Revision THA in obese patients is associated with high re-operation rates at short-term follow-up

Risk factors for liner wear and head migration in total hip arthroplasty: a systematic review

Total hip arthroplasty (THA) is a successful orthopaedic surgical procedure, and its longevity depends on bearing components and implant fixation. Optimizing polyethylene and ceramics has led to improved wear parameters and contributed to improved long-term outcomes. The present systematic review investigated whether time span from implantation, patient characteristics and performance status exert an influence on liner wear and head migration in THA. This study was conducted in conformity to the 2020 PRISMA guidelines. All the clinical investigations which reported quantitative data on the amount of liner wear and head migration in THA were considered. Only studies which reported quantitative data at least on one of the following patient characteristics were suitable: mean age, mean BMI (kg/m2), sex, side, time span between the index THA and the last follow-up (months) were eligible. A multiple linear model regression analysis was employed to verify the association between patient characteristics and the amount of liner wear and/or head migration. The Pearson Product-Moment Correlation Coefficient was used to assess the association between variables. Data from 12,629 patients were considered. The mean length of the follow-up was 90.5 ± 50.9 months. The mean age of patients at surgery was 58.4 ± 9.4 years, and the mean BMI was 27.2 ± 2.5 kg/m2. 57% (7199 of 12,629 patients) were women, and in 44% (5557 of 12,629 patients) THAs were performed on the left. The mean pre-operative Harris hip score was 46.5 ± 6.0 points. There was evidence of a moderate positive association between the amount of liner wear and the time elapsed between the index surgery to the follow-up (P = 0.02). There was evidence of a moderate positive association between the amount of head migration and the time elapsed between the index surgery to the follow-up (P = 0.01). No further statistically significant association was found. The time elapsed between the index surgery to the follow-up was the most important factor which influence the head migration and liner wear in THA. Patients' characteristics and preoperative physical activity did not influence the amount of head migration and liner wear.

Morbid Obesity Is a Risk Factor for Infection Recurrence Following Debridement, Antibiotics, and Implant Retention for Periprosthetic Joint Infection

BACKGROUND

Although morbid obesity is an established risk factor for periprosthetic joint infection following total hip arthroplasty and total knee arthroplasty, little is known regarding the infection control rate of this cohort following debridement, antibiotics, and implant retention (DAIR). The purpose of this study is to investigate the infection control rate following DAIR in a morbidly obese patient cohort compared to a nonobese patient cohort and discern the relationship between time from diagnosis to treatment and risk of DAIR failure.

METHODS

Results of all DAIR procedures were retrospectively reviewed across 4 institutions. Those with a body mass index of at least 40 kg/m² were matched 2:1 on the basis of patient age, sex, date of surgery, and presence of staphylococcal species in culture to a cohort of patients with body mass index of <30 kg/m². Demographic variables were collected for each patient. Kaplan-Meier survivorship curves were constructed and multivariable Cox regression was performed for analysis.

RESULTS

The morbidly obese group experienced a higher treatment failure rate (57.9%) compared to the nonobese group (36.8%; P = .035). Morbid obesity and major depressive disorder/generalized anxiety disorder diagnosis significantly increased the risk of failure, with hazard ratios of 1.82 and 2.09, respectively. Morbidly obese patients who received DAIR within 48 hours of symptom presentation did not face an increased risk of reinfection compared to nonobese patients.

CONCLUSION

Our findings suggest morbidly obese patients face an increased risk of DAIR failure; however, this risk can be mitigated if DAIR is received within 48 hours of symptom onset.

Predictors of Health-Related Quality of Life After Revision Total Hip Arthroplasty for Aseptic Loosening

BACKGROUND

Few studies have investigated the relationships between preoperative or intraoperative patient factors and postoperative quality of life (QOL) after revision total hip arthroplasty (THA). The aim of our study was to identify the predictors of QOL after revision THA for aseptic loosening.

