Incidence of heterotopic ossification in direct anterior vs posterior approach to total hip arthroplasty: a retrospective radiographic review

"Heterotopic ossification after total hip arthroplasty through direct anterior approach without a dedicated orthopaedic table or direct lateral approach: a quasi-randomized single-center study"

INTRODUCTION

Heterotopic ossifications (HO) are common after total hip arthroplasty (THA). The invasiveness of surgical approaches plays a relevant role in HO development. The aims of this study were to assess the development of HO 6 months after THA through direct lateral approach (DLA) or direct anterior approach (DAA) without a dedicated orthopaedic table and to assess the clinical impact of HO.

METHODS

This is a single-center IRB-approved, quasi-randomized prospective cohort, observational imaging study. Fifty patients underwent primary THA through DLA and 50 through DAA. Age, sex, BMI and side of the affected hip were collected. At the 6 post-operative month the Harris Hip Score (HHS) and the presence of HO (scored through the Brooker classification system) were assessed.

RESULTS

There was no significant difference in the demographic data between groups. Operative time was significantly higher in the DAA group (72 ± 10 min vs. 58 ± 8 min: p < 0.03). At 6 post-operative months the incidence of HO was 14% in the DAA group and 32% in the DLA group (p = 0.02). Severe HO (Brooker 3-4) were significantly more common in the DLA group (p = 0.04). There was no significant difference in the HHS of patients with HO between the DAA and DLA groups. There was no association between poorer clinical outcomes and the severity of HO.

CONCLUSION

The DAA without a dedicated orthopaedic table is associated with a significant lower incidence of HO than the DLA 6 months after elective THA. Except for the surgical approach, no other factors correlated with the occurrence of HO. Even though a lower HHS was found with severe HO, the correlation between severity of HO and clinical outcomes did not reach statistical significance.

Incidence of heterotopic ossification following total hip arthroplasty by approach: a systematic review

BACKGROUND

Heterotopic ossification (HO) formation has been increasingly recognized as a complication of major orthopedic surgeries, particularly total hip arthroplasty (THA). Though, the overall incidence of HO following THA has been well-documented, it is often not reported by severity or by surgical approach.

QUESTIONS/PURPOSES

(1) What are the demographics of patients with HO? (2) What is the severity of HO following THA using the Brooker classification? (3) What is the incidence and class of HO following different THA approaches (anterior, posterior, posterolateral, anterolateral, superior, lateral, trans-gluteal)? (4) What are the number and training level of surgeons who performed each procedure?

METHODS

The PubMed, Embase, and Web of Science databases were queried, and PRISMA guidelines were followed. Qualitative and quantitative analyses were performed using Microsoft Excel.

RESULTS

We isolated 26 studies evaluating 6512 total hip arthroplasties (THA). The mean HO percentage overall was 28.8%, mostly Class I (54.2%) or Class II (29.6%). The highest percentage of HO was associated with the modified direct lateral (57.2%) and the traditional lateral (34.6%) approaches. The lowest HO percentages were identified following posterolateral (12.8%) and direct superior approaches (1%). Most studies reported a singular senior surgeon operating within the same approach for all patients.

CONCLUSIONS

The traditional lateral and modified direct lateral approaches to THA resulted in the highest percentage of HO postoperatively. However, most ossification cases were not clinically significant and did not strongly affect overall patient morbidity. Further studies are warranted to identify an association between severity of ossification and different arthroplasty approaches.

Direct anterior approach in total hip arthroplasty: influence of stem length on clinical and radiological outcomes at medium-term follow-up

PURPOSE

To evaluate the influence of short versus long stems implanted through a Direct Anterior Approach (DAA) on clinical and radiological outcomes in THA at medium-term follow-up (average follow-up of 44.8 months).

METHODS

167 consecutive total hip arthroplasties treating patients affected by primary hip osteoarthritis were retrospectively evaluated. A standard-length stem (H-MAXs) was used in 70 patients, while a short metaphyseal-fitting femoral stem (MINIMA) was used in 97 patients. The Harris Hip Score (HHS) and Forgotten Joint Score-12 (FJS) were used as outcomes measurements. Post-operatively, Engh's score and Brooker classification were analyzed at 6 months, 1 year and every 2 years until the final FU. The correct size of the implant was evaluated determining the canal fill index (CFI), and all undersized stems were classified according to Magra classification.

RESULTS

The average HHS was 83 ± 13.4 in the standard stems group and 87 ± 14.1 for short stems group (p = 0.148). The average FJS was 87.9 ± 15.2 for patients in the standard stems group and 84.5 ± 17.7 with no significant differences (p = 0.327). None of the stems showed radiographic signs of instability (standard stems mean Engh's score: 19.25 versus short stems mean Engh's score: 19.50-p = 0.41). According to Brooker classification, no significant difference in severity was found using different stems (p = 0.715). A high rate of undersized stems was found (standard stems 24%-short stems 25%) but without statistical difference between groups (p = 0.078), while a different trend in malposition following the recent classification proposed by Magra et al. was observed evaluating all undersized stems (p = 0.0387).

CONCLUSIONS

Both groups achieved good and comparable patient-reported outcome measurements (PROMs) and radiographic stability with fixation observed by bone ingrowth. A high rate of undersized stems was found with a correlation between femoral stem length and specific pattern of malposition. Malalignment in Varus was frequent in shorter stems in contact proximally with medial calcar and distally with lateral cortex, while a uniform undersizing was observed for longer ones with a continuous margin around the stem. However, the stems never presented progressive radiolucent lines over the whole surface of the stem.

Role of aspirin in the prevention of heterotopic ossification following total hip replacement: a systematic review and meta-analysis

BACKGROUND

To systematically investigate if aspirin (ASA), used as venous thromboembolism (VTE) prophylaxis, plays a role in the prevention of heterotopic ossification (HO) following total hip arthroplasty (THA) and if ASA dosage impacted the rate of HO.

METHODS

Eligible studies published from January 2000 to July 2022 were identified from the computerized searching of PubMed, Scopus and Web of Science. HO was defined according to Brooker Classification. Pooled risk ratios (OR) and 95% confidence interval (CI) were estimated under a random-effect model. Additionally, combined HO incidences were compared according to ASA dosage (a regular dose of 325 bid vs. a low dose of 81 mg bid/162 mg qd).

