Award Date

5-15-2026

Degree Type

Doctoral Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Committee Member

Daniel Young

Second Committee Member

Kai-Yu Ho

Number of Pages

40

Abstract

Purpose/Hypothesis: Single-limb dynamic weight-bearing tasks are frequently used to evaluate lower extremity and trunk movement patterns in individuals with patellofemoral pain (PFP). These individuals frequently exhibit abnormal frontal plane projection angles (FPPAs) at the trunk, pelvis, and lower extremities, indicative of altered movement patterns such as knee valgus, pelvic drop, and lateral trunk lean. While test-retest reliability and minimal detectable change (MDC) values for various FPPAs have been established in pain-free individuals, comprehensive data for individuals with PFP remain limited. Therefore, the purpose of this study was to evaluate test-retest reliability, as well as the standard error of measurement (SEM) and MDC, for multiple frontal plane kinematic variables at the trunk and lower extremities in individuals with PFP. We hypothesized that individuals with PFP would demonstrate differences in reliability metrics—reflected in intraclass correlation coefficients (ICC), SEM, and MDC values—when compared to previously reported values in pain-free populations.

Number of subjects: Ten individuals with PFP (6 males/4 females, age=28.2±6.9 yrs, BMI = 26.8 ± 6.7 kg/m2) participated.

Materials and methods: Participants completed two testing sessions separated by a minimum of 14 days. During each session, participants performed five functional tasks—single-leg squat, single-leg landing, single-leg hop, forward step-down, and lateral step-down—each for three repetitions on the symptomatic leg, with frontal plane video recording. Kinematics were measured for each task, encompassing trunk lean angle, hip FPPA, knee FPPA, and dynamic valgus index at peak knee flexion. Test-retest reliability between sessions was assessed using the ICC, model 3,k. The SEM for each frontal plane kinematic variable was calculated as the standard deviation multiplied by √(1 – ICC). The MDC was then determined using the formula: SEM × 1.96 × √2.

Results: While knee FPPA during the single-leg squat and hip FPPA during the single-leg landing fell within ranges reported for pain-free individuals, participants with PFP generally exhibited higher SEM and MDC values for hip, knee, and/or trunk FPPAs across the single-leg squat, single-leg landing, and lateral step-down tasks. Notably, increased SEM and MDC values were observed for hip FPPA, knee FPPA, and lateral trunk lean during the lateral step-down; for knee FPPA during the single-leg landing; and for hip FPPA and lateral trunk lean during the single-leg squat. Additionally, to our knowledge, this is the first study to report ICCs, SEMs, and MDCs for the dynamic valgus index in individuals with PFP.

Conclusions: Our findings highlight the importance of using pathology-specific reliability and MDC thresholds in clinical assessments. Individuals with PFP may require larger changes in movement patterns to reflect meaningful improvement relative to those without PFP.

Clinical relevance: Standard thresholds derived from pain-free populations may underestimate the degree of change needed to reflect true functional improvement in persons with PFP. Specific assessment criteria to the PFP population can enhance the accuracy of clinical decision-making and the effectiveness of rehabilitation strategies.

Keywords

Patellofemoral pain; dynamic valgus; knee; kinematics

Disciplines

Physical Therapy

File Format

PDF

File Size

555 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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