Outerbridge examined where chondromalacia patellae begins and whether the shape of the femoral condyles could account for its cause.
Case series of 196 medial meniscectomies with patellar cartilage inspected and graded, plus a description of femoral condyle anatomy.
Methods
Design
Observational case series
Patients
196 knees undergoing medial meniscectomy
Basis
Macroscopic appearance of the patellar cartilage
Size of the fissured area
Key Findings
Friction of the medial patellar facet against a rim at the top of the medial femoral condyle may partly explain the cause of chondromalacia.
Lesions were almost always centered in the middle of the medial patellar facet or just distal to it, usually about ½ inch or more across.
A rim 3 to 8 mm high spans the full width of the medial condyle and separates its cartilage from the anterior femoral cortex.
The lateral condyle instead has a smooth skid, and the lateral facet is well onto the cartilage before the medial facet reaches the medial cartilage border.
Roughly half of the 196 patellae showed chondromalacia at meniscectomy, and the rest had healthy cartilage.
Only 37 of 78 bucket‑handle tears had chondromalacia, usually mild, and no relationship appeared between the timing or severity of injury and the patellar lesion.
Board pearl
In Outerbridge's grading, a ½-inch diameter of fragmented, fissured cartilage separates grade 2 from grade 3, and grade 4 means erosion down to bone.
Outerbridge grades of chondromalacia patellaeOuterbridge, J Bone Joint Surg Br 1961
Grade 1
Cartilage softened and swollen
Grade 2
Fragmentation and fissuring over an area ½ inch or less across
Grade 3
Fragmentation and fissuring over an area more than ½ inch across
Grade 4
Cartilage eroded down to bone
Grade 4 on the lateral facet or trochlea, with tibiofemoral cartilage below grade 3, is one indication for patellofemoral arthroplasty.
Authors' conclusion
Rubbing of the medial patellar facet on the rim at the upper border of the medial femoral condyle can explain in part the etiology of chondromalacia.
Outerbridge examined where chondromalacia patellae begins and whether the shape of the femoral condyles could account for its cause.
Case series of 196 medial meniscectomies with patellar cartilage inspected and graded, plus a description of femoral condyle anatomy.
Methods
Design
Observational case series
Patients
196 knees undergoing medial meniscectomy
Basis
Macroscopic appearance of the patellar cartilage
Size of the fissured area
Key Findings
Friction of the medial patellar facet against a rim at the top of the medial femoral condyle may partly explain the cause of chondromalacia.
Lesions were almost always centered in the middle of the medial patellar facet or just distal to it, usually about ½ inch or more across.
A rim 3 to 8 mm high spans the full width of the medial condyle and separates its cartilage from the anterior femoral cortex.
The lateral condyle instead has a smooth skid, and the lateral facet is well onto the cartilage before the medial facet reaches the medial cartilage border.
Roughly half of the 196 patellae showed chondromalacia at meniscectomy, and the rest had healthy cartilage.
Only 37 of 78 bucket‑handle tears had chondromalacia, usually mild, and no relationship appeared between the timing or severity of injury and the patellar lesion.
Board pearl
In Outerbridge's grading, a ½-inch diameter of fragmented, fissured cartilage separates grade 2 from grade 3, and grade 4 means erosion down to bone.
Outerbridge grades of chondromalacia patellaeOuterbridge, J Bone Joint Surg Br 1961
Grade 1
Cartilage softened and swollen
Grade 2
Fragmentation and fissuring over an area ½ inch or less across
Grade 3
Fragmentation and fissuring over an area more than ½ inch across
Grade 4
Cartilage eroded down to bone
Grade 4 on the lateral facet or trochlea, with tibiofemoral cartilage below grade 3, is one indication for patellofemoral arthroplasty.
Authors' conclusion
Rubbing of the medial patellar facet on the rim at the upper border of the medial femoral condyle can explain in part the etiology of chondromalacia.