Resolving Problems of joint-surface wear

1. Resolving Problems of joint-surface wear Management of common musculoskeletal disorder Nargesshakerian Student scientific association of rehabilitation

2. Title and Content Layout with List • Incongruency of synovial joint surfaces, relatively small contact area exists in most positions between joint surfaces • The wedge spaces are necessary for hydrodynamic lubrication • Small area of contact increase the wear between joint surface • Clinicians concern about track bound joints ; humeroulnar ,patellofemoral, ankle mortise ,interphalangeal joints • One or both surfaces contact are the same in habitual Mvt

3. Resolution of joint wear • First the congruency of • Second changing position through mvt • E.g. ; knee , ankle, elbow ,finger

4. Knee • More complex than others, wide WB specially in Flex ( more incongruent) • Significantly incongruent • It must be allow some degree of rotation c⁻ or s⁻ flex & ext or in conjuct rot • Lubrication isnot sufficient ; climbing stairs, squatting, lifting • Another concern ; tendency of femur to slip forward on tibia because of lacke of intrinsic stability and incongruency

5. Because of incongruce and normal heavy loading : • Knee is susceptible to excessive shear forces during mvt • It also delicate to excessive compressive force during W.B(static loading) • Intrinsic instability during Flex. laoding

6. Meniscus *Intra-articular menisci serve as compensatory for unsatisfactory engineering. *the effective load bearing area pressure *intrinsic stability *Contributing in lubrication phenomenon(semicartilaginous)

7. Meniscus

8. Meniscus

9. Note • The degree of slide could not occur normally without the extrinsic control provided by the cruciate , nor without the intrinsic stability provided by the menisci .This type of motion, in which the area of contact of a particular joint surface constantly changes with movement at the joint ,is necessary to allow for the intermittent compression of articular cartilage essential to normal nutrition and lubrication. • Fibrilation of articular cartilage in normal hip and shoulder first occur in non-W.B areas

10. Note • This is perhaps a partial explanation for the frequency of degenerative arthritis occurring in human hip joints; a relatively small surface area is used for weight-bearing, while much of the articular cartilage receives little or no compression. As will be discussed later in the section on arthrosis, it also contributes to the exploration of how abnormal joint arthrokinematicsmay lead to joint pathology.