The impact of diabetes status on pain and physical function following total joint arthroplasty for hip and knee osteoarthritis: variation by sex and body mass index.

Few studies have examined diabetes impact on total joint arthroplasty (TJA) outcomes, with variable findings. We investigated the association between diabetes and post-TJA physical function and pain, examining whether diabetes impact differs by sex and BMI. Patient sample completed questionnaires within 3 months prior to hip or knee TJA for osteoarthritis (OA) and 1-year post-surgery. Surgical 'non-response' was defined as < 30% improvement in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and physical function at 1-year. Two adjusted logistic regression models were estimated: (1) excluding, (2) including an interaction between diabetes, sex and BMI. The sample (626 hip, 754 knee) was 54.9% female, had mean BMI of 30.1, 13.0% reported diabetes. In adjusted models excluding an interaction, diabetes was not associated with non-response. However, a significant 3-way interaction (physical function: p = 0.003; pain: p = 0.006) between diabetes, sex, and BMI was found and was associated with non-response: non-response probability increased with increasing BMI in men with diabetes, but decreased with increasing BMI in women in diabetes. Findings suggest uncertainty in diabetes impact may be due to differential impacts by sex and BMI. A simple consideration of diabetes as present vs. absent may not be sufficient, with implications for the large TJA population.

The impact of diabetes on physical and mental health status and patient satisfaction after total hip and knee arthroplasty.

OBJECTIVE: To assess the impact of diabetes on physical and mental health status, as well as patient satisfaction, one-year following knee and hip total joint arthroplasty (TJA) for osteoarthritis (OA). METHODS: Participants were 626 hip and 754 knee TJA patients. Pre-surgery data were collected on socio-demographics and health status. The 12-item Short Form Health Survey (SF-12) was collected pre- and one year post-surgery, and physical (PCS) and mental component (MCS) summary scores computed. One-year patient satisfaction was also recorded. Four regression models tested the effect of diabetes on: 1) PCS change score; 2) MCS change score; 3) achieving minimal clinically important improvement (MCII) on PCS; and 4) patient satisfaction ('Somewhat or Very Satisfied' vs. 'Somewhat or Very Dissatisfied'). An interaction between surgical joint and diabetes was tested in each model. RESULTS: Self-reported diabetes prevalence was 13.0% (95% CI: 11.2%-14.7%) and was more common in knee 16.1% (95% CI: 13.4%-18.7%) than hip 9.3% (95% CI: 7.0%-11.5%) patients. In adjusted analyses, change scores were 2.3 units less on the PCS for those with diabetes compared to those without (p = 0.005). Patients with diabetes were about half as likely to achieve MCII as patients without diabetes (p = 0.004). Diabetes was not significantly associated with satisfaction or changes in MCS scores. Diabetes effects did not differ by surgical joint. CONCLUSIONS: Findings support that diabetes has a negative impact on improvements in physical health after TJA. Considering the growing prevalence of OA and diabetes in the population, our findings support the importance of perioperative screening and management of diabetes in patients undergoing TJA.

Identification of a differential metabolite-based signature in patients with late-stage knee osteoarthritis.

Objective: Multiple disease phenotypes have been identified in knee osteoarthritis (OA) patients based on anthropometric, sociodemographic and clinical factors; however, differential systemic metabolite-based signatures in OA patients are not well understood. We sought to identify differential plasma metabolome signatures in a cross-sectional sample of late-stage knee OA patients. Methods: Plasma from 214 (56.5% female; mean age â€‹= â€‹67.58 years) non-diabetic, non-obese (BMI <30 â€‹kg/m2, mean â€‹= â€‹26.25 â€‹kg/m2), radiographic KL 3/4 primary knee OA patients was analyzed by metabolomics. Patients with post-traumatic OA and rheumatoid arthritis were excluded. Hierarchical clustering was used to identify patient clusters based on metabolite levels. A refined metabolite signature differentiating patient clusters was determined based on ≥ 10% difference, significance by FDR-adjusted t-test (q-value < 0.05), and random forests importance score ≥1, and analyzed by AUROC. Bioinformatics analysis was used to identify genes linked to ≥2 annotated metabolites. Associated enriched pathways (q â€‹< â€‹0.05) were determined. Results: Two patient clusters were determined based on the levels of 151 metabolites identified. Metabolite signature refinement found 24 metabolites could accurately predict cluster classification within the sample (AUC â€‹= â€‹0.921). Fifty-six genes were linked to at least 2 â€‹KEGG annotated metabolites. Pathway analysis found 26/56 genes were linked to enriched pathways including tRNA acylation and B-vitamin metabolism. Conclusion: This study demonstrates systemic metabolites can classify a cross-sectional cohort of OA patients into distinct clusters. Links between metabolites, genes and pathways can help determine biological differences between OA patients, potentially improving precision medicine and decision-making.

