Medial Wedge Insoles to Improve Gait in Persons After Total Hip Replacement

Study Overview
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Brief Summary
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The study will test the hypothesis, that the use of medial wedge insoles in people participating in comprehensive rehabilitation between 1-6 months after total hip replacement, and not having a varus deformity of the knee or symptomatic arthrosis of the medial knee compartment, will improve patient's functioning, the symmetry of gait and stance compared to persons using sham insoles. The participants will undergo a 6-week program of in-patient rehabilitation aimed at: pharmacologic and non-pharmacologic pain management, improvement of vascular function, cardiopulmonary function, functions of skeletal muscles, range of motion and stability of peripheral joints, gait function, body position. The rehabilitation program will also address individual needs with psychotherapy and vocational therapy. The study will help to identify correlations between gait parameter change and functional improvement during the rehabilitation following THR. Study participants will be provided with individually made corrective medial wedge insoles or sham insoles and instructed to use them during gait training and everyday activities. Functional parameters will be examined at the study entry, at the end of 6 weeks of intervention, and 6 weeks following discharge.

Detailed Description
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Principal indications for total hip replacement (THR) include hip arthritis - degenerative or inflammatory (91%), fractures of femoral neck (5%), avascular necrosis (2%) and hip dysplasia (2%). Weight-bearing exercises (including treadmill training) are important to improve both impairment and ability to function. Rationale of testing the effect of medial wedge insoles after THR: Valgus deformity of the lower limb and insufficiency of the gluteus medius muscle lead to femoral adduction. In patients after a total hip replacement (THR), it will transfer the ground force to the prosthesis cup in the adduction position. The application of corrective insoles is a simple, inexpensive, and non-invasive intervention that may be easily integrated into daily activities to promote health benefits, provide comfort, and prevent acute and chronic injuries, as well as correct biomechanical deficiencies in the musculoskeletal system (including valgus knee ). An important effect of the insoles is to support the preferred movement pattern and, as a result, reduce unnecessary muscle activity in gait, and decrease fatigue and energy expenditure. The use of insoles can therefore be a valuable addition to gait function exercises. Typically, hindfoot corrective insoles are used with a wedge that corrects the heel between 5-15 degrees. Smaller correction wedge angles are unable to correct the valgus moment and affect the center of pressure (CoP) projection during walking, while wedges with a larger correction angle cause discomfort.[5] Medial wedge insoles increase heel inversion, reduce internal tibial rotation, transfer the CoP medially to the knee joint, and increase the knee and hip abduction moment. Insufficiency of the gluteus medius muscle causing pelvic descent and internal rotation of the thigh is typical for hip arthritis, especially after THR using the posterior, posterolateral, or direct lateral approach. It was found that the use of medial wedge insoles promotes the activation of the gluteus medius during dynamic activities, although Bird et al. did not confirm this effect in people with low back pain. Gait symmetry and voluntary walking speed belong to important gait quality parameters measured in patients after THR. Many variables illustrating gait symmetry such as ..step length, step time, time of load changes, foot rotation, time of gait phases, as well as temporal and spatial distribution of forces exerted by specific foot parts may be reliably measured with a treadmill instrumented with force sensors. To identify publications on the effectiveness of corrective insoles after THR, an analysis of the Pubmed, Medline Central, and Scifinder literature databases was carried out using the key phrase: ((hip AND (replace* OR plast* or simple*)) AND ( insole* OR (foot AND correc*))) Identified (November 15, 2019) in databases; Medline Central: 20 records, Scifinder: 73 records, and Pubmed: 66 records. 