Movement pattern training compared with standard strengthening and flexibility among patients with hip-related groin pain: results of a pilot multicentre randomised clinical trial

Study design, setting and patient involvement

This study was a pilot, multicentre RCT (figure 1). Data collection and treatment occurred at The Movement Science Research Center at Washington University’s Program in Physical Therapy and The Physical Therapy – Clinical and Translational Research Center at the University of Pittsburgh. Washington University served as the coordinating centre and single site institutional review board (IRB). This study was approved by Human Research Protection Offices of Washington University and University of Pittsburgh. All patients signed an informed consent statement prior to participating. Patients were not involved in the design, recruitment or conduct of the study.

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Manual of operations (MOP) development and training

An MOP was developed to document standard methods for all study components. To optimise treatment fidelity, we used the treatment fidelity framework developed by National Institutes of Health’s Behavioral Change Consortium.11 12 Active ingredients believed to affect patient outcomes for each treatment arm were identified and operationally defined. Each treatment protocol was reviewed by experts at both sites to ensure it reflected the underlying theory of its respective approach. The first author led onsite training for examiners (n=2) and treating PTs (n=5); all were PTs with 6–27 years of experience. Training included review and discussion of the MOP, patient scenario role plays to demonstrate assessment and treatment concepts and discussion to identify barriers to study protocol performance and patient treatment adherence. Training time totalled 16 hours per site.

Participants

Patients were recruited between January 2017 and February 2018, from healthcare clinics; research volunteer databases; social media; and other written communications. To be eligible, patients had to be 15–40 years old; report deep hip joint or anterior groin pain that was reproduced with flexion, adduction, internal rotation impingement test13; report pain ≥3/10 and present ≥3 months; and demonstrate functional limitation with modified Harris Hip Score14 <90. Exclusion criteria included previous hip surgery, fracture, infection or pain due to high impact trauma; diagnosed with Legg-Calve-Perthes disease or slipped capital femoral epiphysis; inflammatory disease; neurological involvement affecting balance; pain, numbness or tingling that radiates into thigh; pregnancy; and screening tests indicating hip pain was referred from the spine.

Assessment (baseline and post-treatment)

Patients who passed initial screening were scheduled for clinical examination, which included assessment of final screening criteria and, if the patient was determined to be eligible, baseline assessment. Patients completed self-report questionnaires and participated in assessment of movement patterns and hip strength. Patients were then randomised into MoveTrain or Standard. Thirteen weeks after enrolment, patients returned for post-treatment testing.

Treatments

Treatments were delivered according to the Template for intervention Description and Replication Guidelines.15 Treatment for both groups included 10 supervised sessions over 12 weeks and daily home exercise programme (HEP). Both treatment arms included assessment of patient goals, patient education and HEP instruction. Patient education focused on patient-specific tasks, which were identified using the Patient Specific Functional Scale (PSFS).16 A brief description of each treatment arm is provided below.

Movement pattern training (MoveTrain) (online supplementary appendix A): treatment focus was on task-specific training to improve lower extremity kinematics during functional and patient-specific tasks. Patient education included instruction in abnormal movement patterns and methods to optimise movement patterns during each task. Exercises included repeated practice of tasks using optimised movement patterns. Verbal cues and visual aids were used to assist the patient. Based on patient performance, task difficulty was progressed by varying repetitions performed, increasing load or speed or changing support surface.

Standard rehabilitation (Standard) (online supplementary appendix B): treatment focus was on progressive lower extremity and trunk strengthening and lower extremity flexibility. Patient education included instruction to modify intensity, frequency or duration of patient-specific tasks. Strengthening and flexibility exercises prescribed were selected using current clinical practice guidelines17 and previous reports.5 18 Each patient was progressed by increasing repetitions performed or increasing load.

Primary outcomes: feasibility

Primary outcomes were related to feasibility of the larger trial. Recruitment rate was defined as the number of patients deemed eligible who agreed to participation. Retention rate was defined as the percentage of those who completed post-treatment testing. Patient treatment session adherence was defined as the percentage of supervised visits attended. Patient HEP adherence was defined as the percentage of days the patient reported completing their HEP.

To assess treatment fidelity,11 12 we assessed PT treatment delivery and patient treatment receipt. Treatment delivery was assessed using prestudy assessment and poststudy chart reviews to assess protocol adherence. Prestudy assessment included a written exam and role-played scenarios.19 For role-played scenarios, a checklist was used to document standard performance of active ingredients for each treatment. To assess protocol adherence, a PT who was not involved in providing treatment completed chart reviews. A standard form was used to identify if performance of active ingredients for each treatment arm was documented. Protocol adherence was scored as percentage of active ingredients completed.

