Patella Dislocation

Patella dislocation most commonly occurs when the patella, a large sesamoid bone, shifts laterally out of the femoral trochlear (Mackay et al. 2014). This may happen due to a direct trauma, such as unusual shear force, which may occur whilst playing sport or exercise. However, it may also occur indirectly due to biomechanical variance, such as an increased quadriceps angle, trochlear dysplasia or general patella instability (Cheng et al. 2014). The main mechanism involved in a dislocation is a sudden twisting motion. The ligaments that are involved in stabilising the patellofemoral joint include the patellofemoral, patellomeniscal and patellotibial ligaments. All three of these ligaments help to prevent lateral movement of the patella. The
36). Other Inflammation symptoms that may present are redness, increased temperature, and loss of function. These symptoms will also occur rapidly and in particular, loss of function and pain when attempting to flex or extend the knee. Weight baring is best to be limited in the first few days while inflammation is at its worse (Palmu et al. 2008). However, to prevent severe atrophy of the quadriceps muscles, patients are encouraged to walk without crutches within a few days post injury (Houglum 2010, p. 899). The patellofemoral joint may be immobilized for a period of time. The literature surrounding immobilization is inconclusive, with some studies suggesting 1-3 weeks and others suggesting it is not necessary at all (Rhee et al. 2012). Depending on the severity of damage to the patellofemoral joint, patients will experience different levels of
2004). Adolescent females are at an increased risk of sustaining a patella dislocation, due to increased instability and general weakness in the quadriceps muscles (Sillanpää et al. 2008). As the female pelvis is wider, the Quadriceps angle is increased and a dislocation due to this is more likely to result (Cheng et al. 2014). A family history of dislocations or patella instability increases the likelihood also, due to inheriting patellofemoral joint biomechanical variances (Fithian et al. 2004). As discussed earlier, trochlear dysplasia, the Quadriceps angle and geometric variance leads to an increased risk for dislocation (Cheng et al. 2014). Studies have also identified irregular extensor mechanism alignment, hypermobility syndrome, a tight lateral retinaculum, patella alta and hypoplasia of the vastus medialis oblique as increased risk factors (Cheng et al. 2014) (Sillanpää et al. 2008). These disorders result in a person having either hypermobile structures around the patellofemoral joint or incorrect alignment of the patella, which will in turn increase the likelihood for a dislocation (Sillanpää et al.