Whole Blood Metal Levels in the Setting of an Oncologic Endoprosthesis: Is There Cause for Concern?

BACKGROUND: Massive modular endoprostheses have become a primary means of reconstruction after oncologic resection of a lower extremity tumor. These implants are commonly made with cobalt-chromium alloys that can undergo wear and corrosion, releasing cobalt and chromium ions into the surrounding tissue and blood. However, there are few studies about the blood metal levels in these patients. QUESTION/PURPOSE: What is the whole blood cobalt and chromium ion level in patients with massive modular endoprostheses? METHODS: We performed a cross-sectional study of our total joints registry to identify patients with a history of an endoprosthetic reconstruction performed at our institution. Patients who were alive at the time of our review in addition to those undergoing an endoprosthetic reconstruction after an oncologic resection were included. Whole blood samples were obtained from 27 (14 male and 13 female) patients with a history of a lower extremity oncologic endoprosthesis. The median time from surgery to blood collection was 8 years (range 6 months to 32 years). Blood samples were collected and stored in metal-free ethylenediaminetetraacetic acid tubes. Samples were analyzed on an inductively coupled plasma mass spectrometer in an International Organization for Standardization seven-class clean room using polytetrafluoroethylene-coated instruments to reduce the risk of metal contamination. The analytical measuring range was 1 to 200 ng/mL for chromium and cobalt. Cobalt and chromium levels were considered elevated when the blood level was ≥ 1 ppb. RESULTS: Cobalt levels were elevated in 59% (16 of 27) of patients, and chromium levels were elevated in 26% (seven of 27). In patients with elevated metal ion values, 15 of 17 patients had a reconstruction using a Stryker/Howmedica Global Modular Replacement System implant. CONCLUSION: Blood metal levels were elevated in patients who received reconstructions using modular oncology endoprostheses Future work is needed to establish appropriate follow-up routines and determine whether and when systemic complications occur because of elevated metal levels and how to potentially address these elevated levels when complications occur. Prospective and retrospective collaboration between multiple centers and specialty societies will be necessary to address these unknown questions in this potentially vulnerable patient group. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Can the American Joint Replacement Registry Utilize Administrative Claims Data to Accurately Classify Revision Total Hip Arthroplasty (THA) Surgical Diagnoses?

BACKGROUND: The American Joint Replacement Registry (AJRR) is a valuable tool for studying revision total hip arthroplasty (rTHA). Currently, International Classification of Diseases-10 (ICD-10) codes are utilized by the AJRR for classifying surgical diagnoses. However, the validity of this methodology is unknown. The purpose of this study was to determine the accuracy of these codes, as used by AJRR, in classifying rTHA diagnoses. METHODS: We identified 908 rTHAs performed at our institution from 2015 to 2021 using our total joint registry (TJR). Revision diagnoses were obtained from the TJR, which contains prospectively recorded surgical diagnoses collected by trained abstractors, independent from ICD-10 data. The ICD-10 diagnosis codes, as submitted to AJRR, were retrieved for the same procedures. The accuracy of ICD-10 codes for classifying rTHA diagnoses as septic versus aseptic, instability, aseptic loosening, and periprosthetic fracture was assessed using Cohen's Kappa statistic, sensitivity, and specificity. RESULTS: Concordance between AJRR-submitted data and TJR for classifying rTHA as septic or aseptic was excellent (96.9%; k = 0.87). Agreement for aseptic diagnoses varied from very good for instability (k = 0.76) and loosening (k = 0.67) to moderate for periprosthetic fracture (k = 0.54). Specificity was high (>96%) for all 3 aseptic diagnoses, but sensitivity was lower at 74%, 68%, and 44% for instability, loosening, and periprosthetic fracture, respectively. CONCLUSION: The AJRR submitted ICD-10 data correctly classifies the infection status of rTHA procedures with outstanding accuracy, but the accuracy for more granular diagnoses was variable. These data demonstrate the potential for diagnosis specific limitations when utilizing ICD-10 administrative claims for registry reporting.

Longitudinal factors associated with increased alcohol consumption in adults during the COVID-19 pandemic.

