Abstract
The purpose of this study was to compare the preliminary effects of movement pattern training (MoveTrain) versus strengthening/flexibility (standard) treatment on hip and pelvic biomechanics in patients with chronic hip-related groin pain. This is a secondary analysis of data collected during a pilot randomized clinical trial. Thirty patients with hip pain, between the ages of 15 and 40 years, were randomized to MoveTrain or standard. Both groups completed 10 treatment sessions over 12 weeks along with a daily home exercise program. Three-dimensional motion analysis was used to collect kinematic and kinetic data of the pelvis and hip during a single-leg squat task at pretreatment and immediately posttreatment. Compared with the standard group, the MoveTrain group demonstrated smaller hip adduction angles (P = .006) and smaller hip external adduction moments (P = .008) at posttreatment. The desired changes to hip joint biomechanics, as found in this study, may require specificity in training that could allow health care professionals to better customize the rehabilitation of patients with hip pain. These findings can also be applied to the design and implementation of future clinical trials to strengthen our understanding of the long-term implications of different rehabilitation techniques for patients with hip pain.
Keywords: hip joint, rehabilitation, femoroacetabular impingement, movement system
Chronic hip-related groin pain, hereafter hip pain, is defined as groin pain originating from the hip joint1 that has been present >3 months and can be caused by hip disorders such as femoroacetabular impingement syndrome, acetabular dysplasia, labral tears, and injury to other intra-articular structures.2,3 This type of hip pain significantly limits activity among young to middle-aged adults. Left untreated, the underlying biomechanics that cause this pain may contribute to early development of hip osteoarthritis.4–6 However, the effects of different treatments, such as movement pattern training and standard rehabilitation, on hip and pelvis kinematics and kinetics are unclear, and further research is needed to better match patients to optimal treatments.
Bony morphologies are associated with tissue pathology7; however, other factors may also contribute to a patient’s pain. Repeated altered loading of the hip joint with abnormal movement patterns, such as excessive hip adduction, may contribute to cumulative tissue stress and subsequent hip pain.8–11 Previous studies have shown that lower-extremity movement patterns impact the mechanical loading at the hip joint.12,13 The movement system impairment theory8,14 suggests that altered loading, due to abnormal movement patterns, may contribute to cumulative microtrauma through altered joint tissue stresses and irritation, potentially leading to the presentation of musculoskeletal pain syndromes, such as hip pain. Rehabilitation strategies to improve lower-extremity movement patterns may result in decreasing stresses on the hip joint structures and, thus, reduce pain experienced by the patient. Previous studies have demonstrated that abnormal lower-extremity movement patterns are modifiable with specific training to change the movement pattern; however, these movement patterns may not be modifiable with strengthening alone.15–19
The goal of movement pattern training (MoveTrain) is to reduce loading on the hip joint by optimizing hip joint motion during functional tasks. Previous analysis from our lab found that after participation in MoveTrain, patients who displayed a greater reduction in hip adduction angle had a greater improvement in hipspecific reports of pain and function, quantified using the modified Harris Hip Score.17 Thus, there is evidence that correcting abnormal movement patterns can improve function and reduce pain. However, the effect of MoveTrain on hip joint moments remains poorly understood. In particular, kinetic profiling of rehabilitation interventions for hip pain is sparse. Data regarding hip joint moments are important as they provide an additional layer of understanding of biomechanical changes over the course of treatment. With reduced hip adduction motion, it is reasonable to assume that external hip adduction moments would be reduced as well. Although it is possible that larger hip adduction moments could be used to strengthen hip abductors, it could result in increased joint loads. In addition, our previous analysis found that muscle strength was not directly associated with significant improvement in pain and function.17 A better understanding of the relationships between hip moments during specific movement tasks and patient outcomes would be useful in assessing treatment effects and optimizing future rehabilitation treatments. As such, the goal of this study is to be hypothesis generating. We hope our work will contribute to future studies aimed at advancing our understanding of biomechanical outcomes of rehabilitation treatments.
