Table 2 Pre-Diagnostic Evaluation for Patellofemoral Pain Syndrome (PFPS)

"J Sign" Visualization [80, 81]

Deviation of the patella as the patella engages in the trochlea

• Clinician visualizes the medial deviation during early flexion and the inverted "J" movement of the patella due to tightness of the lateral retinaculum or VMO dysfunction.

• A positive "J sign" involves lateral deviation of the patella during the terminal extension phase.

Ely Test [82]

Decreased quadriceps flexibility, specifically the rectus femoris muscle

• Athlete lies prone while passive flexion of the athlete's knee is produced for full static ROM with pressure placed on distal 1/3 of lower leg over the tibia.

• Examiner places other hand over the region of the intertrochanteric line of the anterior femur.

• If knee flexion causes the athlete's hip on the same side to have a spontaneous flexion contracture, the rectus femoris is deemed to be tight.

• A comparison should be made between both legs.

Ober Test [74]

Tight Iliotibial (IT) band

• The patient is sidelying with the top leg in knee flexion and the bottom knee extended.

• The clinician stabilizes the pelvis with one hand and grasps the ankle to guide the lower extremity with knee flexion into hip extension.

• The upper leg is abducted and extended to keep the thigh in line with the body.

• A positive test is when the leg does not adduct pain-free medially past the midline, and may indicate a tight IT band.

Thomas Test [74, 83–85]

Poor hip flexor flexibility

• The patient lies supine with one leg in hip/knee extension with ankle dorsiflexed.

• The other leg is in hip/knee flexion with ankle dorsiflexed.

• The clinician pushes in the region of the tibial tubercle to create greater hip flexion.

• The patient attempts to gain the greatest (ROM) in hip flexion, while keeping the opposite leg firmly on the ground or examination table.

• If the iliopsoas is tight, the opposite leg with show initiation of hip flexion through a flexion contracture.

Trendelenburg Test [86]

Weak hip abductors

• Clinician observes the patient standing on one leg. • A positive test is a noticeable drop in the pelvis on the opposite side due to hip instability or weak abductors.

Quadriceps Atrophy [58]

Quadriceps circumference asymmetry

• Clinician determines visually or by using a tape-measurement proximal to the patella.

Altered VMO/VL Response Time [1]

Altered VMO muscle reflex time compared to VL

• Clinician's hands are placed on both the muscle belly of the VMO and the VL while the knee is in extension.

• Patient is asked to contract the quadriceps group while the clinical feels for a timing difference between VMO and VL contraction.

• In a normal patient, no timing difference between the contraction of the VMO and VL exists. A positive test is a marked delayed onset of the VMO muscle on palpation.

Vertical Jump/Poor Power Production [39]

Reduction of power production capacity or poor overall lower body force production potential.

• Vertical jump analysis can be performed using a Vertec Device.

• Parameters are not well defined; however any decrease in vertical jump testing shows decreased power production potential. Care must be taken to perform the test in same test environment conditions as different locations and techniques will change outcome.

Q Angle Measurement [48, 55]

Excessive Q angle (greater than 20 degrees)

• Patient stands with the knee in full extension [48].

• Q angle is formed by the line connecting the ASIS and the center of the patella intersects the line connecting the center of the patella with the middle of the anterior tuberosity.

• A Q angle measurement in excess of 20 degrees may lead patient to be at a higher risk for PFPS.

Generalized Ligamentous Laxity [39, 64, 75, 103]

Generalized ligamentous laxity

• Either:

   ◦ Passive 5^th finger digit dorsiflexion beyond 90 degrees.

   ◦ Passive apposition of the thumb to the flexor forearm.

   ◦ Elbow hyperextension in excess of 10 degrees.

   ◦ Knee hyperextension beyond 10 degrees.

   ◦ Ability to place the palms of the hands on the floor while maintaining forward flexion of the trunk with knees straight.

• Having any positive generalized ligamentous laxity characteristics may make the patient higher risk for PFPS.

Patellar Tilt [39, 80]

Lateral retinacular tightness

• Lateral retinacular tightness is determined if the lateral patella cannot be raised to horizontal while compressing the medial patella posteriorly.

• Excessive patellar tilt can be considered positive by the clinician's clinical experience regardless of meeting the exact criteria.