Movement Pattern Training in People With Intra-articular, Prearthritic Hip Disorders
Phase: NA
Conditions: Chronic Hip Joint Pain, Prearthritic Hip Disease
Sponsor: Washington University School of Medicine

Movement Pattern Training in People with Intra-articular, Prearthritic Hip Disorders 
 
NCT02913222 
 
9-29-2016 
 

RESEARCH STRATEGY 
A. Significance: Effective treatment of PAHD needed to improve function and prevent or delay hip OA  
 
Intra-articular, prearthritic hip disorders (PAHD) present as hip joint pain and loss of joint function with no 
radiographic evidence of osteoarthritis.18, 48 Associated diagnoses include femoroacetabular impingement, hip 
dysplasia, labral tears and chondral lesions. PAHD result in substantial hip dysfunction in young adults leading 
to significant limitations in walking, sitting and standing,10, 11, 44 thus restricting their ability to work or complete 
everyday tasks. Without proper management, PAHD may progress to hip osteoarthritis (OA),3, 24, 38, 49 a leading 
cause of reduced quality of life and loss of function for older people. 
Current evidence in the treatment of PAHD is limited.2, 4, 41, 53 The preponderance of literature is related to 
surgical interventions and is primarily observational. There are no published clinical trials to compare surgical 
to nonsurgical treatment outcomes. Despite this evidence gap, the number of surgical procedures to treat 
PAHD has grown exponentially9, 39 before clinical trials have established the superiority of surgery over other 
treatment options. Rehabilitation provides a relatively inexpensive alternative to surgery, yet controversy exists 
regarding its effectiveness. Some authors believe rehabilitation can improve function in people with PAHD,13, 33 
however others state that surgery is the best option.28, 30 This controversy may contribute to continued growth 
in the number of surgeries performed, with the potential for surgery to become standard treatment prior to 
rigorous investigation of treatment options. Our long term goal is to develop effective treatment strategies, 
surgical and nonsurgical, for people with PAHD that will improve function and prevent or delay the onset of OA.  
Rehabilitation targeted at modifying abnormal movement 
patterns  may lead to improved function and reduced pain in 
people with PAHD. Abnormal movement patterns, such as 
excessive hip adduction (Fig. 1), may create altered mechanical 
stresses on the hip joint structures, resulting in subsequent injury. 
Kumar et al36 recently reported that excessive hip adduction 
motion during functional testing may be associated with articular 
cartilage damage in the hip joint. In our previous work 
investigating PAHD, we noted that increased hip adduction during 
a single leg squat was associated with lower patient-reported 
function. (See Preliminary studies). Given these novel findings, 
rehabilitation to optimize lower extremity movement patterns 
during functional tasks would be an appropriate approach for 
people with PAHD.  
Movement pattern training (MPT) is an innovative 
rehabilitation approach with the goal to reduce stresses on 
the hip joint by optimizing the biomechanics of functional 
tasks. The key element of MPT is task-specific instruction to 
correct abnormal movement patterns during daily and fitness 
activities. In our previous study, we assessed the feasibility of 
using MPT in addition to hip strengthening for the treatment of 
PAHD.21 After participating in treatment, people with PAHD 
were able to reduce hip adduction during functional tasks21 
and this reduction was associated with improved patient-reported function (See Preliminary studies). 
Surprisingly, hip muscle strength did not improve after treatment, nor was strength associated with functional 
improvement or hip adduction reduction, raising questions about the relationship among hip strength, hip-
specific function and lower extremity movement patterns in people with PAHD.  Although no studies have 
reported the use of MPT in patients with PAHD, similar approaches have been used in low back pain,27, 32, 50, 52 
anterior cruciate ligament tear prevention,29, 47 and patellofemoral pain.43 If determined to be effective in the 
rehabilitation of PAHD, MPT may also serve a role in injury prevention and post-surgical rehabilitation. 
Additionally, we believe MPT can be feasibly implemented into community practice with minimal training and 
equipment. We have successfully implemented MPT in our current clinical practice.     
 
B. Innovation: Novel treatment using movement pattern training to improve function  
The novel theoretical concept of the proposed study is that a person’s movement pattern may 
contribute to the development and persistence of pain related to PAHD. The Physical Stress Theory40 
states that repetitive or prolonged stresses may result in tissue injury if the tissue’s capacity to accept stress is 
exceeded. The Movement System Impairment Theory46 builds upon the Physical Stress Theory by stating that 
Figure 1. Static images representing 
hip motion during single leg squat. Hip 
adduction is represented as the angle 
between line (a) drawn perpendicular 
to the pelvis (dashed line) and line (b) 
bisecting the thigh. A. Abnormal 
movement pattern demonstrating 
excessive hip adduction B. Reduced 
hip adduction after MPT. 

mechanical hip pain is the consequence of repeated use of abnormal movement patterns during daily 
activities. Abnormal movement patterns may create altered mechanical forces on joint structures, thus 
changing the location and magnitude of stress to specific joint tissues, such as the articular cartilage and 
acetabular labrum.46 Repeated loading of hip joint with altered mechanical forces may contribute to cumulative 
tissue stress, micro-trauma, pain and potentially osteoarthritis.15 Until the abnormal movement pattern is 
modified, the hip pain may persist or recur. We have reported extensively on the Movement System 
Impairment Theory in people with low back pain.26, 27, 31, 32, 50, 51  
We will assess the effect of MPT on correcting abnormal movement patterns, reducing pain and improving 
function in people with PAHD. This approach is innovative by focusing treatment on modifying abnormal 
movement patterns that may contribute to altered stresses on the hip joint structures, instead of the traditional 
approach of focusing rehabilitation on isolated physical impairments, such as muscle  weakness14 and limited 
joint flexibility.13, 14  Impairment-based treatment may improve the body’s overall capacity, however may not 
improve hip biomechanics. For example, lower extremity strengthening exercises may increase the muscle’s 
force production capability, however this increased force production capability may not result in improved 
quality of movement during daily tasks. In this proposal, we will perform a multicenter, feasibility RCT to 
compare the efficacy of our novel treatment strategy, MPT, to standard, impairment-based rehabilitation. 
 
