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1.  Do pessimists report worse outcomes after total hip arthroplasty? 
Background
Seligman’s theory of causal attribution predicts that patients with a pessimistic explanatory style will have less favorable health outcomes. We investigated this hypothesis using self-reported hip pain and hip function 2- years after total hip arthroplasty (THA).
Methods
Most THA patients had completed the Minnesota Multiphasic Personality Inventory (MMPI) during their usual clinical care long before THA (median, 14.7 to 16.6 years). Scores from the MMPI Optimism-Pessimism (PSM) scale were used to categorize patients as pessimistic (t-score >60) or non-pessimistic (t score ≤60). Outcomes were self-reported: (a) moderate-severe pain, (b) absence of “much better” improvement compared to preoperative hip function, and (c) moderate-severe activity limitation. Multivariable logistic regression was adjusted for gender, age and other covariates. Odds ratios (OR) with 95 % confidence intervals (CI) are presented.
Results
We identified 507 patients with 565 primary THAs with an MMPI prior to primary THA, of whom 441 patients with 488 primary THAs had responded to hip pain and function follow-up surveys at 2-years post-surgery. Similarly, 202 patients with 235 revision THAs had an MMPI prior to surgery, of whom 172 patients with 196 revision THAs completed 2-year surveys. Among those with primary THA, pessimists reported (a) a non-significant trend toward more moderate-severe pain at 2-years with OR (95 % CI; p-value), 2.16 (0.90, 5.20; p = 0.08; reference, none-mild pain),; (b) no significant difference for absence of “much better” improvement in hip function at 2-years, 1.87 (0.77, 4.52; p = 0.16; reference, much better hip function); and (c) significantly higher rate of moderate-severe activity limitation at 2-years, 2.90 (1.25, 6.70; p = 0.01). Among revision THA cohort, pessimists reported no significant differences from non-pessimists in moderate-severe pain, improvement in hip function or moderate-severe functional limitation at 2-years.
Conclusions
A pessimistic explanatory style was associated with moderate-severe activity limitation and a non-significant trend towards moderate-severe pain post-THA.
doi:10.1186/s12891-016-1045-4
PMCID: PMC4857442  PMID: 27146803
Pessimism; Total hip arthroplasty; THA; Outcomes; Psychological risk factor; Pessimistic style
2.  Morbid Obesity: Increased Risk of Failure After Aseptic Revision TKA 
Background
Patients with obesity are known to have a higher risk of complications after primary TKA; however, there is a paucity of data regarding the effects of obesity with revision TKAs.
Questions/purposes
We asked the following questions : (1) Are patients with morbid obesity (BMI ≥ 40 kg/m2) at greater risk for repeat revision, reoperation, or periprosthetic joint infection (PJI) compared with patients without obesity (BMI < 30 kg/m2) after an index revision TKA performed for aseptic reasons? (2) Do patients who are not obese achieve higher Knee Society pain and function scores after revision TKA for aseptic reasons?
Methods
We used a retrospective cohort study with 1:1 matching for sex, age (± 3 years) and date of surgery (± 1 year) to compare patients with morbid obesity with patients without obesity with respect to repeat revision, reoperation, and PJI. Using our institution’s total joint registry, we identified 1291 index both-component (femoral and tibial) aseptic revision TKAs performed during a 15-year period (1992–2007). Of these, 120 revisions were in patients with morbid obesity (BMI ≥ 40 kg/m2) and 624 were in patients with a BMI less than 30 kg/m2. We then considered only patients with a minimum 5-year followup, which was available for 77% of patients with morbid obesity and 76% of patients with a BMI less than 30 kg/m2 (p = 0.84). All patients with morbid obesity who met criteria were included (morbid obesity group: n = 93; average followup, 7.9 years) and compared with a matched cohort of patients with a BMI less than 30 kg/m2 (nonmorbid obesity group: n = 93; average followup, 7.3 years). Medical records were reviewed to gather details regarding complications and clinical outcomes.
Results
Overall, patients with morbid obesity had an increased risk of repeat revision (hazard ratio [HR], 3.8; 95% CI, 1.2–16.5; p < 0.02), reoperation (HR, 2.9; 95% CI, 1.3–7.4; p < 0.02), and PJI (HR, 6.4; 95% CI, 1.2–119.7; p < 0.03). Implant survival rates were 96% (95% CI, 92%–100%) and 100% at 5 years, and 81% (95% CI, 70%–92%) and 93% (95% CI, 86%–100%) at 10 years for the patients with morbid obesity and those without morbid obesity, respectively (p = 0.02). At 10 years, The Knee Society pain (90 [95% CI, 88–92] vs 76 [95% CI, 71–81]; p < 0.01) and function (61 [95% CI, 53–69] vs 57 [95% CI, 42–52]; p < 0.01) scores were higher in patients with a BMI less than 30 kg/m2 compared with patients with morbid obesity.
Conclusion
Morbid obesity is associated with increased rates of rerevision, reoperation, and PJI after aseptic revision TKA. As the time-sensitive nature of revision surgery may not always allow for patient or comorbidity optimization, these results emphasize the need for improving our care of patients with morbid obesity earlier on during the osteoarthritic process. Additional studies are needed to risk stratify patients in the morbidly obese population to better guide patient selection and effective optimization.
Level of Evidence
Level III, therapeutic study.
doi:10.1007/s11999-015-4283-0
PMCID: PMC4488195  PMID: 25845948
3.  Multi-Disciplinary Antimicrobial Strategies for Improving Orthopaedic Implants to Prevent Prosthetic Joint Infections in Hip and Knee 
Like any foreign object, orthopaedic implants are susceptible to infection when introduced into the human body. Without additional preventative measures, the absolute number of annual prosthetic joint infections will continue to rise, and may exceed the capacity of health care systems in the near future. Bacteria are difficult to eradicate from synovial joints due to their exceptionally diverse taxonomy, complex mechanistic attachment capabilities, and tendency to evolve antibiotic resistance. When a primary orthopaedic implant fails from prosthetic joint infection, surgeons are generally challenged by limited options for intervention. In this review, we highlight the etiology and taxonomic groupings of bacteria known to cause prosthetic joint infections, and examine their key mechanisms of attachment. We propose that antimicrobial strategies should focus on the most harmful bacteria taxa within the context of occurrence, taxonomic diversity, adhesion mechanisms, and implant design. Patient-specific identification of organisms that cause prosthetic joint infections will permit assessment of their biological vulnerabilities. The latter can be targeted using a range of antimicrobial techniques that exploit different colonization mechanisms including implant surface attachment, biofilm formation, and/or hematogenous recruitment. We anticipate that customized strategies for each patient, joint, and prosthetic component will be most effective at reducing prosthetic joint infections, including those caused by antibiotic-resistant and polymicrobial bacteria.