Background: Alcohol is the most abused substance among adults in the United States. The COVID-19 pandemic impacted patterns of alcohol use, but data are conflicting, and previous studies are largely limited to cross-sectional analyses.Objective: This study aimed to longitudinally assess sociodemographic and psychological correlates of changes in three patterns of alcohol use (number of alcoholic drinks, drinking regularity, and binge drinking) during COVID-19.Methods: We studied changes in self-reported drinking behaviors in 222,195 Mayo Clinic patients over 21 years of age (58.1% female and 41.9% male) between April 1, 2019, and March 30, 2021. Logistic regression models were used to estimate associations between patient characteristics and change in alcohol consumption.Results: Sociodemographically younger age, White race, having a college degree, and living in a rural area were associated with increased alcohol use regularity (all p < .05). Younger age, male, White, high-school education or less, living in a more deprived neighborhood, smoking, and living in a rural area were associated with increases in number of alcohol drinks (all p ≤ .04) and binge drinking (all p ≤ .01). Increased anxiety scores were associated with increased number of drinks, while depression severity was associated with both increased drinking regularity and increased number of drinks (all p ≤ .02) independent of sociodemographic characteristics.Conclusion: Our study showed that both sociodemographic and psychological characteristics were associated with increased alcohol consumption patterns during the COVID-19 pandemic. Our study highlights specific target groups previously not described in the literature for alcohol interventions based on sociodemographic and psychological characteristics.

Prediction Models for Knee Osteoarthritis: Review of Current Models and Future Directions.

Background: Knee osteoarthritis (OA) is a prevalent joint disease. Clinical prediction models consider a wide range of risk factors for knee OA. This review aimed to evaluate published prediction models for knee OA and identify opportunities for future model development. Methods: We searched Scopus, PubMed, and Google Scholar using the terms knee osteoarthritis, prediction model, deep learning, and machine learning. All the identified articles were reviewed by one of the researchers and we recorded information on methodological characteristics and findings. We only included articles that were published after 2000 and reported a knee OA incidence or progression prediction model. Results: We identified 26 models of which 16 employed traditional regression-based models and 10 machine learning (ML) models. Four traditional and five ML models relied on data from the Osteoarthritis Initiative. There was significant variation in the number and type of risk factors. The median sample size for traditional and ML models was 780 and 295, respectively. The reported Area Under the Curve (AUC) ranged between 0.6 and 1.0. Regarding external validation, 6 of the 16 traditional models and only 1 of the 10 ML models validated their results in an external data set. Conclusion: Diverse use of knee OA risk factors, small, non-representative cohorts, and use of magnetic resonance imaging which is not a routine evaluation tool of knee OA in daily clinical practice are some of the main limitations of current knee OA prediction models.

Diagnostic Performance of Clinical Examination Versus Ultrasonography in the Detection of Developmental Dysplasia of Hip: A Systematic Review and Meta-Analysis.

Background: Developmental dysplasia of the hip (DDH) is a spectrum of diseases involving the femoroacetabular joint. Due to the controversies over the value of different strategies used for DDH screening, this systematic review and meta-analysis aimed to assess the diagnostic performance of standard physical examination maneuvers on the diagnosis of DDH, compared to the Graf ultrasonography (US) method. Methods: PubMed, Web of Science, and SCOPUS databases were searched until the end of October 2020. Studies that (i) used the Ortolani test, Barlow test, or limited hip abduction (LHA) test to assess the risk of DDH in physical examination, (ii)used the Graf US method to examine DDH in sonography, and (iii) provided adequate data to extract the diagnostic performance were included. Pooled sensitivity and specificity were calculated for clinical examinations. Results: A total of 25 studies (72,079 patients in total) were considered eligible to enter the present study. The pooled data of the Ortolani-Barlow test demonstrated a sensitivity of 36% (95% CI:0.25-0.48) and specificity of 98% (95% CI:0.93-0.99). Calculated pooled sensitivity and specificity for the limited hip abduction exam were obtained at 45% (95% CI:0.24-0.69) and 78% (95% CI:0.62-0.88) respectively. A separate analysis of the studies using both exams revealed a sensitivity of 57% (95% CI:0.30-0.82) and a specificity of 95% (95% CI:0.68-0.99). Conclusion: Based on the results, the investigated clinical examinations have high specificity but low sensitivity to detect the DDH; therefore, they have limited application as a screening test. If obliged to rely on clinical examinations for screening, the combination of Ortolani-Barlow and LHA tests can provide more sensitivity than either of these tests performed independently.

Longitudinal Correlates of Increased Alcohol Use Among Adolescents and Young Adults During the COVID-19 Pandemic.

