Does Aseptic Revision Risk Differ for Primary Total Knee Arthroplasty Patients Who Have and Do not Have a Prior Primary or Revision Arthroplasty?

BACKGROUND

We sought to evaluate the risk of aseptic revision in total knee arthroplasty (TKA) patients who have and do not have a history of primary or revision arthroplasty of a different major joint.

METHODS

We conducted a matched cohort study using data from Kaiser Permanente's arthroplasty registries. Patients who underwent primary unilateral TKA (index knee) were identified (2009-2018). Two matches based on exposure history were performed: (1) 33,714 TKAs with a history of primary arthroplasty of a different joint (contralateral knee, either hip, and/or either shoulder) were matched to 67,121 TKAs without an arthroplasty history and (2) 597 TKAs with a history of aseptic revision in a different joint were matched to 1,190 TKAs with a history of a prior arthroplasty in a different joint, but without any revision. After the matches were performed, Cox regressions were used to evaluate aseptic revision risk of the index knee using the no history groups as the reference in regression models.

RESULTS

No difference in aseptic revision risk for the index knee was observed when comparing patients who had a prior primary arthroplasty in a different joint to those who did not have an arthroplasty history (hazard ratio = 0.95, 95% CI = 0.86-1.06). Those patients who did not have any prior aseptic revision history in a different joint had higher risk of aseptic revision in the index knee (hazard ratio = 2.06, 95% CI = 1.17-3.63).

CONCLUSION

Patients who had a prior revision history had over a 2-fold higher risk of aseptic revision in the index knee, warranting close surveillance of these patients.

LEVEL OF EVIDENCE

Level III.

The Association Between Cement Viscosity and Revision Risk After Primary Total Knee Arthroplasty

BACKGROUND

Recent case series have reported early failure with the use of high-viscosity cement (HVC) in total knee arthroplasty (TKA). We evaluated revision risk after TKA with HVC compared with medium-viscosity cement (MVC) in a large cohort.

METHODS

We conducted a cohort study using data from Kaiser Permanente's Total Joint Replacement Registry. Patients who underwent fully cemented primary TKA for osteoarthritis were identified (2001-2018). Only posterior-stabilized, fixed-mobility designs of the 3 highest-volume implant systems (DePuy PFC, Zimmer NexGen, and Zimmer Persona) were included to mitigate confounding from implant characteristics. Palacos (Zimmer/Heraeus) and Simplex (Stryker) cements comprised the HVC and MVC exposure groups, respectively. Propensity score-weighted Cox proportional hazards regression was used to evaluate risk for any revision during follow-up and risk for revision from aseptic loosening specifically.

RESULTS

The final cohort comprised 76,052 TKAs, 41.1% using MVC. The crude 14-year cumulative revision probability was 4.55% and 5.12% for TKA with MVC and HVC, respectively. In propensity score-weighted Cox models, MVC compared with HVC had a lower risk of any revision (hazard ratio = 0.82, 95% confidence interval = 0.70-0.95) while no difference was observed for revision from aseptic loosening (hazard ratio = 0.80, 95% confidence interval = 0.56-1.13).

CONCLUSION

While we observed a lower risk for any revision with the use of Simplex MVC compared with Palacos HVC, we did not observe a difference in revision for aseptic loosening specifically. Given the widespread use of HVC, additional research to investigate other HVC and potential mechanisms for failure outside of loosening is warranted.

LEVEL OF EVIDENCE

Level III.

Commercially Prepared Antibiotic-Loaded Bone Cement and Infection Risk Following Cemented Primary Total Knee Arthroplasty

BACKGROUND

The efficacy of commercially available antibiotic-loaded bone cement (ABC) in preventing infection in total knee arthroplasty (TKA) is unclear. We sought to determine the effectiveness of commercially available ABC in reducing the risk of infection following TKA, both overall and among 3 subgroups of patients with a higher risk of infection (diabetes, body mass index ≥35 kg/m, and American Society of Anesthesiologists classification ≥3), and to evaluate the association between the use of ABC and the risks of aseptic revision and revision for aseptic loosening.

METHODS

The Kaiser Permanente Total Joint Replacement Registry was utilized to evaluate 87,018 primary cemented TKAs performed from 2008 to 2016. The primary outcome was time to infection (90-day deep infection or septic revision). Reduced infection risk with ABC relative to regular cement was tested with use of propensity-score-weighted Cox proportional-hazards models with superiority and noninferiority testing. All analyses were replicated for each of the 3 high-risk subgroups. For the secondary revision outcomes, propensity-score-weighted Cox proportional-hazards models were utilized.

RESULTS

Regular cement was found to be noninferior to ABC with respect to risk infection (hazard ratio [HR], 1.14; 95% confidence interval [CI], 0.93 to 1.40) and cost across all TKA patients. However, a lower risk of infection was observed with ABC among TKA patients with diabetes (HR, 0.72; 95% CI, 0.52 to 0.99). There was no evidence of a difference in risk of revision for ABC compared with regular cement.

CONCLUSIONS

We found that the additional cost associated with the use of commercially prepared ABC in primary TKA was not justified in all patients; however, the risk of reduction was lower among patients with diabetes who received ABC. Further study is warranted to identify the efficacy of ABC among other high-risk populations.

LEVEL OF EVIDENCE

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

Association of Type and Frequency of Postsurgery Care with Revision Surgery after Total Joint Replacement

CONTEXT

Postmarket surveillance is limited in the ability to detect medical device problems. Electronic health records can provide real-time information that might help with device surveillance. Specifically, the frequency of postsurgery care might indicate early problems and determine high-risk patients requiring more active surveillance.

OBJECTIVE

To evaluate whether intensity of postsurgery care is associated with revision risk after total joint arthroplasty (TJA).

DESIGN

Using an integrated health care system's TJA registry, we identified primary TJA performed between April 2001 and July 2013 (22,953 knees and 9904 hips). Survival analyses evaluated the frequency of specific types of outpatient and inpatient utilization 0 to 90 and 91 to 180 days postoperatively and revision risk.

MAIN OUTCOME MEASURES

Revision surgery occurring at least 6 months after primary TJA.

RESULTS

Knee arthroplasty recipients with 3 or more outpatient orthopedic allied health/nurse visits within 90 days had a 2.2 times (95% confidence interval [CI] = 1.6-2.9) higher risk of revision within the first 2 years postoperatively and 10.1 times higher risk (95% CI = 7.6-13.3) after 2 years. Compared with hip arthroplasty recipients who had 0 to 3 visits, patients with 6 or more outpatient orthopedic office visits within 90 days had a 15.7 times (95% CI = 5.7-42.9) higher risk of revision. Similar results were observed for 91-day to 180-day visits.

CONCLUSION

Future studies are needed to determine if more specific data on reasons for the higher frequency of outpatient visits can refine these findings and elicit more specific recommendations for TJA devices.

Preoperative Risk Factors for Opioid Utilization After Total Hip Arthroplasty

BACKGROUND

Opioid prescriptions following orthopaedic procedures may contribute to the opioid epidemic in the United States. Risk factors for greater and prolonged opioid utilization following total hip arthroplasty have yet to be fully elucidated. We sought to determine the prevalence of preoperative and postoperative opioid utilization in a cohort of patients who underwent total hip arthroplasty and to identify preoperative risk factors for prolonged utilization of opioids following total hip arthroplasty.

METHODS

A cohort study of patients who underwent primary elective total hip arthroplasty at Kaiser Permanente from January 2008 to December 2011 was conducted. The number of opioid prescriptions dispensed per 90-day period after total hip arthroplasty (up to 1 year) was the outcome of interest. The risk factors evaluated included preoperative analgesic medication use, patient demographic characteristics, comorbidities, and other history of chronic pain. Poisson regression models were used, and relative risks (RRs) and 95% confidence intervals (CIs) are presented.

RESULTS

Of the 12,560 patients who underwent total hip arthroplasty and were identified, 58.5% were female and 78.6% were white. The median age was 67 years (interquartile range, 59 to 75 years). Sixty-three percent of patients filled at least 1 opioid prescription in the 1 year prior to the total hip arthroplasty. Postoperative opioid use went from 88.6% in days 1 to 90 to 24% in the last quarter. An increasing number of preoperative opioid prescriptions was associated with a greater number of prescriptions over the entire postoperative period, with an RR of 1.10 (95% CI, 1.10 to 1.11) at days 271 to 360. Additional factors associated with greater utilization over the entire year included black race, chronic pulmonary disease, anxiety, substance abuse, and back pain. Factors associated with greater utilization in days 91 to 360 (beyond the early recovery phase) included female sex, higher body mass index, acquired immunodeficiency syndrome, peripheral vascular disease, and history of non-specific chronic pain.