Identification of prosthetic hip and knee joint infections using administrative databases-A validation study.

OBJECTIVE: To determine whether combinations of diagnosis and procedures codes can improve the detection of prosthetic hip and knee joint infections from administrative databases. DESIGN: We performed a validation study of all readmissions from January 1, 2010, until December 31, 2016, following primary arthroplasty comparing the diagnosis and procedure codes obtained from an administrative database based upon the International Classification of Disease, Tenth Revision (ICD-10) to the reference standard of chart review. SETTING: Four tertiary-care hospitals in Toronto, Canada, from 2010 to 2016. PARTICIPANTS: Individuals who had a primary arthroplasty were identified using procedure codes. INTERVENTION: Chart review of readmissions identified the presence of a prosthetic joint infection and, if present, the surgical procedure performed. RESULTS: Overall, 27,802 primary arthroplasties were performed. Among 8,844 readmissions over a median follow-up of 669 days (interquartile range, 256-1,249 days), a PJI was responsible for or present in 586 of 8,844 (6.6%). Diagnosis codes alone exhibited a sensitivity of 0.88 (95% CI, 0.85-0.92) and positive predictive value (PPV) of 0.78 (95% CI, 0.74-0.82) for detecting a PJI. Combining a PJI diagnosis code with procedure codes for an arthroplasty and the insertion of a peripherally inserted central catheter improved detection: sensitivity was 0.92 (95% CI, 0.88-0.94) and PPV was 0.78 (95% CI, 0.74-0.82). However, procedure codes were unable to identify the specific surgical approach to PJI treatment. CONCLUSIONS: Compared to PJI diagnosis codes, combinations of diagnosis and procedure codes improve the detection of a PJI in administrative databases.

Sex-Modified Effects of Depression, Low Back Pain, and Comorbidities on Pain After Total Knee Arthroplasty for Osteoarthritis.

OBJECTIVE: The influence of sex on post-total knee arthroplasty (TKA) outcomes has been variable in the literature. Though sex is often reported as an averaged effect, we undertook this study to investigate whether sex modified the influence of presurgery characteristics on post-TKA knee pain. METHODS: This was a prospective study with data derived from 477 TKA osteoarthritis patients (279 women, 198 men). Questionnaires were completed presurgery and at 3 months postsurgery. The association between 3-month post-TKA knee pain and presurgery covariates (body mass index, comorbidity count, symptomatic joint count, low back pain, knee pain, and depressive symptoms) was assessed by linear regression. Sex-specific effects were evaluated using interactions. RESULTS: Women had significantly worse presurgery knee pain, joint count, and depressive symptoms, and worse postsurgery knee pain, than men. With simple covariate adjustment, no sex effect on pain was found. However, sex was found to moderate the effects of comorbidities (worse for women [P = 0.013]), presence of low back pain (worse for men [P = 0.003]), and depressive symptoms (worse for men [P < 0.001]) on postsurgery pain. Worse presurgery pain was associated with worse postsurgery pain similarly for women and men. CONCLUSION: The influence of some patient factors on early post-TKA pain cannot be assumed to be the same for women and men; average effects may mask underlying associations. Results suggest a need to consider sex differences in understanding TKA outcomes, which may have important implications for prognostic tool development in TKA.

Factors Associated With Opioid Use in Presurgical Knee, Hip, and Spine Osteoarthritis Patients.

