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Summary Background/Objective Activity is increasingly being recognized as a highly relevant parameter in all areas of healthcare for diagnosis, treatment, or outcome assessment, especially in orthopaedics where the movement apparatus is directly affected. Therefore, the aim of this study was to develop, describe, and clinically validate a generic activity-monitoring algorithm, satisfying a combination of three criteria. The algorithm must be able to identify, count, and time a large set of relevant daily activities. It must be validated for orthopaedic patients as well as healthy individuals, and the validation must be in a setting that mimics free-living conditions. Methods Using various technical solutions, such as a dual-axis approach, dynamic inclinometry (hip flexion), and semiautomatic calibration (gait speed), the algorithms were designed to count and time the following postures, transfers, and activities of daily living: resting/sitting, standing, walking, ascending and descending stairs, sit–stand transitions, and cycling. In addition, the number of steps per walking bout was determined. Validation was performed with healthy individuals and patients who had undergone unilateral total joint arthroplasty, representing a wide spectrum of functional capacity. Video observation was used as the gold standard to count and time activities in a validation protocol approaching free-living conditions. Results In total 992 and 390 events (activities or postures) were recorded in the healthy group and patient group, respectively. The mean error varied between 0% and 2.8% for the healthy group and between 0% and 7.5% for the patient group. The error expressed in percentage of time varied between 2.0% and 3.0% for both groups. Conclusion Activity monitoring of orthopaedic patients by counting and timing a large set of relevant daily life events is feasible in a user- and patient-friendly way and at high clinical validity using a generic three-dimensional accelerometer and algorithms based on empirical and physical methods. The algorithms performed well for healthy individuals as well as patients recovering after total joint replacement in a challenging validation set-up. With such a simple and transparent method real-life activity parameters can be collected in orthopaedic practice for diagnostics, treatments, outcome assessment, or biofeedback.

Background The demands of the younger and more active current total knee arthroplasty (TKA) patients are not in line with the current outcome assessments. Therefore, new questionnaires are developed or adjusted, as with the popular 1989 Knee Society Score (KSS). This study is the first to investigate the clinimetric parameters of the patient-reported outcome measurement (PROM) part of the 2011 KSS. Methods Four-hundred-fifteen primary Dutch TKA patients were scored using the PROM part of the 2011 KSS. The scale is subdivided into an Objective (not evaluated), Satisfaction, Expectation and Function subscales. Clinimetric quality was evaluated by response and completion rate, test–retest reliability (n=29, intraclass correlation coefficient), internal consistency (n=172, Cronbach's alpha), construct validity (Pearson's correlations with 1989 KSS (n=75) and KOOS-PS (n=139)) and responsiveness (n=20, paired-samples t -test, effect sizes and floor and ceiling effects). Results A response rate of 96% and completion rate of 43% were found. Reliability and internal consistency proved excellent with ICCs≥0.79 and Cronbach's alpha≥0.76 for all subscales. Strong correlations were found between the Function subscales of the 2011 KSS and KOOS-PS (r=−0.60 to −0.83). All subscales improved significantly after intervention, with exception of Walking & Standing and Discretionary Activities. 23% reached the maximum score postoperatively in Walking & Standing, indicating a ceiling effect. Conclusions The 2011 KSS is a reliable, internal consistent, construct valid and responsive questionnaire to assess the outcome of the Dutch TKA patients. Optimizations (e.g. shortening the scale, simplified design) are recommended to increase the disappointing completion rate. Clinical relevance The 2011 KSS is a reliable, internal consistent, construct valid and responsive questionnaire to assess the outcome of the Dutch TKA patients.

Shoulder-related dysfunction is the second most common musculoskeletal disorder and is an increasing burden on health-care systems. Commonly used clinical questionnaires suffer from subjectivity, pain dominance and a ceiling effect. Objective functional measurement has been identified as a relevant issue in clinical rehabilitation. Inertia based motion analysis (IMA) is a new generation of objective outcome assessment tool; it can produce objective movement parameters while being fast, cheap and easy to operate. In this prospective study, an inertial sensor comprising a three-dimensional accelerometer and gyroscope is attached at the humerus to measure shoulder movements during two motion tasks in patients with subacromial impingement syndrome at baseline and at five-year after treatment. One hundred healthy subjects served as healthy reference database and 15 patients were measured pre- and post-treatment. IMA was better able to detect improvement in shoulder movements compared to the clinical questionnaires (Disability of Arm, Shoulder and Hand (DASH) and Simple Shoulder Test (SST); p < 0.05) and was hardly correlated with the clinical questionnaires (Pearson R = 0.39). It may therefore add an objective functional dimension to outcome assessment. The fast assessment (t < 5 min) of a simple motion test makes it suitable for routine clinical follow-up.

