Incidence Of Heterotopic Ossification Research Articles

Heterotopic Ossification After Elbow Fractures.

Heterotopic ossification (HO), a complication after surgical repair of elbow fractures, can result in pain, decreased range of motion, or complete ankylosis of the joint. This updated systematic review focused on compiling incidence and prevalence rates of HO after surgical repair of various types of elbow fractures. The overall incidence of HO after surgical repair was calculated to be 28.7%, a result comparable with rates in the literature. Further analysis suggested that the odds of having HO may be less after distal humerus fractures than after proximal radius fractures, terrible triad injuries, and elbow fractures/dislocations. [Orthopedics. 2021;44(1):10-16.].

Heterotopic Ossification Following Total Ankle Arthroplasty With Fourth-Generation Prostheses.

The purpose of the present study was to assess the radiographic incidence, location, and classification of heterotopic ossification (HO) in patients who underwent total ankle arthroplasty (TAA) with a 4th generation prostheses at a minimum of 1-year follow up. Baseline demographic, radiographic, and operative factors between patents with and without HO were compared. Ninety ankles that underwent TAA with a 4th generation protheses, INFINITY (n = 62) or CADENCE (n = 28) were followed for an average of 23.7 (range, 12-49) months. Incidence and location of HO was assessed on weightbearing radiographs, and severity graded according to the modified Brooker classification. Data was compared between patents with and without HO to identity any predisposing factors. In 90 ankles that underwent 4th generation TAA, HO incidence was 55.6% (n = 50); 56.5% (n = 35) for INFINITY, and 53.6% (n = 15) for CADENCE. Twenty-five cases of HO were observed posteriorly, 16 anteriorly, and 9 combined. Severity was as follows; class I in 19 cases (38%), class II in 20 (40%), class III in 9 (18%) and class IV in 2 (4%). A single ankle required a non-revisional reoperation for HO debridement; reoperation rate of 2%. The present study suggests a similarly high incidence of HO after TAA with two different 4th generation protheses (INFINITY 56.5%, CADENCE 53.6%). A trend for differences in location and severity between the protheses may also be present. Given the paucity of literature, additional studies with longer follow-up are warranted to discern the significance of HO following TAA with 4th generation protheses. Level III: Retrospective cohort study.

The Impact of Smoking on Radiological Outcomes in Patients After Total Arthroplasty of the Cervical Intervertebral Discs

Objective: to investigate the impact of smoking on radiological outcomes in patients after one- and two-level total arthroplasty ( ТА ) of the cervical intervertebral discs. Material and methods . A single-center retrospective observational cohort study was performed. The study included 127 medical records of patients who had undergone one- or two-level TA of the cervical intervertebral discs for their degenerative disease. The medical records were divided into two groups: 32 smokers and 95 nonsmokers. Results. No statistically significant differences were found in the values of cervical lordosis and the movement amplitude of the operated segments in the postoperative period. Comparing the values of the movement amplitude of the operated segments in the group of smoking patients demonstrated significant pre- and postoperative differences in the values of the above radiological parameter (p = 0.017). Comparing the rates of loss of segmental motion of the operated segments and the incidence of heterotopic ossification did not reveal any significant differences. Analysis of Kaplan-Meier curves showed no statistically significant differences between the types of implants used in smoking patients. Conclusion. Smoking has no statistically significant impact on radiological outcomes in patients after one- or two-level ТА of the cervical intervertebral discs.

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

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. 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. 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. 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.

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

AimsDystrophic 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.MethodsWe 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.ResultsOur 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.ConclusionTaken 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.