RESULTS

Thirteen studies were included. ASA administered for VTE prophylaxis was significantly associated with a reduced risk of all-grade HO following THA (univariate, OR: 0.50, 95% CI: 0.34-0.74, P < 0.001; multivariate, OR: 0.60, 95% CI: 0.49-0.73, P < 0.001). Similar results could be observed for high-grade HO (univariate, OR: 0.57, 95% CI: 0.36-0.89, P = 0.015; multivariate, OR: 0.50, 95% CI: 0.27-0.92, P = 0.026). There was a non-significant trend towards a higher incidence of HO formation for low-dose ASA (31%, 95% CI: 29-34%), compared with regular-dose ASA (21%, 95% CI: 11-33%) (P = 0.069 under test of interaction).

CONCLUSIONS

ASA can be an effective option for HO prophylaxis. More well-designed trials with long-term follow-ups are encouraged to confirm the current findings and to investigate the effect of ASA dosage on HO reduction.

Heterotopic Ossification After Modern Total Hip Arthroplasty: Predisposing Factors, Prophylaxis, and Surgical Treatment

Heterotopic ossification (HO) is a common radiographic finding and potentially serious complication after modern total hip arthroplasty. Although historically associated with the posterolateral approach, HO has been noted in 10% to 40% of patients having direct anterior or anterior-based muscle sparing approaches. The available data are uncertain whether robotic arm-assisted procedures are associated with this complication. Current prophylaxis for patients considered high risk of this complication includes postoperative, nonsteroidal, anti-inflammatory medication for several weeks or low-dose perioperative irradiation. The surgical treatment of symptomatic HO associated with severely restricted motion or ankylosis of the hip should be individualized but may include wide excision of bone, acetabular revision to prevent instability, and prophylaxis to prevent recurrence.

Heterotopic Ossification in Hip Arthroscopy

Introduction  Hip arthroscopy is a rising surgical technique due to the increase in hip diseases, especially femoroacetabular impingement. One of the several complications related to such procedures is heterotopic ossifications (HO). The aim of this study is to describe the prevalence of HO after hip arthroscopy in a series of patients with femoroacetabular impingement and to compare its preoperative and intraoperative variables with a matched control group of patients without HO. Methods  All patients who underwent hip arthroscopy for femoroacetabular impingement between 2010 and 2017 with a minimum follow-up of 2 years were included in this analysis. Radiographic examinations were recorded to select cases with HO. A case-control analysis was performed comparing preoperative and intraoperative variables between cases with HO and a matched control group without HO. Results  A total of 700 cases were included in the analysis. HO was found in 15 (2.14%) of subjects. Cases with HO showed more severe cartilage injuries, less cam morphology ratio, and a higher proportion of partial labrectomies than the control group. No significant differences were observed in preoperative hip pain or function between groups. Conclusions  The prevalence of HO after hip arthroscopy in subjects with femoroacetabular impingement was 2.14%. Cases with HO had more severe cartilage injuries, lower ratio of cam morphology, and higher proportion of partial labrectomies than the control cases without HO. Level of Evidence  Level III.

The development of a mouse model to investigate the formation of heterotopic ossification

BACKGROUND

Muscle injury and concomitant bone injury are important drivers to induce heterotopic ossification (HO). However, the related roles of muscle and concomitant bone injury in HO formation are still unclear. This study aims to develop a mouse model through the combination of hindlimb amputation (Am) and cardiotoxin (CTX) injection to investigate the mechanism of HO formation.

METHOD

The mice were randomly divided into Am group (Am of right hindlimb, n = 12), CTX group (CTX injection in the calf muscle of left hindlimb, n = 12) and Am + CTX group (the combination of Am of right hindlimb and CTX injection of left hindlimb, n = 18). MicroCT was used to evaluate the incidence of HO. Histology was used to investigate the progression of HO.

RESULTS

The MicroCT showed that only Am or CTX injection failed to induce HO while the combination of Am and CTX injection successfully induced HO. The incidence of HO was significant in Am + CTX group on day 7 (0% vs 0% vs 83.3%, p = 0.001) and day 14 (0% vs 0% vs 83.3%, p = 0.048). HO was located on the left hindlimb where CTX was injected. Moreover, the bone volume and bone density on day 14 were higher than those on day 7 in Am + CTX group. Histology revealed the evidence of calcification and expression of osteogenic markers in calcification sites in Am + CTX group.

CONCLUSION

In summary, the combination of Am and CTX injection could successfully induce dystrophic calcification/HO, which occurs in the location of muscle injury.

Reducing Complications and Enhancing the Functional Outcome of Total Hip Arthroplasty without Increasing Operation Time by Repairing Posterolateral Soft Tissues

Total hip arthroplasty (THA) surgeries are increasing annually. Despite continuous improvements in the surgical technique and prosthetic design, there is still no consensus on whether it is beneficial to reconstruct the posterolateral soft tissue. This paper systematically reviews randomized controlled trials (RCTs) addressing the efficacy and safety of posterolateral soft tissue during total hip replacement to provide evidence-based guidance for clinical practice. We searched PubMed, EMBASE, Cochrane Library, CNKI, and Wanfang databases for RCTs. Experimental results show that repair of the posterolateral soft tissue can reduce complications and improve the function of total hip arthroplasty without increasing operative time.

Heterotopic ossification after total hip arthroplasty: radiological comparison between a direct anterior approach without an orthopaedic table and a posterior approach

INTRODUCTION

Heterotopic ossification (HO) occurs in almost ⅓ of total hip arthroplasties (THAs). A direct anterior approach (DAA) with an orthopaedic table is less likely to cause HO than a posterior approach. Without an orthopaedic table, the exposure of the femur requires additional soft tissue release. Soft tissue trauma leads to the production of HO inductors. Our study evaluated the incidence of HO 6 months after THA and compared the results between DAAs without an orthopaedic table and posterior approaches.

METHODS

Retrospectively, 164 consecutive, primary THAs were included: 76 through a posterior approach and 88 through a DAA. The main objective was to measure the presence of HO on pelvis radiography 6 months after surgery.

RESULTS

The incidence of HO was significantly higher in the DAA group than in the posterior approach group (47.7% vs. 27.6%, respectively; p < 0.01). The overall incidence of HO was 38.4%. No significant difference was found between the 2 approaches regarding the severity of HO. No significant risk factor for HO was identified other than the surgical approach.

