Medial Loading Research Articles

Identification and correlation of human footfall load parameters using multivariate analysis.

This research had two main objectives: to identify and quantify the multiple reaction parameters of human footfall load histories for 24 subjects; and to seek statistical correlations of the reaction parameters with two gaits: fitness walking and running, with two footfall surfaces: rigid and mat, and with two subject attributes: gender and arch index. These reaction parameters, measured with a force plate, include the subjects' foot reaction forces in the three orthogonal directions and the particular features of these forces such as their duration, average values, peak values, and rates of loading. An automated data retrieval-software system evaluated these reaction parameters. The statistical correlations were made using principal component analysis (PCA), a method that projected the 13 identified footfall reaction parameters onto subsets of three or four parameters called principal components that contained most of the variance of the original thirteen. The results, among others, show couplings between the vertical and the peak medial load, but an uncoupling of the posterior-anterior loads with the loads in the other two directions.

Dynamic plantar pressure distribution measurements in hemiparetic patients

Objective. A comparison of plantar pressure distribution of hemiparetic patients with a control group was performed to determine quantitative, objective and reproducible criteria for better assessment of hemiparetic gait. Design. This empirical, descriptive study used a clinical sample of 18 hemiparetic patients and compared the data to previously published data from 111 healthy persons. Background. Several biomechanical methods have been used in the past to evaluate and classify hemiplegic gait, for example kinetic, cinematographic, or electromyographic systems, but plantar pressure distribution measurement has not been studied. Methods. Peak pressures were determined under the feet of 18 hemiparetic patients during stance phase using a capacitive pressure distribution platform (EMED-F01 system, Novel GmbH). Results. Hemiparetic patients showed considerably lower peak pressures under all anatomical structures and an unexpected medial load shift in the forefoot. Conclusions. The grade of spasticity seems to be the most important cause for expression of the medial load shift. Individual pressure distribution gait analysis, as shown in an example, may improve assessment and therapy of hemiparetic patients.

Pressure distribution under the foot at the take off in volleyball jumps and fosbury flop high jumps

