Vector-field statistics for the analysis of time varying clinical gait data.

BACKGROUND: In clinical settings, the time varying analysis of gait data relies heavily on the experience of the individual(s) assessing these biological signals. Though three dimensional kinematics are recognised as time varying waveforms (1D), exploratory statistical analysis of these data are commonly carried out with multiple discrete or 0D dependent variables. In the absence of an a priori 0D hypothesis, clinicians are at risk of making type I and II errors in their analyis of time varying gait signatures in the event statistics are used in concert with prefered subjective clinical assesment methods. The aim of this communication was to determine if vector field waveform statistics were capable of providing quantitative corroboration to practically significant differences in time varying gait signatures as determined by two clinically trained gait experts. METHODS: The case study was a left hemiplegic Cerebral Palsy (GMFCS I) gait patient following a botulinum toxin (BoNT-A) injection to their left gastrocnemius muscle. FINDINGS: When comparing subjective clinical gait assessments between two testers, they were in agreement with each other for 61% of the joint degrees of freedom and phases of motion analysed. For tester 1 and tester 2, they were in agreement with the vector-field analysis for 78% and 53% of the kinematic variables analysed. When the subjective analyses of tester 1 and tester 2 were pooled together and then compared to the vector-field analysis, they were in agreement for 83% of the time varying kinematic variables analysed. INTERPRETATION: These outcomes demonstrate that in principle, vector-field statistics corroborates with what a team of clinical gait experts would classify as practically meaningful pre- versus post time varying kinematic differences. The potential for vector-field statistics to be used as a useful clinical tool for the objective analysis of time varying clinical gait data is established. Future research is recommended to assess the usefulness of vector-field analyses during the clinical decision making process

Suction technique to improve cement penetration under the tibial component in total knee arthroplasty

Improving the longevity and reliability of cemented total knee arthroplasty remains an important part of orthopaedic research. This paper examines the recently described method of preparation of the cancellous surface of the tibia using suction cannulae in the proximal tibia and stem recess during pulsatile lavage and component fixation. The technique provides a surface clear of debris, fat, blood and marrow, and prevents backflow of blood. A retrospective analysis of post-operative radiographs shows significant improvement in the penetration of cement into the tibial plateau, and improved cement profile towards the periphery. Techniques of stem cementation are also compared, and it is recommended that for this particular design implant, cement should be applied into the cut stem recess in the tibia rather than to the stem of the implant itself. This technique of preparation of the cut surface of the tibia is a simple and, to-date, complication-free method of reliably providing satisfactory cement penetration during total knee arthroplasty

Muscle Histopathology in Children with Spastic Cerebral Palsy Receiving Botulinum toxin Type A

Introduction: Botulinum toxin A (BoNTA) is routine treatment for hypertonicity in children with cerebral palsy (CP). Method: Single blind prospective cross sectional study of 10 participants (mean age 11 years,7 months) was done to determine the relationship between muscle histopathology and BoNTA in treated medial gastrocnemius muscle of children with CP. Open muscle biopsies were taken from medial gastrocnemius muscle and vastus lateralis (control) during orthopedic surgery. Results: Neurogenic atrophy in the medial gastrocnemius was seen in 6 participants between 4 months to 3 years post BoNTA. Type 1 fiber loss with type 2 fiber predominance was significantly related to the number of BoNTA injections (r = 0.89, P < 0.001). Discussion: The impact of these changes in muscle morphology on muscle function in CP is not clear. It is important to consider rotating muscle selection or injection sites within the muscle or allowing longer time between injections

Ultrasound characterization of medial gastrocnemius tissue composition in children with spastic cerebral palsy

Introduction: In this study we aimed to characterize muscle composition of the medial gastrocnemius in children with spastic cerebral palsy (SCP) using quantitative ultrasound. Methods: Forty children with SCP, aged 4–14 years, participated in this study. Children were grouped according to the gross motor function classification system (GMFCS I–V) and compared with a cohort of age- and gender-matched, typically developing children (TD; n = 12). Ultrasound scans were taken of the medial gastrocnemius. Images were then characterized using grayscale statistics to determine mean echo intensity (EI) and the size and number of spatially connected homogeneous regions (i.e., blobs). Results: Significant differences in skeletal muscle composition were found between children with SCP and their TD peers. Children classified as GMFCS III consistently exhibited the highest EI and blob area. Conclusions: This study demonstrates altered tissue composition in children with SCP visualized using ultrasound. Further work is required to determine the pathophysiology contributing to these alterations in SCP