CONCLUSIONS

We identified preoperative factors associated with greater and prolonged opioid utilization long after the early recovery period following total hip arthroplasty. Patients with these risk factors may benefit from targeted multidisciplinary interventions to mitigate the risk of prolonged opioid use.

CLINICAL RELEVANCE

Opioid prescriptions following orthopaedic procedures are one of the leading causes of chronic opioid use; strategies to reduce the risk of misuse and abuse are needed. At 1 year postoperatively, almost one-quarter of patients who underwent total hip arthroplasty used opioids in the last 90 days of the first postoperative year, which makes understanding risk factors associated with postoperative opioid utilization imperative.

An international comparison of THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States

Background and purpose - International comparisons of total hip arthroplasty (THA) practices and outcomes provide an opportunity to enhance the quality of care worldwide. We compared THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States. Patients and methods - Primary THAs due to osteoarthritis were identified using Swedish (n = 159,695), Australian (n = 279,693), and US registries (n = 69,641) (2003-2015). We compared patients, practices, and implant usage across the countries using descriptive statistics. We evaluated time to all-cause revision using Kaplan-Meier survival curves. We assessed differences in countries' THA survival using chi-square tests of survival probabilities. Results - Sweden had fewer comorbidities than the United States and Australia. Cement fixation was used predominantly in Sweden and cementless in the United States and Australia. The direct anterior approach was used more frequently in the United States and Australia. Smaller head sizes (≤ 32 mm vs. ≥ 36 mm) were used more often in Sweden than the United States and Australia. Metal-on-highly cross-linked polyethylene was used more frequently in the United States and Australia than in Sweden. Sweden's 5- (97.8%) and 10-year THA survival (95.8%) was higher than the United States' (5-year: 97.0%; 10-year: 95.2%) and Australia (5-year: 96.3%; 10-year: 93.5%). Interpretation - Patient characteristics, surgical techniques, and implants differed across the 3 countries, emphasizing the need to adjust for demographics, surgical techniques, and implants and the need for global standardized definitions to compare THA survivorship internationally.

Opioid Prescribers to Total Joint Arthroplasty Patients Before and After Surgery: The Majority Are Not Orthopedists

BACKGROUND

Improved narcotic pain management after total joint arthroplasty (TJA) is necessary to help battle the opioid epidemic. The goal of this study was to determine the sources of prescriptions prescribed to TJA patients.

METHODS

An evaluation of opioid use in patients undergoing primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) was performed between 2008 and 2012. Using a Total Joint Replacement Registry and pharmacy data, opioids dispensed to TJA patients were identified. The main outcome of interest was who prescribed opioids to patients in the year before and after surgery.

RESULTS

Primary care (pre-TKA 31% TKA, post-TKA 38%, pre-THA 34%, post-THA 40%) and internal medicine (27% pre-TKA, post-TKA 37%, pre-THA 32%, post-THA 40%) were the highest prescribers in the year before, and after, TJA. For TKA patients, orthopedists prescribed 9% of the opioids in the year before surgery, 47% in days 1-90 after surgery, and 14% in days 271-360. Similarly, in THA patients, orthopedists prescribed 14% of the opioids in the year before surgery, 40% in days 1-90 after surgery, and 14% in days 271-360.

CONCLUSION

Patients receive opioid prescriptions from multiple physician types before, and after, TJA. The majority of preoperative, and late postoperative, narcotics were not provided by their surgeons. Orthopedic surgeons may not even know that their TJA patients continue to receive opioids. Coordination of opioid care with health-care providers and greater communication with patients on narcotic use expectations should be promoted.

Patient Factors Associated With Prolonged Postoperative Opioid Use After Total Knee Arthroplasty

BACKGROUND

Pain persists in a moderate proportion of patients after total knee arthroplasty (TKA). Identifying patient factors that are associated with persistent pain may lead to improved care.

PURPOSE

The purpose of the study was to identify preoperative factors associated with increased opioid prescriptions after TKA.

METHODS

A retrospective cohort study of TKAs in an integrated health-care system (January 2008-December 2011) was conducted. The number of opioid prescriptions per 90-day period after TKA (up to 1 year), was the outcome of interest. Patient risk factors that were evaluated included demographics, pain prescriptions, comorbidities, and chronic pain conditions. Multivariable Poisson regression models were employed.

RESULTS

The median age for 23,726 patients was 67 years. Before surgery, 60.0% used opioids. Three months after surgery, 41.2% of patients continued using opioids. Factors associated with greater opioid use included: younger age (odds ratio [OR] = 0.83, 95% confidence interval [CI] 0.82-0.84 per 10-year increase), liver disease (OR = 1.11, 95% CI 1.06-1.16), preoperative nonsteroidal anti-inflammatory drug use (OR = 1.09, 95% CI 1.07-1.10), anxiety (OR = 1.05, 95% CI 1.03-1.08), substance abuse (OR = 1.03, 95% CI 1.00-1.06), diabetes mellitus (OR = 1.03, 95% CI 1.01-1.05), preoperative opioid use (OR = 1.04, 95% CI 1.04-1.04), back pain (OR = 1.23, 95% CI 1.18-1.127), congestive heart failure (OR = 1.16, 95% CI 1.06-1.27), depression (OR = 1.14, 95% CI 1.09-1.18), fibromyalgia (OR = 1.10, 95% CI 1.02-1.18), hypertension (OR = 1.06, 95% CI 1.02-1.10), nonspecific chronic pain (OR = 1.06, 95% CI 1.02-1.10), black race (OR = 1.17, 95% CI 1.12-1.23), and chronic lung disease (OR = 1.05, 95% CI 1.01-1.10).

CONCLUSION

Several preoperative factors were associated with prolonged opioid use after TKA, and their identification can assist providers guide pain management. Avoidance or weaning of preoperative opioids should be considered.

Meta-analysis of individual registry results enhances international registry collaboration

Background and purpose - Although common in medical research, meta-analysis has not been widely adopted in registry collaborations. A meta-analytic approach in which each registry conducts a standardized analysis on its own data followed by a meta-analysis to calculate a weighted average of the estimates allows collaboration without sharing patient-level data. The value of meta-analysis as an alternative to individual patient data analysis is illustrated in this study by comparing the risk of revision of porous tantalum cups versus other uncemented cups in primary total hip arthroplasties from Sweden, Australia, and a US registry (2003-2015). Patients and methods - For both individual patient data analysis and meta-analysis approaches a Cox proportional hazard model was fit for time to revision, comparing porous tantalum (n = 23,201) with other uncemented cups (n = 128,321). Covariates included age, sex, diagnosis, head size, and stem fixation. In the meta-analysis approach, treatment effect size (i.e., Cox model hazard ratio) was calculated within each registry and a weighted average for the individual registries' estimates was calculated. Results - Patient-level data analysis and meta-analytic approaches yielded the same results with the porous tantalum cups having a higher risk of revision than other uncemented cups (HR (95% CI) 1.6 (1.4-1.7) and HR (95% CI) 1.5 (1.4-1.7), respectively). Adding the US cohort to the meta-analysis led to greater generalizability, increased precision of the treatment effect, and similar findings (HR (95% CI) 1.6 (1.4-1.7)) with increased risk of porous tantalum cups. Interpretation - The meta-analytic technique is a viable option to address privacy, security, and data ownership concerns allowing more expansive registry collaboration, greater generalizability, and increased precision of treatment effects.

Persistent Opioid Use Following Total Knee Arthroplasty: A Signal for Close Surveillance

BACKGROUND

Prolonged opioid use following total knee arthroplasty (TKA) has not been extensively studied.

METHODS

A cohort study of primary TKA for osteoarthritis using an integrated healthcare system and Total Joint Replacement Registry (January 2008-December 2011) was conducted. Opioid use during the first year after TKA was the exposure of interest and cumulative daily oral morphine equivalent (OME) amounts were calculated. Total postsurgical OME per 90-day exposure periods were categorized into quartiles. The end point was aseptic revision surgery. Survival analyses were conducted and hazard ratios (HRs) were adjusted for age, gender, prior analgesic use, opioid-related comorbidities, and chronic pain diagnoses.

RESULTS

A total of 24,105 patients were studied. After the initial 90-day postoperative period, 41.5% (N = 9914) continued to use opioids. Also, 155 (0.6%) revisions occurred within 1 year and 377 (1.6%) within 5 years. Compared to patients not taking any opioids, patients using medium-low to high OME after the initial 90-day period had a higher adjusted risk of 1-year revision, ranging from HR = 2.4 (95% confidence interval, 1.3-4.5) to HR = 33 (95% confidence interval, 10-110) depending on the OME and time period.

CONCLUSION

Patients who require opioids beyond 90 days after TKA warrant close follow-up.

Projected increase in total knee arthroplasty in the United States - an alternative projection model

OBJECTIVE

The purpose of our study was to estimate the future incidence rate (IR) and volume of primary total knee arthroplasty (TKA) in the United States from 2015 to 2050 using a conservative projection model that assumes a maximum IR of procedures. Furthermore, our study compared these projections to a model assuming exponential growth, as done in previous studies, for illustrative purposes.

METHODS

A population based epidemiological study was conducted using data from US National Inpatient Sample (NIS) and Census Bureau. Primary TKA procedures performed between 1993 and 2012 were identified. The IR, 95% confidence intervals (CI), or prediction intervals (PI) of TKA per 100,000 US citizens over the age of 40 years were calculated. The estimated IR was used as the outcome of a regression modelling with a logistic regression (i.e., conservative model) and Poisson regression equation (i.e., exponential growth model).

RESULTS

Logistic regression modelling suggests the IR of TKA is expected to increase 69% by 2050 compared to 2012, from 429 (95%CI 374-453) procedures/100,000 in 2012 to 725 (95%PI 121-1041) in 2050. This translates into a 143% projected increase in TKA volume. Using the Poisson model, the IR in 2050 was projected to increase 565%, to 2854 (95%CI 2278-4004) procedures/100,000 IR, which is an 855% projected increase in volume compared to 2012.

CONCLUSIONS

Even after using a conservative projection approach, the number of TKAs in the US, which already has the highest IR of knee arthroplasty in the world, is expected to increase 143% by 2050.

An underlying diagnosis of osteonecrosis of bone is associated with worse outcomes than osteoarthritis after total hip arthroplasty

Background

Well-designed studies of complications and readmission rates in patients undergoing total hip arthroplasty (THA) with osteonecrosis are lacking. Our objective was to examine if a diagnosis of osteonecrosis was associated with complications, mortality and readmission rates after THA.

Methods

We analyzed prospectively collected data from an integrated healthcare system’s Total Joint Replacement Registry of adults with osteonecrosis vs. osteoarthritis (OA) undergoing unilateral primary THA during 2001–2012, in an observational cohort study. We examined mortality (90-day), revision (ever), deep (1 year) and superficial (30-day) surgical site infection (SSI), venous thromboembolism (VTE, 90-day), and unplanned readmission (90-day). Age, gender, race, body mass index, American Society of Anesthesiologists class, and diabetes were evaluated as confounders. We used logistic or Cox regression to calculate odds or hazard ratios (OR, HR) with 95% confidence intervals (CI).

Results

Of the 47,523 primary THA cases, 45,252 (95.2%) had OA, and 2,271 (4.8%) had osteonecrosis. Compared to the OA, patients with osteonecrosis were younger (median age 55 vs. 67 years), and were less likely to be female (42.5% vs. 58.3%) or White (59.8% vs. 77.4%). Compared to the OA, the osteonecrosis cohort had higher crude incidence of 90-day mortality (0.7% vs. 0.3%), SSI (1.2% vs. 0.8%), unplanned readmission (9.6% vs. 5.2%) and revision (3.1% vs. 2.4%). After multivariable-adjustment, patients with osteonecrosis had a higher odds/hazard of mortality (OR: 2.48; 95% CI:1.31–4.72), SSI (OR: 1.67, 95%CI:1.11–2.51), unplanned 90-day readmissions (OR: 2.20; 95% CI:1.67–2.91) and a trend towards higher revision rate 1-year post-THA (HR: 1.32; 95% CI: 0.94–1.84), than OA patients.

Conclusions

Compared to OA, a diagnosis of osteonecrosis was associated with worse outcomes post-THA. A detailed preoperative discussion including the risk of complications is needed for informed consent from patients with osteonecrosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1385-0) contains supplementary material, which is available to authorized users.

Bilateral Simultaneous vs Staged Total Knee Arthroplasty: A Comparison of Complications and Mortality

BACKGROUND

The purpose of this study was to compare the complications and mortality between bilateral simultaneous total knee arthroplasty (BTKA-Simultaneous) and bilateral staged TKA (BTK-Staged) while adjusting for differences in patient, surgeon, and hospital characteristics.

METHODS

An integrated health care system total joint registry was used to compare patients undergoing BTKA-Simultaneous to BTKA-Staged. For outcomes related to revision and infection, the sample included 11,118 patients, and for outcomes of death, acute myocardial infarction, stroke, and venous thromboembolism, a subsample of 7991 patients with comorbidity data was selected.

RESULTS

Overall death and complications in both groups were rare. The complication rates for BTKA-Simultaneous and BTKA-Staged were comparable: aseptic revision (1.17% vs 0.9%), septic revision/deep infection (0.8% vs 0.7%), death (0.28% vs 0.1%), and adverse events (2.49% vs 1.97%). In the adjusted models, there were no significant differences in any of the outcomes between the 2 groups.

CONCLUSION

There is a lack of evidence to support superiority of either BTKA-Simultaneous or BTKA-Staged.

Postoperative opioid use as an early indication of total hip arthroplasty failure

Background and purpose - A criticism of total hip arthroplasty (THA) survivorship analysis is that revisions are a late and rare outcome. We investigated whether prolonged opioid use is a possible indicator of early THA failure. Patients and methods - We conducted a cohort study of THAs registered in a total joint replacement registry from January 2008 to December 2011. 12,859 patients were evaluated. The median age was 67 years and 58% were women. Opioid use in the year after surgery was the exposure of interest, and the cumulative daily amounts of oral morphine equivalents (OMEs) were calculated. Post-THA OMEs per 90 day periods were categorized into quartiles. The endpoints were 1- and 5-year revisions. Results - After the first 90 days, 27% continued to use opioids. The revision rate was 0.9% within a year and 1.7% within 5 years. Use of medium-low (100-219 mg), medium-high (220-533 mg), and high (≥ 534 mg) amounts of OMEs in days 91-180 after surgery was associated with a 6 times (95% confidence interval (CI): 3-15), 5 times (CI: 2-13), and 11 times (CI: 2.9-44) higher adjusted risk of 1 year revision, respectively. The use of medium-low and medium-high amounts of OMEs in days 181-270 after surgery was associated with a 17 times (CI: 6-44) and 14 times (95% CI: 4-46) higher adjusted risk of 1-year revision. There was a similar higher risk of 5-year revision. Interpretation - Persistent postoperative use of opioids was associated with revision THA surgery in this cohort, and it may be an early indicator of potential surgical failures.

Lower Total Knee Arthroplasty Revision Risk Associated With Bisphosphonate Use, Even in Patients With Normal Bone Density

BACKGROUND

Bisphosphonates (BPs) are associated with lower total knee arthroplasty (TKA) revision risk, but the effect of bone mineral density has not been evaluated.

METHODS

A cohort of 34,116 primary TKA patients was evaluated with revision surgery and periprosthetic fractures as end points. BP usage was the exposure of interest. Bone quality (normal, osteopenia, and osteoporosis) and patient age (<65 vs ≥65 years) were evaluated as effect modifiers of risk estimates.

RESULTS

Of the patients, 19.6% were BP users. In BP users, 0.5% underwent an aseptic revision; and 0.6%, a periprosthetic fracture. In non-BP users, 1.6% underwent aseptic revision; and 0.1%, a periprosthetic fracture.

CONCLUSION

Bisphosphonate use was associated with lower risk of revision in all bone quality categories in those older than 65 years. The risk of periprosthetic fractures was higher for patients on BP.

Are There Modifiable Risk Factors for Hospital Readmission After Total Hip Arthroplasty in a US Healthcare System?

BACKGROUND

Although total hip arthroplasty (THA) is a successful procedure, 4% to 11% of patients who undergo THA are readmitted to the hospital. Prior studies have reported rates and risk factors of THA readmission but have been limited to single-center samples, administrative claims data, or Medicare patients. As a result, hospital readmission risk factors for a large proportion of patients undergoing THA are not fully understood.

QUESTIONS/PURPOSES

(1) What is the incidence of hospital readmissions after primary THA and the reasons for readmission? (2) What are the risk factors for hospital readmissions in a large, integrated healthcare system using current perioperative care protocols?

METHODS

The Kaiser Permanente (KP) Total Joint Replacement Registry (TJRR) was used to identify all patients with primary unilateral THAs registered between January 1, 2009, and December 31, 2011. The KPTJRR's voluntary participation is 95%. A logistic regression model was used to study the relationship of risk factors (including patient, clinical, and system-related) and the likelihood of 30-day readmission. Readmissions were identified using electronic health and claims records to capture readmissions within and outside the system. Odds ratio (OR) and 95% confidence intervals (CIs) were calculated. Of the 12,030 patients undergoing primary THAs included in the study, 59% (n = 7093) were women and average patient age was 66.5 years (± 10.7).