MATERIALS AND METHODS

Fifty-one patients who underwent revision THA for aseptic loosening were included in the present study. Preoperative hip function was evaluated using the Japanese Orthopaedic Association (JOA) score. The patients' QOL after surgery was evaluated with EuroQol 5D (EQ-5D) assessment at the end of the 2-year follow-up. The patients were then divided into two groups: good QOL (score ≥ 0.6) and poor QOL (score < 0.6). Predictive factors (i.e., age, BMI, preoperative JOA score, and the degree of acetabular bone defect according to the Paprosky classification) were compared between both QOL groups. Furthermore, multiple linear regression was performed to assess independent factors affecting the QOL.

RESULTS

Significant differences between the good and poor QOL groups were identified for BMI, walking ability, and severity of acetabular bone defect (BMI: 21.5 ± 2.9 vs. 24.1 ± 4.3, P = 0.0331; walking ability: 11.5 ± 5.0 vs. 5.5 ± 4.9, P = 0.0058; acetabular bone defect: 44.4% vs. 81.0%, P = 0.0103). The walking ability independently affected the EQ-5D utility score.

CONCLUSIONS

The present study indicates that a higher BMI, lower walking ability, and more severe acetabular bone defect are predictors of lower QOL after revision THA for aseptic loosening. In particular, the walking ability was the only independent factor. Thus, surgeons should pay attention to the postoperative management of patients with these risk factors.

Severe Obesity Increases Risk of Infection After Revision Total Hip Arthroplasty

BACKGROUND

The increasing prevalence of obesity has resulted in an increased number of revision total hip arthroplasties (rTHAs) performed in patients with a high body mass index (BMI). The aim of this study is to evaluate whether obesity negatively affects (1) complication rate, (2) reoperation and revision rate, and (3) patient-reported outcome in rTHA.

METHODS

In this registry-based study, we prospectively followed 444 rTHAs (cup: n = 265, stem: n = 57, both: n = 122) performed in a specialized high-volume orthopedic center between 2013 and 2015. The number of complications, and reoperation and revision surgery was registered until 5 years postoperatively. Oxford Hip Score (OHS) was evaluated preoperatively, and at 1 and 2 years postoperatively. Patients were categorized based on BMI to nonobese (<30 kg/m², n = 328), obese (30-35 kg/m², n = 82), and severe obese (≥35 kg/m², n = 34).

RESULTS

Severe obese patients, but not obese patients, had higher risks of complications and re-revision than nonobese patients. In particular, the risk of infection following rTHA was higher in severe obese patients (24%) compared to nonobese patients (3%; relative risk, 7.7). Severe obese patients had overall poorer OHS than nonobese patients, but improvement in OHS did not differ between severe obese and nonobese patients. No differences between obese and nonobese groups on OHS were observed.

CONCLUSION

In our study, severe obesity was associated with an increased risk of infection following rTHA. Patients with high BMI should be counseled appropriately before surgery.

Body mass index is associated with risk of reoperation and revision after primary total hip arthroplasty: a study of the Swedish Hip Arthroplasty Register including 83,146 patients

Background and purpose - The prevalence of obesity is on the rise, becoming a worldwide epidemic. The main purpose of this register-based observational study was to investigate whether different BMI classes are associated with increased risk of reoperation within 2 years, risk of revision within 5 years, and the risk of dying within 90 days after primary total hip arthroplasty (THA). We hypothesized that increasing BMI would increase these risks. Patients and methods - We analyzed a cohort of 83,146 patients who had undergone an elective THA for primary osteoarthritis between 2008 and 2015 from the Swedish Hip Arthroplasty Register (SHAR). BMI was classified according to the World Health Organization (WHO) into 6 classes: < 18.5 as underweight, 18.5-24.9 as normal weight, 25-29.9 as overweight, 30-34.9 as class I obesity, 35-39.9 as class II obesity, and ≥ 40 as class III obesity. Results - Both unadjusted and adjusted parameter estimates showed increasing risk of reoperation at 2 years and revision at 5 years with each overweight and obesity class, mainly due to increased risk of infection. Uncemented and reversed hybrid fixations and surgical approaches other than the posterior were all associated with increased risk. Obesity class III (≥ 40), male sex, and increasing ASA class were associated with increased 90-day mortality. Interpretation - Increasing BMI was associated with 2-year reoperation and 5-year revision risks after primary THA where obese patients have a higher risk than overweight or normal weight patients. As infection seems to be the main cause, customizing preoperative optimization and prophylactic measures for obese patients may help reduce risk.

