KNES 372 Lecture Notes - Lecture 6: Epiphysis, Enthesis, Fibrocartilage
25 Sep 2018
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Muscle and Tendon Injury
Tendons
• Collagen tissue
• Connects muscle to bone
• Transfer force from muscles into skeletal system
• Excellent tensile properties
• Tendons have clear, parallel structure when they are healthy. Ligaments may be parallel or
oblique.
• They are constructed of tropocollagen, microfibrils, subfibrils, fibrils, and fascicles. They also
have blood vessels and epithelial surround
• Enthesis is the junction between a tendon and a bone.
o Tendons attach to bone via fibrocartilage and calcified (mineralized) fibrocartilage and
collagen fibres penetrate the fibrocartilage into the subchondral bone.
o Sometimes related to chronic diseases like diabetes
• Myotendinous Junction (MTJ) is the connection between muscle and tendon. This area is very
injury-prone because it is the weakest link of the muscle-tendon system
o Force generated by muscle contraction is transmitted from muscle to
tendon
• Stress-strain curve for tendons – relationship between stress and deformation of
tendons is the same as for ligaments
• In the elastic zone, the tendon behaves like a spring. Ruptures occur when
stretched over the yield point – first single fibres, then total rupture
• Tendons adapt to training by increasing tendon strength through collagen synthesis
• Training every 2-3 days is most likely a sufficient stimulus for tendon protein generation
• Unlike ligaments, tendons don’t need maximal load to gain maximal strength
• INJURIES: may be acute (ruptures, direct traumas, etc.) OR overuse (usually the case)
• Tendon ruptures: acute rupture of a normal and healthy tendon is rare – there is usually
underlying pathology (usually asymptomatic, rupture occur without warning)
o Commonly occurs in athletes and recreational exercisers aged 30-50 years (explosive
sports + degenerative changes)
• Acute tendon ruptures usually occur in connection with eccentric force generation – can occur
in midtendon structures or at the bone-tendon junction area (called avulsion fractures)