The primary aim of our analysis was to compare joint kinematics and kinetics at the hip joint during a single-leg squat between patients who received MoveTrain versus standard strengthening and flexibility (standard) treatment. We previously completed a pilot randomized clinical trial (RCT; ClinicalTrials.gov #NCT02913222) comparing MoveTrain with a (standard) treatment for people with chronic hip-related groin pain.15 Results from this parent study established feasibility of completing a larger, multicenter RCT to compare effectiveness of MoveTrain with standard treatment. In addition, both groups demonstrated clinically important improvements in function and muscle strength. In this secondary study, we used three-dimensional (3D) motion analysis to compare hip and pelvic angles as well as hip joint moments during a single-leg squat between patients with hip pain who received MoveTrain versus standard treatment. We hypothesized that compared with patients who received standard treatment, patients who received MoveTrain would demonstrate smaller hip adduction angles and smaller hip external adduction moments after treatment completion.
Methods
Participants
Study participants consisted of a consecutive sample of patients who were recruited between January 2017 and February 2018 from community clinics, research volunteer databases, social media, and flyers. To be eligible, patients had to (1) be between 15 and 40 years old; (2) report deep hip joint or anterior groin pain that was reproducible with flexion, adduction, internal rotation test20,21; (3) report pain ≥3/10 for at least 3 months; and (4) demonstrate functional limitation with modified Harris Hip Score22 <90. Exclusion criteria included: (1) previous hip surgery, fracture, infection, or pain due to high-impact trauma; (2) diagnosis of Legg–Calve–Perthes Disease, slipped capital femoral epiphysis, or inflammatory disease; (3) neurological involvement affecting balance; (4) radiating numbness, pain, or tingling into thigh; (5) pregnancy; and (6) referred pain from spine as indicated by screening tests.
Study Design
We performed a secondary analysis of data from a pilot multicenter RCT comparing MoveTrain and standard therapy for patients with hip pain.15 The original study was designed with 46 participants to assess the viability of performing a larger, multicenter RCT and compare the preliminary effects of these 2 treatments. The primary findings of the original study have been reported.15 Additional funding allowed for 3D motion analysis of participants enrolled at the Washington University in St. Louis site only (n = 30, 70% of the original study group). The sample size used for these analyses provided 80% statistical power to detect very large effect sizes of 1.1 or greater. This study was approved by the Human Research Protection Office of Washington University in St. Louis. All patients provided written informed consent prior to participating.
Assessments (Pretreatment and Posttreatment)
Participants who passed initial screening underwent pretreatment assessments, which included completion of self-report questionnaires and 3D motion analysis of lower-extremity movement patterns. If a patient reported bilateral pain, the most bothersome hip was the test limb. After the completion of pretreatment testing, the study participants were randomized into either the MoveTrain or the standard treatment group.15 Patients were stratified by sex and Hip Disability and Osteoarthritis Outcome Score Symptoms subscale and allocated using a variable block size. Upon completion of treatment sessions, participants completed posttreatment assessments, which mirrored the previous pretreatment assessments.
Predictor Variables—Interventions
Treatments for both groups included 10 physical therapist-supervised sessions over 12 weeks and instruction in a daily home exercise program. The MoveTrain intervention arm focused on task-specific training during which each patient was taught to reduce excessive hip joint motions displayed, most commonly excessive hip adduction and internal rotation, while performing daily (walking and stair climbing) and patient-specific (work and fitness activities) tasks. Descriptions of these identifying abnormal movements are provided in a previous publication.15 One of the practiced tasks included a single-leg squat, which was the task evaluated in this study. The standard treatment intervention arm focused on progressive lower extremity and trunk strengthening and lower-extremity flexibility. Specific exercises for the standard group were selected from current clinical practice guidelines.23–25 Single-leg squat was not included in the standard treatment protocol. Detailed descriptions of interventions provided within both treatment arms have been previously published.15 Patients and treating physical therapists were not able to be blinded to treatment assignment, but all personnel performing assessments, data collection, processing, and analysis were blinded to treatment group.
