Objectives: The development of effective fall prevention programs requires understanding of underlying causes of falls. Measurement tools are needed that predict the risk of falling and give objective assessment of balance function needed for daily life performance. The ultimate goal of the activities within this work package is to combine the expertise of different disciplines for the development of balance assessment tools that meet the requirements for large-scale intervention studies and routine-use in clinical settings. The knowledge needed to develop these instruments and measures is scattered over a wide range of disciplines (ranging from physiology to electrical engineering). The objectives of this work package are to combine expertise from different disciplines to transfer knowledge between disciplines, to co-operate in designing research and provide an intellectual environment for interdisciplinary projects and dissemination of knowledge into disciplines working in the clinical field. Description of work: Recent technological developments allow for the measurement of human movement under real-life conditions by means of lightweight ambulatory equipment. This novel approach to the analysis of human movement can potentially fill the need for objective field instruments. However, suitable methods for balance assessment need to be developed. Activities of this work package are aimed at co-ordinating the development of methods that can be used in the clinical field for assessment of posture and gait. The work encompasses the organization of workshops, the co-ordination of research, and dissemination of knowledge through publications, teaching and training. Members co-ordinate their individual research efforts in such a way that the different research lines support and reinforce each other. The coordination of research will involve joint experiments and the definition of assessment protocols that can be used in the individual studies of all participating groups. The work focuses on the analysis of kinematic patterns during walking and standing in a natural environment by means of ambulatory equipment. Appropriate methods for signal acquisition and analysis are being developed. Protocols are being designed which specifically address different aspects of balance control (i.e. mental load, sensory dependence, and effects of mechanical manipulations). Laboratory tasks, which have proven to be sensitive for balance dysfunction, will be translated into valid, reliable and easy-to-use procedures for field use. These field instruments are based upon a sound theoretical framework against which the results can be understood and interpreted. In order to address the validity and predictive value of field instruments, longitudinal studies need to be performed that are in accordance with the work in other work packages. Apart from balance assessment procedures, activity levels, history of falls, and future falls need to be assessed. We expect this novel approach to give insight in the relation between objective measures of balance function, activity level and number of falls. Thus, the occurrence of falls can be related to (changes in) activity level

Introduction. Partial knee arthroplasty (PKA) has demonstrated the potential to improve patient satisfaction over total knee arthroplasty. It is however perceived as a more challenging procedure that requires precise adaptation to the complex mechanics of the knee. A recently developed PKA system aims to address these challenges by anatomical, compartment specific shapes and fine-tuned mechanical instrumentation. We investigated how closely this PKA system replicates the balance and kinematics of the intact knee. Materials and Methods. Eight post-mortem human knee specimens (age: 55±11 years, BMI: 23±5, 4 male, 4 female) underwent full leg CT scanning and comprehensive robotic (KUKA KR140 comp) assessments of tibiofemoral and patellofemoral kinematics. Specimens were tested in the intact state and after fixed bearing medial PKA. Implantations were performed by two experienced surgeons. Assessments included laxity testing (anterior-posterior: ±100 N, medial-lateral: ±100 N, internal-external: ±3 Nm, varus- valgus: ±12 Nm) under 2 compressive loads (44 N, 500 N) at 7 flexion angles and simulations of level walking, lunge and stair descent based on in-vivo loading profiles. Kinematics were tracked robotically and optically (OptiTrack) and represented by the femoral flexion facet center (FFC) motions. Similarity between intact and operated curves was expressed by the root mean square of deviations (RMSD) along the curves. Group data were summarized by average and standard deviation and compared using the paired Student's T-test (α = 0.05). Results. During the varus-valgus balancing assessment the medial and lateral opening of the PKAs closely resembled the intact openings across the full arch of flexion, with RMSD values of 1.0±0.5 mm and 0.4±0.2 mm respectively. The medial opening was nearly constant across flexion, its average was not statistically different between intact (3.8±1.0 mm) and PKA (4.0±1.1 mm) (p=0.49). Antero-posterior envelope of motion assessments revealed a close match between the intact and PKA group for both compression levels. Net rollback was not statistically different, either under low compression (intact: 10.9±1.5 mm, PKA: 10.7±1.2, p=0.64) or under high compression (intact: 13.2±2.3 mm, PKA: 13.0±1.6 mm, p=0.77). Similarly, average laxity was not statistically different, either under low (intact: 7.7±3.2 mm, PKA: 8.6±2.5 mm, p=0.09) or under high (intact: 7.2±2.6 mm, PKA: 7.8±2.2 mm, p=0.08) compression. Activities of daily living exhibited a close match in the anterior-posterior motion profile of the medial condyle (RMSD: lunge: 2.2±1.0 mm, level walking: 2.4±0.9 mm, stair descent: 2.2±0.6 mm) and lateral condyle (RMSD: lunge: 2.4±1.4 mm, level walking: 2.2±1.4 mm, stair descent: 2.7±2.0 mm). Patellar medial-lateral tilt (RMSD: 3.4±3.8°) and medial-lateral shift (RMDS: 1.5±0.6 mm) during knee flexion matched closely between groups. Conclusion. Throughout the comprehensive functional assessments the investigated PKA system behaved nearly identical to the intact knee. The small residuals are unlikely to have a clinical effect; further studies are necessary as cadaveric studies are not necessarily indicative of clinical results. We conclude that PKA with anatomical, compartment specific shapes and fine-tuned mechanical instrumentation can be adapted precisely to the complex mechanics of the knee and replicates intact knee balance and kinematics very closely