Shoulder-related dysfunction is the second most common musculoskeletal disorder and is responsible for an increasing burden on health-care systems. Commonly used clinical outcome scores suffer from subjectivity, pain dominance and a ceiling effect. Objective functional measurement has been identified as a relevant issue in clinical rehabilitation. In recognition of this goal simple techniques for routine clinical application have been investigated with some success. Inertia based motion analysis (IMA) is a new generation of objective outcome assessment tool; it can produce objective movement parameters while being fast, cheap and easy to operate. This study investigates if a simple IMA shoulder test is suitable as a functional outcome measure for routine clinical follow-up. We measured 100 healthy subjects and 50 patients with confirmed unilateral shoulder pathology. Two motion tasks were performed on both shoulders and two simple motion parameters based on angular rate and acceleration were calculated. Patients were also assessed by the disability of arm, shoulder and hand (DASH) and the simple shoulder test. IMA produced high intra- (ICC = 0.94) and inter-assessor reliability (ICC = 0.90). Asymmetry was3 times higher in patients than in healthy controls (p0.01). Healthy and pathological subjects could be distinguished with high diagnostic sensitivity (84.0%) and specificity (81.0%). There was a weak correlation between the IMA shoulder score and the clinical questionnaires (Pearson R0.25), as it may add an objective functional dimension to outcome assessment. The fast assessment (t5 min) of a simple motion task makes it workable for routine clinical follow-up. The IMA shoulder test adds objective information on functional capacity to the clinical scores and may help the physician in his decision-making, follow-up of treatment, effect of training and possibly lead to the development of new therapeutic interventions.

Dynamic imbalance caused by external perturbations to gait can successfully be counteracted by adequate recovery responses. The current study investigated how the recovery response is moderated by age, walking speed, muscle strength and speed of information processing. The gait pattern of 50 young and 45 elderly subjects was repeatedly perturbed at 20% and 80% of the first half of the swing phase using the Timed Rapid impact Perturbation (TRiP) set-up. Recovery responses were identified using 2D cameras. Muscular factors (dynamometer) and speed of information processing parameters (computer-based reaction time task) were determined. The stronger, faster reacting and faster walking young subjects recovered more often by an elevating strategy than elderly subjects. Twenty three per cent of the differences in recovery responses were explained by a combination of walking speed (B=-13.85), reaction time (B=-0.82), maximum extension strength (B=0.01) and rate of extension moment development (B=0.19). The recovery response that subjects employed when gait was perturbed by the TRiP set-up was modified by several factors; the individual contribution of walking speed, muscle strength and speed of information processing was small. Insight into remaining modifying factors is needed to assist and optimise fall prevention programmes.

18F-fluoride PET is a promising noninvasive method for measuring bone metabolism and bone blood flow. The purpose of this study was to assess the performance of various clinically useful simplified methods by comparing them with full kinetic analysis. In addition, the validity of deriving bone blood flow from K1 of 18F-fluoride was investigated using 15O-H2O as a reference. Methods: Twenty-two adults (mean age ± SD, 44.8 ± 25.2 y), including 16 patients scheduled for bone surgery and 6 healthy volunteers, were studied. All patients underwent dynamic 15O-H2O and 18F-fluoride scans before surgery. Ten of these patients had serial PET measurements before and at 2 time points after local bone surgery. During all PET scans, arterial blood was monitored continuously. 18F-fluoride data were analyzed using nonlinear regression (NLR) and several simplified methods (Patlak and standardized uptake value [SUV]). SUV was evaluated for different time intervals after injection and after normalizing to body weight, lean body mass, and body surface area, and simplified measurements were compared with NLR results. In addition, changes in SUV and Patlak-derived fluoride influx rate (Ki) after surgery were compared with corresponding changes in NLR-derived Ki. Finally, 18F-fluoride K1 was compared with bone blood flow derived from 15O-H2O data, using the standard single-tissue-compartment model. Results: K1 of 18F-fluoride correlated with measured blood flow, but the correlation coefficient was relatively low (r = 0.35, P < 0.001). NLR resulted in a mean Ki of 0.0160 ± 0.0122, whereas Patlak analysis, for the interval 10-60 min after injection, resulted in an almost-identical mean Ki of 0.0161 ± 0.0117. The Patlak-derived Ki, for 10-60 min after injection, showed a high correlation with the NLR-derived Ki (r = 0.976). The highest correlation between Ki and lean body mass-normalized SUV was found for the interval 50-60 min (r = 0.958). Finally, changes in SUV correlated significantly with those in Ki (r = 0.97). Conclusion: The present data support the use of both Patlak and SUV for assessing fluoride kinetics in humans. However, 18F-fluoride PET has only limited accuracy in monitoring bone blood flow.

Innovation and change in postgraduate medical education programs affects teaching hospital organizations, since medical education and clinical service are interrelated. Recent trends towards flexible, time-independent and individualized educational programs put pressure on this relationship. This pressure may lead to organizational uncertainty, unbalance and friction making it an important issue to analyze. The last decade was marked by a transition towards outcome-based postgraduate medical education. During this transition competency-based programs made their appearance. Although competency-based medical education has the potential to make medical education more efficient, the effects are still under debate. And while this debate continues, the field of medical education is already introducing next level innovations: flexible and individualized training programs. Major organizational change, like the transition to flexible education programs, can easily lead to friction and conflict in teaching hospital organizations. This article analyses the organizational impact of postgraduate medical education innovations, with a particular focus on flexible training and competency based medical education. The characteristics of teaching hospital organizations are compared with elements of innovation and complexity theory. With this comparison the article argues that teaching hospital organizations have complex characteristics and behave in a non-linear way. This perspective forms the basis for further discussion and analysis of this unexplored aspect of flexible and competency based education.

