Three-dimensional imaging of acetabular trauma

Intraoperative Imaging Challenges During Pelvic Ring Disruptions and Acetabular Fracture Surgery

Achieving high-quality intraoperative imaging is crucial for successful pelvic ring and acetabular fracture surgery, yet it remains clinically challenging. Due to the complex anatomy of the pelvic ring and acetabulum, it is necessary to obtain multiple images oriented in different planes to reliably confirm reduction accuracy and implant positioning. Intraoperative image quality can be compromised by factors such as patient body habitus, bowel gas, abdominal packing, contrast dye, and nonstandardized language between surgeon and radiology technician. This article reviews common intraoperative imaging challenges encountered during pelvic ring and acetabular fracture surgery, while providing practical and evidence-based solutions and prevention strategies.

3D printing of implants for patient-specific acetabular fracture fixation: an experimental study

PURPOSE

To test the effect of 3D printed implants, designed according to surgeon's individual plan, on the accuracy of reduction of an acetabular fracture model.

METHODS

Seven identical standardized plastic bone models of an anterior column/posterior hemi-transverse acetabular fracture were used. A CT of one plastic fracture model was made. Using preoperative planning software, three surgeons independently planned the reduction and fixation procedure and designed implants and drill guides. The designed implants and guides were then 3D printed. Each surgeon first executed his plan using his 3D printed plates and guides on one fracture model and then performed another procedure on an identical model with standard implants and instrumentation. Displacement of the fragments at the weight-bearing fracture lines in the acetabulum was measured after fixation. Linear mixed effect models were used to evaluate the effect of different solutions to the same fracture pattern.

RESULTS

Mean (SD) displacement of the fracture line between the ischium and stable fragment was 1.1 (0.9) mm for the standard implant and 0.8 (0.6) mm for the 3D printed implant, while the displacements of the fracture line between the stable fragment and anterior column were 0.6 (0.6) and 0.3 (0.3) for the standard and 3D printed methods, respectively (p < 0.001). Mean (SD) fracture line step-off at any fracture line for the standard implant was 1.2 (0.9) mm and 0.4 (0.4) mm for the 3D printed implant (p = 0.022).

CONCLUSIONS

Patient-specific 3D printed plates and drill guides may facilitate retaining accurate reduction and fixation of select acetabular fracture patterns.

Acetabular fractures: what radiologists should know and how 3D CT can aid classification

Correct recognition, description, and classification of acetabular fractures is essential for efficient patient triage and treatment. Acetabular fractures may result from high-energy trauma or low-energy trauma in the elderly. The most widely used acetabular fracture classification system among radiologists and orthopedic surgeons is the system of Judet and Letournel, which includes five elementary (or elemental) and five associated fractures. The elementary fractures are anterior wall, posterior wall, anterior column, posterior column, and transverse. The associated fractures are all combinations or partial combinations of the elementary fractures and include transverse with posterior wall, T-shaped, associated both column, anterior column or wall with posterior hemitransverse, and posterior column with posterior wall. The most unique fracture is the associated both column fracture, which completely dissociates the acetabular articular surface from the sciatic buttress. Accurate categorization of acetabular fractures is challenging because of the complex three-dimensional (3D) anatomy of the pelvis, the rarity of certain acetabular fracture variants, and confusing nomenclature. Comparing a 3D image of the fractured acetabulum with a standard diagram containing the 10 Judet and Letournel categories of acetabular fracture and using a flowchart algorithm are effective ways of arriving at the correct fracture classification. Online supplemental material is available for this article.

An interactive surgical planning tool for acetabular fractures: initial results

Background

Acetabular fractures still are among the most challenging fractures to treat because of complex anatomy, involved surgical access to fracture sites and the relatively low incidence of these lesions. Proper evaluation and surgical planning is necessary to achieve anatomic reduction of the articular surface and stable fixation of the pelvic ring. The goal of this study was to test the feasibility of preoperative surgical planning in acetabular fractures using a new prototype planning tool based on an interactive virtual reality-style environment.

Methods

7 patients (5 male and 2 female; median age 53 y (25 to 92 y)) with an acetabular fracture were prospectively included. Exclusion criterions were simple wall fractures, cases with anticipated surgical dislocation of the femoral head for joint debridement and accurate fracture reduction. According to the Letournel classification 4 cases had two column fractures, 2 cases had anterior column fractures and 1 case had a T-shaped fracture including a posterior wall fracture.

The workflow included following steps: (1) Formation of a patient-specific bone model from preoperative computed tomography scans, (2) interactive virtual fracture reduction with visuo-haptic feedback, (3) virtual fracture fixation using common osteosynthesis implants and (4) measurement of implant position relative to landmarks. The surgeon manually contoured osteosynthesis plates preoperatively according to the virtually defined deformation. Screenshots including all measurements for the OR were available.

The tool was validated comparing the preoperative planning and postoperative results by 3D-superimposition.

Results

Preoperative planning was feasible in all cases. In 6 of 7 cases superimposition of preoperative planning and postoperative follow-up CT showed a good to excellent correlation. In one case part of the procedure had to be changed due to impossibility of fracture reduction from an ilioinguinal approach. In 3 cases with osteopenic bone patient-specific prebent fixation plates were helpful in guiding fracture reduction. Additionally, anatomical landmark based measurements were helpful for intraoperative navigation.

Conclusion

The presented prototype planning tool for pelvic surgery was successfully integrated in a clinical workflow to improve patient-specific preoperative planning, giving visual and haptic information about the injury and allowing a patient-specific adaptation of osteosynthesis implants to the virtually reduced pelvis.

Imaging of the acetabulum in the era of multidetector computed tomography

Acetabular fractures are often complex injuries and the result of high-energy trauma with associated injuries. Understanding and classification of these rare injuries using radiography can be difficult and are much facilitated by the addition of computed tomography (CT). The purpose of this paper is to briefly review some of the underlying physical principles and technical factors for multidetector CT (MDCT) and to describe its use and imaging findings in the evaluation of acetabular fractures. Using MDCT with two-dimensional multiplanar reformatted (MPR) images and three-dimensional volume rendered images, the supplemental oblique radiographic Judet views can be omitted. MDCT is now an indispensable tool in preoperative imaging of acetabular fractures and also in postoperative imaging in complicated cases. Not only is MDCT excellent for a general overview but also for detailed imaging of fracture extent, joint congruency, step-offs or gaps in the joint surface, and entrapped osteochondral fragments.

Three-dimensional computer analysis of complex acetabular insufficiency

Fourteen patients with acetabular dysplasia were studied by using three-dimensional computed tomography (CT) reconstructions before pelvic osteotomies. Computer manipulation of the data allowed a preoperative visual assessment of acetabular shape, assessment of potential congruency between the femoral head and acetabulum by using a mathematical best-fit sphere, and measurement of surface contact distances that depict joint coverage and relate to concentration of weight-bearing forces. Preoperative evaluation of the three-dimensional images for these 14 patients allowed improved understanding of their abnormal anatomy and better surgical planning.