C.  Approach 
Overview of the team and the approach 
 
In the future trial, we will need large, generalizable samples that would be difficult, if not impossible, to 
recruit at one site. Therefore two sites, Washington University and University of Pittsburgh, will participate in 
the feasibility RCT. Drs. Harris-Hayes and Fitzgerald will serve as principal investigators (PI). The Steering 
Committee will include the PIs and Drs Clohisy and Schechtman (See Project Leadership Plan). 
 
Washington University, Study Coordinating Center: The Study Coordinating Center (Harris-Hayes, 
Director) will oversee personnel training, protocol implementation, data collection and follow-up. Dr. Harris-
Hayes is an orthopedic physical therapist with a Master’s of Science in Clinical Investigation. As part of her 
training (K23HD067343), she successfully completed an exploratory trial to assess the feasibility of MPT in the 
treatment of PAHD. Washington University provides substantial infrastructure to support this project (See 
Facilities and Other Resources). Our multidisciplinary hip group (See letters Clohisy, Nepple, Prather, Hunt) 
has substantial expertise in PAHD and experience in participant recruitment for clinical research. The Data 
Coordinating Center (Schechtman, director) will administer the study, perform scientific oversight, ensure 
quality control and perform data analysis. 
 
University of Pittsburgh: The Physical Therapy – Clinical and Translational Research Center (PT-CTRC) 
(Fitzgerald, Director) will oversee study implementation at the University of Pittsburg site. Dr. Fitzgerald will 
also guide Dr. Harris-Hayes in developing and implementing methods to optimize treatment fidelity among 
treatment providers. Methods he has used successfully in his previous RCTs will be used in the proposed 
study. Dr. Fitzgerald is an experienced investigator and recognized expert in OA,16 who has conducted multiple 
RCTs examining the effectiveness of rehabilitation related to lower extremity disorders.1, 17, 45 The PT-CTRC 
provides significant infrastructure to perform multicenter clinical trials including access to potential participants, 
facilities, equipment and support for new investigators (See Facilities and Other Resources). 
Timeline: We have developed a Manual of Procedures to facilitate consistency in participant recruitment, 
protocol implementation and data collection across sites. We are developing training modules to optimize the 
treatment providers’ adherence to study protocol. The study planning phase will include a pretrial meeting of 
the Steering Committee and onsite training of study personnel. Methods for the proposed study, described 
below, were optimized in the previous study, therefore we will initiate participant recruitment within one month 
of study start. Recruitment will proceed for 17 months (months 2-18) with the last follow-up being completed by 
month 21. The last 3 months will be used for data analysis and study close-out.  
 
Preliminary studies supporting the approach 
Aim 1: Participant adherence: Based on the previous study (K23), we are confident we will meet recruitment 
and retention goals of the project. In the study, we randomized 35 people with PAHD into an immediate 
treatment group (n=18) or a wait-list control group (n=17). The treatment group participated in 6 sessions of 
MPT. Overall retention rate was 91%; 2 in the treatment group and 1 in the wait-list group did not return after 
baseline testing. Treatment adherence was high; 15 of 16 who participated in treatment attended all 
supervised sessions and 1 attended 5 of 6 sessions. Additionally, 89% of those in the treatment group reported 

completing their home program at least once per day. Using methods optimized in the previous study, we 
anticipate similar adherence in the proposed study. 
 
Aim 2: Post-treatment improvement in outcomes: In our previous study (K23), we used patient-reported 
outcomes and 3D motion analysis to assess post-treatment improvement in function and lower extremity 
movement patterns respectively.  We noted, with baseline assessment, that increased hip adduction motion 
during a single leg squat, may be associated with lower patient-reported function, quantified using the modified 
Harris Hip Score (r = -0.28, P = 0.08) (unpublished data). Compared to wait-list control, those who participated 
in MPT demonstrated improved post-treatment function21 (Fig. 2) that was associated with a reduction in hip 
adduction (r = -0.60, p=0.001) (Fig. 3). Additional preliminary data suggests these post-treatment 
improvements in function are maintained up to 12 months after treatment.20 These preliminary results suggest 
that MPT may be an effective treatment approach for people with PAHD, however comparison to standard 
rehabilitation is needed.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Experimental approach 
Participant Recruitment: 46 participants will be enrolled. To be enrolled, participants must 1) be 15-40 years 
old, 2) report deep hip joint or anterior groin pain, confirmed upon physical exam, 3) report pain > 3/10 and 
present > 3 months and 4) demonstrate functional limitation with modified Harris Hip Score <90. Exclusion 
criteria include 1) previous hip surgery, fracture, pelvic/hip infection, or pain due to high impact trauma, 2) 
inflammatory disease, e.g. rheumatoid arthritis, gout and 3) neurological involvement affecting balance. 
 
General Procedures  
Aim 1: Participant adherence and treatment fidelity: Participant adherence to treatment sessions will be 
documented by the treatment providers. Participants will complete daily logs of home program performance. 
To optimize retention, participants will be contacted at regular intervals by the site-specific research 
coordinator. Any barriers to study participation will be documented and addressed. To optimize treatment 
fidelity among study personnel, we will use training methods established by Dr. Fitzgerald. We also will use the 
treatment fidelity framework developed by the NIH’s Behavioral Change Consortium.7, 8 Treatment providers 
will be contacted monthly to identify barriers to treatment fidelity. Booster sessions to review key components 
of study protocol will be provided at months 9 and 15. 
 
Aim 2: Post-treatment improvement in outcomes (Fig. 4): Informed consent will be obtained prior to testing. 
Participants will complete self-report questionnaires and participate in movement pattern assessment. 
Participants will then be randomized into 1 of 2 treatment groups, movement pattern training (MPT) or standard 
rehabilitation (Control). Both groups will participate in 10 supervised sessions and perform a home program 
Figure 2. Treatment outcomes at baseline and post-
treatment comparing those who received movement pattern 
training compared to those randomized to a waitlist. *p<0.05. 
Figure 3. Association between change in function 
(modified Harris Hip Score (mHHS)) and change in hip 
adduction motion (r = -0.60, p=0.001). Improved function 
was associated with a reduction in hip adduction motion. 
Plot represents the linear regression (solid line) with 95% 
CI (dashed lines).

within a 12 week time frame. At13 weeks after enrollment, participants will return for testing to assess post-
treatment improvements 
 in primary and secondary outcomes.  
 
