Number Of Total Knee Replacements Research Articles

Clinical differences between periprosthetic and native distal femur fractures: a comparative observational study

IntroductionThe incidence of periprosthetic distal femur fractures (PDFF) is increasing as the number of total knee replacements becomes more common. This study compared the demographics, fracture characteristics, treatment, and outcomes of periprosthetic versus native distal femur fractures (NDFF).Materials and methodsThis was a retrospective cohort study of patients ≥ 18 who underwent surgical fixation of NDFF or PDFF from 2012 to 2020 at a level-1 trauma center. The main variables collected included demographics, AO/OTA fracture classification, fixation construct, concomitant fractures, polytrauma rates, bone density, and reduction quality. Primary outcomes were unexpected return to the operating room (UROR), hospital length of stay, and quality of reduction. T-tests, Fisher’s exact tests, and multivariate analyses were used for statistical analysis.Results209 patients were identified, including 70 PDFF and 139 NDFF. PDFF patients were elderly females (81%) with isolated (80%) and comminuted (85%) 33 A.3 (71%) fractures. NDFF patients included 53% females, were commonly middle-aged, and displayed comminuted (92%) 33 C.2 fractures. 48% of NDFF patients had concomitant fractures. Intramedullary nailing was the primary fixation for both groups, followed by nail-plate combination (37%) for PDFF and lateral locking plates (21%) for NDFF. NDFF patients experienced significantly longer hospital stays, higher UROR rates, and worse quality of reduction (p < 0.05). PDFF patients had a significantly greater prevalence of low bone density (p < 0.05).ConclusionPDFF occur as isolated injuries with significant metaphyseal comminution in elderly females with low bone quality. NDFF commonly occurs in younger patients with less metaphyseal comminution and concomitant fractures. Intramedullary nailing was the most common treatment for both groups, although preference for nail-plate combination fixation is increasing. NDFF type 33 C fractures are at greater risk of UROR.

Musculoskeletal Rehabilitation: New Perspectives in Postoperative Care Following Total Knee Arthroplasty Using an External Motion Sensor and a Smartphone Application for Remote Monitoring.

The number of total knee replacements performed annually is steadily increasing. Parallel options for postoperative care are decreasing, which reduces patient satisfaction. External devices to support physical rehabilitation and health monitoring will improve patient satisfaction and postoperative care. In a prospective, international multicenter study, patients were asked to use an external motion sensor and a smartphone application during the postoperative course of primary total knee arthroplasty. The collected data were transferred to a data platform, allowing for the real-time evaluation of patient data. In three participating centers, 98 patients were included. The general acceptance of using the sensor and app was high, with an overall compliance in study participation rate of up to 76%. The early results showed a significant improvement in the overall quality of life (p < 0.001) and significant reductions in pain (p < 0.01) and depression (p < 0.001). The early results of this clinical and multicenter study emphasize that there is a high interest in and acceptance of digital solutions in patients' treatment pathways. Motion sensor and smartphone applications support patients in early rehabilitation.

Long-term cost-effectiveness of matrix-associated chondrocyte implantation in the German health care system: a discrete event simulation

IntroductionCartilage defects in the knee can be caused by injury, various types of arthritis, or degeneration. As a long-term consequence of cartilage defects, osteoarthritis can develop over time, often leading to the need for a total knee replacement (TKR). The treatment alternatives of chondral defects include, among others, microfracture, and matrix-associated autologous chondrocyte implantation (M-ACI). The purpose of this study was to determine cost-effectiveness of M-ACI in Germany with available mid- and long-term outcome data, with special focus on the avoidance of TKR.Materials and methodsWe developed a discrete-event simulation (DES) that follows up individuals with cartilage defects of the knee over their lifetimes. The DES was conducted with a status-quo scenario in which M-ACI is available and a comparison scenario with no M-ACI available. The model included 10,000 patients with articular cartilage defects. We assumed Weibull distributions for short- and long-term effects for implant failures. Model outcomes were costs, number of TKRs, and quality-adjusted life years (QALYs). All analyses were performed from the perspective of the German statutory health insurance.ResultsThe majority of patients was under 45 years old, with defect sizes between 2 and 7 cm2 (mean: 4.5 cm2); average modeled lifetime was 48 years. In the scenario without M-ACI, 26.4% of patients required a TKR over their lifetime. In the M-ACI scenario, this was the case in only 5.5% of cases. Thus, in the modeled cohort of 10,000 patients, 2700 TKRs, including revisions, could be avoided. Patients treated with M-ACI experienced improved quality of life (22.53 vs. 21.21 QALYs) at higher treatment-related costs (18,589 vs. 14,134 € /patient) compared to those treated without M-ACI, yielding an incremental cost‐effectiveness ratio (ICER) of 3376 € /QALY.ConclusionM-ACI is projected to be a highly cost‐effective treatment for chondral defects of the knee in the German healthcare setting.

