Anteroposterior glide versus rotating platform low contact stress (LCS) knee arthroplasty: a randomised controlled trial.

BACKGROUND: Fifty thousand knee replacements are performed annually in the UK at an estimated cost of pound 150 million. Post-operative improvement depends on a number of factors including implant design and patient associated factors. To our knowledge there are no published study's comparing the results of AP glide and rotating platform designs of LCS knee arthroplasty. Therefore we feel that a study is required to investigate and compare the effects of two types of LCS total knee arthroplasty on joint proprioception and range of motion. METHODS/DESIGN: Patients will be randomised to receive either a LCS AP glide or Rotating platform prosthesis. Clinical scores (Oxford knee score, American knee society score, EuroQol), range of motion and proprioception will be assessed prior to and at 3,6, 12 and 24 months after the operation. Proprioception will be assessed in terms of absolute error angle (mean difference between the target angle and the response angle). Knee angles will be measured in degrees using an electromagnetic tracking device, Polhemus 3Space Fastrak that detects positions of sensors placed on the test limb. Student's t-test will be used to compare the mean of two groups. DISCUSSION: Evidence is lacking concerning the best prosthesis to use for patients undergoing total knee replacement. This pragmatic randomised trial will test the null hypothesis that anteroposterior glide LCS knee arthroplasty does not result in better post operative knee motion and proprioception as compared to rotating platform LCS knee.

Can posture analysis point towards curve progression in scoliotic subjects?

Previous research employing biomechanical measurement has demonstrated asymmetries in kinematics and kinetics. Similar asymmetries have been reported from anthropometric studies. These findings suggest that asymmetry may play an important aetiological role in adolescent idiopathic scoliosis (AIS). The present study is a part of a wider comprehensive investigation aimed at identifying asymmetries in lower limb kinematics and pelvic and back movements during level walking in a sample of scoliotic subjects. Such asymmetries may be related to the spinal deformity. While previous studies indicate that force platform measurements provide a good estimation of the static balance of individuals, there remains a paucity of information on dynamic balance during walking. There is published evidence on the use of Centre of Pressure (CoP) and net joint moments in gait assessment. Although these investigations have assessed Centre of Mass (CoM)-CoP distance relationships in clinical conditions, there is a paucity of data relating to the moments about CoM. An objective of the present study was to assess and establish the asymmetry in the CoP pattern and moments about CoM during level walking and its relationship to spinal deformity. Results indicate differences across the subjects depending on the laterality of the major curve. Furthermore, the results indicate that the variables identified in this study could be applied to initial screening and surgical evaluation of scoliosis and other spinal deformities. Further studies are being undertaken to validate these findings.

The short term effects of a single corticosteroid injection on the range of motion of the shoulder in patients with isolated acromioclavicular joint arthropathy.

This study is aimed at evaluating the short-term effects of a single corticosteroid injection of the acromioclavicular joint on the range of motion of the shoulder joint using a three dimensional electromagnetic tracking system (FASTRAK) in patients with isolated unilateral acromioclavicular joint (ACJ) arthropathy. Eighteen patients (16 male, 2 female; mean age: 47.53 years), with isolated unilateral ACJ arthropathy were included in the study. Injection of the symptomatic ACJ with local anaesthetic and corticosteroid was performed under image intensifier guidance. Bilateral shoulder FASTRAK assessment before and two weeks after injection of the symptomatic ACJ was performed, measuring flexion/extension, anatomical abduction, scapular abduction and horizontal cross body adduction. Pain was measured using a visual analogue scale. There was a significant difference in the range of movement between the symptomatic and asymptomatic shoulder before the injection (p < 0.01). Range of extension and pain score of the symptomatic shoulder improved significantly (p < 0.05 and p < 0.001, respectively) after the injection. In patients with radiographical evidence of degenerative ACJ disease, there was also significant improvement in the range of horizontal flexion (p < 0.05). Injection of the ACJ with local anaesthetic and corticosteroid was found to produce short-term pain relief and partial improvement in the range of movement. FASTRAK is useful in the measurement and documentation of range of motion, and can be used to assess the treatment outcome in patients with isolated ACJ arthropathy.

Movement analysis of scoliotic subjects using Fastrak.

An attempt has been made to simplify the measurement of composite movement involving abnormal rotation in scoliosis, which is considered to have an important role in the diagnosis and treatment of the condition. Analysis of three-dimensional movement provides pertinent information concerning the morphological description of scoliotic deformities. The description of this movement is of clinical interest for aiding diagnosis and/or prognosis of spinal deformity evolution. Previous studies have indicated that idiopathic scoliosis is a three-dimensional deformity accompanied by a generalised torsion phenomenon and attempts have been made to associate the geometric torsion index with the curvi-linear shape of idiopathic scoliosis. Although previous investigations have documented the three-dimensional reconstruction of scoliotic spine, most methods either expose the subject to a high level of radiation, as in stereo-radiographs, or demand a high degree of technical input and time, as in video based gait analysis systems. This study employs an electro magnetic field capturing system (FASTRAK) to estimate the spinal movements. This simple system is inexpensive and highly portable. Furthermore, it can give instant graphic and numerical values of the composite movement. The results of this study indicate the usefulness this system in the diagnosis of scoliosis and highlights the possibility of its uses in screening school children and other surveys.

Kinematic differences in lower limb gait analysis of scoliotic subjects.

Although various factors have been attributed to the etiology of idiopathic scoliosis, studies have indicated that the kinematic differences in the spine, pelvis and lower limb may contribute to the causation and progression of idiopathic scoliosis. The aim of this investigation was to identify asymmetries in lower limb kinematics and pelvic and back movements during level walking in scoliotic subjects that can be related to the spinal deformity. The study has employed a movement analysis system to estimate various joint angles in the lower extremities and other kinematic parameters in the pelvis and back. The results of a pilot study have highlighted the potential usefulness of a range of parameters in the indication of asymmetries and their implications for spinal deformity generation. While demonstrating the value that movement analysis systems may have in investigating pathogenesis and aetiology, these preliminary findings indicate that the identified variables can also used in the kinematic analysis of spinal deformities such as scoliosis. Further studies are being undertaken to validate these findings.

Clinical results and motion analysis following arthroscopic anterior stabilization of the shoulder using bioknotless anchors.

PURPOSE: Traumatic anterior dislocation of the shoulder is a common occurrence increasingly being treated arthroscopically. This study aims to determine the outcome of arthroscopic anterior stabilization using bioknotless anchors and analyze the motion in a subset of these patients. MATERIALS AND METHODS: The outcome of 20 patients who underwent arthroscopic anterior stabilization using the bioknotless system was studied (average follow-up 26 months). Four of these patients underwent motion analysis of their shoulder pre- and post-operatively. RESULTS: 15% were dissatisfied following surgery and the recurrence of instability was also 15%. Those who were dissatisfied or suffered recurrent symptoms had statistically significant lower constant scores at the final follow up. Pre-operative motion analysis showed a disordered rhythm of shoulder rotation which was corrected following surgery with minimal loss of range of motion. CONCLUSIONS: Our success rate was comparable to similar arthroscopic techniques and results published in the literature. Patient satisfaction depended more on return to usual activities than recurrence of symptoms. There was very little reduction in range of movement following surgery and the rhythm of shoulder motion, particularly external rotation in abduction was improved. LEVEL OF EVIDENCE: Four retrospective series.

Assessment of the centre of pressure pattern and moments about S2 in scoliotic subjects during normal walking.

BACKGROUND CONTEXT: Research employing gait measurements indicate asymmetries in ground reaction forces and suggest relationships between these asymmetries, neurological dysfunction and spinal deformity. Although, studies have documented the use of centre of pressure (CoP) and net joint moments in gait assessment and have assessed centre of mass (CoM)-CoP distance relationships in clinical conditions, there is a paucity of information relating to the moments about CoM. It is commonly considered that CoM is situated around S2 vertebra in normal upright posture and hence this study uses S2 vertebral prominence as reference point relative to CoM. PURPOSE: To assess and establish asymmetry in the CoP pattern and moments about S2 vertebral prominence during level walking and its relationship to spinal deformity in adolescents with scoliosis. PATIENT SAMPLE: Nine Adolescent Idiopathic Scoliosis subjects (8 females and 1 male with varying curve magnitudes and laterality) scheduled for surgery within 2-3 days after data collection, took part in this study. OUTCOME MEASURES: Kinetic and Kinematic Gait assessment was performed with an aim to estimate the CoP displacement and the moments generated by the ground reaction force about the S2 vertebral prominence during left and right stance during normal walking. METHODS: The study employed a strain gauge force platform to estimate the medio-lateral and anterior-posterior displacement of COP and a six camera motion analysis system to track the reflective markers to assess the kinematics. The data were recorded simultaneously. RESULTS: Results indicate wide variations in the medio lateral direction CoP, which could be related to the laterality of both the main and compensation curves. This variation is not evident in the anterior-posterior direction. Similar results were recorded for moments about S2 vertebral prominence. Subjects with higher left compensation curve had greater displacement to the left. CONCLUSION: Although further longitudinal studies are needed, results indicate that the variables identified in this study are applicable to initial screening and surgical evaluation of scoliosis.

Fracture strain and stability with additional locking screws in intramedullary nailing: a biomechanical study.

BACKGROUND: We studied the effect of additional locking screws on fracture strain and stability in tibial intramedullary nailing. METHODS: We drilled an additional diaphyseal locking hole into 8-mm solid tibial nails 185 mm from the proximal end of the nail, and locked it proximally and distally. An osteotomy was produced 4.5 cm distal to the additional hole, and the construct loaded axially, in flexion, extension, and torsion. The nails were also tested for their fatigue strength. RESULTS: With the additional locking screw, strain increased proximally during loading in neutral and flexion. Strain decreased on loading in extension. The extra locking screw decreased strain close to the osteotomy site in all loading positions. A significant reduction in angular motion at the osteotomy site occurred with the addition of the extra locking screw. The nails survived the fatigue test, although the stress increased around the additional locking hole CONCLUSIONS: Nails with additional locking options, by altering strain and motion at the fracture site, may have the clinical potential to affect fracture healing.

Assessment of ground reaction force during scoliotic gait.

Although the causes and progression of adolescent idiopathic scoliosis (AIS) are still unclear, a recent extensive review has indicated a number of possible aetiological factors. Previous investigations, employing gait measurements, have indicated asymmetries in the ground reaction forces and suggest a relationship between these asymmetries, neurological dysfunction and spinal deformity. Using a strain-gauge force platform, the present study has examined the time-domain parameters of various components of the ground reaction force together with impulse. Symmetry indices (SI) between left and right sides have also been estimated. The results show that the patients with a left compensatory curve had a greater SI for a left-side impulse, whilst subjects with little or no compensation had a greater right-side impulse. This indicates that a possible gait compensation is occurring, so that the subjects compensate on the opposite pelvis/lower limb to that of the curve. While indicating the asymmetries between left and right, the results also serve to highlight the value of using kinetic parameters in developing the understanding of the pathogenesis and aetiology of scoliosis.