June 6, 2023

Hip Strength and Hip and Knee Kinematics During Stair Descent in Females With and Without Patellofemoral Pain Syndrome

This article investigates the correlation between hip strength and kinematics during stair descent in females with and without patellofemoral pain syndrome.

Brent Brookbush

DPT, PT, MS, CPT, HMS, IMT

Research Review: Hip Strength and Hip and Knee Kinematics During Stair Descent in Females With and Without Patellofemoral Pain Syndrome

By Tristan Rodik, M.AT., ATC

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Bolgla, L. A., Malone, T. R., Umberger, B. R., and Uhl, T. L. (2008) Hip strength and hip and knee kinematics during stair descent in females with and without patellofemoral pain syndrome. Journal of Orthopaedic & Sports Physical Therapy, 38(1), 12-18 ABSTRACT

Why the Study is Relevant: Patellofemoral pain syndrome (PFPS) is a common complaint among healthy, active females. Current research highlights the importance of hip strength in PFPS patients (1-8). This 2008 study compared hip strength and hip and knee kinematics in women with and without PFPS. The findings suggest that PFPS result in weaker hip external rotators and hip abductors with no significant difference in hip or knee kinematics. This suggests that human movement professionals should assess and address hip strength when treating females with PFPS, even when changes to kinematics are not obvious.

Caption: Dr. Brent Brookbush tests the Gluteus Medius using a Manual Muscle Test modified for an active population

Gluteus Medius Manual Muscle Testing

Study Summary

Study Design	Cross-sectional, observational cohort
Level of Evidence	Level III Evidence from non-experimental, comparative study
Subject Characteristics	Experimental Group Demographics: Age (in years): 24.5 + 3.2 Gender: female Number of Participants: 18 Height: 1.7 + 0.1m Body Mass: 63.1 + 9.1kg Duration of Symptoms: 14.4 + 12.8 months Inclusion Criteria: Anterior knee pain during stair descent Pain for at least one month Pain during at least two of the following: Stair ascent Squatting Kneeling Prolonged sitting Exclusion Criteria: Previous knee surgery or significant knee injury Traumatic patellar dislocations Neurological involvement that would affect gait Previous hip surgery or significant injury Control Group Demographics: Age (in years): 23.9 + 2.8 years Gender: female Number of Participants: 18 Height: 1.7 + 0.1m Body Mass: 62.1 + 8.5kg Inclusion Criteria: No history or diagnosis of knee pathology No pain with any of the following: Stair ascent Squatting Kneeling Prolonged sitting No history of hip pathology
Methodology	Participants with PFPS rated their pain over the previous week using the 10-cm visual analog scale (VAS) Anthropometric measurements for each participant were taken The most affected lower extremity was tested for the PFPS group Isometric strength testing was measured via a handheld dynamometer to assess hip abductor and external rotator strength Participants provided a maximum voluntary isometric contraction A stair climbing task was used for kinematic testing
Data Collection and Analysis	Isometric testing was conducted with a Commander Power-Track II (J Tech Medical, Salt Lake City, UT) handheld dynamometer Video data was recorded using a seven-camera motion capture (Motion Analysis Corporation, Santa Rosa, CA) Knee frontal plane, hip transverse and frontal plane angles were calculated using OrthoTrak 5.0 software (Motion Analysis Corporation) Independent t-tests were used to evaluate differences for age, height and body mass Intraclass correlation coefficients were used to determine reliability P-value for strength and kinematic values were adjusted to 0.025 and 0.017, respectively
Results:	Pain assessment for the PFPS group was 4.4 + 1.5 cm on the VAS Participants between groups were similar in age, height and body mass (p > 0.44) PFPS participants had significantly lower hip external rotator (p = 0.002) and hip abductor strength (p = 0.006) when compared to the control group PFPS participants had 24% and 26% less hip external rotator and hip abductor strength compared to the control group, respectively Similar results were noted between the PFPS and control groups for hip internal rotation (2.1° to 1.0°, p = 0.67) and hip abduction (1.0° to 2.6°, p = 0.15) measures during the stair descent, respectively Knee varus was also similar between the PFPS and control group (5.7 to 2.9, p = 0.28), respectively
Our Conclusions	The findings suggest that assessing hip external rotator and hip abductor strength should be part of the evaluation process in females presenting with PFPS. This study did not find a relationship among PFPS and hip or knee kinematics but the task performed (stair climbing) may not have been demanding enough to elicit kinematic changes.
Researchers' Conclusions	The findings are in accordance with prior literature demonstrating decreased hip abductor and external rotator srength in females with PFPS (2-4). No significant differences among groups were demonstrated in knee valgus angles, hip adduction, or hip internal rotation during stair descent.