OBJECTIVE: To evaluate rates of prescription opioid use among patients with presurgical knee, hip, and spine osteoarthritis (OA) and associations between use and sociodemographic and health status characteristics. METHODS: Participants were patients with presurgical, end-stage OA of the knee (n = 77), hip (n = 459), and spine (n = 168). Data were collected on current use of opioids and other pain medications, as well as measures of sociodemographic and health status variables and depression and pain (0-10 numeric rating scale). Rates of opioid use were calculated by sex, age, and surgical site. Multivariable logistic regression was used to examine associations between opioid use (sometimes/daily versus never) and other study variables. RESULTS: The mean age of participants was 65.6 years; 55.5% were women, 15% of patients reported "sometimes" using opioids, and 15% reported "daily use." Use of opioids was highest among patients with spine OA (40%) and similar among patients with knee and hip OA (28% and 30%, respectively). Younger women (ages <65 years) reported the greatest use of opioids overall, particularly among patients with spine OA. From multivariable logistic regression, greater likelihood of opioid use was significantly associated with spine OA (versus knee OA), obesity, being a current or former smoker, higher symptomatic joint count, greater depressive symptoms, greater pain, and current use of other prescription pain medication. CONCLUSION: Nearly one-third of patients with presurgical OA used prescription opioid medication. Given the questionable efficacy of opioids in OA and risk of adverse effects, higher opioid use among younger individuals and those with depressive symptoms is of concern and warrants further investigation.

Sex differences in the relationship between individual systemic markers of inflammation and pain in knee osteoarthritis.

Objective: There are suggestions that the relationship between inflammation and pain in osteoarthritis (OA) may differ by sex, yet studies have been limited. We investigated whether the relationship between knee-specific OA pain and systemic inflammatory markers differs by sex. Design: 196 patients scheduled for knee arthroplasty for OA were included. Questionnaires were completed and blood samples drawn pre-surgery. Questionnaire data: knee pain (WOMAC), sex, age, height, weight, comorbidities, depressive symptoms, and symptomatic joint count. Systemic inflammatory markers (cytokines IL-6, IL-8, IL-10, IL-1ß and TNF-α) were measured by multiplex ELISA. A series of regression models with interaction terms between sex and ln-transformed inflammatory markers were estimated with pain score as the outcome. The adjusted relationship between pain and inflammatory markers, by sex, were presented graphically. Results: Mean age was 64 years (range 43-89); females comprised 58.7% of the sample. In adjusted analyses, similar relationships between knee pain and lnIL-10 (negative: ߠ​= â€‹-1.28, 95%CI (-1.97, -0.58)) and lnTNF-α (positive: ߠ​= â€‹0.92, 95%CI (0.11, 1.76)) were found for females and males. In contrast, relationships between knee pain and lnIL-1ß, lnIL-6 and lnIL-8 differed in direction for females and males. Specifically, for lnIL-1ß and lnIL-8 they were positive for males, negative for females. The opposite was found with lnIL-6, negative for males, positive for females. Conclusion: These findings provide some evidence of sex-specific relationships between individual inflammatory markers and knee OA pain. They expose a need for further exploration of sex-differences in this context, with potential future implications for treatment or drug development in OA.

Topical tranexamic acid reduces transfusion rates in simultaneous bilateral total knee arthroplasty: a retrospective case series.

BACKGROUND: Topical tranexamic acid (TA) has been reported to be effective in reducing postoperative bleeding and transfusions after total knee arthroplasty (TKA). The main objective of this study was to retrospectively assess the effectiveness and safety of topical TA administration in patients undergoing simultaneous bilateral TKA. METHODS: We conducted a retrospective chart review of consecutive cohorts of patients undergoing simultaneous bilateral TKA. We compared the patients who received TA with patients from a similar time frame who did not receive TA. For those who received TA, a topical concentration of 2 g per 30 mL of normal saline was used in each knee. Preoperative and postoperative hemoglobin, transfusions, length of stay (LOS) and postoperative complications were recorded for each patient until discharge. Outcome measures were analyzed using independent t test, χ2 test and logistic regression. RESULTS: We included 49 patients in our analysis: 25 who received TA and 24 who did not. There were no statistical differences in demographics between the groups. The rate of transfusion in the TA group was 4% compared with 67% in the non-TA group (p < 0.001). The net hemoglobin loss in the TA group was 4.1 g/dL versus 6.2 g/dL in the non-TA group (p < 0.001). The use of TA was found to be associated with a greater than 99% reduced risk of receiving a transfusion (odds ratio 0.003, 95% confidence interval < 0.001-0.072, p < 0.001). There were no thromboembolic events in patients who received TA, and there was 1 pulmonary embolus in the non-TA group. Postoperative LOS was significantly reduced in the TA group (mean difference 1.1 d, p = 0.005). CONCLUSION: Topical administration of TA in patients undergoing simultaneous bilateral TKA significantly reduced transfusions, blood loss and postoperative LOS, with no increased risk of thromboembolic events.

