No description available.

Objective: The primary aim of this research was to examine the temporal pattern of neuromuscular quadriceps deficits in both the involved and uninvolved limbs of patients assigned to the control group after anterior cruciate ligament reconstruction (ACLr), by assessing quadriceps strength, voluntary activation, and corticomotor excitability prior to surgery (baseline), three months after ACLr, and six months after ACLr. A secondary aim of this research was to determine whether quadriceps strength, voluntary activation, and/or corticomotor excitability assessed in patients prior to ACLr and/or at three months after surgery, is predictive of lower extremity postural control and/or self-reported function at six months after ACLr. Lastly, a tertiary aim of this research was to determine if a 12-week home-based neuromuscular electrical stimulation (Home-NMES) program elicits greater bilateral improvements in quadriceps strength, voluntary activation, and corticomotor excitability of patients at three and six months after ACLr compared to a 12-week standard home-exercise program (control group). Participants: Fifty patients scheduled to undergo unilateral ACLr were randomly allocated to the home-NMES group (19 Female, 6 Male; age: 18.9 ± 5.4 years; height: 170.8 ± 9.7 cm; weight: 74.6 ± 18.5 kg; 28.0±20.0 days-post-injury) or control group (14 Female, 11 Male; age: 19.4 ± 4.5 years; height: 171.1 ± 11.5 cm; weight: 70.7 ± 11.9 kg). Methods: A randomized clinical trial design was used in this study. Prior to ACLr, isometric quadriceps strength and voluntary quadriceps activation were assessed in both limbs of patients, and corticomotor excitability was assessed in the involved limb. Three days after ACLr, both groups were instructed to begin their allocated interventions. The Home-NMES group administered NMES to their involved limb’s quadriceps three sessions a day for 15 minutes, and five days a week for 12 weeks using a portable NMES device. The control group was treated according to the current standard-of-care, but they were also instructed to perform volitional isometric quadriceps contractions for the same duration and frequency as the Home-Based NMES protocol. The outcomes measures were reassessed in both groups at three and six months post-ACLr. Main Outcome Measures: Quadriceps strength and voluntary activation were assessed using maximal voluntary isometric contractions and the superimposed burst technique, respectively. Normalized peak knee extension torque and central activation ratio were used to quantify isometric quadriceps strength and activation, respectively. Corticomotor excitability was evaluated with transcranial magnetic stimulation, and quantified with active motor threshold). The Y-balance test anterior reach (YBT-A) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were used to assess the patients lower extremity knee function at six months post-ACLr. Statistical Analyses: Specific Aim 1: A 2x3 (limb x time) mixed model, ANOVA with repeated measures was performed in the control group to assess differences between the involved limb and the uninvolved limb for isometric quadriceps strength, and voluntary quadriceps activation over time. A one-way mixed model, ANOVA with repeated measures was performed in the control group to assess differences in corticomotor excitability over time. Post-hoc comparisons were performed when appropriate. Specific Aim 2: Separate, mixed model, linear regression analyses were performed in the control group (involved limb) to determine the effect that the neuromuscular quadriceps outcome measures assessed at baseline and 3 months post-ACLr, had on lower extremity knee functional outcome measures assessed at 6 months post-ACLr. Specific Aim 3: A 2x2x3 (group x limb x time) mixed model, ANOVA with repeated measures was performed to assess group differences between the involved limb and the uninvolved limb in isometric quadriceps strength, and voluntary quadriceps activation over time. A 2x3 (group x time) mixed model, ANOVA with repeated measures was performed to assess group differences in corticomotor excitability over time. Post-hoc comparisons were performed when appropriate. Results: Aim 1: Patients demonstrated lower quadriceps strength on their involved limb compared to their uninvolved limb at baseline, three months post-ACLr, and six months post-ACLr. Quadriceps strength progressively decreased in the involved limb of patients from baseline to 3 months post-ACLr, baseline to 6 months post-ACLr, and increased from 3 months to 6 months post-ACLr. Quadriceps strength was also decreased in the uninvolved limb of patients from baseline to 6 months post-ACLr. ). Irrespective of when it was assessed, voluntary quadriceps activation was higher in the involved limb of patients compared to their uninvolved limb. There were no changes in corticomotor excitability of the involved limb over time. Specific Aim 2: The quadriceps strength of patients at three months post-ACLr had a significant positive effect on their 6-month YBT-A performance KOOS score. ). Neither voluntary quadriceps activation or corticomotor excitability or AMT (at baseline or 3-month post-ACLr) had a significant effect on any of the 6-month lower extremity functional outcome measures. Specific Aim 3: Irrespective of limb or when it was assessed, quadriceps strength was higher in the control group compared to the Home-NMES group. Both groups demonstrated lower quadriceps strength on their involved limbs compared to their uninvolved limbs at baseline, three months post-ACLr, and six months post-ACLr. Quadriceps progressively decreased in the involved limbs of both groups from baseline to three months post-ACLr and baseline to six months post-ACLr, and increased from three months to six months post- ACLr. At baseline, voluntary quadriceps activation was higher in the involved limbs of both groups compared to their uninvolved limbs. There were no group differences or changes over time observed in the involved limb of both groups with corticomotor excitability. Conclusion: Although quadriceps weakness is more apparent in the involved limb of patients after ACLr, the quadriceps strength of their uninvolved limb was also affected. Clinicians are encouraged to not rely on a quadriceps strength limb symmetry index when making return-sport-decisions for their patients after recovering from ACLr. The quadriceps in the uninvolved limb of patients demonstrated more inhibition, which may explain the quadriceps strength deficits observed in the uninvolved limb of patients following ACLr. To reduce the risk of subsequent injury upon return-to-sport and protect against the development of knee OA, we recommend that clinicians incorporate bilateral interventions aimed at restoring quadriceps strength and disinhibiting the quadriceps. Intensive quadriceps strengthening should be performed in the early stages of ACLr rehabilitation, so that lower extremity function can be improved in patients later on. Lastly, the effectiveness of home-based NMES as a modality for restoring quadriceps strength and activation in patients after ACLr is inconclusive. Home-based NMES provides patients with the ability to receive higher doses of NMES to the quadriceps; but its effectiveness may be limited by low contraction intensities and poor treatment compliance in patients.

