MRT-based pilot study to quantify the deformation of the cartilage of the knee joint with healthy persons after kneeling and perching work

Status:

completed 03/2009

Aims:

Aim of the study was to prove if deformation of the cartilage of the knee joint after kneeling and perching work occurs, and if so how strong the effect is and where in the various joint parts if occurs. Further it was to be verified if and in what way these changes decline after one hour recovery time.

Activities/Methods:

As method magnetic resonance tomography (MRT) was used, cause of its non invasive and contrasty display of the cartilage. From the MRT-data the cartilage of the single joint parts as well as the inner and outer meniscus were separated and 3D-reconstructed.
These 3D-bodies were the base of further analysis. A first step was the calculation of the volume, the average thickness and the largeness of the cartilage-bone boundary (CBB). This step enables a statement if in average there are changes in volume or thickness but still delivers no information where it occurs.
In a second step the local thickness of the cartilage was calculated with so called thickness-plots on the CBB. The differences of the local thickness of plots taken before, immediately after and after on hour of recovery time were calculate.
This allowed a statement if, where and how strong a deformation of the cartilage after work-related exposure occurs responses declines after recovery time.

Results:

Excessive cartilage strain is discussed as one potential cause for cartilage degeneration and subsequent osteoarthrithis. This study evaluated the currently unknown dimension of cartilage deformation and localization in knee cartilage (femur, patella, tibiae) after enduring in different squatting and kneeling postures.
Ten healthy volunteers (five female, five male) were examined before and after accomplishment of a ten minutes lasting loading interval as well as after 90 min. of rest in a 3 Tesla scanner with a high-resolution cartilage dedicated sequence (FLASH-3D-WE-sequence). Four different loading positions were evaluated, consisting of ten min. kneeling in 90°, sitting on the heels and squatting respectively. Additionally 50 knee bends were examined for obtaining comparison data to current literature. Resulting cartilage deformation indicates contact zones of the patello-femoral and femoro-tibial joint compartments, which appear to be functionally plausible - however associated with considerable intraindividual and interindividual variances. After extreme flexion as in sitting on the heels changes were accentuated in the cartilage of the caudal patella, centromedial lateral tibia, trochlea and the dorsal femoral condyles, while after squatting changes were accentuated in the lateral patella, anterolateral tibia and at the lateral aspect of the medial femoral condyle. Deformation after 90° kneeling were located in the central regions of the patellar and lateral tibia cartilage and diffusely in the femoral cartilage, while deformations after knee bends were located in the caudolateral patella, diffusely in the femoral cartilage and at the intercondylar region of both tibiae cartilage plates. This study first present partial interindividual comprehensive deformation zones for defined loading positions.
The detected cartilage deformation between 1 % and 5 % with respect to volume and mean thickness lay within the magnitude of change after everyday activity and moderate sports, e.g. 50-100 knee bends or cycling for ten minutes. The changes were small, but consistent with previous biomechanical examinations which postulate that the contact forces on the joint cartilage is elevated during the process of kneeling, but diminishes in the final static kneeling and squatting position due to additional support by ground and soft tissue contact. These data provide a first approach for the identification of the cartilage contact zones associated with squatting and kneeling postures. They provide a base for comparison to degenerative changes in osteoarthritis patients and might also serve as a database for the development of biomechanical models.

Last Update: