Ceri Diss

The biomechanics of one-footed vertical jump performance in unilateral trans-tibial amputees.

This study investigated vertical jumps from single support for two trans-tibial amputees from a standing position. The mechanisms used to achieve flight and the compensatory mechanisms used in the production of force in the absence of plantarflexors are detailed. Two participants completed countermovement maximum vertical jumps from the prosthetic and the sound limbs. The jumps were recorded by a 7-camera 512 VICON motion analysis system integrated with a Kistler forceplate. Flight height was 5 cm jumping from the prosthetic side and 18–19 cm from the sound side. The countermovement was shallower and its duration was less on the prosthetic side compared to the sound side. The reduced and passive range of motion at the prosthesis resulted in an asymmetrical countermovement for both participants with the knee and ankle joints most affected. The duration of the push-off phase was not consistently affected. At take-off the joints on the sound side reached close to full extension while on the prosthetic side they remained more flexed. Joint extension velocity in the push-off phase was similar for both participants on the sound side, though the timing for participant 2 illustrated earlier peaks. The pattern of joint extension velocity was not a smooth proximal to distal sequence on the prosthetic side. The magnitude and timing of the inter-segment extensor moments were asymmetrical for both subjects. The power pattern was asymmetrical in both the countermovement and push-off phases; the lack of power generation at the ankle affected that produced at the remaining joints.

Examining Hardiness, Coping and Stress-Related Growth Following Sport Injury

This study aimed to explain how injured athletes high in hardiness experienced stress-related growth and why athletes low in hardiness are less likely to derive such benefits. Twenty participants were theoretically sampled into high (n = 10) and low (n = 10) hardiness groups. Semistructured interviews were used for data collection. Findings revealed that athletes high in hardiness experienced stress-related growth from having an emotional outlet, which enabled them to reframe their injury and experience positive affect. In contrast, athletes low in hardiness had no emotional outlet, which led to suboptimal outcomes. These findings have important implications for practitioners working with injured athletes.

Mechanisms to absorb load in amputee running

Background: We aimed to determine if a shock absorbing pylon (SAP) influenced the ground reaction force characteristics and the shock absorbing mechanisms compared to a rigid pylon (Rigid) during the loading phase in running. Objectives: To determine if the SAP influences the mechanisms of loading compared to the Rigid condition. Study Design: A convenience sample of transtibial amputees participated in a laboratory-based study. The prosthetic set-up was randomly altered fd\sdsd. Methods: Five recreationally active male transtibial amputees age: 18–50 years; mean mass: 86.7 ± 17.5 kg; height: 1.77 ± 0.07 m) volunteered from a population-based sample. They completed a within-participant-designed study assessing a SAP and a Rigid condition during running. Kinematic and kinetic data were collected during two sessions following a one-week customization period. Results: Loading rate, peak vertical and horizontal ground reaction forces and the time to each measure along with knee and hip angular displacement, absorbing powers and work done between the SAP and Rigid conditions were not systematically affected by the prosthetic condition. Conclusions: The effect of the SAP was minimal and inconsistent in the loading phase, with only some amputees presenting higher and others with lower values for the tested variables. Clinical relevance The inclusion of a prosthetic shock absorber in the form of a SAP did not systematically alter the kinetic characteristics or shock absorbing mechanisms of the residual joints. It appears that the prescription of a SAP is not justified for these recreationally active amputees.