DISCUSSION

In our study, the incidence of HO after THA in patients undergoing DAA without an orthopaedic table was higher than in patients undergoing a posterior approach after 6 months of follow-up. This result is closely related to the surgical trauma. It suggests that the minimally invasive feature of a surgical approach cannot be dissociated from the overall conditions in which it is performed.

[Research progress of traumatic heterotopic ossification]

OBJECTIVE

To review and evaluate the research progress of traumatic heterotopic ossification (HO).

METHODS

The domestic and foreign related research literature on traumatic HO was widely consulted, and its etiology, pathogenesis, pathological progress, diagnosis, prevention, and treatment were summarized.

RESULTS

Traumatic HO is often caused by severe trauma such as joint operation, explosion injury, nerve injury, and burn. At present, it is widely believed that the occurrence of traumatic HO is closely related to inflammation and hypoxia. Oral non-steroidal anti-inflammatory drugs and surgery are the main methods to prevent and treat traumatic HO.

CONCLUSION

Nowadays, the pathogenesis of traumatic HO is still unclear, the efficiency of relevant prevention and treatment measures is low, and there is a lack of specific treatment method. In the future, it is necessary to further study the pathogenesis of traumatic HO and find specific prevention and treatment targets.

Heterotopic Ossification Following Direct Anterior Total Hip Arthroplasty With and Without Postoperative Analgesic Nonsteroidal Anti-inflammatories

BACKGROUND

Heterotopic ossification (HO) can result in poorer clinical outcomes following total hip arthroplasty (THA). Multiple modes of intervention have been evaluated for HO prevention, including the use of nonsteroidal anti-inflammatories. Additionally, multimodal pain management strategies including celecoxib have become more prominent. Therefore, this study aims to evaluate the influence of celecoxib as part of postoperative analgesia on the risk of developing HO following the direct anterior approach (DA) for THA.

METHODS

A retrospective query identified primary DA THAs performed by a single surgeon between 2013 and 2020. Patients were grouped according to those who received 3 weeks celecoxib upon discharge, and those who did not. Radiographs were used to categorize patients according to the Brooker classification system for HO. Preoperative and 2-week, 6-week, 3-month, and 1-year postoperative X-rays were evaluated.

RESULTS

A total of 688 DA THAs were included, demonstrating a 9.6% (n = 66) incidence of HO with Brooker classification: 1: 5.7% (n = 39); 2: 2.6% (n = 18); 3: 1.2% (n = 8); and 4: 0.1% (n = 1). Patients who did not receive celecoxib had a 14.3% (52/364) rate of HO following THA (odds ratio 4.53, P < .001) vs only 4.3% (14/324) in the celecoxib group (odds ratio 0.22, P < .001). Overall, 9 patients (1.3%) went on to develop significant HO (Booker 3 or greater): 8 (2.2%) in the control group and 1 (0.3%) in the celecoxib group (P < .001).

CONCLUSION

Our findings suggest a significant reduction in the formation of HO following DA THA when using postoperative analgesic celecoxib as part of a multimodal pain protocol. Future prospective randomized studies are needed to identify ideal dosage, duration, and formulation to reduce the risk of HO while optimizing multimodal pain management.

Evaluation of Direct Anterior Approach for Revision Total Hip Arthroplasty: A Systematic Review

The direct anterior approach (DAA) is an established approach for total hip arthroplasty (THA) but has been sparingly tried for revisions. The purpose of this study was to examine the available literature in order to consolidate information available on revision THA using the DAA. A PubMed, Embase, and Scopus search was performed using relevant keywords. Studies reporting on patients undergoing revision THA using DAA were included for analysis. In a review of the literature, nine studies matched the pre-decided inclusion criteria with 319 hip joints undergoing revision THA. Mean follow-up of all included studies was 34 months. The indications of revision after primary THA in decreasing order were aseptic loosening (53%), prosthetic joint infection (20.7%), peri-prosthetic fracture (16.9%), dislocation (7.2%), psoas impingement (1.9%), polyethylene wear (1.2%), pain (0.6%), and instability (0.3%). Of the 319 revisions evaluated, 107 underwent a stem revision, 142 underwent cup revision, 49 underwent a combined revision, and 21 underwent isolated liner/head change. A statistically significant improvement in functional score (P<0.05) was observed for all studies reporting on functional outcomes. A low complication rate (51/319, 16.0%), which includes dislocation (12), infection (12), loosening of the acetabular shell (5), peri-prosthetic fractures (6), haematoma (4), and transient nerve palsy (6), was reported. Based on available level III-IV evidence, DAA appears to be a reliable alternative for revision of the failed hip arthroplasty with acceptable complication rates. Evidence of a higher quality is needed to further characterize its role in revision scenarios.

Simplified biplanar classification for heterotopic ossification is more predictive of patient-reported outcomes than the Brooker classification after anterior total hip arthroplasty

BACKGROUND

Heterotopic ossification (HO) commonly occurs after total hip arthroplasty (THA) and can adversely impact clinical outcomes. The purpose of this study is to propose a more reliable HO grading method that is better predictive of patient-reported outcomes (PROs) after THA than the Brooker classification.

METHODS

513 THAs (62 ± 10 years old) were reviewed. The incidence and grade of HO was evaluated using the Brooker grading system and a simplified biplanar classification system (grade 1: ⩾1 cm between bone on both anteroposterior and lateral views, grade 2: <1 cm between bone on either view). The modified Harris Hip Score (mHHS), Forgotten Joint Score (FJS), and visual analogue scale (VAS) for pain were collected at minimum of 2 years after surgery and were compared between HO grades using multiple regression models.

RESULTS

The incidence of HO varied by Brooker grade (grade 1, 23.4%; grade 2, 22.4%; grade 3, 7.2%; grade 4, 0%) and biplanar grade (grade 1: 45.6%; grade 2: 7.4%). The biplanar classification demonstrated higher interobserver reliability than the Brooker classification (κ = 0.95 and 0.91, respectively). Brooker grade 3 HO decreased the mHHS by 6.5 (standard error: 2.7) but did not have a significant effect on FJS or VAS. Biplanar grade 2 HO decreased the mHHS by 9.9 (standard error: 2.7), the FJS by 12.9 (standard error: 4.51) and increased the VAS pain score by 0.81 (standard error: 0.35). The Cox test was used to compare the fit of regression models and determined the biplanar classification was a significantly better predictor than the Brooker classification (p < 0.001).