CONTEXTE: Selon certains rapports, l'acide tranexamique (AT) topique réduirait efficacement les saignements postopératoires et le recours aux transfusions après une intervention pour prothèse totale du genou. Le principal objectif de cette étude était d'évaluer de manière rétrospective l'efficacité et l'innocuité de l'AT topique chez des patients soumis à une intervention pour prothèse totale des 2 genoux. MÉTHODES: Nous avons procédé à une analyse rétrospective des dossiers de cohortes consécutives de patients soumis à une intervention pour prothèse totale des 2 genoux. Nous avons comparé les patients ayant reçu l'AT aux patients d'une période similaire qui n'ont pas reçu l'AT. Pour ceux qui ont reçu l'AT, la concentration topique de 2 g par 30 mL de solution physiologique a été utilisée dans les 2 genoux. On a enregistré chez chaque patient les taux d'hémoglobine pré- et postopératoires, le nombre de transfusions, la durée du séjour hospitalier et les complications postopératoires jusqu'à leur congé. Les paramètres ont été analysés à l'aide du test t, du test du χ2 et de la régression logistique. RÉSULTATS: Nous avons inclus 49 patients dans notre analyse : 25 ayant reçu l'AT et 24 ne l'ayant pas reçu. Il n'y avait aucune différence statistique entre les groupes pour ce qui est des caractéristiques démographiques. Le taux de transfusions dans le groupe ayant reçu l'AT a été de 4 %, contre 67 % dans le groupe n'ayant pas reçu l'AT (p < 0,001). La baisse nette de l'hémoglobine dans le groupe ayant reçu l'AT a été de 4,1 g/dL, contre 6,2 g/dL dans le groupe n'ayant pas reçu l'AT (p < 0,001). L'utilisation de l'AT a été associée à une réduction de plus de 99 % du risque de transfusion (rapport des cotes 0,003, intervalle de confiance de 95 % < 0,001-0,072, p < 0,001). On n'a noté aucun incident thromboembolique chez les patients ayant reçu l'AT, et une embolie pulmonaire dans le groupe n'ayant pas reçu l'AT. La durée du séjour hospitalier postopératoire a été significativement plus brève dans le groupe ayant reçu l'AT (différence moyenne 1,1 j, p = 0,005). CONCLUSION: L'administration topique d'AT chez des patients soumis à une intervention pour prothèse totale des 2 genoux a significativement réduit le recours aux transfusions et les pertes sanguines et a abrégé les séjours hospitaliers postopératoires, sans accroître le risque d'incidents thromboemboliques.

Tranexamic acid for the prevention and management of orthopedic surgical hemorrhage: current evidence.

Total joint arthroplasty can be associated with major blood loss and require subsequent blood transfusions for postoperative anemia. Measures to effectively and safely decrease blood loss and reduce the need for blood transfusions would help improve patient safety and lower health care costs. A possible pharmacological option to reduce surgical blood loss in total joint arthroplasty is the use of tranexamic acid. Abundant literature has shown that intravenous and/or topical administration of tranexamic acid is effective in reducing blood loss and blood transfusions, with no increased risk of venous thromboembolic events or other complications.

Trunnionosis: the latest culprit in adverse reactions to metal debris following hip arthroplasty.

The imaging findings of periprosthetic soft tissue lesions (pseudotumours) have been typically defined in the context of newer second-generation metal-on-metal hip arthroplasty. More recently, similar findings have been described in the setting of non-metal-on-metal prostheses. Although uncommon, wear and corrosion between the metal surfaces at the head-neck ('trunnionosis') and neck-stem interfaces are the potential culprits. With modular junctions containing at least one cobalt chromium component frequently present in hip arthroplasty prostheses, the incidence of this mode of adverse wear may be higher than previously thought (irrespective of the specific bearing couple used). In the present report, we described a case of a severe adverse local tissue reaction secondary to suspected corrosion at the head-neck taper in a metal-on-polyethylene total hip arthroplasty and reviewed the literature. Knowledge of this topical entity should help radiologists facilitate early diagnosis and ensure early management of this potentially serious complication.

