Patellofemoral chondromalacia is when anterior knee pain results from degeneration of the articular hyaline cartilage of the patella.1
Patellofemoral Chondromalacia: Clinical Presentation
Walking on stairs, kneeling, squatting, or extended sitting times may cause patients anterior knee pain, stiffness, crepitus, or effusions.4
Patellofemoral Chondromalacia: Differential Diagnosis
- Dorsal defect of the patella: on the superolateral corner of the knee
- Bone marrow edema at the inferior pole as a result of
- Jumper’s knee / Sinding-Larsen-Johansson disease
- Patellar sleeve fractures1
- Magic angle
- Osteochondritis dessicans
- Bi- and tri- partite patella
Patellofemoral Chondromalacia: MRI
- Cartilage and surface irregularity may result in subtle signal change
- Cartilage may show areas of intrasubstance hypointensity due to alteration of the proteoglycan milleau
- Subchondral reactive bone marrow oedema pattern may produce a low signal
- Secondary changes of osteoarthritis may be seen3 such as spurring, remodeling, and bony hypertrophy
T2 / PD
- Cartilage is best assessed with small field of view 3D this sections
- Focally increased signal in the cartilage, or contour defects in the cartilage surface (“blisters”)
- Abnormal cartilage generates a higher signal than normal cartilage
- A T2 / PD weighted MRI finding to arthroscopic correlation is used to grade Chondromalacia patellae3
- Stratification is the hallmark of organized healthy cartilage. Deeper layers near the osteochondral plate are consistently “darker”, whereas superficial layers are uniformly “brighter”. This consistent signal pattern is a sign of healthy glycosaminoglycan and proteoglycan composition.
Patellofemoral Chondromalacia: Treatment
Patients may be asked to decrease strenuous activities, utilize exercises to increase strength of quadricep muscles, and / or take nonsteroidal anti-inflammatory drugs.4
- Arthroscopic debridement and lavage
- Articular resurfacing
- Surgical correction for instability
- Osteochondral autologous transplant (OAT)
- Platelet rich plasma (PRP) or stem cell injection
- Joint lubricant injection (e.g. Synvisc®)
Patellofemoral Chondromalacia: Example
Click here to launch this case
Image 1 - Sagittal T1W TSE Image 2 - Coronal T2W SPAIR
Image 3 - Axial PDW SPAIR Image 4 - Sagittal PDW SPAIR
There is a small joint effusion.
The anterior and posterior cruciate ligaments are intact.
There is a small horizontal tear of the body of the medial meniscus.
There is a small complex tear of the inner one-third of the body of the lateral meniscus.
The quadriceps tendon and patellar tendon are intact.
The medial and lateral collateral ligaments are intact.
There is severe patellofemoral chondromalacia with a 6mm full-thickness erosion (images 1 and 2, green arrows, trochlear erosions) (image 3, green arrow, subchondral erosions) (images 4, green arrow, patellar erosion) involving the medial facet of the patella and associated subchondral cyst formation.
There are moderate medial compartment osteoarthritic changes with a 6mm full-thickness erosion involving the weightbearing surface of the medial femoral condyle.
No osteochondral defect or fracture identified.
There are deep infrapatellar bursitis and prepatellar bursitis.
1. Small horizontal tear of the body of the medial meniscus.
2. Small complex tear of the inner one-third of the body of the lateral meniscus.
3. Severe patellofemoral chondromalacia with a 6mm full-thickness erosion involving the medial facet of the patella and moderate medial compartment osteoarthritic changes with a 6mm full-thickness erosion involving the weightbearing surface of the medial femoral condyle and mild lateral compartment osteoarthritic changes.
4. Deep infrapatellar bursitis and prepatellar bursitis.
Patellofemoral Chondromalacia: Appendix
Most common in young adults with higher bias towards females.1 Patellar maltracking is the most common cause of knee pain in adolescents without acute trauma.
Occurance can take place in isolation, but also in association with:
- Direct trauma
- Patellar dislocation
- Chronic patellar instability / subluxation
- Patella alta
- Quadriceps imbalance
- Synovial plicae” 3
Patellofemoral Chondromalacia: References
- Bell DJ, Farooq S, et-al. Chondromalacia Patellae: Radiopaedia (sourced 10Jan2018): https://radiopaedia.org/articles/chondromalacia-patellae
- Gagliardi JA, Chung EM, Chandnani VP et-al. Detection and staging of chondromalacia patellae: relative efficacies of conventional MR imaging, MR arthrography, and CT arthrography. AJR Am J Roentgenol. 1994;163 (3): 629-36.
- Hodge JC, Ghelman B, O'brien SJ et-al. Synovial plicae and chondromalacia patellae: correlation of results of CT arthrography with results of arthroscopy. Radiology. 1993;186 (3): 827-31.
- McMahon PJ. Current diagnosis & treatment in sports medicine. McGraw-Hill Medical. (2007).