Dislocated patella overview

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Grace M. Gibson

Overview

Luxating patella is a condition in which the patella, or kneecap, dislocates or moves out of its normal location. The luxation is usually medial, but can be lateral.

Causes

It can be caused by some form of blunt trauma, or may be a congenital defect. In congenital cases, it is usually bilateral.

Natural History, Complications and Prognosis

Osteoarthritis can develop secondarily.

Diagnosis

History and Symptoms

Symptoms can range from none to severe pain.

Physical Examination

Diagnosis is made through palpation of the knee. The patient can do the patella tracking assessment by making a single leg squat and standing, or, lying on his or her back with knee extended from flexed position. A patella that slips medially on early flexion is called the J sign, and indicates imbalance between the VMO and lateral structures.^[1]

X Ray

X-rays are necessary in some cases.

Treatment

Medical Therapy

Supplements like glucosamine and NSAIDs can be used to keep the knee strong.

Surgery

Grades III and IV, as well as most grade II cases, require surgery to correct, if the patient has difficulty walking. The surgery involves a sulcoplasty, a deepening of the trochlear sulcus that the patella sits in.

References

↑ Family Practice Notebook > Patella Tracking Assessment by Scott Moses, last revised before 5/10/08

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[1] Family Practice Notebook > Patella Tracking Assessment by Scott Moses, last revised before 5/10/08

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