Clinical and radiological outcomes of single-level cervical disc arthroplasty in the patients with preoperative reversible kyphosis: A matched cohort study

ObjectiveThe performance of cervical disc arthroplasty (CDA) in the spine with malalignment was unclear. The purpose of the study was to report the clinical and radiological outcomes of single-level CDA in the patients with preoperative reversible kyphosis (RK) and compare these results with a matched cohort of preoperative lordosis. Patients and MethodsFrom 2014 to 2018, 36 patients with preoperative RK were matched with 229 patients with preoperative lordosis. The Japanese Orthopedic Association score, Neck Disability Index, Visual Analog Scale were used to evaluate clinical outcomes. Radiological evaluations included range of motion (ROM), C2−7 Cobb angle, shell angle (SA) at surgical level, functional spinal unit (FSU) angle and heterotopic ossification (HO). ResultsThe mean follow-up was 40.1 months. Both groups achieved significant improvements in clinical outcomes without significant intergroup differences. Before surgery, lordosis group had significantly greater C2−7 angle (9.5° vs -8.4°), SA (1.6° vs -3.7°), and FSU (2.9° vs -3.7°). After surgery, RK group experienced significant improvements in C2−7 angle and SA compared with preoperative data. In lordosis group, C2−7 angle, SA, and FSU were maintained. At the last follow-up, the intergroup difference of C2−7 angle, SA, and FSU remained significant. ROMs were preserved in both groups. The ROM of RK group was slightly lower than that of lordosis group but failing to reach a significance. Eleven patients in lordosis group and 21 patients in RK group developed HO (P = 0.127). There was a significant greater incidence of high-grade HO (grade Ⅲ, Ⅳ) in RK group (33.3 % vs 11.1 %, P = 0.034). ConclusionBoth groups achieved satisfactory and comparable clinical outcomes after CDA. Despite the remarkable improvements compared with preoperative values, the cervical alignment of RK group was still significantly inferior to that of lordosis group. More HO formation occurred in RK group. Based on these results, we did not recommend CDA to the patients with preoperative RK.

Implant complications after one-level or two-level cervical disc arthroplasty: A retrospective single-centre study of 105 patients.

The aim of study was to investigate the complications of cervical disc arthroplasty (CDA) and to discuss the factors affecting the mobility of the prosthesis and the measures to prevent these complications. Hundred and five patients who underwent CDA between 2009 and 2016 were enrolled. The clinical and radiographic outcomes were used to assess and the complications were recorded as well.All the patients were followed-up with an average of 41.30 ± 16.90 months with an average age of 47.90 ± 9.22 years. The visual analogue scale (VAS), neck disability index (NDI), and Japanese Orthopaedic Association (JOA) scores improved significantly at the final follow-up (FU) compared with the preoperative values. At the final FU, the overall incidence of heterotopic ossification (HO) was 51.42%. The distribution of different grades of HO was low-level HO (53.7%) and high-level HO (46.3%). No significant differences were found in the NDI, VAS, or JOA scores between patients with HO and those without HO (P > .05). In the high-level HO patients, the range of mobility (ROM) was significantly reduced compared with the low-level HO patients and those without HO (P < .05). The anterior displacement, subsidence, and instability were observed in 1 patient respectively and the segmental kyphosis, adjacent segment degeneration in 3 patients respectively. The patient of CDA instability also suffered severe neck pain and the revision surgery was performed.Postoperative complications in CDA such as HO, segmental kyphosis, and prosthesis displacement are prone to occur, affecting prosthesis mobility. Surgical indications should be strictly controlled, and intraoperative and postoperative treatments should be given great attention in order to reduce prosthesis-related complications.

250. Occurrence and clinical implications of heterotopic ossification after cervical disc arthroplasty with Prestige LP™ disc at two contiguous levels