Self-Powered Load Sensing Circuitry for Total Knee Replacement.

There has been a significant increase in the number of total knee replacement (TKR) surgeries over the past few years, particularly among active young and elderly people suffering from knee pain. Continuous and optimal monitoring of the load on the knee is highly desirable for designing more reliable knee implants. This paper focuses on designing a smart knee implant consisting of a triboelectric energy harvester and a frontend electronic system to process the harvested signal for monitoring the knee load. The harvester produces an AC signal with peak voltages ranging from 10 V to 150 V at different values of knee cyclic loads. This paper demonstrates the measurement results of a PCB prototype of the frontend electronic system fabricated to verify the functionality and feasibility of the proposed approach for a small range of cycling load. The frontend electronic system consists of a voltage processing unit to attenuate high peak voltages, a rectifier and a regulator to convert the input AC signal into a stabilized DC signal. The DC voltage signal provides biasing for the delta-sigma analog-to-digital converter (ADC). Thus, the output of the triboelectric harvester acts as both the power signal that is rectified/regulated and data signal that is digitized. The power consumption of the proposed PCB design is approximately 5.35 μW. Next, the frontend sensor circuitry is improved to accommodate a wider range of cyclic load. These results demonstrate that triboelectric energy harvesting is a promising technique for self-monitoring the load inside knee implants.

To assess cases of total knee replacement in a tertiary care centre

Background: Total knee arthroplasty has revolutionized the care of patients with end stage arthritic conditions. Increasing life expectancy, growing demand and success of this surgery have lead to signicant increase in the number of total knee replacements. The present study was conducted to assess cases of total knee replacement in a tertiary care centre. Material and Methods: The present retrospective study was conducted in the department of Orthopedics. It comprised of 180 patients of both genders in which TKA was performed. A thorough clinical examination and Radiological assessment was performed. All patients were assessed clinically using the knee society score. Statistical analyses were performed using SPSS 20.0. P value less than 0.05 was considered significant. Results: In the present study total participants were 180 in which 62.22% were male and 37.77% were females. The clinical outcome was excellent in 81.11%, good in 8.33%, fair in 3.88% and poor in 6.66% cases. Conclusion: The present study concluded that maximum cases of total knee replacement were in males and clinical outcome was excellent in maximum cases.

Patient-Reported Outcomes Following Total Knee Replacement in Patients

An increasing number of total knee replacements (TKRs) are being performed in response to the growing burden of osteoarthritis. Patients <65 years of age represent the fastest growing group of TKR recipients and are expected to account for an increasing number of primary and revision procedures. Concerns have been raised about the outcomes that can be expected by this age demographic who are more active, physically demanding, and have longer life expectancies compared to older TKR recipients. This systematic review and meta-analysis evaluated the effectiveness of TKR for osteoarthritis in patients <65 years of age, compared to older individuals. A systematic search of Embase and Medline was conducted to identify studies which examined patient-reported outcomes measured using disease-specific and generic health-related quality of life instruments. Ten studies met our inclusion criteria and were included in this review. These studies comprised 1747 TKRs performed between 1977 and 2014. In the meta-analysis of two prospective studies (288 TKRs), patients <65 years of age were able to attain large and clinically meaningful improvements in pain, function, and quality of life. One of these studies (61 TKRs) suggested that patients <55 years of age attained a larger degree of improvement compared to older individuals. Results into the second postoperative decade were less certain, with some data suggesting a high prevalence of pain and patterns of functional decline. Further research is required to investigate longer-term outcomes following TKR for osteoarthritis in younger patients.