doi:10.1002/jor.23068
PMCID: PMC4824296  PMID: 26449208
infection; joint; arthroplasty; implant; individualized medicine
4.  Biological Strategies for Improved Osseointegration and Osteoinduction of Porous Metal Orthopedic Implants 
The biological interface between an orthopedic implant and the surrounding host tissue may have a dramatic effect upon clinical outcome. Desired effects include bony ingrowth (osseointegration), stimulation of osteogenesis (osteoinduction), increased vascularization, and improved mechanical stability. Implant loosening, fibrous encapsulation, corrosion, infection, and inflammation, as well as physical mismatch may have deleterious clinical effects. This is particularly true of implants used in the reconstruction of load-bearing synovial joints such as the knee, hip, and the shoulder. The surfaces of orthopedic implants have evolved from solid-smooth to roughened-coarse and most recently, to porous in an effort to create a three-dimensional architecture for bone apposition and osseointegration. Total joint surgeries are increasingly performed in younger individuals with a longer life expectancy, and therefore, the postimplantation lifespan of devices must increase commensurately. This review discusses advancements in biomaterials science and cell-based therapies that may further improve orthopedic success rates. We focus on material and biological properties of orthopedic implants fabricated from porous metal and highlight some relevant developments in stem-cell research. We posit that the ideal primary and revision orthopedic load-bearing metal implants are highly porous and may be chemically modified to induce stem cell growth and osteogenic differentiation, while minimizing inflammation and infection. We conclude that integration of new biological, chemical, and mechanical methods is likely to yield more effective strategies to control and modify the implant–bone interface and thereby improve long-term clinical outcomes.
doi:10.1089/ten.teb.2014.0333
PMCID: PMC4390115  PMID: 25348836
5.  Increased Risk of Periprosthetic Femur Fractures Associated With a Unique Cementless Stem Design 
Background
Postoperative periprosthetic femur fractures are an increasing concern after primary total hip arthroplasty (THA). Identifying and understanding predisposing factors are important to mitigating future risk. Femoral stem design may be one such factor.
Questions/purposes
The goals of our study were to compare the (1) frequency of periprosthetic femur fracture and implant survivorship; (2) time to fracture in those patients who experienced periprosthetic femur fracture; and (3) predictive risk factors for periprosthetic femur fracture between a unique stem design with an exaggerated proximal taper angle and other contemporary cementless, proximally fixed, tapered stems.
Methods
We reviewed all hips in which a femoral hip component with a uniquely exaggerated proximal taper angle (ProxiLock) was implanted during primary THA at a single academic institution. That group of patients was compared with a cohort of patients who underwent primary THA during the same time interval (1995–2008) in which any other cementless, proximally fixed, tapered stem design was used. The two groups differed somewhat in terms of sex, age, and body mass index, although these differences were of unclear clinical significance. During the study, 3964 primary THAs were performed using six different designs of cementless, proximally fixed, tapered femoral hip prostheses. There were 736 stems in the ProxiLock (PL) patient group and 3228 stems in the non-ProxiLock (non-PL) group. In general, the stem highlighted in this study became the routine cementless stem used for primary THA for three arthroplasty surgeons without specific patient or radiographic indications. Periprosthetic fractures were identified within each group. The incidence, timing, type, and treatment required for each fracture were analyzed. The Kaplan-Meier method was used to determine study patient survival free of any postoperative fracture. Radiographs and the electronic medical record of each patient who sustained a fracture were reviewed. Followup was comparable between groups at all time points.
Results
The Kaplan-Meier estimate for fracture-free patient survival was worse in the PL group at all time points with survival of 98.4% (range, 97.4%–99.3%), 97.1% (range, 95.9%–98.3%), 95.4% (range, 93.8%–97.0%), and 92.6% (range, 89.6%–95.3%) at 30 days, 1 year, 5 years, and 10 years, respectively, for the PL patient group compared with 99.8% (range, 99.7%–99.9%), 99.6% (range, 99.3%–99.8%), 99.3% (range, 99.0%–99.6%), and 98.4% (range, 97.5%–99.1%) in the non-PL patient group (p < 0.001). Patients in the PL group had increased cumulative probability of both early and late fractures with cumulative probabilities of fracture of 2.5% (range, 1.3%–3.6%) at 90 days and 7.4% (range, 4.7%–10.4%) at 10 years compared with probabilities of 0.3% (range, 0.1%–0.5%) at 90 days and 1.6% (range, 0.8%–2.5%) at 10 years in the non-PL group (p < 0.001). Patients in the PL group had an increased risk of postoperative periprosthetic femur fracture (hazard ratio [HR], 5.6; 95% confidence interval [CI], 3.4–9.1; p < 0.001); fracture requiring reoperation (HR, 8.4; 95% CI, 4.4–15.9); p < 0.001); and fracture requiring stem revision (HR, 9.1; 95% CI, 4.5–18.5; p < 0.001). Age older than 60 years was also a risk factor for fracture (HR, 3.7; 95% CI, 2.1–6.4), but sex, body mass index, and preoperative diagnosis were not predictive.
Conclusions
Hips implanted with an uncemented femoral stem, which has a uniquely exaggerated proximal taper angle, had an increased risk of both early and late postoperative periprosthetic femur fracture. The majority of patients with a fracture underwent reoperation or stem revision. The unique proximal geometry, lack of axial support from the smooth cylindrical distal stem as well as resorption of the hydroxyapatite coating and poor ongrowth with subsequent subsidence may contribute to increased risk of fracture. Although this particular stem has recently been discontinued by the manufacturer, these findings are important in regard to followup care for patients with this stem implanted as well as for future cementless stem design in general.
Level of Evidence
Level III, therapeutic study.
doi:10.1007/s11999-014-4077-9
PMCID: PMC4419010  PMID: 25502478
6.  Porous Metal Acetabular Components Have a Low Rate of Mechanical Failure in THA After Operatively Treated Acetabular Fracture 
Background
Total hip arthroplasty (THA) for the treatment of posttraumatic osteoarthritis (OA) after acetabular fracture has been associated with a high likelihood of aseptic loosening, instability, and infection. Porous metal components may help to address the issue of loosening, but there are few data on the use of porous metal acetabular components for posttraumatic OA after acetabular fracture.
