Clinical Results and Survivorship of the GENESIS II Total Knee Arthroplasty at a Minimum of 15 Years.

BACKGROUND: The purpose of this study was to examine the 15-year survivorship and long-term clinical outcomes of the GENESIS II total knee arthroplasty (TKA). METHODS: Patients who underwent TKA with the GENESIS II system between 1995 and 1999 were retrieved from our institutional database. We report a Kaplan-Meier survival analysis as well as Western Ontario and McMaster Universities Arthritis Index, the Short Form Health Survey-12 (SF-12), and the Knee Society Scores at a mean of 16 years. RESULTS: Four-hundred sixty-nine TKAs were performed with a mean patient age of 68 years. Patients were followed up prospectively for a mean of 16 years (range, 14.8-19.5 years). The Kaplan-Meier survival analysis at 15 years, with revision for any reason as the end point, was 96.4% (95.5%-97.3%). The Western Ontario and McMaster Universities Arthritis Index and the Knee Society Scores were significantly improved (P < .001) from the preoperative period to the latest follow-up. Patients had a significant improvement (P < .001) from the preoperative to the latest follow-up on the Physical Health Composite Score of the SF-12, but no change was noted on the Mental Health Composite Score of the SF-12. CONCLUSION: The unique design features of the GENESIS II TKA system have remained a constant over the duration of its clinical use, a rarity for contemporary TKA systems which are often altered before the publication of long-term results. The GENESIS II continues to demonstrate excellent long-term survivorship and improvements in health-related outcomes at a mean of 15 years, representing the standard for TKA systems at our institution.

The Knee Society Short Form Reduces Respondent Burden in the Assessment of Patient-reported Outcomes.

BACKGROUND: The patient's own evaluation of function and satisfaction is a fundamental component of assessing outcomes after total knee arthroplasty (TKA). The new Knee Society Knee Score was introduced in 2012 and has been shown to be a valid and reliable instrument for measuring the outcome of TKA. This score combines an objective, physician-derived component and a patient-reported component to characterize the expectations, satisfaction, and functional activities of diverse lifestyles of contemporary patients undergoing TKA. However, in the routine clinical setting, the administration and scoring of outcome measures is often resource-intensive, as the expenditure of time and budget for outcome measurement increase with the length and complexity of the instrument used, and so a short-form assessment can help to reduce the burden the assessment of outcomes. QUESTIONS/PURPOSES: The purposes of this study were (1) to develop a short-form version of the new Knee Society Knee Score; (2) to validate the short form against the full Knee Society Knee Score; and (3) to evaluate the responsiveness to treatment (TKA) of the new Knee Society short-form assessment. METHODS: To develop the short form, data from the sample of 497 patients recruited during validation of the original long form the new Knee Society Knee Score were used. The multicenter study was approved by the institutional review boards at 15 participating medical institutions within the United States and Canada. An analytic item reduction approach was applied simultaneously but separately to preoperative and postoperative patient-reported data to select a subset of items from the original form that had good measurement properties and closely reflected the scores obtained using the original form. RESULTS: Expectations and satisfaction were reflected by a single item in the newly developed short form compared with a total of five satisfaction and three expectation items in the long form. The functional activities subscale was reduced from 17 to six items. An excellent correlation was demonstrated between function scores derived from the functional activities subscale of the original long-form score (17 items) and the six-item short form (r = 0.97; p < 0.01). The sample mean difference between the two scores was less than 4 points with a SD of 6.7 points. The short form was capable of discriminating clinically different groups of patients before and after TKA with virtually the same estimated effect size as the original functional activities subscale of the new Knee Society Knee Score. CONCLUSIONS: The Knee Society Knee Score long form is still recommended for research studies and for more sensitive measurement of the outcomes of individual patients. However, for general clinical use with large patient populations, the short form is expected to improve the rate of patient completion while also being easier to administer. In this study, we found the short-form version of the Knee Society Knee Score to be practical, valid, reliable, and responsive for assessing the functional outcome of TKA.

Radiographic Evaluations of Revision Total Knee Arthroplasty: A Plea for Uniform Assessments.