Comparative outcomes and cost-utility after surgical treatment of focal lumbar spinal stenosis compared with osteoarthritis of the hip or knee--part 1: long-term change in health-related quality of life.

BACKGROUND CONTEXT: It is well accepted that total hip and knee arthroplasty (THA/TKA) for osteoarthritis (OA) is associated with reliable and sustained improvements in postoperative health-related quality of life (HRQoL). Although several studies have demonstrated comparable outcomes with THA/TKA after surgical intervention for lumbar spinal stenosis (LSS), the sustainability of the outcome after LSS surgery compared with THA/TKA remains uncertain. PURPOSE: The primary purpose of this study is to assess whether improvements in HRQoL after surgical management of focal lumbar spinal stenosis (FLSS) with or without spondylolisthesis are sustainable over the long term compared with that of THA/TKA for OA. STUDY DESIGN: Single-center, retrospective, longitudinal matched cohort study of prospectively collected outcomes, with a minimum of 5-year follow-up (FU). PATIENT SAMPLE: Patients who had primary one- to two-level spinal decompression with or without instrumented fusion for FLSS and THA/TKA for primary OA. OUTCOME MEASURES: Postoperative change from baseline to last FU in Short-Form 36 physical component summary (PCS) and mental component summary (MCS) scores among groups was used as the primary outcome measure. METHODS: An age, sex-matched inception cohort of primary one- to two-level spinal decompression with or without instrumented fusion for FLSS (n=99) was compared with a cohort of primary THA (n=99) and TKA (n=99) for OA and followed for a minimum of 5 years. Linear regression was used for the primary analysis. RESULTS: Mean (percent) FUs in months were 80.5+16.04 (79%), 94.6+16.62 (92%), and 80.6+16.84 (85%) for the FLSS, THA, and TKA cohorts, respectively, with a range of 5 to 10 years for all three cohorts. The number of patients who have undergone revision including those lost to FU for the FLSS, THA, and TKA cohorts were n=20 (20.2%, same site [n=7] and adjacent segment [n=13]) requiring 27 operations, n=3 (3%, same site) requiring 5 operations, and n=8 (8.1%, same site) requiring 12 operations, respectively (p<.01). The average time to first revision was 56/65/43 months, respectively. Mean postoperative PCS (p<.0001) and MCS (p<.02) scores improved significantly and were durable for all groups at the last FU. The mean changes from baseline PCS/MCS scores to last FU were 8.5/6.4, 12.3/7.0, and 8.3/4.9 for FLSS, THA, and TKA, respectively. Adjusting for baseline age, sex, body mass index, PCS score, and MCS score, there was a strong trend in favor of greater sustained change in the PCS score of THA over FLSS (p=.07) and TKA (p=.08). No difference was noted for change in PCS score between FLSS and TKA (p=.95). No differences were noted for change in MCS score among all three cohorts (p>.1). CONCLUSIONS: Significant improvements in HRQoL after surgical treatment of FLSS with or without spondylolisthesis and hip and knee OA are sustained for a mean of 7 to 8 years, with a minimum of 5-year FU. Despite a higher revision rate, patients undergoing surgery for FLSS can expect a comparable long-term average improvement in HRQoL from baseline compared with their peers undergoing TKA and to a lesser extent THA.

Topical tranexamic acid reduces transfusion rates in total hip and knee arthroplasty.

The efficaciousness of topical tranexamic acid use at the end of knee arthroplasty surgery to reduce blood loss and transfusion requirements has previously been shown. The aim of this study was to retrospectively assess the effectiveness of topical tranexamic acid use, comparing 155 patients undergoing hip and knee arthroplasty surgery in which tranexamic acid was routinely used, to a group of 149 patients from a similar time frame prior to the introduction of tranexamic acid use. The transfusion rate fell from 19.3% to 2.3% for hip arthroplasty patients and from 13.1% to 0% for knee arthroplasty patients; these differences were significant. We also found significant reductions in haemoglobin loss, blood loss and length of stay of 8 g/L, 244 mL and 1.0 days respectively for hip arthroplasties and 15 g/L, 527 mL and 1.2 days respectively for knee arthroplasties following the introduction of tranexamic acid.

Comparative outcomes and cost-utility following surgical treatment of focal lumbar spinal stenosis compared with osteoarthritis of the hip or knee: part 2--estimated lifetime incremental cost-utility ratios.

BACKGROUND CONTEXT: Although total hip arthroplasty (THA) and total knee arthroplasty (TKA) have been widely accepted as highly cost-effective procedures, spine surgery for the treatment of degenerative conditions does not share the same perception among stakeholders. In particular, the sustainability of the outcome and cost-effectiveness following lumbar spinal stenosis (LSS) surgery compared with THA/TKA remain uncertain. PURPOSE: The purpose of the study was to estimate the lifetime incremental cost-utility ratios for decompression and decompression with fusion for focal LSS versus THA and TKA for osteoarthritis (OA) from the perspective of the provincial health insurance system (predominantly from the hospital perspective) based on long-term health status data at a median of 5 years after surgical intervention. STUDY DESIGN/SETTING: An incremental cost-utility analysis from a hospital perspective was based on a single-center, retrospective longitudinal matched cohort study of prospectively collected outcomes and retrospectively collected costs. PATIENT SAMPLE: Patients who had undergone primary one- to two-level spinal decompression with or without fusion for focal LSS were compared with a matched cohort of patients who had undergone elective THA or TKA for primary OA. OUTCOME MEASURES: Outcome measures included incremental cost-utility ratio (ICUR) ($/quality adjusted life year [QALY]) determined using perioperative costs (direct and indirect) and Short Form-6D (SF-6D) utility scores converted from the SF-36. METHODS: Patient outcomes were collected using the SF-36 survey preoperatively and annually for a minimum of 5 years. Utility was modeled over the lifetime and QALYs were determined using the median 5-year health status data. The primary outcome measure, cost per QALY gained, was calculated by estimating the mean incremental lifetime costs and QALYs for each diagnosis group after discounting costs and QALYs at 3%. Sensitivity analyses adjusting for +25% primary and revision surgery cost, +25% revision rate, upper and lower confidence interval utility score, variable inpatient rehabilitation rate for THA/TKA, and discounting at 5% were conducted to determine factors affecting the value of each type of surgery. RESULTS: At a median of 5 years (4-7 years), follow-up and revision surgery data was attained for 85%-FLSS, 80%-THA, and 75%-THA of the cohorts. The 5-year ICURs were $21,702/QALY for THA; $28,595/QALY for TKA; $12,271/QALY for spinal decompression; and $35,897/QALY for spinal decompression with fusion. The estimated lifetime ICURs using the median 5-year follow-up data were $5,682/QALY for THA; $6,489/QALY for TKA; $2,994/QALY for spinal decompression; and $10,806/QALY for spinal decompression with fusion. The overall spine (decompression alone and decompression and fusion) ICUR was $5,617/QALY. The estimated best- and worst-case lifetime ICURs varied from $1,126/QALY for the best-case (spinal decompression) to $39,323/QALY for the worst case (spinal decompression with fusion). CONCLUSION: Surgical management of primary OA of the spine, hip, and knee results in durable cost-utility ratios that are well below accepted thresholds for cost-effectiveness. Despite a significantly higher revision rate, the overall surgical management of FLSS for those who have failed medical management results in similar median 5-year and lifetime cost-utility compared with those of THA and TKA for the treatment of OA from the limited perspective of a public health insurance system.

Does a prefabricated gentamicin-impregnated, load-bearing spacer control periprosthetic hip infection?

