Introduction

There is limited evidence assessing the effect of the Ankle Foot Orthosis (AFO) on gait improvements in diplegic cerebral palsy. In particular, the effect of the AFO on vertical forces during gait has not been reported. Appropriate vertical ground reaction forces are crucial in enabling children with CP to walk efficiently. This study investigated the effect of AFO application on the vertical forces in gait, particularly the second vertical peak in force (FZ2) in late stance. The force data was compared with the barefoot walk.

The pattern of injury to the carpal ligaments following wrist trauma is unclear. Different imaging techniques often prove inconclusive rendering the diagnosis difficult and hence the treatment controversial. This study aimed to observe and evaluate the differences in scapholunate kinematics before and after sectioning the scapholunate interosseous ligament (SLIL) and radioscaphocapitate ligament (RSC).

Twenty two embalmed cadaveric wrists were used. There were four males and seven females with an average age of 84 years. Their medical records confirmed the absence of previous history of wrist diseases or injuries. The extensor and flexors tendons of the wrist were removed leaving the capsule intact. Two drill bits (1.5 mm) were used to make a hole each in scaphoid and lunate, one centimeter apart. The drill bits were left in the bones to act as metal wires for calibration. Each wrist was moved through a set of motions and each movement was performed thrice; first one with the ligaments intact, second with SLIL sectioned and the last one with RSC excised. Digital photographs were taken and angles measured with MB Ruler software. Analysis of variance was done using SPSS 12.

There was no angle between the metal pointers when the ligaments were intact. There was movement and change in angle detected when SLIL and RSC were sectioned. The sectioning of the SLIL lead to a significant increase in the angle between the pointers in all the movements recorded (p value < 0.001). Subsequent sectioning of the RSC further increased this angle but this increase was much smaller compared to that after sectioning SLIL. On completion of the measurements the wrist capsule was opened to reveal that both the ligaments had been successfully sectioned and there were no degenerative changes in the bones or ligaments in any wrist.

This first cadaveric evaluation of alterations in scapholunate motion with sectioning of SLIL and RSC revealed that SLIL has a significant influence on the scapholunate kinematics, where as sectioning of the RSC has little additional effect. This in-vivo finding might have implications of importance of preserving SLIL during wrist surgeries and its role in management of carpal instabilities.

Introduction: Successful shoulder arthroplasty is based on restoration of the individual’s proximal humeral morphology with a precise osteotomy of the humeral head at the level of the anatomical neck. The objective of this study was to determine the geometry of the articular portion of the humeral head in contact with the glenoid in the neutral position and compare the orientation to the geometry of the humeral head determined using the cartilage/calcar interface of the anatomical neck.

Methods: An intact rotator cuff and joint capsule were exposed for six cadaveric full arms. Precision perspex reference cubes were attached to the greater tuberosity of the humerus and to the coracoid process of the scapula on each specimen. Each shoulder was mounted in a custom built jig with the arm fixed in the neutral position and a Microscribe 3D-X digitizer used to digitize three faces of each precision cube. The shoulder joint was then disarticulated and both the humerus and scapula re-mounted on the same jig, independently. The cube faces were re-digitized and relevant points, lines and surfaces were identified and digitized on each humerus and scapula. The humeri were then scanned using a high precision surface laser scanner.

The data collected from both digitizing tools were merged into the same coordinate system and graphically represented. Paired Student’s t-tests were used to compare the inclination and retroversion angles for the two techniques.

Results and discussion: The study found a significant difference in inclination (p less than 0.02) and no difference in retroversion (p equal to 0.75) when the glenoid position was used to calculate humeral head orientation (Inclination: Mean 11.5 deg., StD. 11.2 deg.; Retroversion: Mean 20.5 deg., StD. 6.6 deg.) when compared to using the cartilage/calcar interface (Inclination: Mean 134.1 deg., StD. 1.9 deg.; Retroversion Mean 21.7 deg., StD. 13.9 deg.).

Small deviations in the recovery of head orientation in shoulder arthroplasty may impact on the longevity of an implant. The differences in inclination and retroversion noted in this study may alter the load on the glenoid and/or rotator cuff mechanism in joint replacement. Further research is necessary.

