Copyright 2009
Definition
Chondromalacia patellae (aka runners knee, patellofemoral pain syndrome) is a disorder of the patellar cartilage surface which describe softening, fissuring, and sometimes bony degenerative changes in th cartilage. This is a problem that can affect both sexes at any age, but is most common in the young female patient.
It is characterized by pain under the patella which is exacerbated with stair climbing or descending, and any activity involving strenuous quad contraction. The pain can be along the medial and lateral retinaculum as well as the patellar tendon as well.
There are many proposed causes including an increased Q-angle, genu valgum, weakness of the VMO or tightness of the quads, patella alta, and femoral or tibial torsion to name a few.
The patients can have pain in the early stages without any structural damage. With longer duration of symptoms, cartilage degenration can occur and is staged as stage I when there is swelling and softening of the cartilage, stage II when the cartilage begins to fissure, stage III when there are fasciculations and damage nearly to the subchondral bone, and stage IV has with bone exposed secondary to missing cartilage. Patients can often have a tight lateral retinaculum and a weak medial VMO.
History will reveal that patients many times have complaints of anterior knee pain under the patella which is worse with activities. Often times patellar tracking is poor with the patella sliding lateral with the knee in full extension (the J sign). Patellar tracking is best observed with the patient sitting upright with the leg dangling off the bed and then looking at the tracking as the knee is extended. Crepitus can be present but doesn’t necessarily imply pathology.
Imaging includes the use of plain x-rays looking at an AP, lateral (for patella alta), and the sunrise view. High quality MRI (3 tesla preferable) can show chondral changes to the undersurface of the patella.
The mainstay of treatment is physical therapy which focuses on strengthening the VMO and stretching the lateral structures. Bracing and taping can be used as well. NSAIDs can be helpful. Orthotics can sometimes help if the patient has significant pes planus. Surgery is reserved for those who fail at least 6 months of non-operative management. Surgery can entail lateral release and occasionally tibial tuburcle osteotomies with realignment procedures such as the Fulkerson (anteromedialization of the tuburcle).
References
http://www.wheelessonline.com/ortho/chondromalacia_of_the_patella