Knee
Patellofemoral Pain Syndrome
슬개대퇴 통증증후군
Anterior knee pain from patellar maltracking and patellofemoral cartilage stress
- How common
- Common (Young Women, Runners)
- Typical age
- Ages 10–30
What is it?
Patellar maltracking (lateral tilt/tilt) causes abnormal patellofemoral contact stress, irritating cartilage and subchondral bone. Weak VMO, tight IT band, and Q-angle contribute.
Commonly affected: Patellofemoral cartilage, particularly lateral patellar facet
How it develops
- Lateral Patellar MaltrackingWeak VMO + tight lateral structures (IT band, lateral retinaculum) tilt patella laterally
- Increased Cartilage StressMaltracking reduces patellofemoral contact area, increasing focal cartilage pressure
- Subchondral Bone IrritationPain receptors in subchondral bone activated by abnormal compressive forces
- Activity OverloadRunning, stairs, and squatting maximally load the patellofemoral joint
Symptoms
- Anterior Knee PainDiffuse peripatellar or retropatellar aching pain
- Theater SignPain with prolonged sitting (theater sign) — flexion position loads patellofemoral joint
- Worse Descending StairsDescending stairs maximally loads patellofemoral joint — most consistent finding
- Patellar CrepitusGrinding/crepitus with knee flexion — patellar cartilage roughness
- Minimal/No EffusionMinimal or absent effusion — helps distinguish from meniscal or ACL pathology
How it is examined
- Patellar Compression TestCompress patella into trochlea while patient contracts quad — reproduces pain
- J-Sign (Lateral Patellar Tracking)Patella tracks laterally in a J-shape during knee extension — indicates maltracking
- VMO WeaknessWasting or weakness of vastus medialis oblique (VMO) — key contributor
Imaging
Axial (Merchant/sunrise) view assesses patellar tilt, lateral displacement, and trochlear morphology.
- Lateral patellar tilt
- Decreased medial patellofemoral joint space
- Possible trochlear dysplasia
MRI evaluates patellar cartilage, tracking, lateral retinacular tightness, and bone marrow edema — especially in refractory cases.
- Lateral patellar chondromalacia
- Patellar subchondral bone marrow edema
- Lateral retinacular thickening
- Patellar maltracking
Non-surgical care
- VMO StrengtheningTargeted VMO strengthening (terminal knee extensions, step-ups) is the cornerstone
- IT Band + Lateral Retinaculum StretchingStretching lateral structures reduces patellar tilt and lateral compression
- Patellar Taping / McConnell TapingMedially directed taping improves tracking — immediate pain reduction during rehab
- Activity ModificationReduce running/stair volume; substitute low-impact activities (cycling, swimming)
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
Failed 6+ months conservative care; severe chondromalacia or trochlear dysplasia
Procedures that may be discussed
- Lateral retinacular release
- Tibial tubercle anteromedialization (TTO)
- Trochleoplasty for trochlear dysplasia
Outlook
80–90% improve with conservative management. Recurrence common if training errors not corrected.