Outcome Variables
3D kinematic data for each patient were recorded at 100 Hz using a 10-camera, video-based motion capture system (Vicon Nexus, Oxford metrics) while the participants performed single-leg squats at their self-selected speed. For kinetic data, ground reaction forces were collected at 2000 Hz using 2 in-ground, 40 cm × 60 cm force platforms (Bertec). Seventy-two skin-mounted retroreflective markers were placed on anatomical landmarks of the trunk, pelvis, and lower extremities, and rigid 4-marker clusters for tracking were placed at the thigh and lower leg. Marker trajectory and ground reaction force data were low-pass filtered with 6-Hz cut-off frequencies. Joint angles (hip flexion, hip adduction, pelvic tilt, and pelvic obliquity) as well as external hip joint moments (flexion and adduction) were evaluated at the point of maximum descent during the single-leg squat. The maximum descent was determined to be the instant when the participant’s center of mass velocity reached 0 along the vertical axis, indicating the change of direction at the maximum depth of the squat. Although squat depth was not forcefully restricted, visual appraisal and verbal cuing were used to attempt to have participants squat similar depths. Three repetitions of the single-leg squat were collected and averaged for each variable. Visual3D software (C-motion, Inc) was used to calculate joint angles and external moments normalized to body mass.26,27 A 6 degrees of freedom model was used for the pelvis and hip joint. A Harrington equation to calculate hip joint center was used.28 Pelvic angles were defined relative to the lab coordinate system, and hip angles were defined as femur relative to the pelvis. We have provided additional information about data collection and processing in Supplementary Material S1 (available online). We previously established our test–retest reliability for hip joint angles by assessing the same participants during 2 testing sessions with 1 to 2 weeks between sessions: Our reliability was excellent for hip flexion (intraclass correlation coefficient [ICC]3,3 = .90, standard error of the mean [SEM] = 4.1°, MDC95 = 11.4°) and moderate for hip adduction (ICC3,3 = .88, SEM = 1.4°, MDC95 = 3.9°), pelvic tilt (ICC3,3 = .85, SEM = 2.9°, MDC95 = 8.0°), and pelvic obliquity (ICC3,3 = .87, SEM = 1.4°, MDC95 = 3.9°).29,30
Statistical Analysis
Pre- and posttreatment data were analyzed with analysis of covariance such that posttreatment was the dependent variable and pretreatment was the covariate. Treatment group was the independent variable that tested the null hypothesis that after adjusting for pretreatment, posttreatment is not significantly different across treatment groups. Analysis of covariance can be considered analogous to mathematically adjusting the posttreatment mean of the 2 treatment groups to what they would have been if both groups had started out at the same pretreatment value. When residuals were normally distributed and the homogeneity of regression lines assumption was satisfied, a generalized linear model was used for the statistical analyses. When residuals were not normally distributed, nonparametric analysis of covariance was used.31 All P values are 2-sided and interpreted as statistically significant when <.05. To evaluate clinical relevancy, the minimal detectable change (MDC) for each of the kinematic variables was calculated and reported.30
Results
Table 1 provides demographic data for all patients included in this analysis who provided posttreatment data. Upon review of group kinematic and kinetic data, it was determined that the values of 1 participant randomized into the standard group were statistical outliers. Upon assessment of the data collection videos, we determined that their movement was not representative of the instructed task and chose to exclude that participant’s data. Full data were available for 29 participants, 16 in MoveTrain and 13 in standard. Both treatment groups demonstrated improvements in all self-reported Hip Disability and Osteoarthritis Outcome Score subscales. Consistent with the parent study,15 posttreatment values in this subsample for all Hip Disability and Osteoarthritis Outcome Score subscales were not significantly different by treatment group (Table 2).
Table 1.