The 2011 KSS is a valid clinical TKA questionnaire, but with a low completion rate (42%). Adjustments, focusing on optimizing scale features, are required to improve its clinical use. The low completion rates, non-optimal scale features, lacking rules or a combination of these factors where addressed, leading to the development of the adjusted 2011 KSS (2011 KSS-A). Four-hundred-ninety-nine primary TKA patients were addressed pre- and postoperative by mail. Clinimetric quality was evaluated. Seventy percent responded and 90% completed the scale. Internal consistency proved excellent with Cronbach's Alpha≥0.79 for all subscales. Strong correlations were found between the Functional Activity subscales and KOOS-PS (r=-0.63 to -0.87). All subscales improved significantly after intervention (r-range 14-33%, effect size 0.50-2.85). Postoperatively, ceiling effects were found in the subscales Symptoms (16%) and WalkingStanding (26%). Adjustments led to a shortened and simplified questionnaire while maintaining its clinimetric quality.

BACKGROUND:Functional outcome assessment after total hip arthroplasty often involves subjective patient-reported outcome measures whereas analysis of gait is more objective. The study's aims were to compare subjective and objective functional outcomes after total hip arthroplasty between patients with low and high self-reported levels of pre-operative physical function.METHODS:Patients undergoing total hip arthroplasty (n=36; m/f=18/18; mean age=63.9; SD=9.8 years; BMI=26.3; SD=3.5) were divided into a low and high function subgroup, and prospective measures of WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) function score and gait were compared at baseline and 3 and 12 months post-operatively.FINDINGS:WOMAC function scores significantly improved in both low and high function subgroups at 3 months post-operatively whereas gait parameters only improved in patients with a low pre-operative function. Between 3 and 12 months post-operatively, WOMAC function scores had not significantly further improved whereas several gait parameters significantly improved in the low function group. WOMAC function scores and gait parameters were only moderately correlated (Spearman's r=0.33-0.51).INTERPRETATION:In a cohort of patients undergoing total hip arthroplasty, pre-operative differences in mean WOMAC function scores and gait parameters between low and high function subgroups disappeared by 3 months post-operatively. Gait parameters only improved significantly during the first 3 post-operative months in patients with a low pre-operative function, highlighting the importance of investigating relative changes rather than the absolute changes and the need to consider patients with high and low functions separately.

With increasing age, there may be a decrease in femoral blood flow. In some patients, this may result in local ischaemia, which subsequently may lead to local degenerative changes. Consequently, bone blood flow may play an important role in the aetiology of osteoarthritis of the hip. Little is known about bone blood flow in the femoral head of patients with advanced hip osteoarthritis. The purpose of this study was to evaluate bone blood flow and metabolism in vivo in patients with osteoarthritis of the hip. Ten patients with symptomatic osteoarthritis of the hip were enrolled prospectively. Femoral bone blood flow and metabolism were measured using positron emission tomography together with H₂(15)O and [(18)F]fluoride, respectively. Blood flow was 0.054 ± 0.032 mL cm(-3) min(-1) and 0.041 ± 0.012 mL cm(-3) min(-1) in symptomatic and contralateral femoral heads, respectively (p = 0.435). The net flux of fluoride from plasma to bone mineral (K i ) was significantly (p = 0.027) higher in the femoral head of the osteoarthritic hip (0.022 ± 0.012 mL cm(-3) min(-1)) than in that of the contralateral hip (0.007 ± 0.005 mL cm(-3) min(-1)). This study showed significant increase in bone metabolism in the proximal femur of patients with symptomatic osteoarthritis of the hip joint. There was no evidence of decreased blood flow.

In clinical practice, it is increasingly important to assess patients' daily functionality routinely and objectively. Acceleration-based gait analysis (AGA) has shown to be reliable and technically suitable for routine clinical use outside the laboratory. This study investigated the suitability of AGA for measuring function in orthopaedic patients with symptomatic gonarthrosis listed for total knee arthroplasty (TKA) by investigating (a) the ability of AGA to distinguish patients from healthy subjects, (b) the sensitivity to gait changes of AGA in assessing recovery following total knee arthroplasty in a subpopulation, and (c) correlations between AGA parameters and clinical scales. Gait was assessed using AGA in 24 patients with symptomatic gonarthrosis listed for TKA, and in 24 healthy subjects. AGA parameters (e.g. speed, asymmetry) and clinical scales (e.g. KSS) were used to monitor progress in 12 patients 3 months after TKA. The Mann-Whitney-U test, Receiver Operating Characteristic (ROC) curves, repeated measurement ANOVA and Pearson correlations were performed. AGA differentiated pathological from healthy gait. The area under the ROC curve, sensitivity and specificity values were high for speed, step frequency and step length. Different recovery profiles were found, with clinical scales showing faster recovery rates. None or only weak correlations were found between AGA and clinical scores. AGA was found to be of clinical relevance in identifying and monitoring patients with symptomatic gonarthrosis in orthopaedic practice, providing objective and additional information about function beyond clinical scales. This, together with the fact that AGA can be applied routinely, suggests the suitability of AGA for use in rehabilitation programs.