RESULTS

There were 436 (3.6%) patients with hospital readmissions within 30 days of the index procedure. The most common reasons for readmission were infection and inflammatory reaction resulting from internal joint prosthetic (International Classification of Diseases, 9(th) Revision, Clinical Modification [ICD-9-CM] 996.66, 7.0%); other postoperative infection (ICD-9-CM 998:59, 5.5%); unspecified septicemia (ICD-9-CM 038.9, 4.9%); and dislocation of a prosthetic joint (ICD-9-CM 996.42, 4.7%). In adjusted models, the following factors were associated with an increased likelihood of 30-day readmission: medical complications (OR, 2.80; 95% CI, 1.59-4.93); discharge to facilities other than home (OR, 1.89; 95% CI, 1.39-2.58); length of stay of 5 or more days (OR, 1.80; 95% CI, 1.22-2.65) versus 3 days; morbid obesity (OR, 1.74; 95% CI, 1.25-2.43); surgeries performed by high-volume surgeons compared with medium volume (OR, 1.53; 95% CI, 1.14-2.08); procedures at lower-volume (OR, 1.41; 95% CI, 1.07-1.85) and medium-volume hospitals (OR, 1.81; 95% CI, 1.20-2.72) compared with high-volume ones; sex (men: OR, 1.51; 95% CI, 1.18-1.92); obesity (OR, 1.32; 95% CI, 1.02-1.72); race (black: OR, 1.26; 95% CI, 1.02-1.57); increasing age (OR, 1.03; 95% CI, 1.01-1.04); and certain comorbidities (pulmonary circulation disease, chronic pulmonary disease, hypothyroidism, and psychoses).

CONCLUSIONS

The 30-day hospital readmission rate after primary THA was 3.6%. Modifiable factors, including obesity, comorbidities, medical complications, and system-related factors (hospital), have the potential to be addressed by improving the health of patients before this elective procedure, patient and family education and planning, and with the development of high-volume centers of excellence. Nonmodifiable factors such as age, sex, and race can be used to establish patient and family expectations regarding risk of readmission after THA. Contrary to other studies and the finding of increased hospital volume associated with lower risk of readmission, higher volume surgeons had a higher risk of patient readmission, which may be attributable to the referral patterns in our organization.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Anterior and Anterolateral Approaches for THA Are Associated With Lower Dislocation Risk Without Higher Revision Risk

BACKGROUND

Lack of consensus continues regarding the benefit of anteriorly based surgical approaches for primary total hip arthroplasty (THA). The purpose of this study was to evaluate the risk of aseptic revision, septic revision, and dislocations for various approaches used in primary THAs from a community-based healthcare organization.

QUESTIONS/PURPOSES

(1) What is the incidence of aseptic revision, septic revision, and dislocation for primary THA in a large community-based healthcare organization? (2) Does the risk of aseptic revision, septic revision, and dislocation vary by THA surgical approach?

METHODS

The Kaiser Permanente Total Joint Replacement Registry was used to identify primary THAs performed between April 1, 2001 and December 31, 2011. Endpoints were septic revisions, aseptic revisions, and dislocations. The exposure of interest was surgical approach (posterior, anterolateral, direct lateral, direct anterior). Patient, implant, surgeon, and hospital factors were evaluated as possible confounders. Survival analysis was performed with marginal multivariate Cox models. Hazard ratios (HRs) and 95% confidence intervals (CIs) are reported. A total of 42,438 primary THAs were available for analysis of revision outcomes and 22,237 for dislocation. Median followup was 3 years (interquartile range, 1-5 years). The registry's voluntary participation is 95%. The most commonly used approach was posterior (75%, N = 31,747) followed by anterolateral (10%, N = 4226), direct anterior (4%, N = 1851), and direct lateral (2%, N = 667).

RESULTS

During the study period 785 hips (2%) were revised for aseptic reasons, 213 (0.5%) for septic reasons, and 276 (1%) experienced a dislocation. The revision rate per 100 years of observation was 0.54 for aseptic revisions, 0.15 for septic revisions, and 0.58 for dislocations. There were no differences in adjusted risk of revision (either septic or aseptic) across the different THA approaches. However, the anterolateral approach (adjusted HR, 0.29; 95% CI, 0.13-0.63, p = 0.002) and direct anterior approach (adjusted HR, 0.44; 95% CI, 0.22-0.87, p = 0.017) had a lower risk of dislocation relative to the posterior approach. There were no differences in any of the outcomes when comparing the direct anterior approach with the anterolateral approach.

CONCLUSIONS

Anterior and anterolateral surgical approaches had the advantage of a lower risk of dislocation without increasing the risk of early revision.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Are Nonagenarians Too Old For Total Hip Arthroplasty? An Evaluation of Morbidity and Mortality Within a Total Joint Replacement Registry

A greater number of patients aged 90 and over will become candidates for total hip arthroplasty (THA) as the nonagenarian population continues to grow. This study evaluated the patient characteristics and incidence of postoperative morbidity and mortality of 183 nonagenarian THA patients among 43,543 primary THA patients followed by a total joint replacement registry. Nonagenarians had a greater number of comorbidities preoperatively, experienced a higher one year mortality and had a longer hospital length of stay. However, nonagenarians did not have an increased risk of infection, deep vein thrombosis or pulmonary embolism and postoperative mortality was within expected rates for individuals 90 years and older. Higher readmission rates, however, highlight the benefits of close follow up during a prolonged postoperative period.

Rheumatoid arthritis is associated with higher ninety-day hospital readmission rates compared to osteoarthritis after hip or knee arthroplasty: a cohort study

OBJECTIVE

To examine whether an underlying diagnosis of rheumatoid arthritis (RA) or osteoarthritis (OA) impacts the 90-day readmission rates after total hip arthroplasty (THA) or total knee arthroplasty (TKA).

METHODS

We analyzed prospectively collected data from an integrated health care system, Total Joint Replacement Registry, of adults with RA or OA undergoing unilateral primary THA or TKA during 2009-2011. Adjusted logistic regression models for 90-day readmission were fit. Odds ratios with 95% confidence intervals (95% CIs) were calculated. Study year was an effect modifier for the outcome; therefore separate analyses were conducted for each of the 3 study years.

RESULTS

Of the 34,311 patients, 496 had RA and 33,815 had OA. Comparisons of RA and OA patients, respectively, were 73% and 61% women, 45% and 70% white, and patients had a mean age of 61 versus 67 years (P < 0.001). Crude 90-day readmission rates for RA and OA were 8.5% and 6.7%, respectively. The adjusted odds of 90-day readmission increased from year to year for RA compared to OA patients, from 0.89 (95% CI 0.46-1.71) in 2009 to 1.34 (95% CI 0.69-2.61) in 2010, and to 1.74 (95% CI 1.16-2.60) in 2011. The 2 most common readmission reasons were joint prosthesis infection (10.2%) and septicemia (10.2%) in RA and joint prosthesis infection (5.7%) and other postoperative infection (5.1%) in OA.

CONCLUSION

RA is a risk factor for 90-day readmission after primary THA or TKA. An increasing risk of readmissions noted in RA in 2011 is concerning and indicates that further studies should examine the reasons for this increasing trend.

Metal-on-conventional polyethylene total hip arthroplasty bearing surfaces have a higher risk of revision than metal-on-highly crosslinked polyethylene: results from a US registry

BACKGROUND

Although studies have reported lower radiological wear in highly crosslinked polyethylene (HXLPE) versus conventional polyethylene in total hip arthroplasty (THA), there is limited clinical evidence on the risk of revision of these polyethylene THA bearing surfaces.

QUESTIONS/PURPOSES

We asked: (1) Do primary THAs with a metal-on-conventional polyethylene bearing surface have a higher risk of revision (all-cause or aseptic) than metal-on-HXLPE? (2) Is the risk of revision (all-cause or aseptic) higher for conventional polyethylene versus HXLPE when the effect of femoral and acetabular components is controlled for in prosthesis-specific analyses?

METHODS

The Kaiser Permanente's Total Joint Replacement Registry was used to identify metal-on-conventional polyethylene and metal-on-HXLPE primary THAs (N = 26,823) performed between April 2001 and December 2011. The registry has 95% voluntary participation and 8% were lost to followup during the 10-year study period. Endpoints of interest were all-cause and aseptic revisions. Descriptive statistics and marginal Cox regression models with propensity score adjustments were applied to compare risk of revision for metal-on-conventional polyethylene versus metal-on-HXLPE THAs and to evaluate two specific manufacturers' hip implant designs while controlling for femoral and acetabular components. Of the 26,823 THAs included in the study, 1815 (7%) were metal-on-conventional polyethylene and 25,008 (93%) were metal-on-HXLPE.

