Surgical site soft tissue thickness as a predictor of complications following arthroplasty

Appreciation of soft-tissue thickness(STT)at surgical sites is an increasingly recognized aspect of arthroplasty procedures as it may potentially impacting postoperative outcomes.Recent research has focused on the predictive value of preoperative STT measurements for complications following various forms of arthroplasty,particularly infections,across procedures such as total knee,hip,shoulder,and ankle replacements.Several studies have indicated that increased STT is associated with a higher risk of complications,including infection and wound healing issues.The assessment of STT before surgery could play a crucial role in identifying patients at a higher risk of complications and may be instru-mental in guiding preoperative planning to optimize outcomes in arthroplasty procedures.Standardized measurement techniques and further research are essential to enhance the reliability and clinical utility of STT assessment for arthro-plasty surgery.

Machine learning identifies the risk of complications after laparoscopic radical gastrectomy for gastric cancer

BACKGROUND Laparoscopic radical gastrectomy is widely used,and perioperative complications have become a highly concerned issue.AIM To develop a predictive model for complications in laparoscopic radical gastrectomy for gastric cancer to better predict the likelihood of complications in gastric cancer patients within 30 days after surgery,guide perioperative treatment strategies for gastric cancer patients,and prevent serious complications.METHODS In total,998 patients who underwent laparoscopic radical gastrectomy for gastric cancer at 16 Chinese medical centers were included in the training group for the complication model,and 398 patients were included in the validation group.The clinicopathological data and 30-d postoperative complications of gastric cancer patients were collected.Three machine learning methods,lasso regression,random forest,and artificial neural networks,were used to construct postoperative complication prediction models for laparoscopic distal gastrectomy and laparoscopic total gastrectomy,and their prediction efficacy and accuracy were evaluated.RESULTS The constructed complication model,particularly the random forest model,could better predict serious complications in gastric cancer patients undergoing laparoscopic radical gastrectomy.It exhibited stable performance in external validation and is worthy of further promotion in more centers.CONCLUSION Using the risk factors identified in multicenter datasets,highly sensitive risk prediction models for complications following laparoscopic radical gastrectomy were established.We hope to facilitate the diagnosis and treatment of preoperative and postoperative decision-making by using these models.

Insights into complications after unicompartmental knee arthroplasty

Zhao's study,offers a comprehensive analysis of unicompartmental knee arthroplasty(UKA)revision indications.The study provides a detailed,case-by-case analysis of the factors leading to knee revision surgery in 13 patients.Not only elucidates the complexities of UKA revisions but also underscores the importance of continuous improvement in surgical techniques and the adoption of innovative technologies.

Possible Risk Factors for Severe Complications Occurring after Primary Total Knee Arthroplasty

Objective Total knee arthroplasty is one of the most common orthopedic surgeries.Readmission due to severe complications after total knee arthroplasty is a grave concern to surgeons.In this study,we evaluated the risk factors for severe complications after primary total knee arthroplasty.Methods We retrospectively collected clinical data of 2,974 patients who underwent primary total knee arthroplasty from July 2013 to June 2019 in our hospital.Postoperative complication≥gradeⅢwas defined as severe complication according to Clavien-Dindo classification system.Binary logistic regression was used to identify the predictive risk factors for severe complications.Results The complication rate after primary total knee arthroplasty was 6.8%and severe complication rate was 2.5%.Male(OR=2.178,95%CI:1.324-3.585,P=0.002),individuals above 75 years old(OR=1.936,95%CI:1.155-3.244,P=0.012),arrhythmia(OR=2.913,95%CI:1.350-6.285,P=0.006)and cerebrovascular disease(OR=2.804,95%CI:1.432-5.489,P=0.003)were predictive risk factors for severe complications after primary total knee arthroplasty.Conclusion Advanced age,male,arrhythmia,and cerebrovascular disease might be patients-related risk factors for postoperative severe complications after primary total knee arthroplasty.Special attention should be paid to patients with risk factors.