Literature review of the causes of pain following total knee replacement surgery: prosthesis, inflammation and arthrofibrosis

Adverse knee pain occurs in 10–34% of all total knee replacements (TKR), and 20% of TKR patients experience more pain post-operatively than pre-operatively. Knee pain is amongst the top five reasons for knee replacement revision in the United Kingdom. The number of TKRs is predicted to continue increasing due to the ageing population.A narrative literature review was performed on the different causes of pain following TKR. A database search on Scopus, PubMed, and Google Scholar was conducted to look for articles related to TKR, pain, and cause. Articles were selected based on relevance, publication date, quality of research and validation. Relevant sections were added to the review.One hundred and fourteen articles were identified and potential causes of TKR pain included: arthrofibrosis, aseptic loosening, avascular necrosis, central sensitization, component malpositioning, infection, instability, nerve damage, overstuffing, patellar maltracking, polyethylene wear, psychological factors and unresurfaced patella.It is important to tailor our approach to address the individual causes of pain. Certain controllable risk factors can be managed pre-operatively to minimize post-operative pain. Risk factors help to predict adverse pain outcomes and identify specific causes.There are multiple causes of pain following TKR. Some factors will require further extensive studies, and as pain is a commonly attributed reason for TKR revision, its underlying aetiologies should be explored. Understanding these factors helps to develop effective methods for diagnosis, prevention and management of TKR pain, which help to improve patient outcomes.Cite this article: EFORT Open Rev 2020;5:534-543. DOI: 10.1302/2058-5241.5.200031

The use of digitally collected patient-reported outcome measures for newly operated patients with total knee and hip replacements to improve post-treatment recovery: study protocol for a randomized controlled trial

BackgroundThe number of total knee replacements (TKRs) and total hip replacements (THRs) has been increasing noticeably in high-income countries, such as Germany. In particular, the number of revisions is expected to rise because of higher life expectancy and procedures performed on younger patients, impacting the budgets of health-care systems. Quality transparency is the basis of holistic patient pathway optimization. Nevertheless, a nation-wide cross-sectoral assessment of quality from a patient perspective does not yet exist. Several studies have shown that the use of patient-reported outcome measures (PROMs) is effective for measuring quality and monitoring post-treatment recovery. For the first time in Germany, we test whether early detection of critical recovery paths using PROMs after TKR/THR improves the quality of care in a cost-effective way and can be recommended for implementation into standard care.Methods/designThe study is a two-arm multi-center patient-level randomized controlled trial. Patients from nine hospitals are included in the study. Patient-centered questionnaires are employed to regularly measure digitized PROMs of TKR/THR patients from the time of hospital admission until 12 months post-discharge. An expert consortium has defined PROM alert thresholds at 1, 3, and 6 months to signal critical recovery paths after TKR/THR. An algorithm alerts study assistants if patients are not recovering in line with expected recovery paths. The study assistants contact patients and their physicians to investigate and, if needed, adjust the post-treatment protocol. When sickness funds’ claims data are added, the cost-effectiveness of the intervention can be analyzed.DiscussionThe study is expected to deliver an important contribution to test PROMs as an intervention tool and examine the determinants of high-quality endoprosthetic care. Depending on a positive and cost-effective impact, the goal is to transfer the study design into standard care. During the trial design phase, several insights have been discovered, and there were opportunities for efficient digital monitoring limited by existing legacy care models. Digitalization in hospital processes and the implementation of digital tools still represent challenges for hospital personnel and patients. Furthermore, data privacy regulations and the separation between the in- and outpatient sector are roadblocks to effectively monitor and assess quality along the full patient pathway.Trial registrationGerman Clinical Trials Register: DRKS00019916. Registered November 26, 2019 – retrospectively registered.

