Athletic groin pain (part 2): a prospective cohort study on the biomechanical evaluation of change of direction identifies three clusters of movement patterns.

BACKGROUND: Athletic groin pain (AGP) is prevalent in sports involving repeated accelerations, decelerations, kicking and change-of-direction movements. Clinical and radiological examinations lack the ability to assess pathomechanics of AGP, but three-dimensional biomechanical movement analysis may be an important innovation. AIM: The primary aim was to describe and analyse movements used by patients with AGP during a maximum effort change-of-direction task. The secondary aim was to determine if specific anatomical diagnoses were related to a distinct movement strategy. METHODS: 322 athletes with a current symptom of chronic AGP participated. Structured and standardised clinical assessments and radiological examinations were performed on all participants. Additionally, each participant performed multiple repetitions of a planned maximum effort change-of-direction task during which whole body kinematics were recorded. Kinematic and kinetic data were examined using continuous waveform analysis techniques in combination with a subgroup design that used gap statistic and hierarchical clustering. RESULTS: Three subgroups (clusters) were identified. Kinematic and kinetic measures of the clusters differed strongly in patterns observed in thorax, pelvis, hip, knee and ankle. Cluster 1 (40%) was characterised by increased ankle eversion, external rotation and knee internal rotation and greater knee work. Cluster 2 (15%) was characterised by increased hip flexion, pelvis contralateral drop, thorax tilt and increased hip work. Cluster 3 (45%) was characterised by high ankle dorsiflexion, thorax contralateral drop, ankle work and prolonged ground contact time. No correlation was observed between movement clusters and clinically palpated location of the participant's pain. CONCLUSIONS: We identified three distinct movement strategies among athletes with long-standing groin pain during a maximum effort change-of-direction task These movement strategies were not related to clinical assessment findings but highlighted targets for rehabilitation in response to possible propagative mechanisms. TRIAL REGISTRATION NUMBER: NCT02437942, pre results.

The effect of stopping before turning on the direct observational measure of whole body turning bias.

Turning bias, the preferential tendency to turn toward a given direction has been reported in both rodents and human participants. The observational gait method of determining turning bias in humans requires a stop prior to turning. This study removed the stop and hypothesised that turning bias would remain the same between stop and non-stop conditions if bias was solely under the control of neurochemical asymmetries. The results showed that statistically turning bias remained the same (to the left) regardless of method used but there was no agreement between the methods thus rejecting the hypothesis. It is likely that when not stopping biomechanical factors related to gait when turning influence the direction of turn rather than solely neurochemical asymmetries.

The effect of different unstable footwear constructions on centre of pressure motion during standing.

BACKGROUND: The aim of this study was to test the effect different unstable footwear constructions have on centre of pressure motion when standing. METHODS: Sixteen young female volunteers were tested in five conditions, three unstable footwear (Reebok Easy-Tone, FitFlop and Skechers Shape-Ups), a standard shoe and barefoot in a randomised order. Double and single leg balance on a force plate was assessed via centre of pressure excursions and displacements in each condition. RESULTS: For double leg and single leg standing centre of pressure excursions in the anterior-posterior direction were significantly increased wearing Skechers Shape-Ups compared to barefoot and the standard shoe. For the Reebok Easy Tone during single leg standing excursions in the anterior-posterior direction were significantly greater compared to the barefoot condition. Cumulative displacement of the centre of pressure in medial-lateral direction increased significantly during single leg standing when wearing Skechers Shape-Ups compared to barefoot and standard shoe as well as for Reebok Easy Tone vs. barefoot. DISCUSSION: It would appear from these quiet standing results that the manner of the construction of instability shoes effects the CoP movement which is associated with induced instability. Greater CoP excursion occurred in the A-P direction while the cumulative displacements were greater in the M-L direction for those shoes with the rounded sole and soft foam and those with airpods. The shoe construction with altered density foam did not induce any change in the CoP movement, during quite standing, which tends to suggest that it is not effective at inducing balance. Not all instability shoes are effective in altering the overall instability of the wearer.

Turning bias and lateral dominance in a sample of able-bodied and amputee participants.

Turning bias is the tendency to turn towards a given direction. Conflicting results from previous studies suggest that a number of factors may influence turning direction. The aim of this study was to determine if biomechanical asymmetries influence turning bias. A total of 100 able-bodied participants, and 30 trans-tibial amputees who, by definition, possess a functional asymmetry, volunteered to participate in the study. The right hand and right foot were significantly dominant for the able-bodied sample. Able-bodied participants showed a significant turning preference towards the left, which was opposite to the dominant hand and foot. The amputees were significantly right-hand dominant and the side of the amputation influenced foot dominance. The amputee sample showed no preferred turning direction. Turning bias indices in the amputee sample were not significantly associated with handedness, footedness, side of amputation, or dominance prior to amputation. The lack of a preferred direction of turn in the amputee sample suggests that biomechanical asymmetries can influence turning bias.

Strategies used for unconstrained direction change during walking.

Full functional mobility requires adaptations, such as turning, to the basic straight locomotor pattern. The aim was to assess the mechanics of completing a complex turning manoeuvre. A full 3-dimensional kinematic and kinetic analysis of the ipsilateral limb was carried out during both straight gait and unconstrained turning through 90 degrees. 10 healthy university students participated. Analysis indicated that two distinctive substrategies of the spin turn-ipsilateral pivot and ipsilateral crossover-were employed. The ipsilateral pivot was the more dynamic turn and required two additional power phases at the ankle and hip to facilitate the pivot phase. The ipsilateral crossover uses a fall into the new direction. The spin turn is a more complex action than previously indicated.