Thorough radiographic evaluation is necessary for perioperative assessments in revision total knee arthroplasty. There has been a large degree of variability in reporting these findings within the peer-reviewed literature. Our purpose was to evaluate studies that radiographically assessed alignment in the coronal and sagittal plane, patella alignment and thickness, presence and characterization of implant interface, and radiolucency. Secondly, we reviewed studies using a standardized reporting system to evaluate radiographic findings (the Knee Society Roentgenographic Evaluation and Scoring System) and the number of times it was referenced. Only 62% of studies evaluated all radiographic parameters, 57% to 91% assessed each metric, and 55% used standardized reporting systems. This emphasizes the need for a uniform evaluation method to ensure consistent radiographic assessment and optimal standard of care.

Development of a Modern Knee Society Radiographic Evaluation System and Methodology for Total Knee Arthroplasty.

To accompany the new clinical Knee Society Score, a committee was formed to develop an updated radiographic assessment and evaluation system. The purpose is to accumulate radiographic data in a standardized manner to facilitate more accurate interpretation, documentation and clinical correlation. We systematically reviewed the TKA radiographic evaluation literature as well as the original Knee Society Radiographic Evaluation and Scoring System. A modern system was developed, approved by the Knee Society membership, which ensured proper radiographic documentation of coronal and sagittal implant alignment, fixation interface integrity with respect to radiolucent lines and osteolysis, and a zonal classification system to document precise deficiency locations. It is hoped that data may be accumulated in a standardized manner with eventual formulation of implant risk "criteria" or "scores'.

Ten-year results comparing posterior cruciate-retaining versus posterior cruciate-substituting total knee arthroplasty.

We compared the 10-year survival rates and clinical outcomes of posterior cruciate-retaining (CR) versus posterior cruciate-substituting (CS) total knee arthroplasty (TKA), using the Genesis II knee system (Smith and Nephew, Memphis, TN). Our institutional database identified patients undergoing a primary knee with the Genesis II system between 1995 and 2000. These patients were followed for an average of 12.3years (range 10.2-14.4years). There were 143 (34.5%) CR and 271 (65.5%) CS implants. No significant difference in 10-year survivorship was noted between the two cohorts. The postoperative clinical scores (KSCRS, WOMAC, SF-12) and knee ROM were significantly better for the CS cohort. In this large, long-term, single-implant prospective study, CS performed better than CR in terms of clinical scores and range of motion.

Joint replacement recipients' views about health information privacy.

BACKGROUND: Researchers are concerned about the possibility of restricted access to data as a result of specific consent requirements in privacy legislation, potentially resulting in smaller samples and a lack of representativeness which could bias results. In addition, there is uncertainty about what influences individuals to give consent for the use of their personal health information. OBJECTIVE: To measure joint replacement recipients' health information privacy views and to assess potential predictors of these views. DESIGN: Cross-sectional survey. SETTING AND PARTICIPANTS: Potential joint replacement recipients from two teaching hospitals in London, Ontario, Canada. MAIN VARIABLES: Age, gender, education, employment status, anticipated joint replacement, and expectations for surgery. MAIN OUTCOME MEASURES: Privacy concerns as measured by the Concern Scale. RESULTS: The response rate was 182/253 or 72%. The mean Concern score was 143.9/235.0 for the total sample (range = 82-216). Women had higher levels of privacy concerns than men on slightly over half of the individual questionnaire items. In women, surgical joint, age and employment explained 15% of the variance in concerns about personal health information privacy (P = 0.001). The model explained 6% of the variance in concerns in men (P = 0.138) and was not statistically significant. DISCUSSION AND CONCLUSION: This study indicates that demographic characteristics and health-care experiences play a role in the variability of health information privacy concerns. A greater understanding of patients' privacy views about health information could lead to a greater harmonization among privacy rules, research and data access, and the preferences of health-care consumers.

Feasibility, effectiveness and costs associated with a web-based follow-up assessment following total joint arthroplasty.

The purpose of this study was to assess the feasibility, effectiveness and costs of a web-based follow-up compared to in-person assessment following primary total hip or total knee arthroplasty. Patients who were at least 12 months postoperative were randomized to follow-up method. We excluded patients who had revision surgery, osteolysis, complications or identified radiographic issues. 229 patients (118 Web, 111 in-person) completed the study. There were no patients who had an issue missed by the web-based follow-up. Patients in the web-based group travelled less (28.2km vs 103.7km, (P<0.01)), had lower associated costs ($10.45 vs $21.36, (P<0.01)) and took less time to complete (121.7min web vs 228.7min usual). Web-based follow-up is a feasible, clinically effective alternative with lower associated costs than in-person clinic assessment.

