Lateral Patellar Compression Syndrome (Excessive Lateral Pressure Syndrome)

Excessive lateral pressure syndrome, also called lateral patellar compression syndrome, is caused by a tight lateral retinaculum that tilts the patella laterally and concentrates load on the lateral patellofemoral facet, producing excessive lateral pressure, anterior knee pain and, over time, lateral facet cartilage wear. The defining concept is that the patella is tilted, not subluxing or dislocating, so this is a problem of pressure and tilt rather than instability, which is an important distinction because it changes management. I diagnose it clinically with the patellar tilt test: with the knee extended and the quadriceps relaxed, I try to lift, or evert, the lateral edge of the patella, and in this syndrome the tight lateral retinaculum prevents the lateral patella being everted past the horizontal or neutral. There is lateral patellofemoral tenderness and anterior knee pain worse with activity and prolonged sitting. The key imaging is an axial skyline or Merchant view, which shows an abnormal patellar tilt angle and lateral patellofemoral angle, and CT or MRI confirm lateral tilt without subluxation and assess the lateral facet cartilage; I would also look for trochlear dysplasia or a high TT-TG distance that would point to maltracking or instability and change my plan.

I would manage it conservatively first, because most patients improve without surgery. That means activity modification and analgesia together with a rehabilitation programme that specifically stretches the tight lateral structures - the lateral retinaculum and iliotibial band - and strengthens the vastus medialis obliquus and the hip abductors and external rotators, with patellar taping or bracing to medialise the patella. If the patient has genuine, refractory excessive lateral pressure syndrome - a tight lateral retinaculum with a positive tilt test and abnormal tilt angles on skyline imaging, and no instability - then an arthroscopic lateral retinacular release, sometimes combined with a lateral patelloplasty, is an effective minimally invasive option that corrects the tilt, relieves pain and improves function, although outcomes are poorer if the lateral facet already has high-grade cartilage damage. The crucial caveat is that lateral retinacular release is for tilt and compression, not for instability: a randomised trial found no benefit from adding a routine lateral release to MPFL reconstruction in recurrent patellar dislocation, and an inappropriate or over-aggressive release in an unstable or lax patella can actually worsen instability and cause medial subluxation. So I reserve release for the genuinely tight patella, and treat instability with medial-sided and bony procedures instead.