In addition to our a prior feasibility outcomes, we assessed patient treatment receipt, which relates to ability to understand key treatment concepts, and ability to independently perform tasks.11 12 Using our previously published methods,19 treatment receipt was scored by the treating PT as the proportion of exercises the patient performed independently.

Secondary outcomes: preliminary effectiveness

Preliminary effectiveness outcomes determined a priori were the Hip dysfunction and Osteoarthritis Outcome Score (HOOS) subscales of activities of daily living (ADL) and symptoms,20 hip adduction angle during a single leg squat and hip muscle strength.

Kinematics

A digital camera was used to capture two-dimensional motion while the patient completed three single leg squats.27 figure 2 demonstrates the variables of interest including hip adduction, pelvic tilt (obliquity/drop) and trunk lean (ipsilateral lean). Values of three trials were averaged for each variable. Inter-rater reliability of all measures among our group was excellent (intraclass correlation (ICC_3,3:) >0.98, SE of measurements <1°).

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Figure 2

(A) Initial position. Line A is drawn between the anterior superior iliac spine (ASIS) markers and is the initial position of the pelvis. Line B is drawn from the sternal marker to the midpoint of line A and is the initial position of the trunk. (B) Final depth of squat. Line C is drawn between the ASIS markers and is the final position of the pelvis. Line D is drawn from the sternal marker to the midpoint of line C and is the final position of the trunk. Line E is drawn from the ASIS marker to the femur marker on the weight-bearing leg and is the final position of the femur. (C) Angle measurement. Hip adduction angle is defined by lines C and E. Positive values indicate hip adduction; pelvic excursion is defined by lines A and C. Negative values indicate a pelvic tilt in which the non-weight-bearing side is lowering; trunk excursion is defined by lines B and D. Positive values indicate the trunk is leaning towards the weightbearing limb.

A priori criteria for success

A priori criteria for success included: (1) 46 participants recruited; (2) 90% retention9; (3) 90% adherence to attending treatment sessions; (4) 80% adherence to HEP; and (5) treatment providers scoring at least 95% on prestudy examination and 80% protocol adherence.

We hypothesised MoveTrain would demonstrate greater improvement in HOOS and greater reduction in peak hip adduction during functional tasks compared with Standard, despite possibly demonstrating less hip strength.

Pilot trial sample size

Sample size for primary outcomes was based on precision and assumed that observed rates of adherence and retention would be at least 90%.9 With a sample size of 46 (23/group), 95% CI around observed rates of adherence and retention were expected to be 78%–96% (ie, within 9% of the true rate). The study was designed to estimate effect sizes for treatment outcomes; therefore, the study was 80% powered to detect large effect sizes of 0.9 or above.

Randomisation

Patients were randomised to treatment in 1:1 ratio stratified by site, sex and HOOSSymptoms subgroup (determined from median split of preliminary data). Within each stratum, patients were allocated using a variable block size. Randomisation sequences were generated a priori using a formal probability model and were elicited from the data capture system. Given the nature of treatment, it was not possible to blind treating PTs or patients to treatment assignment. Study personnel performing assessments and kinematic measurements were blinded to group.

Statistical analysis

Fisher’s exact test compared retention and patient adherence to treatment session rates by site and by group. Patient adherence to HEP, therapists’ treatment delivery and patient treatment receipt were compared by site and group using Wilcoxon’s test.

Data collected at pretest and post-test were analysed with analysis of covariance where post-test was the dependent variable, pretest was the covariate and treatment group was the independent variable that tests the null hypothesis that after adjusting for pretest, post-test is not significantly different across treatment groups. A general linear model was used when residuals were normally distributed, and homogeneity of regression lines assumption was satisfied, otherwise non-parametric covariance analysis30 was used. Multinomial generalised estimating equations was used to analyse ordinal pain numeric rating scales.

Primary outcomes: feasibility

Table 1 provides baseline characteristics of study groups. Overall results related to study feasibility along with site-specific and treatment group-specific comparisons are provided in table 2.

Secondary outcomes: preliminary effectiveness

Both groups demonstrated improvements in all HOOS subscales; however, there were no between-group differences (table 4). Both groups also demonstrated similar improvements in PSFS, PROMIS scores and Pain Numeric Rating scales. MoveTrain demonstrated a greater reduction in hip adduction and pelvic tilt (drop) during the single leg squat compared with Standard (table 5). Both groups demonstrated similar increases in strength after treatment ranging from 6% to 16% (table 5).