Early complications of revision total knee arthroplasty in morbidly obese patients

INTRODUCTION

Morbid obesity is a known risk factor for complications and failure following primary total knee arthroplasty. Complications following revision total knee arthroplasty (rTKA) in the morbidly obese (BMI > 40) have not been well described. A retrospective cohort study was designed to investigate the early complications of rTKA in morbidly obese patients.

METHODS

Revision TKA procedures were performed between January 2009 and December 2012 at a single institution. Comparisons were made between patients with a normal BMI (18.5-25) and patients with morbid obesity (BMI > 40).

RESULTS

Thirty-three of 141 morbidly obese patients (23.4%) had a complication compared to 10 of 96 patients with a BMI 18.5-25 (10.4%) (p = 0.011). Morbidly obese patients were younger (69.3 vs. 61.4 years, p < 0.0001), and their most frequent complication in comparison with patients with normal BMI was wound healing problems (p = 0.01).

CONCLUSION

Morbidly obese patients are at a significantly increased rate of early complications following rTKA compared to a normal weight cohort, especially with regard to wound complications. The morbidly obese group was significantly younger at the time of rTKA. In addition, this study highlights the importance of risk stratification for morbidly obese patients undergoing rTKA.

[The hardware techniques for the restoration of the gait stereotype in the patients following total hip replacement: the personalized approach]

BACKGROUND

total hip replacement has long ago become the «golden standard» for the treatment of dysplastic coxarthrosis in thousands of the patients receiving it every year. In the meantime, the analysis of the specialized literature gives evidence of the lack of a systematic and personified approach to the rehabilitation treatment.

AIM

The objective of the present study was to improve medical rehabilitation of the patients following the total hip replacement and to develop the personalized programs for walking modality reconstruction taking into consideration the age and the body weight of the patients.

PATIENTS AND METHODS

A total of 240 patients were available for the observation including 184 women and 56 men. They were divided into three study groups and one control group, with the differentiation into the following three subgroups: one comprised of the patients of moderate acerage age and body weight, the other containing the obese patients (BMI>35), and the third one involving the elderly patients (age >70 years); each subgroup consisted of 20 patients. All the patients received the early basic rehabilitation treatment, those in the study groups had to perform in addition the robotic training based on the use of hardware techniques supplemented by passive mechanotherapy and electromyostimulation designed to restore the walking stereotype with three types of devices: body weight unloading, video-reconstruction associated with biological feedback and robototherapy.

RESULTS

The comparative analysis of the effectiveness of various methods of gait reconstruction has demonstrated the high effectiveness of the application of the hardware technique in the patients of moderate acerage age and body weight. At the same time, the elderly patients had a significantly higher rate of successful walking reconstruction efficiency under the influence of the video-associated training with biological feedback (3 times that achieved with training using the device for unloading the body weight and 4 times compared with the result of a course of robotic walk. The evaluation of the application of the techniques for the gait stereotype reconstruction in the obese patients gave evidence of the advantage of the Lokomat robotic trainings that produced 6 times better results than unloading of the body weight and 5 times better ones than the video-associated training with biological feedback.

DISCUSSION

The results of the present study are on the whole comparable with the data reported by other authors although its design was different from that of the majority of the published studies in that our patients were allocated to different subgroups for the further personalization of the methods applied to restore the gait stereotype. The factors limiting the use of the results of this study include the medium-high level of the patients' welfare most of whom are residents of the city of Moscow and Moscow region characterized by a relatively high quality and accessibility of health care. It means that the results of such studies as the one described in the present article are directly related to the quality and accessibility of health care and can be extrapolated only to the socially safe and well-to-do patients.

