The importance of synovial joint mobilization – scientific basis

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The TMJ is a Synovial Jointmobilebones are separated by a joint cavitysynovial membrane lines the non-

articular surfaces of the joint cavityproduces synovial fluid

THE TMJ FOLLOWS THE SAME BIOLOGICAL RULES AS ALL SYNOVIAL JOINTS

Joints Consist of Connective Tissuecells

chondrocytes osteocytes fibroblasts synovial cells

fibers collagen reticular elastic

ground substance - glycosaminoglycans sodium hyaluronate chondroitin sulfate keratan sulfate

Chondrocytesproduce extracellular

matrixCollagen

Proteoglycans

viability of chondrocytes depends on synovial fluid

Articular Cartilage: ComponentsProteoglycans: osmotically activeCollagen: provides structural support

Articular Cartilage Properties

Compressibility

Resiliency

Synovial Membrane Functionssynovial fluid productionlubricationnutrition of chondrocytes

phagocytosis of substances in joint space

MOTION necessary for joint rehabilitation:diffusion of nutrients from synovial fluid

articular cartilage

nutrition of chondrocytes & maintenance of cartilage

matrix

Articular Cartilage Degradation

•Excessive Joint Loading

•Lack of Joint Motion

MOTION necessary to PREVENT ADHESIONS*

*Orthopaedic Research – 30 yearsAkeson WH, et al. Clin Orthop 219:28, 1987

Salter RB. Clin Orthop 242:12, 1989

Ellis E, Carlson DS. Clin Plastic Surg 16(1):133, 1989

Hydrostatic-weeping Lubrication

DYNAMIC MOTION IN A JOINT CONTINUOUSLY PRODUCES A FLUID LAYER WHICH SEPARATES AND PROTECTS THE OPPOSING ARTICULAR SURFACES

COMPRESSION

boundary lubricationhydrostatic-weeping lubrication

normal cartilage cartilage degradation synovial inflammation

Damaged Joint Tissues

Impaired Joint Lubrication

IMMOBILIZATION EFFECTS JOINTS & SURROUNDING TISSUES

synoviumarticular cartilagemusclesligamentsboneperiarticular connective tissue

Salter RB: Clin Orthop 242:12, 1989Akeson WH, et al: Clin Orthop 219:28, 1987Ellis E, Carlson DS: Clin Plastic Surg 16(1):133, 1989

EFFECTS OF IMMOBILIZATION ON

SYNOVIUM:

obliteration of joint spaceadhesions

EFFECTS OF IMMOBILIZATION ON CARTILAGE

cartilage has no blood supplyjoint motion is necessary for the

pumping action of synovial fluid movement is necessary for cartilage nutrition lubricationrepair

EFFECTS OF IMMOBILIZATION ON

ARTICULAR CARTILAGE:thinning degenerationerosionimpaired nutrition

EFFECTS OF IMMOBILIZATION ON

MUSCLES:

atrophydecreased muscle fiber diameterdecreased blood supply

EFFECTS OF IMMOBILIZATION ON

BONE:osteoporosisinvasion of subchondral bone by

proliferating mesenchymal tissue

EFFECTS OF IMMOBILIZATION ON JOINT CONNECTIVE TISSUES

(DISC, CARTILAGE, CAPSULE, LIGAMENTS)

reduced collagen massreduced matrix componentsreduced water contentincreased degradation compared to

synthesis

SUMMARY EFFECTS OF IMMOBILIZATION ON SYNOVIAL JOINTS:

impaired joint homeostasisimpaired cartilage nutritionarticular cartilage degradationintra-articular adhesionsatrophy of musclessubchondral bone resorptionimpaired lubrication