OBJECTIVE: : The aim of this study was to investigate the ability of acceleration-based gait analysis to differentiate between normal gait and different simulated functional knee limitations of increasing severity. DESIGN: : Gait of 48 healthy subjects was measured under four different walking conditions. Gait parameters (e.g., speed and asymmetry) were derived from trunk accelerations. Subjects walked a 20-m distance under four conditions: normal, simulated limited knee extension, simulated limited knee flexion, and simulated arthrodesis. The functional knee limitations were simulated using an adjustable knee brace on the right leg. RESULTS: : Acceleration-based gait analysis detected acute gait changes (i.e., speed, step length, step duration, cadence, vertical displacement, asymmetry, and irregularity) during the simulated functional knee limitations with high repeatability. The degree of change depended on the severity of the limitation, with the more severe limitations producing bigger changes in gait and the relative changes comparing well with literature values measured with laboratory-based motion analysis. CONCLUSIONS: : Acceleration-based gait analysis is sensitive for different walking conditions. The easy and fast use, the production of objective gait characteristics, and the ability to differentiate functional knee limitations suggest its suitability for clinical rehabilitation.

Objectives: The curriculum of the new post-graduate medical training program in the Netherlands is comprised of seven competencies that residents should possess upon graduation. In this new curriculum however, the competency as manager receives relatively little attention. In this preliminary study we investigated the residents’ need for management training and tried to identify the preferred form of intervention to develop these management skills. Methods: A survey was designed to investigate the perceived needs of residents for management training and the preferred form of training intervention. A total of 506 residents in four Dutch teaching hospitals were invited to participate in a web-based survey. Results were using descriptive statistics, Chi-square tests and Fisher’s exact tests. Results: A total of 177 residents responded to the survey. Of the respondents, 85% (n=146) reported a need for management training. The preferred management topics included negotiation skills, practice partnerships, knowledge of the health care system and career planning. The preferred training method was a workshop given by medical specialists or extramural content experts. The best timing for training was determined to be during residency. Conclusions: Dutch medical residents reported a need for management training. While this study justifies an intervention for training management skills in residents, more research is required to design appropriate programs that consider the preferences of residents.

We have investigated the accuracy of the templating of digital radiographs in planning total hip replacement using two common object-based calibration methods with the ball placed laterally (method 1) or medially (method 2) and compared them with two non-object-based methods. The latter comprised the application of a fixed magnification of 121% (method 3) and calculation of magnification based on the object-film-distance (method 4). We studied the post-operative radiographs of 57 patients (19 men, 38 women, mean age 73 years (53 to 89)) using the measured diameter of the prosthetic femoral head and comparing it with the true value. Both object-based methods (1 and 2) produced large errors (mean/maximum: 2.55%/17.4% and 2.04%/6.46%, respectively). Method 3 applying a fixed magnification and method 4 (object-film-distance) produced smaller errors (mean/maximum 1.42%/5.22% and 1.57%/4.24%, respectively; p < 0.01). The latter results were clinically relevant and acceptable when planning was allowed to within one implant size. Object-based calibration (methods 1 and 2) has fundamental problems with the correct placement of the calibration ball. The accuracy of the fixed magnification (method 3) matched that of object-film-distance (method 4) and was the most reliable and efficient calibration method in digital templating.

It is becoming increasingly important to evaluate surgical procedures beyond pain relief and implant survival. Patient satisfaction and objective functional assessment is now as relevant. The aim of this study was to establish the functional differences and patient perceptions between unicompartmental knee replacement (UKR) and total knee replacement (TKR). In a prospective study 52 TKR patients were compared to 24 UKR (at preoperative, 3, 6 months and 1 year postoperative). The disease specific KSS and Womac (pain and function subscores), the generic SF36 (pain, function and patient perception subscores) and the Dynaport®Knee Test, a validated performance-based knee test using accelerometers to score function during activities of daily living, was utilized. Preoperative UKR patients had significantly higher KSS function and the Dynaport®Knee Test (P < 0.05), but despite being younger, with different indication, they were not different to TKR with regards to function and pain subscores of Womac and SF36. Regarding preoperative perception, UKR patients reported better physical and social function but subjectively felt worse than TKR patients regarding health, emotion and mental status (n.s.). At one year, postoperative perception scores for both groups increased significantly, with UKR retaining functional lead and UKR patients also felt superior regarding health, emotion and mental status (n.s.). Postoperative recovery regarding KSS, Womac, and SF36-pain was steep only during the first 3 months with near equal values for both TKR and UKR. It was found that SF36-Function recovery was not significant, but UKR also scored higher than TKR. Only functional scores by the Dynaport®Knee Test showed continued improvement and maintained the functional advantage of UKR patients throughout recovery. UKR and TKR patients have different age demographics, indications and perceptions, but clinical outcome scores do not equally capture these differences, especially with regards to function. Postoperative functional benefits of UKR seem to be due mainly to the superior preoperative conditions. Appreciation of recovery with generic, disease specific and functional measurements appears invaluable.