CONCLUSIONS

All the hardware techniques are equally effective in the patients of moderate average age and body weight. The elderly patients showed the best results using the video-reconstruction associated with biological feedback, while the Locomat technique was especially useful for the obese patients.

Obesity Is Independently Associated With Early Aseptic Loosening in Primary Total Hip Arthroplasty

BACKGROUND

Obesity affects millions of patients in the United States and is associated with several complications after total hip arthroplasty (THA). The effect of obesity on the rate and mode of primary THA failure remains poorly understood, especially given other potentially confounding patient characteristics. We hypothesized that, among patients with a failed primary THA, obesity is independently associated with aseptic loosening and a higher rate of early revision.

METHODS

Six hundred eighty-four consecutive cases with failed THA referred to a single academic center for revision during a 10-year period were retrospectively reviewed. Multivariate logistic regression analysis was used to test the independent association between obesity and the timing as well as cause of THA failure.

RESULTS

The rate of primary THA failure before 5 years was 48.8% in obese and 37.1% in nonobese patients (odds ratio [OR] = 1.57, P = .010). Primary THA failure before 5 years was more likely with increasing body mass index (BMI) (BMI: 35-40 kg/m², OR = 2.31, P = .008; BMI >40 kg/m², OR = 2.51, P = .049). The rate of primary THA failure for aseptic loosening before 5 years was 30% in obese and 18% in nonobese patients (OR = 1.88, P = .023). Obesity was not a risk for revision for infection, whereas an American Society of Anesthesiologists class ≥3 was independently associated with primary THA failure for infection (OR = 2.33, P < .001).

CONCLUSION

Among patients with a failed THA, comorbidities may account for the risk of revision due to infection in obese patients. Obesity is independently associated with early primary THA failure for aseptic loosening.

Morbid Obesity Is a Significant Risk of Failure Following Revision Total Hip Arthroplasty

BACKGROUND

Although it has been shown that morbidly obese patients experience good outcomes following primary total hip arthroplasty (THA), it is unclear whether this also applies to revision surgery. The purpose of this study was to examine the effect of a high body mass index (BMI) on the outcome of revision THA.

METHODS

We identified 56 patients with a BMI >40 kg/m² who had undergone revision THA between 1994 and 2009 at our hospital (group B). Mean age, BMI, and follow-up were 66.4 years, 45.7 kg/m², and 11.7 years, respectively. This was matched with a second group of patients with a BMI between 30 and 40 kg/m² according to age, gender, and date of index procedure (group A). Mean age, BMI, and follow-up were 66.6 years, 33.6 kg/m², and 12 years, respectively. Outcome measures included the rate of subsequent revision, implant survival, and the Harris hip score (HHS).

RESULTS

Patients with a BMI >40 kg/m² had a significantly increased risk of revision surgery (27% vs 12%, P = .036). Cumulative implant survival was 85% (95% CI, 69-92) in group A and 69% (95% CI, 54-80) in group B at 15 years. HHS increased significantly following surgery in both groups (group A: 26.3-79.3) and (group B: 37.6-69.9; P < .001). However, HHS at last follow-up was significantly higher in group A (79.3 vs 69.9, P = .042).

CONCLUSION

Morbid obesity appears to be associated with an increased risk of failure and lower functional scores following revision THA. Patients should be well informed of this before surgery.

Which factors influence the rate of failure following metal-on-metal hip arthroplasty revision surgery performed for adverse reactions to metal debris? an analysis from the National Joint Registry for England and Wales

Aims

To determine the outcomes following revision surgery of metal-on-metal hip arthroplasties (MoMHA) performed for adverse reactions to metal debris (ARMD), and to identify factors predictive of re-revision.

Patients and Methods

We performed a retrospective observational study using National Joint Registry (NJR) data on 2535 MoMHAs undergoing revision surgery for ARMD between 2008 and 2014. The outcomes studied following revision were intra-operative complications, mortality and re-revision surgery. Predictors of re-revision were identified using competing-risk regression modelling.