Factors lead to return to sports and recreational activity after total knee replacement - A retrospective study.

Introduction: The number of total knee replacements performed (TKR) is increasing and so are patient expectations and functional demands. The mean age at which orthopedic surgeons may indicate TKR is decreasing, and therefore return to sport (RTS) after TKR is often an important expectation for patients. The aim of this study was to analyze the mid-term RTS, recreational activities, satisfaction level, and forgotten joint level after TKR. Methods: Between January 2015 and December 2016, 536 TKR (same implant design, same technique) were performed in our center. The mean age at survey was 69 years with a mean follow-up of 43 months. All patients who did not have a follow-up in the last 6 months were called. Finally, 443 TKR were analyzed. RTS was assessed using the University of California Los Angeles Scale (UCLA), forgotten joint score (FJS), and Satisfaction Score. Results: In this study, 85% of patients had RTS after TKR with a mean UCLA score increasing from 4.48 to 5.92 and a high satisfaction rate. Satisfaction with activity level was 93% (satisfied and very satisfied patients). The RTS is more important for people with a higher preoperative UCLA score and a lower American Society of Anesthesiologist score (ASA). Each point increase in ASA score is associated with reduced probability to RTS by 52%. Discussion: RTS and recreational activity were likely after TKR with a high satisfaction score. Preoperative condition and activity are the two most significant predictive factors for RTS. Level of evidence: Retrospective case series, level IV.

PMS22 ANNUAL COST OF PATIENTS UNDERGOING A TOTAL KNEE REPLACEMENT IN FRANCE

Knee osteoarthritis is one of the most common joint diseases in the world. The rate of total knee replacement (TKR) has more than doubled over the last fifteen years in France (166.8 TKRs per 100,000 population in 2016) despite the most recent guidelines that recommend TKR as the last option if all other treatments have failed. The two aims of this study were to determine the costs for French patients undergoing TKR due to knee osteoarthritis and to estimate the potential cost savings from the point of view of the French social health insurer if the number of total knee replacements were reduced. The 2018 national hospital database (PMSI) was used to establish annual costs of patients undergoing TKR due to knee osteoarthritis in France. We carried out a one-year budget impact analysis to determine the savings incurred if TKRs were reduced by 8% based on lowering the rate of surgeries to match the OECD average. Alternative intervention to surgery was a combination of pharmacological and non-pharmacological treatments and the costs for the alternative interventions were estimated using French tariffs (€, 2018). In 2018, 96,467 French patients had a TKR due to knee osteoarthritis. Their mean age was 70.6 years and 60% were females. The average cost of a TKR was €6,555 per patient and total annual cost was €632,314,517. Cost savings accounted for €48 million when the number of TKRs performed were reduced. This analysis provides real world data on the potential cost savings if total knee replacements are decreased in France. Given the available evidence on the minimal QALY losses that occur when restricting TKRs, a better allocation of resources could liberate funds for more cost-effective interventions.

Magnetic Resonance Imaging of Complications in Total Knee Arthroplasty: A Pictorial Essay

With the ever-increasing number of total knee replacement, the demand for early diagnosis of post arthroplasty complications has increased as well. The various complications associated with total knee replacement include bursitis, tendinitis, periprosthetic fracture, infection, instability, malalignment, loosening, prosthesis fracture, osteolysis, soft tissue impingement, and extensor mechanism problems. Radiographs and nuclear imaging, earlier the mainstays for evaluation of post arthroplasty knee, have vast limitations, especially in evaluating the soft tissue details which account for the symptoms in a significant number of patients. Magnetic resonance with special modifications, i.e. metal artifact reduction sequences, is of immense help in a detailed evaluation of these soft tissue complications and is advisable in all patients where the cause cannot be determined on plain radiographs.