Review and Commentary

This study adds to a growing body of research revealing hip abductor and external rotator weakness in females with patellofemoral pain syndrome (PFPS) (3, 5-7). However, no significant differences between the experimental and control groups were observed in hip and knee kinematics during the stair descent task. This may imply that a decrease in hip abductor and external rotator strength/activity is sufficient to result in a pain syndrome without gross change in kinematics. Alternatively, this could imply that the stair decent task was not a sufficient challenge to highlight changes in kinematics in this young, healthy population.

This study had the following methodological strengths:

The reliability of the hip and knee kinematics testing was evaluated by re-testing seven participants 5-7 days after the initial session.
The assessments used were similar to those commonly used in a clinical setting - stair climbing and manual muscle testing (9).
Hip and knee kinematics along with hip strength were evaluated within the same cohort. This is important as the study evaluated kinematics in patients who had hip abductor and hip external rotator weakness along with PFPS.

Weaknesses to note prior to clinical integration:

Pain was not assessed during stair descent.
Examiners were not blinded which could bias assessment.
The stair descent task may not have been demanding enough to elicit altered lower-extremity kinematics. Research has demonstrated significant changes in hip kinematic during running when comparing PFPS participants to pain free controls (8).
The right lower extremity was the only extremity tested for the control group while the tested extremity for the PFPS group involved the more symptomatic side. Future research should assess an equal side of left and right limbs for appropriate comparison.

Why This Study is Important:

This study provides evidence in establishing a relationship between PFPS and hip strength, but not between PFPS and hip or knee kinematics. This may imply that a decrease in hip abductor and external rotator strength/activity is sufficient to result in a pain syndrome without gross change in kinematics. Alternatively, this could imply that the stair decent task was not a sufficient challenge to highlight changes. Last it could be that the changes in kinematics were too small to be reliably detected by the motion analysis system, for example, arthrokinematics may have been altered without gross change in osteokinematics.

How the Findings Apply to Practice:

This study suggests that hip external rotator and abductor strength is assessed and addressed in individuals exhibiting symptoms of PFPS, even when gross alterations in kinematics are not noted. This study may also suggest that kinematic assessment is done using a more demanding task then stair decent, for example, running may be better suited for a young, healthy population presenting with PFPS to assess movement impairments (5, 8).

How Does This Study Relate to Brookbush Institute Content?

The Brookbush Institute (BI) uses an integrated approach to address postural dysfunction and movement impairments. In this study, patients presenting with PFPS had significant weakness in hip external rotators and abductors, congruent with the predictive models of Lower Extremity Dysfunction (LED) and Lumbo Pelvic Hip Complex Dysfunction (LPHCD) , (specifically the predictions of gluteus medius and gluteus maximus inhibition). The Brookbush Institute (BI) uses the Overhead Squat Assessment (OHSA) for kinematic assessment and manual muscle testing to determine specific muscle weaknesses, for example glutues medius /maximus weakness. The BI model emphasizes the importance of hip strengthening, from isolated activation to reactive activation to subsystem integration .

Hip Strength and Hip and Knee Kinematics During Stair Descent in Females With and Without Patellofemoral Pain Syndrome

Research Review: Hip Strength and Hip and Knee Kinematics During Stair Descent in Females With and Without Patellofemoral Pain Syndrome

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