Results

Intra-operative complications occurred in 40 revisions (1.6%). The cumulative five-year patient survival rate was 95.9% (95% confidence intervals (CI) 92.3 to 97.8). Re-revision surgery was performed in 192 hips (7.6%). The cumulative five-year implant survival rate was 89.5% (95% CI 87.3 to 91.3). Predictors of re-revision were high body mass index at revision (subhazard ratio (SHR) 1.06 per kg/m² increase, 95% CI 1.02 to 1.09), modular component only revisions (head and liner with or without taper adapter; SHR 2.01, 95% CI 1.19 to 3.38), ceramic-on-ceramic revision bearings (SHR 1.86, 95% CI 1.23 to 2.80), and acetabular bone grafting (SHR 2.10, 95% CI 1.43 to 3.07). These four factors remained predictive of re-revision when the missing data were imputed.

Conclusion

The short-term risk of re-revision following MoMHA revision surgery performed for ARMD was comparable with that reported in the NJR following all-cause non-MoMHA revision surgery. However, the factors predictive of re-revision included those which could be modified by the surgeon, suggesting that rates of failure following ARMD revision may be reduced further.

Cite this article: Bone Joint J 2017;99-B:1020–7.

Predictors of unsuccessful outcome in cemented femoral revisions using bone impaction grafting; Cox regression analysis of 208 cases

INTRODUCTION

Despite improvements in the technique of femoral impaction bone grafting, reconstruction failures still can occur. Therefore, the aim of our study was to determine risk factors for the endpoint re-revision for any reason.

METHODS

We used prospectively collected demographic, clinical and surgical data of all 202 patients who underwent 208 femoral revisions using the X-change Femoral Revision System (Stryker-Howmedica), fresh-frozen morcellised allograft and a cemented polished Exeter stem in our department from 1991 to 2007. Univariable and multivariable Cox regression analyses were performed to identify potential factors associated with re-revision.

RESULTS

The mean follow-up was 10.6 (5-21) years. The cumulative re-revision rate was 6.3% (13/208). After univariable selection, sex, age, body mass index (BMI), American Association of Anesthesiologists (ASA) classification, type of removed femoral component, and mesh used for reconstruction were included in multivariable regression analysis.In the multivariable analysis, BMI was the only factor that was significantly associated with the risk of re-revision after bone impaction grafting (BMI ≥30 vs. BMI &lt;30, HR = 6.54 [95% CI 1.89-22.65]; p = 0.003).

CONCLUSIONS

BMI was the only factor associated with the risk of re-revision for any reason. Besides BMI also other factors, such as Endoklinik score and the type of removed femoral component, can provide guidance in the process of preclinical decision making. With the knowledge obtained from this study, preoperative patient selection, informed consent, and treatment protocols can be better adjusted to the individual patient who needs to undergo a femoral revision with impaction bone grafting.

Morbid Obesity in Total Hip Arthroplasty: Redefining Outcomes for Operative Time, Length of Stay, and Readmission

BACKGROUND

The incidence of obesity among patients presenting for elective total hip arthroplasty (THA) has increased in the last decade, and the relationship between obesity and the need for joint arthroplasty has been demonstrated. This study evaluates the effects of morbid obesity on outcomes after primary THA by comparing short-term outcomes in THA between a morbidly obese (body mass index [BMI] ≥40) and a normal weight (BMI, 18.5 to <25) cohort at our institution between January 2003 and December 2010.

METHODS

Thirty-nine patients included in the morbidly obese group were compared with 186 in the normal weight group. Operative time, length of stay, complications, readmission, and length of readmission were compared.

RESULTS

Operative time was increased in the morbidly obese group at 122 minutes compared with 100 minutes (P = .002). Postoperatively, there was an increased 30-day readmission rate related to surgery of 12.8% associated with BMI ≥40 compared with 2.7% (P = .005) as well as a 5.1-fold increase in surgery-related readmitted bed days-0.32 bed days per patient for normal weight compared with 1.64 bed days per patient for the morbidly obese (P = .026).