BACKGROUND CONTEXT Evaluation of 10-year clinical safety and effectiveness of cervical disc arthroplasty (CDA) using the Prestige LP™ disc to treat degenerative cervical spine disease at two adjacent levels has been completed. Occurrence of heterotopic ossification (HO) surrounding the prosthesis following CDA has been reported for other prostheses and found to limit the range of motion and to negatively impact function of the prosthesis. PURPOSE To assess the impact of HO on clinical outcomes and angular range of motion (ROM) after CDA with the Prestige LP™ disc at two levels. STUDY DESIGN/SETTING Multicenter, prospective, randomized, controlled, FDA-approved clinical trial. PATIENT SAMPLE A total of 209 subjects implanted with Prestige LP™ discs at two cervical levels in the clinical trial and participating in a post-approval study. The 10-year follow-up rate was 86% after excluding subjects at sites not participating in the PAS study, deaths, and withdrawals. OUTCOME MEASURES HO assessed on lateral neutral radiographs and graded 0-IV; clinical outcomes of overall success, neurological success, neck disability index (NDI), neck pain, arm pain and SF-36 Physical Component Summary (PCS) score; ROM; implant-related adverse event (AE) rate. METHODS Data were obtained as part of an FDA-approved clinical trial and a separate subgroup analysis was performed for this study. ROM was compared by HO grade, and clinical outcomes were compared between HO subgroups (Grade 0-II vs III/IV) based on HO severity at 2 and 10 years after surgery. RESULTS The Grade III/IV HO incidence at either or both index levels was 24.2% (48/198) at 2 years and 39.0% (57/146) at 10 years. No statistical difference was found in overall success, neurological success, NDI, neck pain, arm pain, or SF-36 PCS scores between the HO subgroups (Grade 0-II vs III/IV) at either 2 or 10 years. The cumulative rate of possible implant-related AEs was higher in subjects having Grade III/IV HO than those having Grade 0-II HO at 2 years (56.3% vs 24.4%) and 10 years (47.8% vs 17.9%), specifically in two subcategories: spinal events and heterotopic ossifications reported by the investigators. However, no statistical difference was found between HO subgroups in possible implant-related serious AEs or secondary surgeries at index or adjacent levels. The average angular ROMs at index levels were lower in subjects with higher-grade HO at 2 and 10 years. The average ROMs at the superior level were 8.8°, 6.6°, 3.2°, and 0.3°, respectively for HO Grade 0-I, II, III and IV groups at 10 years, and 7.9°, 6.2°, 3.7°, and 0.6°, respectively, at the inferior level. CONCLUSIONS Radiographically severe (Grade III or IV) HO after CDA with the Prestige LP disc at two levels did not significantly affect efficacy or safety (severe AEs or secondary surgeries) outcomes. However, severe HO, particularly Grade IV HO, significantly limited ROM, as expected. FDA DEVICE/DRUG STATUS Prestige LP™ Disc, Approved for 2-level cervical disc arthroplasty in 2016 (Approved for this indication)

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

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

Incidence of Heterotopic Ossification in Direct Anterior Approach to Total Hip Arthroplasty with use of Aspirin as Thromboembolic Prophylaxis

CONTEXTHeterotopic ossification (H.O.) is a common occurrence after total hip arthroplasty (THA) with significant potential clinical ramifications. Controversy still exists regarding the exact etiology of the disorder, including possible risk factors. Surgical technique, surgical approach, postoperative medication protocols and even thromboembolic prophylaxis have been implicated in the formation of H.O. Our study looked at one institution with a single surgeon performing direct anterior THA (DAA THA) in patients who received aspirin (ASA) as monotherapy for thromboembolic prophylaxis.METHODSPatients at a single institution who underwent DAA THA between 2015 and 2019 were identified by CPT code. 45 patients ultimately met inclusion criteria. Postoperative radiographs were analyzed retrospectively for H.O. according to the Brooker classification. Several patient characteristics and comorbidities were statistically analyzed using Chi-square tests, Fisher Exact tests, Wilcox rank sum tests, and Pearson correlation.RESULTS12 patients (26.7%) were found to have heterotopic ossification (67% Class 1, 8% Class 2, 25% Class 3, and 0% Class 4); with a median follow up of 35 weeks (range: 12-96). 25% of these patients received ASA 325mg BID while 75% received ASA 81 BID. No statistical differences in development of H.O. were detected among age, gender, BMI, sex, race, diabetes, or NSAID use in the post-operative interval. There were significantly more smokers in the H.O. group (50% vs. 9%, p<0.006).CONCLUSIONSOur analysis aimed to quantify the incidence of H.O. with consistency in surgical approach and post-operative protocol. There have been few studies on this topic, and we believe it is very relevant with the increasing use of aspirin in the post-operative protocol for thromboembolic prophylaxis. Our retrospective analysis identified H.O. at rates similar to previous studies in DAA.