INTRODUCTION: Whether to resurface the patella or not in total knee arthroplasty still remains undecided. Classical scores and questionnaires might not be responsive or demanding enough. This study used two accelerometer based systems to study the hypothesis whether performance based tests are able to detect a difference in patients with or without a resurfaced patella. METHOD: In this retrospective study 53 patients were included and divided into a resurfaced group (n = 31) and a non-resurfaced group (n = 22). Both groups were matched on age and longevity of follow up. Patients were clinically assessed using the Knee Society Score (KSS) at various time points. At final follow up patients were also assessed once using the Dynaport((R)) Knee Test and the Minimod((R)) Gait Test. RESULTS: The Dynaport((R)) Knee Test showed a significant functional advantage for patients with a resurfaced patella [44 vs. 39.7 (P = 0.042)], whereas KSS and The Minimod((R)) were not significant (P values ranging from 0.07 to 0.75). Similar to other reports in literature, using the KSS, it was not possible to identify significant difference between patella resurfacing or retaining in total knee arthroplasty, however using a performance based test it was possible to determine significant difference. The found advantage of patella resurfacing may be less due to pain relief but due to a functional benefit during demanding motion tasks. This finding indicates that current measurement tools may not be accurate or specific enough to detect this difference. Therefore, we recommend complementing the classic evaluation tools with an objective functional test, when conducting a randomized trial to answer the indecision whether to resurface the patella or not.

To evaluate bone blood flow and bone formation in patients after total hip revision surgery with impacted bone grafting using H2 15O and [18F]fluoride positron emission tomography (PET). To asses bone blood flow and bone metabolism in bone allograft after impaction grafting, four patients treated with total hip revision surgery were enrolled prospectively in this study. Six patients scheduled for primary hip arthroplasties were included as a control group. The study protocol consisted of three H2 15O and [18F]fluoride PET scans in each patient. Bone blood flow increased significantly compared to the preoperative state in patients treated for primary hip arthroplasty. In patients undergoing revision surgery, bone blood flow was twofold to threefold higher compared to the preoperative state, but did not reach significance. Bone metabolism in patients undergoing revision was threefold higher 2 weeks postoperatively compared to the primary hip group. We found a significant correlation between Ki and bone blood flow. Allogeneic bone grafts induce a higher rate of local periprosthetic bone formation compared to periprosthetic bone formation after a primary total hip placement. In vivo coupling between bone blood flow and bone metabolism suggests that bone metabolism in allogeneic bone grafts may partly rely on bone blood flow adaptations.

This meta-analysis was performed to summarize and compare the diagnostic performance and diagnostic accuracy of radiographic and scintigraphic techniques in the evaluation of patients suspected of having aseptically loose acetabular components. Twenty-eight studies, published between January 1975 and October 2004, presented sufficient data for quantitative analysis. The pooled sensitivity and specificity rates for plain radiography were 70% (95% confidence interval [CI] = 59%-79%) and 80% (95% CI = 73%-86%), respectively; those for subtraction arthrography were 89% (95% CI = 84%-93%) and 76% (95% CI = 68%-82%), respectively; and those for nuclear arthrography were 87% (95% CI = 57%-97%) and 64% (95% CI = 40%-82%), respectively. Finally, bone scintigraphy had a sensitivity of 67% (95% CI = 57%-76%) and a specificity of 75% (95% CI = 64%-83%). We found a significantly higher sensitivity for subtraction arthrography as compared with plain radiography and bone scintigraphy. Therefore, subtraction arthrography is recommended for use as an additional diagnostic technique when plain radiography is found to be inconclusive.

In literature no reports appear on functional recovery of unicompartmental knee replacement using both subjective and objective methods. Functional aspects are especially of importance, since prosthetic replacement is considered more often in younger patients, who require an optimal knee function for activities such as sports. In a prospective study on 38 patients with a mean age of 62.2 years functional improvement was measured. Using Knee Society Score (KSS) as a clinician based score and the Dynaport® Knee Test as a functional test measurements were performed at preoperative, 3 and 6 months, 1 and 2 years, after surgery. The Dynaport® Knee Test is an accelerometer-based system that objectively measures functional aspects of gait during various tasks of daily life. It consists of four sub scores. The KSS assesses pain and function. Both scores range from 0 to 100. The mean KSS preoperative was 44.0 and improved significantly to 81.7 at 3 months (P < 0.001) and to 87.4 (P = 0.025) at 6 months. No significant differences were noted after 6 months. The mean preoperative Dynaport® Knee Test score was 35.8 and at 3 months 43.6 (P < 0.001), 48.6 at 6 months (P < 0.001). No significant differences were noted after 6 months follow-up. Of the Dynaport sub scores, the low demanding tasks Lift and Move and Locomotion, cease to improve beyond 6 months. The high demanding task Transfers only improved up to 3 months. However, the other high demanding tasks Rise and Descend showed improvement beyond 1 year after surgery, since the improvement from 6 months to 2 years was significant (P = 0.023). This study has found that functional recovery continues beyond 6 months and even up to 2 years. It seems only more challenging tests can discriminate on improvement beyond a point where questionnaires cease to improve. The use of objective measurement methods is advocated next to the clinician based scores and self reported questionnaires.