The fate of the remaining knee(s) or hip(s) in osteoarthritic patients undergoing a primary TKA or THA.

The purpose of this study was to determine the fate of the remaining hip(s) and knee(s) following an initial total hip or knee arthroplasty in 5352 patients with idiopathic osteoarthritis who were followed for a minimum ten years (mean 17.8 ± 5.7 years). Following an initial primary TKA, 46.0% of patients had a contralateral TKA, 2.3% had an ipsilateral THA and 1.3% had a contralateral THA. Following an initial primary THA, 30.5% of patients had a contralateral THA, 6.8% had an ipsilateral TKA and 2.9% had a contralateral TKA. Cox regression analysis demonstrated that BMI was the sole risk factor for a second THA, but both age less than sixty years and a higher BMI were significant factors for patients requiring an additional primary TKA.

A randomized trial comparing acetabular component fixation of two porous ingrowth surfaces using RSA.

Several new porous ingrowth surfaces for acetabular component fixation have recently been developed. The purpose of this study was to compare the in vivo fixation achieved by two different porosity ingrowth surfaces using radiostereometric analysis (RSA). Sixty-two patients undergoing primary total hip arthroplasty (THA) were randomized to receive a cementless acetabular component with either a 61% high porosity asymmetric titanium porous surface (StikTite, Smith and Nephew, TN, USA) or a 45% low porosity sintered bead porous surface (Roughcoat, Smith and Nephew, TN, USA). RSA and clinical follow-up examinations were done post-operatively, 6-weeks, 3-months, 6-months, 1-year and 2-years. Both the high porosity StikTite and lower porosity Roughcoat surfaces provided excellent biologic fixation.

Measurement of joint kinematics using a conventional clinical single-perspective flat-panel radiography system.

PURPOSE: The ability to accurately measure joint kinematics is an important tool in studying both normal joint function and pathologies associated with injury and disease. The purpose of this study is to evaluate the efficacy, accuracy, precision, and clinical safety of measuring 3D joint motion using a conventional flat-panel radiography system prior to its application in an in vivo study. METHODS: An automated, image-based tracking algorithm was implemented to measure the three-dimensional pose of a sparse object from a two-dimensional radiographic projection. The algorithm was tested to determine its efficiency and failure rate, defined as the number of image frames where automated tracking failed, or required user intervention. The accuracy and precision of measuring three-dimensional motion were assessed using a robotic controlled, tibiofemoral knee phantom programmed to mimic a subject with a total knee replacement performing a stair ascent activity. Accuracy was assessed by comparing the measurements of the single-plane radiographic tracking technique to those of an optical tracking system, and quantified by the measurement discrepancy between the two systems using the Bland-Altman technique. Precision was assessed through a series of repeated measurements of the tibiofemoral kinematics, and was quantified using the across-trial deviations of the repeated kinematic measurements. The safety of the imaging procedure was assessed by measuring the effective dose of ionizing radiation associated with the x-ray exposures, and analyzing its relative risk to a human subject. RESULTS: The automated tracking algorithm displayed a failure rate of 2% and achieved an average computational throughput of 8 image frames/s. Mean differences between the radiographic and optical measurements for translations and rotations were less than 0.08 mm and 0.07° in-plane, and 0.24 mm and 0.6° out-of-plane. The repeatability of kinematics measurements performed using the radiographic tracking technique was better than ±0.09 mm and 0.12° in-plane, and ±0.70 mm and ±0.07° out-of-plane. The effective dose associated with the imaging protocol used was 15 µSv for 10 s of radiographic cine acquisition. CONCLUSIONS: This study demonstrates the ability to accurately measure knee-joint kinematics using a single-plane radiographic measurement technique. The measurement technique can be easily implemented at most clinical centers equipped with a modern-day radiographic x-ray system. The dose of ionizing radiation associated with the image acquisition represents a minimal risk to any subjects undergoing the examination.

Twenty-three-year outcome of the porous coated anatomic total hip replacement: a concise follow-up of a previous report.

