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How might the posterior cruciate ligament be injured?
- when superior part of tibia is struck with knee flexed
- tibia driven posteriorly on femur
- femur is driven anteriorly on tibia
- knee joint severely hyperflexed
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What happens to the flexed knee when posterior cruciate ligament is torn?
flexed knee is unstable
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How do you test the stailty of the PCL?
- tibia is forced in a posterior direction
- if posterior movement occurs, indicates torn PCL
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Why are knee joint injuries common?
it is a major weight bearing joint and stability depends almost entirely on associated mm. and ligaments
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What may cause ligamentous injuries of the knee joint?
any blow that forces knee to move in abnormal plane
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Which ligament is stressed during a blow on the lateral side of the knee when a person is bearing weight on the leg?
tibial collateral ligament
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If blow to the lateral side of the knee is relatively minor, what happens to the fibers?
fibers are stretched and some may be torn
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Sprained tibial collateral ligament:
fibers are stretched and possibly torn from lateral blow to knee
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Torn tibial collateral ligament:
- results from severe blow to lateral knee
- fibers torn partially or completely
- usually occurs near attachment to medial epicondyle of femur
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What is another name of meniscus injury?
knee-cartilage injury
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What suggests injury to the medial meniscus?
localized tenderness/pain in flexed knee on medial side of patellar ligament, just proximal to medial tibial plateau
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Which meniscus is more likely to be injured?
medial meniscus
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What causes injury to medial meniscus?
twisting strain applied to knee joint when flexed
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What is the medial meniscus firmly attached to?
tibial collateral ligament
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Twisting strains of the tibial collateralligament may tear and/or detach what?
medial meniscus from fibrous capsule
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What may happen to part of the torn cartilage if the medial meniscus is torn or detached?
may become displaced toward center ofjoint and become lodged between tibial and femoral condyles
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What happens when a part of the torn medial meniscus becomes lodged between tibial and femoral condyles?
locks the knee in flexed position, preventing patient from fully extending knee
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What may happen as a result of a sudden twist of the knee when weight is borne by the flexed knee joint?
rupture the medial meniscus, splitting it ongitudinally
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What is the blood supply like on the internal edges of the menisci?
poorly supplied with blood
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Since the internal edges of the menisci are poorly supplied with blood, do tears in them heal easily, or poorly?
poorly
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Tears near the peripheral margin of menisci are vascularized by what?
genicular branches of the popliteal artery
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Do tears of the peripheral margin of the menisci heal well or poorly?
well
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Which joint is the most frequently injured major articulation in the body?
ankle joint
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Which ligaments of the ankle joint are most frequently injured?
- lateral ligaments
- -one or more of its four parts may be stretched/orn
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Sprained ankle:
results from twisting of the weight bearing foot and is nearly always a inversion injury
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What are the steps of an ankle injury?
- 1. person steps on an uneven surface and falls
- 2. this stretches most fibers of lateral lig and tears some
- 3. ankle becomes painful and localized swelling/tenderness appears anteriorinferior to tip of lateral malleolus
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What do torn fibers of the lateral lig in sever ankle sprains result in?
instability of ankle joint
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When one or more of the lateral ligaments are stretched or town, the ankle becomes very:
unstable
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What may cause fracture-dislocation of ankle joint?
- sever injuries in which tip of lateral malleolus is avulsed
- foot is fixed against some object and is thrown into inverted position violently transferring body weight to lateral ligaments of ankle
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With fracture-dislocation of the ankle joint, which ligament is usually torn?
calcaneofibular ligament, partially or completely, along with anterior talofibular ligament
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The anterior talofibular ligament is fused with what in the ankle joint?
fibrous capsule
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The peroneus brevis muscle prevets what?
over inversion of foot, aiding the lateral ligaments in prventing severe inversion injuries of ankle joint
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What may the result of violent inversion of the foot be?
avulsion of tuberosity of 5th metatarsal bone, into which tendon of peroneus brevis muscle inserts
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Is flat appearance of the feet of infants normal?
yes
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Why do infants have a flat appearance to their feet?
subcutaneous fatpads in soles of their feet
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Are the arches of the foot present at birth?
yes
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When do the arches of the foot become visible?
when infant has walked for a few months
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Flatfeet in adolescents and adults are caused by:
- fallen arches
- usually medial parts of longitudinal arches
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What help maintain the arches of the foot?
plantar ligaments and plantar aponeurosis
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If the ligaments supporting the arches of the foot become abnormally stretched the plantar calcaneonavicular (spring) ligament can no longer adequately support the head of the talus resulting in what?
- flattening of medial part of longitudinal arch
- concmitant lateral deviation of forefoot
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In the common type of flatfoot, when does the foot resume its arch?
when weight is removed from it
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Flatfeet are common in what type of people?
older persons, esp. if they undertake much unaccustomed standing or gain weight rapidly
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What does added stress on muscles and increaed strain on ligaments supporting the arches do?
cause flatfeet
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What do fallen arches cause?
pain owing to stretching of plantar mm and straining of plantar ligaments
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Why does a callus formation occur on plantar surface of heads of lateral four metatarsal bones with fallen arches?
protective measure where abnormal pressure is exerted
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