CONCLUSIONS

Biplanar grade 2 HO had a significant negative influence on PROs. Contrary to previous literature, these results show clinical significance of non-bridging HO. Compared with the Brooker classification, the biplanar classification has greater interobserver reliability and is more predictive of outcomes after THA.

Acetabular Exposure Is Enhanced With Self-Retaining Retractors During Direct Anterior Total Hip Arthroplasty

Acetabular exposure for direct anterior (DA) total hip arthroplasty (THA) can be performed using hands-free, self-retaining retractors. No current study quantitatively compares this self-retaining technique with the traditional manual technique. In 65 consecutive DA THA hips, two "best-view" digital photographs were taken of the exposure-one using Charnley/self-retaining retractors and one using a traditional three-retractor manual technique. Percent exposure of the polyethylene liner was calculated. Percent acetabular exposure averaged 80.0% using the Charnley/self-retaining technique, compared with 73.1% using the manual technique (P=.0002). A hands-free technique provides superior acetabular exposure compared with the manual technique. Increasing body mass index predicts decreasing exposure with both techniques. [Orthopedics. 2021;44(2):e309-e313.].

Minimizing complications in bikini incision direct anterior approach total hip arthroplasty: A single surgeon series of 865 cases

PURPOSE

The purpose of this study was to report all complications during the first consecutive 865 cases of bikini incision direct anterior approach (DAA) total hip arthroplasty (THA) performed by a single surgeon. The secondary aims of the study are to report our clinical outcomes and implant survivorship. We discuss our surgical technique to minimize complication rates during the procedure.

METHODS

We undertook a retrospective analysis of our complications, clinical outcomes and implant survivorship of 865 DAA THA's over a period of 6 years (mean = 3.9yrs from 0.9 to 6.8 years).

RESULTS

The complication rates identified in this study were low. Medium term survival at minimum 2-year survival and revision as the end point, was 99.53% and 99.84% for the stem and acetabular components respectively. Womac score improved from 49 (range 40-58) preoperatively to 3.5(range 0-8.8) and similarly, HHS scores improved from 53(range 40-56) to 92.5(range 63-100) at final follow-up (mean = 3.9 yrs) when compared to preoperative scores.

CONCLUSIONS

These results suggest that bikini incision DAA technique can be safely utilised to perform THA.

The Impact of Heterotopic Ossification on Self-Reported Outcomes After Total Hip Arthroplasty Using the Direct Anterior Approach

BACKGROUND

Heterotopic ossification (HO) is a known finding after total hip arthroplasty (THA) that potentially affects clinical outcomes. The incidence of HO is related to various factors, including soft-tissue trauma, postoperative medication, surgical approach, and the surgeon's experience. Because use of the direct anterior approach (DAA) is gaining popularity, we aimed (1) to determine the incidence of HO after DAA-THA and (2) to evaluate the impact of HO on patient-reported outcomes (PROs).

METHODS

We retrospectively reviewed 401 THAs (67 ± 10 years old, 210 men). The incidence and grade of HO were evaluated using the Brooker classification with anteroposterior and lateral radiographs. PROs were collected with use of the Oxford Hip Score (OHS) and the Core Outcome Measures Index (COMI)-Hip and were correlated with HO grades using generalized multiple regression models.

RESULTS

The incidence of HO was 29.9% on the anteroposterior radiographic views (Brooker grade 1, 14.5%; grade 2, 11.1%; grade 3, 2.7%; and grade 4, 0.57%); the lateral radiographic views detected 9% additional HO when compared with the anteroposterior radiographs alone (Brooker grade 1, 8%, and grade 2, 1%). HO was more frequent in men. The American Society of Anesthesiologists (ASA) grade, age in women, and higher body mass index (BMI) in men were associated with higher HO grades. A transverse "bikini" incision was associated with a lower rate (4%) of Brooker grades 3 and 4 HO when compared with a longitudinal incision (12%). A Brooker grade of 0 to 3 HO did not impact outcomes. Only Brooker grade-4 HO was associated with significantly worse PROs; however, pain was not affected.

CONCLUSIONS

Low-grade HO after DAA-THA is not uncommon, and its rate is underestimated when anteroposterior radiographic views are evaluated without lateral views. The risk factors for developing HO in our cohort were an ASA grade of >3, male sex (especially with a high BMI), older age in women, and use of longitudinal incisions. With use of the bikini incision, patients had lower rates of severe HO, but mostly senior surgeons with more experience performed their surgery. Age, ASA grade, experience level of the surgeon, and Brooker grade-4 HO all had a significant influence on PROs. Clinically important HO (Brooker grade 4) remains rare after DAA-THR.

LEVEL OF EVIDENCE

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

Direct anterior approach for femoral component revision: Surgical technique for extended trochanteric osteotomy and anterior cortical window

Objective

Direct anterior approach (DAA) is becoming a popular option for both primary and revision total hip arthroplasty (THA). Adequate exposure is crucial in the setting of revision THA. The purpose of this article is to describe two different techniques for expanded femoral exposure through the DAA, the anterior extended trochanteric osteotomy and anterior cortical window.

Methods

Extensile exposure were carried out in cadavers, using the contralateral hip as a control. The exposure and technical viability were assessed.

Results

It was demonstrated that both extensile techniques can be carried out safely.

Conclusions

Extensile exposures including femoral osteotomies can be safely carried out for revision THA via DAA.

Dead muscle tissue promotes dystrophic calcification by lowering circulating TGF-β1 level

Aims

Dystrophic calcification (DC) is the abnormal appearance of calcified deposits in degenerating tissue, often associated with injury. Extensive DC can lead to heterotopic ossification (HO), a pathological condition of ectopic bone formation. The highest rate of HO was found in combat-related blast injuries, a polytrauma condition with severe muscle injury. It has been noted that the incidence of HO significantly increased in the residual limbs of combat-injured patients if the final amputation was performed within the zone of injury compared to that which was proximal to the zone of injury. While aggressive limb salvage strategies may maximize the function of the residual limb, they may increase the possibility of retaining non-viable muscle tissue inside the body. In this study, we hypothesized that residual dead muscle tissue at the zone of injury could promote HO formation.

Methods

We tested the hypothesis by investigating the cellular and molecular consequences of implanting devitalized muscle tissue into mouse muscle pouch in the presence of muscle injury induced by cardiotoxin.