We reviewed the results of 71 revisions of the acetabular component in total hip replacement, using impaction of bone allograft. The mean follow-up was 7.2 years (1.6 to 9.7). All patients were assessed according to the American Academy of Orthopedic Surgeons (AAOS) classification of bone loss, the amount of bone graft required, thickness of the graft layer, signs of graft incorporation and use of augmentation. A total of 20 acetabular components required re-revision for aseptic loosening, giving an overall survival of 72% (95% CI, 54.4 to 80.5). Of these failures, 14 (70%) had an AAOS type III or IV bone defect. In the failed group, poor radiological and histological graft incorporation was seen. These results suggest that impaction allografting in acetabular revision with severe bone defects may have poorer results than have previously been reported.

An inertial measurement unit (IMU) allows kinematic evaluation of human motion with fewer operational constraints than a gold standard optoelectronic motion capture (MOCAP) system. The study's aim was to compare IMU and MOCAP measurements of dynamic pelvic orientation angles during different activities of daily life (ADL): gait, sit-to-stand (STS) transfers and block step-up (BS) transfers. A single IMU was attached onto the lower back in seventeen healthy participants (8F/9 M, age 19-31 years; BMI < 25) and optical skin markers were attached onto anatomical pelvic landmarks for MOCAP measurements. Comparisons between IMU and MOCAP by Bland-Altman plots demonstrated that measurements were between 2SD of the absolute difference and Pearson's correlation coefficients were between 0.85 and 0.94. Frontal plane pelvic angle estimations achieved a RMSE in the range of [2.7 degrees -4.5 degrees ] and sagittal plane measurements achieved a RMSE in the range of [2.7 degrees -8.9 degrees ] which were both lowest in gait. Waveform peak detection times demonstrated ICCs between 0.96 and 1.00. These results are in accordance to other studies comparing IMU and MOCAP measurements with different applications and suggest that an IMU is a valid tool to measure dynamic pelvic angles during various activities of daily life which could be applied to monitor rehabilitation in a wide variety of musculoskeletal disorders.

Physical functioning is a multidimensional construct covering perceived functioning, functional capacity and actual physical activity. Currently, the assessment of physical functioning in low back pain (LBP) patients has been limited to only one or two of these aspects. This study evaluates physical functioning of LBP patients by assessing the three individual aspects using questionnaires and ambulant sensor-based measurements.Actual physical activity, functional capacity and perceived functioning were measured in 26 patients undergoing patient specific treatment before, direct and 3-4 weeks after the first treatment using, respectively, sensor-based activity monitoring, sensor-based motion analysis test and the Oswestry questionnaire. Patients were compared to a healthy control group.Perceived functioning and functional capacity, but not actual physical activity is impaired in pre-treatment LBP patients. After treatment, patients improved in perceived physical functioning and functional capacity approaching healthy levels, however only slight (p 0.05) improvements in actual physical activity were found. Moreover, only few and weak correlations were found between the different aspects of physical functioning.Perceived functioning, actual physical activity and functional capacity are three independent outcome dimensions, being complementary but not redundant. Especially, perceived functioning and physical capacity need attention when evaluating LBP patients during rehabilitation. Implications for Rehabilitation Perceived physical functioning and physical capacity are negatively affected by low back pain and improve after treatment. Low back pain patients perform their daily activity independent of pain and complaints. Inertia sensor-based motion analysis can objectify treatment effects showing low back pain patients their progress in rehabilitation. New interventions can be justified with inertia sensor technology in low back pain patients.

Recently it was shown that the design changes from the ABG-I to ABG-II hip stem resulted in a better, although not significant, proximal bone preservation. Our hypothesis was that by matching patients for preoperative bone quality, statistical power would increase and that the trend of better proximal bone preservation in ABG-II might become significant. Twenty-four ABG-II patients were compared to two different ABG-I groups: (1) 25 patients from our earlier prospective study and (2) a group of 24 patients selected to perfectly match the ABG-II group regarding gender, age and preoperative bone quality. Postoperative changes in periprosthetic bone mineral density (BMD) were quantified at 2 years postoperatively using DEXA scanning. Bone preservation (less BMD loss) was better for the ABG-II than the ABG-I (all two groups) in the proximal zones 1 and 7. In Gruen zone 7, a statistically significant difference was found for group B (p = 0.03). By matching patients for preoperative bone quality and gender, a statistical significant difference was found in proximal bone preservation in favour of ABG-II. In future comparative bone remodelling studies using DEXA, patients should be matched for preoperative bone quality and gender.