AIMS: The objective of this study is to longitudinally assess sociodemographic and psychological correlates of increased alcohol use during the coronavirus disease of 2019 (COVID-19) period among adolescents and young adults. METHODS: Pre-COVID period is defined as the 1-year period on or before 31 March 2020, and during-COVID period is defined as the period from 1st April 2020 to 30 March 2021. Univariable logistic regression models are used to evaluate the association of demographic characteristics, Area Deprivation Index (ADI), rurality, changes in Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder (GAD-7) scale severity, and the risk of increased alcohol consumption (binge drinking, number of drinks and drinking regularity) from pre-COVID to during-COVID period. RESULTS AND CONCLUSION: Our study found that worsened anxiety symptoms, older age, being in college and current cigarette smoking status were associated with increased alcohol use among youth during the pandemic year. Socioeconomic position (measured by ADI) and rural status were not found to be associated with increased alcohol use among adolescents and young adults.

Conversion of Failed Hemiarthroplasty to Total Hip Arthroplasty Remains High Risk for Subsequent Complications.

BACKGROUND: Few studies have described the outcomes following conversion of failed hemiarthroplasties to total hip arthroplasty (THA) and the impact of mortality when estimating implant survivorship. The aims of this study were to evaluate the following: (1) the risks and predictors of complications, dislocations, reoperations, and revisions and (2) the extent of competing risk of death when evaluating outcomes in patients converted from hemiarthroplasty to THA. METHODS: The study comprised 389 patients treated with conversion THA following hemiarthroplasty for femoral neck fractures between 1985 and 2014. Revision rates were calculated using both the Kaplan-Meier method and cumulative incidence accounting for death as a competing risk. Risk factors were evaluated using Cox regression models. RESULTS: During an average 9.3 years of follow-up, there were 122 complications, 34 dislocations, 69 reoperations, and 51 revisions. Conversion for periprosthetic fractures was associated with a higher risk of reoperations (hazard ratio 4.30, 95% confidence interval 1.94-9.52). Increasing age was a risk factor for reoperations (hazard ratio 1.32, 95% confidence interval 1.10-1.59). No decrease in the rate of complications, dislocations, reoperations, or revisions was observed over the entire 30 years of the study either when evaluating year of surgery as a continuous variable or when comparing specific calendar year intervals (1985-1989, 1990-1999, 2000-2009, 2010-2014) (P > .05). Compared to the cumulative incidence accounting for the competing risk of death, the Kaplan-Meier method overestimated the risk of revision by 7% at 15 years and 10% at 20 years. CONCLUSION: Conversion from hemiarthroplasty to THA remains at high risk for subsequent complications. The cumulative incidence estimate provides a more accurate estimate of revision risk.

Conversion of Hemiarthroplasty to THA Carries an Increased Risk of Reoperation Compared With Primary and Revision THA.