Results

Our findings showed that the presence of devitalized muscle tissue could cause a systemic decrease in circulating transforming growth factor-beta 1 (TGF-β1), which promoted DC formation following muscle injury. We further demonstrated that suppression of TGF-β signalling promoted DC in vivo, and potentiated osteogenic differentiation of muscle-derived stromal cells in vitro.

Conclusion

Taken together, these findings suggest that TGF-β1 may play a protective role in dead muscle tissue-induced DC, which is relevant to understanding the pathogenesis of post-traumatic HO.

Cite this article: Bone Joint Res 2020;9(11):742–750.

Local injection of a hexametaphosphate formulation reduces heterotopic ossification in vivo

Heterotopic ossification (HO), the pathological formation of ectopic bone, is a debilitating condition which can cause chronic pain, limit joint movement, and prevent prosthetic limb fitting. The prevalence of this condition has risen in the military population, due to increased survivorship following blast injuries. Current prophylaxes, which aim to target the complex upstream biological pathways, are inconsistently effective ​and have a range of side-effects that make them unsuitable for combat-injured personnel. As such, many patients must undergo further surgery to remove the formed ectopic bone. In this study, a non-toxic, U.S. Food and Drug Administration (FDA) -approved calcium chelator, hexametaphosphate (HMP), is explored as a novel treatment paradigm for this condition, which targets the chemical, rather that biological, ​bone formation pathways. This approach allows not only prevention of pathological bone formation ​but also uniquely facilitates reversal, which current drugs cannot achieve. Targeted, minimally invasive delivery is achieved by loading HMP into an injectable colloidal alginate. These formulations significantly reduce ​the length of the ectopic bone formed in a rodent model of HO, with no effect on the adjacent skeletal bone. This study demonstrates the potential of localized dissolution as a new treatment ​and an alternative to surgery ​for pathological ossification and calcification conditions.

Ten-Year Experience With the Anterior Approach to Total Hip Arthroplasty at a Tertiary Care Center

BACKGROUND

The anterior approach (AA) to total hip arthroplasty (THA) has advantages for patients and healthcare providers. However, some studies have reported high rates of adverse events when introducing AA-THA. This was not consistent with our center's experience, where 4 senior surgeons safely introduced AA-THA into practice. The purpose of this study is to define the adverse event rates associated with the introduction of AA-THA by a group of experienced surgeons at a single tertiary care center and define experiential factors that may modify adverse event rates.

METHODS

Retrospective review of prospectively collected data for an observational cohort of all patients undergoing a THA between 2006 and 2017 was conducted. Four senior surgeons at a single institution operated on 1087 primary elective hips using AA-THA.

RESULTS

Between 2006 and 2016, AA-THA rose from 1.5% to 53.2% of annual THA. Adverse events included intraoperative events, early postoperative periprosthetic fractures, dislocation, implant failure, early infection, and wound complications. We observed an overall 90-day adverse event rate of 6.4% (of 1087 hips). The adverse event rate was 41.6% (of 12 hips) in the first 12 months of the study period and 3.6% (of 166 hips) in the final 12 months of the study period reviewed. Sixty hips (5.5%) required a reoperation with or without revision of components, 1 (8.3%) in the first 12 months of the study period and 1 (0.6%) in the final 12 months of the study period. Infection and wound complications were the most common causes of reoperation at 1.8% for all cases (20 hips). Higher rates of adverse events are associated with early procedures (n ≤ 15) for all surgeons but showed no statistically significant impact on 5-year survival rate.

CONCLUSION

Our experience demonstrates that AA-THA can be introduced into practice with an acceptable adverse event rate when compared with other approaches to THA. As expected the incidence of adverse events is higher in the early part of the learning curve. Surgeon mentoring in the first 20 cases should be considered to minimize risk of adverse events.

LEVEL OF EVIDENCE

Therapeutic Level III.

The Reduction of Heterotopic Ossification Incidence After Hip Arthroscopy in Patients Treated With Selective Cyclooxygenase 2 Inhibitor (Celecoxib)

PURPOSE

To evaluate the effectiveness of celecoxib, a selective cyclooxygenase 2 inhibitor, in reducing heterotopic ossification (HO) after hip arthroscopic surgery and to evaluate celecoxib's impact on clinical outcomes.

METHODS

We performed a retrospective review of patients who received hip arthroscopy performed by the same surgeon between January 1, 2012, and December 31, 2016. Patients who had an allergy to sulfa drugs, had pre-existing HO or previous surgery on the operative side, or failed to complete radiographic follow-up at 6 months postoperatively were excluded. Patients in the treatment group received 400 mg of celecoxib postoperatively for 6 weeks, whereas the control group received no postoperative celecoxib. The incidence of HO was assessed using anteroposterior radiographs obtained at 6 months, 1 year, and 2 years postoperatively. Patients completed the International Hip Outcome Tool 33 survey, and the proportion of patients who met the minimal clinically important difference, substantial clinical benefit (SCB), and absolute SCB was calculated.

RESULTS

A total of 559 patients were identified. After application of the exclusion criteria, 454 patients were included in the study (211 in control group and 243 in treatment group). The overall incidence of HO was 20.3% (n = 92). The treatment group had a significantly lower incidence of HO at 6 months (P = .006), 1 year (P < .001), and 2 years (P = .008) postoperatively. At 2 years postoperatively, the treatment group had a significantly higher International Hip Outcome Tool 33 score on average: 64.2 versus 57.3 (P = .023). No significant difference in the proportion of patients reaching the minimal clinically important difference, SCB, or absolute SCB was found at any of the postoperative time points.

CONCLUSION

The findings of this study suggest that a prophylactic treatment regimen of 400 mg of celecoxib once daily for 6 weeks significantly reduces the incidence of HO formation after hip arthroscopic surgery; however, it did not impact clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective, comparative case-control study.

Heterotopic ossification and clinical results after total hip arthroplasty using the anterior minimally invasive and anterolateral approaches

INTRODUCTION

Total hip arthroplasty (THA) is considered the gold standard in the treatment of advanced osteoarthritis of the hip. The aim of this study was to compare the incidence of heterotopic ossification (HO), the quality of life and the function in two groups of patients who underwent total hip arthroplasty (THA), performed using the anterior minimally invasive (MIS) and the anterolateral approaches.