Feasibility

We were able to meet our recruitment goals within 13 months of initiating recruitment. This suggests our recruitment methods would result in an estimated 177 patients for a 5-year project. Our retention rate for post-treatment testing was 91%, higher than the 80% follow-up required for a high-quality RCT.31 We provided compensation for testing sessions and treatment free of charge, which may have increased retention. Additionally, there was frequent contact between study personnel and patients, including weekly treatment sessions and multiple communications with research coordinators.

Treatment session attendance was high, indicating feasibility of weekly supervised sessions. Patient self-reported HEP adherence was lower than hypothesised. Based on informal discussions and written communications, patients reported difficulty completing all exercises every day and suggested the HEP be modified. Despite lower than expected HEP adherence, patients in both groups demonstrated improvements in HOOS and treatment-targeted mechanism, kinematics and strength. Decreasing HEP frequency may result in similar treatment effects and assist in improving HEP adherence.

We have developed methods to establish and monitor treatment fidelity. In the future, we will use the checklist used for role-played scenarios to monitor actual treatment sessions. For chart reviews, we noted the two items most often scored as insufficient included ‘review of key concepts’ and ‘addressing barriers to HEP completion’. Discussion with treating PTs indicated they indeed performed these tasks; however, they did not specifically document their strategies. In the future, we will modify treating PTs’ documentation forms to provide a specific place to document these two key items. This addition will serve as an improved method to ensure documentation of protocol adherence and as a reminder to treating PTs to perform these items.

Preliminary effectiveness

Our study was designed to assess feasibility; therefore, we did not expect to find statistical differences in secondary outcome measures. Both groups demonstrated similar improvements in all patient-reported outcomes. These findings are important because it suggests that patients with HRGP may benefit from PT-led intervention. Patients in this study reported moderate activity limitations at baseline. After treatment, HOOS subscales were substantially improved with increases of 12–24 points. No unexpected adverse events occurred, suggesting these interventions are safe.

After treatment, MoveTrain did demonstrate a significantly larger reduction in hip adduction and pelvic drop during single leg squat compared with Standard, supporting our a priori hypothesis. The goal of MoveTrain training is to improve lower extremity kinematics during daily and patient-specific tasks. Because MoveTrain changes the way people move, stresses on joint tissues may be altered, potentially resulting in greater long-term effects than Standard. Interestingly, fewer patients in MoveTrain reported discomfort with their exercises (table 3). We are currently collecting patient-reported outcome measures 6 and 12 months after treatment to determine if between-group differences emerge over time. Further investigation is warranted to determine if the improved movement patterns can be sustained over time and have a protective influence on the hip.

There were similar strength improvements, ranging from 6% to 16%, in both patient groups. Although the MoveTrain group did not perform traditional strengthening exercises, the functional tasks performed MoveTrain incorporated general principles of strength training. Based on patient performance, the tasks were progressed by level of difficulty or by increasing resistance. Therefore, these progressive activities may have contributed to improved muscle strength.

Limitations

We cannot make definitive statements regarding efficacy of MoveTrain or Standard treatment; however, our results are promising. Improvements were reported in both treatment groups, and those in MoveTrain improved their kinematics. We did not have a control group; therefore, patient improvement may be related to passage of time. We consider this unlikely, because in our proof-of-concept study,9 patients with HRGP randomised to a 6-week waitlist demonstrated a worsening in HOOSADL and no improvement in other HOOS subscales compared with baseline. Additionally, our patients reported pain duration greater than 3 months prior to enrolling, suggesting that time alone may not explain our results. We must acknowledge that we have completed a number of statistical tests, therefore increasing the likelihood of a type I error. We identified our a priori variables of interest and focused our discussion on results related to these variables. However, given limited information related to non-operative management of HRGP, we believe it important to report all analyses that may be useful for future investigations. Finally, we did not establish test–retest reliability of the strength measures used in this pilot study; however, we will include reliability testing for the future trial.

We completed a pilot, multicentre RCT to assess our capability of completing a larger, definitive RCT to assess the efficacy of MoveTrain. We encountered no major problems and have determined a full study can proceed with modifications. Preliminary results from this study suggests that both MoveTrain and Standard may result in improved patient-reported outcomes; however, only MoveTrain resulted in improved lower extremity kinematics. Additionally, fewer patients reported discomfort with the exercises provided in MoveTrain, which may influence patient adherence to treatment. Further investigation of MoveTrain is warranted. We do not know if the improvements in patient-reported outcomes observed in this study were due to the treatment provided or due to the fact that the participants interacted with a healthcare professional. An adequately powered RCT is needed to assess the efficacy of MoveTrain compared with an attention control. Future work will also include the assessment of the sustained benefits of PT-led interventions.