prepatellar bursa


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Related to prepatellar bursa: suprapatellar bursa

subcutaneous prepatellar bursa

[TA]
a bursa in the deep subcutaneous tissue, superficial to the fascia lata or superficial prepatellar aponeurosis.

prepatellar bursa

Etymology: L, prae + patella, small dish; Gk, byrsa, wineskin
a bursa between the tendon of the quadriceps muscle group and the lower part of the femur continuous with the cavity of the knee joint.

pre·pa·tel·lar bur·sa

(prē-pă-tel'ăr bŭr'să)
A bursa between the skin and the lower part of the patella.

knee

ginglyomoarthroidal joint between inferior femur and superior tibia; permits sagittal-plane flexion and extension of tibia on femur, and transverse rotation of femur on (static) weight-bearing tibia; at any one time only a small area of each convex femoral condyle articulates with the central area of each slightly concave tibial condyle; the space at the periphery of these articulations is infilled by a C-shaped rim of fibrocartilage (menisci) which deepen the articular cup for the distal femur; assists leg shock absorption and deceleration mechanisms (maximum foot pronation coincides with knee flexion during the gait cycle)
  • clergyman's knee; infrapatellar bursitis infrapatellar bursal inflammation and swelling due to chronic trauma, e.g. prolonged kneeling

  • housemaid's knee; prepatellar bursitis prepatellar bursal inflammation and swelling due to chronic trauma, e.g. prolonged scrubbing a floor

  • kneecap see patella

  • knock knee genu valgum; normal childhood positional variant of the knee joint (e.g. children from 2 to 6 years); thence resolves spontaneously, but may persist into adulthood, creating functional hindfoot varus (see genu valgum)

  • locked knee prevention of knee movement due to pain, swelling or arthropathy

  • overuse knee injury variable and varying, generalized or localized knee pain secondary to altered knee alignment or altered synchronicity of lower-limb function (+ associated lower-limb pathomechanical problem [e.g. excess foot pronation; tibial varum]) or muscular imbalance increasing knee misalignment; treatment includes diagnosis of pathomechanical problem by gait analysis, bespoke corrective orthoses, and rehabilitative exercises (Table 1 and Table 2)

  • rotational knee pain knee pain caused by excessive horizontal plane rotation (torque), e.g. excessive subtalar joint pronation leading to knee joint capsular strain and associated mistracking of patella and medial collateral ligament

Table 1: Stages in the pathology of chondromalacia patellae
StageClinical features
ISoftening or degeneration of the articular cartilage
IICleaving of articular cartilage
IIICleaving and fronding of the articular cartilage
IVErosion of cartilage and underlying bone sclerosis
Table 2: Biomechanical problems associated with predisposition to overuse knee injury
ProblemCharacteristics
Knee stiffnessThe knee is fully extended at heel strike and should flex easily immediately after heel strike to facilitate the absorption of the shock of heel strike
Knee flexion is facilitated by transverse plane motion where the medial condyle of the distal femur rotates medially on the medial platform of the superior tibia; where transverse plane motion is limited (as in coxa valga/genu varum, coxa vara/genu valgum) knee flexion will be less efficient
Where knee flexion is compromised, increased stress is imposed on its structures
Loss of subtalar joint (STJ) pronationShock absorption is also facilitated by STJ pronation; where STJ pronation is limited (as in hindfoot varus or tibial varum) or where the STJ functions routinely at the limit of its range of motion (such as in an abducted foot ± hallux limitus), greater forces are transmitted to the knee with resultant tissue strain
Structure of the kneeThe collateral ligaments of the knee and the menisci are at greatest risk of injury at the point of maximum foot pronation and knee flexion
Ground reaction force (GRF)STJ pronation and knee flexion are initiated by GRF; GRF increases tibial shearing forces which, combined with femoral rotation, can induce knee injury
Excess foot pronationKnee extension creates a stable support limb during propulsion
During propulsion the pelvis and femur rotate externally, but the weight-bearing tibia cannot rotate externally if the foot is excessively pronated, creating a torque on the knee joint, medial knee strain and patellofemoral pain
Gastrocnemius actionDuring knee extension the gastrocnemius is passively stretched and maximally efficient, allowing transfer of power from the quadriceps to the ankle. Once the knee is flexed, gastrocnemius is relaxed and not efficient, and only soleus contraction effects ankle plantarflexion

Knee injuries may be induced by transverse-plane compensation for structural deformities in the lower leg or foot.