No abstract

The dart thrower's motion is a wrist rotation along an oblique plane from radial extension to ulnar flexion. We report an in-vivo study to confirm the use of the dart thrower's motion during activities of daily living. Global wrist motion in ten volunteers was recorded using a three-dimensional optoelectronic motion capture system, in which digital infra-red cameras track the movement of retro-reflective marker clusters. Global wrist motion has been approximated to the dart thrower's motion when hammering a nail, throwing a ball, drinking from a glass, pouring from a jug and twisting the lid of a jar, but not when combing hair or manipulating buttons. The dart thrower's motion is the plane of global wrist motion used during most activities of daily living. Arthrodesis of the radiocarpal joint instead of the midcarpal joint will allow better wrist function during most activities of daily living by preserving the dart thrower's motion.

Background: Low back pain (LBP) classification systems are used to deliver targeted treatments matched to an individual profile, however, distinguishing between different subsets of LBP remains a clinical challenge. Methods: A novel application of the Cardiff Dempster-Shafer Theory Classifier was employed to identify clinical subgroups of LBP on the basis of repositioning accuracy for subjects performing a sitting and standing posture task. 87 LBP subjects, clinically subclassified into flexion (n = 50), passive extension (n = 14), and active extension (n = 23) motor control impairment subgroups and 31 subjects with no LBP were recruited. Thoracic, lumbar and pelvic repositioning errors were quantified. The Classifier then transformed the error variables from each subject into a set of three belief values: (i) consistent with no LBP, (ii) consistent with LBP, (iii) indicating either LBP or no LBP. Findings: In discriminating LBP from no LBP the Classifier accuracy was 96.61%. From no-LBP, subsets of flexion LBP, active extension and passive extension achieved 93.83, 98.15% and 97.62% accuracy, respectively. Classification accuracies of 96.8%, 87.7% and 70.27% were found when discriminating flexion from passive extension, flexion from active extension and active from passive extension subsets, respectively. Sitting lumbar error magnitude best discriminated LBP from no LBP (92.4% accuracy) and the flexion subset from no-LBP (90.1% accuracy). Standing lumbar error best discriminated active and passive extension from no LBP (94.4% and 95.2% accuracy, respectively). Interpretation: Using repositioning accuracy, the Cardiff Dempster-Shafer Theory Classifier distinguishes between subsets of LBP and could assist decision making for targeted exercise in LBP management.

Despite the high number of total hip arthroplasty (THA) procedures performed each year, there is no common consensus on the best surgical approach. Gait is known to improve following THA although it does not return to what is typically quantified as normal, and surgical approach is believed to be a contributing factor. The current study evaluates postoperative hip function and provides an objective assessment following two common surgical approaches: the McFarland-Osborne direct lateral and the southern posterior. Faced with the common problem of providing an objective comparison from the wealth of data collected using motion analysis techniques, the current study investigates the application of an objective classification tool to provide information on the effectiveness of each surgery and to differentiate between the characteristics of hip function following the two approaches. Seven inputs for the classifier were determined through statistical analysis of the biomechanical data. The posterior approach group exhibited greater characteristics of non-pathological gait and displayed a greater range of functional ability as compared with the lateral approach cohort. The classification tool has proved to be successful in characterizing non-pathological and THA function but was insufficient in distinguishing between the two surgical cohorts.

No abstract

The purpose of this study is to assess changes in subjective and objective function from pre- to post-knee arthroplasty (KA) using a combined classifier technique. Twenty healthy adults (50-80 years) and 31 KA patients (39-81 years) were studied (4 weeks pre- and 6 months post-KA). Questionnaire measures of subjective pain, joint stability, activity and function were collected. Objective functional assessment included goniometry, ultrasound imaging and 3-D motion analysis/inverse modelling of gait and sit-stand. An optimal set of variables were used to classify function using the Cardiff Dempster-Shafer theory (DST) method. Out of sample accuracy of the classifiers ranged between 90% and 94% for segregating healthy individuals and pre-KA patients. Post-KA subjective function improved with 74% classified as healthy. However, there was minimal improvement in objective measures (23% classified as healthy). The novel use of Cardiff DST segregated KA patients from healthy individuals and estimated changes in function from pre- to post-surgery. KA patients had improved pain and function post-operation but objective knee joint measures remained different to healthy individuals.

HighlightsJoint loading and function was assessed bilaterally in unilateral knee OA.Gait data can be summarised using a functional classification approach.Gait abnormailities in knee OA and following arthroplasty are relatively symmetrical.Joint loading and function frequently remains abnormal following arthroplasty.Pre-operative function (the Cardiff Classifier) can predict post-operative function.

Our motion analysis study found the Aspen collar to be superior to the other collars when measuring restriction of movement of the cervical spine in all planes, particularly the sagittal and transverse planes, while the Aspen Vista was the least effective collar.