Frontal plane movement of the pelvis and thorax during dynamic activities in individuals with and without anterior cruciate ligament injury.

BACKGROUND: For elite athletes with anterior cruciate ligament (ACL) reconstruction, reducing pelvis and trunk obliquities is a common goal of rehabilitation. It is not known if this is also a suitable goal for the general population. This study aimed to quantify pelvis and thorax obliquities during dynamic activities in individuals from the general population with and without history of ACL injury. METHODS: Retrospective analysis of cross-sectional data from 30 participants with ACL reconstruction, 28 participants with ACL deficiency (ACLD), and 32 controls who performed overground walking and jogging, single-leg squat, and single-leg hop for distance. Pelvis and thorax obliquities were quantified in each activity and compared across groups using one-way ANOVA. Coordination was quantified using cross covariance. RESULTS: In the stance phase of walking and jogging, pelvis and thorax obliquities were within ±10° of neutral and there was a negative correlation between the two segments at close to zero phase lag. In single-leg squat and hop, range of obliquities varied across individuals and there was no consistent pattern of coordination. Eight ACLD participants felt unable to perform the single-leg hop. In the remaining participants, range of pelvis (p = 0.04) and thorax (p = 0.02) obliquities was smaller in ACLD than controls. CONCLUSIONS: In challenging single-leg activities, minimal frontal plane motion was not the typical movement pattern observed in the general population. Coordination between the pelvis and thorax was inconsistent within and across individuals. Care should be taken when considering minimising pelvis and thorax obliquities in patients with ACL injury.

Kinematics of knees with osteoarthritis show reduced lateral femoral roll-back and maintain an adducted position. A systematic review of research using medical imaging.

BACKGROUND: While several studies describe kinematics of healthy and osteoarthritic knees using the accurate imaging and computer modelling now possible, no systematic review exists to synthesise these data. METHOD: A systematic review extracted quantitative observational, quasi-experimental and experimental studies from PubMed, Scopus, Medline and Web of Science that examined motion of the bony or articular surfaces of the tibiofemoral joint during any functional activity. Studies using surface markers, animals, and in vitro studies were excluded. RESULTS: 352 studies were screened to include 23 studies. Dynamic kinematics were recorded for gait, step-up, kneeling, squat and lunge and quasi-static squat, knee flexion in side-lying or supine leg-press. Kinematics were described using a diverse range of measures including six degrees of freedom kinematics, contact patterns or the projection of the femoral condylar axis above the tibia. Meta-analysis of data was not possible since no three papers recorded the same activity with the same measures. Visual evaluation of data revealed that knees with osteoarthritis maintained a more adducted position and showed less posterior translation of the lateral femoral condylar axis than healthy knees. Variability in activities and in recording measures produced greater variation in kinematics, than did knee osteoarthritis. CONCLUSION: Differences in kinematics between osteoarthritic and healthy knees were observed, however, these differences were more subtle than expected. The synthesis and progress of this research could be facilitated by a consensus on reference systems for axes and kinematic reporting.

Whole Body Coordination and Knee Movement Control During Five Rehabilitation Exercises.

Knee rehabilitation exercises to improve motor control, target movement fluency, and displacement variability. Although knee movement in the frontal plane during exercise is routinely assessed in clinical practice, optimal knee control remains poorly understood. In this study, 29 healthy participants (height: 1.73 ± 0.11 m, mass: 73.5 ± 16.4 kg, age: 28.0 ± 6.9 years) performed 4 repetitions of 5 rehabilitation exercises while motion data were collected using the VICON PlugInGait full-body marker set. Fluency and displacement variability were calculated for multiple landmarks, including center of mass (CoM) and knee joint centers. Fluency was calculated as the inverse of the average number of times a landmark velocity in the frontal plane crossed zero. Variability was defined as the standard deviation of the frontal plane movement trajectories. CoM fluency and displacement variability were significantly different between tasks (p < .001). CoM displacement variability was consistently smallest compared to the constituent landmarks (p < .005). This was interpreted as a whole body strategy of compensatory variability constraining CoM frontal plane movement. Ipsilateral knee fluency (p < .01) and displacement variability (p < .001) differed substantially between tasks. The role of the weight-bearing knee seemed dependent on task constraints of the overall movement and balance, as well as constraints specific for knee joint stability.