A smart knee implant using triboelectric energy harvesters

Although the number of total knee replacement (TKR) surgeries is growing rapidly, functionality and pain-reduction outcomes remain unsatisfactory for many patients. Continual monitoring of knee loads after surgery offers the potential to improve surgical procedures and implant designs. The goal of this study is to characterize a triboelectric energy harvester under body loads and to design compatible frontend electronics to digitize the load data. The harvester prototype would be placed between the tibial component and polyethylene bearing of a TKR implant. The harvester generates power from the compressive load. To examine the harvester output and the feasibility of powering a digitization circuitry, a triboelectric energy harvester prototype is fabricated and tested. An axial tibiofemoral load profile from normal walking (gait) is approximated as a 1 Hz sine wave signal and is applied to the harvester. Because the root mean square of voltages generated via this phenomenon is proportional to the applied load, the device can be simultaneously employed for energy harvesting and load sensing. With an approximated knee cyclic load of 2.3 kN at 1 Hz, the harvester generated output voltage of 18 V rms, and an average power of 6 μW at the optimal resistance of 58 MΩ. The harvested signal is rectified through a negative voltage converter rectifier and regulated through a linear-dropout regulator with a combined efficiency of 71%. The output of the regulator is used to charge a supercapacitor. The energy stored in the supercapacitor is used for low resolution sensing of the load through a peak detector and analog-to-digital converter. According to our analysis, sensing the load several times a day is feasible by relying only on harvested power. The results found from this work demonstrate that triboelectric energy harvesting is a promising technique for self-powering load sensors inside knee implants.

The sociocultural effects on orthopedic surgeries in Taiwan

Various sociocultural factors affect healthcare-seeking behaviors. In Taiwanese society, superstitions and lunar festivals play important roles in people’s lives. We investigated the impact of “Ghost Month” (the 7th lunar month) and Chinese New Year (the 12th lunar month and the 1st lunar month of the following year) on the number of elective surgeries and emergent surgeries in Taiwan. The number of total knee replacement (TKR) surgeries and proximal femur fracture (PFF) surgeries in each lunar month from 2000 to 2011 were extracted from the Taiwan National Health Insurance Database, a computerized and population-based database. Patients were then sorted by location of residence or gender. The average number of TKR surgeries performed was significantly lower during the 1st, 7th, and 12th lunar months in urban areas, whereas in rural areas this trend was only evident in the 7th and 12th lunar months. There was however, no significant difference in the average number of PFF surgeries in each lunar month except for an increase seen in the 1st lunar month in rural patients (p<0.05). When sorted by gender, the average number of TKR surgeries was significantly decreased in the 7th and 12th lunar months in male patients, and decreased in the 1st, 7th, and 12th lunar months in female patients. In contrast, there was no difference in the average numbers of PFF surgeries in the 7th and 12th lunar months either in male or female patients. We proposed that the timing of elective surgeries such as TKR might be influenced by Ghost Month and Chinese New Year; however, emergent PFF surgeries were not significantly influenced by sociocultural beliefs and taboos in Taiwan.

Is there a relation between length of stay and early complications rate after total knee arthroplasty? Results of 1065 patients