Demographics for All Patients Providing Posttreatment Data
| Variable | All (N = 29) | Patients by treatment group |
|
|---|---|---|---|
| MoveTrain (n = 16) | Standard (n = 13) | ||
|
| |||
| Age (y), mean (SD) (range) | 28.3 (5.1) (22–29) | 27.8 (1.2) (22–37) | 28.9 (1.5) (22–39) |
| Gender, n, % | |||
| Male | 11 (37.9%) | 7 (43.8%) | 4 (30.8%) |
| Female | 18 (62.1%) | 9 (56.3%) | 9 (69.2%) |
| Study limb, n, % | |||
| Left | 13 (44.8%) | 10 (62.5%) | 6 (46.2%) |
| Right | 16 (55.2%) | 6 (37.5%) | 7 (53.8%) |
| Bilateral pain, n, % | |||
| No | 19 (65.5%) | 12 (75.0%) | 7 (53.8%) |
| Yes | 10 (34.5%) | 4 (25.0%) | 6 (46.2%) |
| Measured body mass index (kg/m2), mean (SD) (range) | 25.0 (5.9) (19.4–46.1) | 24.8 (1.3) (19.4–40.6) | 25.3 (1.9) (20.2–46.1) |
Table 2.
Summary of Results of Patient-Reported Outcomes
| Variable | Pretreatment, mean (SD) | Posttreatment, mean (SD) | Within-group change,* mean (SD) | Adjusted immediate treatment effect,§ mean (95% CI) | Adjusted immediate treatment effect, P† |
|---|---|---|---|---|---|
|
| |||||
| HOOSPain** | |||||
| MoveTrain, n = 16 | 72.2 (11.7) | 88.3 (10.1) | 16.1 (8.4) | −2.80 (−7.87 to 2.26) | .27 |
| Standard, n = 13 | 74.2 (8.7) | 92.1 (5.3) | 17.9 (8.1) | ||
| HOOSSymptoms** | |||||
| MoveTrain, n = 16 | 66.9 (16.0) | 81.6 (13.6) | 14.7 (11.6) | 0.15 (−8.55 to 8.86) | .97 |
| Standard, n = 13 | 72.7 (11.7) | 85.0 (14.4) | 12.3 (12.8) | ||
| HOOSADL** | |||||
| MoveTrain, n = 16 | 85.3 (11.0) | 95.8 (6.3) | 10.5 (11.0) | −1.45 (−5.01 to 2.11) | .43§§ |
| Standard, n = 13 | 89.4 (7.2) | 97.7 (2.6) | 8.4 (8.0) | ||
| HOOSSport** | |||||
| MoveTrain, n = 16 | 64.5 (18.6) | 85.5 (13.8) | 21.1 (14.9) | −5.37 (−12.82 to 2.08) | .16§§ |
| Standard, n = 13 | 71.6 (15.2) | 93.3 (6.5) | 21.6 (16.7) | ||
| HOOSQOL** | |||||
| MoveTrain, n = 16 | 58.6 (14.2) | 73.4 (16.4) | 14.8 (13.1) | −6.89 (−15.96 to 2.18) | .14§§ |
| Standard, n = 13 | 52.9 (11.6) | 77.4 (11.0) | 24.5 (13.6) | ||
Abbreviations: CI, confidence interval; HOOS, Hip Disability and Osteoarthritis Outcome Score; HOOSADL, function in activities of daily living; HOOSQOL, quality of life; HOOSSport, function in sports and recreation.
Change is calculated by subtracting the pretreatment value from the posttreatment value.
The adjusted treatment effect from least squares means is calculated by subtracting the standard group from the MoveTrain group at posttreatment and assesses the between-group difference in posttreatment values after adjusting for pretreatment.
Unless otherwise indicated, P value by analysis of covariance using a generalized linear model.
Patient-reported outcome measures with 100 = no disability.
P value by nonparametric analysis of covariance.
After adjusting for pretreatment values, posttreatment hip flexion angle, pelvic sagittal tilt angle, and pelvic obliquity angle were not significantly different between treatment groups (Table 3). After adjusting for pretreatment hip adduction angle, posttreatment hip adduction angle was significantly less for patients in the MoveTrain group compared with those in the standard treatment group (P = .006; Figure 1).
Table 3.