Dynamic assessment of the wrist motion and the specific angles are difficult using the conventional methods. We wanted to adapt and assess the repeatability of the Fas-trak system for continuous monitoring of three dimensional (3 D) wrist movements.

Twenty seven volunteers, aged 18 to 30 years were asked to perform predetermined tasks. The exclusion criteria were previous history of wrist trauma or joint disease. The transmitter was mounted on the dorsum of the forearm while the sensor was placed over the third metacarpal head. The protocol of three tasks was developed. Task 1 measured maximal flexion, extension, radial and ulnar deviation of the wrist. Task 2 involved picking up an object and moving it across a barrier. Task 3 involved the writing simulation. The comparison between the left and the right wrists indicated suitability of the system to be used on either of the limbs. Repeated measurements on the right wrist provided an assessment of repeatability of the Fastrak system.

The Fastrak system was successful in acquiring data in 3 D. The transmitter and the sensor were easy to attach and were of no discomfort to the subjects. As expected the maximum movement was noted in the flexion-extension plane. The total arc of movement in the flexion-extension plane was 127.1 degrees and 69.7 degrees in the radio-ulnar plane. There was no statistically signifi-cant difference between the movements in the left and the right wrists, even when the effect of dominance was considered. The lift and move task showed that most subjects utilised three-fourths of the total possible radio-ulnar movement, but only one-thirds of the total flexion and extension. The writing simulation revealed a substantial variability between subjects. The Fastrak system revealed variation up to 3 degrees in the means of range of movements, while measuring wrist movements.

The current study showed that the Fastrak system is a user-friendly and repeatable device, which could be used in everyday clinical use. It has the potential to be used for evaluation of the diseased wrist and the results of therapeutic interventions, operative or otherwise.

Introduction: Accurate recovery of humeral head geometry in shoulder arthroplasty is an important requirement for a good functional outcome. Despite this, spherical prosthetic components are implanted when the total proximal humerus is described as ovoid¹. However, 60 to 80 % of the head is spherical¹. If, in the normal glenohumeral joint, only the spherical portion is in contact with the glenoid then recovery of normal mechanics is likely with a spherical prosthetic component.

Contact patterns have been examined ex vivo² under static conditions but do not reflect the likely in vivo contact pattern under dynamic loading and have not been correlated to changes in sphericity of the articular surface. A recent study of the distal femur found that thickness of normal articular cartilage is positively correlated with loading³ and, thus, contact.

The objective of this study was to determine the feasibility of using a surface laser scanner to determine cartilage thickness and, therefore, likely contact area and to correlate changes in thickness to changes in sphericity of the articular surface.

Methods: A cadaveric arm without bony deformity or evidence of rotator cuff disease was dissected free of soft tissue and mounted on a rigid block within the frame of a surface laser scanner (Kestrel3D Ltd., UK). The articular surface of the humerus was scanned at a resolution of 200 μm. The cartilage was then dissolved away and the humerus re-scanned. The x,y,z coordinate data of the re-scanned bone were used to match the sub-chondral bone with the cartilage from the previous scan using Pointstream™ software (Kestrel3D Ltd., UK).

The cloud point data for the cartilage and bony surfaces were exported into modelling software (McNeal and Assoc., Seattle, WA) and the surface area of the head divided into ten equal sections. For each slice of both the cartilage and bony surface, the radius of curvature was calculated using a least square fit optimisation technique⁴. The differences in radius of curvature between the cartilage surface and subchondral bone surface were used to calculate the cartilage thickness for each slice. The standard deviation from the radius of curvature was used to calculate the degree of deviation from sphericity.

Results: For the first 60 % of the surface area, the deviation from sphericity was 0.5% of the radius with a cartilage thickness of 0.74 mm. The deviation from sphericity and cartilage thickness for 100% of the articular surface was > 1% and 0.63 mm, respectively.

Conclusions: The experiment proved that the surface laser scanner can be used to elucidate the relationship between contact patterns and articular curvature of the proximal humerus. The changes in sphericity concur with results from previous studies¹. Assuming cartilage thickness correlates to contact patterns at the normal glenohumeral joint, the change in cartilage thickness suggests that contact may occur only at the spherical portion of the head. Knowledge of this relationship may aid in future prosthetic design considerations or in modification of the osteotomy technique. To further support these findings, a 50μm laser scanner is being developed and will be used on a larger sample size.

