Capacidad de Absorción de Conocimiento

Osteochondral autograft < 2 to 3 cm2 _{III or IV WB FC, T Limited tissue available,}

donor site morbidity Autologous chondrocyte

implantation

> 3 cm2 _{III or IV WB FC,}

T, P

Expensive, 2-stage Osteochondral allograft > 3 cm2 _{IV with bone loss WB FC,}

T, P

Disease transmission FC = femoral condyle; P = patella; T = tibia; WB = weight bearing.

First-line treatment for lesions smaller than 2 to 3 cm2 _{should be microfracture; if this fails,}

it should be ACI. For lesions larger than 2 to 3 cm2_{, ACI is preferred for the patellofemoral}

joint and OC allograft is preferred for high-demand patients.

Here s the Point!

Vignette 11: Hip Pain After a Motor Vehicle Collision

A 23-year-old male is the restrained driver in a motor vehicle accident and is transferred to the emergency department, where he reports right hip pain. The primary survey reveals that the patient is stable. Your physi- cal exam identifies a neutral-positioned right lower extremity with a palpable dorsalis pedis pulse and normal motor and sensory function in all distributions. Examination of the soft tissue is found to be without injury. An AP x-ray of the patient’s pelvis is shown in Figure 11-1.

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In the emergency room, to further assess the patient’s injury, Judet views are obtained (Figure 11-2) to help characterize the patient’s injury. The patient is diagnosed with a posterior acetabular wall fracture. Following appropriate resuscitation, he underwent open reduction and internal fixation (ORIF).

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Figure 11-1. AP x-ray of the

patient’s pelvis.

Figure 11-2. (A) Obturator oblique and (B) iliac oblique x-rays of the

patient’s injury.

Vignette 11: Answer

The underlying diagnosis in this case is a posterior wall acetabular fracture. The most widely used clas- sification of acetabular fractures is that of Letournel and Judet (Table 11-1).35 _{This system divides fractures}

of the acetabulum into 5 elementary and 5 associated patterns. The elementary patterns are defined as those that separate all or part of a single column of the acetabulum. The anterior and posterior column fractures separate the entire column from the intact innominate bone, whereas the anterior and posterior wall frac- tures separate only a portion of the column’s articular surface. The integrity of the obturator foramen and ischiopubic ramus may aid the surgeon in making this distinction. Also included in the elementary patterns are transverse acetabular fractures that disrupt the anterior and posterior column.

Radiographic assessment of acetabular fractures includes AP, iliac oblique, obturator oblique, inlet, and outlet images to characterize the fracture pattern and evaluate for joint displacement; the inlet and outlet views allow the surgeon to assess for pelvic injuries that may affect acetabular injury management and are not routinely obtained. CT scans, particularly the axial sections, have a distinct advantage in showing the site and degree of displacement of fractures, their orientation in these dimensions, the relationship of small fragments, the amount of articular surface involvement (beware of the marginal impaction—crushing of the posterior acetabular articular), and whether loose bodies reside within the joint. Three-dimensional (3D) reconstructions may help to better understand the fracture pattern and delineate any rotational deformity.

Upon initial evaluation, a careful and thorough examination documenting complete neurologic assess- ment of the patient (including rectal exam, reflexes, and full motor and sensation testing) and lower extrem- ity soft tissue integrity (beware the dreaded Morel-Lavallée lesion—a closed degloving injury, with the skin and subcutaneous tissues being stripped off of the underlying fascia, allowing for a blood-filled cavity to form) in the trochanteric and gluteal regions, and resting position of the lower extremity should be com- pleted. The sciatic nerve, which is injured in up to 20% of acetabular fractures affecting the posterior wall or column, should be carefully examined in motor and sensory distributions. Because the peroneal division is at risk for stretch injury, foot dorsiflexion and eversion must be tested.

In general, acetabular fractures occur as a result of a severe force to the femur that is transmitted through the femoral neck, resulting in femoral head impaction against the acetabulum; the magnitude and force vector impacting the acetabulum determines the resultant fracture pattern. Commonly, in the setting of a head-on motor vehicle collision, the knee strikes the dashboard, resulting in a proximally directed force that potentially results in acetabular injury. By virtue of the mechanism, the potential for patella fracture, chondral injuries, knee ligamentous injuries, and femoral neck fracture should also be kept in mind when evaluating any patient with an acetabular fracture resulting from a dashboard-type injury. The pelvic CT used to assess the acetabular injury often extends to the proximal femur; these images should be carefully reviewed to help identify subtle fractures of the femoral neck prior to proceeding to the operating suite.

There are several known complications. The primary complication following acetabular fracture is post- traumatic arthrosis. Long-term studies demonstrate that articular reductions within 1 mm of displacement

Table 11-1.

LETOURNEL ACETABULAR CLASSIFICATION