A novel clinical approach for assessing hop landing strategies: a 2D telescopic inverted pendulum (TIP) model.

PURPOSE: Single leg hop for distance is used to inform rehabilitation and return to sport following anterior cruciate ligament reconstruction. However, impairment of landing mechanics may persist after the recommended performance parameter (hop distance) has been met; therefore, alternative methods are required. This study follows the COSMIN guideline to investigate the measurement properties of data from a new instrument (2D TIP). This is a simple motion analysis instrument to assess landing strategy based on more complex biomechanical modelling. METHODS: Data collected in the clinical setting from 30 subjects with chronic ACL deficiency (mean 15.5, SD 4.3 months following injury) before and 6 months after ACL reconstruction and a healthy control group were analysed. Reliability and measurement error were calculated using two repeated measures from three independent raters. Construct validity was assessed by hypothesis testing, and known groups validity and responsiveness were defined by differences between groups. RESULTS: The data demonstrate excellent inter-rater (ICC = 0.81-1.00) and intra-rater (ICC = 0.85-1.00) reliability with low measurement error. Of the eight construct validity hypothesis, six were fully and two partially supported. Between-group differences were significant (P < 0.05) supporting the validity and responsiveness hypothesis. CONCLUSION: 2D TIP is a simple and inexpensive instrument for assessing landing strategy that has demonstrated appropriate reliability, validity and responsiveness in the ACL-injured population. The instrument will now be used to identify altered movement strategies and develop novel rehabilitation interventions that target strategy and performance. LEVEL OF EVIDENCE: Prospective diagnostic study, Level II.

The clinical effectiveness of self-care interventions with an exercise component to manage knee conditions: A systematic review.

OBJECTIVE: Treatment of knee conditions should include approaches to support self-care and exercise based interventions. The most effective way to combine self-care and exercise has however not been determined sufficiently. Therefore the aim was to evaluate the clinical effectiveness of self-care programmes with an exercise component for individuals with any type of knee conditions. METHODS: A keyword search of Medline, CINAHL, Amed, PsycInfo, Web of Science, and Cochrane databases was conducted up until January 2015. Two reviewers independently assessed manuscript eligibility against inclusion/exclusion criteria. Study quality was assessed using the Downs and Black quality assessment tool and the Cochrane Risk of Bias Tool. Data were extracted about self-care and exercise intervention type, control intervention, participants, length of follow-up, outcome measures, and main findings. RESULTS: From the 7392 studies identified through the keyword search the title and abstract of 5498 were screened. The full text manuscripts of 106 studies were retrieved to evaluate their eligibility. Twenty-one manuscripts met the inclusion/exclusion criteria. CONCLUSION: The treatment potential of combined self-care and exercise interventions has not been maximised because of limitations in study design and failure to adequately define intervention content. Potentially the most beneficial self-care treatment components are training self-management skills, information delivery, and goal setting. Exercise treatment components could be strengthened by better attention to dose and progression. Modern technology to streamline delivery and support self-care should be considered. More emphasis is required on using self-care and exercise programmes for chronic condition prevention in addition to chronic condition management.

Assessing participation in the ACL injured population: Selecting a patient reported outcome measure on the basis of measurement properties.