Questions/purposes
Using an institutional registry, we aimed to report (1) radiographic evidence of fixation; (2) survivorship free from revision; (3) Harris hip scores; and (4) complications and reoperations after THA with a porous metal acetabular component for posttraumatic OA in patients previously treated with open reduction and internal fixation (ORIF) of a displaced acetabular fracture.
Methods
Thirty primary THAs were performed with a porous metal acetabular component for the treatment of posttraumatic OA after ORIF of an acetabular fracture from 1999 through 2010; of these, 28 (93%) were available for followup at a minimum of 2 years. During that same time, 51 primary THAs were performed using other acetabular designs in patients who had previously undergone ORIF of the acetabulum. During the period in question, the general indications for use of porous metal in this setting included compromised acetabular bone stock or quality to the extent that the treating surgeon believed primary fixation with a titanium shell and screws may have been difficult to achieve. Mean age at the time of arthroplasty was 45 years (range, 23–75 years). Median time from ORIF to THA and from THA to last followup was 107 months (range, 4 months to 42 years) and 60 months (range, 25 months to 10 years), respectively. Radiographs were reviewed for this specific study to evaluate the components for evidence of osteointegration. Survivorship free from revision, hip scores, and complications were extracted from our institutional database and electronic medical record.
Results
No acetabular or femoral components were revised for aseptic loosening. Five-year survival with revision for any reason as the endpoint was 88% (95% confidence interval, 0.70–0.96). Harris hip scores improved from a median of 39 preoperatively (range, 3–87) to 82 at last followup (range, 21–100; p < 0.01). Three hips (11%) underwent resection for infection and all three had been treated with staged arthroplasty for concern of infection. Two patients (7%) experienced at least one dislocation postoperatively.
Conclusions
The short-term results of the use of porous metal acetabular components in THA for treatment of posttraumatic OA after acetabular fracture demonstrate low rates of mechanical failure. Although infection and instability remain major concerns in patients with this diagnosis seemingly regardless of the implant design used, porous metal components appear to offer a high likelihood of osseointegration in this clinical setting.
Level of Evidence
Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-014-3852-y
PMCID: PMC4294918  PMID: 25106802
7.  Validation of the Mayo Hip Score: construct validity, reliability and responsiveness to change 
Background
Previous studies have provided the initial evidence for construct validity and test-retest reliability of the Mayo Hip Score. Instruments used for Total Hip Arthroplasty (THA) outcomes assessment should be valid, reliable and responsive to change. Our main objective was to examine the responsiveness to change, association with subsequent revision and the construct validity of the Mayo hip score.
Methods
Discriminant ability was assessed by calculating effect size (ES), standardized response mean (SRM) and Guyatt’s responsiveness index (GRI). Minimal clinically important difference (MCII) and moderate improvement thresholds were calculated. We assessed construct validity by examining association of scores with preoperative patient characteristics and correlation with Harris hip score, and assessed association of scores with the risk of subsequent revision.
Results
Five thousand three hundred seven provided baseline data; of those with baseline data, 2,278 and 2,089 (39 %) provided 2- and 5-year data, respectively. Large ES, SRM and GRI ranging 2.66–2.78, 2.42–2.61 and 1.67–1.88 were noted for Mayo hip scores with THA, respectively. The MCII and moderate improvement thresholds were 22.4–22.7 and 39.4–40.5 respectively. Hazard ratios of revision surgery were higher with lower final score or less improvement in Mayo hip score at 2-years and borderline significant/non-significant at 5-years, respectively: (1) score ≤55 with hazard ratios of 2.24 (95 % CI, 1.45, 3.46; p = 0.0003) and 1.70 (95 % CI, 1.00, 2.92; p = 0.05) of implant revision subsequently, compared to 72-80 points; (2) no improvement or worsening score with hazard ratios 3.94 (95 % CI, 1.50, 10.30; p = 0.005) and 2.72 (95 % CI, 0.85,8.70; p = 0.09), compared to improvement >50-points. Mayo hip score had significant positive correlation with younger age, male gender, lower BMI, lower ASA class and lower Deyo-Charlson index (p ≤ 0.003 for each) and with Harris hip scores (p < 0.001).
Conclusions
Mayo Hip Score is valid, sensitive to change and associated with future risk of revision surgery in patients with primary THA.
Electronic supplementary material
The online version of this article (doi:10.1186/s12891-016-0868-3) contains supplementary material, which is available to authorized users.
doi:10.1186/s12891-016-0868-3
PMCID: PMC4719668  PMID: 26785640
Validation; Mayo hip score; Mayo hip questionnaire; Total hip arthroplasty; Total hip replacement; Validity; Responsiveness; Minimal clinically meaningful difference; MCID; Revision risk; Reliability
8.  The Mark Coventry Award 
Background
Although highly porous metals have demonstrated excellent bone ingrowth properties and so are an intriguing option for fixation in total knee arthroplasty (TKA), some surgeons are skeptical about the durability of uncemented tibial fixation and the potential for soft tissues to adhere to these porous metals and perhaps cause knee stiffness or pain.
Questions/purposes
The purpose of this study was to compare, in the context of a randomized clinical trial, a highly porous metal tibia compared with a traditional modular cemented tibia in terms of survivorship, Knee Society scores, range of motion (ROM), and complications.
Methods
From 2003 to 2006, 397 patients (age 67.8 ± 8.7 years; 54% female) were randomized to three groups: (1) traditional modular cemented tibia; (2) cemented highly porous metal tibia; and (3) uncemented highly porous metal tibia. The same posterior-stabilized femoral component and patella component were cemented in every case. Stratified randomization was done for surgeon, patient’s age, sex, and body mass index. Survivorship at 5 years was compared between the groups, as were Knee Society scores, ROM, and complications. Radiographic assessment included alignment, radiolucency, and implant migration/loosening. Patients were followed until death, revision, or for a minimum of 2 years (mean, 5 years; range, 2–9 years). Four patients were lost to followup before 2 years.
Results
Highly porous metal tibias (both uncemented and cemented) were no different from traditional cemented modular tibial modular components in terms of survivorship at 5 years using a intention-to-treat analysis (96.8% [1]; 97.6% [2]; 96.7% [3]; p = 0.59). A per-protocol analysis revealed that no highly porous metal tibia was revised for aseptic loosening. Highly porous metal tibias performed comparably to traditional cemented modular tibias in terms of Knee Society scores, ROM, and the frequency of complications.
Conclusions
At 5 years this randomized clinical trial demonstrated that highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with a traditional cemented modular tibia in TKA.
