Characterization of acetabular fractures can be difficult because of the complex acetabular anatomy and the many fracture patterns.
The five most common acetabular fractures are: bi-column,
T-shaped,
transverse,
transverse with posterior wall,
and isolated posterior wall.
1 Acetabular bi-column fractures are challenging articular injuries that usually require operative treatment.2
Accurate classification of acetabular fractures is important for determining the proper surgical treatment.3 Because of the complex acetabular anatomy,
various classification schemes have been suggested,
but the Judet-Letournel classification system (Fig. 1) remains the most widely accepted.
4-7
The addition of CT with multiplanar reconstruction and 3D surface rendering is helpful in understanding and classifying acetabular fractures.
8,9
Percutaneous fixation of fractures involving the anterior and posterior walls of the acetabulum (Fig. 2),
although a relatively new concept in South Africa,
has been described previously in the literature since 1997.10 Percutaneous fixation of the sacro-iliac joint has long been considered the gold standard of treatment of for posterior element instability of the pelvis.
11,12 Currently the fixation of unstable fractures of the acetabulum with percutaneous screws introduced through small incisions is gaining more attention and popularity.
13,14 These procedures are less invasive as compared to open fixation and are more beneficial to the patient in terms of early mobilisation (especially in the elderly).
11
The major advantage is the immediate stability obtained which leads to early full weight-bearing mobilisation.
Other important advantages over formal open procedures are the decreased operative morbidity,
blood loss and time to perform the procedure.
Wound healing,
infection and blood loss are all complications that are more attributable to the open procedure than to the actual fractures themselves.
11
Where fractures are amenable and/ or patients have contra-indications to major procedures,
percutaneous procedures should ideally be used.
In the review study published by Giannoudis et al,
it was found in the early results of many studies that patients enjoyed a shorter hospital stay and decreased morbidity when treated with percutaneous techniques for acetabular column fractures.
11
Average sizes of the columns in the South African population,
are not readily available,
as not much investigation has been performed for the selection of appropriate length of screws for use in local practice.
Dedicated instrumentation is not currently available in South Africa and logistics and costs involved in pre-ordering and obtaining the correct screws from abroad leaves little room for error.
Incorrect sizing can lead to cortical breach when traversing the osseous channels/ columns that can lead to catastrophic vascular damage.
Therefore,
the correct selection of a screw with a safe diameter is vital for patient safety.
Comparisons of American and Chinese populations vary widely with regard to size,
with additional significant differences between male and female populations.
13,15 Complicating the process are also the varying recommendations that have been made regarding the safe diameter of screws to be used in the fixation.
14-18
Close co-operation between trauma surgeons,
orthopaedic surgeons and radiologists is mandatory for appropriate patient selection and planning of the procedure.
19
The purpose of our study is to determine appropriate lengths of screws for external percutaneous fixation of the pelvis which is required for the South African population for this important procedure to gain acceptability.
The study specifically aims to measure the normal pelvis in a typical cross-section of the South African population and then use sub-group analysis to guide screw selection for a safe procedure in the varying ethnic groups in the country.
Therefore the main aim is to describe the measurements obtained of the lengths and diameters of the anterior and posterior acetabular columns using CT 3D volume reconstructions of the normal pelvis (Fig. 3) ,
in the South African population and to make recommendations for selecting percutaneous fixation screws to treat fractures of the acetabular columns.