BACKGROUND: There is limited information on the complications and costs of conversion THA after hemiarthroplasty for femoral neck fractures. Previous studies have found that patients undergoing conversion THA experience higher risk complications, but it has been difficult to quantify the risk because of small sample sizes and a lack of comparison groups. Therefore, we compared the complications of patients undergoing conversion THA with strictly matched patients undergoing primary and revision THA. QUESTIONS/PURPOSES: (1) What are the risks of complications, dislocations, reoperations, revisions and periprosthetic fractures after conversion THA compared with primary and revision THA and how has this effect changed over time? (2) What are the length of hospital stay and hospital costs for conversion THA, primary THA, and revision THA? METHODS: Using a longitudinally maintained total joint registry, we identified 389 patients who were treated with conversion THA after hemiarthroplasty for femoral neck fractures between 1985 and 2014. The conversion THA cohort was 1:2 matched on age, sex, and year of surgery to 778 patients undergoing primary THA and 778 patients undergoing revision THA. The proportion of patients having at least 5-year followup was 73% in those who underwent conversion THA, 77% in those who underwent primary THA, and 76% in those who underwent revision THA. We observed a significant calendar year effect, and therefore, compared the three groups across two separate time periods: 1985 to 1999 and 2000 to 2014. We ascertained complications, dislocations, reoperations, revisions and periprosthetic fractures from the total joint registry. Cost analysis was performed using a bottom-up, microcosting methodology for procedures between 2003 and 2014. RESULTS: Patients who converted to THA between 1985 and 1999 had a higher risk of complications (hazard ratio [HR], 2.3; 95% confidence interval [CI], 1.7-3.1; p < 0.001), dislocations (HR, 2.3; 95% CI, 1.3-4.2; p = 0.007), reoperations (HR, 1.7; 95% CI, 1.2-2.5, p = 0.005), and periprosthetic fractures (HR, 3.8; 95% CI, 2.2-6.6; p < 0.001) compared with primary THA. However, conversion THAs during the 1985 to 1999 time period had a lower risk of reoperations (HR, 0.7; 95% CI, 0.5-1.0; p = 0.037), revisions (HR, 0.6; 95% CI, 0.5-0.9; p = 0.014), and periprosthetic fractures (HR, 0.6; 95% CI, 0.4-0.9; p = 0.007) compared with revision THA. The risk differences across the three groups were more pronounced after 2000, particularly when comparing conversion THA patients with revision THA. Conversion THA patients had a higher risk of reoperations (HR, 1.9; 95% CI, 1.0-3.4; p = 0.041) and periprosthetic fractures (HR, 1.7; 95% CI, 1.0-2.9; p = 0.036) compared with revision THA, but there were no differences in the complication risk (HR, 1.4; 95% CI, 0.9-2.1; p = 0.120), dislocations (HR, 1.5; 95% CI, 0.7-3.2; p = 0.274), and revisions (HR, 1.4; 95% CI, 0.7-3.0; p = 0.373). Length of stay for conversion THA was longer than primary THA (4.7 versus 4.0 days; p = 0.012), but there was no difference compared with revision THA (4.7 versus 4.5 days; p = 0.484). Similarly, total inpatient costs for conversion THA were higher than primary THA (USD 22,662 versus USD 18,694; p < 0.001), but there was no difference compared with revision THA (USD 22,662 versus USD 22,071; p = 0.564). CONCLUSIONS: Over the 30 years of the study, conversion THA has remained a higher risk procedure in terms of reoperation compared with primary THA, and over time, it also has become higher risk compared with revision THA. Surgeons should approach conversion THA as a challenging procedure, and patients undergoing this procedure should be counseled about the elevated risks. Furthermore, hospitals should seek appropriate reimbursement for these cases. LEVEL OF EVIDENCE: Level III, therapeutic study.

Low Back Pain in Adults With Transfemoral Amputation: A Retrospective Population-Based Study.

BACKGROUND: Low back pain (LBP) is common among individuals with transfemoral amputation (TFA) and has a negative impact on quality of life. Little is known about health care utilization for LBP in this population and whether utilization varies by amputation etiology. OBJECTIVE: To determine if individuals with TFA have an increased likelihood of seeking care or reporting symptoms of acute or chronic LBP during physician visits after amputation compared with matched individuals without amputation. DESIGN: Retrospective cohort. SETTING: Olmsted County, Minnesota (2010 population: 144 248). PARTICIPANTS: All individuals with incident TFA (N = 96), knee disarticulation, and transfemoral amputation residing in Olmsted County between 1987 and 2014. Each was matched (1:10 ratio) with non-TFA adults on age, sex, and duration of residency. Individuals were divided by etiology of amputation: dysvascular and trauma/cancer. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASUREMENTS: Death and presentation for evaluation of LBP (LBP event) while residing in Olmsted County. LBP events were identified using validated International Classification of Diseases, Ninth Revision (ICD-9) codes and corresponding Berkson, Hospital International Classification of Diseases Adapted (HICDA), and ICD-10 diagnostic codes. Hurdle and competing-risk Cox proportional hazard models were used. RESULTS: Having a TFA of either etiology did appear to correlate with increased frequency of LBP events, although this association was only statistically significant within the dysvascular TFA cohort (dysvascular TFA cohort: relative risk [RR] 1.80, 95% confidence interval [CI] 1.07-3.03, median follow-up 0.78 years; trauma/cancer TFA cohort: RR 1.14, 95% CI 0.58-2.22, median follow-up 7.95 years). In time to event analysis, dysvascular TFA had an increased risk of death and event. Obesity did not significantly correlate with increased frequency of LBP events or time to event for either cohort. At any given point in time, individuals with TFA of either etiology who had phantom limb pain were 90% more likely to have an LBP event (hazard ratio [HR] 1.91, 95% CI 1.11-3.31). Conditional on not dying and no LBP event within the first 2.5 years, individuals with prosthesis had a decreased risk of LBP events in subsequent years. CONCLUSIONS: Risk of LBP events appears to vary by TFA etiology. Obesity did not correlate significantly with increased frequency of LBP event or time to event. Phantom limb pain correlated with decreased time to LBP event after amputation. The association between prosthesis receipt and LBP events is ambiguous. LEVEL OF EVIDENCE: III.