MATERIAL AND METHODS

Retrospective analysis of 597 patients who underwent THA in 2009-2013 was performed. In all 597 cohort data on medical history were retrieved. HO occurrence was recorded for 331 patients and was evaluated based on Brooker's scale in the X-ray scan. Functional and quality of life scores were obtained for 238 patients. The following scales were used for the survey: Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index, Visual Analogue Scale, and Hip and Knee Arthroplasty Satisfaction Scale.

RESULTS

Patients operated on from the MIS approach had statistically significantly (p < 0.05) better results with all the clinical scales used, except the Visual Analogue Scale (p > 0.05). HO was slightly more common after the MIS approach (52.5%) compared to the anterolateral approach (49.76%), though the difference was not statistically significant (p > 0.05).

CONCLUSIONS

The MIS approach was associated with better clinical and functional outcomes. In the aspect of HO, we were not able to show the superiority of the MIS approach in terms of incidence.

Inflammation in Fibrodysplasia Ossificans Progressiva and Other Forms of Heterotopic Ossification

PURPOSE OF REVIEW

Heterotopic ossification (HO) is associated with inflammation. The goal of this review is to examine recent findings on the roles of inflammation and the immune system in HO. We examine how inflammation changes in fibrodysplasia ossificans progressiva, in traumatic HO, and in other clinical conditions of HO. We also discuss how inflammation may be a target for treating HO.

RECENT FINDINGS

Both genetic and acquired forms of HO show similarities in their inflammatory cell types and signaling pathways. These include macrophages, mast cells, and adaptive immune cells, along with hypoxia signaling pathways, mesenchymal stem cell differentiation signaling pathways, vascular signaling pathways, and inflammatory cytokines. Because there are common inflammatory mediators across various types of HO, these mediators may serve as common targets for blocking HO. Future research may focus on identifying new inflammatory targets and testing combinatorial therapies based on these results.

Severity of heterotopic ossification in patients following surgery for hip fracture: a retrospective observational study

BACKGROUND

Heterotopic ossification (HO) is a relatively common complication following hip surgery treated with open reduction and internal fixation, total arthroplasty or hemiarthroplasty. Development of HO after hip surgery is an important clinical issue as it can affect functional status. We aimed to determine whether there was association between severity of heterotopic ossification about the hip and the interval between the time of hip fracture and surgery.

MATERIALS AND METHODS

Our retrospective study included 151 patients (age range 33-95 years) treated for hip fractures by hemiarthroplasty. Medical records were reviewed for time interval to surgery, laterality, surgical approach, and patient age. Patients who had any post-operative complications were excluded. Radiographs were semiquantitatively assessed for the degree of heterotopic ossification based on Brooker Classification (5-point scale). Statistical analysis was performed utilizing Chi-square, Kruskal-Wallis, and Score tests, and also a proportional odds model (significance level set at 0.05).

RESULTS

Thirty eight patients had no heterotopic ossification, 43 had class 1, 55 had class 2, and 15 had class 3 or greater heterotopic ossification. The majority of patients (59.6%) had surgery within 2 days of acute injury. Severe heterotopic ossification (HO 3+) was associated with the longer interval between the time of acute hip fracture and surgery (median 6 days) vs. median 2 days in all other groups (HO classes 0-2) (p = 0.0015). The odds ratio and 95% CI for one level higher HO class was 1.296 (1.152, 1.459), which meant that the odds of having HO class one level higher increased by about 29.6% for every one-day increase in the days to surgery. No significant association was found for other variables.

CONCLUSION

Class 3 or greater HO was associated with longer time interval between time of acute hip fracture and surgery compared to all other groups (HO class 0-2).

The minimalinvasive direct anterior approach in aseptic cup revision hip arthroplasty: a mid-term follow-up

INTRODUCTION

The minimally invasive direct anterior approach (DAA) is an established approach for primary total hip arthroplasty (THA). The complication rates in hip revision arthroplasty are much higher in comparison with primary THA. A right positioning of the implants and a soft tissue, especially the abductors spearing approach, is important to get good functional results and low complication rates. The aim of this study was to show the clinical and radiological outcome of isolated revision hip arthroplasty of the cup by using the DAA.

MATERIALS AND METHODS

Aseptic cup revisions were carried out in 48 patients using the DAA. A decision to exchange the stem was made intraoperatively in seven cases. Complications, radiological and functional outcome were assessed. All of the data were collected retrospectively. The mean follow-up period was 65 months.

RESULTS

In most of the cases the standard DAA was used. A proximal extension was nescessary in 15 patients (31%). The mean cup inclination angle after revision was 44° (min. 25°, max. 62°). Six implants (12.5%) were located outside of the Lewinnek safe zone. The centers of rotation of the revision implants were a mean of 0.6 cm superior (min. 0, max. 2.2 cm) and 0.5 cm lateral (min. 0.2 cm, max 1.2 cm) in comparison with the center of rotation in the healthy hip on the contralateral side. Harris Hip Score improved significantly from 50 to 91 (P = 0.03). Complications noted consisted of two periprosthetic infections (4.2%), one aseptic cup loosening (2.1%), two hematomas requiring revision (4.2%), and one case each of femoral nerve injury, lower-leg venous thrombosis, and pneumonia. No dislocations were observed and there were no cases of heterotopic ossification based on the Brooker classification. No persistent damage of the nervus cutaneus femoris lateralis was found at the follow-up examinations.

CONCLUSIONS

The DAA represents a feasible option in hip revision arthroplasty. Anatomic reconstruction of the cup is reproducibly possible. Good medium-term results can also be achieved. Particularly in relation to dislocation, the complication rates are low. Due to the learning curve, the DAA should only be used in hip revision arthroplasty by those with sufficient experience in primary THA. Adequate data regarding stem revisions through the DAA are not available at the moment.