Nomogram to predict postoperative complications in elderly with total hip replacement

BACKGROUND By analyzing the risk factors of postoperative complications in elderly patients with hip replacement,We aimed to develop a nomogram model based on preoperative and intraoperative variables and verified the sensitivity and specificity for risk stratification of postoperative complications in elderly with total hip replacement patients.AIM To develop a nomogram model for risk stratification of postoperative complications in elderly with total hip replacement patients.METHODS A total of 414 elderly patients who underwent surgical treatment for total hip replacement hospitalized at the Affiliated Hospital of Guangdong Medical University from March 1,2017 to August 31,2019 were included into this study.Univariate and multivariate logistic regression were conducted to identify independent risk factors of postoperative complication in the 414 patients.A nomogram was developed by R software and validated to predict the risk of postoperative complications.RESULTS Multivariate logistic regression analysis revealed that age(OR=1.05,95%CI:1.00-1.09),renal failure(OR=0.90,95%CI:0.83-0.97),Type 2 diabetes(OR=1.05,95%CI:1.00-1.09),albumin(ALB)(OR=0.91,95%CI:0.83-0.99)were independent risk factors of postoperative complication in elderly patients with hip replacement(P<0.05).For validation of the nomogram,receive operating characteristic curve revealed that the model predicting postoperative complication in elderly patients with hipreplacement was the area under the curve of 0.8254 (95%CI: 0.78-0.87), the slope of the calibrationplot was close to 1 and the model passed Hosmer-Lemeshow goodness of fit test (χ^(2) = 10.16, P =0.4264), calibration in R E_(max) = 0.176, E_(avg) = 0.027, which all demonstrated that the model was ofgood accuracy.CONCLUSIONThe nomogram predicting postoperative complications in patients with total hip replacementconstructed based on age, type 2 diabetes, renal failure and ALB is of good discrimination andaccuracy, which was of clinical significance.

Reduction in pulmonary complications in high risk patients undergoing surgery for total hip replacement under general anesthesia by preoperative intensive inspiratory muscle training:A randomized controlled clinical trial

Objective： To evaluate the effects of preoperative inspiratory muscle training （IMT） on the incidence of atelectasis in patients at high risk of postoperative pulmonary complications scheduled for elective total hip replacement surgery under general anesthesia. Methods： Thirty two high-risk patients undergoing elective total hip replacement surgery under general anesthesia were chosen from Nanjing Medical University, Affiliated Nanjing First Hospital. In this single-blind randomized controlled clinical triM, patients were randomly assigned to receive preoperative inspiratory muscle training or conventional treatment （CT）. The major effectiveness outcome variables were atelectasis and duration of postoperative hospitalization. Results： Both groups were comparable prior to surgery. Seven patients in the CT group and 3 in the IMT group developed atelectasis （P = 0.25）. Median duration of postoperative hospitalization was 13 days （range, 10～17 days） in the IMT group versus 16 days （range, 11～23 days） in the CT group （Mann- Whitney U statistics, Z = -2.22, P = 0.03）. Mean postoperative inspiratory pressure was 5% higher in the IMT group. Conclusion： Preoperative intensive inspiratory muscle training appears to reduce the incidence of atelectasis and duration of postoperative hospitalization in patients at high risk of developing postoperative pulmonary complications who were scheduled for elective total hip replacement surgery under general anesthesia.

Evaluation of the Morbidity and Complications of Total Thyroidectomy: Systematic Literature Review

This scientific problem is aiming to talk about the evaluation of morbidity and complications of total thyroidectomy. The presented review was conducted by searching in Medline, Embase, Web of Science, Science Direct, BMJ journal, and Google Scholar for, researches, review articles, and reports, published over the past years, which was searched up to June 2021 for published and unpublished studies and without language restrictions. If limitless lookup had comparable findings, we randomly chosen one or two to keep away from repetitive results. Based on the findings and effects of this review, the success of total thyroidectomy will beautify if we furnish large cognizance to advances in intervention, developing new methods and education. Surgeon responsiveness, nursing training will aid too in accomplishing this goal.

