30,000.

CONCLUSION

These results are encouraging, consistent with much larger series and endorse our multidisciplinary management. Risk estimates can be used in discussion with patients.

ADVANCES IN KNOWLEDGE

The risk from RT prophylaxis is small, it is safer than indometacin and substantially overlaps with the range for no prophylaxis.

Risk of radiation-induced malignancy with heterotopic ossification prophylaxis: a case-control analysis

PURPOSE

To determine the risk of radiation-induced malignancy after prophylactic treatment for heterotopic ossification (HO).

METHODS AND MATERIALS

A matched case-control study was conducted within a population-based cohort of 3489 patients treated either for acetabular fractures with acetabular open reduction internal fixation or who underwent total hip arthroplasty from 1990 to 2009. Record-linkage techniques identified patients who were diagnosed with a malignancy from our state health registry. Patients with a prior history of malignancy were excluded from the cohort. For each documented case of cancer, 2 controls were selected by stratified random sampling from the cohort that did not develop a malignancy. Matching factors were sex, age at time of hip treatment, and duration of follow-up.

RESULTS

A total of 243 patients were diagnosed with a malignancy after hip treatment. Five patients were excluded owing to inadequate follow-up time in the corresponding control cohort. A cohort of 238 cases (control, 476 patients) was included. Mean follow-up was 10 years, 12 years in the control group. In the cancer cohort, 4% of patients had radiation therapy (RT), compared with 7% in the control group. Of the 9 patients diagnosed with cancer after RT, none occurred within the field. The mean latency period was 5.9 years in the patients who received RT and 6.6 years in the patients who did not. Median (range) age at time of cancer diagnosis in patients who received RT was 62 (43-75) years, compared with 70 (32-92) years in the non-RT patients. An ad hoc analysis was subsequently performed in all 2749 patients who were not matched and found neither an increased incidence of malignancy nor a difference in distribution of type of malignancy.

CONCLUSION

We were unable to demonstrate an increased risk of malignancy in patients who were treated with RT for HO prophylaxis compared with those who were not.

Cancer risk estimates from radiation therapy for heterotopic ossification prophylaxis after total hip arthroplasty

PURPOSE

Heterotopic ossification (HO) is a frequent complication following total hip arthroplasty. This study was conducted to calculate the radiation dose to organs-at-risk and estimate the probability of cancer induction from radiotherapy for HO prophylaxis.

METHODS

Hip irradiation for HO with a 6 MV photon beam was simulated with the aid of a Monte Carlo model. A realistic humanoid phantom representing an average adult patient was implemented in Monte Carlo environment for dosimetric calculations. The average out-of-field radiation dose to stomach, liver, lung, prostate, bladder, thyroid, breast, uterus, and ovary was calculated. The organ-equivalent-dose to colon, that was partly included within the treatment field, was also determined. Organ dose calculations were carried out using three different field sizes. The dependence of organ doses upon the block insertion into primary beam for shielding colon and prosthesis was investigated. The lifetime attributable risk for cancer development was estimated using organ, age, and gender-specific risk coefficients.

RESULTS

For a typical target dose of 7 Gy, organ doses varied from 1.0 to 741.1 mGy by the field dimensions and organ location relative to the field edge. Blocked field irradiations resulted in a dose range of 1.4-146.3 mGy. The most probable detriment from open field treatment of male patients was colon cancer with a high risk of 564.3 × 10(-5) to 837.4 × 10(-5) depending upon the organ dose magnitude and the patient's age. The corresponding colon cancer risk for female patients was (372.2-541.0) × 10(-5). The probability of bladder cancer development was more than 113.7 × 10(-5) and 110.3 × 10(-5) for males and females, respectively. The cancer risk range to other individual organs was reduced to (0.003-68.5) × 10(-5).

CONCLUSIONS

The risk for cancer induction from radiation therapy for HO prophylaxis after total hip arthroplasty varies considerably by the treatment parameters, organ site in respect to treatment volume and patient's gender and age. The presented risk estimates may be useful in the follow-up studies of irradiated patients.