Conventional anterior cruciate ligament (ACL) reconstruction grafts have not been able to replicate the mechanical behaviour of the native ACL, reproduce normal knee mechanics and kinematics, or prevent degenerative disease progression of the knee. The aim of this thesis was to investigate a novel ACL design to more closely mimic the normal mechanical behaviour of the ACL, reconstruct the isometric ACL fibre and potentially reproduce the normal kinematics and mechanics of the knee. The designed artificial ACL reconstruction (ACLR) system could be used as a stand-alone device or in conjunction with a total knee replacement (TKR). The nominated design option for the ACLR system consisted of a connecting cord made of ultra-high molecular weight polyethylene (UHMWPE) fibres and an elastic system made of cobalt-chrome-molybdenum (CoCrMo) alloy with similar load-elongation characteristics to the native ACL. The design requirements were defined based on the mechanical properties of the native ACL, size constraints from the bony geometry and TKR components, and the location of the isometric fibres of the native ACL. The in vitro mechanical tests performed in this project on the designed cord showed a 2-3 times greater ultimate tensile load compared to the ACL in young human cadavers. The decreasing creep modulus of the UHMWPE cord under fatigue loading in simulated body conditions (3118 MPa at 6.5×10⁶ cycle) indicated nominal creep and stabilised mechanical properties by the 3000^th loading cycle. To replicate the non-linear stiffness of the ACL with ~38 N mm^-1 toe and ~100 N mm^-1 linear regions, the artificial ACLR device consisted of a femoral spring (~60 N mm^-1) in series with a tibial spring (~100 N mm^-1) and a connecting cord (~2000 N mm^-1). Two helical springs in series were used for the stand-alone ACLR, whereas a helical spring in series with a spiral spring was designed for the ACLR-TKR. As both the helical and spiral springs had a constant stiffness, stop mechanisms were added to the springs to create a non-linear stiffness and control the maximum safe deformation limit of each spring. To understand the mechanical behaviour of the reconstructed isometric fibre of the ACL, passive and loaded motions were simulated in 18 sets of segmented MRI models of healthy human knees. Constant load and elongation was observed throughout flexion during the passive movements, whereas maximal load and elongation in the reconstructed ACL was identified at 50 º of flexion during loaded motion. An ACL attachment placement sensitivity study, conducted in this project to assess the effect of surgical implantation error on the behaviour of the reconstructed ACL, revealed that misplacement of the femoral attachment would significantly influence the load-elongation of the reconstructed ACL. Finite element (FE) models of the designed ACLR devices enabled their behaviour under simulated axial loading, squatting and the Lachman test to be assessed. Both ACLR devices successfully reproduced stiffness of the native ACL with a multi-linear stiffness curve, however, elongation greater than 3.1 mm could not be achieved. It can be concluded that the designed artificial ACLR devices were able to mimic the mechanical behaviour of the ACL provided it was positioned at the isometric attachment points; potentially enabling achievement of more natural kinematics and mechanics of the reconstructed knee. However, ACL placement was shown to have a significant impact on the behaviour of the reconstructed ACL, therefore, placement error may over-constrain the joint. For this reason, a more forgiving design with a lower stiffness and a larger deformation limit would be advised.