Specific Procedures (Aims 1 and 2)  
Primary outcome – Function: At pre-treatment 
and post-treatment testing, participants will 
complete the Hip disability and Osteoarthritis 
Outcome Score (HOOS),42 a reliable and valid34 
hip-specific, patient reported outcome measure. 
Basic demographic, medical history and medication 
use will also be collected. (Appendix 1). All 
questionnaire responses will be collected and 
managed using Research Electronic Data Capture 
(REDCap, See Facilities and Other Resources) 
system hosted at Washington University. We will 
use the tailored design method of survey 
procedures, used in our previous study, to motivate 
participants to respond.12   
 
 Minimum important change (MIC) for HOOS 
subscales has not been established for patients 
undergoing non-surgical management for PAHD. 
Using values established for people who have 
undergone arthroscopic surgery,34 the MIC values 
for HOOS subscales of ADL and Symptoms are 6 
and 9 respectively. In our preliminary work, 
statistically significant differences exceeding MIC 
were found in HOOS ADL and Symptoms, with 
those participating in MPT demonstrating greater 
improvement at follow up compared to those in the 
wait-list group (Fig. 2). 
 
Secondary outcome – Movement pattern: We will use a digital camera to acquire 2D hip motion while 
participants complete tasks of varying difficulty: step down, single leg squat, drop vertical jump. Markers will be 
placed on anatomical landmarks of the pelvis and thigh to assist with hip angle measurement. Previously 
published procedures25 for camera placement and participant positioning will be used to optimize between-site 
data collection and reduce the effect of projection angles on the 2D measures. Participants will practice each 
movement prior to testing. We will then collect 3 trials of each movement. Commercially available software will 
be used to measure peak hip adduction motion. All measurements will be completed by trained personnel at 
Washington University, who will be blinded to treatment group.  
 
In our preliminary work, we used 3D kinematic methods to quantify hip motion during the single leg squat. 
For the current study, we chose to use a 2D method that can be easily replicated with simple equipment in the 
clinical setting. To assess our ability to predict 3D peak hip adduction angle using our proposed 2D method, we 
used digital videos synchronized to the 3D kinematic data collection. Using data from 12 randomly selected 
participants, we found the correlation between 2D and 3D peak hip adduction to be high (r = 0.85, P < 0.001). 
Test-retest reliability of our 2D method is excellent (ICC3,3 = 0.996); standard error of measurement of 0.47°. 
 
Randomization: Participants will be randomized to 1 of 2 treatment groups in a 1:1 ratio stratified by sex and 
HOOS Symptoms quartile (as determined from the preliminary data) within each site. Within each stratum, 
participants will be allocated using a variable block size so that the desired allocation ratio will be maintained at 
intervals throughout the recruitment process. Randomization sequences will be generated a priori using a 
formal probability model and will be elicited from the data capture system. Given the nature of the intervention, 
it is not possible to blind the treatment providers or participants to treatment assignment. Study personnel 
performing the assessments or the movement pattern measurements will be blinded to group assignment.  
 
Treatment: Treatment for both groups will include 10 supervised sessions over 12 weeks. After randomization, 
Figure 4. Study flow diagram. CONSORT flow diagram 
adapted. WU = Washington University; UP = University of 
Pittsburgh. Note: Using additional support from WU, 6 & 12 
month data will be collected during and after the funding 
period to assess durability of post-treatment improvement.  

scheduling for participants, the treating physical therapists will be trained and tested in standardized 
procedures for both treatment arms. Both treatment arms will include assessment of patient goals, patient 
education and instruction in a home program. Patient education will focus on patient-specific tasks, identified 
by the participant to be symptom-producing. Based on participant responses during our preliminary work, 
patient-specific tasks included work-related and fitness activities, such as running, cycling and swimming. 
Participant independence and adherence will be documented (Appendix 2).22 A brief description of the 
treatment approaches are provided below.  
 
Movement pattern training (MPT) (Appendix 3): Focus will be on task-specific training to improve lower 
extremity movement patterns during basic functional tasks, such as sit to stand and stair negotiation, and  
reported patient-specific tasks. Patient education will include instruction in abnormal movement patterns and 
methods to optimize their movement pattern during each task. Exercises will include repeated practice of 
functional tasks using optimized movement patterns. Verbal cues and visual aids, such as a mirror, will be 
used to assist the participant. Based on the participant’s performance, the difficulty of the task-specific 
activities will be progressed by varying the repetitions performed, increasing the load or changing the support 
surface. The home program will consist of repeated practice of tasks performed during supervised sessions. 
 
Standard rehabilitation (Control) (Appendix 4): Focus will be on progressive lower extremity and trunk 
strengthening and lower extremity flexibility. Patient education will include instruction to modify intensity, 
frequency or duration of patient-specific tasks. Using current clinical practice guidelines14 and previous 
reports,6, 53 strengthening and flexibility exercises will be prescribed and progressed by varying the repetitions 
performed or increasing the load. The home program will include exercises performed during supervised 
sessions.  
 
Post-treatment assessment: Participants will return for questionnaire completion and movement pattern 
assessment immediately after treatment. We will compare pre-treatment measures to post-treatment measures 
of both treatment groups to assess change in functional ability (HOOS) and movement patterns. Additionally, 
participants will complete a questionnaire developed to determine barriers to treatment adherence and to 
assess 1) treatment receipt, ‘did the participant receive the treatment as intended’ and 2) treatment enactment, 
‘was the participant able to successfully implement their new skills’.7, 8 To assess sustained effects of 
treatment, participants enrolled at the Washington University site will return for questionnaire completion and 
laboratory testing 1-2 years after treatment 
 
Additional measures: We will collect additional measures, to assist in the future trial development. To assess 
the feasibility of using PROMIS, the NIH-funded Patient-Reported Outcomes Measurement Information System 
for people with PAHD, we will use the computer-adapted version of the physical function and mobility domains.  
Using previously reported methods,23 we will assess hip muscle strength pre- and post-treatment. Finally, 
using additional funding from Washington University (See letter, Earhart), participants will complete study 
questionnaires, electronically administered, 6 and 12 months after treatment to assess durability of post-
treatment improvement.   
 