RESULTS

At 7 years followup, the cumulative incidence of revision was 5.4% (95% confidence interval [CI], 4.4%-6.7%) for metal-on-conventional and 2.8% (95% CI, 2.6%-3.2%) for metal-on-HXLPE. There was a higher adjusted risk of all-cause (hazard ratio [HR], 1.75; 95% CI, 1.37-2.24; p < 0.001) and aseptic (HR, 1.91; 95% CI, 1.46-2.50; p < 0.001) revisions among metal-on-conventional polyethylene bearing surface hips compared with metal-on-HXLPE. Results were similar within manufacturer hip designs with the same femoral and acetabular components. Conclusions Metal-on-conventional polyethylene THA bearing surfaces have a higher risk of revision compared with metal-on-HXLPE bearing surfaces. Clinicians should consider the use of HXLPE when using a polyethylene bearing in THA.

LEVEL OF EVIDENCE

Level II, cohort study.

Leveraging Electronic Medical Records for Surveillance of Surgical Site Infection in a Total Joint Replacement Population

Objective.

TO evaluate whether a hybrid electronic screening algorithm using a total joint replacement (TJR) registry, electronic surgical site infection (SSI) screening, and electronic health record (EHR) review of SSI is sensitive and specific for SSI detection and reduces chart review volume for SSI surveillance.

Design.

Validation study.

Setting.

A large health maintenance organization (HMO) with 8.6 million members.

Methods.

Using codes for infection, wound complications, cellullitis, procedures related to infections, and surgeon-reported complications from the International Classification of Diseases, Ninth Revision, Clinical Modification, we screened each TJR procedure performed in our HMO between January 2006 and December 2008 for possible infections. Flagged charts were reviewed by clinical-content experts to confirm SSIs. SSIs identified by the electronic screening algorithm were compared with SSIs identified by the traditional indirect surveillance methodology currently employed in our HMO. Positive predictive values (PPVs), negative predictive values (NPVs), and specificity and sensitivity values were calculated. Absolute reduction of chart review volume was evaluated.

Results.

The algorithm identified 4,001 possible SSIs (9.5%) for the 42,173 procedures performed for our TJR patient population. A total of 440 case patients (1.04%) had SSIs (PPV, 11.0%; NPV, 100.0%). The sensitivity and specificity of the overall algorithm were 97.8% and 91.5%, respectively.

Conclusion.

An electronic screening algorithm combined with an electronic health record review of flagged cases can be used as a valid source for TJR SSI surveillance. The algorithm successfully reduced the volume of chart review for surveillance by 90.5%.

Can total knee arthroplasty be safely performed among nonagenarians? An evaluation of morbidity and mortality within a total joint replacement registry

As the nonagenarian patient population continues to grow, more patients aged 90 and over will become candidates for total knee arthroplasty (TKA). This study evaluated the patient characteristics and incidence of postoperative morbidity and mortality of 216 nonagenarian TKA patients among 81,835 primary TKA patients followed by a total joint replacement registry. Nonagenarians had a greater number of comorbidities preoperatively, experienced a higher rate of deep vein thrombosis and 30 day mortality, and had a longer hospital length of stay. However, nonagenarians did not have an increased risk of infection nor pulmonary embolism and postoperative mortality was within expected rates for individuals 90 years and older. Higher readmission rates, however, highlight the benefits of close follow up during a prolonged postoperative period.

Risk factors for total hip arthroplasty aseptic revision

The purpose of this study was to evaluate patient, operative, implant, surgeon, and hospital factors associated with aseptic revision after primary THA in patients registered in a large US Total Joint Replacement Registry. A total of 35,960 THAs registered from 4/2001-12/2010 were evaluated. The 8-year survival rate was 96.7% (95% CI 96.4%-97.0%). Females had a higher risk of aseptic revision than males. Hispanic and Asian patients had a lower risk of revision than white patients. Ceramic-on-ceramic, ceramic-on-conventional polyethylene, and metal-on-conventional polyethylene bearing surfaces had a higher risk of revision than metal-on-highly cross-linked polyethylene. Body mass index, health status, diabetes, diagnosis, fixation, approach, bilateral procedures, head size, surgeon fellowship training, surgeon and hospital volume were not revision risk factors.

The effect of chronic kidney disease on total hip arthroplasty

Patients with chronic kidney disease (CKD) undergoing total hip arthroplasty (THA) were evaluated for risk of revision, surgical site infection (SSI), thromboembolic events, mortality and readmission. 20,720 primary TKA cases were included (smaller sample for readmission evaluation, N = 9322). The prevalence of CKD among THA patients was 6.1% (N = 1269). After adjustment for age, gender, race, general health, and diabetes, CKD patients were at 1.4 (95% confidence interval 1.1-1.8) increased risk of readmission within 90 days. The adjusted risks for revision (overall, aseptic, and septic), SSI (deep and superficial), deep vein thrombosis, pulmonary embolism, and mortality (30-day, 90-day, ever) were not significantly different between patients with CKD and those without CKD. However, increased risk for 90-day readmission underscores that CKD patients are a fundamentally different population of patients.

Increased risk of revision for high flexion total knee replacement with thicker tibial liners

The outcome of total knee replacement (TKR) using components designed to increase the range of flexion is not fully understood. The short- to mid-term risk of aseptic revision in high flexion TKR was evaluated. The endpoint of the study was aseptic revision and the following variables were investigated: implant design (high flexion vs non-high flexion), the thickness of the tibial insert (≤ 14 mm vs > 14 mm), cruciate ligament (posterior stabilised (PS) vs cruciate retaining), mobility (fixed vs rotating), and the manufacturer (Zimmer, Smith & Nephew and DePuy). Covariates included patient, implant, surgeon and hospital factors. Marginal Cox proportional hazard models were used. In a cohort of 64 000 TKRs, high flexion components were used in 8035 (12.5%). The high flexion knees with tibial liners of thickness > 14 mm had a density of revision of 1.45/100 years of observation, compared with 0.37/100 in non-high flexion TKR with liners ≤ 14 mm thick. Relative to a standard fixed PS TKR, the NexGen (Zimmer, Warsaw, Indiana) Gender Specific Female high flexion fixed PS TKR had an increased risk of revision (hazard ratio (HR) 2.27 (95% confidence interval (CI) 1.48 to 3.50)), an effect that was magnified when a thicker tibial insert was used (HR 8.10 (95% CI 4.41 to 14.89)). Surgeons should be cautious when choosing high flexion TKRs, particularly when thicker tibial liners might be required.

Can total knee arthroplasty be safely performed in patients with chronic renal disease?

BACKGROUND AND PURPOSE

The prevalence of chronic renal disease (CRD) is rising worldwide. Patients with CRD are more likely to have associated medical problems and are at greater risk of postoperative morbidity and mortality. We evaluated patient characteristics and risk of early revision, surgical site infection (SSI), thromboembolic events, mortality, and re-admission of patients with CRD undergoing total knee arthroplasty (TKA). We hypothesized that this patient population would have higher rates of complications.

PATIENTS AND METHODS

We conducted a retrospective analysis of data that had been prospectively collected by a Total Joint Replacement Registry. All primary TKAs performed from 2005 through 2010 were included. 41,852 primary TKA cases were evaluated, of which 2,686 (6.4%) TKA procedures had been performed in CRD patients. Patient characteristics, comorbidities, and general health status were evaluated. Cox proportional hazard regressions and logistic regressions were used to evaluate the association of CRD with outcomes while adjusting for confounding variables. Results - The mean age of the CRD cohort was 67 years and approximately two-thirds of the patients were female. The median follow-up time was 2.1 years. Compared to TKA patients without CRD the CRD patients were older, had poorer general health, and had a higher prevalence of comorbidities. They had a higher incidence of deep SSI (0.9% vs. 0.7%), superficial SSI (0.5% vs. 0.3%), deep vein thrombosis (0.6% vs. 0.4%), any-time mortality (4.7% vs. 2.4%), 90-day mortality (0.4% vs. 0.2%), and 90-day re-admission (10% vs. 6.0%) than patients without CRD. However, after adjustment for confounding variables, CRD patients were at 1.9 times (95% CI: 1.1-3.5) increased risk of superficial SSI, 1.3 times (CI: 1.1-1.6) increased risk of re-admission within 90 days, and 1.5 times (CI: 1.2-1.8) increased risk of mortality at any point after the procedure. The risks of all other complications were not statistically significantly different in patients with CRD compared to patients without CRD.

CONCLUSIONS

CRD patients undergoing TKA have more comorbidities and a higher risk for superficial SSI, 90-day re-admission, and any-time mortality.

Monoblock all-polyethylene tibial components have a lower risk of early revision than metal-backed modular components

BACKGROUND AND PURPOSE

With younger patients seeking reconstructions and the activity-based demands placed on the arthroplasty construct, consideration of the role that implant characteristics play in arthroplasty longevity is warranted. We therefore evaluated the risk of early revision for a monoblock all-polyethylene tibial component compared to a metal-backed modular tibial construct with the same articular geometry in a sample of total knee arthroplasties (TKAs). We evaluated risk of revision in younger patients (< 65 years old) and in older patients (≥ 65 years old).

