Femorotibial and patellar cartilage loss in patients prior to total knee arthroplasty, heterogeneity, and correlation with alignment of the knee
- 1Department of Orthopaedics, University of Frankfurt, Frankfurt, Germany
- 2Institute for Anatomy and Musculoskeletal Research, Paracelsus Private Medical University, Salzburg, Austria, and Chondrometrics GmbH, Ainring, Germany
- 3Department of Diagnostic Radiology, University of Frankfurt
- 4Department of Rheumatology, Northwestern University, Chicago, Illinois, USA
- Correspondence to:
Prof Dr med Felix Eckstein
Institute for Anatomy and Musculoskeletal Research, Paracelsus Private Medical University, Strubergasse 21, A 5020 Salzburg, Austria;
- Accepted 14 June 2005
- Published Online First 23 June 2005
Objective: To analyse tibial, femoral, and patellar cartilage loss in patients prior to total knee arthroplasty (TKA), and its correlation with alignment of the knee.
Methods: 26 patients (aged 58 to 86 years) with a clinical indication for TKA were investigated. Quantitative end points of cartilage morphology (T scores for cartilage volume normalised to total subchondral bone area) were determined from coronal and axial magnetic resonance image data, using proprietary software. The static alignment of the knee was determined from standing full limb radiographs.
Results: The magnitude of cartilage loss (T score of normalised cartilage volume) was highly variable within the knee, correlation coefficients ranging from r = 0.17 to 0.51 between cartilage plates. The correlation of cartilage loss with static alignment of the knee (as a continuous variable) was r = −0.52 (p<0.05) for the medial tibia, −0.38 (not significant) for the medial femur, +0.76 (p<0.001) for the lateral tibia, +0.31 (not significant) for the lateral femur, and −0.09 for the patella. When analysing alignment independent of direction (valgus or varus), the correlation for the patella increased to r = 0.30, but remained non-significant.
Conclusions: Cartilage loss was highly variable among patients and among cartilage plates before knee arthroplasty. Its correlation with alignment was stronger for the tibia than for the femur. There was some evidence for an association of alignment and patellar cartilage loss. These findings stimulate further research on the mechanism and cause–effect relation of alignment and knee osteoarthritis using quantitative magnetic resonance imaging technology.
- BMI, body mass index
- cLF, lateral aspect of the femur
- cMF, medial aspect of the femur
- LT, lateral tibia
- MT, medial tibia
- tAB, total subchondral bone area of the cartilage plates
- ThCcAB.max, maximum thickness of the cartilage
- ThCcAB.me, mean thickness of the cartilage, as an average of the cartilage covered area of bone
- TKA, total knee arthroplasty
- VC, cartilage volume
- VCtAB, cartilage volume normalised to body height, body weight, and tAB
Published Online First 23 June 2005