Surgical complications after different therapeutic approaches for locally advanced rectal cancer

BACKGROUND Preoperative radiochemotherapy is widely used in locally advanced rectal cancer.It can improve local control of rectal cancer. However, some researchers believe it increases the incidence of surgical complications. They doubt its safety. Patients with locally advanced rectal cancer receive three different treatments in our hospital, including long-course radiochemotherapy, short-course radiotherapy,and surgery directly. We can compare their differences in postoperative complications.AIM To investigate surgical complications caused by different preoperative radiotherapy regimens.METHODS We retrospectively analyzed 1197 patients admitted between 2008 and 2010 with locally advanced rectal cancer. Three hundred and forty-six patients were treated with preoperative long-course radiochemotherapy(25 × 2 Gy) followed by total mesorectal excision(TME) 6–8 wk later, and 259 patients received short-course radiotherapy(10 × 3 Gy) and subsequently TME 7–10 d later. The remaining 592 patients underwent TME alone without neoadjuvant therapy. According to Clavien–Dindo classification, surgical complications were evaluated for up to 30 d after discharge from hospital.RESULTS There were no deaths in 30 d in all groups after treatment. The majorcomplications were anastomotic leakage and perineal wound complications. The results suggested that both long-course [odds ratio(OR) = 3.624, 95% confidence interval(CI): 1.689–7.775, P = 0.001] and short-course(OR = 5.150, 95%CI:1.828–14.515, P = 0.002) radiotherapy were associated with anastomotic leakage.Temporary ileostomy was a protective factor for anastomotic leakage(OR =6.211, 95%CI: 2.525–15.385, P < 0.001). The severity of anastomotic leakage did not increase in patients following preoperative radiotherapy(P = 0.411).Compared with TME alone, short-course radiotherapy was associated with an increase in perineal wound complications(OR = 5.565, 95%CI: 2.203–14.057, P <0.001), but long-course radiotherapy seemed safe regarding this complication(OR= 1.692, 95%CI: 0.651–4.394, P = 0.280). Although the severity of perineal wound complications increased in patients following short-course radiotherapy(P <0.001), additional intervention was not necessary.CONCLUSION Radiotherapy increased the incidence but not severity of anastomotic leakage.Short-course radiotherapy was also accompanied with perineal wound complications, but intervention appeared unnecessary to ameliorate the complications.

Prognostic nutritional index predicts postoperative complications and long-term outcomes of gastric cancer

AIM: To investigate the impact of prognostic nutritional index (PNI) on the postoperative complications and long-term outcomes in gastric cancer patients undergoing total gastrectomy.

Observation on the Therapeutic Effect and Complication Rate of Totally Laparoscopic Total Gastrectomy and Laparoscopic-Assisted Total Gastrectomy in the Treatment of Gastric Cancer

Objective:To investigate the effect and complication rate of totally laparoscopic and laparoscopic-assisted total gastrectomy in the treatment of gastric cancer.Methods:From March 2019 to July 2021,60 patients with gastric cancer were selected as the subjects in this study;the patients in group A underwent laparoscopic-assisted total gastrectomy,whereas those in group B underwent totally laparoscopic total gastrectomy;the treatment effect and complication rate were compared between the two groups.Results:The postoperative recovery of group B was significantly better than that of group A,and the postoperative complications(10.00%)of group B were significantly lower than that of group A(33.33%)(P<0.05).Conclusion:For patients with gastric cancer,totally laparoscopic total gastrectomy has better therapeutic effect and lower postoperative complications,which is worthy of popularization.

Dislocation of primary total hip arthroplasty:Analysis of risk factors and preventive options

Total hip arthroplasty(THA)is one of the most successful elective operations in orthopedic surgery for improving pain and functional disability in patients with end-stage joint disease.However,dislocation continues to be a troublesome complication after THA,as it is a leading cause of revision and is associated with substantial social,health,and economic costs.It is a relatively rare,usually early occurrence that depends on both the patients’characteristics and the surgical aspects.The most recent and important finding is the special attention to be given preoperatively to spinopelvic mobility,which is closely related to the incidence of dislocation.Consequently,clinical and radiographic assessment of the lumbar spine is mandatory to identify an altered pelvic tilt that could suggest a different positioning of the cup.Lumbar spinal fusion is currently considered a risk factor for dislocation and revision regardless of whether it is performed prior to or after THA.Surgical options for its treatment and prevention include the use of prostheses with large diameter of femoral head size,dual mobility constructs,constrained liners,and modular neck stems.