BACKGROUND/AIM: A return to pre injury activity participation remains a common but often elusive goal following ACL injury. Investigations to improve our understanding of participation restrictions are limited by inconsistent use of insufficiently investigated measurement tools. The aim of this study was to follow the consensus based standards for the selection of health measurement instruments (COSMIN) guideline to provide a comparative evaluation of four patient reported outcomes (PROMs) on the basis of measurement properties. This will inform recommendations for measuring participation of ACL injured subjects, particularly in the United Kingdom (UK) National Health Service (NHS). METHODS: Thirteen criteria were compiled from the COSMIN guideline. These included reliability, measurement error, content validity, construct validity, responsiveness and interpretability. Data from 51 subjects collected as part of a longitudinal observational study of recovery over the first year following ACLR was used in the analysis. RESULTS: Of the thirteen criteria, the required standard was met in 11 for Tegner, 11 for International Knee Documentation Committee (IKDC), 6 for Cincinnati Sports Activity Scale (CSAS) and 6 for Marx. The two weaknesses identified for the Tegner are more easily compensated for during interpretation than those in the IKDC; for this reason the Tegner is the recommended PROM. CONCLUSIONS: The Tegner activity rating scale performed consistently well in respect of all measurement properties in this sample, with clear benefits over the other PROMs. The measurement properties presented should be used to inform implementation and interpretation of this outcome measure in clinical practice and research. LEVEL OF EVIDENCE: Level II prospective study.

Motor control strategies during double leg squat following anterior cruciate ligament rupture and reconstruction: an observational study.

BACKGROUND: Anterior cruciate ligament (ACL) injured individuals often show asymmetries between the injured and non-injured leg. A better understanding of the underlying motor control could help to improve rehabilitation. Double leg squat exercises allow for compensation strategies. This study therefore investigated motor control strategies during a double leg squat with the aim to investigate if individuals with ACL rupture (ACLD), ACL reconstruction (ACLR) and healthy control subjects (CONT) used different strategies. METHODS: 20 ACLD and 21 ACLR were compared to 21 CONT subjects. Participants performed eight continuous double leg squats to their maximum depth, while kinematic and kinetic data were collected. Outcome measures were calculated to quantify the behavior of the injured and non-injured legs and the asymmetry between these legs. RESULTS: Squat depth was significantly reduced in ACLR and ACLD compared to CONT (p < 0.05; 106 ± 17°; 105 ± 21°; 113 ± 21°). Peak knee extensor moments (Mkn(mx)) were significantly reduced in ACLR and ACLD compared to CONT in the injured leg only (p < 0.05; 0.045 ± 0.015; 0.046 ± 0.016; 0.059 ± 0.022 body weight.height respectively). There was no significant correlation between symmetry of the support moment (SYM(Msup)) and of the % support moment by the knee (SYM%supkn) in CONT (R(2) = -0.07). Data distribution average indicated good symmetry. ACLR showed a significant correlation between SYM(Msup) and SYM%sup(kn) (R(2) = 0.561) when two participants who did not recover as well were excluded. ACLR controlled knee moment magnitude using two strategies; 1) transfer of support moment to non-injured leg; 2) transfer of support moment from knee to ankle and/or hip of injured leg. These were combined in different proportions, but with the same effect on the knee moment. ACLD showed no significant correlation between SYM(Msup) and SYM%sup(kn) (R(2) = 0.015). Data distribution average indicated reduced symmetry. ACLD therefore used an avoidance strategy: reducing squat depth and subsequently the support moment in the injured leg and the knee contribution. CONCLUSIONS: ACLD and ACLR individuals used different squatting strategies compared to controls, with ACLR using controlled and ACLD using avoidance behavior regarding knee loading. This has major implications for rehabilitation as these kinetic strategies cannot be observed, but result in the injured leg not being exercised as intended.

Activity progression for anterior cruciate ligament injured individuals.

