Chondromalacia patellae refers to softening and degeneration of the articular hyaline cartilage of the patella and is a frequent cause of anterior knee pain.
Tends to occur in young adults. There is a recognised female predilection.
Patients with chondromalacia patellae usually present with anterior knee pain on walking up or down stairs. Additionally, there may be knee pain when kneeling, squatting, or after sitting for long periods of time. Knee stiffness, crepitus and effusions may also be present. In some cases, a history of patellar dislocation may be present 4.
Chondromalacia patellae can either occur in isolation or secondary to other conditions, including 1-4:
- direct trauma
- patellar dislocation
- chronic patellar instability/subluxation
- patella alta
- quadriceps imbalance
- synovial plicae 3
Plain radiographs of the knee cannot assess for chondral changes directly and can only demonstrate features of osteoarthritis (OA) involving the patellofemoral joint in end-stage disease. A joint effusion may be visible. Lateral and skyline views are more helpful to assess for shallow excavation in the subchondral bone involving the patella.
CT arthrograms can be used to diagnose plicae and focal cartilage defects but are insensitive to early chondral injury 3.
MRI is the modality of choice for assessing patellar cartilage.
- poor sequence for cartilage and surface irregularity and subtle signal change may be inapparent
- areas of hypointensity may be seen in cartilage
- subchondral reactive bone marrow oedema pattern (low signal)
- secondary changes of osteoarthritis may be seen
- best sequences for assessing cartilage
- most patients with chondromalacia patellae have focally increased signal in the cartilage or focal contour defects in the cartilage surface
- abnormal cartilage is usually of high signal compared to normal cartilage
- findings range from a subtle increase in signal to complete loss of cartilage
- the grading system of chondromalacia patellae is based on T2/PD weighted MRI findings and arthroscopic correlation: see chondromalacia grading (Outerbridge method) or modified Noyes
In the absence of an effusion, plicae may be difficult to identify 3.
Treatment and prognosis
Initial management is with a reduction of strenuous activities, NSAIDs and exercises to stretch and strengthen quadriceps muscle (especially vastus medialis) 4.
A variety of operative options exists including 4:
- arthroscopic debridement and lavage: diagnostic but only offers short term symptomatic relief
- articular resurfacing
- surgical correction for instability
General imaging differential considerations include:
- 1. 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. AJR Am J Roentgenol (abstract) - Pubmed citation
- 2. Stoller DW, Tirman PF, Bredella MA. Diagnostic imaging, Orthopaedics. Amirsys Inc. (2004) ISBN:0721629202. Read it at Google Books - Find it at Amazon
- 3. 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. Radiology (abstract) - Pubmed citation
- 4. McMahon PJ. Current diagnosis & treatment in sports medicine. McGraw-Hill Medical. (2007) ISBN:0071410635. Read it at Google Books - Find it at Amazon
- 5. Rose PM, Demlow TA, Szumowski J et-al. Chondromalacia patellae: fat-suppressed MR imaging. Radiology. 1994;193 (2): 437-40. doi:10.1148/radiology.193.2.7972759 - Pubmed citation
- 6. McCauley TR, Kier R, Lynch KJ, Jokl P. Chondromalacia patellae: diagnosis with MR imaging. AJR. American journal of roentgenology. 158 (1): 101-5. doi:10.2214/ajr.158.1.1727333 - Pubmed
- 7. Lund F, Nilsson BE. Radiologic evaluation of chondromalacia patellae. Acta radiologica: diagnosis. 21 (3): 413-6. Pubmed
- 8. Conway WF, Hayes CW, Loughran T, Totty WG, Griffeth LK, el-Khoury GY, Shellock FG. Cross-sectional imaging of the patellofemoral joint and surrounding structures. Radiographics : a review publication of the Radiological Society of North America, Inc. 11 (2): 195-217. doi:10.1148/radiographics.11.2.2028059 - Pubmed
The knee is a complex synovial joint that can be affected by a range of pathologies:
- bone and cartilage
- distal femoral condyle fracture
- tibial plateau fracture (classification)
- patella fracture
avulsion fractures of the knee
- Segond fracture
- reverse Segond fracture
- anterior cruciate ligament avulsion fracture
- posterior cruciate ligament avulsion fracture
- arcuate complex avulsion fracture (arcuate sign)
- biceps femoris avulsion fracture
- iliotibial band avulsion fracture
- semimembranosus tendon avulsion fracture
- Stieda fracture (MCL avulsion fracture)
- patella fracture
- chronic avulsion injuries
- chondromalacia patellae
- osteoarthritis of the knee
- osteochondral defects
- osteochondritis dissecans of the knee
- pattern of bone contusion in knee injuries
- knee fractures
- meniscal lesions
- synovial lesions
- fat pad
- popliteal fossa