We previously reported the ten to fourteen-year results for 311 Porous Coated Anatomic total hip replacements that had been inserted by two surgeons in 279 patients. The purpose of the present report is to update that study and to report the outcome beyond twenty years. The patients were followed prospectively with clinical assessment with use of the Harris hip score and radiographic analysis, and the results were collected in a database. Two hundred and sixty-eight hips were functioning at the time of death or at the time of the latest follow-up. A total of forty-three hips (14%) underwent major revision for all causes, and an additional four hips underwent minor revision. At a mean of twenty-three years of follow-up, Kaplan-Meier analysis revealed a survival rate of 83% with revision for any reason as the end point. The survival rate was 95% for the femoral component and 88% for the acetabular component with revision for any reason as the end point. The rate of survival of the acetabular component was significantly higher in hips with a 26-mm femoral head than in those with a 32-mm femoral head (91% compared with 80%; p = 0.026).

The minimum 10-year results of a second-generation cementless acetabular shell with a polished inner surface.

The purpose of this prospective study was to evaluate the minimum 10-year outcomes and survivorship of the Reflection shell with a polished inner surface and an improved locking mechanism. Three hundred sixty-three total hip replacements with a mean follow-up of 11.6 years (range, 10.0-15.1) were evaluated. The mean Harris Hip and WOMAC scores at last follow-up were 87 and 77, respectively. Four cups were revised: 2 for infection and 2 for aseptic loosening. Thirteen cases underwent liner exchange for wear. Radiographic review of remaining cups identified 8.8% with identifiable peri-acetabular osteolysis and no cases of loosening. The overall 10- and 15-year Kaplan-Meier survivorship was 94% and 90% for the total hip arthroplasty system while the survivorship of the shell remained 99.4% at 15 years.

Retrieval analysis of modular total knee replacements: factors influencing backside surface damage.

Retrieved knee implants were examined to investigate the influence of patient and implant related factors on backside damage. Fifty-two implants of three different models were examined that all had cemented tibial trays without screw holes. A semi-quantitative grading system supplied backside damage scores (BDS) for each polyethylene (PE) tibial insert. Evidence was obtained to support the use of a constraining partial-peripheral locking mechanism and polished tibial tray surface (particularly for male patients) to reduce backside damage. Overall, male patients in the present study were associated with higher body mass and higher BDS compared with female patients. Furthermore, PE inserts sterilized by gamma-in-air had higher BDS than PE inserts sterilized in inert environments (gas-plasma or ethylene-oxide). Also, the proximal surfaces of tibial trays that had been grit-blasted showed embedded particles that may have increased backside damage. While none of these overall findings was unexpected, the present study provided detailed supporting analysis based on data from clinical retrievals, which may further support the use of a polished tibial tray combined with partial-peripheral locking mechanism to reduce BDS.

Results of cemented femoral revisions for periprosthetic femoral fractures in the elderly.

The treatment goals of Vancouver type B2 periprosthetic femoral fractures in elderly patients with a limited life expectancy are early weight bearing without compromising the fracture healing. Thirty-one patients with a mean age of 82 years were treated with a long cemented stem with additional allograft or plate fixation, followed by immediate full weight bearing. Seven major complications occurred within the first 3 months postoperatively. Forty-three percent of patients had died within the first year with their implant in place. Sixteen patients had survived more than 1 year. None of the implants had to be revised at a mean follow-up of 46 months. The results of this series suggest that this technique can provide acceptable results and offers the advantages of reduced cost and early weight bearing.

How do CAD models compare with reverse engineered manufactured components for use in wear analysis?