The risk of major cardiovascular events for adults with transfemoral amputation.

BACKGROUND: It is well-known that the risk of cardiac disease is increased for those with lower-limb amputations, likely as a result of the etiology of the amputation. Using a longitudinal population-based dataset, we examined the association between transfemoral amputation (TFA) status and the risk of experiencing a major cardiac event for those undergoing either dysvascular or traumatic amputations. The association of receiving a prosthesis with the risk of experiencing a major cardiac event was also examined. METHODS: Study Population: All individuals with TFA (N 162), i.e. knee disarticulation and transfemoral amputation, residing in Olmsted County, MN, between 1987 and 2014. Each was matched (1:10 ratio) with non-TFA adults on age, sex, and duration of residency. DATA ANALYSIS: A competing risk Cox proportional hazard model was used to estimate the relative likelihood of an individual with a TFA experiencing a major cardiac event in a given time period as compared to the matched controls. The cohort was divided by amputation etiology: dysvascular vs trauma/cancer. Additional analysis was performed by combining all individuals with a TFA to look at the relationship between prosthesis receipt and major cardiac events. RESULTS: Individuals with a dysvascular TFA had an approximately four-fold increased risk of a cardiac event after undergoing an amputation (HR 3.78, 95%CI: 3.07-4.49). These individuals also had an increased risk for non-cardiac mortality (HR 6.27, 95%CI: 6.11-6.58). The risk of a cardiac event was no higher for those with a trauma/cancer TFA relative to the able-bodied controls (HR 1.30, 95%CI: 0.30-5.85). Finally, there was no difference in risk of experiencing a cardiac event for those with or without prosthesis (HR 1.20, 95%CI: 0.55-2.62). CONCLUSION: The high risk of initial mortality stemming from an amputation event may preclude many amputees from cardiovascular disease progression. Amputation etiology is also an important factor: cardiac events appear to be more likely among patients with a dysvascular TFA. Providing a prosthesis does not appear to be associated with a reduced risk of a major cardiac event following amputation.

Does School Screening Affect Scoliosis Curve Magnitude at Presentation to a Pediatric Orthopedic Clinic?

BACKGROUND: With new data supporting the efficacy of bracing, the role of school screening for early detection of moderate scoliosis curves has been revisited. Because of a high rate of false-positive screening and cost concerns, a comprehensive county-wide school screening program was discontinued in 2004. We aim to determine the impact of a comprehensive school screening program on curve magnitude at presentation and initial scoliosis treatment for all local county patients presenting to a pediatric orthopedic clinic from all referral sources. METHODS: Between 1994 and 2014, a total of 761 county patients presented to a pediatric orthopedic clinic for new scoliosis evaluation. Curve magnitude and recommended treatment were recorded. Treatment indications for bracing, surgery, and observation were consistent over the study period. RESULTS: From January 1994 to July 2004 (school screening period), 514 children were seen by a pediatric orthopedic specialist for scoliosis evaluation compared to 247 patients from August 2004 to December 2014 (no school screening). There was a 48% decrease in the number of county children who were evaluated for idiopathic scoliosis by pediatric orthopedics once school screening was discontinued. Mean maximal Cobb angle at presentation increased from 20° (range, 4°-65°) to 23° (range, 7°-57°). At presentation, 5 of 514 (0.97%) patients in the screened group required surgery and 68 of 514 (13.2%) required bracing, compared to 3 of 247 (1.2%) patients in the nonscreened group requiring surgery and 47 of 247 (19%) requiring bracing (p>.05, p=.04, respectively). CONCLUSION: After school screening was discontinued, mean curve magnitude and rates of bracing at presentation statistically increased in county patients evaluated for new scoliosis, although the clinical significance is unclear. After school screening was discontinued, there were fewer patient referrals, braces prescribed, and unnecessary evaluations (patients discharged at first visit). This study provides data to evaluate the role of school screening for children with regular access to health care. LEVEL OF EVIDENCE: Level 3.

Procedural intervention for arthrofibrosis after ACL reconstruction: trends over two decades.