A three-dimensional biomechanical comparison between turning strategies during the stance phase of walking.

Two main strategies for turning exist, the step and spin turns. A three-dimensional analytical comparison between these strategies has not been reported in the literature. Establishing differences between the two strategies is important if providing gait-training advice to clinical populations. The study is the first to compare 90 degrees spin and step turns on the basis of three-dimensional kinematic and kinetic analysis. The turns were free of constraints, thus participants knew when to turn resulting in feed-forward control. Two separate and distinct spin turn sub-strategies were used, the 'ipsilateral crossover' and 'ipsilateral pivot'. These turns required increased range of motion (RoM) in the transverse plane and greater muscular demand than the step turn. The step turn provided a number of advantages over the spin turns, such as keeping a wide base of support, it did not require increased co-ordination, RoM out of the sagittal plane and moments were generally less than the spin turns and no more demanding than straight gait. Further work involving many more participants is required to validate these initial findings.

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.

The effect of prosthetic torsional stiffness on the golf swing kinematics of a left and a right-sided trans-tibial amputee.

The golf swing is a biomechanically complex movement requiring three-dimensional movements at the ankle joint complex (AJC), the hips and shoulders. Trans-tibial amputees lose the natural AJC movements as many prostheses do not allow three dimensional foot movements. Torsion devices have been developed and incorporated into prostheses to facilitate internal and external transverse plane rotations. These devices can help amputees to compensate for the loss of movement and to reduce shearing stresses at the stump-socket interface. The primary aim of the present study was to investigate the effects of three torsion devices on body rotations during the golf swing. Two trans-tibial amputees (one right-sided and one left-sided) were analysed using three-dimensional video analysis at address (ADR), the top of the backswing (TBS) and at the end of the follow-through (EFT). The participants played shots with a 3-wood under three different prosthetic conditions (two with a torsion device set to different stiffness values, and one with no torsion device). The results showed that the torsion device served to improve the hip and shoulder rotations of the left-side amputee without increasing perceived stress at the stump. The torsion device had minimal effect on the hip and shoulder rotations of the right-side amputee, although perceived stress was reduced. The difference in results between the right-sided and left-sided amputees was due to the different requirements of each foot during the golf swing. The main problem faced by the right-side amputee was a loss of the sagittal plane movement of ankle joint plantarflexion at EFT, rather than the transverse plane movement.

The design and testing of a composite lower limb prosthesis.

In unilateral lower limb prosthetic gait, the intact limb, together with the hip on the affected side, strive to compensate for the loss of the missing below-knee musculature. The resultant abnormal gait patterns can eventually lead to pathologies of the spine and other joints. The aim of this research was to design a trans-tibial dynamic elastic response (DER) prosthesis which could simulate the power generation and absorption properties of an intact foot and shank segments. A carbon fibre sickle-shaped prosthesis was developed in which the strain energy from the early part of the stride was stored, and was released again at the point of take-off, to simulate the action of the missing musculature. Stress analysis techniques were used in the design of the prosthesis, for the purposes of computing and maximizing the strain energy of the elements. A force transducer was designed into the prosthesis to verify the analysis. Video motion analyses of the prosthesis were carried out in order to determine the most appropriate shape that would reduce gait asymmetries. The research shows that biomechanical techniques, together with good engineering design and the selection of modern materials, can lead to a prosthesis which approaches the function of a natural foot.

Throwing in cricket.

This paper considers the kinematic characteristics of overarm throwing with particular emphasis on the techniques of throwing and pitching in baseball. The technique is subdivided into: (1) sequential pattern of throwing, (2) lead foot contact, (3) preparatory phase, (4) arm acceleration and (5) instant of ball release. Specific biomechanical principles that underpin throwing and their application within baseball are identified. The paper also presents a case study of the three-dimensional characteristics of throwing technique in cricket. The aim was to compare the skill in cricket to that previously researched in baseball. The findings for throwing in cricket are similar to those reported for baseball, indicating that there is a definite crossover in the rationale of how an individual should throw specific to the demands of cricket and baseball. The differences noted--greater elbow flexion at lead foot contact and less external rotation during the preparation phase--can be attributed to the demands placed on the fielder and pitcher specific to their respective sports.

Reducing costs through electronic data interchange.

The times have never been riper for an investment in EDI to pay off for healthcare providers. As suppliers attain their implementation goals for electronic purchase orders, they are expanding their EDI capabilities. One area which seems to be attracting considerable attention is the entire contracting cycle, where there are numerous opportunities for reducing administrative costs and improving accuracy. A detailed example using a buying group's contract cycle shows how EDI can be used at every step of the way, from request for quotation to funds transfer and monthly purchase summaries. EDI can be implemented at any level, from PC to mainframe. Implementation is not cheap and integration may not be easy, but the benefits can justify the cost. The first step to successful implementation is to identify and quantify, throughout the entire organization, reengineering opportunities in which EDI can be used. Two industry organizations, the Health Industry Distributors Association (HIDA) and the Healthcare EDI Corporation (HEDIC) have taken leadership roles in simplifying the implementation process.