Sample size considerations: With a sample size of 46 (23/group), the 95% confidence bounds (CBs) around 
our overall rates of adherence and retention will be between 78% and 96%, meaning that estimates will be 
within 9% of the true rate. The within site and within group estimates of adherence will be within 13% of the 
true rate. These calculations assume that the observed rates will be at least 90%, which is reasonable to 
expect based on our preliminary data. Aim 2 will estimate intervention effect sizes and as such, the study is not 
designed to generate definitive results. However, with at least 20 participants/group completing pre- and post-
testing, the study will have 80% power to detect large effect sizes of 0.9 or above, with 95% CBs between 0.27 
and 1.53. We note that preliminary data for the primary outcomes indicate that approximately 50% of the 
variance in change is explained by the pre-treatment value, and thus power and precision will be increased by 
including this covariate in the analyses. 
 
We anticipate no problems enrolling sufficient participants for this feasibilty study. We were able to enroll 3-
5 participants per month during our previous study. To improve our likelihood of meeting recruitment goals, we 
have added the University of Pittsburgh site and established collaborations with additional healthcare providers 
in St. Louis. We have also removed the restriction from the previous study for body mass index (previously <30 
kg/m2 required for kinematic testing). Support from the Data Coordination Center (Schechtmen, Director) will 
assist in optimizing retention rate and patient follow-up. Additionally, we will provide compensation of $25/hour 
to offset travel effort and costs related to the testing sessions and treatment will be provided at no charge. 

 
Statistical Analysis: The primary data analyses for Aim 1 will be descriptive, and include reporting the rate of 
recruitment, screening, and enrollment for all potential participants considered for the study; and reasons for 
non-enrollment. Adherence, retention, and fidelity rates will be categorized using the specified thresholds and 
reported with 95% CBs. Uncategorized rates will be compared between sites and groups by Wilcoxon’s test. 
Aim 2 will generate estimates of effect sizes. We will report change between pre-and post-treatment with 95% 
CBs. Inferential analyses will compare the change in response to treatment using analysis of covariance 
(ANCOVA) where change is the dependent variable and the pre-treatment value is the covariate. Accounting 
for variation in pre-treatment function will increase the precision of the between-group comparisons and also 
adjust the treatment effect estimates for possible imbalances between groups. If statistical assumptions are not 
satisfied, transformations will be explored or nonparametric covariance analyses35 will be used. 
 
Data Management and Quality Control: Study data will be electronically captured using the REDCap system 
hosted in a limited access data center managed by the Data Coordinating Center. Additional quality control 
programs will verify that study identification numbers are accurately labeled, evaluate consistency over time, 
and check for incomplete or overdue data. Routine reporting will monitor recruitment and retention, overall 
quality, and protocol deviations. Throughout the study, standardization of procedures across sites will be 
ensured by dynamic training and monitoring that includes site visits and remote auditing. 
 
Limitations and Alternative Approaches: We have proposed this feasibility RCT to assess the ability to 
perform a multicenter RCT. Multicenter studies have unique challenges, however we believe this is a strength 
of our study by allowing us to achieve large, generalizable samples. We have developed a team with individual 
strengths that, when brought together, will optimize our ability to successfully complete this project and 
subsequent studies. Although a new investigator, Dr. Harris-Hayes has demonstrated her capability to lead a 
project by completing an exploratory RCT (manuscript in review) during her K23 training grant. Drs. Fitzgerald 
and Schechtman are experienced investigators, with significant experience implementing multicenter studies. 
Dr. Clohisy is well-recognized for his clinical expertise in PAHD and has an established research agenda with 
the goal of improving patient outcomes through investigation of nonsurgical and surgical treatment strategies.  
 
Given our preliminary data, we expect those receiving MPT will report improved function after treatment. It 
is possible those receiving the standard rehabilitation will report similar improvements. Although unexpected, 
this finding would be important to demonstrate that nonsurgical management may be an option for people with 
PAHD. Study data will then be used to guide the development of future improved treatment strategies. If we 
find similar improvements in both groups, it is likely some participants will respond favorably to the treatment 
approach they received, while others remain unchanged or possibly worsen. Secondary analysis of patient-
specific factors and movement pattern assessment may identify subgroups of people with PAHD who would 
respond to different types of treatment.5  
We did not include imaging in this study. Imaging would provide useful information about bony 
abnormalities19, 37 and structural disease associated with PAHD, however would be cost-prohibitive for this 
feasibility study. In our preliminary work, we did not find an association between patient-reported function and 
bony abnormalities. We therefore chose to focus on the abnormal movement pattern in this study. Imaging to 
assess bony abnormalities and structure disease will be included in the future, definitive trial. 
 
Significance and future directions: Information from the current study regarding the participants’ ability to 
adhere to treatment, the treatment providers’ ability to adhere to the treatment protocol and effect size 
estimates will guide the future, large RCT. Should the feasibility study indicate that modifications are needed, 
these will be made prior to the large RCT. Feedback from study participants and the treatment providers will be 
used to improve participants adherence and treatment fidelity. The future RCT will include assessment of 
patient-reported function and movement patterns from the proposed study and bony abnormalities. A better 
understanding of the association among these factors and treatment prognosis will help us develop improved 
treatment strategies and to better match treatment to patients.  
 
Intra-articular, prearthritic hip disorders result in significant limitations in the young adult and are likely 
precursors to osteoarthritis. MPT is an innovative treatment approach with the potential to optimize treatment 
outcomes, nonsurgical and surgical, for people with PAHD. Further, MPT may provide a strategy for injury 
prevention, particularly those injuries of insidious nature. Ultimately this work will lead to better overall 
outcomes, reduced healthcare cost and reduced patient burden.  

Appendix 3: Movement Pattern Training Protocol 
 
 
 
 
3.1 Task-specific instructions 
• 
Handouts provided to participants to reinforce performance of task-specific modifications 
during daily activities. 
3.2 Progression table for task-specific training 
• 
Provides overview of progression for task-specific training. 
 
 

Appendix 3.1 
Sitting Down From Standing Position 
1. Stand with knees touching back of 
chair, feet hip‐width apart. 
 
2.  Bend at your hips and knees while 
simultaneously contracting your thighs 
to slowly lower yourself onto the chair. 
3a. Keep your knees aligned 
with your feet.   
 
3b.  Don’t allow knees to roll in.  
Squeezing your buttocks will prevent 
your knees from coming together. 
 
4. Sit down onto the front of the chair and 
scoot to back of chair 
    
 
If can’t bend hip past 90 degrees, straddle 
feet so the ___________ foot is back and        
the _____________ foot is forward. 