PURPOSE: Arthrofibrosis is a rare complication after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to (1) report a population-based incidence of arthrofibrosis (as defined by manipulation under anaesthesia or surgical lysis of adhesions) following ACL injury and reconstruction, (2) identify risk factors associated with development of arthrofibrosis, and (3) report outcomes of intervention for arthrofibrosis. METHODS: This was a historical cohort study performed in Olmsted County, Minnesota. The Rochester Epidemiology Project (REP) was used to identify a population-based cohort of individuals with new-onset, isolated ACL tears between 1 January 1990 and 31 December 2010. The REP database provides access to all medical records for each resident of Olmsted County, regardless of the facility where the care was delivered. A total of 1841 individuals were identified with new-onset, isolated ACL tears and were confirmed with chart review. The intervention incidence for arthrofibrosis was then calculated, and various predictive factors including age, sex, calendar year, and meniscal injury were investigated. RESULTS: During follow-up, 5 patients (1.0 %) in the non-operative cohort and 23 patients (1.7 %) in the ACL reconstruction cohort received intervention for arthrofibrosis, corresponding to an incidence of 0.7 per 1000 person-years in the non-operative cohort and 1.9 per 1000 person-years in the ACL reconstruction cohort. Female patients were 2.5 times more likely to have arthrofibrosis than males. The mean preoperative range of motion was -8° to 83° and improved to a mean of -2° to 127° post-operatively. CONCLUSIONS: Arthrofibrosis remains a rare but potentially devastating complication after ACL reconstruction, and roughly 2 % of patients had post-operative stiffness that required intervention. Female patients are at higher risk of arthrofibrosis. However, when patients develop severe motion complications after ACL injury, interventions are generally effective in preventing permanent arthrofibrosis.

Incidence and long-term follow-up of isolated posterior cruciate ligament tears.

PURPOSE: Isolated posterior cruciate ligament (PCL) tears are an uncommon injury. The goals of this study are to (1) determine the population-based incidence of isolated PCL tears, (2) compare the occurrence of secondary meniscal tears or arthritis in patients with PCL deficiency to patients without PCL tears, and (3) evaluate factors associated with long-term sequelae among patients with PCL deficiency. METHODS: This retrospective study included a population-based incidence cohort of 48 patients with new-onset, isolated PCL tears between 1990 and 2010, as well as an age and sex-matched cohort of individuals without PCL tears. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. Subjects were retrospectively followed to determine the development of subsequent meniscal tears, arthritis, or total knee arthroplasty (TKA). RESULTS: The age- and sex-adjusted annual incidence of isolated, complete PCL tears was 1.8 (95 % CI 1.3, 2.3) per 100,000. During a mean 12.2-year follow-up, patients with isolated PCL tears had a significantly higher likelihood (HR 6.2, 95 % CI 1.8, 21.2) of symptomatic arthritis compared to individuals without PCL tears. The likelihood of subsequent meniscal tears (HR 2.1, 95 % CI 0.4, 10.7) and TKA (HR 3.2, 95 % CI 0.5, 19.6) was more frequent among patients with PCL tears compared to subjects without PCL tears. Older age at injury was significantly associated with future arthritis (P = 0.003) and TKA (P = 0.02). CONCLUSION: Isolated PCL tears remain a rare injury with an estimated annual incidence of 2 per 100,000 persons. Patients with isolated PCL tears have a significantly higher risk of symptomatic arthritis than patients without PCL tears. Older age at injury is associated with a higher risk of arthritis and the need for TKA. The results of this study can be used to educate patients about the natural history of isolated PCL tears and provide a baseline of expectations for the future development of arthritis and subsequent meniscal injury following isolated PCL injury. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Long-term follow-up of isolated ACL tears treated without ligament reconstruction.

PURPOSE: The incidence of subsequent meniscal tears and arthritis among patients with isolated ACL tears treated without ligament reconstruction has not been clearly established. The purpose of this study was to (1) compare the risk of subsequent meniscal tears and osteoarthritis (OA) between patients with isolated ACL tears treated without ligament reconstruction and a matched cohort of individuals without ACL tears and (2) examine factors predictive of long-term sequelae after non-operative treatment of isolated ACL tears. METHODS: This study compared a population-based incidence cohort of 364 patients with new-onset, isolated ACL tears between 1990 and 2000, to an age and sex-matched cohort of 364 individuals without ACL tears. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. Subjects were retrospectively followed for mean follow-up of 14.3 years (±7.4 years) to determine the development of subsequent meniscal injury, arthritis, or total knee arthroplasty (TKA). RESULTS: Patients treated without ligament reconstruction after ACL tears had a significantly higher risk of secondary meniscal tears (HR 18.0, 95 % CI 9.7, 33.3), arthritis (HR 14.2, 95 % CI 8.0, 25.2), and need of TKA (HR 5.0, 95 % CI 2.1, 12.2) than individuals without ACL tears. Lateral meniscal tear at diagnosis was associated with a higher risk of arthritis (HR 2.7, 95 % CI 1.4, 5.7) and TKA (HR 4.3, 95 % CI 1.3, 13.7). Treatment with meniscectomy was associated with an increased risk of additional meniscal tears (HR 51.5, 95 % CI 10.3, 936.8). CONCLUSIONS: Patients treated non-operatively after isolated ACL tears are at a significantly higher risk of secondary meniscal tears, arthritis, and TKA when compared to age and sex-matched subjects without ACL tears. Additionally, baseline lateral meniscal tears were significantly associated with an increased probability of developing arthritis and the need for TKA. This information may be helpful when counselling patients about the natural history of ACL tears treated without ligament reconstruction. LEVEL OF EVIDENCE: III.