Level of Evidence
Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-014-3585-y
PMCID: PMC4390908  PMID: 24687433
9.  Current tobacco use is associated with higher rates of implant revision and deep infection after total hip or knee arthroplasty: a prospective cohort study 
BMC Medicine  2015;13:283.
Background
Tobacco smoking is a risk factor for several adverse post-operative outcomes. We aimed to compare the rates of complications in current tobacco users and non-users who underwent primary total hip arthroplasty (THA) or total knee arthroplasty (TKA).
Methods
All patients who underwent primary THA or TKA at the Mayo Clinic from 2010–2013 were included in the study. Current tobacco use was defined as the use of cigarettes, cigars, pipes, or smokeless tobacco reported at the time of index THA or TKA; current non-users were former users or never users. We used Cox proportional hazards regression to assess the association of current tobacco use status with each post-THA/TKA complication, using hazard ratios and 95 % confidence intervals (CI).
Results
Tobacco use status was available for 7926 patients (95 %) and not available for 446 patients (5 %); 565 (7 %) were current tobacco users. Compared to non-users, current tobacco users  were more likely to be male (p < 0.001), and less likely to be obese (p ≤ 0.008), be older than 60 years, have Charlson score >0 or have undergone TKA rather than THA (p < 0.001 each). The hazard ratios for deep infection (2.37; 95 % CI 1.19, 4.72; p = 0.01) and implant revision (1.78; 95 % CI 1.01, 3.13; p = 0.04) were higher in current tobacco users than in non-users. No significant differences were noted for periprosthetic fractures or superficial infections.
Conclusions
We noted that current tobacco use was associated with high risk of deep infection and implant revision after primary THA or TKA. Future studies should determine the optimal time for tobacco use cessation before elective surgeries such as THA and TKA to improve short-term and long-term arthroplasty outcomes.
doi:10.1186/s12916-015-0523-0
PMCID: PMC4653911  PMID: 26586019
Arthroplasty; Complications; Outcomes; Smoker; Smoking; THA; THR; TKA; TKR; Tobacco use; Total hip replacement; Total knee replacement
10.  Predictors of pain medication use for arthroplasty pain after revision total knee arthroplasty 
Rheumatology (Oxford, England)  2014;53(10):1752-1758.
Objective. Our objective was to study the use of pain medications for persistent knee pain and their predictors after revision total knee arthroplasty (TKA).
Methods. We examined whether demographic (gender, age) and clinical characteristics [BMI, co-morbidity measured by the Deyo–Charlson index (a 5-point increase), anxiety and depression] predict the use of NSAIDs and narcotic pain medications 2 and 5 years after revision TKA. Multivariable logistic regression adjusted for these predictors as well as operative diagnosis, American Society of Anesthesiologists class and distance from the medical centre.
Results. A total of 1533 patients responded to the 2-year questionnaire and 881 responded to the 5-year questionnaire. NSAID use was reported by 13.4% (206/1533) of patients at 2 years and 16.7% (147/881) at 5 years. Narcotic medication use was reported by 5.4% (83/1533) of patients at 2 years and 5.9% (52/881) at 5 years. Significant predictors of the use of NSAIDs for index TKA pain at 2 and 5 years were age >60–70 years [odds ratio (OR) 0.62 (95% CI 0.39, 0.98) and 0.46 (0.25, 0.85)] compared with age ≤60 years and a higher Deyo–Charlson index [OR 0.51 (95% CI 0.28, 0.93)] per 5-point increase at 5-year after revision TKA. Significant predictors of narcotic pain medication use for index TKA pain were age >60–70 years [OR 0.41 (0.21, 0.78)] and >70–80 years [0.40 (95% CI 0.22, 0.73)] at 2 years and depression [OR 4.58 (95% CI 1.58, 13.18)] at 5 years.
Conclusion. Younger age and depression were risk factors for the use of NSAIDs and narcotic pain medications for index TKA pain at 2- and 5-years after revision TKA.
doi:10.1093/rheumatology/ket443
PMCID: PMC4165843  PMID: 24459220
total knee replacement; pain medication; narcotic; NSAIDs; predictors; revision TKA; opioid
11.  Hospital Costs of Total Hip Arthroplasty for Developmental Dysplasia of the Hip 
Background
Developmental dysplasia of the hip (DDH) is a leading cause of total hip arthroplasty (THA) in younger patients. It is unknown how the hospital costs of THA in patients with DDH compare with patients with degenerative arthritis.
Questions/purposes
We undertook this study to determine (1) the hospital cost and length of stay associated with primary THA in patients with dysplasia compared with nondysplastic control subjects; (2) the hospital cost and length of stay of THA in severely dysplastic hips compared with mildly dysplastic hips; and (3) perioperative complications in patients with DDH compared with patients without dysplasia.
Methods
This matched-cohort study included 354 patients undergoing primary THA for DDH and 1029 age-, sex-, and calendar year-matched patients undergoing THA for primary osteoarthritis between 2000 and 2008. DDH severity was measured by the Crowe classification. An institutional database was used to calculate the cost of care. Using line item details (date, type, frequency, and billed charge) for every procedure or service billed at our institution for each patient, bottom-up microcosting valuation techniques were used to generate standardized inflation-adjusted estimates of the cost of each service or procedure in constant dollars. Generalized linear random effects models were used to compare length of stay and costs during hospitalization and the 90-day period after surgery. Query of a longitudinal institutional database was used to identify documented complications.
Results
Patients with DDH undergoing primary THA incurred higher hospital costs than patients with primary osteoarthritis (USD 16,949 versus USD 16,485, p = 0.012). Operating room costs (USD 3471 versus USD 3417, p = 0.0085) and implant costs (USD 3896 versus USD 3493, p < 0.001) were higher in the DDH group compared with the osteoarthritis group. Length of stay was not different between the two groups (4 versus 4 days, p = 0.46). Crowe 4 hips had higher hospital costs than Crowe 1 hips (USD 21,246 versus USD 16,345, p < 0.001) with an associated longer length of stay (5 days versus 4 days, p = 0.0011) and higher implant costs (USD 4380 versus USD 3788, p = 0.0012). There was no detectible difference in 90-day complications in the case group compared with patients undergoing THA for osteoarthritis.
Conclusions
Hospital cost of primary THA is approximately USD 450 higher in patients with DDH compared with osteoarthritis. Increased severity of dysplasia (Crowe classification) was associated with higher costs.
