Dynamic Q Angle and Core Endurance in Adolescent Athletes With Patellofemoral Pain Syndrome

Patellofemoral pain syndrome is a common musculoskeletal condition in adolescent athletes and may be associated with altered frontal-plane knee alignment, reduced proximal trunk control, and lower-extremity flexibility impairments. Sprint athletes are exposed to repetitive high-load and high-velocity movement patterns that require coordinated control of the trunk, pelvis, and lower extremities. However, sex-related differences in the biomechanical profile of adolescent sprinters with PFPS remain insufficiently understood.

This study was designed as an observational, cross-sectional, sex-based comparative investigation involving elite adolescent sprinters aged 15 to 17 years. A total of 150 athletes were enrolled. Three participants had incomplete assessment data and were excluded from the final analysis, resulting in 147 participants with complete data. Participants were classified into four groups according to sex and PFPS status: female sprinters without pain, female sprinters with PFPS, male sprinters without pain, and male sprinters with PFPS.

PFPS status was determined through clinical assessment by a sports medicine physician. The diagnostic assessment included anterior knee pain symptoms, clinical patellofemoral tests, the Anterior Knee Pain Scale, and the Visual Analog Scale. Control participants had no current anterior knee pain or clinical findings consistent with PFPS.

Dynamic Q-angle was assessed during a standardized step-down task using a two-dimensional mobile goniometric application. Anatomical markers were placed over the anterior superior iliac spine, patellar center, and tibial tuberosity. Two repetitions were recorded, and the mean value was used for analysis.

Trunk/core endurance was assessed using the McGill trunk flexion, trunk extension, and lateral endurance tests. Lower-extremity flexibility was evaluated using the Straight Leg Raise test for hamstring flexibility, the Modified Thomas test for hip-flexor flexibility, and the Ober test for iliotibial band and tensor fascia latae tightness. Body composition and relevant demographic and training characteristics were also recorded.

The primary objective was to compare dynamic Q-angle between participants according to sex and PFPS status. Secondary objectives were to compare trunk endurance and lower-extremity flexibility outcomes and to identify independent factors associated with dynamic Q-angle. All measurements were obtained during a single assessment period, and no therapeutic, exercise, pharmacological, or experimental intervention was administered.

Inclusion criteria

Female or male adolescent elite sprinters aged 15-17 years Minimum of two years of regular athletic training Participation in athletic training at least four days per week Possession of a valid track and field license Active participation in sprint events at the national or international level Ability to complete all clinical and biomechanical assessments Written informed consent from the participant and a parent or legal guardian

PFPS Group-Specific Criteria:

Diagnosis of patellofemoral pain syndrome by a sports medicine physician Anterior knee pain localized to the patellofemoral region Positive patellar compression and grind test Anterior Knee Pain Scale score below 80 Visual Analog Scale pain score of at least 3

Control Group-Specific Criteria:

No current anterior knee pain No clinical findings consistent with patellofemoral pain syndrome

Exclusion criteria

History of lower-extremity surgery Acute lower-extremity injury within the previous six months Notable musculoskeletal deformity Arthritis or chronic pain affecting the knee, hip, or ankle Neurological or systemic disease that could affect movement or physical performance Inability to complete the assessments because of excessive pain or insufficient cooperation Incomplete assessment data