Clinical Factors, Disease Parameters, and Molecular Therapies Affecting Osseointegration of Orthopedic Implants.

Total hip and knee arthroplasty are effective interventions for management of end-stage arthritis. Indeed, about 7 million Americans are currently living with artificial hip and knee joints. The majority of these individuals, however, will outlive their implants and require revision surgeries, mostly due to poor implant osseointegration and aseptic loosening. Revisions are potentially avoidable with better management of patient-related risk factors that affect the osseointegration of orthopedic implants. In this review, we summarize the published clinical literature on the role of demographics, biologic factors, comorbidities, medications and aseptic loosening risk. We focus on several systemic and local factors that are particularly relevant to implant osseointegration. Examples include physiological and molecular processes that are linked to hyperglycemia, oxidative stress, metabolic syndrome and dyslipidemia. We discuss how orthopedic implant osseointegration can be affected by a number of molecular therapies that are antiresorptive or bone anabolic (i.e. calcium, vitamin D, bisphosphonates, calcitonin, strontium, hormone replacement therapy, selective estrogen-receptor modulators).

Predictors of Receiving a Prosthesis for Adults With Above-Knee Amputations in a Well-Defined Population.

BACKGROUND: Prior studies have identified age as a factor in determining an individual's likelihood of receiving a prosthesis following a lower limb amputation. These studies are limited to specific subsets of the general population and are unable to account for preamputation characteristics within their study populations. Our study seeks to determine the effect of preamputation characteristics on the probability of receiving a prosthesis for the general population in the United States. OBJECTIVE: To identify preamputation characteristics that predict of the likelihood of receiving a prosthesis following an above-knee amputation. DESIGN: A retrospective, population-based cohort study. SETTING: Olmsted County, Minnesota (2010 population: 144,248). PARTICIPANTS: Individuals (n = 93) over the age of 18 years who underwent an above-knee amputation, that is, knee disarticulation or transfemoral amputation, while residing in Olmsted County, MN, between 1987 and 2013. METHODS: Characteristics affecting the receipt of a prosthesis were analyzed using a logistic regression and a random forest algorithm for classification trees. Preamputation characteristics included age, gender, amputation etiology, year of amputation, mobility, cognitive ability, comorbidities, and time between surgery and the prosthesis decision. MAIN OUTCOME MEASURES: The association of preamputation characteristics with the receipt of a prosthesis following an above-knee amputation. RESULTS: Twenty-four of the participants received a prosthesis. The odds of receiving a prosthesis were almost 30 times higher in those able to walk independently prior to an amputation relative to those who could not walk independently. A 10-year increase in age was associated with a 53.8% decrease in the likelihood of being fit for a prosthesis (odds ratio = 0.462, P =.030). Time elapsed between surgery and the prosthesis decision was associated with a rise in probability of receiving a prosthesis for the first 3 months in the random forest algorithm. No other observed characteristics were associated with receipt of a prosthesis. CONCLUSIONS: The association of preamputation mobility and age with the likelihood of being fit for a prosthesis is well understood. The effect of age, after controlling for confounders, still persists and is associated with the likelihood of being fit for a prosthesis.

Trends in the epidemiology of osteomyelitis: a population-based study, 1969 to 2009.