Influence of surgical approach on complication risk in primary total hip arthroplasty

Background and purpose - Systematic comparisons of anterior approach (A) versus posterior approach (P) in primary total hip arthroplasty (THA) have largely focused on perioperative outcomes. In this systematic review with meta-analysis, we compared complication risk of A versus P in studies of primary THA with at least 1-year mean follow-up. Patients and methods - We performed a systematic review of prospective and retrospective studies with at least 1-year mean follow-up that reported complications of A and P primary THA. Complications included infection, dislocation, reoperation, thromboembolic event, heterotopic ossification, wound complication, fracture, and nerve injury. Random effects meta-analysis was used for all outcomes. Complication risk was reported as rate ratio (RR) to account for differential follow-up durations; values >1 indicated higher complication risk with A and values <1 indicated lower risk with A. Results - 19 studies were included; 15 single-center comparative studies with 6,620 patients (2,278 A; 4,342 P) and 4 multicenter registries with 157,687 patients (18,735 A; 138,952 P). Median follow-up was 16 (12-64) months) with A and 18 (12-110) months with P. Anterior approach was associated with lower rate of infection (RR =0.55, p = 0.002), dislocation (RR =0.65, p = 0.03), and reoperation (RR =0.84, p < 0.001). No statistically significant differences were observed in rate of thromboembolic event (RR =0.59, p = 0.5), heterotopic ossification (RR =0.63, p = 0.1), wound complication (RR =0.93, p = 0.8), or fracture (RR =1.0, p = 0.9). There was a higher rate of patient-reported nerve injury with A (RR =2.3, p = 0.01). Interpretation - Comparing A with P in primary THA, A was associated with lower risk of reoperation, dislocation, and infection, but higher risk of patient-reported nerve injury.

Total hip arthroplasty for posttraumatic osteoarthritis following acetabular fracture: A systematic review of characteristics, outcomes, and complications

PURPOSE

Posttraumatic arthritis (PTA) may develop years after acetabular fracture, hindering joint function and causing significant chronic musculoskeletal pain. Given the delayed onset of PTA, few studies have assessed outcomes of delayed total hip arthroplasty (THA) in acetabular fracture patients. This study systematically reviewed the literature for outcomes of THA in patients with PTA and prior acetabular fracture.

METHODS

Pubmed, EMBASE, SCOPUS, and Cochrane library were searched for articles containing the keywords "acetabular", "fracture", "arthroplasty", and "post traumatic arthritis" published between 1995 and August 2017. Studies with less than 10 patients, less than 2 years of follow-up, conference abstracts, and non-English language articles were excluded. Data on patient demographics, surgical characteristics, and outcomes of delayed THA, including implant survival, complications, need for revision, and functional scores, was collected from eligible studies.

RESULTS

With 1830 studies were screened and data from 10 studies with 448 patients were included in this review. The median patient age on date of THA was 51.5 years, ranging from 19 to 90 years. The median time from fracture to THA was 37 months, with a range of 27-74 months. Mean follow-up times ranged from 4 to 20 years. The mean Harris hip scores (HHS) improved from 41.5 pre-operatively, to 87.6 post-operatively. The most prevalent postoperative complications were heterotopic ossification (28%-63%), implant loosening (1%-24%), and infection (0%-16%). The minimum 5-year survival of implants ranged from 70% to 100%. Revision rates ranged from 2% to 32%.

CONCLUSION

Despite the difficulties associated with performing THA in patients with PTA from previous acetabular fracture (including soft tissue scarring, existing hardware, and acetabular bone loss) and the relatively high complication rates, THA in patients with PTA following prior acetabular fracture leads to significant improvement in pain and function at 10-year follow-up. Further high quality randomized controlled studies are needed to confirm the outcomes after delayed THA in these patients.

Does Surgical Approach Affect Outcomes in Total Hip Arthroplasty Through 90 Days of Follow-Up? A Systematic Review With Meta-Analysis

BACKGROUND

The choice between anterior approach (AA) and posterior approach (PA) in primary total hip arthroplasty (THA) is controversial. Previous reviews have predominantly relied on data from retrospective studies.

METHODS

This systematic review included prospective studies comparing postoperative outcomes through 90 days of AA vs PA in primary THA. Outcomes were pain severity, narcotic usage, hip function using Harris Hip Score, and complications. Random effects meta-analysis was performed for all outcomes. Efficacy data were reported as standardized mean difference (SMD) where values of 0.2, 0.5, 0.8, and 1.0 were defined as small, medium, large, and very large effect sizes, respectively. Complications were reported as the absolute risk difference (RD) where a positive value implied higher risk with AA and a lower value implied lower risk with AA.

RESULTS

A total of 13 prospective comparative studies (7 randomized) with patients treated with AA (n = 524) or PA (n = 520) were included. The AA was associated with lower pain severity (SMD = -0.37, P < .001), lower narcotic usage (SMD = -0.36, P = .002), and improved hip function (SMD = 0.31, P = .002) compared to PA. No differences between surgical approaches were observed for dislocation (RD = 0.2%, P = .87), fracture (RD = 0.2%, P = .87), hematoma (RD = 0%, P = .99), infection (RD = 0.2%, P = .85), thromboembolic event (RD = -0.9%, P = .42), or reoperation (RD = 1.3%, P = .26). Conclusions of this study were unchanged when subjected to sensitivity analyses.

CONCLUSION

In this systematic review and meta-analysis of prospective studies comparing postoperative outcomes through 90 days of AA vs PA in primary THA, patients treated with AA reported less pain, consumed fewer narcotics, and reported better hip function. No statistical differences in complication rates were detected between AA and PA. Ultimately, the choice of surgical approach in primary THA should consider preference and experience of the surgeon as well as preference and anatomy of the patient.

The learning curve for the direct anterior approach for total hip arthroplasty: a single surgeon's first 500 cases

BACKGROUND

Concerns arise over the early complications encountered during the learning curve for the direct anterior approach for total hip arthroplasty.The purpose of this study is to examine the learning experience of a single surgeon in adapting this approach.

METHODS

The 1st 500 primary total hip arthroplasties are reviewed. The patients were evaluated out to 3 months. Rates of major complications, reoperations, periprosthetic fractures, heterotopic ossification, leg length discrepancies and lateral femoral cutaneous nerve deficits were identified for each of 100 patients.

RESULTS

The major complication rate decreased from 5% to 2% throughout the series. Reoperation rates fluctuated from 2% in the 1st 100 cases to 3% in the 4th 100 cases to 1% in the 5th 100 cases. The periprosthetic fracture rate decreased from 9% to 2%.

CONCLUSIONS

The incidence of heterotopic ossification declines throughout the series and is attributed to changes in irrigation technique and quantity. The incidence of major complications decreases with increasing experience. The most dramatic improvements occur after the 1st group of 100 cases.