 
 
Standing Up From Sitting Position 
1. Position your feet hip‐width apart and 
far enough under you so there is a good 
bend at your knees. 
2. Scoot to the front of the chair.  Position 
your feet slightly behind your knees. 
 
3. Use your thighs and 
buttocks to lift your body up 
off the chair while shifting 
weight forward.  Avoid pulling 
your knees back to meet your 
body. 
4. Keep the knees aligned with 
the toes.  Do not allow the 
knees to roll in.  
5. Final position of your knee 
should be relaxed with  
a slight bend. 
 
 
If you can’t bend hip past 90 degrees, straddle feet so  
the ______________ foot is back  and the ______________ foot is forward. 
               
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Walking 
 
Focus on moving in a heel to toe 
fashion, keeping feet hip width apart.  
Avoid pivoting on a fixed foot. 
 
Try to let your heel land softly on 
the ground.  Contract your seat 
muscles as the heel hits the ground 
to align knee over foot. 
 
Avoid completely straightening your 
leg from the point your heel hits the 
ground to the point where your toes 
leave the ground; always have a bend 
in your knee.  
__decrease speed 
__decrease stride length 
 
Make sure you “lift your heel” to 
help make pushing off with your 
toes easier.  Taking slightly 
shorter steps can also help. 
 

Ascending Stairs 
Lean forward and use your thigh and buttock to move your body forward 
onto the next stair.  Avoid pulling your knee back to meet the body.  Instead 
propel the body forward on to the next stair.  
Squeeze your buttock to prevent 
your knee from turning inward. 
 
Correct 
Don’t let your knee roll in or your 
pelvis tilt. 
 
Incorrect 
Note:  If ascending stairs is painful, use a handrail or step up each step with your non‐
painful leg first 

Descending Stairs 
Lean forward and bend your standing leg 
to slowly lower yourself onto the next 
stair. 
Squeeze your buttock to prevent your 
knee from turning inward. 
 
Correct 
 
Don’t let your knee roll in or your pelvis 
tilt. 
 
 
Incorrect 
Note: If descending stairs causes pain, lead each stair’s 
 descent with the painful hip. 

 
Weight Shifts 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Weight shifting with unilateral gluteal contraction of the stance limb 
Purposes: 
•To improve the performance of the hip external rotator and abductor muscles. 
•To prevent compensatory movements of the hip, pelvis, and spine.  
•To prevent the thigh from turning inward. 
1. Stand with both feet relatively close together. 
2. Shift your weight to one leg. 
3. Tighten your buttock muscle on the side of your stance leg. 
4. Repeat to the opposite leg. 
5. Alternate the weight shift from one leg to the other. 
6. Keep your pelvis level and trunk upright. 
7. Do not let your opposite hip drop. 
8. Do not let your knee turn inward. 
9. You may place your hands on your pelvis to monitor your motion. 
Repeat 10-20 times on each leg. Perform 2 sets. 
*this exercise may be used frequently throughout the day to improve contraction and 
reduce pain. 

Single leg stance 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Single leg stance 
Purposes: 
•To improve the performance of the hip external rotator and abductor muscles. 
•To prevent compensatory movements of the hip, pelvis, and spine.  
1. Stand with both feet relatively close together and knees “unlocked” 
2. Shift your weight to one leg and tighten your buttock muscle on the side of your stance leg. 
3. Lift your opposite leg in front of you as if marching in place. 
4. Repeat to the opposite leg. 
5. Keep your pelvis level and trunk upright. 
6. Do not let your opposite hip drop or knee turn inward. 
7. You may place your hands on your pelvis to monitor your motion. 
*Optional: Hold onto countertop for balance 
Repeat 10-20 times. Perform 2 sets. 

 
Single Leg Squat 
Lean forward and bend your standing leg 
to slowly lower yourself and return to the 
starting position. 
Squeeze your buttock to prevent your 
knee from turning inward. Keep your 
trunk in the upright position. 
 
Correct 
 
Don’t let your knee roll in or your trunk 
bend to the side. 
 
 
 
Incorrect 
 

 
 
 
Standing 
Don’t stand with your knees locked.  Allow 
there to be a slight bend in your knees. 
  
 
Correct                  Incorrect 
Don’t stand with your hips swayed forward 
or your shoulders swayed back behind 
your hips. 
   
 
Correct 
 
 
Incorrect 
Don’t stand with weight on one leg: 
 
Incorrect 
Instead, stand with equal weight 
on both legs with your feet hip 
width apart: 
 
Correct 
Avoid standing for prolonged periods. 
__Allow feet to point out if femoral retroversion 
                __Allow feet to point in if excessive femoral anteversion 

Sitting 
Position yourself so that your knees are aligned 
with your feet.  While sitting, your feet should be 
supported (flat on the floor). Back rest should be 
supportive. 
Don’t sit with your knees 
higher than hips. 
 
Don’t sit in a “W” position 
Don’t cross your legs in any of the following positions: 
 
 
 
 
(a) Leg around thigh. 
 (b) Thigh over thigh.  
 (c) Ankle over knee        (d) Sitting on one leg 
Your therapist may instruct you to 
sit with your hips higher than your 
knees.  You may need to raise your 
chair or use a pillow or wedge in 
your chair. 
Don’t rest feet on toes 
pulled underneath chair.
 

Sleeping 
When sleeping on your side, use pillows between your knees  
to keep your legs parallel to the floor: 
 
 
 
 
Avoid extreme hip flexion or rotation: 
 
 
 
 
 
   Incorrect  
 
 
 
 
           Incorrect 
Additional instructions: 
___________ When sleeping on your stomach, place a pillow under your hips. 
___________ When sleeping on your back, place a pillow under your knees. 
___________ When sleeping on your side, you may reduce pressure on your hip by 
_____placing towel rolls above and below the hip bone. 
_____ a towel roll under the waist. 
Incorrect 
 
 
 
 
 
 
Correct 

 
 
Appendix 3.2 
Task-specific training progression   
Task - Movements 
Level 1 
Level 2 
Level 3 
Level 4 
Level 5 
 
1. Sit to Stand 
Stand to Sit* 
 
2. Walking/Running** 
 
 
 
3. Ascending stairs* 
 
 
4. Descending stairs* 
 
 
5. Single leg activities 
 
 
1. Regular seat height 
   
 
2. Patient-preferred 
speed 
 
 
3. 6-8” step up 
  
 
4. 6-8” step down 
 
 
5. Weight shift 
 
 
 