s-International Society of Biomechanics XIV Congress 1993 677 PRESSURE DISTRIBUTION UNDER THE FOOT AT THE TAKE OFF IN VOLLEYBALL JUMPS AND FOSBURY FLOP HIGH JUMPS Thomas L. Milani and Ewald M. Hennig Biomechanik Labor, Universitat GHS Essen, Germany For injury prevention and to optimize the perfomlance of athletes, the knowledge of local pressures under the foot may reveal important informations for medical doctors, therapists, and coaches.Using in-shoe pressure dishibution measurements, the present study was performed to investigate the loads beneath the foot in high jumps and during the take off phase to volleyball jumps. Founy healthy track and field athletes volunteered to participate in this study. They performed 5 repetitive trials of fosbury flop and volleyball jumps in one experimental session, using the same shoe. Ten piezoceramic sensors were taped onto the plantar surface of the foot at defined anatomical landmarks. All measurements were performed with a portable, battery operated unit at a rate of 750 Hz per channel. Data collection was triggered by remote control using a radio-controlled signal. Based on five jumping trials the mean peak pressures, impulses, relative loads and contact times under the foot were determined. The general pattern shows a high lateral loading of the foot during fosbury flop high jumps and a strong medial load for the volleyball take off. The highest peak pressure values were found for the fosbury flop under the medial and lateral heel. In the rearfoot, increased peak pressures and relative loads are apparent for the medial heel region in both conditions. This is probably due to a strong pronation at the initial contact of the foot in both movements. The extreme eversion of the foot during the fosbury flop results in an excessive pronation, thus producing high mediolateral pressure differences in the heel. Accentuated peak pressures were found under the heel and the first ray of the foot during the take off in VOlleyball jumps. This is also visible in the relative load pattern. The first ray of the foot has to bear 45.9 % of the total Ioad.This large contribution demonstrates the importance of the fust ray in lifting the body for predominantly vertical jumps. PLAYER CONTRIBUTIONS IN A RUGBY UNION SCRUM Peter D. Milbum Department of Biomedical Science University of Wollongong, Wollongong NSW 2500, Australia Despite its importance to the game and the fact the strum is the collective effort of eight players each having a distinctive role, very little information is available on the contributions of individual players. Each unit of the scmm (front-row only, front-row plus second-row, full strum minus flankers, and full strum minus lock) were measured for force generated by pushing against an instrumented strum machine. A subtractive model was used to determine the contribution of each sub-unit. The large forces exerted at engagement sometimes exceeded the reported structural limits of the cervical spine and represented a potential for serious injury. The contribution of strum units were front-row (37%), second-row (42%), flankers (9%) and number eight (12%). Vertical and lateral shear forces changed little with the addition of more players. The combined maximum forward force for each player was 17725 N which represented three times that recorded for the full strum (5760 N). This reflects the extent to which player’s efforts were attenuated by the elastic and compressive tissues in the body as well as some of the forward force being “lost” to less efficient lateral and vertically directed components of force. WEIGHT TRANSFER IN BASKETBALL SHOOTING S.A. Miller and R.M. Bartlett Sport and Exercise Science Research and Development Unit, Crewe+Alsager Faculty, Manchester Metropolitan University, Alsager ST7 2HL, UK. Three-dimensional cinematographic techniques were used to determine the pattern of weight transfer for right-handed subjects at three shooting distances (2.74 m, 4.57 m, 6.40 m). Both antero-posterior and medio-lateral support base dimensions were similar at all distances. A posterior-anterior transfer was found for all shooting distances, an increasing amount of which occurred between take-off and ball release as shooting distance increased. Weight transfer from right to left was also in evidence, with the final position being increasingly closer to the leftmost edge of the base of support. Thus, short range shots were character&d by weight transfer from right posterior to mid support base, and medium and long range shots by transfer from mid-Iear to left-anterior support base. As at&o-posterior movement is required as an aid to ball release speed, it is recommended that medio-lateral movement at release is eliminated by moving the ball to the mid-sagittal plane of the body as early as possible during the shooting process.

Variation of medial and lateral plateau loads at the knee joint with different lever arms of the ground reaction force vector

Variation of medial and lateral plateau loads at the knee joint with different lever arms of the ground reaction force vector

Functional Comparison of Posterior Cruciate Retained versus Cruciate-Sacrificed Total Knee Arthroplasty

Gait of 11 patients with bilateral paired posterior cruciate-retaining and cruciate-sacrificing total knee arthroplasties (TKA) was studied preoperatively and two years postoperatively on walking and stair climbing. Five-year clinical and roentgenographic examinations were included in the study. Differences between the two prostheses were noted both in level walking and in stair climbing. On level walking, cruciate-sacrificed TKA had more flexion in loading response and increased flexion and varus moments with increased muscle activity of quadriceps and biceps femoris. Abnormal gaits common to both types of knee were decreased flexion in stance and decreased single-limb stance. Both knees had a stiff-legged gait during stance. On stairs, the cruciate-sacrificed TKA substituted soleus muscle activity for knee stability. The single-limb stance and range of motion were similar for both knees. In clinical terms, the cruciate-sacrificed TKA is less efficient and has greater medial loading and higher joint reaction forces that may affect durability of the prosthesis. The five-year knee scores, patient satisfaction, and roentgenographic examinations were equal for both sets of knees.

Biomechanical Evaluation of Anatomic Reduction Versus Medial Displacement Osteotomy in Unstable Intertrochanteric Fractures