Level of Evidence
Level IV, economic and decision analyses. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-014-3587-9
PMCID: PMC4048391  PMID: 24723141
12.  Obesity Increases Length of Stay and Direct Medical Costs in Total Hip Arthroplasty 
Background
The number of obese patients undergoing THA is increasing. Previous studies have shown that obesity is associated with an increased likelihood of complications after THA, but there is little information regarding the impact of obesity on medical resource use and direct medical costs in THA.
Questions/purposes
We sought to examine the relationship between obesity, length of stay, and direct medical costs in a large cohort of patients undergoing THAs.
Methods
The study included 8973 patients who had undergone 6410 primary and 2563 revision THAs at a large US medical center between January 1, 2000, and September 31, 2008. Patients with bilateral procedures within 90 days after index admission and patients with acute trauma were excluded. Data regarding clinical, 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 BMI at the time of surgery. Direct medical costs were calculated by using standardized, inflation-adjusted costs for services and procedures billed during hospitalization and the 90-day window. Study end points were hospital length of stay, direct medical costs during hospitalization, and the 90-day window. End points were compared across the eight BMI categories in multivariable risk-adjusted linear regression models.
Results
Mean length of stay and the direct medical costs were lowest for patients with a BMI of 25 to 35 kg/m2. Increasing BMI was associated with longer hospital stays and costs. Every five-unit increase in BMI beyond 30 kg/m2 was associated with approximately USD $500 higher hospital costs and USD $900 higher 90-day costs in primary THA (p = 0.0001), which corresponded to 5% higher costs. The cost increase associated with BMI was greater in the revision THA cohort where every five-unit increase in BMI beyond 30 kg/m2 was associated with approximately USD $800 higher hospital costs and USD $1500 higher 90-day costs. These estimates remained unchanged after adjusting for comorbidities or complications.
Conclusions
Obesity is associated with longer hospital stays and higher costs in THA. The significant effect of obesity on costs persists even among patients without comorbidities but the increased costs associated with obesity may be balanced by the potential benefits of THA in the obese. Increasing prevalence of obesity likely contributes to the increasing financial burden of THA worldwide.
Level of Evidence
Level IV, economic and decision analyses. See the Instructions for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-013-3316-9
PMCID: PMC3940745  PMID: 24101527
13.  Cerebrovascular Disease Is Associated with Outcomes after Total Knee Arthroplasty: A U.S. Total Joint Registry Study 
The Journal of arthroplasty  2013;29(1):10.1016/j.arth.2013.04.003.
We assessed the association of cerebrovascular disease with patient-reported outcomes (PROs) of moderate-severe activity limitation and moderate-severe pain at 2- and 5-years after primary total knee arthroplasty (TKA) using multivariable-adjusted logistic regression. 7,139 primary and 4,234 revision TKAs were included. Compared to the patients without cerebrovascular disease, those with cerebrovascular disease had a higher odds ratio (OR) of moderate-severe limitation at 2-years and 5-years, 1.32 (95% confidence interval [CI]: 1.02, 1.72; P=0.04) and 1.83 (95% CI: 1.32, 2.55; P<0.001). No significant associations were noted with moderate-severe pain at 2-years or 5-years. In conclusion, we found that cerebrovascular disease is independently associated with pain and function outcomes after primary TKA. This should be taken into consideration when discussing expected outcomes of TKA with patients.
doi:10.1016/j.arth.2013.04.003
PMCID: PMC3783649  PMID: 23664282
Pain; Activity limitation; cerebrovascular disease; Total knee replacement; arthroplasty; joint replacement; outcomes; Patient-Reported Outcomes; Activities of Daily Living; ADLs; Function; functional limitation
14.  Uncemented Porous Tantalum Acetabular Components: Early Follow-Up and Failures in 599 Revision Total Hip Arthroplasties 
The Iowa Orthopaedic Journal  2015;35:108-113.
Background
The purpose of this study was to determine the early outcomes of 599 cases of revision THA performed using a porous tantalum cup.
Methods
Clinical and radiographic data was sought in all patients at a minimum two years follow-up, after acetabular revision performed with a porous tantalum cup.
Results
Of the 599 cases identified, there were 51 re-operations in 47 patients (7.8 percent). Cup removal was required in 14 of these cases (2.3 percent). The most common cause for cup removal was a septic joint (12). No cups were revised for aseptic loosening during the study period. There was one case of early cup migration. There were 17 incomplete lucencies not initially seen on post-operative films, but identified later, all were non-progressive on subsequent x-rays.
Conclusions
Early results of porous tantalum acetabular components in the revision setting demonstrate good initial stability and low re-operation rates at two years follow-up.
Level of Evidence
Level 4: Case series
PMCID: PMC4492128  PMID: 26361451
15.  Are outcomes after total knee arthroplasty worsening over time? A time-trends study of activity limitation and pain outcomes 
Background
To examine whether function and pain outcomes of patients undergoing primary total knee arthroplasty (TKA) are changing over time.
Methods
The Mayo Clinic Total Joint Registry provided data for time-trends in preoperative and 2-year post-operative activity limitation and pain in primary TKA patients from 1993-2005. We used chi-square test and analysis for variance, as appropriate. Multivariable-adjusted analyses were done using logistic regression.
Results
In a cohort of 7,229 patients who underwent primary TKA during 1993-2005, mean age was 68.4 years (standard deviation (SD), 9.8), mean BMI was 31.1 (SD, 6.0) and 55% were women. Crude estimates showed that preoperative moderate-severe overall limitation were seen in 7.3% fewer patients and preoperative moderate-severe pain in 2.7% more patients in 2002-05, compared to 1992-95 (p < 0.001 for both). At 2-years, crude estimates indicated that compared to 1992-95, moderate-severe post-TKA overall limitation was seen in 4.7% more patients and moderate-severe post-TKA pain in 3.6% more patients in 2002-05, both statistically significant (p ≤ 0.018) and clinically meaningful. In multivariable-adjusted analyses that adjusted for age, sex, anxiety, depression, Deyo-Charlson index, body mass index and preoperative pain/limitation, patients had worse outcomes 2-year post-TKA in 2002-2005 compared to 1993-95 with an odds ratio (95% confidence interval (CI); p-value) of 1.34 (95% CI: 1.02, 1.76, p = 0.037) for moderate-severe activity limitation and 1.79 (95% CI: 1.17, 2.75, p = 0.007) for moderate-severe pain.
