Effect of Specific Versus General Hamstring Stretch on Clinical Outcomes in Patellofemoral Pain Syndrome (PFPS)

Effect Of Hamstring Stretch On Clinical Outcomes In Patellofemoral Pain Syndrome

This randomized, Single-blind, parallel-group trial will compare the effects of three hamstring stretching interventions-general hamstring Muscle Energy Technique (MET), medial hamstring MET, and lateral hamstring MET-each combined with standardized TENS and progressive hip/knee strengthening, on hamstring flexibility (knee-extension ROM), anterior knee pain (Arabic Kujala score), pain intensity visual analogue scale (VAS), and lower-limb strength (hand-held dynamometer) in adults with patellofemoral pain syndrome (PFPS).

Patients with chronic PFPS will be randomized (1:1:1) into:

General MET group: standard non-specific hamstring MET stretch

Medial MET group: targeted medial-hamstring MET stretch

Lateral MET group: targeted lateral-hamstring MET stretch

All groups receive:

TENS: 20 min asymmetric biphasic square-pulse, 120 μs pulse width, 180 Hz, electrodes around patella (5-7 cm apart)

Strengthening: 3×/week for 4 weeks; hip/knee exercises, start 3×10 reps → 3×20, progress with weights or resistance bands.

Outcomes are measured pre-intervention and at 4 weeks. Analysis by mixed-design MANOVA (α < 0.05).

Inclusion Criteria:

• Anterior or retropatellar knee pain lasting at least three months
• Pain reproduced by at least two functional tasks: squatting, kneeling, prolonged sitting, stair climbing, hopping or running
• Pain intensity of ≥3 on a Visual Analog Scale
• positive active knee extension test (inability to achieve greater than 160° of knee extension with the hip at 90° of flexion)
• Body mass index (BMI) < 30 Kg/m² and > 18Kg/m²

Exclusion Criteria:

• Previous knee surgery
• History of knee pathologies, such as meniscal injury' ligament injury, or knee osteoarthritis
• Psychological, cardiovascular' or neurological disorders
• Dizziness or fainting while doing exercises, pregnancy, or any contraindications to exercise
• Physical therapy treatment in the last 3 months