BACKGROUND: To accurately quantify polyethylene wear in retrieved arthroplasty components, the original geometry of the component must be estimated accurately using a reference geometry such as a computer-aided design (CAD) model or a never-implanted insert. However, differences may exist between the CAD model and manufactured inserts resulting from manufacturing tolerances. QUESTIONS/PURPOSES: We quantified the deviations between CAD models and newly manufactured inserts and determined how these deviations compared with using a never-implanted insert as a reference geometry. METHODS: We obtained five cruciate-retaining (CR) and five posterior-stabilizing (PS) tibial inserts and their CAD models. The inserts were scanned and reconstructed using microcomputed tomography (micro-CT). Differences in volume and surface geometry were measured among (1) the individual inserts; (2) between the inserts and a CAD model; and (3) between the inserts and a reference geometry constructed from multiple scanned inserts averaged together. RESULTS: The micro-CT volumes were, on average, 0.4% smaller (34-178 mm(3)) than the CAD model volumes. The mean deviation between the CAD model and insert surface geometry was 25.7 µm smaller for CR and 36.8 µm smaller for PS. The mean deviation between the inserts and an averaged reference geometry was 1.4 µm larger for CR and 0.4 µm smaller for PS. CONCLUSIONS: Deviations exist between manufactured tibial inserts and CAD models that could cause errors in wear measurements. Scanned inserts may better represent the preimplantation geometry of worn inserts than CAD models, depending on the manufacturing variability between lots. CLINICAL RELEVANCE: The magnitude of the error in estimation of the preimplantation geometry of a retrieved component could add or subtract the equivalent of 1 year of wear.

Development of a new Knee Society scoring system.

BACKGROUND: The Knee Society Clinical Rating System was developed in 1989 and has been widely adopted. However, with the increased demand for TKA, there is a need for a new, validated scoring system to better characterize the expectations, satisfaction, and physical activities of the younger, more diverse population of TKA patients. QUESTIONS/PURPOSES: We developed and validated a new Knee Society Scoring System. METHODS: We developed the new knee scoring system in two stages. Initially, a comprehensive survey of activities was developed and administered to 101 unilateral TKA patients (53 women, 48 men). A prototype knee scoring instrument was developed from the responses to the survey and administered to 497 patients (204 men, 293 women; 243 postoperatively, 254 preoperatively) at 15 medical institutions within the United States and Canada. Objective and subjective data were analyzed using standard statistical and psychometric procedures and compared to the Knee Injury and Osteoarthritis Score and SF-12 scores for validation. Based on this analysis, minor modifications led to the new Knee Society Scoring System. RESULTS: We found the new Knee Society Scoring System to be broadly applicable and to accurately characterize patient outcomes after TKA. Statistical analysis confirmed the internal consistency, construct and convergent validity, and reliability of the separate subscale measures. CONCLUSIONS: The new Knee Society Scoring System is a validated instrument based on surgeon- and patient-generated data, adapted to the diverse lifestyles and activities of contemporary patients with TKA. This assessment tool allows surgeons to appreciate differences in the priorities of individual patients and the interplay among function, expectation, symptoms, and satisfaction after TKA.

Comparison of total hip arthroplasty performed with and without cement: a randomized trial. A concise follow-up, at twenty years, of previous reports.

Total hip arthroplasty has been associated with excellent implant survival rates, but debate remains concerning the best fixation method for the components. A randomized controlled trial, which included 250 patients (mean age, sixty-four years) with osteoarthritis who were managed with total hip arthroplasty between October 1987 and January 1992, was conducted to compare the results of fixation with and without cement. Patients were followed for a mean of twenty years (range, seventeen to twenty-one years). Kaplan-Meier survivorship analysis at twenty years revealed significantly lower survival rates for cemented implants as compared with cementless implants. The cementless tapered stem had an extremely good survival rate of 99%. Radiographs showed evidence of mild stress-shielding around 95% of the cemented stems and 88% of the cementless stems; stress-shielding of grade 3 or greater was seen around the remaining 12% of the cementless stems.

Posterior condyle surface damage on retrieved femoral knee components.

Twenty-two retrieved femoral knee components were identified with posterior condyle surface damage on average at 99° flexion (range, 43°-135° flexion). Titanium alloy material transfer and abrasive surface damage were evident on cobalt-chromium alloy femoral components that were in contact with titanium alloy tibial trays. Surface damage on the retrieved Oxinium femoral components (Smith and Nephew, Inc, Memphis, Tenn) that were in contact with titanium alloy tibial trays showed gouging, associated with the removal and cracking of the oxide and exposure of the zirconium-niobium alloy substrate. Cobalt-chromium alloy femoral components that were in contact with cobalt-chromium alloy tibial trays showed abrasive wear. Contact between the femoral component and tibial tray should be avoided to prevent surface damage to the femoral condyles, which could potentially accelerate polyethylene wear in vivo.