CONCLUSION

Morbidly obese patients present a technical challenge and likely this, and the resultant complications are underestimated. More work needs to be performed to enable suitable allocation of resources.

Obesity is Associated With Early Total Hip Revision for Aseptic Loosening

BACKGROUND

Obesity affects more than half a billion people worldwide, including one-third of men and women in the United States. Obesity is associated with higher postoperative complication rates after total hip arthroplasty (THA). It remains unknown whether obese patients progress to revision THA faster than nonobese patients.

METHODS

A total of 257 consecutive primary THAs referred to an academic tertiary care center for revision THA were retrospectively stratified according to preoperative body mass index (BMI), reason for revision THA, and time from primary to revision THA.

RESULTS

When examining primary THAs referred for revision THA, increasing BMI adversely affected the mean time to revision THA. The percentage of primary THAs revised at 5 years was 25% for a BMI of 18-25, 38% for a BMI of 25-30, 56% for a BMI of 30-35, 73% for a BMI of 35-40, and 75% for a BMI of greater than 40 (P < .001). The percentage of primary THAs revised at 15 years was 70%, 82%, 87%, 94%, and 100%, respectively (P < .001). A significant increase in early revision THA for aseptic loosening/osteolysis in obese patients (56%, 23/41) when compared with the nonobese patients (12%, 10/83, P < .001, relative risk ratio = 4.7).

CONCLUSION

Preoperative BMI influences the time of failure of primary THAs referred to an academic tertiary care for revision THA as well as the mechanism of failure. Specifically, obesity increased in the relative risk of early revision THA due to aseptic loosening/osteolysis by 4.7 fold.

Hip Arthroplasty in Obese Patients: Rising Prevalence-Standard Procedures?

We examined our experience and, in particular, complications associated with total hip arthroplasty in obese and morbidly obese patients. We prospectively gathered 50 patients in a matched control series including 25 obese and morbidly obese patients. All patients were operated using the direct lateral approach and standard postoperative protocols. Operating room time, complications, dislocations, blood loss, cup position and clinical parameters using the Harris Hip Score and the Western Ontario and McMaster Universities Arthritis Index results were compared. Although there were some significant differences in clinical outcomes, standard procedures yielded good overall results and an acceptable rate of complications. Details approaching this patient entity are being discussed.

Morbidly Obese vs Nonobese Aseptic Revision Total Hip Arthroplasty: Surprisingly Similar Outcomes

BACKGROUND

We aimed to compare the outcomes between matched morbidly obese (BMI ≥ 40 kg/m(2)) and nonobese (BMI <30 kg/m(2)) patients undergoing first-time aseptic revision THA with at least 4 years of follow-up.

METHODS

Groups were matched 1:1 using sex, age, and date of revision surgery (123 patients in each group).

RESULTS

The overall incidence and risk of complication, reoperation, and re-revision were similar between groups. Morbidly obese patients were more likely to dislocate (odds ratio [OR], 3.3; P = .03), but were less likely to develop polyethylene wear (OR, 0.1; P = .04) and aseptic loosening (OR, 0.3; P = .03).

CONCLUSION

Quality outcome measures such as hospital readmission were not addressed by this study and could be the basis for future studies.

LEVEL OF EVIDENCE

level III, prognostic study.

Obesity is associated with increased postoperative complications after operative management of tibial shaft fractures

OBJECTIVES

To assess the association of obesity and postoperative complications after operative management of tibial shaft fractures.

METHODS

Patients who underwent operative management of a tibial shaft fracture were identified in a national database by Current Procedural Terminology (CPT) codes for: (1) open reduction and internal fixation (ORIF) and (2) intramedullary nailing (IMN) procedures in the setting of International Classification of Diseases, Ninth Revision (ICD-9) codes for tibial shaft fracture. These groups were then divided into non-obese, obese, and morbidly obese cohorts using ICD-9 codes. Each cohort was then assessed for grouped complications within 90 days, removal of implants within 6 months, and nonunion within 9 months postoperatively. Odds ratios and 95% confidence intervals were calculated.