 
1. Regular seat height 
with resistance   
  
2. Patient-preferred 
    speed, increase time 
  
 
3. 6-8” step up with 
resistance 
 
4. 6-8” step down with 
resistance 
 
5. Single leg stance 
with hold 
 
1. Lower seat height with 
resistance 
 
2. Fast-walk  
 
 
 
3. 6-8” step up with 
resistance 
  
4. 6-8” step down with 
resistance  
 
5. Single leg squat with 
hand support 
 
1. Varying seat height 
with resistance 
    
2. Walk-Run (if patient 
goal), otherwise 
increase time walking 
 
3. 8-10” step up 
 
 
4. 8-10” step down 
 
 
5. Single leg squat 
 
 
 
1. Varying seat height with 
increased resistance 
 
2. Run (if patient goal), 
otherwise increase time 
walking 
 
3. 8-10” step up with 
resistance 
        
4. 8-10” step down with 
resistance 
 
5. Single leg squat with 
resistance 
6. Patient-specific 
tasks 
 
Tasks will be identified by the participant during their baseline assessment. Activities typically include work-related activities such as 
standing and sitting or fitness/sport activities. Tasks will be practiced and progressed in difficulty based on participant performance. 
For example, see walking above for progression to running. Cycling mechanics will be observed and modified; progression will 
include increase in time and speed.  
Task - Position 
 
1. Standing 
2. Sitting 
3. Sleeping 
Participant will be provided instruction during the initial 2 visits. Each activity will be assessed during follow up visits, until the 
participant is independent in the task. To be independent in the task, the participant must verbalize and demonstrate proper 
performance. 
*Parameters: Perform 2-4 sets, 8-12 reps 1x/day. Resistance can be provided with theraband, ankle weights or weight equipment. Participant is 
progressed to the next level when they can perform 3 sets of 8-10 repetitions with ease and demonstrating good mechanics at the hip and knee. 
**Walking/Running Parameters: Participants will be progressed to the next level when they can perform with good mechanics at the hip and knee 
and report no worsening of their symptoms.    
 

 
 
 
 
 
 
 
 
 
                 
 
   
Appendix 4: Standard Rehabilitation Protocol 
 
 
 
 
4.1 Exercise instructions 
• 
Provides exercise instructions given to participant. Pictures are also provided to assist 
with independent performance of home program. 
4.2 Progression table for exercise 
• 
Provides overview of exercise progression. 
 

 
 
 
 
 
 
 
 
 
                 
 
      
Appendix 4.1 
(All exercises printed with permission) 
 
Hip Abductors – Level 1 
 
 
 
 
 
Hip Abductors – Level 2 
 
 
 
Hip Abductors – Level 3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hip Abduction in Supine 
Purpose: To improve performance of hip abductor muscles. 
 
1. Lay on your back with your legs straight and close together. 
2. Contract your buttock muscle to slide your leg out to the side.  
3. Return your leg to the starting position.  
 
Perform 2-4 sets, 8-12 reps 1x/day 
Hip Abduction in Side Lying with Knee Flexed 
Purpose: To improve the performance of the hip abductor muscles.  
 
1. From side lying, bend both hips and knees. 
2. Lift top knee towards the ceiling while keeping your ankles 
together. 
3. Return top knee to starting position. 
Perform 2-4 sets, 8-12 reps 1x/day 
 
Hip Abduction in Side Lying with Hip Extended 
Purpose: To improve the performance of the hip abductor muscles. 
  
1. Lying on your side, bend the bottom hip and knee. 
2. Straighten your top hip and knee. 
3. Lift top leg towards ceiling. 
4. Return leg to starting position. 
 
Perform 2-4 sets, 8-12 reps 1x/day 
 

 
 
 
 
 
 
 
 
 
                 
 
      
Hip Abductors – Level 4 and 5 
  
 
 
Hip Extensors – Level 1 
 
 
 
Hip Extensors – Level 2 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
Bridge 
Purpose: To improve the performance of the hip extensors. 
 
1. Lay on your back with knees bent. 
2. Squeeze glutes and lift hips off of the table. 
3. Return hips to starting position. 
 
Perform 2-4 sets, 8-12 reps 1x/day 
Hip Abduction in Standing with Resistance 
Purpose: To improve the performance of the hip abductor muscles.  
 
1. From standing, lift your leg out to the side.  
2. Return leg to the starting position. 
Perform 2-4 sets, 8-12 reps 1x/day 
Level 5: Increase resistance 
Hip Extension—Prone with Knee Extended 
Purpose: To improve the performance of the hip extensors. 
 
1. Squeeze the gluteal muscle and raise thigh off the floor as you lift 
toward the ceiling. 
2. Slowly lower leg back down and relax. 
 
Perform 2-4 sets, 8-12 reps 1x/day 

 
 
 
 
 
 
 
 
 
                 
 
      
Hip Extensors – Level 3 
 
 
  
 
 
 
 
 
 
 
 
 
Hip Extensors – Level 4 
 
 
 
 
 
 
  
 
 
 
 
 
Hip Extensors – Level 5 
 
 
 
 
 
 
 
 
 
 
 
Hip Extension—Standing with Resistance 
Purpose: To improve the performance of the hip extensors.  
 
1. Bring the ankle behind the body.  
2. Slowly return back to start position.  
Perform 2-4 sets, 8-12 reps 1x/day 
Progression: Increase resistance. 
Squat  
Purpose: To improve the performance of the hip extensors.  
1. Stand with both feet shoulder width apart. 
2. Perform a squat. Keep your back straight as you “sit” back. 
3. You may place your arms in front of you to maintain balance. 
Perform 2-4 sets, 8-12 reps 1x/day 
 
Lunges 
Purpose: To improve the performance of the hip extensors.  
 
1. Stand with feet shoulder width apart. Step forward into a lunge, 
keeping your knee straight in front of you. Push back to start position 
with front leg.  
2. Your knee should never pass your toes. 
Perform 2-4 sets, 8-12 reps 1x/day  
Progression: hold weights in hands while performing the lunge. 

 
 
 
 
 
 
 
 
 
                 
 
      
Hip Flexors – Level 1 
 
Hip Flexors – Level 2 and 3 
 
 
Hip Flexors – Level 4 and 5 
 
 
Hip Flexion- Standing Position with Resistance 
Purpose: To improve the performance of the hip flexors. 
 