INTRODUCTION: Treating deep infection following THA has been a challenge. While the standard treatment has remained a two-stage revision, spacer designs, incorporated antibiotics, and concentrations have varied. Since control of infection may relate to choice and concentration of antibiotics, it is important to report rates of control from various spacers. QUESTIONS/PURPOSES: We therefore determined (1) the rate of infection control and (2) complications associated with a prefabricated, load-bearing, gentamicin-impregnated hip spacer in treating periprosthetic infections of the hip. METHODS: We retrospectively reviewed 33 patients with periprosthetic THA infections treated with a prefabricated, partial load-bearing, gentamicin-impregnated hemiarthroplasty spacer. Thirty of the 33 patients underwent second stage reimplantation after a mean 15 weeks. We collected patient demographic data, laboratory values, infecting organism, size of spacer mold, antibiotic selection, complications, and infection control rates from two academic centers. Recurrent infection at last followup was determined by the presence of physical symptoms or signs or elevated serologic tests. The minimum followup was 24 months (mean, 43 months; range, 24-70 months). RESULTS: Twenty-eight of the 30 patients who underwent reimplantation remained infection-free at last followup: one patient became reinfected with a different organism secondary to wound problems; one became reinfected with the same organism, but was restaged with the mold used in this study, reimplanted, and subsequently remained free of infection. Two of the 33 patients had persistently elevated inflammatory markers at the completion of their first stage and were restaged with this mold; both underwent reimplantation and remained free of infection at latest followup. One of the 33 patients was satisfied and ambulatory with their spacer mold. There were no major complications. CONCLUSION: Our data supported the use of a partial load-bearing, gentamicin-impregnated hemiarthroplasty spacer in treating deep periprosthetic THA infections. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Microarray analysis of the infrapatellar fat pad in knee osteoarthritis: relationship with joint inflammation.

OBJECTIVE: To examine differences in genes involved in fat metabolism, energy homeostasis, adipogenesis, and inflammation between endstage and early-stage knee osteoarthritis (OA) infrapatellar fat pads (IFP). METHODS: Twenty-nine endstage and 5 early-stage primary OA IFP were harvested at knee surgery. Total RNA was extracted, labeled, and hybridized to whole-genome expression arrays. Unsupervised analysis of all samples using principal components analysis or 2-way hierarchical clustering showed groupings based on tissue source and disease. Statistical testing identified sets of genes that displayed differences between the 2 fat types. Western blot analysis was performed for protein expression of an identified gene of interest. RESULTS: The 29 IFP demonstrated an elevation in the expression of adipokines such as adiponectin and leptin. A statistically significant increased expression was seen for genes of adipogenesis, such as peroxisome proliferator-activated receptor-γ (PPAR-γ), diacylglycerol acyltransferase 2 (DGAT2), cluster of differentiation (CD36), and thyroid hormone responsive spot (THRSP) in the severe OA fat pads as compared to the controls. A subset of 5 patients in the endstage OA group were consistently similar in gene expression to early OA tissue. Protein expression of PPAR-γ2 was 5.4-fold and PPAR-γ1 was 1.4-fold greater in endstage versus early OA tissue. CONCLUSION: Endstage OA fat pads demonstrated a significant upregulation of genes for fat metabolism and energy homeostasis and a mixed result for inflammatory cytokines.

Predicting the longer-term outcomes of total hip replacement.

OBJECTIVE: The objective of this study was to identify the patient-level predictors (age, sex, body mass index, mental health, and comorbidity) for a sustained functional outcome at a minimum 1 year of followup after total hip replacement (THR). METHODS: We reviewed data from our registry on 636 consecutive patients from 1998 to 2005. Demographic data and the outcome scores of the Western Ontario McMaster University Osteoarthritis Index (WOMAC) and Medical Outcomes Study Short-form 36 (SF-36) scores were extracted from the database. Longitudinal regression modeling was performed to identify the predictive factors of interest. Fourteen percent of patients were missing outcomes data at 1 year of followup. RESULTS: The mean followup in our cohort was 3.3 years (range 1-6 yrs) and there were no revisions for aseptic loosening performed during this time. Mean clinical outcome scores were found to be relatively constant for the 6 years after surgery. Older age, year of followup, and greater comorbidity were identified as negative prognostic factors for a sustained functional outcome following THR (p < 0.05). CONCLUSION: Understanding of longterm surgical outcomes should be appropriately used to set realistic patient expectations of surgery.

Quantifying the pain experience in hip and knee osteoarthritis.