RESULTS

From 2005 to 2012, 14,638 patients who underwent operative management of tibial shaft fractures were identified, including 4425 (30.2%) ORIF and 10,213 (69.8%) IMN. Overall, 1091 patients (7.4%) were coded as obese and 820 (5.6%) morbidly obese. In each operative group, obesity and morbid obesity was associated with a substantial increase in the rate of major and minor medical complications, venous thromboembolism, infection, procedures for implant removal, and nonunion.

CONCLUSIONS

In patients who undergo either ORIF or IMN for tibial shaft fractures, obesity and its related medical comorbidities are associated with significantly increased rates of postoperative medical complications, infection, nonunion, and implant removal compared to non-obese patients.

Superobesity (body mass index >50 kg/m2) and complications after total shoulder arthroplasty: an incremental effect of increasing body mass index

BACKGROUND

The prevalence of obesity in the United States continues to increase. Attention has recently turned to an emerging population of extremely overweight patients, termed superobese and defined as those with body mass index (BMI) ≥50 kg/m(2). The goal of this study was to use a national database to evaluate postoperative complication rates after total shoulder arthroplasty (TSA) in superobese patients and to compare patients of different BMI classes.

METHODS

Patients who underwent TSA or reverse TSA were identified in the PearlDiver database by International Classification of Diseases, Ninth Revision (ICD-9) codes. These patients were then divided into nonobese, obese, morbidly obese, and superobese cohorts by ICD-9 codes. Postoperative complications were assessed and compared between cohorts.

RESULTS

From 2005 to 2012, 144,239 unique patients who underwent TSA or reverse TSA were identified, including 105,661 nonobese patients, 23,864 obese patients, 13,759 morbidly obese patients, and 955 superobese patients. Superobese patients had a significantly higher rate of infection, dislocation, component loosening, revision shoulder arthroplasty, venous thromboembolism, and medical complications after shoulder arthroplasty compared with nonobese controls.

CONCLUSIONS

Obesity is associated with significantly increased rates of numerous complications after TSA, including infection, dislocation, component loosening, revision surgery, venous thromboembolism, and medical complications, compared with nonobese controls. Superobesity (BMI > 50 kg/m(2)) is associated with significantly increased rates of several complications compared with even obese and morbidly obese patients, including infection, component loosening, venous thromboembolism, and medical complications.

When and how do prosthetic hips fail after total hip arthroplasties?-A retrospective study

BACKGROUND/PURPOSE

Understanding failure modes, time to revision, and vulnerable components in revision hips could help reduce the risk of revision surgeries. Our aim was to investigate the association between the index diagnosis and the failure mode in patients undergoing revision surgeries.

METHODS

A total of 402 patients who underwent a first revision surgery in a single hospital between 2000 and 2012 were recruited in a retrospective study. Multiple logistic regression analysis was used to evaluate the association of the index diagnosis of the primary total hip arthroplasty and short-term failure, as well as specific failure mode that occurred early, while controlling for sex, age, and the type of prosthesis.

RESULTS

The mean time to revision due to all failure modes was 9.48 (standard deviation = 6.08) years. Defining short-term failure as a time to revision <5 years after total hip arthroplasty, the primary failure mode was infection (32.4%), followed by loosening (25.7%) and instability (17.1%). In multivariate analysis, as compared to osteonecrosis, patients with index diagnosis as infection was significantly associated with revision due to infection (odds ratio = 9.69, p = 0.013). In addition, osteoarthritis increased the odds of loosening (odds ratio = 4.18, p = 0.012). In contrast to studies in the United States and Europe, acetabular component revisions were the most common type found in our study.

CONCLUSION

This study demonstrates that, compared with patients with osteonecrosis, patients with infection and osteoarthritis had higher odds of revision due to infection and loosening, respectively. Further studies are needed to examine the cause-effect relationship between index diagnosis and mode of failure.