系统性红斑狼疮患者行人工全髋关节置换术的术后早期安全性研究

目的探究系统性红斑狼疮(systemic lupus erythematosus,SLE)患者接受人工全髋关节置换术(total hip arthroplasty,THA)术后30 d内的安全性。方法回顾性连续纳入2012年6月—2024年4月于北京协和医院接受THA的患者资料,以患者是否伴发SLE分为SLE组和对照组。采用倾向性评分法对两组患者的性别、年龄、手术侧别以1∶1比例进行匹配,比较两组临床特征、术后30 d内主要并发症发生率及同种异体红细胞输注率。结果共入选符合纳入与排除标准的SLE组患者270例,术后30 d内发生并发症18例(6.67%),包括上呼吸道感染2例(0.74%)、肺部感染2例(0.74%)、泌尿系统感染3例(1.11%)、其他系统感染2例(0.74%)、切口愈合不良5例(1.85%)、切口感染1例(0.37%)、消化系统并发症1例(0.37%)、休克1例(0.37%)、SLE活动1例(0.37%),同种异体红细胞输注率为22.59%(61/270)。经倾向性评分匹配后,SLE组和对照组各163例纳入分析:(1)内科合并症方面,与对照组相比,SLE组在骨质疏松、呼吸系统、消化系统、泌尿系统、血液系统和继发或伴发其他风湿性疾病方面具有明显差异(P均<0.05)。(2)术前实验室检查方面,SLE组血小板、淋巴细胞计数、血红蛋白、红细胞压积、白蛋白、血糖和活化部分凝血活酶时间均较对照组低,而C反应蛋白、红细胞沉降率和D-二聚体水平较高(P均<0.05)。(3)手术相关指标方面,SLE组“美国麻醉医师协会分级>2”患者比例更高(15.95%比3.07%,P<0.001),但术中出血量更少[324.7(200.0,500.0)mL比421.8(200.0,500.0)mL,P=0.005]。(4)并发症方面,SLE组主要并发症发生率高于对照组(8.59%比1.23%,P=0.005),相对危险度为1.081(95%CI:1.028~1.136),SLE组同种异体红细胞输注率与对照组无明显差异(25.77%比17.18%,P=0.059)。结论SLE患者接受THA术后30 d主要并发症发生率显著高于非SLE患者,但同种异体红细胞输注率相当。为保证SLE患者THA手术安全性,应尽可能在术前将患者病情控制稳定,并实施严格的围术期管理。

Systematic review and meta-analysis of laparoscopy-assisted and open total gastrectomy for gastric cancer

AIM:To evaluate the safety and efficacy of laparoscopy-assisted total gastrectomy(LATG)and open total gastrectomy(OTG)for gastric cancer.METHODS:A comprehensive search of PubMed,Cochrane Library,Web of Science and BIOSIS Previews was performed to identify studies that compared LATG and OTG.The following factors were checked:operating time,blood loss,harvested lymph nodes,flatus time,hospital stay,mortality and morbidity.Data synthesis and statistical analysis were carried out using RevMan 5.1 software.RESULTS:Nine studies with 1221 participants were included(436 LATG and 785 OTG).Compared to OTG,LATG involved a longer operating time[weighted mean difference(WMD)=57.68 min,95%CI:30.48-84.88;P<0.001];less blood loss[standard mean difference(SMD)=-1.71;95%CI:-2.48--0.49;P<0.001];earlier time to flatus(WMD=-0.76 d;95%CI:-1.22--0.30;P<0.001);shorter hospital stay(WMD=-2.67d;95%CI:-3.96--1.38,P<0.001);and a decrease in medical complications(RR=0.41,95%CI:0.19-0.90,P=0.03).The number of harvested lymph nodes,mortality,surgical complications,cancer recurrence rate and long-term survival rate of patients undergoing LATG were similar to those in patients undergoing OTG.CONCLUSION:Despite a longer operation,LATG can be performed safely in experienced surgical centers with a shorter hospital stay and fewer complications than open surgery.

Direct anterior total hip arthroplasty:Comparative outcomes and contemporary results

Direct anterior total hip arthroplasty has become increasingly more popular among arthroplasty surgeons,in large part due to the use of an intramuscular interval and desire to reduce soft tissue damage.Several studies have now been published comparing the anterior intramuscular to other commonly used approaches,and many studies have published complication rates on large series of patients.Review of comparative studies indicates direct anterior hips tend towards shorter hospital stays and high rates of patients discharged to home.Although some studies show evidence of early benefit in functional outcomes,there is no strong evidence that the anterior approach provides any long term functional improvements compared to other approaches.Additionally,evidence to support reduced damage to soft tissue may not translate to certain clinical significance.Rates of intra-operative femur fracture,operative time and blood loss rates are notably higher for those developing familiarity with this approach.However,when surgeons have performed a modest number of procedures,the complication rates tend to markedly decrease in most studies to levels comparable to other approaches.Accuracy of component positioning also favors the anterior approach in some studies.This review summarizes the available literature comparing the direct anterior to other approaches for total hip arthroplasty and provides a comprehensive summary of common complications.

