Prevalence of abnormal findings in 230 knees of asymptomatic adults using 3.0 T MRI

Abstract

Objective: To identify abnormalities in asymptomatic sedentary individuals using 3.0 Tesla high-resolution MRI.

Materials and methods: The cohort comprised of 230 knees of 115 uninjured sedentary adults (51 males, 64 females; median age: 44 years). All participants had bilateral knee 3.0 T MRIs. Two senior musculoskeletal radiologists graded all intraarticular knee structures using validated scoring systems. Participants completed Knee Injury and Osteoarthritis Outcome Score questionnaires at the time of the MRI scan.

Results: MRI showed abnormalities in the majority (97%) of knees. Thirty percent knees had meniscal tears: horizontal (23%), complex (3%), vertical (2%), radial (2%) and bucket handle (1%). Cartilage and bone marrow abnormalities were prevalent at the patellofemoral joint (57% knees and 48% knees, respectively). Moderate and severe cartilage lesions were common, in 19% and 31% knees, respectively, while moderate and severe bone marrow oedema in 19% and 31% knees, respectively. Moderate-intensity lesion in tendons was found in 21% knees and high-grade tendonitis in 6% knees-the patellar (11% and 2%, respectively) and quadriceps (7% and 2%, respectively) tendons being most affected. Three percent partial ligamentous ruptures were found, especially of the anterior cruciate ligament (2%).

Conclusion: Nearly all knees of asymptomatic adults showed abnormalities in at least one knee structure on MRI. Meniscal tears, cartilage and bone marrow lesions of the patellofemoral joint were the most common pathological findings. Bucket handle and complex meniscal tears were reported for the first time in asymptomatic knees.

Keywords: Elderly; Knee injuries; Pain-free; Radiology.

Fig. 1

Coronal proton-density fat-saturated MR images (a, c) and sagittal images (b, d) demonstrate bucket handle tear (a, b; arrowheads) in the left knee of a 54-year-old man, and complex macerated (c, arrowheads; d, circle) meniscal tear in the right knee of a 57-year-old woman

Fig. 2

Axial proton-density fat-saturated MR images (a, c), coronal (b) and sagittal images (d) of high-grade bone marrow oedema lesion (grade 3: diameter ≥ 20 mm; in the (a) patella of the left knee of a 40-year-old man, (b) tibia of the right knee of a 59-year-old man; arrowheads) and high-grade cartilage defect (grade 4: full thickness defect exposing the bone; in the (c) patella of the left knee of a 44-year-old woman; arrow; with subchondral bone marrow oedema, arrowhead; (d) femur of the right knee of a 31-year-old woman; arrow; with subchondral ganglion cyst; small arrowhead)

Fig. 3

Axial proton-density fat-saturated MR images of (a) patellar tendons (a.0, grade 0; in the left knee of a 40-year-old man; a.1, grade 1; in the right knee of a 62-year-old man; a.2, grade 2; in the left knee of a 56-year-old man; a.3, grade 3; in the right knee of a 44-year-old man) and (b) quadriceps tendons (b.0, grade 0; left knee of a 40-year-old man; b.1, grade 1; in the right knee of a 40-year-old woman; b.2, grade 2; in the left knee of a 44-year-old man; b.3, grade 3; in the right knee of a 48-year-old man). The tendons are indicated by red arrows or circles; grade 0: normal tendon appearances; grade 1: increased signal intensity in less than 25% of the axial cross-sectional tendon width; grade 2: increased high-signal intensity in 25 to 50% of the axial cross-sectional tendon width; grade 3: increased high-signal intensity occupying more than 50% of the axial cross-sectional tendon width