Prophylactic treatment of rapamycin ameliorates naturally developing and episode -induced heterotopic ossification in mice expressing human mutant ACVR1

BackgroundFibrodysplasia ossificans progressiva (FOP) is a rare autosomal-dominant disease characterized by heterotopic ossification (HO) in soft tissues and caused by a mutation of the ACVR1A/ALK2 gene. Activin-A is a key molecule for initiating the process of HO via the activation of mTOR, while rapamycin, an mTOR inhibitor, effectively inhibits the Activin-A-induced HO. However, few reports have verified the effect of rapamycin on FOP in clinical perspectives.MethodsWe investigated the effect of rapamycin for different clinical situations by using mice conditionally expressing human mutant ACVR1A/ALK2 gene. We also compared the effect of rapamycin between early and episode-initiated treatments for each situation.ResultsContinuous, episode-independent administration of rapamycin reduced the incidence and severity of HO in the natural course of FOP mice. Pinch-injury induced HO not only at the injured sites, but also in the contralateral limbs and provoked a prolonged production of Activin-A in inflammatory cells. Although both early and injury-initiated treatment of rapamycin suppressed HO in the injured sites, the former was more effective at preventing HO in the contralateral limbs. Rapamycin was also effective at reducing the volume of recurrent HO after the surgical resection of injury-induced HO, for which the early treatment was more effective.ConclusionOur study suggested that prophylactic treatment will be a choice of method for the clinical application of rapamycin for FOP.

Incidence of bone loss after Prestige-LP cervical disc arthroplasty: a single-center retrospective study of 396 cases

BACKGROUND CONTEXTThe development of bone loss (BL) at the operated level after cervical disc arthroplasty (CDA) has not been well recognized. The incidence of BL may be correlated with the prosthesis type. Currently, no study has reported the incidence of BL after CDA with the Prestige-LP disc, and this remains an active area of research. PURPOSETo determine the incidence of BL after Prestige-LP CDA and evaluate the impact of BL on clinical and radiological outcomes. STUDY DESIGNThis is an observational study. PATIENT SAMPLEA total of 396 patients were reviewed. OUTCOME MEASURESThe Japanese Orthopedics Association (JOA), Visual Analogue Scale (VAS), and Neck Disability Index (NDI) scores were evaluated. Cervical lordosis, disc angle, global and segmental range of motion (ROM), heterotopic ossification (HO), and BL were measured. METHODSWe retrospectively reviewed patients who underwent Prestige-LP disc from January 2008 to October 2018 at our institution. Clinical outcomes were evaluated using JOA, VAS, and NDI scores. Radiological variables, including cervical lordosis, disc angle, global and segmental ROM, HO, and BL, were retrieved. RESULTSA total of 396 patients and 483 CDAs were evaluated. BL occurred in 56.6% of patients and 52.8% of CDA segments. Mild BL occurred in 30.2%, moderate BL in 37.3%, and severe BL in 32.5% of CDA segments. Notably, 88.2% of CDA segments developed BL within the first 3 months, and 19.1% of them progressed at 6 months. However, no progressive BL after 12 months was seen. About 50.2% of CDAs showed superior and inferior endplates involvement. The incidence of BL was associated with age, surgery type, level distribution, and incidence and grade of HO. Patients with BL had a better segmental ROM, but no relationships between patients with or without BL were found in clinical outcomes. CONCLUSIONSBL was a common but self-limited phenomenon after CDA at the early postoperative stage. It occurred more often in relatively young age patients, two-level CDA, and C5/6 segment. However, patients suffering from BL showed no deterioration of the clinical outcomes, more exceptional motion preservation at the arthroplasty level, and lower incidence with a lower grade of HO.