1. From standing, bring leg straight in front of you. 
2. Return leg to starting position 
 
Perform 2-4 sets, 8-12 reps 1x/day  
Level 5: Increase resistance. 
Hip Flexion- Supine Position  
Purpose: To improve the performance of the hip flexors. 
1. Lay on your back with legs straight. 
2. Slide one heel up towards your trunk keeping your heel on the table. 
3. Return heel back to starting position. 
Perform 2-4 sets, 8-12 reps 1x/day  
Hip Flexion- Supine Position 
Purpose:  To improve the performance of the hip flexors. 
1. Lay on back with one leg straight and one leg bent. 
2. Lift the straight leg towards the ceiling. 
3. Return leg to starting position. 
Perform 2-4 sets, 8-12 reps 1x/day  
Level 3: Add resistance/weight. 

 
 
 
 
 
 
 
 
 
                 
 
      
Hip Adductors – Level 1  
 
 
Hip Adductors – Level 2 and 3 
 
 
 
 
 
 
 
 
Hip Adductors – Level 4 and 5 
 
 
 
 
 
Hip Adduction—Side Lying 
Purpose: To improve the performance of the hip adductors.  
 
1. Lie on side with bottom leg straight. 
2. Bend the knee of the top leg over the bottom leg. 
3. Raise the bottom leg up toward the ceiling. 
4. Slowly lower back down. 
Perform 2-4 sets, 8-12 reps 1x/day  
Level 3: Use resistance with this exercise.  
Hip Adduction in Standing with Resistance 
Purpose: To improve the performance of the hip abductor muscles.  
 
1. From standing, lift your leg across your body.  
2. Return leg to the starting position. 
Perform 2-4 sets, 8-12 reps 1x/day  
Level 5: Increase resistance. 
 
Hip Adduction—Sitting  
Purpose: To improve the performance of the hip adductors.  
 
1. Sit with knees slightly apart. 
2. Place hands on the inside of your knees. 
3. Squeeze the thighs together, but resist the motion with your hands. 
4. Hold for 5 seconds, then slowly relax. 
Perform 2-4 sets, 8-12 reps 1x/day  

 
 
 
 
 
 
 
 
 
                 
 
      
Hip Internal Rotators – Level 1 and 2 
 
 
 
 
 
Hip Internal Rotators – Level 3+ 
 
  
 
 
Hip External Rotators – Level 1 and 2 
 
 
 
 
Hip Internal Rotation—Prone  
Purpose: To improve the performance of the hip internal rotators.  
 
1. Lay on your stomach and bend your knee. 
2. Rotate your hip by allowing the foot of the bent knee to move away 
from your other leg. 
3. Return slowly back to the start position.  
Perform 2-4 sets, 8-12 reps 1x/day  
Level 1: no resistance 
Level 2: may use theraband with increasing resistance to progress this 
exercise. 
Hip Internal Rotation—Sitting 
Purpose: To improve the performance of the hip internal rotators.  
 
1. Sit at the edge of a table or chair with feet hanging above the floor. 
2. Rotate your hip by allowing the foot of one leg to move away from 
your other leg. 
3. Return slowly back to the start position.  
Perform 2-4 sets, 8-12 reps 1x/day  
Level 4 and above: Increase resistance of theraband with this exercise. 
Isometric Hip ER in Prone 
Purpose: To improve the performance of the hip external rotator muscles. 
 
1. Lay on your stomach and bend your knee. 
2. Rotate your hip by allowing the foot of the bent knee to move toward 
your other leg. 
3. Return slowly back to the start position.  
Perform 2-4 sets, 8-12 reps 1x/day  
Level 1: no resistance 
Level 2: may use theraband with increasing resistance to progress this 
exercise. 

 
 
 
 
 
 
 
 
 
                 
 
      
Hip External Rotators – Level 3+ 
 
 
Trunk – Level 1 
 
 
 
 
 
Trunk – Level 2 
 
 
 
 
 
Hip ER in Sitting  
Purpose: To improve the performance of the hip external rotator muscles. 
 
1. While keeping your thigh on the supporting surface, rotate your hip so 
that your foot moves in toward the other leg. 
2. Return leg slowly to starting position. 
Perform 2-4 sets, 8-12 reps 1x/day  
Level 4 and above: Increase resistance of theraband with this exercise.  
Plank – On Knees 
Purpose: To improve trunk stability.  
 
1. Lying face down, support your body weight on your forearms and 
knees.  
2. Tighten your stomach muscles while keeping your neck and back 
straight. 
3. Your trunk should not rotate and the back should remain flat from 
shoulders to hips. Do not hike hips in the air.  
Perform 2-4 sets, 30-60 second holds 1x/day  
Plank – On Toes 
Purpose: To improve trunk stability.  
 
1. Lying face down, support your body weight on your forearms and 
toes.  
2. Tighten your stomach muscles while keeping your neck and back 
straight. 
3. Your trunk should not rotate and the back should remain flat from 
shoulders to hips. Do not hike hips in the air.  
Perform 2-4 sets, 30-60 second holds 1x/day  

 
 
 
 
 
 
 
 
 
                 
 
      
Trunk – Level 3 
 
 
 
 
 
Side Trunk – Level 1 
 
 
 
 
Side Trunk – Level 2 
 
 
 
 
Plank on Toes with Leg Lift 
Purpose: To improve trunk stability with limb movement.  
 
1. Lying face down, support your body weight on your forearms and 
toes.  
2. Tighten your stomach muscles while keeping your neck and back 
straight. 
3. Your trunk should not rotate and the back should remain flat from 
shoulders to hips. Do not hike hips in the air.  
4. Lift on leg back up into the air.  
Perform 2-4 sets, 30-60 second holds 1x/day  
Side Plank – On Knees 
Purpose: To improve trunk stability.  
 
1. Lie on your side with your knees bent.  
2. Support your body weight on your forearm and knees.  
3. Tighten your stomach muscles while keeping your neck and back 
straight. 
4. Your trunk should not rotate and the back should remain flat from 
shoulders to hips. Do not hike hips in the air.  
Perform 2-4 sets, 30-60 second holds 1x/day  
Side Plank – On One Knee 
Purposes: To improve trunk stability.  
 