Summary of Results for Kinetic and Kinematic Variables for the Study Test Limb
| Variable | Pretreatment, mean (SD) | Posttreatment, mean (SD) | Within-group change,* mean (SD) | Adjusted immediate treatment effect,§ mean (95% CI) | Adjusted immediate treatment effect, P† |
|---|---|---|---|---|---|
|
| |||||
| Kinematics,° | |||||
| Hip flexion angle | |||||
| MoveTrain, n = 16 | 81.4 (13.3) | 80.9 (13.7) | −0.49 (16.2) | −0.34 (−9.51 to 8.83) | .94 |
| Standard, n = 13 | 78.4 (13.4) | 79.7 (13.4) | 1.29 (8.0) | ||
| Hip adduction angle | |||||
| MoveTrain, n = 16 | 13.5 (6.7) | 8.7 (6.6) | −4.79 (6.9) | −6.25 (−10.54 to – 1.96) | .006 |
| Standard, n = 13 | 13.3 (5.4) | 14.8 (7.1) | 1.52 (4.3) | ||
| Pelvic tilt angle,** | |||||
| MoveTrain, n = 16 | 37.0 (9.9) | 39.0 (8.9) | 2.00 (10.6) | 3.39 (−2.23 to 9.01) | .23 |
| Standard, n = 13 | 35.7 (9.3) | 35.1 (7.4) | −0.68 (6.7) | ||
| Pelvic obliquity angle,‡ | |||||
| MoveTrain, n = 16 | −4.7 (5.9) | −1.2 (5.8) | 3.54 (6.6) | 2.91 (−0.93 to 6.76) | .13 |
| Standard, n = 13 | −4.5 (6.5) | −4.0 (6.1) | 0.52 (4.2) | ||
| Kinetics, N⋅m/kg | |||||
| Hip flexion moment | |||||
| MoveTrain, n = 16 | 1.3 (0.3) | 1.3 (0.4) | 0.07 (0.4) | −0.002 (−0.25 to 0.25) | .99 |
| Standard, n = 13 | 1.2 (0.3) | 1.3 (0.4) | 0.08 (0.2) | ||
| Hip adduction moment | |||||
| MoveTrain, n = 16 | 0.8 (0.2) | 0.8 (0.2) | −0.06 (0.1) | −0.17 (−0.27 to – 0.08) | <.001 |
| Standard, n = 13 | 0.9 (0.2) | 1.0 (0.2) | 0.10 (0.1) | ||
Abbreviation: CI, confidence interval.
Change is calculated by subtracting the pretreatment value from the posttreatment value.
The adjusted treatment effect from least squares mean is calculated by subtracting standard from MoveTrain at posttreatment and assesses the between-group difference in posttreatment values after adjusting for pretreatment.
Positive pelvic tilt values correspond to an anterior pelvic tilt.
Pelvic obliquity: a negative value indicates a contralateral pelvic drop.
P value by analysis of covariance using a generalized linear model.
Bolded values indicate statistical significance (P < .05).
Figure 1 —
Hip adduction angles pre- and posttreatment. Data reflect the raw data mean at each visit. Error bars represent the SD. *Statistically significant difference (P = .006).
After adjusting for pretreatment values, posttreatment hip flexion moment was not significantly different between treatment groups (Table 3). After adjusting for pretreatment hip adduction moment, posttreatment hip adduction moment was significantly less for patients in the MoveTrain group compared with those in the standard treatment group (P < .001; Figure 2).
Figure 2 —
Hip adduction moments pre- and posttreatment. Data reflect the raw data mean at each visit. Error bars represent the SD. *Statistically significant difference (P < .001).
Discussion
Our analysis revealed posttreatment hip kinematic and kinetic differences among patients with chronic hip-related groin pain who completed movement pattern training or a standard program of lower extremity and trunk strengthening and lower-extremity flexibility. After treatment, the MoveTrain group demonstrated a significantly smaller hip adduction angle and hip external adduction moment during the single-leg squat compared with the standard group. These preliminary data suggest that changes to hip joint motion and hip joint loading may require specificity in training. Similar to those reported in the parent study,15 patient-reported measures of pain, symptoms, activity limitations, and quality of life were improved after treatment, suggesting that patients with hip pain may benefit from either treatment. Whether or not improvements in patient-reported outcomes are related to the kinematic or kinetic changes cannot be definitively determined from this study due to the small sample. A study with a larger sample may provide greater insight into these relationships. The long-term implications of the treatment differences in kinematic or kinetic changes would also be worth further investigation.
