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Magnetic resonance imaging, histology, and x-ray of three stages of damage to the knees of STR/ORT mice.

RATIONALE AND OBJECTIVES
The authors develop a scoring system for assessing those features of degeneration of the STR/ORT mouse knee visualizable by magnetic resonance (MR) imaging, and to validate those MR scores by comparison with x-ray and histology.


METHOD
Magnetic resonance imaging, histology, and x-ray have been used in a cross-sectional study to visualize the anatomy and pathology of the knees of three pairs of male STR/ORT mice and their approximately age-matched female pairs. A scoring system was developed that distinguished the faster rate of damage of the males from the slower progressive changes seen in the females.


RESULTS
Changes in the patellar tendon were observed in MR imaging of the 5-month-old male knee. Sagittal images showed other degenerative features such as sclerosis and loss of signal from synovial fluid after 9 months; osteophytes and degeneration of the tibial plateau were better visualized in the coronal plane. Cysts were poorly correlated to the progression of the disease. Similar trends were observed for four features scored in x-rays (sclerosis, joint space narrowing, cysts, and osteophytes) and cartilage degradation assessed using histology. In contrast, the age-matched females were less affected.


CONCLUSIONS
Magnetic resonance imaging can identify joint degeneration in the knees of male mice, which develops more rapidly than in age-matched females. Those observations were validated by radiology and histology.