PURPOSE: The present study investigated whether the conceptualization of hip and knee osteoarthritis pain implicit in the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Medical Outcomes Study Short-Form 36 (SF-36) scales is complete, or whether the addition of another scale, such as the Short-Form McGill Pain Questionnaire (MPQ-SF), provides a more complete characterization. Furthermore, the impact that mental health symptoms and catastrophizing had on these scales was investigated. METHODS: Before hip and knee arthroplasty, 200 patients completed surveys of demographic data, the WOMAC pain scale, the MPQ-SF, the SF-36 Bodily Pain scale, the Pain Catastrophizing Scale and the Hospital Anxiety and Depression Scale. Correlations between scales were calculated and linear regression modelling was used to determine the impact of mental health and catastrophizing on these three pain measures. RESULTS: A strong correlation between the WOMAC and SF-36 pain scales (r=-0.70) was found; however, both correlated only moderately with the MPQ-SF (r=0.36 and r=-0.36, respectively). Linear regression modelling showed that the Pain Catastrophizing Scale significantly predicted a greater score on all three pain scales (P<0.05). CONCLUSIONS: The addition of the MPQ-SF appears to add to a more complete quantification of the pain experience in hip and knee osteoarthritis.

Metabolic syndrome and the functional outcomes of hip and knee arthroplasty.

OBJECTIVE: Patients with an elevated systemic inflammatory state are known to report greater pain with knee osteoarthritis (OA). We investigated the influence of risk factors of metabolic syndrome (MetS) on patient function before and after hip and knee replacement surgery. METHODS: A total of 677 consecutive patients with primary knee replacement and 547 consecutive patients with primary hip replacement with at least one MetS risk factor were reviewed from our joint registry. Demographic variables of age, sex, and comorbidity were retrieved. MetS risk factors were defined as body mass index (BMI) > 30 kg/m(2), diabetes, hypertension, and hypercholesterolemia. Baseline and 1-year Western Ontario McMaster University Osteoarthritis Index (WOMAC) scores were compared across patients by number of MetS risk factors, ranging from 1 to 4. Linear regression modeling was used to evaluate the effects of the MetS risk groups and the individual metabolic abnormalities on predicting baseline and 1-year WOMAC scores. Knee and hip patients were reviewed separately. RESULTS: The knee and hip patients showed a significant difference in sex distribution, BMI, and mean comorbidity across risk groups (p < 0.05). Unadjusted analysis showed that baseline and 1-year WOMAC scores, for both knee and hip patients, increased significantly with increasing number of MetS risk factors (p < 0.05). The linear regression model with the individual metabolic abnormalities was found to be more predictive of outcome than one with the number of MetS risk factors. Hypertension and obesity were the metabolic factors most predictive of a poorer outcome following hip surgery as compared to just obesity for knee patients. CONCLUSION: Patient function following joint replacement surgery, particularly hip surgery, is negatively affected by metabolic abnormalities perhaps secondary to the systemic proinflammatory state. This knowledge should be used when counseling patients prior to surgery.

BMI independently predicts younger age at hip and knee replacement.

Obesity has been identified as a risk factor for the development of hip and knee osteoarthritis (OA) and may play a role in exacerbating existing disease. Therefore, we hypothesized that obese patients would present for hip and knee replacement surgery at a younger age than nonobese patients. From our registry, we performed a cross-sectional study of 841 hip and 804 knee replacement patients. Patients were categorized by BMI ≤ 25 kg/m(2), 25.1-29.9 kg/m(2), 30-34.9 kg/m(2), and ≥ 35 kg/m(2). Linear regression modeling was used to examine the relationship between BMI and age at surgery. Hip and knee replacement patients' mean age at surgery was 7.1 and 7.9 years younger, respectively, if their BMI was ≥ 35 kg/m(2) when compared to patients with a BMI ≤ 25 kg/m(2) (P = 0.002). BMI was a significant independent (of gender, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, surgeon, and comorbidity) predictor of age at knee replacement (P < 0.05). WOMAC scores were significantly worse preoperatively in patients with a BMI ≥ 35 kg/m(2) compared to those with a BMI ≤ 25 kg/m(2) (P < 0.05). Our study indicates that obese patients, especially those with a BMI ≥ 35 kg/m(2), presented for and underwent joint replacement surgery at a younger age as compared to nonobese patients.