Fracture of the Cam Mechanism of a Posterior-Stabilized Total Knee Femoral Component: A Previously

Unrecognized Mode of Failure

by Louis S. Stryker, and David G. Lewallen

JBJS Case ConnectVolume 4(2):e51June 25, 2014

©2014 by The Journal of Bone and Joint Surgery, Inc.

Anteroposterior (left) and lateral (right) radiographs of the left total knee arthroplasty six weeks postoperatively.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

Radiography series demonstrating the ingrowth of the left total knee arthroplasty at sixty months.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

Radiography series demonstrating the ingrowth of the left total knee arthroplasty at 9.75 years, showing a loose body in the posterior aspect of the knee.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

Intraoperative photograph showing the absence of the posterior cam post.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

Intraoperative photograph following the removal of the femoral component, showing the location of the posterior cam post.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

The femoral component following removal with the broken posterior cam post.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

The end-on aspect of the broken posterior cam post (left) and the inner aspect of the lateral femoral condyle from where it had fractured (right).

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

The lateral condyle fracture area showing the initiation region (85× magnification).

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.

Anteroposterior (left) and lateral (right) radiographs of the left total knee arthroplasty at seven months postrevision.

Louis S. Stryker, and David G. Lewallen JBJS Case Connect 2014;4:e51

©2014 by The Journal of Bone and Joint Surgery, Inc.