Conclusion
Patient-reported function and pain outcomes after primary TKA have worsened over the study period 1993-95 to 2002-05. This time-trend is independent of changes in preoperative pain/limitation and certain patient characteristics.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2474-15-440) contains supplementary material, which is available to authorized users.
doi:10.1186/1471-2474-15-440
PMCID: PMC4301928  PMID: 25519240
Total knee replacement; Time trends; Arthroplasty; Joint replacement; Pain; Function
16.  Increasing obesity and comorbidity in patients undergoing primary total hip arthroplasty in the U.S.: A 13-year study of time trends 
Background
Few, if any data are available are available regarding the time-trends in characteristics of patients who have undergone primary THA. Our objective was to examine the time-trends in key demographic and clinical characteristics of patients undergoing primary total hip arthroplasty (THA).
Methods
We used the data from the Mayo Clinic Total Joint Registry from 1993–2005 to examine the time-trends in demographics (age, body mass index (BMI)), medical (Deyo-Charlson index) and psychological comorbidity (anxiety, depression) and underlying diagnosis of patients undergoing primary THA. Chi-square test and analysis for variance were used. Multivariable-adjusted logistic regression (age, sex, comorbidity-adjusted) compared 1993–95 to other study periods. Odds ratio (OR) and 95% confidence interval (CI) are presented.
Results
The primary THA cohort consisted of 6,168 patients with 52% women. In unadjusted analyses, compared to 1993–95, significantly more patients (by >2-times for most) in 2002–05 had: BMI ≥ 40, 2.3% vs. 6.3%; depression, 4.1% vs. 9.8%; and anxiety, 3.4% vs. 5.7%; and significantly fewer had an underlying diagnosis of rheumatoid/inflammatory arthritis, 3.7% vs. 1.5% (p ≤ 0.01 for all). In multivariable-adjusted models, compared to 1993–95, significantly more patients in 2003–05 had (all p-values ≤ 0.01): BMI ≥ 40, OR, 2.79 (95% CI: 1.85, 4.22); Deyo-Charlson Index ≥ 3, 1.32 (1.07, 1.63); depression, 2.25 (1.66, 3.05); and anxiety, 1.71 (1.19, 2.15). Respectively, fewer patients had a diagnosis of RA/inflammatory arthritis: 0.28 (0.17, 0.46; p < 0.01). Over the 13-year study period, Deyo-Charlson index increased by 22% (0.9 to 1.1) and the mean age decreased by 0.7 years (65.0 to 64.3) (p < 0.01 for both).
Conclusions
Obesity, medical and psychological comorbidity increased and the underlying diagnosis of RA/inflammatory arthritis decreased rapidly in primary THA patients over 13-years. Our cohort characteristics are similar to previously described characteristics of national U.S. cohort, suggesting that these trends may be national rather than local trends. This is important information for policy makers to take into account for resource allocation. Studies of THA outcomes and utilization should take these rapidly changing patient characteristics into account.
doi:10.1186/1471-2474-15-441
PMCID: PMC4302153  PMID: 25519434
Total hip replacement; Time trends; Arthroplasty; Joint replacement; Diagnosis; Obesity; Comorbidity; Osteoarthritis
17.  Clinically important body weight gain following knee arthroplasty: A five-year comparative cohort study 
Arthritis care & research  2013;65(5):669-677.
Objective
The impact of knee arthroplasty on subsequent body weight gain has not been fully explored. Clinically important weight gain following knee arthroplasty would pose potentially important health risks.
Methods
We used one of the largest US-based knee arthroplasty registries and a population- based control sample from the same geographic region to determine whether knee arthroplasty increases risk of clinically important weight gain of 5% or more of baseline body weight over a 5-year postoperative period.
Results
Of the persons in the knee arthroplasty sample, 30.0% gained 5% or more of baseline body weight five years following surgery as compared to 19.7% of the control sample. The multivariable adjusted (age, sex, BMI, education, comorbidity and pre-surgical weight change) odds ratio was 1.6 (95% CI, 1.2, 2.2) in persons with knee arthroplasty as compared to the control sample. Additional arthroplasty procedures during the 5-year follow-up further increased risk for weight gain (OR=2.1, 95% CI, 1.4, 3.1) relative to the control sample. Specifically among patients with knee arthroplasty, younger patients and those who lost greater amounts of weight in the 5-year pre-operative period were at greater risk for clinically important weight gain.
Conclusions
Patients who undergo knee arthroplasty are at increased risk of clinically important weight gain following surgery. Future research should develop weight loss/maintenance interventions particularly for younger patients who have lost a substantial amount of weight prior to surgery as they are most at risk for substantial postsurgical weight gain.
doi:10.1002/acr.21880
PMCID: PMC4169302  PMID: 23203539
18.  Clinically important body weight gain following total hip arthroplasty: A cohort study with five-year follow-up 
Objective
Literature examining the effects of total hip arthroplasty (THA) on subsequent body weight gain is inconclusive. Determining the extent to which clinically relevant weight gain occurs following THA has important public health implications.
Design
We used multivariable logistic regression to compare data from one of the largest US-based THA registries to a population-based control sample from the same geographic region. We also identified factors that increased risk of clinically important weight gain specifically among persons undergoing THA. The outcome measure of interest was weight gain of ≥ 5% of body weight up to 5 years following surgery.
Results
The multivariable adjusted (age, sex, BMI, education, comorbidity and pre-surgical weight change) odds ratio for important weight gain was 1.7 (95% CI, 1.06, 2.6) for a person with THA as compared the control sample. Additional arthroplasty procedures during the 5-year follow-up further increased odds for important weight gain (OR=2.0, 95% CI, 1.4, 2.7) relative to the control sample. A patient with THA had increased risk of important post-surgical weight gain of 12% (OR=1.12; 95%CI,1.08, 1.16) for every kilogram of pre-operative weight loss.
Conclusions
While findings should be interpreted with caution because of missing follow-up weight data, patients with THA appear to be at increased risk of clinically important weight gain following surgery as compared to peers. Patients less than 60 years and who have lost a substantial amount of weight prior to surgery appear to be at particularly high risk of important postsurgical weight gain.
doi:10.1016/j.joca.2012.09.010
PMCID: PMC4169300  PMID: 23047011
knee; hip; arthroplasty; obesity
19.  Time trends in the Characteristics of Patients Undergoing Primary Total Knee Arthroplasty 
Arthritis care & research  2014;66(6):897-906.
Objective
To study the time-trends in socio-demographic and clinical characteristics of patients undergoing primary total knee arthroplasty (TKA).
Methods
We used the Mayo Clinic Total Joint Registry to examine the time-trends in patient demographics (body mass index [BMI], age), underlying diagnosis, medical (Deyo-Charlson index) and psychological comorbidity (anxiety, depression) and examination findings of primary TKA patients from 1993–2005. We used chi-square test and analysis of variance.