Introduction The number of total knee replacements is rapidly increasing as a result of population ageing. Trying to decrease the costs associated with this procedure, there is an increased effort to diminish hospital length of stay without raising the complications rates. Aim Evaluate if there is a relationship between a decrease in hospital's length of stay and early complications within 30 days postoperatively and all-cause readmissions within 30 days after discharge. Material and methods Retrospective revision of 1065 patients submitted to total knee arthroplasty between July 2007 and June 2013 in our institution. Data was collected by analyzing patient's records, in what regards early complications and readmissions within the first 30 days after discharge and the length of stay in hospital after surgery. The statistical analysis was performed using SPSS v22. Significance was defined as P Resultats The population of the study is composed of 1065 patients. The length of stay decreased from 5.18 ± 2.28 days between July 1st 2007 and September 31st 2007, to 4.76 ± 3.2 days between April 1st 2013 and June 30th 2013. Observed complications were 49 (4.6%), with 19 (1.8%) infectious events, 10 (0.9%) suture dehiscences, 9 (0.8%) hemorrhagic events, 3 (0.3%) thromboembolic events, 3 (0.3%) gastrointestinal events, 1 (0.1%) periprosthetic fracture, 1 (0.1%) miocardial infarction, 1 (0.1%) acute renal failure, 1 (0.1%) patellar tendon rupture, 2 (0.2%) deaths. All-cause readmission rate within 30 days after discharge was 6.1%. Discussion There is a decrease in the total length of stay. This is due to the current trend about decreasing hospital length of stay after TKA and positive feedback from the Rehabilitation department. It can be observed a low rate of complications in what concerns DVT, hemorrhagic events and other events like gastrointestinal or renal, which reinforces the confidence of safe earlier discharges. The infection and DVT rates are low when considering the published literature. There are limitations in what concerns the time frame, it is a short postoperative period. Hospital records always have the limitation of underreporting these events. The association between length of stay and early complications rate was not significant (P = 0.2019) as well as all-cause readmission rate (P = 0.280). Conclusion It was not found any significant association between length of stay and both early complications rate and all-cause readmission rate. These findings are similar to other studies and reinforce the current trend about short stays after total knee replacements, which is better for patient safety and cost control.

Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Improving outcomes in total knee arthroplasty-do navigation or customized implants have a role?

Modern total knee arthroplasty is effective at treating the pain and disability associated with osteoarthritis. The number of total knee replacements done in the USA continues to increase. Despite the great care taken during all of these procedures, some patients remain dissatisfied with their outcome. While this dissatisfaction is likely multifactorial, malalignment of the prosthetic components is a major cause of postoperative complications. A neutral mechanical axis plus or minus 3° is felt to have a positive impact on the survivorship of the prosthesis. Conventional instrumentation has been shown to have a significant number of total knee replacements that lie well outside a neutral coronal alignment. With that in mind, significant effort has been placed into the development of technology to improve the overall alignment of the prosthesis. In order to reduce the number of outliers, several companies have developed cost-effective systems to aid the surgeon in achieving a more predictably aligned prosthesis in all three planes. We will review the literature that is available regarding several of these tools to examine if navigation or custom guides improve outcomes in total knee arthroplasty. Our review supports that while both navigation and custom implants guides seem to be a cost effective way to achieve a predictable mechanical alignment of a total knee prosthesis therefore reducing the number of outliers, the cost may be increased operative times with no perceived difference in patient satisfaction with navigation custom guides.

Hip Joint Muscle Forces during Stair Ascent Following Total Knee Replacement

The number of total knee replacement (TKR) surgeries have increased steadily in recent years. Research has shown that TKR patients have to compensate during stair walking following surgery, especially at the hip joint. Muscle modeling techniques have been utilized to simulate muscle force during specific movements. An understanding of the hip muscle forces during stair ascent following TKR would provide a greater understanding of the compensation necessary by TKR patients. Thus helping direct physical therapy interventions both prior to and after a TKR. PURPOSE: To compare hip joint muscle forces between health and TKR patients during stair ascent. METHODS: Five TKR (age: 63.6) and five healthy (age: 57.8) participants performed stair ascent using a 5-step staircase with 3 instrumented steps at a self-selected pace. A generic model of 12 segments, 19-degrees of freedom and 92 muscle (Gait 2392 Model, OpenSim 3.0.1, SimTK, Stanford, CA, USA) was used to simulate muscle forces of the major muscles surrounding the hip joint during the stance phase of the second step during stair ascent. RESULTS: During the loading phase, TKR patients had greater peak muscle force of the sartorius (0.68 N/kg vs. 0.34 N/kg), tensor fascia latte (0.88 N/kg vs. 0.54 N/kg), illiacus (5.49 N/kg vs. 1.77 N/kg), and psoas major (5.91 N/kg vs. 2.95 N/kg) when compared with healthy individuals (p < 0.05). During the push-off phase, the peak sartorius (0.68 N/kg vs. 0.42 N/kg) and adductor magnus (1.12 N/kg vs. 0.63 N/kg) muscle forces were greater in TKR patients compared to controls, while the adductor longus muscle force was greater in controls (1.09 N/kg vs. 0.65 N/kg). CONCLUSION: TKR patients in this study showed greater force in muscles responsible for hip flexion, abduction and lateral rotation during the loading phase of gait. During push-off the results were not as consistent. The adductor magnus force was greater, while the adductor longus force was reduced in TKR participants compared to controls. This study suggests that there are muscle force compensations at the hip joint during stair ascent following a TKR. The findings of this study suggest a number of muscles that have greater force demands during stair ascent following a TKR. Strengthening these muscles in post-TKR therapy may be one way to improve the recovery following surgery.