BACKGROUND: Functional exercises are important in the rehabilitation of anterior cruciate ligament deficient and reconstructed individuals but movement compensations and incomplete recovery persist. This study aimed to identify how tasks pose different challenges; and evaluate if different activities challenge patient groups differently compared to controls. METHODS: Motion and force data were collected during distance hop, squatting and gait for 20 anterior cruciate ligament deficient, 21 reconstructed and 21 controls. FINDINGS: Knee range of motion was greatest during squatting, intermediate during hopping and smallest during gait (P < 0.01). Peak internal knee extensor moments were greatest during distance hop (P < 0.01). The mean value of peak knee moments was reduced in squatting and gait (P < 0.01) compared to hop. Peak internal extensor moments were significantly larger during squatting than gait and peak external adductor moments during gait compared to squatting (P < 0.01). Fluency was highest during squatting (P < 0.01). All patients demonstrated good recovery of gait but anterior cruciate ligament deficient adopted a strategy of increased fluency (P < 0.01). During squatting knee range of motion and peak internal knee extensor moment were reduced in all patients (P < 0.01). Both anterior cruciate ligament groups hopped a shorter distance (P < 0.01) and had reduced knee range of motion (P < 0.025). Anterior cruciate ligament reconstructed had reduced fluency (P < 0.01). INTERPRETATION: Distance hop was most challenging; squatting and gait were of similar difficulty but challenged patients in different ways. Despite squatting being an early, less challenging exercise, numerous compensation strategies were identified, indicating that this may be more challenging than gait.

Altered biomechanical strategies and medio-lateral control of the knee represent incomplete recovery of individuals with injury during single leg hop.

Anterior cruciate ligament (ACL) injury can result in failure to return to pre-injury activity levels and future osteoarthritis predisposition. Single leg hop is used in late rehabilitation to evaluate recovery and inform treatment but biomechanical understanding of this activity is insufficient. This study investigated single leg hop for distance aiming to evaluate if ACL patients had recovered: (1) landing strategies and (2) medio-lateral knee control. We hypothesized that patients with reconstructive surgery (ACLR) would have more similar landing strategies and knee control to healthy controls than patients treated conservatively (ACLD). 16 ACLD and 23 ACLR subjects were compared to 20 healthy controls (CONT). Kinematic and ground reaction force data were collected while subjects hopped their maximum distance. The main output parameters were hop distance, peak knee flexor angles and extensor moments and Fluency (a measure introduced to represent medio-lateral knee control). Statistical differences between ACL and control groups were analyzed using a general linear model univariate analysis, with COM velocity prior to landing as covariate. Hop distance was the smallest for ACLD and largest for CONT (p<0.001; ACLD 57.1±14.1; ACLR 75.1±17.8; CONT 77.7±14.07% height). ACLR used a similar kinematic strategy to CONT, but had a reduced peak knee extensor moment (p<0.001; ACLD 0.32±0.14; ACLR 0.31±0.16; CONT 0.42±0.13 BW.height). Fluency was reduced in both ACLD and ACLR (p=0.006; ACLD 0.13±0.34; ACLR 0.14±0.34; CONT 0.17±0.41s). Clinical practice uses hopping distance to evaluate ACL patients' recovery. This study demonstrated that aspects such as movement strategies and knee control need to be evaluated.

TRAK ontology: defining standard care for the rehabilitation of knee conditions.

In this paper we discuss the design and development of TRAK (Taxonomy for RehAbilitation of Knee conditions), an ontology that formally models information relevant for the rehabilitation of knee conditions. TRAK provides the framework that can be used to collect coded data in sufficient detail to support epidemiologic studies so that the most effective treatment components can be identified, new interventions developed and the quality of future randomized control trials improved to incorporate a control intervention that is well defined and reflects clinical practice. TRAK follows design principles recommended by the Open Biomedical Ontologies (OBO) Foundry. TRAK uses the Basic Formal Ontology (BFO) as the upper-level ontology and refers to other relevant ontologies such as Information Artifact Ontology (IAO), Ontology for General Medical Science (OGMS) and Phenotype And Trait Ontology (PATO). TRAK is orthogonal to other bio-ontologies and represents domain-specific knowledge about treatments and modalities used in rehabilitation of knee conditions. Definitions of typical exercises used as treatment modalities are supported with appropriate illustrations, which can be viewed in the OBO-Edit ontology editor. The vast majority of other classes in TRAK are cross-referenced to the Unified Medical Language System (UMLS) to facilitate future integration with other terminological sources. TRAK is implemented in OBO, a format widely used by the OBO community. TRAK is available for download from http://www.cs.cf.ac.uk/trak. In addition, its public release can be accessed through BioPortal, where it can be browsed, searched and visualized.