Patellar tracking during the gait cycle

Purpose. To assess normal patellar tracking during walking using the 9-camera infrared system. Methods. Four men and 6 women aged 25 to 33 (mean, 29) years each performed 16 walking trials on one occasion. They had prominent patellae with minimal soft tissues (minimising skin artefacts), and their knees and lower limbs were normal and symmetrical. 12 retro-reflective markers (2.5 cm in diameter) were taped to anatomic landmarks of the lower body. Two additional markers (1.4 cm in diameter) were first placed on the medial and lateral points and then proximal and distal points of the patella. Patellar motion relative to the centre of the knee joint was defined as angles between the centre of the knee joint and the 2 sets of patellar markers (medial-lateral and proximal-distal). The mean, maximum, and minimum values of these angles in a standing position were recorded, as was patellar tracking during walking. The X, Y, and Z coordinates for each marker were smoothed out throughout the capturing time. A single gait cycle per trial was chosen for analysis. Results. During walking, the centre of the knee joint and the patella did not move in unison, and the extent of separation was subject dependent. In 70% of the participants, the maximum angle between the centre of the knee joint and each set of markers occurred in the swing phase (0–43%) of the gait cycle. When analysing both sets of markers together, the percentage of participants became 60%. The extent of knee flexion was subject dependent. There was more medial-lateral motion (shift) of the patella than proximal-distal (tilt) motion during the gait cycle. These indicated that the maximum amount of patellar shift and tilt occurred in the swing and early stance phases of the gait cycle and that abnormal patellar motion can be detected if excessive shift or tilt occurs outside of these phases. Conclusion. Patella mal-tracking could be attributed to the position of the lower body segments rather than the absorption or generation of forces.

Asymmetrical loading demands associated with vertical jump landings in people with unilateral transtibial amputation

Loading symmetry during vertical jump landings between a person with amputations intact and prosthetic limbs was assessed to determine the role of each limb in controlling the downward momentum of the center of mass during landing. Six participants with unilateral transtibial amputation (TTA) and ten nondisabled participants completed 10 maximal vertical jumps, of which the highest jump was analyzed. Contralateral symmetry was assessed through the Symmetry Index (SI), while symmetry at the group level was assessed through a Mann-Whitney U test. Participants with TTA performed quasi-unilateral landings onto the intact limbs, resulting from either the incapability of the prosthetic ankle to plantar flex or increased residual-limb knee and hip flexion. In the loading phase, the participants with TTA displayed reduced prosthetic-side peak vertical forces (p = 0.04) along with reduced prosthetic-side ankle range of motion (p < 0.001), extensor moments (p = 0.03), and negative work generated (p = 0.00). Individual asymmetries were evident in the peak vertical force magnitudes (SI = 51%-140%), duration from touchdown to peak vertical force (SI = 52%-157%), ankle joint angles at touchdown (SI = 100%-538%), ranges of motion (SI = 147%-200%), knee (SI = 66%-179%) and hip (SI = 87%-132%) extensor moments, and work done at the ankle (SI = 155%-199%) and hip (SI = 83%-204%). High peak forces (25.25 +/- 4.89 N·kg(-1) intact limb and 14.61 +/- 8.28 N·kg(-1) prosthetic limb) from significantly lower (p < 0.001) landing heights than the nondisabled participants indicate a potential injury risk associated with landing for people with TTA.

Examining the effects of combined gait retraining and video self-modeling on habitual runners experiencing knee pain: A pilot study

This multidisciplinary study aimed to reduce stride length (SL) by 2%‐4% for two runners (P1 and P2) experiencing chronic knee pain using a biomechanical gait retraining and video self‐modeling intervention. The pre‐ and post‐test design examined the acute changes in biomechanical and psychological factors following a 4‐week intervention, which involved four gait retraining sessions and four gait consolidation sessions. Participants watched self‐modeling videos twice daily in between sessions. P1 met the required SL reduction (2.61%), resulting in a 9% decrease in peak vertical ground reaction force combined with a 72% reduction in peak knee abduction moment. P1 demonstrated large positive effects for four performance‐ and two injury‐based psychological variables (ES = 0.85‐4.30) and a large negative effect for one injury‐based psychological variable (ES = 1.50). P2 did not meet the required reduction in SL (1.3%); the response was an increase in vertical ground reaction forces (0.90%). P2 demonstrated large positive effects for three performance‐ and two injury‐based psychological variables (ES = 3.00‐4.28) and a large negative for one performance‐based psychological variable (ES = 3.65). The consideration for individualized responses to interventions targeting a change in gait is warranted, as applying a “one‐size‐fits‐all” approach may be detrimental to reducing injury pain.