UNLABELLED Proximal bone resorption and an increased fracture rate in the ABG-I stem has been shown. For these reasons the ABG-I stem design was changed to the ABG-II. In this study periprosthetic bone loss around the ABG-I vs ABG-II is compared to verify if the design changes resulted in improved proximal bone preservation. METHODS 51 patients were randomised to either the ABG-I or ABG-II hip prosthesis. Periprosthetic BMD change at various time points was measured using DEXA. Between the two groups (age, gender, weight etc.) no statistical difference was encountered. Compared to the baseline at two years the ABG-II preserved bone better proximally (e.g. zone 7: ABG-II: -3.7%, ABG-I: -11.9%, p=0.05) than the ABG-I. Distally, the trend was opposite and less bone loss was measured for the ABG-I than the ABG-II in zones 3, 4 and 5 (n.s.). CONCLUSION this study confirms the philosophy behind the design changes from the ABG-I to ABG-II stem where increased elasticity, more proximal HA-coating, a shorter and distally polished stem, were meant to reduce proximal bone resorption. In future this may lead to fewer periprosthetic fractures and to less complicated revision surgery.

Background Outcome assessment of total knee arthroplasty (TKA) by subjective patient reported outcome measures (PROMs) may not fully capture the functional (dis-)abilities of relevance. Objective performance-based outcome measures could provide distinct information. An ambulant inertial measurement unit (IMU) allows kinematic assessment of physical performance and could potentially be used for routine follow-up. Aim To investigate the responsiveness of IMU measures in patients following TKA and compare outcomes with conventional PROMs. Methods Patients with end stage knee OA (n = 20, m/f = 7/13; age = 67.4 standard deviation 7.7 years) were measured preoperatively and one year postoperatively. IMU measures were derived during gait, sit–stand transfers and block step-up transfers. PROMs were assessed by using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee Society Score (KSS). Responsiveness was calculated by the effect size, correlations were calculated with Spearman's rho correlation coefficient. Results One year after TKA, patients performed significantly better at gait, sit-to-stand transfers and block step-up transfers. Measures of time and kinematic IMU measures demonstrated significant improvements postoperatively for each performance-based test. The largest improvement was found in block step-up transfers (effect size = 0.56–1.20). WOMAC function score and KSS function score demonstrated moderate correlations (Spearman's rho = 0.45–0.74) with some of the physical performance-based measures pre- and postoperatively. Conclusion To characterize the changes in physical function after TKA, PROMs could be supplemented by performance-based measures, assessing function during different activities and allowing kinematic characterization with an ambulant IMU.

Roorda LD, Roebroeck ME, van Tilburg T, Molenaar IW, Lankhorst GJ, Bouter LM, and the Measuring Mobility Study Group. Measuring activity limitations in walking: development of a hierarchical scale for patients with lower-extremity disorders who live at home. Objective To develop a hierarchical scale that measures activity limitations in walking in patients with lower-extremity disorders who live at home. Design Cross-sectional study. Setting Orthopedic workshops and outpatient clinics of secondary and tertiary care centers. Participants Patients (N=981; mean age ± standard deviation, 58.6±15.4y; 46% men) living at home, with different lower-extremity disorders: stroke, poliomyelitis, osteoarthritis, amputation, complex regional pain syndrome type I, and diabetic and degenerative foot disorders. Interventions Not applicable. Main Outcome Measures (1) Fit of the monotone homogeneity model, indicating whether items can be used for measuring patients; (2) fit of the double monotonicity model, indicating invariant (hierarchical) item ordering; (3) intratest reliability, indicating repeatability of the sum score; (4) robustness, addressing the clinimetric properties within subgroups of patients; and (5) differential item functioning, addressing the validity of comparisons between subgroups of patients. Results Thirty-five of 41 dichotomous items had (1) good fit of the monotone homogeneity model (coefficient H =.50), (2) good fit of the double monotonicity model (coefficient H T =.33), (3) good intratest reliability (coefficient ρ=.95), (4) satisfactory robustness (within subgroups of patients defined by age, sex, and diagnosis), and (5) some differential item functioning (6 items in amputees compared with nonamputees). Conclusions A hierarchical scale, with excellent scaling characteristics, was developed to measure activity limitations in walking in patients with lower-extremity disorders who live at home. The measurements should be interpreted cautiously when making comparisons between amputees and nonamputees.