Fu, Sai Chuen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 173-195). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese; appendixes includes Chinese.

Approximately 200,000 anterior cruciate ligament (ACL) injuries occur each year with about 100,000 of these injuries undergoing reconstruction (ACLR). The impetus of ACLR is to allow previously high functioning, physically active individuals to return to desired levels of sports participation and to engage in recommended levels of physical activity. However, 1 out of 3 patients after ACLR fail to return to competitive levels of sport and meet recommended levels of physical activity. Injury-related fear has been cited as the primary barrier for failure to return to sport. However, the research has been primarily qualitative in nature and limited research has quantitatively examined the impact of injury-related fear on return to sport and physical activity engagement in this population. In addition to quantifying the impact of injury-related fear, no research has examined the underlying neural substrates associated with injury-related fear after ACLR. Previous research has demonstrated that patients after ACLR undergo neuroplasticity in sensorimotor regions of the brain and exhibit changes in neurocognitive functioning. Despite previous research in other musculoskeletal pathologies demonstrating neuroplasticity in emotional regulation centers of the brain, no research has examined these brain regions in patients after ACLR. Furthermore, previous research in healthy athletes has suggested that psychosocial impairments can lead to changes in neurocognitive functioning, including reaction time. Understanding these neural substrates could provide insight into appropriate intervention strategies to decrease injury-related fear, increase return to sport and physical activity engagement, and potentially improve neurocognitive functioning in patients after ACLR. The purpose of this dissertation was to further investigate the effects of injury-related fear on patients after ACLR and to determine the efficacy of a cognitive behavioral intervention to decrease injury-related fear in this population. The purposes of these studies were to determine whether patient-based, specifically psychological, and functional outcomes were associated with return to sport and physical activity levels in individuals with a history of ACLR, to determine differences in brain activation patterns when exposed to fear-eliciting stimuli in individuals with a history of ACLR compared healthy matched controls, and to determine the efficacy of in vivo exposure therapy on self-reported fear and reaction times in participants post-ACLR. The results of these studies indicate that injury-related fear was quantitatively associated with return to sport and physical activity engagement in patients after ACLR. Additionally, individuals with a history of ACLR activated emotional regulation centers of the brain in greater depth when compared to healthy matched controls. Lastly, in vivo exposure therapy decreased self-reported injury-related fear for specific functional tasks but did not improve general fear response or reaction time in post-ACLR participants. The results of these studies objectively elucidate the negative impact of injury-related fear in patients with a history of ACLR.