Clinical effectiveness of knee rehabilitation techniques and implications for a self-care treatment model.

BACKGROUND: Physiotherapy is a complex intervention frequently recommended for knee conditions. The International Classification of Functioning and Disability (ICF) can be used as a framework to evaluate evidence to develop care models and clinical guidelines. OBJECTIVE: To evaluate the clinical effectiveness of knee rehabilitation modalities categorised according to the ICF domains. DATA SOURCES: A keyword search of Medline, Cinahl, Amed, Embase and Cochrane databases from 1996 to 2010 using terms related to the knee joint and physiotherapeutic interventions. STUDY SELECTION: Reviewer assessment using inclusion/exclusion criteria and a quality assessment tool compiled from the Critical Appraisal Skills Programme Tool, Consort and Cochrane Bone Joint and Muscle Trauma Groups. DATA EXTRACTION: Information about the research design, intervention and subjects was extracted. Outcome measures and findings were categorised according to ICF domains. DATA SYNTHESIS: The majority of studies evaluated exercise. Findings were supportive but specific recommendations were limited due to variations in content and application. There was limited quality research to support the theory that manual therapy, electrotherapy or taping in isolation contributes to recovery. Multimodality physiotherapy programmes were found to be beneficial and to reflect clinical practice, but the effectiveness of each component is unknown. Outcome measures from the participation domain of the ICF were used least frequently and were not generally true measures of participation. CONCLUSION: Development of participation outcome measures is required to evaluate the long-term benefits of interventions. Rehabilitation should be based around delivery of effective exercise programmes incorporating participation outcomes to provide feedback and complement self-care for knee conditions.

Patellofemoral joint compression forces in backward and forward running.

Patellofemoral pain (PFP) is a common injury and increased patellofemoral joint compression forces (PFJCF) may aggravate symptoms. Backward running (BR) has been suggested for exercise with reduced PFJCF. The aims of this study were to (1) investigate if BR had reduced peak PFJCF compared to forward running (FR) at the same speed, and (2) if PFJCF was reduced in BR, to investigate which biomechanical parameters explained this. It was hypothesized that (1) PFJCF would be lower in BR, and (2) that this would coincide with a reduced peak knee moment caused by altered ground reaction forces (GRFs). Twenty healthy subjects ran in forward and backward directions at consistent speed. Kinematic and ground reaction force data were collected; inverse dynamic and PFJCF analyses were performed. PFJCF were higher in FR than BR (4.5±1.5; 3.4±1.4BW; p<0.01). The majority of this difference (93.1%) was predicted by increased knee moments in FR compared to BR (157±54; 124±51 Nm; p<0.01). 54.8% of differences in knee moments could be predicted by the magnitude of the GRF (2.3±0.3; 2.4±0.2BW), knee flexion angle (44±6; 41±7) and center of pressure location on the foot (25±11; 12±6%) at time of peak knee moment. Results were not consistent in all subjects. It was concluded that BR had reduced PFJCF compared to FR. This was caused by an increased knee moment, due to differences in magnitude and location of the GRF vector relative to the knee. BR can therefore be used to exercise with decreased PFJCF.

Plantar pressure relief in the diabetic foot using forefoot offloading shoes.