Results
7,229 patients constituted the primary TKA cohort; 55% were women. The mean age decreased by 1.3 years (69.3 to 68.0), BMI increased by 1.7 kg/m2 (30.1 to 31.8) and Deyo-Charlson index increased by 36% (1.1 to 1.5) over the 13-year study period (p<0.001 for all). Compared to 1993–95, significantly more patients (by 2–3 times) in 2002–05 had (p<0.001 for all): BMI ≥40, 4.8% vs. 10.6%; age <50, 2.9% vs. 5.2%; Deyo-Charlson index of ≥3, 12% vs. 22.3%; depression, 4.1% vs. 14.8%; anxiety, 4.1% vs. 8.9%; and a significantly fewer had an underlying diagnosis of rheumatoid/inflammatory arthritis, 6.4% vs. 1.5%. Compared to 1993–95, significant reductions were noted in 2002–05 for the physical examination findings of (p<0.001 for all): knee joint effusion, anterior-posterior knee instability, medial-lateral knee instability, moderate-severe knee synovitis, severe limp, fair or poor muscle strength and absent peripheral pulses.
Conclusions
In this large U.S. total joint registry study, we found significant time-trends in patient characteristics, diagnosis, comorbidity and knee/limb examination findings in primary TKA patients over 13-years. These secular trends should be taken into account when comparing outcomes over time and in policy-making decisions.
doi:10.1002/acr.22233
PMCID: PMC4151514  PMID: 24249702
Total knee replacement; time trends; arthroplasty; joint replacement; diagnosis; obesity; comorbidity; osteoarthritis
20.  Medical Comorbidity is Associated with Persistent Index Hip Pain after Primary THA 
Pain medicine (Malden, Mass.)  2013;14(8):10.1111/pme.12153.
Objective
To characterize whether medical comorbidity predicts persistent moderate-severe pain after total hip arthroplasty (THA)
Methods
We analyzed the prospectively collected data from the Mayo Clinic Total Joint Registry for patients who underwent primary or revision THA between 1993–2005. Using multivariable-adjusted logistic regression analyses, we examined whether certain medical comorbidities were associated with persistent moderate-severe hip pain 2- or 5-years after primary or revision THA. Odds ratios (OR), along with 95% confidence intervals (CI) and p-value are presented.
Results
The primary THA cohort consisted of 5,707 THAs and 3,289 THAs at 2- and 5-years, and revision THA, 2,687 and 1,627 THAs, respectively. In multivariable-adjusted logistic regression models, in the primary THA cohort, renal disease was associated with lower odds of moderate-severe hip pain (OR, 0.6; 95% CI, 0.3, 1.0) at 2-years. None of the comorbidities were significantly associated at 5-years. In the revision THA cohort, heart disease was significantly associated with higher risk (OR, 1.7; 95% CI, 1.1, 2.6) at 2-years and connective tissue disease with lower risk (OR, 0.5; 95% CI, 0.3, 0.9) of moderate-severe hip pain at 5-years follow-up.
Conclusion
This study identified new correlates of moderate-severe hip pain after primary or revision THA, a much-feared outcome of hip arthroplasty. Patients with these comorbidities should be informed regarding the increased risk or moderate-severe index hip pain, so that they can have a fully informed consent and realistic expectations.
doi:10.1111/pme.12153
PMCID: PMC3814009  PMID: 23742141
Pain; Function; functional limitation; Total hip replacement; primary; arthroplasty; joint replacement; outcomes; Patient-Reported Outcomes
21.  Patient-level clinically meaningful improvements in activities of daily living and pain after total hip arthroplasty: data from a large US institutional registry 
Rheumatology (Oxford, England)  2013;52(6):1109-1118.
Objective. To characterize patient-level clinically meaningful improvements in pain and limitation of key activities of daily living (ADLs) after primary or revision total hip arthroplasty (THA).
Methods. We analysed prospectively collected data from the Mayo Clinic Total Joint Registry to study clinically meaningful improvements in index hip pain severity and limitation in seven key ADLs (walking, climbing stairs, putting on shoes/socks, picking up objects, getting in/out of car, rising from a chair and sitting), from preoperative to 2- and 5-year post-THA.
Results. The primary THA cohort consisted of 6168 responders preoperatively, 5707 at 2 years and 3289 at 5 years postoperatively. The revision THA cohort consisted of 2063 responders preoperatively, 2682 at 2 years and 1627 at 5 years postoperatively. In the primary THA cohort, clinically meaningful pain reduction to mild or no hip pain at 2 years was reported by 94% with moderate and 91% with severe preoperative pain; respective proportions were 91% and 89% at 5-year follow-up. For revision THA, respective proportions were 84% and 77% at 2 years and 80% and 78% at 5 years. In the primary THA cohort, up to 4% with moderate and 17% with severe preoperative ADL limitation reported severe limitation in the respective activity 2 years post-primary THA; at 5 years, the respective proportions were up to 7% and 20%. Respective proportions for revision THA were up to 10% and 26% at 2 years and 13% and 30% at 5 years.
Conclusions. These comprehensive data for patient-level clinically meaningful improvements in pain and seven key ADLs can help patients set realistic goals for improvement after THA.
doi:10.1093/rheumatology/kes416
PMCID: PMC3651614  PMID: 23382362
pain; activity limitation; activities of daily living; function; functional limitation; total hip replacement; arthroplasty; joint replacement; outcomes; patient-reported outcomes; primary; revision
22.  Better Functional and Similar Pain Outcomes in Osteoarthritis compared to Rheumatoid arthritis after primary total knee arthroplasty: A cohort study 
Arthritis care & research  2013;65(12):10.1002/acr.22090.
Objective
To determine the association of the underlying diagnosis with limitation in activities of daily living (ADLs) and pain in patients undergoing primary total knee arthroplasty (TKA).
Methods
Prospectively collected data from the Mayo Clinic Total Joint Registry were used to assess the association of diagnosis with moderate-severe limitation in activities of daily living (ADLs) and moderate-severe pain and at 2- and 5-years after primary TKA using multivariable-adjusted logistic regression analyses. We calculated odds ratios (OR) and 95% confidence intervals (CI).