METHOD

Fixed primary TKAs with implants from a single manufacturer, performed between April 2001 and December 2010, were analyzed retrospectively. Patient characteristics, surgeon, hospital, procedure, and implant characteristics were compared according to tibial component type (monoblock all-polyethylene vs. metal-backed modular). All-cause revisions and aseptic revisions were evaluated. We used descriptive statistics and Cox regression models.

RESULTS

27,657 TKAs were identified, 2,306 (8%) with monoblock and 25,351 (92%) with modular components. In adjusted models, the risk of early all-cause revision (hazard ratio (HR) = 0.5, 95% confidence interval (CI): 0.3-0.8) and aseptic revision (HR = 0.6, CI: 0.3-1.2) was lower for the monoblock cohort than for the modular cohort. In older patients, the early risk of all-cause revision was 0.6 (CI: 0.4-1.0) for the monoblock cohort compared to the modular cohort. In younger patients, the adjusted risk of all-cause revision (HR = 0.3, CI: 0.1-0.7) and of aseptic revision (HR = 0.3, CI: 0.1-0.7) were lower for the monoblock cohort than for the modular cohort.

INTERPRETATION

Overall, monoblock tibial constructs had a 49% lower early risk of all-cause revision and a 41% lower risk of aseptic revision than modular constructs. In younger patients with monoblock components, the early risk of revision for any cause was even lower.

Risk factors for total knee arthroplasty aseptic revision

Using a Total Joint Replacement Registry, patient, operative, implant, surgeon, and hospital risk factors associated with aseptic revision after primary total knee arthroplasty (TKA) were evaluated. From 04/2001 to 12/31/2010 64,017 primary TKA cases, followed for a median time of 2.9 years, were registered and included in the analysis. Patients were predominantly female, white, with osteoarthritis, and obese. The crude aseptic revision rate is 1.3% (N=826). The cumulative survival for aseptic revision at 8 years is 97.6% (95% CI 97.3%-97.8%). Adjusted models revealed that age, race, body mass index, diabetic status, bilateral procedures, high-flex implants, and the LCS mobile bearing knee are associated with risk of revision. Gender, general health status, diagnosis, surgeon fellowship training, surgeon volume, hospital volume, fixation, and bearing surface material were not associated with risk of aseptic revision. Recognition of surgical factors associated with TKA failures can help the surgeons with their choices of surgical techniques and implants.

Risk factors associated with deep surgical site infections after primary total knee arthroplasty: an analysis of 56,216 knees

BACKGROUND

Deep surgical site infection following total knee arthroplasty is a devastating complication. Patient and surgical risk factors for this complication have not been thoroughly examined. The purpose of this study was to evaluate risk factors associated with deep surgical site infection following total knee arthroplasty in a large U.S. integrated health-care system.

METHODS

A retrospective review of a prospectively followed cohort of primary total knee arthroplasties recorded in a total joint replacement registry from 2001 to 2009 was conducted. Records were screened for deep surgical site infection with use of a validated algorithm, and the results were adjudicated by chart review. Patient factors, surgical factors, and surgeon and hospital characteristics were identified with use of the total joint replacement registry. Cox regression models were used to assess risk factors associated with deep surgical site infection.

RESULTS

A total of 56,216 total knee arthroplasties were identified; 63.0% were done in women, the average age of the patients was 67.4 years (standard deviation [SD] = 9.6), and the average body mass index (BMI) was 32 kg/m2 (SD = 6). The incidence of deep surgical site infection was 0.72% (404/56,216). In a fully adjusted model, patient factors associated with deep surgical site infection included a BMI of ≥35 (hazard ratio [HR] = 1.47), diabetes mellitus (HR = 1.28), male sex (HR = 1.89), an American Society of Anesthesiologists (ASA) score of ≥3 (HR = 1.65), a diagnosis of osteonecrosis (HR = 3.65), and a diagnosis of posttraumatic arthritis (HR = 3.23). Hispanic race was protective (HR = 0.69). Protective surgical factors included use of antibiotic irrigation (HR = 0.67), a bilateral procedure (HR = 0.51), and a lower annual hospital volume (HR = 0.33). Surgical risk factors included quadriceps-release exposure (HR = 4.76) and the use of antibiotic-laden cement (HR = 1.53). In a subanalysis, operative time was a risk factor, with a 9% increased risk per fifteen-minute increment.

CONCLUSIONS

Use of a comprehensive infection surveillance system, combined with a total joint replacement registry, identified patient and surgical factors associated with infection following total knee arthroplasty in a large sample. High-risk patients should be counseled, and modifiable clinical conditions should be optimized. Use of antibiotic irrigation should be encouraged, but antibiotic-laden cement may not be useful.

LEVEL OF EVIDENCE

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

Alternative bearings in total knee arthroplasty: risk of early revision compared to traditional bearings: an analysis of 62,177 primary cases

BACKGROUND AND PURPOSE

There is no substantial clinical evidence for the superiority of alternative bearings in total knee arthroplasty (TKA). We compared the short-term revision risk in alternative surface bearing knees (oxidized zirconium (OZ) femoral implants or highly crosslinked polyethylene (HXLPE) inserts) with that for traditional bearings (cobalt-chromium (CoCR) on conventional polyethelene (CPE)). The risk of revision with commercially available HXLPE inserts was also evaluated.

METHODS

All 62,177 primary TKA cases registered in a Total Joint Replacement Registry between April 2001 and December 2010 were retrospectively analyzed. The endpoints for the analysis were all-cause revisions, septic revisions, or aseptic revisions. Bearing surfaces were categorized as OZ-CPE, CoCr-HXLPE, or CoCr-CPE. HXLPE inserts were stratified according to brand name. Confounding was addressed using propensity score weights. Marginal Cox-regression models adjusting for surgeon clustering were used.

RESULTS

The proportion of females was 62%. Average age was 68 (SD 9.3) years, and median follow-up time was 2.8 (IQR 1.2-4.9) years. After adjustments, the risks of all-cause, aseptic, and septic revision with CoCr-HXLPE and OZ-CPE bearings were not statistically significantly higher than with traditional CoCr-CPE bearings. No specific brand of HXLPE insert was associated with a higher risk of all-cause, aseptic, or septic revision compared to CoCr-CPE.

INTERPRETATION

At least in the short term, none of the alternative knee bearings evaluated (CoCr-HXLPE or OZ-CPE) had a greater risk of all-cause, aseptic, and septic revision than traditional CoCr-CPE bearings.

Surgical outcomes of total knee replacement according to diabetes status and glycemic control, 2001 to 2009

BACKGROUND

Poor glycemic control in patients with diabetes may be associated with adverse surgical outcomes. We sought to determine the association of diabetes status and preoperative glycemic control with several surgical outcomes, including revision arthroplasty and deep infection.

METHODS

We conducted a retrospective cohort study in five regions of a large integrated health-care organization. Eligible subjects, identified from the Kaiser Permanente Total Joint Replacement Registry, underwent an elective first primary total knee arthroplasty during 2001 through 2009. Data on demographics, diabetes status, preoperative hemoglobin A1c (HbA1c) level, and comorbid conditions were obtained from electronic medical records. Subjects were classified as nondiabetic, diabetic with HbA1c < 7% (controlled diabetes), or diabetic with HbA1c ≥ 7% (uncontrolled diabetes). Outcomes were deep venous thrombosis or pulmonary embolism within ninety days after surgery and revision surgery, deep infection, incident myocardial infarction, and all-cause rehospitalization within one year after surgery. Patients without diabetes were the reference group in all analyses. All models were adjusted for age, sex, body mass index, and Charlson Comorbidity Index.

RESULTS

Of 40,491 patients who underwent total knee arthroplasty, 7567 (18.7%) had diabetes, 464 (1.1%) underwent revision arthroplasty, and 287 (0.7%) developed a deep infection. Compared with the patients without diabetes, no association between controlled diabetes (HbA1c < 7%) and the risk of revision (odds ratio [OR], 1.32; 95% confidence interval [CI], 0.99 to 1.76), risk of deep infection (OR, 1.31; 95% CI, 0.92 to 1.86), or risk of deep venous thrombosis or pulmonary embolism (OR, 0.84; 95% CI, 0.60 to 1.17) was observed. Similarly, compared with patients without diabetes, no association between uncontrolled diabetes (HbA1c ≥ 7%) and the risk of revision (OR, 1.03; 95% CI, 0.68 to 1.54), risk of deep infection (OR, 0.55; 95% CI 0.29 to 1.06), or risk of deep venous thrombosis or pulmonary embolism (OR, 0.70; 95% CI, 0.43 to 1.13) was observed.