Osteosynthesis after periprosthetic fractures of the knee joint

Periprosthetic fractures around the knee joint are of increasing relevance due to increasing numbers of total knee replacements and increasing life expectations. These fractures can be a real challenge due to an often limited patient compliance, reduced bone quality and impaired bone perfusion of potential intramedullary shafts resulting in poor healing and lack of fixation options for screws. These fractures necessitate special knowledge and approaches, which are systematically dealt with in this article, beginning with the correct diagnostics through to the most recent developments in the field of osteosynthetic techniques. The trends of minimally invasive techniques are presented and the options and limitations are described.

193. Novel Classification of Knee Osteoarthritis Severity Based on Spatiotemporal Analysis

summary Objective: To describe a novel classification method for knee osteoarthritis (OA) based on spatiotemporal gait analysis. Methods: Gait analysis was initially performed on 2911 knee OA patients. Females and males were analyzed separately because of the influence of body height on spatiotemporal parameters. The analysis included the three stages of clustering, classification and clinical validation. Clustering of gait analysis to four groups was applied using the kmeans method. Two-thirds of the patients were used to create a simplified classification tree algorithm, and the model’s accuracy was validated by the remaining onethird. Clinical validation of the classification method was done by the short form 36 Health Survey (SF-36) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires. Results: The clustering algorithm divided the data into four groups according to severity of gait difficulties. The classification tree algorithm used stride length and cadence as predicting variables for classification. The correct classification accuracy was 89.5%, and 90.8% for females and males, respectively. Clinical data and number of total joint replacements correlated well with severity group assignment. For example, the percentages of total knee replacement (TKR) within 1 year after gait analysis for females were 1.4%, 2.8%, 4.1% and 8.2% for knee OA gait grades 1e4, respectively. Radiographic grading by Kellgren and Lawrence was found to be associated with the gait analysis grading system. Conclusions: Spatiotemporal gait analysis objectively classifies patients with knee OA according to disease severity. That method correlates with radiographic evaluation, the level of pain, function, number of TKR.

Dramatic increase in total knee replacement utilization rates cannot be fully explained by a disproportionate increase among younger patients.

The incidence of total knee replacement in the United States more than doubled between 1999 and 2008, increasing from approximately 263,000 to 616,000 cases. The purpose of this study is to evaluate the claim that there has been a disproportionate increase in knee replacements among younger patients owing to expanding indications for the procedure in this group. Data on the US population for individuals 18 to 44 years old, 45 to 64 years old, and 65 years and older were obtained from census data; the number of total knee replacements performed annually in each age group was acquired from the Agency for Healthcare Research and Quality and per-capita incidence rates were calculated. Applying the 1999 rates to the 2008 population, the number of knee replacements anticipated on the basis of population growth for each cohort was determined and compared with the number observed, yielding the unexplained growth. The data revealed that in 2008, approximately 305,000 knee replacements were performed beyond the number predicted by population growth alone. The largest segment of growth (151,000 cases) was among patients 65 years and older; the per-capita growth rate was highest in this cohort as well, increasing from 5.2 to 9.1 procedures per 1,000 individuals. The data show conclusively that a disproportionate increase in knee replacements among younger patients is not a full explanation for the growth in utilization. In fact, it is not even the best among alternative explanations. The main locus of growth was among traditional patients 65 years and older.