Serum uric acid level is associated with the incidence of heterotopic ossification following elbow trauma surgery

Heterotopic ossification (HO) is a common complication after surgery for elbow trauma. Uric acid is the end product of purine metabolism and has several physiological and pathogenic roles. However, the relationship between HO and uric acid has not been explored. This retrospective study aimed to assess the relationship between HO and serum uric acid (SUA). We retrospectively reviewed data from 155 patients undergoing elbow trauma surgery in our hospital between January 2013 and December 2018. One hundred patients were included according to the inclusion criteria. They were divided into 2 groups according to the presence or absence of HO, and the SUA level was compared between groups using the independent samples t test. The optimal prognostic cutoff value was obtained using the maximum value of the Youden index. The SUA level was significantly higher in the HO group than in the non-HO group (362.0 ± 87.4 μmol/L vs. 318.3 ± 87.0 μmol/L; P < .05). Using the maximum value of Youden index, 317.5 μmol/L was determined to be the optimal SUA cutoff value for the prediction of HO, with a sensitivity of 68.75% (95% confidence interval [CI], 54.67%-80.05%) and specificity of 55.77% (95%CI,42.34%-68.40%). Our study was the first to find that the high SUA level is a risk factor for HO of the elbow joint after trauma. Moreover, 317.5 μmol/L is the SUA threshold predicting the occurrence and development of HO of the elbow, with high sensitivity and specificity.

Risk Factors for the Development of Heterotopic Ossification in Operatively Treated Terrible Triad Injuries

Heterotopic ossification (HO) formation after complex elbow injuries can significantly impact function. Prior studies report a 2-56% incidence of HO following elbow trauma however these findings represent a heterogenous cohort of fracture patterns. The purpose of our study was to evaluate the prevalence of HO in patients with isolated terrible triad injuries and identify risk factors associated with the formation of HO. We hypothesized that prolonged dislocation, multiple reduction attempts, and delay in definitive surgical stabilization are associated with more significant radiographic and functionally limiting HO.

Occurrence and clinical implications of heterotopic ossification after cervical disc arthroplasty with the Prestige LP Cervical Disc at 2 contiguous levels.

The authors sought to assess the impact of heterotopic ossification (HO) on clinical outcomes and angular range of motion (ROM) after cervical disc arthroplasty (CDA) performed with the Prestige LP Cervical Disc (Prestige LP disc) at 2 levels. HO was assessed and graded from 0 to IV for increasing severity on lateral neutral radiographs at each visit in 209 patients who underwent implantation of Prestige LP discs at 2 cervical levels in a clinical trial with extended 10-year follow-up. ROM was compared by using HO grade, and clinical outcomes were compared between HO subgroups (grade 0-II vs III/IV) based on HO severity at 2 and 10 years after surgery. The grade III/IV HO incidence at either or both index levels was 24.2% (48/198) at 2 years and 39.0% (57/146) at 10 years. No statistical difference was found in overall success; neurological success; or Neck Disability Index (NDI), neck pain, arm pain, or SF-36 Physical Component Summary (PCS) scores between the HO subgroups (grade 0-II vs III/IV) at either 2 or 10 years. The cumulative rate of possible implant-related adverse events (AEs) was higher in patients having grade III/IV HO at 2 years (56.3%) and 10 years (47.8%) compared with those having grade 0-II HO at 2 years (24.4%) and 10 years (17.9%), specifically in 2 subcategories: spinal events and HOs reported by the investigators. No statistical difference was found between the HO subgroups in possible implant-related serious AEs or secondary surgeries at the index or adjacent levels. The average angular ROMs at index levels were lower in subjects with higher-grade HO at 2 and 10 years. The average ROMs at the superior level were 8.8°, 6.6°, 3.2°, and 0.3°, respectively, for the HO grade 0/I, II, III, and IV groups at 10 years, and 7.9°, 6.2°, 3.7°, and 0.6°, respectively, at the inferior level. Radiographically severe (grade III or IV) HO after CDA with the Prestige LP disc at 2 levels did not significantly affect efficacy or safety outcomes (severe AEs or secondary surgeries). However, severe HO, particularly grade IV HO, significantly limited ROM, as expected.