This is an interdisciplinary research project in which the methods of Industrial and Product Design Engineering are focused upon a problem in Orthopaedics. One of the most controversial areas in Orthopaedics is the reconstruction of the anterior cruciate ligament (ACL). The current twin-instrument method for locating the ACL is difficult for surgeons with fewer than 500 surgical experiences. This was clearly demonstrated by Kohn, Busche and Cans (1995), and confirmed by Sommer, Friederich and Muller (2000), Sudhahar, Glasgow and Donell (2004), and Kuga, Yasuda, Hata et al. (2004). The above research indicates that the problem is not only one of anatomical location, but of how the operation takes place. The aim of the research was, therefore, to develop a new and improved surgical instrument and technique for locating the ACL anatomical landmarks. The research described in this thesis employs a number of design methods that can be used separately or in combination (hybrid process). They form the theory base that guides the design process. This allows the designer to engage in a flexible process that is effective in finding design solutions to the problem. Within this process, iterative case studies were employed in order to design a new surgical device for ACL reconstruction. The thesis describes a series of designed devices (case studies) that were iteratively developed and surgically tested, leading to a penultimate device. This latter device was tested via a number of surgical operations. The device provides a new method for externally locating the internal ACL attachment points. The research has resulted in a commercial association with Smith and Nephew Surgical Australia and BrainLAB AG Germany for the commercialisation of this technique. At the time of writing, the next stage of research and development is under way. This is using a frameless computer-aided image guidance system in the place of X-ray.

Background: Evidence indicates that an external focus (EF) of attention on the intended effect of one’s movement results in better motor performance and motor control than an internal focus (IF) on one’s own body. Despite this, an IF is predominantly encouraged through instructions and feedback provided by clinicians during sports and rehabilitation from injuries such as anterior cruciate ligament (ACL) injury. Aim: The aim of this pilot study was to investigate the influence of EF and IF on motor control and performance on a bilateral leg extension and flexion task. The secondary aim was to investigate potential differences in the outcomes between a control group and a group with ACL reconstruction (ACLR). Method: Fourteen controls and four individuals with ACLR performed a bilateral leg extension and flexion task with instructions that encouraged either an IF, EF or neutral focus (NF) of attention. The instructions encouraged participants to either keep the individual tubes located on the footplates under the soles of the feet (EF) or the feet themselves (IF) level with each other. A three-dimensional motion capture system was used to record kinematics. Motor control was assessed based on the movement smoothness according to the knee angular velocity profile and performance was assessed based on the absolute mean deviation of the tubes/footplates from parallel. Results: For the control group, IF instructions resulted in significantly better motor control than EF instructions for left knee movement smoothness (p=0.02) and NF instructions resulted in significantly better motor control than EF on a majority of dependent variables. Conclusion: For our task, EF instructions did not result in better outcomes compared to IF instructions which might be explained because the task was proprioceptive demanding with less involvement of the vision. The reason for better motor control with NF instructions compared to EF instructions might be because of differences in angular velocity and instructions between conditions.

No description available.