Kinematics
In this analysis, we investigated hip and pelvic motions using 3D motion analysis. Posttreatment, the MoveTrain group demonstrated a significantly smaller hip adduction angle during the single-leg squat compared with the standard group, thus supporting our hypothesis. In contrast, there were no between-group differences for hip flexion angle, pelvic flexion angle, or pelvic contralateral drop angle. Given the significant between-group difference in hip adduction motion, but not in pelvic contralateral drop, it is likely that femoral adduction may also be contributing to the differences in hip adduction. A reported change greater than the calculated MDC establishes that the change was not a result of random variation or measurement error at the 95% confidence level. Of the kinematic variables analyzed in this study, the only clinically relevant change was with hip adduction. The within-group change for hip adduction angle in the MoveTrain group was 4.79°, which is greater than the MDC95 of 3.9°. The within-group changes for hip adduction in the standard group and hip flexion, pelvic tilt, and pelvic obliquity for both groups were not clinically relevant changes. These findings are important because they suggest that movement patterns of the lower extremity may be changed by practicing specific tasks, such as the single-leg squat, while incorporating the movement pattern modifications. Progressive resistive exercises provided in the standard group did not result in movement pattern changes. Our current findings are in alignment with our previous work15–17 and other previous studies18,19 focusing on the knee joint that have reported changing movement patterns with specific task training. The inclusion of the single-leg squat as a practiced task for MoveTrain participants but not for standard participants likely explains these findings. Given that patients in both groups reported improvements in their hip-specific function, we cannot conclude that one treatment is superior to the other. We did not limit our study to only those patients who displayed excessive hip adduction. It is possible that those with excessive hip adduction may respond differently to MoveTrain or standard.
Kinetics
We hypothesized that the patients in the MoveTrain group would also demonstrate a smaller posttreatment hip external adduction moment during the single-leg squat compared with those in the standard group. Although our findings support this hypothesis, it is important to note that both groups reported similar symptom and pain reduction after treatment. Thus, it is unlikely that pain reduction explains the between-group differences noted. On average, the MoveTrain group decreased their hip adduction moment by 0.06 N·m/kg, whereas the standard group increased by 0.10 N·m/kg.
We do not know whether the between-group differences in posttreatment hip external adduction moment are clinically mean-ingful. Lower-extremity movement patterns have a direct influence on the mechanical loading at the hip joint.12 In a previous modeling study specific to patients with hip dysplasia, a 10° decrease in hip adduction angle during a single-leg squat task reduced resultant joint reaction forces at the hip joint, which may be beneficial for patients with hip pain.32 The posttreatment reduction in hip adduction angle in the MoveTrain group was smaller (<5°) than that modeled in the previous study; therefore, we do not know whether this change is sufficient. To our knowledge, the benchmarks for clinically important changes in kinetic outcomes have not been established in young adults with hip pain. Furthermore, it is unknown what type of change is desired. For example, it may be desired that the painful joint is unloaded at times when protection of the joint structures is needed to facilitate healing and then gradually rehabilitated to sustain a similar loading profile of the nonpainful joint. On the other hand, during rehabilitation, larger joint moments may be desired to strengthen muscle groups that oppose those moments. Ultimately, preventing harmful changes by stabilizing hip joint loading may have long-term benefits by reducing the progression of joint disease. Further investigation of these treatment protocols, in terms of the long-term effects and structural impacts on the hip joint, can improve our understanding of these rehabilitation mechanisms.
