This study will be conducted to investigate the relationship between knee joint pain intensity and joint position sense accuracy in patients with patellofemoral pain syndrome (PFPS) in a single-leg squat position.

Patellofemoral pain syndrome (PFPS) is one of the most prevalent knee problems that interfere with everyday activities and function. The prevalence of Patellofemoral pain syndrome varies, affecting between 22% and 40% of the general population and up to 70% in athletes engaged in running and jumping sports, with a higher incidence reported among females and individuals aged 15-30 years.Impaired proprioception and balance are recognized as intrinsic components in the etiology of PFPS, and research shows that PFPS patients have severe abnormalities in these domains when compared to healthy controls, particularly when performing dynamic tasks. The impaired balance and proprioception are hypothesized to result from altered neuromuscular control, decreased muscle strength, or changes in sensory feedback, which are crucial for maintaining stability and control over movements.The correlation between proprioceptive deficits and PFPS highlights the significance of including balance and proprioception-focused interventions in the PFPS treatment plan, as these can greatly enhance pain, function, and quality of life for those who are impacted. Addressing these deficits may not only improve symptoms associated with PFPS but also reduce the risk of further injury and enhance overall knee function.

To the best of the authors' knowledge, no previous study has specifically correlated knee JPS in a WB position (single-leg squat position) with PFPS. Thus, findings of this study might enhance the evidence-based clinical decisions made by the physical therapists regarding the management of PFPS, justifying for the patients the value of integrating proprioceptive and motor control training alongside traditional strengthening programs to improve functional outcomes. By addressing the neuromuscular factors linked to pain, rehabilitation strategies can become more precise and function-oriented, ultimately improving quality of life and physical performance.

Inclusion Criteria:

• Age ranges from 18-35 years
• BMI ranges from 18-25 kg/m2
• Positive eccentric step test
• Anterior or retropatellar knee pain present during at least two of the following - ascending/descending stairs, hopping/running, squatting, kneeling and prolonged sitting
• Pain on palpation of patellar facets
• Insidious onset of symptoms vague and non-localized pain at anterior of knee for at least three months ( unrelated to a traumatic incident.

Exclusion Criteria:

• Knee pain is more than 6 score on ANPRS.
• History of traumatic patellar dislocation or subluxation
• Osteoarthritis in the knee, ankle or hip joints, injury of cruciate ligaments or menisci
• Previous orthopedic disorders or neurologic deficit of the lower limbs, any sensory problems, leg length discrepancy, neuromuscular disease like multiple sclerosis
• Athletic patients.

eighty two patellofemoral pain syndrome had Positive eccentric step test,Anterior or retropatellar knee pain present during at least two of the following - ascending/descending stairs, hopping/running, squatting, kneeling and prolonged sitting and Pain on palpation of patellar facets. their ages between 18-35 years old.