Children with cerebral palsy have larger Achilles tendon moment arms than typically developing children

The effectiveness of the plantarflexor muscle group to generate desired plantarflexion moments is modulated by the geometry of the Achilles tendon moment arm (ATMA). Children with cerebral palsy (CP) frequently have reduced plantarflexion function, which is commonly attributed to impaired muscle structure and function, however little attention has been paid to the potential contribution of ATMA geometry. The use of musculoskeletal modelling for the simulation of gait and understanding of gait mechanics, rely on accuracy of ATMA estimates. This study aimed to compare 3D in-vivo estimates of ATMA of adults, children with CP and typically developing (TD) children, as well as compare 3D in-vivo estimates to linearly scaled musculoskeletal model estimates. MRI scans for eight children with CP, 11 TD children and nine healthy adults were used to estimate in-vivo 3D ATMA using a validated method. A lower limb musculoskeletal model was linearly scaled to individual tibia length to provide a scaled ATMA estimate. Normalised in-vivo 3D ATMA for children with CP was 17.2% ± 2.0 tibia length, which was significantly larger than for TD children (15.2% ± 1.2, p = 0.013) and adults (12.5% ± 0.8, p &lt; 0.001). Scaled ATMA estimates from musculoskeletal models significantly underestimated in-vivo estimates for all groups, by up to 34.7%. The results of this study show children with CP have larger normalised 3D ATMA compared to their TD counterparts, which may have implications in understanding reduced plantarflexor function and the efficacy of surgical interventions whose aim is to modify the musculoskeletal geometry of this muscle group

Neuromuscular electrical stimulation-assisted gait increases muscle strength and volume in children with unilateral spastic cerebral palsy

© 2015 Mac Keith Press. Aim: To determine if neuromuscular electrical stimulation (NMES) applied to the ankle dorsiflexors during gait improves muscle volume and strength in children with unilateral spastic cerebral palsy (CP). Method: Thirty-two children (15 females, 17 males; mean age 10y 8mo, age range 5y 5mo-18y 1mo) with unilateral spastic CP and a Gross Motor Function Classification System of level I or level II were randomly assigned to either the 8-week daily NMES treatment group or control group (usual or conventional treatments). Outcomes at week 8 (post-NMES) and week 14 (carryover) included magnetic resonance imaging for muscle volumes (tibialis anterior, anterior compartment, and gastrocnemius), strength (hand-held dynamometry for isometric dorsiflexion strength and heel raises for functional strength), and clinical measures for lower limb selective motor control. Results: At week 8, the treatment group demonstrated significantly (p&lt;0.05) increased muscle volumes for tibialis anterior, anterior compartment, medial and lateral gastrocnemius, and dorsiflexion strength not only when compared to their baseline values but also when compared to the control group at week 8. At week 14, both tibialis anterior and lateral gastrocnemius volumes in the treatment group remained significantly increased when compared to their baseline values. However, only lateral gastrocnemius volumes had significantly greater values when compared to the control group at week 14. There were no between group differences in the clinical measures for lower limb selective motor control at week 8 and 14. Interpretation: Eight weeks of daily NMES-assisted gait increases muscle volume and strength of the stimulated ankle dorsiflexors in children with unilateral spastic CP. These changes are use-dependent and do not carry over after the 8-week treatment period. Gastrocnemius volume also increased post-treatment with carryover at week 14

Radiolucent lines below the tibial component of a total knee replacement (TKR) – a comparison between single-and two-stage cementation techniques

Early non-progressive horizontal radiolucent lines (RLLs) (<2 mm) under the tibial component following cemented total knee replacement (TKR) are considered to result from poor cement injection into cancellous bone. These RLLs may facilitate the entry of joint fluid and wear debris into the interface, which may proceed to ballooning osteolysis. There is currently no consensus on the preferred cementing technique (single- versus two-stage cementation) in TKR. We have prospectively analysed postoperative radiographs in 50 consecutive TKRs to compare the RLLs following single- (25 TKRs) and two-stage (25 TKRs) cementation techniques. Of the TKR radiographs studied, 26 (52%) had RLLs; nine (36%) of these were single-stage TKRs, and 17 (68%) were two-stage TKRs. This study demonstrates that single-stage cementing may be superior to the two-stage technique in terms of avoiding RLLs in immediate postoperative TKRs