Drainage after total thyroidectomy or lobectomy for benign thyroidal disorders

Objective: This prospective randomized clinical trial was conducted to evaluate the necessity of drainage after total thyroidectomy or lobectomy for benign thyroidal disorders. Methods: A total of 116 patients who underwent total thyroidectomy or lobectomy for benign thyroidal disorders were randomly allocated to be drained or not. Operative and postoperative outcomes including operating time, postoperative pain assessed by visual analogue scale (VAS), total amount of intramuscular analgesic administration, hospital stay, complications, necessity for re-operation and satisfaction of patients were all assessed. Results: The mean operating time was similar between two groups (the drained and non-drained groups). The mean VAS score was found to be significantly low in the non-drained group patients in postoperative day (POD) 0 and POD 1. The mean amount of intramuscular analgesic requirement was significantly less in the non-drained group. One case of hematoma, two cases of seroma and three cases of transient hypoparathyroidism occurred in the non-drained group, whereas one case of hematoma, two cases of seroma, two cases of wound infections and two cases of transient hypoparathyroidism occurred in the drained group. No patient needed re-operation for any complication. The mean hospital stay was significantly shorter and the satisfaction of patients was superior in the non-drained group. Conclusion: These findings suggest that postoperative complications cannot be prevented by using drains after total thyroidectomy or lobectomy for benign thyroid disorders. Furthermore, the use of drains may increase postoperative pain and the analgesic requirement, and prolong the hospital stay. In the light of these findings, the routine use of drains might not be necessary after thyroid surgery for benign disorders.

Total thyroidectomy is safer with identification of recurrent laryngeal nerve

Objective:To investigate the effect of recurrent laryngeal nerve(RLN)identification on the complications after total thyroidectomy and lobectomy.Methods:Total 134 consecutive patients undergoing total thyroidectomy or thyroid lobectomy from January 2003 to November 2004 were investigated retrospectively.Patients were divided into two groups:RLN identified (Group A)or not(Group B).The two groups were compared for RLN injury and hypocalcaemia.Results:The numbers of patients and nerves at risk were 71 and 129 in Group A,and 63 and 121 in Group B,respectively.RLN injury in Group A(0)was sig- nificantly lower than that in Group B(57.9%)patients,75.8%nerves)for the numbers of patients(P=0.016)and nerves at risk (P=0.006).Temporary hypocalcaemia was significantly higher in Group A than in Group B(1424.1%vs 610.3%,P=0.049). Permanent complications in Group B were significantly higher than those in Group A(1320.6%vs 45.6%,P=0.009).Con- clusion:RLN injury was prevented and permanent complications were decreased by identifying the whole course and branches of the recurrent laryngeal nerve during total thyroidectomy.

Shanghai expert consensus on totally implantable access ports 2019

Totally implantable access ports(TIAPs)are used for patients with poor peripheral vascular support requiring central venous access.In recent years,TIAPs have been gradually accepted and promoted by patients,doctors,and nurses owing to their advantages of convenient carrying,a long maintenance period,low complications,and a high quality of life for patients.Currently,medical personnel that handle TIAP implantation and management in China are from different areas of healthcare,including surgery,internal medicine,radiology,nurse anesthesia,vascular access,etc.,and many only handle TIAP as a part of their duties.Therefore,the operating procedures and steps for the diagnosis and treatment of complications of TIAP vary from person to person,resulting in different incidence and treatment methods for complications in the implantation and use of TIAP in different medical units.Based on this,we have updated the Shanghai expert consensus on TIAPs from 2015 and explored the diagnosis and treatment procedures of related complications while continuing to emphasize standardized implantation and maintenance.