1. Lie on your side with your bottom knee bent and the top one straight. 
2. Support your body weight on your forearm and knee.  
3. Tighten your stomach muscles while keeping your neck and back 
straight. 
4. Your trunk should not rotate and the back should remain flat from 
shoulders to hips. Do not hike hips in the air.  
Perform 2-4 sets, 30-60 second holds 1x/day  

 
 
 
 
 
 
 
 
 
                 
 
      
Side Trunk – Level 3 
 
 
 
 
Flexibility – Hamstring Stretch 
 
 
 
Flexibility – Calf Stretch 
 
 
 
 
Side Plank – Legs Straight 
Purpose: To improve trunk stability.  
 
1. Lie on your side with both legs straight.  
2. Support your body weight on your forearm and feet.  
3. Tighten your stomach muscles while keeping your neck and back 
straight. 
4. Your trunk should not rotate and the back should remain flat from 
shoulders to hips. Do not hike hips in the air.  
Perform 2-4 sets, 30-60 second holds 1x/day  
Doorway Hamstring Stretch 
Purpose: To improve the flexibility of the hamstrings.   
 
1. Lie on your back near a doorway 
2. Keeping your knee straight, bring your leg up along the door frame. 
3. You should feel the stretch in the back of your thigh. 
4. Make sure your lower leg stays flat on the floor. 
5. Stretch to the point of feeling tightness or slight discomfort. 
 
Hold 30 secs, 2-4 reps (can adjust hold and reps, but should accumulate 
60 sec of stretch total), perform 1x/day 
Calf Stretch – Standing 
Purpose: To improve the flexibility of the calf muscles.   
 
1. Standing with feet staggered/ one foot in front of the other. 
2. Lean forward with hands on the wall, keeping the back foot in contact 
with the ground.  
3. If you keep the back knee straight you are stretching the gastroc 
muscles. If you bend the back knee slightly, you are stretching the 
soleus.   
4. Hold for 30 seconds, then slowly shift weight back to normal standing.  
5. Stretch to the point of feeling tightness or slight discomfort. 
Hold 30 secs, 2-4 reps (can adjust hold and reps, but should accumulate 
60 sec of stretch total), perform 1x/day 

 
 
 
 
 
 
 
 
 
                 
 
      
Flexibility – Hip Flexors Stretch 
 
 
 
Flexibility – Piriformis Stretch 
 
 
Hip Flexors Stretch – Kneeling/Standing 
Purpose: To stretch the hip flexor muscles. 
 
1. Get into the kneeling/standing position with one leg in front of the 
other. 
2. Keeping back upright, lean weight forward towards front leg. 
3. Hold stretch for 30 seconds, then repeat for the other leg. 
4. Stretch to the point of feeling tightness or slight discomfort. 
Hold 30 secs, 2-4 reps (can adjust hold and reps, but should accumulate 
60 sec of stretch total), perform 1x/day 
Piriformis Stretch 
Purpose: To improve the flexibility of the piriformis. 
 
1. Lying on your back with knees bent.  
2. Cross the ankle of the leg to be stretched over the other knee. Put 
your arms around the thigh as shown. 
3. Bring your thigh towards your stomach. Feel the stretch in your 
buttock. 
4. Stretch to the point of feeling tightness or slight discomfort 
Hold 30 secs, 2-4 reps (can adjust hold and reps, but should accumulate 
60 sec of stretch total), perform 1x/day 

 
 
Appendix 4.2  
Exercise progression  
Target Muscles –
Strength 
Level 1 
Level 2 
Level 3 
Level 4 
Level 5 
 
1. Hip Abductors* 
 
 
2. Hip Extensors* 
 
 
3. Hip Flexors* 
 
 
4. Hip Adductors* 
 
 
5. Hip Internal Rotators* 
 
 
6. Hip External Rotators*
 
 
7. Trunk** 
 
8. Side Trunk** 
 
 
1. Hip Abda in supine 
   
 
2. Bridges 
 
 
3. Heel slide 
  
 
4. Hip  Addd isometrics 
in sitting 
 
5. Hip IRe in prone 
 
 
6. Hip ERf in prone 
 
 
7. Plank on knees 
 
8. Side plank on knees 
 
1. Hip Abd in side lying 
with knee flexed   
  
2. Hip Extb in prone 
  
 
3. Straight leg raise 
 
 
4. Hip Add in side lying 
 
 
5. Hip IR in prone with 
resistance 
 
6. Hip ER in prone with 
resistance 
 
7. Plank on toes 
 
8. Side plank on one 
knee 
 
1. Hip Abd in side lying 
with hip extended 
 
2. Hip Ext in standing 
with resistance 
 
3. Straight leg raise with 
resistance 
 
4. Hip Add in side lying 
with resistance 
 
5. Hip IR in sitting with 
resistance 
 
6. Hip ER in sitting with 
resistance 
 
7. Plank on toes with leg 
lift 
8. Side plank legs 
straight 
 
1. Hip Abd in standing 
with resistance 
    
2. Squats 
 
 
3. Hip Flexc in standing 
with resistance 
 
4. Hip Add in standing 
with resistance 
 
5. Hip IR in sitting; 
progress resistance 
 
6. Hip ER in sitting with 
resistance 
 
 
 
 
 
 
1. Hip Abd in standing; 
progress resistance 
 
2. Lunge 
 
 
3. Hip Flex in standing; 
progress resistance 
        
4. Hip Add in standing; 
progress resistance 
 
5. Hip IR in sitting; 
progress resistance 
 
6. Hip ER in sitting with 
resistance  
Target Muscles – 
Flexibility 
 
 
 
 
 
1. Hamstrings 
2. Calves 
3. Hip Flexors 
4. Piriformis 
Hold 30 seconds 2-4 reps (can adjust hold and reps, but should accumulate 60 seconds of stretch total), perform 1x/day 
aAbd = Abduction, bExt = Extension, cFlex = Flexion, dAdd = Adduction, eIR = Internal Rotation, fER = External Rotation  
*Strength Parameters: Perform 2-4 sets, 8-12 reps 1x/day. Resistance can be provided with theraband, ankle weights or weight equipment. 
Participant is progressed to the next level of exercise when they can perform 3 sets of 8-10 repetitions independently and with ease.  
**Trunk Parameters: Perform 2-4 sets, 30-60 second holds 1x/day.