Roof Arc Measurements Acetabular Fractures

2 mm fine cuts on axial view.

Roof arc measurements acetabular fractures.

For patients with acetabular fractures the extent to which a fracture involves the weight bearing dome has been estimated with the roof arc measurement obtained on radiographs and computed tomographic ct studies. Average medial anterior and posterior acetabular roof arc angles of the absawba of 94 normal acetabulum were 39 09 7 41 42 49 8 15 and 55 26 10 08 degrees respectively. Defined as an intact subchonral ring in the superior 10 mm of the acetabulum 2 mm incongruity in the articular segment is considered unstable. In acetabular fracture a medial roof arc angle less than 46 degrees an anterior roof arc angle less than 52 degrees or posterior roof arc angle less than 61 degrees is considered to be involved in a weight bearing area.

Determine the amount of intact acetabular dome and evaluate the need for surgery. Assess stability of the weight bearing dome based on the exiting fracture line. Computerized tomography ct of the superior 10 mm of the acetabular articular surface evaluates the area equivalent to roof arc measurements of 45. It is generally accepted that intra operative roof arc angles of 45 or more represents a satisfactory restitution of the weight bearing portion of the acetabulum cavity 12.

In acetabular fracture a medial roof arc angle less than 46 an anterior roof arc angle less than 52 or posterior roof arc angle less than 61 is considered to be involved in a weight bearing area. The technique of roof arc measurements was developed to identify the extent of superior acetabulum left intact after fracture. The criteria to treat acetabular fractures operatively versus nonoperatively continue to evolve. With peekmed a powerful 3d pre operative.

The medial roof arc angle was 46 6 3 degrees anterior roof arc angle was 52 7 0 degrees and posterior roof arc angle was 62 degrees 8 5 degrees. We present the method for measuring the roof arc on radiographs and estimating this arc on ct scans. However when there is an associated posterior wall fracture the radiographic roof arc measurement cannot be used at the preoperative period. Less than 39 42 and 55 of medial anterior and posterior acetabular roof arc angles involve absawba of the femoral head.