Objective: To summarize and compare the diagnostic accuracy of contrast and subtraction arthrography in the assessment of aseptic loosening of total hip arthroplasties. Design: This meta-analysis was performed using methods described by the Cochrane Methods Group on Systematic Reviews of Screening and Diagnostic Tests. We included original, English-language papers published between January 1975 to October 2004 that examined contrast-enhanced arthrography with or without subtraction for diagnosis of loosening of total hip prostheses. A qualitative and quantitative analysis was performed by two investigators. Results: With regard to the acetabular component, pooled sensitivity and specificity for contrast arthrography was 70% (95% confidence interval, 52–84) and 74% (95% CI, 53–87), respectively. Subtraction arthrography had a significantly higher sensitivity of 89% (95% CI, 84–93) (p = 0.01), with a similar specificity of 76% (95% CI, 68-82). For the femoral component, pooled sensitivity and specificity for contrast arthrography were 63% (95% CI, 53–72) and 78% (95% CI, 68–86). Pooled estimates for subtraction arthrography revealed a significantly higher sensitivity of 86% (95% CI, 74–93) (p = 0.003). Specificity was 85% (95% CI, 77–91) and was similar to the data of contrast arthrography (p = 0.23). Conclusion: Using the present data we found that the subtraction arthrography is a sensitive technique for detection of loosening of total hip prostheses, offering added value over contrast arthrography, especially for evaluation of the femoral component.

Impacted morselized donor bone is successfully used to treat bone loss in revision total hip arthroplasties. It is generally thought, but not proven, that the processing and storage at -80 degrees C of the donor bone kills all cells. Because of the risk of contamination and to increase our understanding about the process of new bone formation after revision total hip arthroplasty, the aim of this study was to investigate whether the donor bone does contain vital cells. Samples from 11 femoral heads were obtained according to the American and European standards of bone banking, and tested for their capacity to give rise to proliferating cells, using tissue culture methods. All bone samples were stored at - 80 degrees C for a minimum of 6 months. Bone sample cores were morselized and cultured for 6 weeks. Inverted phase contrast microscopy was used to evaluate cell growth. DNA marker analysis was used to confirm cellular identity. All bank bone samples gave rise to cell growth. The cell cultures showed osteoblastic characteristics in that they expressed high levels of alkaline phosphatase activity. DNA marker analysis showed identical alleles for cultured cells from frozen bone and freshly obtained buccal cells from the same donor, indicating that the cells growing from the banked bone were indeed originating from the donor tissue. It was therefore concluded that -80 degrees C freezing of bone tissue does not routinely kill cells within the tissue.

Impacted morsellised allografts have been used successfully to address the problem of poor bone stock in revision surgery. However, there are concerns about the transmission of pathogens, the high cost and the shortage of supply of donor bone. Bone-graft extenders, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), have been developed to minimise the use of donor bone. In a human cadaver model we have evaluated the surgical and mechanical feasibility of a TCP/HA bone-graft extender during impaction grafting revision surgery. A TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability when compared with bone graft alone. The implications of the use of this type of graft extender in impaction grafting revision surgery are discussed.

J Bone Joint Surg [Br] 2005;87-B:267-71. Received 1 July 2003; Accepted after revision 11 February 2004 Impacted morsellised allografts have been used successfully to address the problem of poor bone stock in revision surgery. However, there are concerns about the transmission of pathogens, the high cost and the shortage of supply of donor bone. Bone-graft extenders, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), have been developed to minimise the use of donor bone. In a human cadaver model we have evaluated the surgical and mechanical feasibility of a TCP/HA bone-graft extender during impaction grafting revision surgery. A TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability when compared with bone graft alone. The implications of the use of this type of graft extender in impaction grafting revision surgery are discussed.

Radiographs of 72 uncemented hip implants with a mean follow-up of 6.5 years were analysed to measure wear of the implant. The wear rate was measured using the modified technique of Livermore and was found to be 0.13 mm per year (CI 95% 0.080–0.18). There was no statistical correlation between wear and age, gender and cup angle, but there was a correlation between wear and the number and size of cysts. This has not been previously published. In view of the risk of loosening and of a dramatic increase in the rate of wear when the femoral head articulates with the metal backing, it is important to plan revision of these cups in good time and to ensure regular radiographic surveillance of these patients.

Item does not contain fulltext OBJECTIVE: Biological repair of femoral bone loss using bone impaction grafting. Reconstruction of the centre of rotation of the hip using a cemented stem, the size and offset of which are at the discretion of the surgeon. INDICATIONS: Femoral implant loosening with bone loss. CONTRAINDICATIONS: Infection, neurological disorders, noncompliant patient. SURGICAL TECHNIQUE: Extraction of the loose femoral implant, cortical reconstruction using meshes if required, impaction bone grafting with special instruments, cement fixation of a polished tapered stem. POSTOPERATIVE MANAGEMENT: Individualized period of bed rest and limited weight bearing. RESULTS: Impaction bone grafting and a cemented polished stem were used to perform 33 femoral reconstructions. After a mean follow-up of 15 years, no femoral reconstruction had to be revised. One unrecognized intraoperative fracture healed after nonsurgical treatment, three postoperative femoral fractures healed after plate fixation with the stem left in situ. The average Harris Hip Score improved from 49 prior to surgery to 85 points thereafter. Kaplan-Meier analysis with femoral revision for any reason as the end point showed a survival rate of 100 %.