The Effect of Footprint Mismatch on Heterotopic Ossification After Cervical Disk Replacement.

This was a retrospective study. The objective of this study was to analyze risk factors of heterotopic ossification (HO) after cervical disk replacement (CDR) and evaluate the effect of footprint mismatch on HO. Incidence of HO after CDR is high, but the exact related factors have not been fully elucidated. Radiographic data of patients who had undergone CDR with Prestige LP or Discover prosthesis in Tongji Hospital from July 2012 to December 2015 were reviewed. HO was graded according to McAfee classification and classified according to Jin morphologic classification. Footprint matching degree was evaluated using 3-dimensional computed tomographic images. Cervical sagittal alignment, functional spinal unit height, and range of motion were measured on radiographs. Preexisting degeneration was scored using Walraevens scoring system. Postulated risk factors including general factors, cervical sagittal alignment, functional spinal unit height, range of motion, postoperative biomechanical changes, preexisting degeneration, number of surgical levels, prosthesis type, use of nonsteroid anti-inflammatory drugs, and footprint matching degree were analyzed by first univariate tests, and then multivariate logistic regression was done to examine the relation with HO occurrence. Effect of footprint mismatch on type 1 HO of morphologic classification was evaluated. Data of 46 patients were collected; 43 were finally evaluated with a total 57 prostheses implanted, with a mean follow-up duration of 41.16±12.49 months. No significant differences in basic characteristics existed between 2 prosthesis groups, except follow-up time. Incidence of HO was 66.7%. Mean footprint matching degree in sagittal plane was 0.877±0.068 and in coronal plane was 0.852±0.092. Mean overall footprint matching degree was 0.699±0.102 (range: 0.388-0.993). Prosthesis type and footprint matching degree were significantly related with HO among all postulated risk factors in both univariate and multivariate analyses (P<0.05); the latter had larger Exp(B). Type 1 HO occurrence significantly related with footprint mismatch. Incidence of HO after CDR was high, and serious footprint mismatch existed. HO occurrence was significantly related with prosthesis type and footprint matching degree; the latter played a more important role.

Impact of heterotopic ossification after single-level cervical disc replacement on adjacent segment

Objective: To investigate the impact of heterotopic ossification (HO) after cervical disc replacement (CDR) on clinical outcome and radiological outcome of adjacent segment. Methods: The data of patients underwent single-level Prestige-LP CDR between January 2008 and March 2014 in West China Hospital with a minimum 36 months of follow-up were retrospectively analyzed in this study. The incidence of HO, whether it affected clinical outcome, and its impact on adjacent segment intervertebral disc height (IDH), range of motion (ROM) and adjacent segment degeneration were observed. The data were compared with independent sample t test between the two groups. Results: Ninety-two patients were included in this study, including 48 males and 44 females, the mean age was (44±8) years, and the mean follow-up was (62±23) months. At the final follow-up, 34 patients developed HO after CDR, but the incidence of Grade 4 HO was 7.6%. In both of the HO and non-HO groups, clinical outcomes at the final follow-up were all significantly improved when compared to those before the operation. And there was no significant differences in any clinical indexes between the HO and non-HO groups. The adjacent segment IDH before operation and at the final follow-up in the HO group and non-HO group were similar(t=0.596, 0.825 and t=0.877, 0.644, all P>0.05). The preoperative adjacent segment ROM of HO group was similar with that in non-HO group(t=0.056, 0.709, both P>0.05), but the adjacent segment ROM in HO group was higher than that in the non-HO group at the final follow-up (upper adjacent segment: 10.0°±2.0° vs 9.0°±1.3°; lower adjacent segment: 10.2°±1.9° vs 8.8°±1.3°, t=2.824, 4.022, both P<0.05). The incidence of adjacent segment degeneration of HO group was higher than that of non-HO group at the final follow-up(41.2% vs 19.0%, χ(2)=5.343, P<0.05). Conclusions: HO is a common phenomenon in the long-term follow-up after the CDR operation with Prestige LP prosthesis, but HO does not affect the improvement of clinical outcome. HO after CDR might be one of important risk factors accelerating adjacent segment degeneration.

