EFFECTS OF MOTOR IMAGERY INTERVENTION ON FUNCTIONAL RECOVERY FOLLOWING TOTAL KNEE ARTHROPLASTYPIŠOT, RADO (Mentor) Hadžić, Vedran (Komentor) total knee arthroplastyphysical performancestrengthmental simulationOsteoarthritis (OA) is a major cause of disability among older adults. When conservative treatments have failed, a total knee arthroplasty (TKA) is a surgical replacement of a degenerated or malformed joint, that is prescribed to patients with OA. TKA successfully relieves pain, corrects the deformity, and improves function. However, most patients never reach the functional level of the age-matched OA asymptomatic population even years after surgery. Quadriceps strength is a major determinant of general physical function following TKA. In the early post-surgery period, patients experience loss of more than half of their pre-surgery strength, a likely consequence of the alterations of motor control at a central level induced by surgery. Motor imagery (MI), mental simulation of a movement without overt muscle contraction, has been largely used to improve general motor tasks. However, this is still to be investigated in TKA patients. Therefore, the primary aim of the present doctoral thesis is to investigate how and to which extent will MI practice (MIp) intervention influence the recovery of neuromuscular and locomotor function following TKA. More specifically, we aimed to examine effects of MIp on a) maximal isometric strength (MVS) of knee extensors; b) maximal voluntary activation (VMA) level; c) Spatio-temporal gait parameters during different gait velocities under single- and dual-task conditions; d) self-reported measures of lower extremity function such as Oxford Knee Score (OKS) and lower extremity functional score (LEFS); e) contractile muscle parameters; f) electromechanical efficiency index (EME); and g) pain level assessed by Visual Analogue Scale (VAS). Given that Questionnaires used in planned research were not cross-culturally adapted to Slovenian speaking community, and their psychometric properties were not investigated we aimed answer to this challenge as well. To answer on objectives/question mentioned above a different types of research were conducted. Study I aimed to investigate whether MI intervention can meaningfully improve maximal voluntary strength in healthy adults and to investigate the dose-response relationship of MIp. Meta-analysis showed (i) that MI is an effective method for maximal strength development in healthy adults, while there is no convincing evidence that the combination of MI and physical practice is more effective than conventional strength training (CST) alone; (ii) The following MI variables were associated with enhanced strength: a training period of 4 weeks, a training frequency of three sessions per week, a training volume of two to three sets, 25 repetitions per set, and single session duration of 15 minutes; (iii) Cortical representation of the involved muscle has minor modulating power, suggesting that both large and small cortically represented muscles can almost equally benefit from MI. In Study II, a systematic review of literature was conducted to investigate alterations of maximal voluntary strength (MVS), voluntary muscle activation (VMA), and the cross-sectional area (CSA) of the quadriceps muscle, up to 33 months after the TKA. Results showed that quadriceps MVS markedly declines in the early postoperative period, after which it slowly and linearly recovers over time. However, the same phenomenon was not observed for VMA and CSA, which were not significantly altered after the TKA. Furthermore, a meta-regression analysis revealed that the change in VMA accounted for 39% of the relative change in quadriceps strength in the early postoperative period. Patients treated with TKA had considerable weakness of the quadriceps muscle, which was detectable up to 3 months after surgery, regarding rehabilitation practice applied. In Study III, we aimed to validate the Slovenian version of Motor Imagery Questionnaire (MIQ-3). Results showed that the Slovenian translation of the MIQ-3 is culturally and linguistically equivalent to the original English version. In study IV, we aimed to validate cross-culturally adapted versions of both the OKS and LEFS questionnaires to Slovenian language speaking community and to determine their feasibility, test-retest reliability, internal consistency and congruent validity. In study V, we aimed to investigate whether a MI focused on maximal isometric knee extension strength, causes additional specific and general adaptations upon neuromuscular and functional variables when compared routine physical therapy only, in patients submitted to TKA. Results showed that significant differences in treatment effects were observed for the MIp group compared to CON: the MIp showed less strength decrease; faster self-selected speed under single and dual-task conditions; brisk-pace gait speed during single and dual-task conditions; improved chair sit-to-stand performance; and a higher score on MI ability questionnaires for kinaesthetic imagery and internal visual imagery scales, respectively. In study VI, we aimed to investigate whether MIp will influence the contractile muscle properties of OA patients following TKA. Results did not show significant alterations of either parameter when compared to the CON group, that performed routine physical therapy only. However, when data were pooled results showed that TKA treatment altered physical function as well as contractile properties of the main skeletal muscles surrounding the involved joint in the early period after surgery; however, alterations showed to be both limb and muscle-specific. These findings might provide clinicians and physiotherapist with additional information on how to adapt rehabilitation to the needs of an individual patient. The overall findings explain how MIp can be used to improve motor performance in patients following TKA. Also, it illustrates that central neural processes underlying such improvements. Finally, in study VII, we explored whether the addition of MIp to routine physical therapy reduces the deterioration of quadriceps MVS and VMA as well as other variables related to motor performance in patients after TKA. Significantly better rehabilitation outcomes were evident on the operated leg for the MIp group compared to CON: at POST, the MIp showed lower strength decrease and unaltered VMA, that was significantly greater than CON. There were no significant differences in knee flexion and extension range of motion and pain level. Further, MIp patients performed better in Timed up to go test and reported better OKS scores. The non-operated leg showed no significant differences in any outcomes at POST. In addition, multiple linear regression analysis showed that the failure of VMA explained 47% of the quadriceps muscle strength loss, with no significant difference in perceived level of pain. Overall findings support that motor imagery practice as a type of cognitive training can be used as an efficient method to enhance motor performance in both healthy individuals and patients who were scheduled for total knee arthroplasty. Additionally, we validated and cross-culturally adapted Motor Imagery Questionnaire (MIQ-3), Oxford Knee Score (OKS) and Lower Extremity Functional Score (LEFS) questionnaires to Slovenian language speaking community. These new tools will enable all practitioners and scientist from the field to successfully conduct and evaluate the results of their practices and/or research.20202020-10-23 07:15:08Doktorsko delo/naloga121691sl