HWN Suggests

Need to Know: Patellar Dislocation

The procedure itself is not challenging, but pain management and related injuries can be troublesome for some patients. The concern for additional injuries such as patella fracture, quadriceps tendon rupture, meniscal or ligamentous tears, and distal femur and proximal tibial fractures should be on your radar.

The bottom line: traumatic knee injuries, especially those with a high suspicion of patella dislocation, should be imaged!

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Articles of Interest

Diagnosis Patella Dislocation

Manual reduction is achieved by placing the patient in the supine position with the hip on the affected side slightly flexed to relax the quadriceps muscle. Firm but gentle continuous pressure is place on the medical aspect of the laterally dislocated patella, while the affected leg is extended. Post-reduction radiographs should be performed to identify associated fractures. Ligamentous stability of the knee also should be determined. Other associated traumatic injuries should be identified by standard protocols. Large hemarthrosis can be evacuated by standard atherocentesis technique to decrease discomfort.

How To Identify and Treat Patellar Dislocation Versus Knee Dislocation

Patellar dislocation occurs when there is disarticulation of the patella bone from the patellofemoral joint. It usually occurs from low-to-moderate trauma sustained during sports or other physical activity. Risk factors for patellar dislocation include structural variants of the patella or femoral trochlea, ligamentous laxity, trauma, and connective tissue disorders. Patellar dislocations represent 3 percent of knee injuries, with a high recurrence rate ranging from 15 to 44 percent for first-time dislocations and 50 percent with a previous history of two or more dislocations.

Patellar Dislocation (Acute)

Acute patellar dislocations are common in the pediatric and adolescent populations. Adolescents and young adults, 14 to 20 years of age, account for the greatest percentage of acute traumatic patellar dislocations.

Patellar Dislocation - Peds

Flex the Hip to relax the Quads. Apply medial pressure to the lateral edge of the dislocated patella. While continuing to apply medial pressure, extend the knee.

Patellar dislocation: cylinder cast, splint or brace? An evidence-based review of the literature

Based on the best available evidence, the treatment for primary acute patellar dislocation remains controversial. A posterior splint might be the best therapeutic option because of the low redislocation rates and knee joint restrictions. However, this recommendation is based on only one small study with significant limitations.

True Knee + Patellar Dislocations

Lie the patient supine with hips flexed to relax the quadriceps. Slowly extend the knee while applying gentle and gradual medial pressure to the lateral aspect of the dislocated patella, allowing it to “pop” back into place

Resources

Emergency Medicine Guidewire

Typically occurs with trauma to an extended knee with externally rotated foot (quick pivoting in basketball, football and soccer).

Life in the Fastlane

Reduction is achieved by pushing the patellar medially with firm pressure, whilst extending the knee. First time dislocations should be splinted in above knee plaster cast and referred to the next available fracture/orthopaedic clinic Patients presenting with recurrent dislocations post reduction, can be splinted in a pressure bandage or Richards splint, until follow up can be arranged.

Physiopedia

The incidence of acute primary patellar dislocations are 2-3%. Patellar dislocations are often associated with athletes, and is most common in females in the second decade of life. Redislocation rates after conservative management are estimated between 15 and 44%.

StatPearls

Acute patellar dislocations typically occur as a result of trauma, usually a non-contact twisting injury to the knee, or from a direct blow to the medial aspect of the knee. A common mechanism is external tibial rotation with the foot fixed on the ground. There is a group of patients that suffer from chronic laxity and recurrent subluxation of their patella. The recurrence rate following a first-time dislocation can be 15-60%.