159 records were reviewed in the title analysis stage, 9 records were eliminated as repeated, 150 records were eliminated as not related to the use of insoles after THR. Evidence on the usefulness of supination insoles in people with arthritis of the lower limb, and also in people after hip arthroplasty is warranted. Study design: A single-center randomized control trial to observe the effect of medial wedge corrective insoles on gait characteristics in persons after THR will be performed in the Rehabilitation Department of the National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland. The trial will involve 100 patients admitted 1-6 months after THR. Consecutive patients fulfilling inclusion criteria will be invited to participate. Participants will be randomly allocated in: Intervention group: the patients will be provided with corrective medial wedge insoles (with hard 10-degree medial wedge) Control group: the patients will be provided with sham medial wedge insoles (with pliable10 degree medial wedge) Participants' age, sex, time since THR, cause of THR, body height and weight, Q angle, intermalleolar distance, and lower extremities length discrepancy will be measured at the study entry. All insoles will be fabricated individually. The design of insoles will comply with the participant's foot size and needs with regard to lower limb length discrepancy elimination. The participants will be recommended to use the insoles during all therapeutic activities and daily activities during the duration of the program. The participants will undergo a 6-week rehabilitation program provided in the Rehabilitation Department of the National Institute of Geriatrics, Rheumatology and Rehabilitation. The program will be aimed at: pharmacologic and non-pharmacologic pain management, improvement of vascular function, cardiopulmonary function, functions of skeletal muscles, range of motion and stability of peripheral joints, gait function, and body position. The rehabilitation program will also address individual needs with psychotherapy and vocational therapy. The following parameters will be assessed by a blinded researcher in the specific time points (1) 3rd day following delivery of insoles; (2) completion of the 6-week rehabilitation program; (3) follow-up 6 weeks after completion of the rehabilitation program: Pain intensity (recently and on average during the preceding week), distress produced by pain (recently and on average during the preceding week), and interference of pain with everyday activities (Pain Rating Scale by the British Pain Society, the Polish version; © The British Pain Society 2006), passive ranges of motion of hip, knee, and ankle joints, pain, stiffness, and physical functional disability (Western Ontario and McMaster Universities - WOMAC scale), osteoarthritis-specific symptoms and physical functional disability (The Lequesne OA index), Gait variables: voluntary speed, step time symmetry, time of load change heel to forefoot symmetry, foot rotation symmetry, length symmetry, step width, stance phase symmetry, load response symmetry, single limb support symmetry, swing phase symmetry and variables illustrating the centre of pressure displacement (length of gait line symmetry, single limb support line symmetry, lateral deviation of the center of pressure, anteroposterior position of the center of pressure) (obtained by Zebris Medical Rehawalk software on HP Cosmos Mercury FDM-THP-M2i treadmill), Stance variables: Centre of Pressure path length, 95% confidence ellipse area, symmetry of average forces, Patient's satisfaction with insoles will be assessed at the completion of the study, Dropout rate and adverse effects. Statistical analysis Normally distributed data will be described by means and standard deviation and statistically tested using the Student t-test and ANOVA. Data not normally distributed will be described by medians and ranges and statistically tested using non-parametric methods such as Wilcoxon's test and the Kruskal-Wallis test. The frequency will be compared using Fisher's exact test. The normality of data will be tested using the Shapiro-Wilk test. The symmetry of gait and stance will be analyzed using different symmetry indices (such as Symmetry ratio, Symmetry index, Gait asymmetry, and Symmetry angle). The correlations between gait parameter change and functional improvement will be analyzed using Spearman's rank correlations coefficient and Fisher's exact test. Significance of the results: The evidence of the beneficial effect of medial wedge insoles on the functioning of patients after THR may result in a recommendation for the use of routine use of such devices after THR. The study will help to identify correlations between gait parameter change and functional improvement during the rehabilitation following THR.

