Patellofemoral Chondromalacia

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

T1

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 seen³such 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

Nonoperative

Patients may be asked to decrease strenuous activities, utilize exercises to increase strength of quadricep muscles, and / or take nonsteroidal anti-inflammatory drugs.⁴

Operative

Arthroscopic debridement and lavage
Articular resurfacing
Surgical correction for instability
Patellectomy⁴
Osteochondral autologous transplant (OAT)
Subchondroplasty
Platelet rich plasma (PRP) or stem cell injection
Joint lubricant injection (e.g. Synvisc®)

Patellofemoral Chondromalacia: Example

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HISTORY:

Pain

sagittal t1w tse coronal t2w spair

Image 1 - Sagittal T1W TSE Image 2 - Coronal T2W SPAIR

Image 3 - Axial PDW SPAIR Image 4 - Sagittal PDW SPAIR

FINDINGS:

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.

CONCLUSION:

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

Epidemiology

Most common in young adults with higher bias towards females.¹Patellar maltracking is the most common cause of knee pain in adolescents without acute trauma.

Pathology: Association

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).