CONCLUSIONS

No significantly increased risk of revision arthroplasty, deep infection, or deep venous thrombosis was found in patients with diabetes (as defined on the basis of preoperative HbA1c levels and other criteria) compared with patients without diabetes in the study population of patients who underwent elective total knee arthroplasty.

Risk factors associated with surgical site infection in 30,491 primary total hip replacements

We examined patient and surgical factors associated with deep surgical site infection (SSI) following total hip replacement (THR) in a large integrated healthcare system. A retrospective review of a cohort of primary THRs performed between 2001 and 2009 was conducted. Patient characteristics, surgical details, surgeon and hospital volumes, and SSIs were identified using the Kaiser Permanente Total Joint Replacement Registry (TJRR). Proportional-hazard regression models were used to assess risk factors for SSI. The study cohort consisted of 30,491 THRs, of which 17,474 (57%) were performed on women. The mean age of the patients in the whole series was 65.5 years (13 to 97; SD 11.8) and the mean body mass index was 29.3 kg/m(2) (15 to 67; SD 5.9). The incidence of SSI was 0.51% (155 of 30,491). Patient factors associated with SSI included female gender, obesity, and American Society of Anesthesiologists (ASA) score ≥ 3. Age, diagnosis, diabetes and race were not associated with SSI. The only surgical factor associated with SSI was a bilateral procedure. Surgeon and hospital volumes, use of antibiotic-laden cement, fixation method, laminar flow, body exhaust suits, surgical approach and fellowship training were not associated with risk of SSI. A comprehensive infection surveillance system, combined with a TJRR, identified patient and surgical factors associated with SSI. Obesity and chronic medical conditions should be addressed prior to THR. The finding of increased SSI risk with bilateral THR requires further investigation.

Risk of revision for fixed versus mobile-bearing primary total knee replacements

BACKGROUND

Mobile-bearing total knee arthroplasty prostheses were developed to reduce wear and revision rates; however, these benefits remain unproven. The purposes of this study were to compare the short-term survivorship and to determine risk factors for revision of mobile-bearing and fixed-bearing total knee replacements.

METHODS

A prospective cohort study of primary total knee arthroplasties performed from 2001 to 2009 was conducted with use of a community total joint replacement registry. Patient characteristics and procedure details were identified. Cox regression models were used. Bearing type was investigated as a risk factor for revision while adjusted for other risk factors such as age, American Society of Anesthesiologists (ASA) score, body mass index, sex, race, diagnosis, bilateral procedures, cruciate-retaining versus posterior-stabilized components, surgical approach, fixation, patellar resurfacing, hospital and surgeon volumes, and fellowship training.

RESULTS

The study cohort consisted of 47,339 total knee arthroplasties, with 62.6% of the procedures in women. Fixed bearings were used in 41,908 knees (88.5%) and mobile bearings in 4830 (10.2%). Rotating-platform designs were used in all mobile-bearing total knee arthroplasties (3112 had a Rotating-Platform Press-Fit Condylar posterior-stabilized design; 1053, a Low Contact Stress [LCS] design; and 665, a Rotating-Platform Press-Fit Condylar cruciate-retaining design). Patients who received fixed-bearing total knee arthroplasty systems were older (mean age, 68.1 years) than those who received mobile-bearing total knee arthroplasty systems (mean age, 62.2 years); the difference was significant (p < 0.001). Overall, 515 knees (1.1%) were revised for reasons other than infection. The survival rate was 97.8% (95% confidence interval [CI], 97.4% to 98.0%) at 6.7 years. The adjusted risk of aseptic revision for the LCS total knee replacements was 2.01 times (95% CI, 1.41 to 2.86) higher than that for fixed-bearing total knee replacements (p < 0.001).There was no significant revision risk for the other mobile-bearing total knee arthroplasty systems. There was no association with surgeon and hospital case volumes and the risk of revision total knee arthroplasty.

CONCLUSIONS

Our study suggests the benefit of potential long-term wear reduction with the LCS implant may not be realized in a community-based setting, where a variety of surgical skills, surgical experience, and diverse patient demographic factors may affect early outcomes.

LEVEL OF EVIDENCE

Therapeutic Level II.

Comparison of the Norwegian knee arthroplasty register and a United States arthroplasty registry

Several national total joint arthroplasty registries exist outside of the United States (U.S.) and have been used to compare rates and outcomes of total knee arthroplasty. Within the U.S., regional arthroplasty registries provide an opportunity to compare U.S. practices and outcomes with those of other countries. The purpose of this study was to compare the demographics, choice of implants, techniques, and outcomes of total knee arthroplasties in Norway to those from a large, U.S. integrated health-care system and to determine the feasibility of using aggregate-level data for international registry comparisons. The study sample consisted of 25,004 primary total knee arthroplasties performed in Norway and 56,208 from the Kaiser Permanente health-care system. Summary-level data were used to compare the two cohorts. At the time of the seven-year follow-up, the cumulative survival of the total knee prosthesis was 94.8% for the arthroplasties performed in Norway and 96.3% for those performed at Kaiser Permanente. The primary reasons for revision arthroplasty included infection, instability, pain, and aseptic loosening. Patient characteristics, selection of implants, surgical techniques, and outcomes differed between the cohorts. Harmonization of data elements and definitions is necessary for future international research.

The role of registry data in the evaluation of mobile-bearing total knee arthroplasty

The conventional wisdom that a mobile-bearing design may offer a benefit compared with a fixed-bearing design in total knee arthroplasty has not been supported by evidence. We reviewed the published literature and annual registry reports of all national and regional registries to determine the differences in clinical outcomes between mobile and fixed-bearing designs. We found only single-center reports and studies with small sample sizes in the published literature. These studies did not demonstrate any advantages of mobile bearings over fixed bearings. Moreover, major national joint registries reported higher failure rates associated with mobile-bearing total knee replacement compared with fixed-bearing total knee replacement. Similar findings from a U.S. national study in a community setting suggest that mobile-bearing knees have an increased risk of revision. After harmonization of methodologies, international collaborations of registries may provide the best insight into the performance of mobile-bearing total knee arthroplasty in real-world settings.

Kaiser Permanente National Total Joint Replacement Registry: aligning operations with information technology

BACKGROUND

A Total Joint Replacement Registry was developed in a large community-based practice to track implant utilization, monitor revisions and complications, identify patients during recalls and advisories, and provide feedback on clinical practices.

QUESTIONS/PURPOSES

We describe the development, implementation, and integration of this Total Joint Replacement Registry, highlighting critical steps in aligning information technology and operations.

METHODS

The primary Total Joint Replacement Registry data source consists of standardized electronic health record forms developed by consensus. The Total Joint Replacement Registry forms are integrated into the clinical workflow (preoperative, intraoperative, and postoperative) and produce a standardized progress note for electronic health record documentation. Secondary data are extracted from other electronic data sources using standard terminologies (ie, ICD-9 codes) to supplement the Total Joint Replacement Registry forms. Electronic screening algorithms are applied to identify complications, in combination with chart review validation and quality control mechanisms.

RESULTS

Three hundred fifty surgeons voluntarily contribute to the registry with 90% participation. The registry has been used for implant recalls and advisories, contract decision making, and identification of patients at risk for revisions (eg, younger patients having total knee arthroplasty). Tracking of overall survival of implants influenced clinical practice, with feedback resulting in the reduction of the number of unicompartmental and uncemented knee arthroplasties performed, usage of femoral head sizes < 28 mm, and the number of minimally invasive surgical procedures performed.

CONCLUSIONS

The Total Joint Replacement Registry has effectively aligned operations with information technology and leveraged that to enhance our ability to respond to recalls and advisories as well as improve quality of care, cost-effectiveness, and create research opportunities.

Does discharge disposition after primary total joint arthroplasty affect readmission rates?

We reviewed 90-day readmission rates for 9150 patients with a primary total hip or knee arthroplasty performed between April 2001 and December 2004. Patients with an American Society of Anesthesiologists score of 3 or greater or with perioperative complications were excluded. We correlated the readmission rate with discharge disposition to either skilled nursing facilities (SNFs) or Home. Of the 9150 patients identified, 1447 were discharged to an SNF. After statistically adjusting for sex, age and American Society of Anesthesiologists scores, total hip arthroplasty and total knee arthroplasty patients discharged to SNFs had higher odds of hospital readmission within 90 days of surgery than those discharged home (total hip arthroplasty: odds ratio = 1.9; 95% confidence interval, 1.2-3.2; P = .008; total knee arthroplasty: odds ratio = 1.6; 95% confidence interval, 1.1-2.4; P = .01). Healthy patients discharged to SNFs after primary total joint arthroplasty need to be followed closely for complications.

