Acetabular fractures revisited: a new CT-based classification.

The objective of this investigation is to provide a new CT-based classification of acetabular fractures. The axial CT scans of 112 randomly selected acetabular fracture patients admitted to a Level 1 trauma center between January 1998 and December 2000 were analyzed by an experienced orthopedic trauma surgeon and two experienced emergency radiologists. When available, 3D reformatted images were analyzed as well. The fracture pattern for each acetabular fracture with respect to column(s) wall(s) and extension superiorly and/or inferiorly from the acetabulum, when present, was recorded. Fracture comminution was not a defining characteristic. Analysis of the acetabular fracture patterns showed that each fracture fell into one of four broad categories: Category 0--wall only; Category 1--single column; Category 2--both columns, with extension subcategories of (A) no extension, (B) superior extension only, (C) inferior extension only, and (D) both superior and inferior extension; and Category 3--the "floating" acetabulum. The axial CT display of acetabular fracture patterns provides a basis for a classification of acetabular fractures that is simple, unambiguous, readily understood by both radiologists and orthopedic surgeons, and provides clear direction for both diagnosis and surgical treatment planning. Category and subcategory fracture specificity creates a mechanism for intra- and interdepartmental postoperative assessment of any of the individual acetabular fracture types.

Acetabular fractures revisited: part 1, redefinition of the Letournel anterior column.

OBJECTIVE: The objective of part 1 of this study is to redefine the Letournel anterior column on the basis of developmental and adult pelvic skeletal anatomy. MATERIALS AND METHODS: The axial CT scans of 112 randomly selected patients with acetabular fracture or fracture-dislocations admitted to a level I trauma center between January 1998 and December 2000 were analyzed by an experienced orthopedic trauma surgeon and two experienced emergency radiologists. When available, 3D reformatted images were analyzed as well. The discrepancy between the Letournel definition of the anterior and posterior columns became readily apparent. Standard text books of anatomy and surgical anatomy were referenced relative to the embryologic and adult components of the acetabulum. RESULTS: The anterior column is redefined with its superior border being the anatomic arcuate and iliopectineal lines, thereby coinciding with the superior border (arcuate line) of the Letournel posterior column. CONCLUSION: Redefinition of the anterior column eliminates diagnostic ambiguity of the Letournel elementary anterior column fracture as well as the Letournel associated anterior column or wall with hemitransverse fracture. The redefined anterior column is integral to the CT-based classification described in part 2 of our study.

Acetabular fractures revisited: part 2, a new CT-based classification.

OBJECTIVE: The objective of this investigation was to provide a new CT-based classification of acetabular fractures. MATERIALS AND METHODS: The axial CT scans of 112 randomly selected acetabular fractures in patients admitted to a level 1 trauma center between January 1998 and December 2000 were analyzed by an experienced orthopedic trauma surgeon and two experienced emergency radiologists. When available, 3D reformatted images were analyzed as well. The fracture pattern for each acetabular fracture, with respect to column walls and extension beyond the acetabulum, when present, was recorded. Fracture comminution was not a defining characteristic. RESULTS: Analysis of the 112 acetabular fracture patterns showed that each fracture fell into one of four broad categories. Category 0 included wall fractures only. Category I included acetabular fractures limited to a single (anterior or posterior) column. Category II fractures included those involving both the anterior and posterior columns; category II fractures were further subdivided into those with no fracture extension beyond the acetabulum, those with superior or inferior extension, and those with both superior and inferior extensions beyond the acetabulum. Category III fractures included only the "floating" acetabulum, which is defined as an acetabular fracture in which the acetabulum is separated from the axial skeleton both anteriorly and posteriorly. CONCLUSION: The axial CT display of acetabular fracture patterns provides a basis for a classification of acetabular fractures that is simple, unambiguous, readily understood by both radiologists and orthopedic surgeons and provides clear direction for both diagnosis and surgical treatment planning. Category and subcategory fracture specificity creates a mechanism for intra- and interdepartmental postoperative assessment of any of the individual acetabular fracture types.

Mechanical testing of small fracture implants for comparison of insertion and failure torques.

INTRODUCTION: Small fracture screws are among the most commonly used implants in the field of orthopedic surgery. The goal of this study was to compare the insertion and failure torques of three screw types: cortical, partially threaded cancellous, and fully threaded cancellous from three manufacturers: Zimmer, Richards, and Synthes. MATERIALS AND METHODS: Each type of screw was subjected to biomechanical tests to determine the insertion ( n=6/group) and failure ( n=10/group) torques. RESULTS: Two-factor ANOVA tests were run to determine whether the insertion or failure torques were different for the different screw types and manufacturers. In the case of insertion torques, neither the screw nor the manufacturer had any significant effect. In the case of failure torque, significant differences were found based on both the screw type and the manufacturer, with the cortical screws manufactured by Zimmer being the strongest. Although there were strength differences, the most important comparison clinically is between the failure torque and the insertion torque of each screw. In all cases, the failure torques were approximately 20 times larger than the insertion torques, and therefore no failures should occur if only torsional loads are applied during insertion. This comparison shows that factors other than screw strength and manufacturing processes may be involved in cases of screw failure during insertion. CONCLUSION: All three screw types from all three manufacturers appear to be mechanically reliable, with the proper insertion to failure torque ratio. The surgeon's choice of implant should be based on other considerations.