Fractures of the Patella

Fractures of the patella occur from a direct blow such as with the knee striking a car dashboard in an MVA, a fall on the flexed knee, or forceful contraction of the quadriceps muscles, which can occur with falling or stumbling. Fractures may be transverse, comminuted, or of the avulsion type, when the quadriceps or patellar tendon pulls off a small portion of the patella ( Fig.,,,266-1).

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FIG. 266-1. Classification of patellar fractures. (From Hohl M, Johnson EE, Wiss DA. Fractures of the knee, in Rockwood CA Jr, Green DP, Bucholz RW (eds): Fractures in Adults, 3d ed, vol. 2. Philadelphia, Lippincott, 1991, p. 1765. Used with permission.)

Transverse fractures of the patella are most common, followed by stellate and comminuted fractures.7 Patients with nondisplaced fractures may be ambulatory. Physical examination reveals focal patellar tenderness, swelling, and effusion. It is imperative that the integrity of the extensor mechanism of the knee be checked by having the patient perform a straight-leg raise against gravity. Transverse fractures are more likely to be displaced and have a disrupted extensor mechanism. Differential diagnosis of patellar fractures radiographically includes bipartite patella. This condition involves the superior lateral corner of the patella, is typically bilateral, and is differentiated from fracture by its smooth cortical margins.

A nondisplaced fracture of the patella with an intact extensor mechanism is initially treated in the emergency department with a knee immobilizer, ice, elevation, and nonsteroidal anti-inflammatory drugs and/or opioid analgesics. Such fractures are generally treated in a long leg cast for a total of six weeks of immobilization. 7 During this period the patient should be encouraged to walk on crutches initially, with partial weight-bearing progressing to full weight-bearing as tolerated. Fractures that are displaced greater than 3 mm, or that are associated with the disruption of the extensor mechanism, require early referral to orthopedics for open reduction and internal fixation.7 This generally consists of tension-band wiring of the patella and suturing of the retinaculum. Severely comminuted fractures may be treated surgically by removal of smaller fragments (or all fragments if they are small) and suturing of the quadriceps and patellar tendons. All open fractures must be debrided and irrigated by orthopedics in the operating room and antistaphylococcal antibiotics should be administered. The overall prognosis for patellar fractures is good. 7

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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