Results
There were 7,139 primary TKAs at 2-years and 4,234 at 5-years. In multivariable-adjusted analyses, compared to rheumatoid arthritis (RA)/inflammatory arthritis, osteoarthritis (OA) was associated with significantly lower odds ratio (OR) [95% confidence interval (CI)] of moderate-severe ADL limitation with OR of 0.5 [95% CI: 0.3, 0.8] (p=0.004) at 2-years, and 0.5 [95% CI, 0.3, 0.9] (p=0.02) at 5-years. There was no significant association of diagnosis of OA with moderate-severe pain at 2-years with OR of 1.2 [0.5, 2.7] (p=0.68) or at 5-years with OR of 1.0 [0.3, 3.7] (p=1.0).
Conclusion
We found patients with OA who underwent primary TKA had better ADL outcomes compared to patients with RA/inflammatory arthritis at 2- and 5-years. On the other hand, the pain outcomes did not differ in OA vs. RA after primary TKA. This suggests discordant effect of underlying diagnosis on pain and function outcomes after TKA. These novel findings can be used to better inform both patients and surgeons about expected pain and function outcomes after primary TKA.
doi:10.1002/acr.22090
PMCID: PMC3855298  PMID: 23925956
Total knee replacement; arthroplasty; joint replacement; patient-reported outcomes; osteoarthritis; rheumatoid arthritis
23.  Medical and psychological comorbidity predicts poor pain outcomes after total knee arthroplasty 
Rheumatology (Oxford, England)  2013;52(5):916-923.
Objective. To study comorbidity correlates of moderate to severe pain after total knee arthroplasty (TKA).
Methods. We analysed prospectively collected Total Joint Registry data to examine whether medical (heart disease, peripheral vascular disease, renal disease, chronic obstructive pulmonary disease, diabetes and CTD) and psychological (anxiety and depression) comorbidity is associated with moderate to severe pain after primary or revision TKA. Multivariable-adjusted logistic regression simultaneously adjusted for all comorbidities, age, sex, BMI, underlying diagnosis, American Society of Anesthesiologist (ASA) class, distance from medical centre and implant fixation (only for primary TKA) was used to analyse primary and revision TKA separately.
Results. The primary TKA cohort consisted of 7139 and 4234 TKAs (response rates 65% and 57%) and the revision TKA cohort consisted of 1533 and 881 TKAs at 2 and 5 years (response rates 57% and 48%), respectively. In the primary TKA cohort, anxiety was associated with 1.4 higher odds (95% CI 1.0, 2.0) of moderate to severe index knee pain at 2 years; at 5 years, heart disease (OR 1.7; 95% CI 1.1, 2.6), depression (OR 1.7; 95% CI 1.1, 2.5) and anxiety (OR 1.9; 95% CI 1.2, 3.1) were significantly associated with moderate to severe pain. For revision TKA, CTD (OR 0.5; 95% CI 0.2, 0.9) and depression (OR 1.8; 95% CI 1.1, 3.1) were significantly associated with moderate to severe pain.
Conclusion. This study identified medical and psychological comorbidity risk factors for moderate to severe pain after primary and revision TKA. This information can be used to provide realistic outcome expectations for patients before undergoing primary or revision TKA.
doi:10.1093/rheumatology/kes402
PMCID: PMC3630396  PMID: 23325037
pain; function; functional limitation; total knee replacement; primary; arthroplasty; joint replacement; outcomes; patient-reported outcomes
24.  Depression in primary TKA and higher medical comorbidities in revision TKA are associated with suboptimal subjective improvement in knee function 
Background
To characterize whether medical comorbidities, depression and anxiety predict patient-reported functional improvement after total knee arthroplasty (TKA).
Methods
We analyzed the prospectively collected data from the Mayo Clinic Total Joint Registry for patients who underwent primary or revision TKA between 1993–2005. Using multivariable-adjusted logistic regression analyses, we examined whether medical comorbidities, depression and anxiety were associated with patient-reported subjective improvement in knee function 2- or 5-years after primary or revision TKA. Odds ratios (OR), along with 95% confidence intervals (CI) and p-value are presented.
Results
We studied 7,139 primary TKAs at 2- and 4,234 at 5-years; and, 1,533 revision TKAs at 2-years and 881 at 5-years. In multivariable-adjusted analyses, we found that depression was associated with significantly lower odds of 0.5 (95% confidence interval [CI]: 0.3 to 0.9; p = 0.02) of ‘much better’ knee functional status (relative to same or worse status) 2 years after primary TKA. Higher Deyo-Charlson index was significantly associated with lower odds of 0.5 (95% CI: 0.2 to 1.0; p = 0.05) of ‘much better’ knee functional status after revision TKA for every 5-point increase in score.
Conclusions
Depression in primary TKA and higher medical comorbidity in revision TKA cohorts were associated with suboptimal improvement in index knee function. It remains to be seen whether strategies focused at optimization of medical comorbidities and depression pre- and peri-operatively may help to improve TKA outcomes. Study limitations include non-response bias and the use of diagnostic codes, which may be associated with under-diagnosis of conditions.
doi:10.1186/1471-2474-15-127
PMCID: PMC3990241  PMID: 24725511
Total knee arthroplasty; Knee function; Functional limitation; Primary; Arthroplasty; Joint replacement; Outcomes; Patient-reported outcomes
25.  Aseptic Tibial Debonding as a Cause of Early Failure in a Modern Total Knee Arthroplasty Design 
Background
We observed isolated tibial component debonding from the cement in one modern primary TKA design (NexGen LPS 3° tibial tray; Zimmer, Warsaw, IN, USA). This failure mechanism is sparsely reported in the literature.
Questions/Purposes
We (1) assessed survivorship of this tibial tray with special emphasis on debonding; (2) described clinical and radiographic features associated with tibial failure; and (3) compared patient and radiographic features of the failures with a matched cohort.
Methods
A total of 1337 primary TKAs were performed with a cemented NexGen LPS 3° tibial tray over an 11-year period. Twenty-five knees (1.9%) were revised for tibial debonding. BMI and radiographic alignment in the tibial debonding group were compared with a matched control group. Implant survivorship was assessed using tibial debonding as the end point.
Results
Survival free of revision from tibial debonding was 100% at 1 year and 97.8% at 5 years. The tibial failures shared a typical radiographic pattern with debonding at the cement-implant interface and subsidence into varus and flexion. We found no link between limb alignment or individual component alignment and failure because 22 of the 25 failures occurred in well-aligned knees.
Conclusions
Our standardized followup of patients undergoing TKA at routine intervals allowed us to discover a higher rate of revision resulting from tibial debonding. We have discontinued the use of this particular tibial tray for primary TKA and surveillance for patients undergoing TKA continues to be warranted.
Level of Evidence
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2467-4
PMCID: PMC3528903  PMID: 22790529

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