Lateral ankle sprain (LAS) and patellofemoral pain syndrome (PFPS) are common musculoskeletal conditions associated with postural instability. However, the direction-specific nature of balance deficits and comparative patterns across these conditions remain unclear. Therefore, the aim of this study is to compare overall, mediolateral, and anteroposterior postural stability indices among individuals with LAS, PFPS, and healthy controls using the Biodex Balance System

Inclusion Criteria:

Inclusion criteria for the lateral ankle sprain group will include participants with a clinically confirmed history of unilateral lateral ankle sprain, who are at least three months post-injury to avoid acute inflammatory effects, and who report residual symptoms such as pain or functional limitation. Participants in the patellofemoral pain syndrome group will have a clinical diagnosis of patellofemoral pain syndrome characterized by anterior or retropatellar knee pain aggravated by functional activities such as stair climbing, squatting, or prolonged sitting, with symptoms persisting for at least three months. Healthy control participants will have no history of lower limb musculoskeletal injury, pain, or functional impairment within the past three months and will be matched to the patient groups based on age and sex. All participants across groups will be able to stand independently without assistive devices and will demonstrate sufficient cognitive ability to understand and follow study instructions

Exclusion Criteria:

Exclusion criteria for all groups will include a history of lower limb fracture or surgery, neurological or vestibular disorders that may affect balance or postural control, uncorrected visual impairments, systemic inflammatory or rheumatological diseases, and metabolic or neurological conditions known to influence neuromuscular performance. Participants currently engaged in structured balance, proprioceptive, or neuromuscular training programs, as well as those taking medications that may affect balance or postural stability, will also be excluded from the study.

a total of 90 participants (30 per group) will be required to participate in the study taking into consideration 10% drop out. Participants of both sexes with ages of 20 to 30 years will be recruited and assigned into three groups: individuals with lateral ankle sprain (LAS), individuals with patellofemoral pain syndrome (PFPS), and healthy control participants. All participants will have normal cognitive function and the ability to understand and follow instructions required for balance assessment.