The biomechanical characteristics of anatomic reduction versus medial displacement osteotomy were compared for four-part intertrochanteric fractures experimentally produced in cadaver femurs. Eighteen pairs of femurs were assigned randomly to either the anatomic (A) or the medial displacement (MD) group and instrumented with multiple strain gauges. The femurs in the MD group were tested while intact and following four-part fracture with fixation. The femurs in the A group were first tested intact, followed by a stable two-part fracture with fixation, and then by a four-part fracture with fixation and perfect reduction of the posteromedial fragment (PMF) with a lag screw, partial reduction of the PMF, and with the PMF omitted. All fractures were fixed with a 135 degrees, four-hole, sliding hip screw. The strain distribution in the MD group changed significantly after fracture. The plate tensile strain increased by 360% while the compressive calcar strain decreased 85%. The plate tensile strain in the A group also increased significantly after four-part fracture when the PMF was perfectly reduced (160%), partially reduced (290%), or discarded (275%); the calcar compressive strains for these subgroups decreased approximately 50%. This laboratory study indicates that anatomic reduction of four-part intertrochanteric fractures with the sliding hip screw, regardless of the presence or position of the PMF, provides significantly higher compression across the calcar region and significantly lower tensile strain on the plate than fractures reduced by medial displacement osteotomy. The more physiologic strain distribution and the increased medial load transmission support the use of anatomic reduction for the treatment of unstable intertrochanteric fractures.

Biomechanical study of the pitching elbow.

Medial-tension injuries of the pitching elbow are well recognized. One contributing factor is the extreme valgus which has been noted to occur during the acceleration phase of throwing. It is hypothesized that breaking pitches generate higher medial loading because of the pronation and supination required to impart spin to the ball. The pitching motion is a complex action of all body segments to produce maximum linear and angular acceleration of the ball. The purpose of this study was to correlate elbow loading with pitching style. We measured the forearm segment for axial and tangential (varus-valgus plane) acceleration using accelerometers attached to the forearm and hand. Muscle activity was measured by EMG. Forearm rotation was assessed by stroboscopic photography. Despite different delivery styles when throwing breaking pitches, each pitcher demonstrated patterns of muscle activity and acceleration which were similar. Deceleration forces were lower than acceleration forces. Pronation and supination were documented and contribute to the direction of ball spin. Accelerometers can be used to evaluate pitching mechanics. We suggest that the main factors causing an elbow injury are the amount of throwing and the force with which the ball is thrown.

The Pemmican B.M.J

<h3>Objective.</h3> Few if any prevention strategies are available for knee osteoarthritis (OA). In those with symptomatic medial OA, the contralateral knee may be at high risk of disease, and a reduction in medial loading in that knee might prevent disease or its progression there. Our aim was to determine how often persons with medial OA on 1 side had either concurrent or later medial OA on the contralateral side, and whether an intervention known to reduce medial loading in affected knees with medial OA might reduce medial loading in the contralateral knee. Lateral wedge insoles reduce loading across an affected medial knee but their effect on the contralateral knee is unknown. <h3>Methods.</h3> To determine the proportion of persons with medial knee OA who had concurrent medial contralateral OA or developed contralateral medial OA later, we examined knee radiographs from the longitudinal Framingham Osteoarthritis Study. Then, to examine an approach to reducing medial load in the contralateral knee, 51 people from a separate study with painful medial tibiofemoral OA underwent gait analysis wearing bilateral controlled shoes with no insoles, and then with 2 types of wedge insoles laterally posted by 5°. Primary outcome was the external knee adduction moment (EKAM) in the contralateral knee. Nonparametric CI were constructed around the median differences in percentage change in the affected and contralateral sides. <h3>Results.</h3> Of Framingham subjects with medial radiograph knee OA, 137/152 (90%) either had concurrent contralateral medial OA or developed it within 10 years. Of those with medial symptomatic knee OA, 43/67 (64%) had or developed the same disease state in the contralateral knee. Compared to a control shoe, medial loading was reduced substantially on both the affected (median percentage EKAM change −4.84%; 95% CI −11.33% to −0.65%) and contralateral sides (median percentage EKAM change −9.34%; 95% CI −10.57% to −6.45%). <h3>Conclusion.</h3> In persons with medial OA, the contralateral knee is also at high risk of medial OA. Bilateral reduction in medial loading in knees by use of strategies such as lateral wedge insoles might not only reduce medial load in affected knees but prevent knee OA or its progression on the contralateral side.