Official Title
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Influence of Medial Wedge Corrective Insoles Versus Sham Insoles on Gait Characteristics in Persons After Total Hip Replacement - Randomized Control Trial

Conditions
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Arthritis of Hip, Fracture of Femur, Aseptic Necrosis, Dysplasia; Hip, Surgical Procedure, Unspecified

Intervention / Treatment
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* Device: medial wedge insoles ((corrective insoles are equipped with hard 10-degree medial wedge, while sham insoles are equipped with pliable 10-degree medial wedge)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Clinical diagnosis of primary or secondary hip coxarthrosis or proxmal hip facture Total Hip replacement made from posterior or lateral surgical approaches Total Hip replacement made less 1-6 months prior to study entry Exclusion Criteria: Total Hip replacement made from anterior or anterolateral approach Total Hip replacement made less than 1 month or more than 6 months prior to study entry Varus knee (Q angle below 5 degrees in males and below 10 degrees in females Symptomatic arthritis of medial compartment of the knee Use of corrective insoles (excluding insoles for limb length discrepancy compensation) Inability to walk for one minute Neurologic conditions History of hip prosthesis dislocation Cognitive dysfunction (MoCa Score below 26) Lack of shoes with a stiff heel counter

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: double-blind sham-controlled single-centre randomized study
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Active Therapy<br>Active comparator will undergo a 6-week in-patient rehabilitation aimed at: pharmacologic and non-pharmacologic pain management, improvement of vascular function, cardiopulmonary function, functions of skeletal muscles, range of motion and stability of peripheral joints, gait function, body position, with treadmill walking training being a mandatory part of the program. The rehabilitation program will also address individual needs with psychotherapy and vocational therapy. Follow-up period will be 6 weeks. For the time of the treatment and follow-up period the treatment arm will be provided with individually made corrective medial wedge insoles to be used during all therapeutic and other everyday activities. | Device: medial wedge insoles ((corrective insoles are equipped with hard 10-degree medial wedge, while sham insoles are equipped with pliable 10-degree medial wedge)<br>* All study participants will be instructed to use insoles for exercising, walking, and other everyday activities.<br>|
| Sham Comparator: Sham Therapy<br>Sham comparator arm will undergo a 6-week in-patient rehabilitation aimed at: pharmacologic and non-pharmacologic pain management, improvement of vascular function, cardiopulmonary function, functions of skeletal muscles, range of motion and stability of peripheral joints, gait function, body position, with treadmill walking training being a mandatory part of the program . The rehabilitation program will also address individual needs with psychotherapy and vocational therapy. Follow-up period will be 6 weeks. For the treatment and follow-up the control arm will be provided with individually made sham insoles to be used during all therapeutic and other everyday activities. | Device: medial wedge insoles ((corrective insoles are equipped with hard 10-degree medial wedge, while sham insoles are equipped with pliable 10-degree medial wedge)<br>* All study participants will be instructed to use insoles for exercising, walking, and other everyday activities.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean change from baseline in pain according to Pain Rating Scale by the British Pain Society on numeric rating scales at 12 weeks | Pain Rating Scale by the British Pain Society, the Polish version; © The British Pain Society 2006 is a self-reported instrument assessing pain intensity (now and on average last week), distress produced by pain (now and on average last week) and interference of pain with everyday activities. The result is presented on five numeric rating scales ranging from 0 (no pain/distress/interference) to 10 (worst possible pain/distress/interference). Change: (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in pain, stiffness, and physical functional disability according to Western Ontario and McMaster Universities - WOMAC scale on 12 weeks | WOMAC scale is a self-reported instrument assessing pain, stiffness, and physical functional disability . The results are presented on a numeric scale between 0 (no symptoms, full physical functionning) and 96 (extremely intensive symptoms, extreme disability). Change: (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in osteoarthritis-specific symptoms and physical functional disability according to Lequesne OA index on 12 weeks | Lequesne OA index is a self-reported instrument assessing osteoarthritis-specific symptoms and physical functional disability. The results are presented on a numeric scale between 0 (no symptoms, full physical functioning) and 24 (extremely intensive symptoms and the worst functioning). Change: (week 12 score - baseline score) | At baseline and on 12 week | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean change from baseline in range of motion of lower extremities on 6 weeks | International SFTR Method of Measuring and Recording of Joint Motion (International Standard Orthopaedic Measurements) will be applied to measure the range of motion of the following joints: hip, knee and ankle in operated and non-perated extremity. The results will be provided in degrees. in operated hips flexion above 90 degrees, abduction, internal rotation will not be measured. Normal ranges of motion values are: Hip (nonoperated) S 15 - 0 - 125 (140 degrees); F 45 - 0 - 25 (70 degrees), R 45 - 0 - 40 (95 degrees); Hip (operated): S 15 - 0 - 90 (105 degrees); F 45 - 0 (45 degrees), R 45 - 0 (45 degrees); Knee: S 0 - 0 - 130 (130 degrees); Ankle: S 20 - 0 - 45 (65 degrees) R 20 - 0 - 40 (60 degrees). Change: (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in range of motion of lower extremities on 12 weeks | International SFTR Method of Measuring and Recording of Joint Motion (International Standard Orthopaedic Measurements) will be applied to measure the range of motion of the following joints: hip, knee and ankle in operated and non-perated extremity. The results will be provided in degrees. in operated hips flexion above 90 degrees, abduction, internal rotation will not be measured. Normal ranges of motion values are: Hip (nonoperated) S 15 - 0 - 125 (140 degrees); F 45 - 0 - 25 (70 degrees), R 45 - 0 - 40 (95 degrees); Hip (operated): S 15 - 0 - 90 (105 degrees); F 45 - 0 (45 degrees), R 45 - 0 (45 degrees); Knee: S 0 - 0 - 130 (130 degrees); Ankle: S 20 - 0 - 45 (65 degrees) R 20 - 0 - 40 (60 degrees). Change: (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in voluntary gait speed on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure voluntary gait speed. The results can range from 0 to 19,9 km/h. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in voluntary gait speed on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure voluntary gait speed. The results can range from 0 to 19,9 km/h. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in step time symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure step time of operated and and non-operated extremity. Symmetry will be calculated as: step time of operated leg/step time of nonperated leg. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in step time symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure step time of operated and and non-operated extremity. Symmetry will be calculated as: step time of operated leg/step time of nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in time of load change heel to forefoot symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure time of load change heel to forefoot. Symmetry will be calculated as: time [sec] of load change heel to forefoot in operated leg/ time of load change heel to forefoot in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in time of load change heel to forefoot symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of load change heel to forefoot. Symmetry will be calculated as: time [sec] of load change heel to forefoot in operated leg/ time of load change heel to forefoot in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in time of maximum force exerted by forefoot symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of maximum force exerted by forefoot. Symmetry will be calculated as: time [sec] of maximum force exerted by forefoot in operated leg/ time of maximum force exerted by forefoot in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in time of maximum force exerted by forefoot symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of maximum force exerted by forefoot. Symmetry will be calculated as: time [sec] of maximum force exerted by forefoot in operated leg/ time of maximum force exerted by forefoot in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in time of maximum force exerted by midfoot symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of maximum force exerted by midfoot. Symmetry will be calculated as: time [sec] of maximum force exerted by midfoot in operated leg/ time of maximum force exerted by midfoot in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in time of maximum force exerted by midfoot symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of maximum force exerted by midfoot. Symmetry will be calculated as: time [sec] of maximum force exerted by midfoot in operated leg/ time of maximum force exerted by midfoot in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in time of maximum force exerted by heel symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of maximum force exerted by heel. Symmetry will be calculated as: time [sec] of maximum force exerted by heel in operated leg/ time of maximum force exerted by heel in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in time of maximum force exerted by heel symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the time of maximum force exerted by heel. Symmetry will be calculated as: time [sec] of maximum force exerted by heel in operated leg/ time of maximum force exerted by heel in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in foot rotation symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the foot rotation. Symmetry will be calculated as: foot rotation [degrees] in operated leg/ foot rotation in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in foot rotation symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the foot rotation. Symmetry will be calculated as: foot rotation [degrees] in operated leg/ foot rotation in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in step length symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the step length. Symmetry will be calculated as: step length [cm] in operated leg/ step length in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in step length symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the step length. Symmetry will be calculated as: step length [cm] in operated leg/ step length in nonperated leg. Possible scores range from 0 to infinity. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in step width on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the step width [cm]. Possible scores range from 0 to 35. Interpretation: interpretation: the lesser step width, the better gait function. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in step width on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the step width [cm]. Possible scores range from 0 to 35. Interpretation: interpretation: the lesser step width, the better gait function. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in the length of gait line marked out by the centre of pressure displacement on walking symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the length of gait line marked out by the centre of pressure displacement on walking. Symmetry will be calculated as: length of gait line [mm] in operated leg/length of gait line in nonperated leg. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in the length of gait line marked out by the centre of pressure displacement on walking symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the length of gait line marked out by the centre of pressure displacement on walking. Symmetry will be calculated as: length of gait line [mm] in operated leg/length of gait line in nonperated leg. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in the single limb support line marked out by the centre of pressure displacement on walking symmetry on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the length of the single limb support line marked out by the centre of pressure displacement on walking. Symmetry will be calculated as: single limb support line [mm] in operated leg/ single limb support line in nonperated leg. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in the single limb support line marked out by the centre of pressure displacement on walking symmetry on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the length of the single limb support line marked out by the centre of pressure displacement on walking. Symmetry will be calculated as: single limb support line [mm] in operated leg/ single limb support line in nonperated leg. Possible scores range from 0 to infinity. Perfect symmetry is when the result is 1.0. Higher or lower values reflect asymmetry. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in lateral deviation of the center of pressure on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the lateral deviation of the center of pressure on walking. Possible scores range from -200 to 200 mm. The lesser lateral deviation, the more symmetrical gait. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in lateral deviation of the center of pressure on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the lateral deviation of the center of pressure on walking. Possible scores range from -200 to 200 mm. The lesser lateral devaition, the more symmetrical gait. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in anteroposterior deviation of the center of pressure on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure anteroposterior deviation of the center of pressure (mm). (Possible scores range from -150 to 150. The lesser anteroposterior deviaton, the more balanced gait. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in anteroposterior deviation of the center of pressure on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure anteroposterior deviation of the center of pressure (mm). (Possible scores range from -150 to 150.The lesser anteroposterior deviaton, the more balanced gait. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in Centre of Pressure path length in stance on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure Centre of Pressure path length in stance (mm). Possible scores range from 0 to 4800. The shorter path, the more balanced stance. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in Centre of Pressure path length in stance on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure Centre of Pressure path length in stance (mm). Possible scores range from 0 to 4800. The shorter path, the more balanced stance. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in 95% confidence ellipse area marked up by the Centre of Pressure displacement in stance on 6 weeks. | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure Centre of Pressure displacement in stance [square mm] Possible scores range from 0 to 125.600. The lesser area, the more stable stance. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in 95% confidence ellipse area marked up by the Centre of Pressure displacement in stance on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure Centre of Pressure displacement in stance [square mm] Possible scores range from 0 to 125.600. The lesser area, the more stable stance. Change (week 12 score - baseline score) | At baseline and on 12 week | 
| Mean change from baseline in the ratio of average forces exerted by operated leg in comparison to non-operated leg during stance on 6 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the he ratio of average forces exerted by operated leg in comparison to non-operated leg during stance. Possible scores range from 0 to 100%. Score 50% - operated leg; 50% non-operated leg reflects symmetrical force distribution. Any deviation reflects stance asymmetry. Change (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in the ratio of average forces exerted by operated leg in comparison to non-operated leg during stance on 12 weeks | HP Cosmos Mercury FDM-THP-M2i treadmill with Zebris Medical Rehawalk software will be used to measure the he ratio of average forces exerted by operated leg in comparison to non-operated leg during stance. Possible scores range from 0 to 100%. Score 50% - operated leg; 50% non-operated leg reflects symmetrical force distribution. Any deviation reflects stance asymmetry.Change (week 12 score - baseline score) | At baseline and on 12 week | 
| User's satisfaction with insoles | (5 point Likert scale will be applied to assess user's satisfaction with insoles the dimension of comfort (how comfortable are the insoles? 2. Very comfortable, 1. Moderately comfortable, 0. Neither comfortable nor uncomfortable, -1. Moderately uncomfortable, -2. Very uncomfortable) and influence on gait (how do insloes influence your gait? 2. Help very much, 1. Help moderately, 0. Neither help nor hamper, -1. Hamper moderately, -2. Hamper very much) | On 12 week | 
| Mean change from baseline in pain according to Pain Rating Scale by the British Pain Society on numeric rating scales at 6 weeks | Pain Rating Scale by the British Pain Society, the Polish version; © The British Pain Society 2006 is a self-reported instrument assessing pain intensity (now and on average last week), distress produced by pain (now and on average last week) and interference of pain with everyday activities. The result is presented on five numeric rating scales ranging from 0 (no pain/distress/interference) to 10 (worst possible pain/distress/interference). Change: (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in pain, stiffness, and physical functional disability according to Western Ontario and McMaster Universities - WOMAC scale on 6 weeks | WOMAC scale is a self-reported instrument assessing pain, stiffness, and physical functional disability. The results are presented on a numeric scale between 0 (no symptoms, full physical functionning) and 96 (extremely intensive symptoms, extreme disability). Change: (week 6 score - baseline score) | At baseline and on 6 week | 
| Mean change from baseline in osteoarthritis-specific symptoms and physical functional disability according to Lequesne OA index on 6 weeks | Lequesne OA index is a self-reported instrument assessing osteoarthritis-specific symptoms and physical functional disability. The results are presented on a numeric scale between 0 (no symptoms, full physical functioning) and 24 (extremely intensive symptoms and the worst functioning). Change: (week 6 score - baseline score) | At baseline and on 6 week | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Total hip replacement, Gait, Insoles, Rehabilitation