Impact of postoperative glycemic control and nutritional status on clinical outcomes after total pancreatectomy

AIM To evaluate the impact of glycemic control and nutritional status after total pancreatectomy(TP) on complications, tumor recurrence and overall survival.METHODS Retrospective records of 52 patients with pancreatic tumors who underwent TP were collected from 2007 to 2015. A series of clinical parameters collected before and after surgery, and during the follow-up were evaluated. The associations of glycemic control and nutritional status with complications, tumor recurrence and long-term survival were determined. Risk factors for postoperative glycemic control and nutritional status were identified.RESULTS High early postoperative fasting blood glucose(FBG) levels(OR = 4.074, 95%CI: 1.188-13.965, P = 0.025) and low early postoperative prealbumin levels(OR = 3.816, 95%CI: 1.110-13.122, P = 0.034) were significantly associated with complications after TP. Postoperative Hb A1 c levels over 7%(HR = 2.655, 95%CI: 1.299-5.425, P = 0.007) were identified as one of the independent risk factors for tumor recurrence. Patients with postoperative Hb A1 c levels over 7% had much poorer overall survival than those with Hb A1 c levels less than 7%(9.3 mo vs 27.6 mo, HR = 3.212, 95%CI: 1.147-8.999, P = 0.026). Patients with long-term diabetes mellitus(HR = 15.019, 95%CI: 1.278-176.211, P= 0.031) and alcohol history(B = 1.985, SE = 0.860, P = 0.025) tended to have poor glycemic control and lower body mass index levels after TP, respectively.CONCLUSION At least 3 mo are required after TP to adapt to diabetes and recover nutritional status. Glycemic control appears to have more influence over nutritional status on longterm outcomes after TP. Improvement in glycemic control and nutritional status after TP is important to prevent early complications and tumor recurrence, and improve survival.

S-adenosylmethionine in treatment of cholestasis after total parenteral nutrition: laboratory investigation and clinical application

Objective: To observe the effects of S-adenosylmethio-nine (SAMe) in the treatment of cholestasis after totalparenteral nutrition (TPN).Methods: Thirty SD rats were randomly divided intocontrol group, hypercalorie group, hypercalorie+SAMegroup, sepsis group and sepsis+SAMe group to com-pare their states of cholestasis. Sixteen patients re-ceived SAMe because of cholestasis after prolongedTPN, and the therapeutic efficacy was observed.Results: Bile flow was obviously decreased and theserum levels of total bile acid and gamma-glutamyltranspeptidase(γ-GT) were markedly increased in thehypercalorie and sepsis groups. Meanwhile, hepatocytefatty degeneration, dilatation of cholangioles, and bilesludge could be seen microscopically. SAMe adminis-tration in the hypercalorie+SAMe and sepsis+SAMegroups could increase the bile flow, decrease theserum levels of total bile acid and γ-GT, reduce thepathological damage to the liver, and clear the bilesludge in the cholangioles. Cholestasis and abnormalliver function were the main manifestations of the 16patients before SAMe administration. After SAMe treat-ment for 3 weeks, serum levels of total bilirubin, al-kaline phosphatase(AKP), γ-GT, alanine aminotrans-ferase(ALT), and aspartate aminotransferase(AST)were obviously decreased, and normalized in the 4thweek.Conclusion: SAMe could prevent and treat cholestasiswithout discontinuation of TPN.

Conversion total hip arthroplasty: Primary or revision total hip arthroplasty

Total hip arthroplasty(THA) is an increasingly common procedure among elderly individuals.Although conversion THA is currently bundled in a diagnosis related group(DRG) with primary THA,there is a lack of literature supporting this classification and it has yet to be identified whether conversion THA better resembles primary or revision THA.This editorial analyzed the intraoperative and postoperative factors and functional outcomes following conversion THA,primary THA,and revision THA to understand whether the characteristics of conversion THA resemble one procedure or the other,or are possibly somewhere in between.The analysis revealed that conversion THA requires more resources both intraoperatively and postoperatively than primary THA.Furthermore,patients undergoing conversion THA present with poorer functional outcomes in the long run.Patients undergoing conversion THA better resemble revision THA patients than primary THA patients.As such,patients undergoing conversion THA should not be likened to patients undergoing primary THA when determining risk stratification and reimbursement rates.Conversion THA procedures should be planned accordingly with proper anticipation of the greater needs both in the operating room,and for in-patient and followup care.We suggest that conversion THA be reclassified in the same DRG with revision THA as opposed to primary THA as a step towards better allocation of healthcare resources for conversion hip arthroplasties.