Herbert screwing directly via the anterior approach for femoral head fractures of Pipkin type II in the youth

Objective To evaluate Herbert screwing directly via the anterior approach for femoral head fractures of Pipkin type Ⅱ in the youth. Methods A retrospective analysis was conducted of the 16 patients who had been treated at Department of Orthopaedics, Union Hospital, Tongji Medical College for femoral head fractures of Pipkin type Ⅱ from August 2016 to June 2018. They were 9 men and 7 women, aged from 18 to 45 years (mean, 25.6 years). Of them, 10 cases who had been complicated with posterior dis-location of the hip received emergency hip reduction(<6 h) before surgical fixation. All the patients underwent Herbert screwing directly via the anterior approach. Their incision length, operation time, intraoperative blood loss, hospitalization time, Harris hip scores, therapeutic efficacy and complications were recorded. Results In this series, the incision length averaged 10.4 cm, operation time 45.6 min, intraoperative blood loss 46.5 mL, and hospitalization time 4.0 d. All the 16 patients were followed up for 11 to 15 months (average, 12.7 months). Their Harris hip scores at preoperation, 3, 6 and 9 months postoperation and at the last follow-up were, respectively, 14.3±2.2, 64.8±2.4, 81.1±4.9, 88.1±4.6 and 91.9±3.4 points, showing a significant difference between any 2 time points (P<0.05). The therapeutic efficacy at the last follow-up by the Thompson-Epstein clinical evaluation was assessed as excellent in 9 cases, as good in 6 and as fair in one. No osteonecrosis of the femoral head or heterotopic ossification was observed by follow-up. Conclusion For young patients with femoral head fracture of Pipkin type Ⅱ, Herbert screwing directly via the anterior approach provides easy exposure and manipulation, does not aggravate the blood supply to the femoral head, decreases incidence of heterotopic ossification, and leads to shorter operation time and quick functional recovery of the hip. Key words: Femoral head fractures; Fracture fixation, internal; Surgical procedures, minimally invasive; Surgical approach

Traumatic brain injury enhances the formation of heterotopic ossification around the hip: an animal model study.

The incidence of heterotopic ossification (HO) is at its highest when trauma of the hip or pelvis concurs with traumatic brain injury (TBI). The pathogenic mechanisms underlying the neurogenic enhancement of the formation of HO remain, however, poorly understood. Hence, the goal of the present study was to develop a novel small animal model that combines hip and brain trauma that can prove the enhancement of HO around the hip after TBI. Forty male Wistar rats were divided into four groups, to undergo hip surgery alone (group 1), hip surgery + moderate TBI (group 2), hip surgery + severe TBI (group 3) and only severe TBI (group 4). The femoral canal was reamed up to 2mm and a muscle lesion was made to simulate hip surgery. An established controlled cortical impact model was used to create a TBI. Twelve weeks after surgery, the hip with the proximal half of the femur and the pelvic bone was removed and subjected to micro-computed tomography (µCT) analysis. A quantitative analysis using a modified Brooker score as well as a quantitative analysis using a bone-to-tissue ratio was used. No HO could be found in all the ten animals that did not undergo hip surgery (group 4). In the animals that did undergo surgery to the hip, no HO was found in only one animal (group 1). All the other animals developed HO. In this study, significantly more HO was found in animals that underwent an additional severe TBI. The newly developed rat model, with a combined hip and brain trauma, showed an enhancement of the HO formation around the hip after severe TBI.

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

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. 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. 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. 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 III, retrospective, comparative case-control study.