Relation between cartilage volume and meniscal contact in medial osteoarthritis of the knee

BACKGROUND

The purpose was to determine the relationship between the cartilage volumes in different regions of the femur and tibia, and the lengths of contacts between the meniscus and cartilage. The rationale was that less meniscal contact would make the cartilage more susceptible to loss of volume due to degeneration and wear.

METHODS

Fifty MRI scans of osteoarthritic knees at varying degrees of severity were obtained. Computer models of the cartilage layers of the distal femur and proximal tibia were generated, from which cartilage volumes and thicknesses were calculated for different regions. The lengths of meniscal contact and heights were measured in frontal and sagittal views.

RESULTS

Cartilage loss progressed initially on the central and inner regions of the distal femur, and on the tibia in the region uncovered by the meniscus. As the cartilage volume decreased further, the wear spread medially, and to a lesser extent anteriorly and posteriorly. There were inverse relations between the loss of volume on both the femur and tibia, and the meniscal contacts and heights.

CONCLUSIONS

Cartilage loss initially occurred where there was direct contact between the cartilage of the femur and tibia. The meniscus did not prevent this, nor prevent the spread of the wear medially. This may have been due to the progressive reduction of cartilage-meniscal contact as the meniscus subluxed or lost substance, as the cartilage loss and deformity progressed. This suggested that the meniscus was not able to ameliorate the forces and pressures on the cartilage surfaces to prevent degeneration.

Future directions in knee replacement

The use of artificial joints for the treatment of osteoarthritis is expected to expand considerably over the next decade. While newer technologies can offer yet further improvements in total knee systems, implementation will be strongly affected by the need to satisfy apparently competing requirements. Patients expect quicker rehabilitation, improved performance, and lifelong durability; on the other hand, economic constraints require a reduction in cost for each procedure, as well as early intervention and preventative measures, while there is increased pressure from health care systems to use evidence-based medicine as the standard of choice for implants and techniques. The success of a knee replacement depends on the design itself, the surgical technique, the rehabilitation, and, not least, the patient. The major goal of the implant design can be redefined as a restoration of normal knee mechanics, whether by maximum preservation of tissues, or by guiding surfaces that replace their function. Surgical technique needs to be less invasive but achieve optimal patient-specific alignment and soft tissue balancing. Rehabilitation procedures must achieve the expectations of realistic patients. Testing and evaluation methods need to be upgraded for enhanced predictability. This paper discusses current trends and future possibilities to address this expansive scope of design criteria.

A group for "wandering" institutionalized clients with primary degenerative dementia

The authors implemented a group in a state psychiatric institution for women with primary degeneration dementia. The group provided scheduled opportunity in a nonrestrictive environment for structured movement and sensory stimulation. Over a period of nine sessions, small but significant changes were noted in the members' behavior. This type of therapy can benefit such limited clients by enhancing the quality of their life in the institution.