Biomechanical alignment of the knee is a major determinant in the outcome of Total Knee Arthroplasty. However, the best method to assess the alignment is yet undecided. Conventional methods use hip to ankle “long” standing x-rays but these suffer from technical difficulties and hence are a potential for error. Short x-rays are considered to have doubtful accuracy.

This study aimed to assess if the “short” AP x-rays could be used to assess the lower limb axis within a range of statistically insignificant and clinically acceptable difference.

The results indicate the readings from the short x-rays were not statistically different from those obtained from the long x-rays in four sets of observations. The largest difference between any two readings was 0.68 degrees. The analysis of data showed that the measurements from the short x-rays could indeed be used to assess the long axis of the lower limb with the provison that there is no gross femoral shaft deformity.

Radiographs are often used to determine the varus/ valgus alignment of the prosthesis in relation to the long axis of femur. This is usually considered to be one of the important parameters in predicting early mechanical failure of the total hip replacement.

The measurements made by the University of Dundee X-Ray Analysis Software and skilled manual operators of the varus and valgus angulations of hip prosthesis in relation to the femoral shaft were compared for inter and intra-observer reliability.

The manual measurements were carried out on the same randomly selected digitised images of 78 postoperative X-rays by two independent observers and by the same analysis software twice.

The results of the study showed a very high agreement between the readings of the two methods (the largest difference was 0.6 degrees) and two observers (the largest difference being 0.08 degrees) indicating excellent intra and inter observer reliability. The lowest correlation was 0.82 and this was between software reading 1 of observer 1 and software reading 1 of observer 2. The highest correlation of 0.99 was between software reading 1 and software reading 2 for the same observer. The software analysed the x-rays with precision and accuracy and was much faster than manual measurement. A further benefit of the computerised method is an unskilled operator can be trained in 15 minutes to use the software

The aim of this study was to correlate two outcome measurements of clubfoot surgery. A modified, partially subjective, clinical scoring system was compared with an objective biomechanical assessment, using the optical Dynamic Pedobarograph foot pressure system. The outcomes of the latter method were developed into a classification system for future prospective studies and to complement clinical evaluation of patients, especially those with relapse.

Many different functional outcome measures have been designed. Differing number of points are allocated to various subjective and objective items of relevance. The weighting given to each item in the overall score depends entirely on the importance the surgeon believes that particular item has on what he believes constitutes a good corrected clubfoot. This makes the scoring systems arbitrary and therefore results of clubfoot surgery between various centres impossible to compare. Sixteen patients [21 feet] were randomly selected from a poll of patients that had undergone clubfoot surgery. The operations were carried out by a single surgeon and consisted of a lateral-posteromedial peritalar release utilising the Cincinnati incision. Post-operatively, all feet were independently classified using a modified scoring system, based on the ones designed by Laaveg and Ponseti and the one by McKay, which scores both objective and subjective findings. This system has a good interobserver reproducibility. After finalisation of treatment, patients were referred to the Foot Pressure Analysis Clinic in Dundee where a novel method has been developed for the evaluation of clubfeet, using a static and dynamic foot pressure analysis system which provides both a graphical and analytical model for comparison. A pedobarographic classification system was developed. An excellent result entails that the patient does not require further treatment. A good result has been achieved if a near normal posture and pressure distribution is recorded. However, this means that there are still functional problems, which, as the foot matures, may lead to future relapse. These feet may therefore require long-term treatment with an orthotic support to let the foot develop its normal shape. A fair result requires major orthotic support of shoe adaptation, or further surgical releases. The correlation between clinical and biomechanical outcomes in the 21 feet was calculated using Kendall’s tau rank test for non-parametric data. The r value was 0.3524, which was significant [p< 0.05]

There is a significant correlation between the above mentioned outcome measurements. Biomechanical assessment cannot replace clinical evaluation, but can complement it and perhaps give a more subtle and earlier prediction of the need for further additional treatment. This technique has not only proven to be objective but also clinically valuable and cost effective. A prospective study to refine this biomechanical classification system into a reliable predictor of relapse in surgically corrected clubfeet is currently being considered.