PURPOSE: Forefoot offloading shoes (FOS) are commonly used in clinical practice for treatment of plantar forefoot ulcers in the diabetic foot. The aim of this study was to assess the offloading efficacy of four different FOS models in comparison with a cast shoe and control shoe. METHODS: In-shoe plantar pressures were measured during walking in each of the six footwear conditions in 24 neuropathic diabetic patients at high risk for plantar foot ulceration. For each of six foot regions, peak pressure, pressure-time integral, and force-time integral were calculated. Load transfer diagrams were developed to assess the footwear mechanisms of action. Perceived walking comfort was measured using a visual analogue scale (VAS). All comparisons between conditions were tested at P<0.05. RESULTS: Peak pressures and pressure-time integrals at the metatarsal heads and hallux regions were significantly reduced (by 38-58%) in all FOS models when compared with the control shoe. The FOS also relieved metatarsal head peak pressure to a significantly larger extent than the cast shoe (approximately 20%). The load transfer diagrams showed a major transfer of approximately 40% of forefoot load to the midfoot explaining the offloading efficacy of the FOS. Perceived walking comfort was significantly lower in the FOS (VAS score 2.7-5.9) when compared with the control shoe (VAS 8.2) and cast shoe (VAS 6.8). CONCLUSIONS: The data showed that all FOS models were effective in their primary goal, relieving forefoot pressure in at-risk neuropathic diabetic patients. Therefore, these shoes may be effective in offloading and healing plantar forefoot ulcers, although the low comfort scores should be considered as this may potentially affect adherence to treatment.

Co-activation: its association with weakness and specific neurological pathology.

BACKGROUND: Net agonist muscle strength is in part determined by the degree of antagonist co-activation. The level of co-activation might vary in different neurological disorders causing weakness or might vary with agonist strength. AIM: This study investigated whether antagonist co-activation changed a) with the degree of muscle weakness and b) with the nature of the neurological lesion causing weakness. METHODS: Measures of isometric quadriceps and hamstrings strength were obtained. Antagonist (hamstring) co-activation during knee extension was calculated as a ratio of hamstrings over quadriceps activity both during an isometric and during a functional sit to stand (STS) task (using kinematics) in groups of patients with extrapyramidal (n = 15), upper motor neuron (UMN) (n = 12), lower motor neuron (LMN) with (n = 18) or without (n = 12) sensory loss, primary muscle or neuromuscular junction disorder (n = 17) and in healthy matched controls (n = 32). Independent t-tests or Mann Witney U tests were used to compare between the groups. Correlations between variables were also investigated. RESULTS: In healthy subjects mean (SD) co-activation of hamstrings during isometric knee extension was 11.8 (6.2)% and during STS was 20.5 (12.9)%. In patients, co-activation ranged from 7 to 17% during isometric knee extension and 15 to 25% during STS. Only the extrapyramidal group had lower co-activation levels than healthy matched controls (p < 0.05). Agonist isometric muscle strength and co-activation correlated only in muscle disease (r = (-)0.6, p < 0.05) and during STS in UMN disorders (r = (-)0.7, p < 0.5). CONCLUSION: It is concluded that antagonist co-activation does not systematically vary with the site of neurological pathology when compared to healthy matched controls or, in most patient groups, with strength. The lower co-activation levels found in the extrapyramidal group require confirmation and further investigation. Co-activation may be relevant to individuals with muscle weakness. Within patient serial studies in the presence of changing muscle strength may help to understand these relationships more clearly.

Plantar pressure in off-loading devices used in diabetic ulcer treatment.

Four off-loading devices used for the treatment of diabetic forefoot ulcers were compared: a custom-molded insole shoe, a cast MABAL shoe, a prefabricated pneumatic walking brace, and a bivalved total contact cast (BTCC). It was anticipated that all devices would significantly reduce forefoot plantar pressure compared with a control shoe. Sixteen healthy volunteers participated. Plantar pressures were evaluated using the Pedar system, while walking speed was determined using an optoelectric timer. Peak pressure (PP) of ten plantar areas and pressure-time integral for the first metatarsal area were analyzed statistically using a repeated measures analysis of variance. Forefoot pressures were significantly reduced compared with the control shoe for all devices (p<0.001). PP was most reduced (by 65.8%) for the BTCC, and pressure-time integral was most reduced for the BTCC and cast MABAL shoe. Small but significant differences between devices in walking speed (p<0.05) could not explain the substantial PP differences between the different devices. Although all off-loading devices resulted in a significant reduction of forefoot plantar pressure, devices differed significantly in the magnitude of pressure reduction. Further research will have to reveal the level of off-loading sufficient for effective treatment of diabetic ulcers.