Patellar Cartilage Lesions Research Articles

Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer.

This retrospective study determined that the outcome from anteromedialization of the tibial tubercle correlates well with the location of patellar articular lesions. Detailed descriptions of patellar articular cartilage lesions were obtained from the operative reports of 36 patients who had anteromedialization performed between February 1984 and March 1994. The patterns fell into four distinct groups. Ten patients with type I (distal) patellar lesions and 13 patients with type II (lateral facet) patellar lesions had 87% good to excellent subjective results, and 100% of these patients said they would have the procedure done again. Nine patients with type III (medial facet) lesions had 55% good to excellent results, and 5 patients with type IV (proximal or diffuse) lesions had only 20% good to excellent results. Patients with type I or II lesions were significantly more likely to have good or excellent results than those with type III or IV lesions. Central trochlear lesions were associated with medial patellar lesions and all patients with central trochlear lesions had poor results. There was no significant correlation between the Outerbridge grading of the patellar lesion and the overall results. Workers' compensation issues diminished the likelihood of a satisfactory outcome by 19%; however, this was not statistically significant. This is the first study to correlate the patellar articular cartilage lesion with outcome after tibial tubercle transfer.

Comparison between magnetic resonance imaging and arthroscopy in the diagnosis of patellar cartilage lesions

A blind and prospective study was conducted to assess the accuracy of magnetic resonance imaging (MRI) for diagnosing patellar cartilage lesions. Thirty-three consecutive patients undergoing knee arthroscopy were examined by MRI prior to surgery. Imaging was performed in the axial plane on a 1.5-Tesla unit with spin-echo and gradient-echo T1 and T2 sequences. The MRI and arthroscopic data were compared using a four-grade classification and a patellar map which divided the patellar surface into four quadrants. The overall sensitivity of MRI was 84.7% and the specificity 97.2%. The same pit-fall led to two MRI false positives. A perfect correlation of grading was obtained in 76.5%. When discordance was found, the tendency with MRI was commonly to underestimate the grade of the lesions. The MRI accuracy was high in this study in spite of a high rate of low-grade lesions which are difficult to assess. Related criteria for cartilage assessment with MRI and arthroscopy are suggested for further studies.

Patellar cartilage lesions: in vitro detection and staging with MR imaging and pathologic correlation.

Fourteen freshly disarticulated knee specimens were studied to assess the usefulness of magnetic resonance (MR) imaging in the detection and correct staging of patellar chondral lesions. Axial and sagittal images were obtained; T1-weighted spin-echo sequences were found satisfactory for defining cartilage morphology. Specimens were sectioned and examined grossly for cartilage changes such as softening, blistering, fibrillation, fissuring, and frank subchondral bone exposure. In a side-by-side comparison, all lesions classified grossly in the Shahriaree system as stage II or higher showed MR changes. Stage I changes could not be identified in disarticulated specimens. Stage III lesions showed cartilage irregularity (ulceration) or a loss of the normal, sharply defined margin between coapted cartilage, which represented "crabmeat" fibrillation. Stage IV lesions showed ulceration to bone, sometimes with subchondral bone changes. In this in vitro, preliminary study, MR imaging was found to be an accurate means for detecting and staging moderate and advanced patellar cartilage lesions.

A stress analysis of the patella, and how it relates to patellar articular cartilage lesions

The pathogenesis of three types of lesion of the articular cartilage of the patella are described. Stress analysis of the patella mid-sections show that for large values of ‘ Q’ angle, a wide area of the medial articular surface is under tensile stress. In those patients who have short medial and ‘odd’ facets, the tensile stress generated could lead to fatigue failure of the cartilage producing open chondromalacic lesions commonly observed on the medial aspect of the patella. Vertical tensile stress can occur over the medial side of the lateral facet. If tensile stress is combined with high contact stresses applied normal to the surface, there exists a situation of very high shear stress which may fatigue the deeper layers of the articular cartilage, leading to the closed chondromalacic type of lesion centred on the median region and commonly extending on to the lateral facet. A third rare type of lesion, termed chondrosclerosis, may be caused by an extreme compression phenomenon as a result of the high bending stress combined with the high contact stress over the lateral lacet. The effect of surgical procedures on these stresses is considered.