Heterotopic Ossification Prophylaxis After Total Hip Arthroplasty: Randomized Trial of 400 vs 700 cGy

BACKGROUND

Heterotopic ossification (HO) is a known complication following total hip arthroplasty. Radiation is an effective prophylaxis, but an optimal protocol has yet to be determined. We performed a randomized, double-blinded clinical trial in high-risk patients to determine the efficacy of 400 vs 700 cGy doses of radiation.

METHODS

One hundred forty-seven patients undergoing total hip arthroplasty and at high risk for HO at an urban medical center were randomized to receive either a single 400 or 700 cGy dose of radiation postoperatively. High risk was defined as a diagnosis of diffuse idiopathic skeletal hyperostosis, hypertrophic osteoarthritis, ankylosing spondylitis, or history of previous HO. Radiation was administered on the first or second postoperative day. A single blinded reviewer graded radiographs taken immediately postoperatively and at a minimum of 6 months postoperatively using the Brooker classification. Progression was defined as an increase in Brooker classification. Operative data including surgical approach, implant fixation, revision surgery, and postoperative range of motion data were also collected.

RESULTS

A significantly greater portion of patients who received the 400 cGy dose demonstrated progression of HO than patients who received the 700 cGy dose. There were no wound complications. No preoperative factors were associated with a higher rate of progression. Patients who progressed had less flexion on physical examination than patients who did not progress, but this was not clinically significant.

CONCLUSION

Seven hundred centigray was superior to 400 cGy in preventing HO formation following total hip arthroplasty in high-risk patients and may be the more effective treatment in this population. Further studies comparing 700 cGy to dosages between 400 and 700 cGy may help to clarify if a more optimal dose can be identified.

Influence of surgical approach on heterotopic ossification after total hip arthroplasty - is minimal invasive better? A case control study

BACKGROUND

Heterotopic ossification (HO) is a well-known complication after total hip arthroplasty (THA). Recently, the trend is to operate THA minimally invasive being less traumatic than standard approaches and promising a faster return to activity. The purpose of the study was to investigate if minimal invasive surgery (MIS), leads also to less HO after THA.

METHODS

This retrospective study included 134 consecutive patients undergoing THA. In 42 (31.3%) patients a standard modified anterolateral (STD-Watson-Jones), in 28 (20.9%) patients a standard transgluteal Bauer approach (STD-Bauer), in 39 (29.1%) a MIS direct anterior approach (AMIS) and in 25 (18.7%) patients a MIS anterolateral (MIS-AL) approach was used. Standard preoperative anterior-posterior and lateral radiographs were assessed for occurrence of HO. HO was classified according to Brooker. In addition, short- and long-term adverse events were noted. Data was statistically analyzed using Chi-square tests, analysis of variance, multivariate data analysis and Pearson's correlation (p < 0.05).

RESULTS

Overall, HO was found in 38 caucasian patients (28.4%) after THA. The STD-Watson-Jones group showed the highest HO rate (45.2% n = 19) with a significant difference to the AMIS (23.1% n = 9) and STD-Bauer approach (14.3% n = 4). No statistical difference was found to the MIS-AL approach (24.0% n = 6). Postoperative complications did not differ significantly except for a higher incidence of Trendelenburg`s sign in STD-Bauer.

CONCLUSIONS

The rate and degree of HO after THA were significantly different with regards to the surgical approach. The standard modified anterolateral approach resulted in the highest HO rate, however, MIS approaches showed higher HO rates than the STD-Bauer.

Direct Anterior Approach: Risk Factor for Early Femoral Failure of Cementless Total Hip Arthroplasty: A Multicenter Study

BACKGROUND

The direct anterior approach for total hip arthroplasty (THA) is marketed with claims of superiority over other approaches. Femoral exposure can be technically challenging and potentially lead to early failure. We examined whether surgical approach is associated with early THA failure.

METHODS

A retrospective review of 478 consecutive early revision THAs performed within 5 years after the primary THAs at 3 academic centers from 2011 through 2014 was carried out. Exclusion criteria resulted in a final analysis sample of 342 early-failure THAs. The surgical approach of the primary operation that was revised, the time to the revision, and the etiology of the failure leading to the revision were documented.

RESULTS

Analysis of the revisions due to early femoral failure showed them to be more common in patients who had undergone the direct anterior approach (57/112; 50.9%) than in those treated with the direct lateral (39/112; 34.8%) or the posterior (16/112; 14.3%) approach (p = 0.001). In multivariate regression analysis controlling for age, sex, laterality, Dorr bone type, body mass index (BMI) at revision, bilateral procedure (yes/no), and femoral stem type, the direct anterior approach remained a significant predictor of early femoral failure (p = 0.007). The majority of early revisions due to instability were associated with the posterior (19/40; 47.5%) or direct anterior (15/40; 37.5%) approach (p = 0.001 for the comparison with the direct lateral approach [6/40; 15.0%]).

CONCLUSIONS

Despite claims of earlier recovery and improved outcomes with the direct anterior approach for THA, our findings indicate that that approach may confer a greater risk of early femoral failure and, along with the posterior approach, confer a greater risk of early instability compared with the direct lateral approach.

LEVEL OF EVIDENCE

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

Total hip arthroplasty via the anterior approach: tips and tricks for primary and revision surgery

PURPOSE

Described for the first time in the 1950s, the direct anterior approach to the hip has been gaining in popularity over the last decade following the trend of minimally invasive surgery. This paper provides an overview of the approach and its indications and various uses and focuses on its utility in the revision setting. A detailed overview of the technique including tips and tricks as well as an explanation of common errors are included.

METHOD

Graphic and clinical study of the approach, indications and feasibility.

RESULTS

The reported benefits of the direct anterior technique include enhanced post-operative recovery and respect for all the innervation and vascularization territories. It has been shown to be safe and effective in revision settings, to decrease the occurrence of heterotopic ossification, to enhance the accuracy of acetabular cup positioning, and to improve post-operative rehabilitation while having comparable outcomes in terms of loosening or component failure. Additionally, thromboembolic events have been shown to be decreased compared to other approaches. The most common reported complications in the revision setting is intra-operative fracture. The decision of a surgeon to transition to this approach, however, comes with a learning curve and potentially detrimental complications if done improperly.

DISCUSSION

In addition to its appeal in the primary setting, the approach could possibly be a solution to decrease the morbidity associated with revision surgery through its use of a fresh tissue plane not previously traumatized with the primary approach.