Outcomes of routine use of antibiotic-loaded cement in primary total knee arthroplasty

The routine use of antibiotic-loaded bone cement (ALBC) in primary total knee arthroplasty (TKA) is controversial. Outcomes were recorded in patients who underwent primary TKA from May 2003 to March 2007 using a community-based total joint registry. Infection rates were compared in patients undergoing TKA with ALBC and regular cement. A total of 22 889 primary TKA were performed, with 2030 cases (8.9%) using ALBC. Two thousand four hundred forty-nine patients were diabetic (10.7%), with ALBC used in 295 cases (12%). The rate of deep infection was 1.4% for ALBC TKA (28 cases) and 0.7% (154 cases) with regular cement (P = .002). Among patients with diabetes, the infection rate was 1.7% (5 cases) with ALBC and 0.9% (19 cases) with regular cement (P = .199). In patients whom surgeons considered higher risk for infection, ALBC did not appear to reduce TKA infection rates. The routine use of antibiotic-laden cement warrants further investigation.

Knee replacement: epidemiology, outcomes, and trends in Southern California: 17,080 replacements from 1995 through 2004

BACKGROUND AND PURPOSE

There are limited population-based data on utilization, outcomes, and trends in total knee arthroplasty (TKA). The purpose of this study was to examine TKA utilization and short-term outcomes in a pre-paid health maintenance organization (HMO), and to determine whether rates and revision burden changed over time. We also studied whether this population is representative of the general population in California and in the United States.

METHODS

Using hospital utilization and membership databases from 1995 through 2004, we calculated incidence rates (IRs) of primary and revision TKA for every 10,000 health plan members. The demographics of the HMO population were compared to published census data from California and the United States.

RESULTS

The age and sex distributions of the study population were similar to those of the general population in California and the United States. 15,943 primary TKAs and 1,137 revision TKAs were performed during the 10-year period. Patients below the age of 65 accounted for one-third of all primary replacements and one-third of all revision replacements. IRs of primary TKAs increased from 6.3 per 10,000 in 1995 to 11.0 per 10,000 in 2004, at a rate of 5% per year (p<0.001). IRs of revision TKAs increased from 0.41 per 10,000 in 1995 to 0.74 per 10,000 in 2004 (p=0.4). Revision burden remained stable over the 10-year observation period. Surgical complications were higher in revision TKA than in primary TKA (10% vs. 7.7%; p=0.007). 90 day complication rates for primary and revision TKA including death were 0.3% and 0.6% (p=0.1) and for pulmonary embolism 0.5% and 0.4% (p=0.6). 90 day re-admission rates for primary and revision TKA including infection were 0.5% and 4.2% (p<0.001), for myocardial infarction 0.1% each, and for pneumonia 0.2% and 0.4% (p=0.08).

INTERPRETATION

The incidence of primary and revision TKA increased between 1995 and 2005. The rates of postoperative complications were low. Comparisons of the study population and the underlying general populations of interest indicate that this population can be used to predict the incidences and outcomes of TKA in the general population of California and of the United States as a whole.

Reconstruction of major segmental acetabular defects with an oblong-shaped cementless prosthesis: a long-term outcomes study

A retrospective outcomes study was performed on 25 consecutive acetabular reconstructions of major segmental defects by using an oblong-shaped cementless implant. All patients had combined acetabular defects (type III) as defined by the American Academy of Orthopaedic Surgeons classification of acetabular bone deficiency. Long-term follow-up was performed at an average of 11 years postoperatively. Clinical and radiographic outcomes were measured. Failures were defined by component revision or clear radiographic evidence of loosening. Six patients died before final evaluation, and 4 patients did not have complete radiographic data, leaving 14 patients (15 hips) for final analysis. At final follow-up, only 3 of the implants had failed and were revised. There was 1 case of a well-functioning implant with circumferential radiolucency; otherwise, there was no evidence of loosening among the remaining implants.

Early and late manipulation improve flexion after total knee arthroplasty

Manipulations have been considered effective only in the early postoperative period. From a total joint registry containing 9640 primary total knee arthroplasties (TKAs), 195 patients who underwent manipulation under anesthesia (MUA) were identified. A total of 102 had MUA within 90 days (early), and 93 more than 90 days (late) after TKA. Average pain (10-point scale), satisfaction (10-point scale), flexion (degrees), and extension (degrees) were recorded before and after MUA. Flexion was significantly improved after MUA for both groups: early MUA from 68.4 degrees (+/-17.2 degrees ) to 101.4 degrees (+/-16.15 degrees ), P < .001; late MUA from 81.0 degrees (+/-13.3 degrees ) to 98.0 degrees (+/-18.0 degrees ), P = .001. Pain decreased significantly with early MUA from 4.92 (+/-2.25) to 3.34 (+/-2.67) and with late MUA from 4.51 (+/-2.62) to 3.44 (+/-2.78), P = .048. Extension improved only in the early MUA group from 7.15 (+/-10.1) to 2.50 (+/-4.98). Satisfaction scores were not improved. Both early and late manipulation can improve TKA pain and flexion.

Obesity and perioperative morbidity in total hip and total knee arthroplasty patients

The incidence of obesity in 1071 total hip arthroplasty (THA) patients and 1813 total knee arthroplasty (TKA) patients and its effect on perioperative morbidity were evaluated prospectively. Fifty-two percent of TKA and 36% of THA patients were obese (body mass index >or=30). The obese patients were significantly younger, with a higher proportion of obese TKA patients being women. Higher rates of diabetes and hypertension were found in obese patients. Higher postoperative infection rates were observed in patients with body mass index 35 or higher. The odds ratio was 6.7 times higher risk for infection in obese TKA patients and 4.2 times higher for obese THA patients. The increased risk of infection in obese patients undergoing total joint arthroplasty must be realized by both the patient and surgeon.

Cementless implant composition and femoral stress. A finite element analysis

Proximal atrophy and thigh pain are recognized problems with some cementless femoral stems in total hip arthroplasty. It is thought that reduced femoral stress from alterations in load transfer caused by an intramedullary stem contributes to proximal femoral atrophy. An increase in flexural rigidity and bone stress near the stem tip is thought to contribute to thigh pain. A three-dimensional finite element analysis study was performed to calculate stresses in the proximal femur and bone near the stem tip before and after implantation of a collared, proximally coated, cementless femoral prosthesis. The influence of prosthetic material was examined by changing implant composition from cobalt chrome to titanium alloy and leaving all other parameters constant. Femoral stress was increased twofold immediately below the collar with the titanium implant compared with the cobalt chrome. However, the proximal femoral stress in the titanium implanted model was still 1/10 that in the corresponding region of the unimplanted femur model. At the stem tip, as much as a 30% reduction in femoral stress was seen with the titanium stem compared with the cobalt chrome. These findings suggest biomechanical evidence of an advantage for titanium as an implant material compared with cobalt chrome for cementless femoral stems.

Spontaneous repair of superficial defects in articular cartilage in a fetal lamb model

A fetal lamb model was developed to investigate the capacity of fetal articular cartilage for repair after the creation of a superficial defect. Superficial defects, 100 micrometers deep, were made in the articular cartilage of the trochlear groove in the distal aspect of the femur in eighteen fetal lambs that were halfway through the 145-day gestational period; the contralateral limb was used as a sham control. The wounds were allowed to heal in utero for three, seven, fourteen, twenty-one, or twenty-eight days. Seven days after the injury, the defects were filled with a hypocellular matrix, which stained lightly with safranin O. At twenty-eight days, the staining of the matrix was similar to that of the sham controls and the chondrocyte density and the architectural arrangement of the cell layers had been restored. An inflammatory response was not elicited, and no fibrous scar tissue was observed.

Revision total hip arthroplasty with correctional femoral osteotomy in Paget's disease

Varus alignment of the femoral component is associated with femoral component loosening in total hip arthroplasty performed for Paget's disease. Irregular and hemorrhagic bone, along with angular femoral deformity, was encountered during revision total hip arthroplasty in three pagetic patients. A diaphyseal femoral osteotomy facilitated cement removal and provided an opportunity for correction of the deformity. The step-cut configuration of the osteotomy provided intrinsic rotational stability of the femoral segments around a modular, long-stem cementless implant. Excellent clinical and radiographic results were achieved, but moderate blood loss and delayed healing of the osteotomy site were observed.

Tissue expansion for staged reimplantation of infected total knee arthroplasty

Resection arthroplasty of a chronically infected total knee arthroplasty resulted in thin and contracted anterior skin. Expansion of skin using Silastic reservoirs (McGhan Medical, Santa Barbara, CA) facilitated wound closure and rehabilitation following staged total knee reimplantation. Prophylactic expansion of skin around the knee avoided salvage soft tissue procedures such as local and distant tissue flaps.