BACKGROUND: The epidemiology of osteomyelitis in the United States is largely unknown. The purpose of this study was to determine long-term secular trends in the incidence of osteomyelitis in a population-based setting. METHODS: The study population comprised 760 incident cases of osteomyelitis first diagnosed between January 1, 1969, and December 31, 2009, among residents of Olmsted County, Minnesota. The complete medical records for each potential subject were reviewed to confirm the osteomyelitis diagnosis and to extract details on anatomical sites, infecting organisms, etiological risk factors, and outcomes. RESULTS: The overall age and sex-adjusted annual incidence of osteomyelitis was 21.8 cases per 100,000 person-years. The annual incidence was higher for men than for women and increased with age (p < 0.001). Rates increased with the calendar year (p < 0.001) from 11.4 cases per 100,000 person-years in the period from 1969 to 1979 to 24.4 per 100,000 person-years in the period from 2000 to 2009. The incidence remained relatively stable among children and young adults but almost tripled among individuals older than sixty years; this was partly driven by a significant increase in diabetes-related osteomyelitis from 2.3 cases per 100,000 person-years in the period from 1969 to 1979 to 7.6 cases per 100,000 person-years in the period from 2000 to 2009 (p < 0.001). Forty-four percent of cases involved Staphylococcus aureus infections. CONCLUSIONS: The reasons for the increase in osteomyelitis between 1969 and 2009 are unclear but could comprise a variety of factors, including changes in diagnosing patterns or increases in the prevalence of risk factors (e.g., diabetes) in this population.

Comparative Survivorship of Different Tibial Designs in Primary Total Knee Arthroplasty.

BACKGROUND: Few registry-based studies in the United States have compared the survivorship of different knee implant designs in total knee arthroplasty. The purpose of this study was to compare differences in survivorship of commonly used tibial implant designs in primary total knee arthroplasty. METHODS: A total of 16,584 primary total knee arthroplasties in 11,992 patients were performed at a single institution from 1985 to 2005. Patients were prospectively followed at regular intervals to ascertain details of subsequent revisions. Overall revision rates and revisions for aseptic loosening, wear, and osteolysis were compared across twenty-two tibial implant designs using Cox proportional hazards regression models adjusting for age, sex, calendar year, and body mass index. RESULTS: In comparison with metal-backed modular implants, all-polyethylene tibial components had a significantly lower risk of revision (hazard ratio, 0.3; 95% confidence intervals: 0.2, 0.5 [p < 0.0001]). The risk reduction with all-polyethylene tibial components was not affected by age, sex, or body mass index. With metal-backed modular tibial designs, cruciate-retaining knees performed better than the posterior-stabilized knees (p = 0.002), but this finding was limited to one specific metal-backed modular tibial component, the Press Fit Condylar design. With all-polyethylene tibial components, there was no survivorship difference between cruciate-retaining and posterior-stabilized designs. CONCLUSIONS: All-polyethylene tibial components were associated with better outcomes than metal-backed modular components. Cruciate-retaining and posterior-stabilized designs performed equally well, except with the Press Fit Condylar design. Obese patients may have superior results with all-polyethylene and posterior-stabilized components. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The effect of obesity on direct medical costs in total knee arthroplasty.

BACKGROUND: Obesity prevalence continues to rise in the United States. We sought to examine the effect of obesity on length of hospital stay and direct medical costs in a large cohort of patients who underwent total knee arthroplasty. METHODS: The study included 8129 patients who had undergone 6475 primary total knee arthroplasties and 1654 revision total knee arthroplasties at a large U.S. medical center from January 1, 2000, to September 30, 2008. Patients with bilateral procedures within ninety days following the index admission were excluded. Data on clinical and surgical characteristics and complications were obtained from the original medical records and the institutional joint registry. Patients were classified into eight groups based on their body mass index at the time of surgery. Direct medical costs were calculated in 2010 U.S. dollars by using standardized, inflation-adjusted costs for services and procedures billed during hospitalization and the ninety-day window. Study end points were hospital length of stay and direct medical costs. End points were compared across the eight body mass index categories in both unadjusted and multivariable risk-adjusted analyses. Linear regression models were used to determine the cost impact associated with increasing body mass index and obesity accounting for comorbidities and complications. RESULTS: Body mass index data were available for 99.5% of patients and ranged from 15 to 73 kg/m2. Length of stay and the direct medical costs were lowest for patients with body mass index values in the normal to overweight range. Increasing body mass index was associated with significantly longer hospital stays and costs. Every 5-unit increase in body mass index beyond 30 kg/m2 was associated with approximately $250 to $300 higher hospitalization costs in primary total knee arthroplasty and $600 to $650 higher hospitalization costs in revision total knee arthroplasty. These estimates persisted after adjusting for comorbidities or complications. CONCLUSIONS: Obesity is associated with longer hospital stays and higher costs in total knee arthroplasty. The effect of obesity on costs appears to be independent of obesity-related comorbid conditions and complications.