No studies have reported the effect of nonsurgical treatment on hip joint moments, and the few that have compared hip joint moments in patients with and without pain report conflicting results. Malloy et al33 investigated the single-leg squat task and reported smaller hip adduction moments among patients with femoroacetabular impingement syndrome compared with those without symptoms. Cvetanovich et al34 reported larger hip adduction moments among patients with femoroacetabular impingement syndrome compared with those without symptoms during a double leg squat; however, hip adduction moments were similar between groups during walking. They also investigated changes in hip adduction moment before and 6 months after arthroscopic surgery. After surgery, the patients demonstrated a nonsignificant (P = .06) decrease in peak hip adduction moment during a bilateral squatting technique but no change in peak hip adduction moment during walking.34 Given the differences in tasks investigated in the patient populations, it is difficult to make direct comparisons among the previous studies and ours. It is also difficult to determine whether larger or smaller moments are desired during rehabilitation.
Limitations
Although our results are promising, we cannot make definitive statements comparing the efficacy of MoveTrain versus standard treatment. This study is a secondary analysis of a pilot clinical trial; therefore, the patient sample is small. Given our small sample size, we limited our investigation to a small set of variables for which we had a priori hypotheses. Based on our clinical experience, we chose to analyze the kinematic and kinetic variable of interest at 1 time point, the deepest part of the squat. In Supplementary Material S2 (available online), we have provided time series graphs for the reported hip and pelvic kinematics and hip kinetics. These supplemental figures qualitatively demonstrate that the differences analyzed at maximum squat depth, which occurs at approximately 50% of the squat cycle, are representative of the differences across the entire squat cycle (Figures S1–S3 in the Supplementary Material S2 [available online]). Using a different approach, such as statistical parametric mapping, may provide additional insight. Because we were interested in patients’ preferred method, we did not standardize the squat depth. We, therefore, completed a post hoc analysis and determined that there were no differences in hip flexion, knee flexion, or ankle dorsiflexion at baseline (P < .46) or posttreatment (P < .19; Table S1 in the Supplementary Material S2 [available online]). Kinematics and kinetics of the adjacent joints and subgrouping based on underlying bony morphology should be considered with a larger sample.
Contralateral hip status was not controlled for in our analysis. When patients reported bilateral hip pain, the most bothersome side was evaluated as the test limb. As such, it is unknown what impact bilateral hip pain may have on these outcomes. Also, our analysis may not have been powered to detect differences among all variables assessed. As such, we present comparisons with confidence intervals to reflect the precision of the findings. Moreover, the results of several statistical tests are provided. We have not adjusted the P values for multiple comparisons due to the secondary nature of this analysis to be hypothesis generating rather than hypothesis confirming. In addition, MDCs were not calculated for kinetic outcomes as test–retest reliability data were not available.
Targeted interventions such as movement pattern training or a standard program of strength and flexibility training may be effective rehabilitation treatments for young adult patients with hip pain. This study concluded that compared with the standard treatment group, the MoveTrain group demonstrated smaller hip adduction angles and moments posttreatment. Ultimately, these findings will contribute to the development and optimization of treatment and improve our ability to better match patients to treatment.
Supplementary Material
Acknowledgments
The authors would like to acknowledge Megan Burgess, Visnja King, Suzanne Kuebler, Joseph Mancino, and Dave Wortman for providing treatment during the trial and Allyn Bove, Kathy Brown, Martha Hessler, and Darrah Snozek for their assistance with trial procedures and data collection.
Funding:
This work was supported by the following grants: the Orthopaedic Research Grant for the Foundation for Physical Therapy Research; R21HD086644 and NIH T32HD007434 from the National Center for Medical Rehabilitation Research, National Institute of Child Health and Human Development; and Washington University Institute of Clinical and Translational Sciences grant UL1TR002345 from the National Center for Advancing Translational Sciences (NCATS) of the National Institutes of Health (NIH). Additional support was provided by Program in Physical Therapy at Washington University School of Medicine, Clinical and Translational Science Award (CTSA) Grant [UL1 TR000448] and Siteman Comprehensive Cancer Center and National Cancer Institute Cancer Center Support Grant P30 CA091842.
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