Bakgrund: Främre korsbandsskador är vanliga i idrotten och korsbandsrekonstruktion bedöms främst vara aktuellt för unga personer med höga krav på knäfunktion, till exempel elitidrottare. Rehabiliteringen är en lång och krävande process där både fysiologiska och psykologiska aspekter är viktiga. Motivation är associerat med återgång till idrott och elitidrottare återgår till idrott på samma nivå i högre utsträckning jämfört med icke-elitidrottare. Däremot är det oklart vad som motiverar elitidrottaren till rehabilitering. Syfte: Syftet var att undersöka sex elitidrottares upplevelser och erfarenheter kring motivation till rehabilitering i syfte att återgå till elitidrott efter en främre korsbandsrekonstruktion.Metod:Kvalitativ deskriptiv design. Semistrukturerade intervjuer genomfördes och bearbetades med kvalitativ innehållsanalys. Totalt intervjuades sex elitidrottande män och kvinnor inom idrotterna ishockey, innebandy och basket. Resultat: Analysen resulterade i sex kategorier: ”Rehabiliteringen är ett maraton och inte en sprint”, ”Viktigt med stöd från laget och omgivningen”, ”Olika psykologiska aspekter hos elitidrottare påverkar”, ”Att vara, eller inte vara elitidrottare”, ”Motivation är sällan svart eller vitt”, ”Fysioterapeutens viktiga roll under rehabiliteringen” samt femton underkategorier. Konklusion: Stöd från laget, anhöriga och vänner var viktigt, likaså samarbetet med fysioterapeuten som också ledde till en känsla av trygghet. Informanterna beskrev att motivation kom både inifrån och utifrån. Resultatet kan hjälpa såväl fysioterapeuter som idrottare att identifiera och applicera strategier för att öka motivationen under rehabiliteringen. / Background: Anterior cruciate ligament injuries are common in sports and reconstructions are largely considered relevant for young people with high demands on knee function e.g., elite athletes. Rehabilitation is a long and demanding process in which physical and psychological aspects are important. Motivation is associated with return to sport and elite athletes return to sport at the same level in greater extent than non-elite-athletes. However, it is unclear what motivates the elite athletes to rehabilitate.  Purpose: The aim was to investigate six elite athletes’ views and experiences about motivation to rehabilitation with the purpose to return to elite sports after an anterior cruciate ligament reconstruction.  Method: Qualitative descriptive design. Semi-structured interviews that were analyzed trough a qualitative content analysis. Six elite athletes from the sports ice-hockey, floorball and basketball were interviewed.Result:The analysis resulted in six categories: ”Rehabilitation is a marathon and not a sprint”, ”The importance of support from the team and the surrounding”, “Different psychological aspects in elite athletes influence”, To be, or not to be an elite athlete”, ”Motivation is rarely black or white”, ”The physiotherapist´s important role during the rehabilitation” and fifteen sub-categories. Conclusion: Support from the team, relatives and friends was considered important as well as collaboration with the physiotherapist which also led to a feeling of security. The informants described that motivation was both internal and external. The result may assist both physiotherapist and athletes to identify and apply strategies to increase motivation during rehabilitation.

The purpose of this dissertation was to study the effects of graft pretension in anterior cruciate ligament (ACL) reconstruction through a series of experiments. First, an in vitro study of 5 human knees was conducted to determine if intact joint kinematics could be restored when using the ideal graft - the intrinsic ACL. The ACL tibial insertion site was freed, and pretensions of 0, 10, 20, 30, and 40 N were applied to the ligament using a custom designed load cell connection. Kinematics during a simulated active extension were compared to those of the intact knee. Intact knee kinematics were not restored. Pretensions that best restored tibial anterior/posterior translation and internal/external rotation ranged from 0-40 N. Furthermore, the pretensions that best restored these kinematic variables were widely disparate in two specimens. Second, the in vitro kinematics during a simulated active extension of human and porcine knees were compared and contrasted both prior to and following transection of the ACL. The ACL limited: (1) tibial anterior translation in both species, (2) tibial internal rotation in humans, and (3) tibial external rotation in pigs. Differences in kinematic patterns for tibial internal/external rotation and abduction/adduction between the species was explained by requirements for biped and quadruped stances. Third, the mechanical characteristics of porcine patellar tendon (PT) were investigated by uniaxial tensile testing at two strain rates. Patella-PT-tibia complexes from freshly sacrificed skeletally immature and mature animals were loaded to failure at elongation rates of 20 and 200 mm/min. Both strain rate and skeletal maturity significantly affected failure mode, tangent modulus, and ultimate stress of the tendons, and hence are important considerations in the mechanical evaluation of porcine PT. Fourth, ACL reconstructions were performed using pretensions of 10 or 20 N in an in vivo porcine model with a specially designed load cell/telemetry system to monitor graft load. Graft pretension was seen to increase during fixation with interference screws. Following sacrifice at 4 weeks, tissues were mechanically, histologically, and biochemically analyzed. A pretension of 20 N resulted in a tissue more similar to the intrinsic ACL. / Ph. D.