Aims

Sagittal plane imbalance (SPI), or asymmetry between extension and flexion gaps, is an important issue in total knee arthroplasty (TKA). The purpose of this study was to compare SPI between kinematic alignment (KA), mechanical alignment (MA), and functional alignment (FA) strategies.

Backgrounds. In order to permit soft tissue balancing under more physiological conditions during total knee arthroplasties (TKAs), we developed an offset type tensor to obtain soft tissue balancing throughout the range of motion with reduced patella-femoral (PF) and aligned tibiofemoral joints and reported the intra-operative soft tissue balance assessment in cruciate-retaining (CR) and posterior-stabilized (PS) TKA [1, 2]. However, the soft tissue balance in unicompartmental knee arthroplasty (UKA) is unclear. Therefore, we recently developed a new tensor for UKAs that is designed to assist with soft tissue balancing throughout the full range of motion. The first purpose of the present study is to assess joint gap kinematics in UKA. Secondly, we attempted to compare the pattern in UKA with those in CR and PS TKA with the reduced PF joint and femoral component placement, which more closely reproduces post-operative joint alignment. Methods. Using this tensor, we assessed the intra-operative joint gap measurements of UKAs performed at 0, 10, 30, 45, 60, 90, 120 and 135° of flexion in 20 osteoarthritic patients. In addition, the kinematic pattern of UKA was compared with those of CR and PS TKA that were calculated as medial compartment gap from the previous series of this study. Results. While the joint gap measurements of UKAs increased from full extension to extension (10 degrees of flexion), these values remained constant throughout the full range of motion. Of note, the gap values of CR TKA were significantly smaller from midrange to deep flexion compared with PS TKA, and furthermore UKA showed a significantly smaller gap from extension to midrange flexion compared with CR TKA. Conclusions. Accordingly, we conclude that the intra-operative joint gap kinematic pattern in UKA differs from the pattern in TKA

There are some reports that the invasive surgery of knee joint replacement repair static and dynamic balance. We investigated the changes in static and dynamic balance and muscle strength in pre- and postoperative of TKA and UKA for the purpose of assessing time dependent improvement. A total of 168 patients (137 TKA; mean age 75.3, 31 UKA; mean age 78.1) were recruited to the study. These patients underwent static and dynamic balance assessment and muscle strength pre operation and 3, 6, 12 months post operation. The parameters of assessment were one leg standing time (open or close eyes), postural sway test (open or close eyes), 3m timed-up-and-go test, maximum stride and Isokinetic muscle strength. We have evaluated both the absolute value and the index which divided the value of the post-operation with the value of pre-operation. Alignment had improved significantly after surgery in TKA and UKA. Isokinetic muscle strength (Fig. 1), one leg standing time with open eyes, 3m timed-up-and-go test (Fig. 2) and maximum stride showed better improvement than pre operation at 3, 6, and 12 months after surgery in TKA and UKA. On the other hand, one leg standing time with close eyes and postural sway test showed no improvement than pre operation at any time after operation (Fig. 3). Butpostural sway test in UKA showed the improvement trend at 3 months after surgery. In contrast, those test in TKA showed no improvement at 3 months after surgery (Fig. 3). Our result showed the improvement of balance function correlated with muscle recovery and improvement of lower limb alignment than equilibrium function after the artificial knee joint replacement surgery. Because one leg standing time with close eyes and one leg postural sway test represent the equilibrium function than other tests. It is interesting that significant difference in the recovery of postural sway in three months after surgery in UKA compared with TKA

Dislocation remains a common complication following total hip arthroplasty, second only to aseptic loosening as a cause of revision. Factors thought to play a role in dislocation include cup and stem alignment, soft tissue tension, surgical approach, patient factors, and design features of the prosthesis, including femoral head size. We analysed all consecutive total hip replacements at one institution over a 17 year period. Criteria for study inclusion were hips replaced due to primary osteoarthritis with no previous surgery, femoral head sizes of 28mm and 32mm only, and at least one year from date of surgery. 3682 hips fulfilled these criteria. All procedures were carried out using a posterolateral approach with enhanced posterior repair, and a standard method of intraoperative soft tissue balance assessment. The rate of dislocation was 1.6%. 32mm femoral head size was associated with a statistically significant lower rate of dislocation. However, after controlling for different follow-up times between 28mm and 32mm heads, this difference was no longer observed. Older age at time of surgery and decreased cup anteversion were shown to be significantly associated with an increased risk of dislocation. Ceramic on ceramic bearing surface was significantly associated with a decreased risk of dislocation, after controlling for age, bearing wear and time from surgery. Cup inclination, gender, BMI, and preoperative hip score were not related to dislocation risk. Our dislocation rate may reflect current dislocation rates of surgeons using the posterolateral approach with posterior capsule and external rotator repair. The risk factors identified and excluded in this study are likely to be relevant to all surgeons who utilise this approach in total hip arthroplasty

Dislocation remains a common complication following total hip arthroplasty, second only to aseptic loosening as a cause of revision. Factors thought to play a role in dislocation include cup and stem alignment, soft tissue tension, surgical approach, patient factors, and design features of the prosthesis, including femoral head size. We analysed all consecutive total hip replacements at one institution over a 17 year period. Criteria for study inclusion were hips replaced due to primary osteoarthritis with no previous surgery, femoral head sizes of 28mm and 32mm only, and at least one year from date of surgery. 3682 hips fulfilled these criteria. All procedures were carried out using a posterolateral approach with enhanced posterior repair, and a standard method of intraoperative soft tissue balance assessment. The rate of dislocation was 1.6%. 32mm femoral head size was associated with a statistically significant lower rate of dislocation. However, after controlling for different follow-up times between 28mm and 32mm heads, this difference was no longer observed. Older age at time of surgery and decreased cup anteversion were shown to be significantly associated with an increased risk of dislocation. Ceramic on ceramic bearing surface was significantly associated with a decreased risk of dislocation, after controlling for age, bearing wear and time from surgery. Cup inclination, gender, BMI, and preoperative hip score were not related to dislocation risk. Our dislocation rate may reflect current dislocation rates of surgeons using the posterolateral approach with posterior capsule and external rotator repair. The risk factors identified and excluded in this study are likely to be relevant to all surgeons who utilise this approach in total hip arthroplasty

Aims

It is unknown whether gap laxities measured in robotic arm-assisted total knee arthroplasty (TKA) correlate to load sensor measurements. The aim of this study was to determine whether symmetry of the maximum medial and lateral gaps in extension and flexion was predictive of knee balance in extension and flexion respectively using different maximum thresholds of intercompartmental load difference (ICLD) to define balance.

ProFaNE, Prevention of Falls Network Europe, is a four year project, funded by the European Community Framework 5. It is a thematic network, coordinated by the University of Manchester, UK, with 25 partners across Europe. There are also Network Associates from a number of EU and non-EU countries who give their advice and experience at meetings, seminarsand conferences. The aim is to bring together workers from around Europe to focus on a series of tasks aimed at developing multi-factorial prevention programmes to reduce the incidence of falls and fractures amongst elderly people. The work of ProFaNE is practical, both in terms of developing the evidence base for implementation of effective interventions and encouraging best practice across Europe. The task of each work package is to convene workshops, undertake personnel exchanges and set up collaborative studies, data sharing in order to develop evidence based protocols and publications which can be used to implement change. Work Package 1 - Fall prevention trials - Taxonomy of interventions and agreed set of outcomes. An agreed and standardised set of outcome definitions and measures is important to improve the robustness of data from intervention studies, will enable comparison across studies, good quality measurement in multi-centre trials, and facilitate meta-analysis of trial results. A taxonomy of interventions will facilitate comparisons between studies, help to determine the most effective components or sub-components of interventions, and aid the decision making process of policy makers and health insurance plans. A Consensus taxonomy and outcome measures statement, Trial design statement, Meta - analysis protocol and Self help materials will be produced. Work Package 2 - Clinical Assessment and Outcomes. Aims to gain an understanding of the current issues surrounding falls prevention across Europe and to embrace at national and international level, the different political and health service agendas in each country such that recommendations can ultimately be translated into working models of practice. They will establish a robust network of key members across Europe to facilitate the effective and efficient promulgation of evidence likely to influence service developments at national and local level and derive a consensus approach to assessment and management of older people at risk of falling in a variety of clinical settings using the existing evidence base as well as inviting expert opinions in the field. Work Package 3 - Assessment of balance function and prediction of falls. Measurement tools are needed that predict the risk of falling and give objective assessment of balance function needed for daily life performance. The ultimate goal of the activities within this work package is to combine the expertise of different disciplines for the development of balance assessment tools that meet the requirements for large-scale intervention studies and routine-use in clinical settings. The knowledge needed to develop these instruments and measures is scattered over a wide range of disciplines (ranging from physiology to electrical engineering). Work Package 4 - Psychological aspects of falling. We need to understand the psychosocial factors which affect the benefit of falling prevention programmes for older people. These include attitudes to falling (such as fear) and factors that promote or reduce uptake of and adherence to a range of falling-related interventions, including exercise. Understanding of attitudes and behaviour will inform guidelines for the design of interventions, and development of measures to assess relevant attitudes. We also co-ordinate development of self-test indices that older people can use to evaluate their own risk of falling, together with guidance as to the actions they should take to prevent falling