1 Introduction

There are a number of methods described to evaluate both fracture reduction and hardware placement, which include direct visualization, palpation, auscultation, assessment of crepitus during manipulation, intraoperative radiological assessment, intraoperative arthroscopy, postoperative arthroscopy, and postoperative radiological assessment ( Table 2.11.4-1 ). The difference between methods that evaluate reduction and hardware placement intraoperatively and those that do so postoperatively is an important one. Although surgeon feedback and learning from postoperative evaluation may be obtained, any adjustments in hardware placement or reduction required after a postoperative evaluation necessitate a second operative procedure.

2 Intraoperative assessment

Direct visualization of reduction and hardware placement is ideal when possible. It allows intraoperative evaluation and is simple to perform. However, effective visualization is not only approach-dependent but it also depends on the fracture and location of hardware, necessitating a decision regarding distraction or dislocation of the femoral head and/or extending the surgical dissection. This includes additional risks, especially for the blood supply to the femoral head and acetabulum.

Palpation includes intraoperative palpation of fragments and articular surfaces for incongruity or hardware and feeling for crepitus with range of motion of a joint. The latter is especially useful with digital palpation of the quadrilateral plate, which can be readily accomplished from anterior or posterior. The limitations of palpation are similar to those of visualization.

Auscultation of the hip joint has been described with [1] and without [2] the use of a stethoscope. This technique involves listening for sounds created by rough articular fragments that are poorly reduced or intraarticular hardware. This intra operative technique has been found to be highly reliable by Anglen and DiPasquale [1] who reported 100% sensitivity, specificity, and accuracy. Although they demonstrated excellent results with this technique, it is recommended that inexperienced users have practice sessions using a human anatomical specimen prior to its use in the operating room. The limitations of auscultation include determining what exactly is causing the audible sound and therefore what hardware or fracture fragment needs to be adjusted.

Intraoperative radiography includes plain x-ray images, image intensifier, and arthrography. Plain x-ray allows good visualization for the views that are obtainable but it can be difficult to obtain various images with plain film because of the problems associated with patient positioning and the x-ray machine itself. Another drawback of plain film radiology is the amount of time spent taking the film and waiting for them to be developed and returned. Ebraheim et al [3] determined that the cross table lateral and Judet iliac views were more helpful than the AP or Judet obturator view in determining screw placement. They suggested arthrography as an adjunct to plain film or image intensification if the joint space is poorly visualized.

Hip arthroscopy has been used during the initial procedure or the subsequent procedures to evaluate the joint after acetabular fractures [4–6]. This allows direct inspection of the articular surfaces without dislocation of the joint. However, the entire joint surface is not visualized. Other limitations of arthroscopy include potential iatrogenic articular surface damage, fluid extravasation, with potential compartment syndrome, and the time used in its setup and performance. Another critical issue with arthroscopy, palpation, and direct visualization is that the hardware can penetrate the subchondral bone undetected because it is not completely through the cartilage. This can result in false-negative results with these types of evaluations.

Image intensifier can be used intraoperatively and produces images immediately. More views usually can be obtained using an image intensifier because it may be draped and positioned in radiography, but it continues to improve and the time convenience and additional views obtain make this method useful. Norris et al [7] showed a 100% correlation of intraoperative image intensification and plain film and were able to obtain adequate imaging of the acetabulum 95% of the time. They described image intensifier as safe, effective, easy to use, and reliable [7]. Carmack et al [8] determined that image intensifier and computed tomography (CT) were equally accurate for determining intraarticular screw penetration. They also found that obtaining an axial image of the screw was as sensitive and specific as obtaining a tangential image when attempting to determine intraarticular placement of hardware.

Since 2002, 3-D C-arm systems are available that combine the advantages of intraoperative CT 3-D imaging with the mobility and sterility of an image intensifier. The C-arm can also be used as a regular image intensifier in its 2-D mode. Multiplanar reformations can be canvassed in seconds, so the surgeon is able to analyze the reduction ( Fig 2.11.4-1 , Fig 2.11.4-2 ) and evaluate possible intraarticular screw penetration during the procedure ( Fig 2.11.4-3 ). The software provides tools to measure angles and distances.

Kendoff et al [9] described detection of intraarticular screws, both the Iso-C 3-D and the CT scans were significantly more sensitive (96% and 96%, respectively) and specific (96% and 100%, respectively) in detecting the intraarticular position compared with 2-D image intensifier (75%; P < .05). Sensitivity of articular step-off detection was no different between the Iso-C 3-D (83%), CT (79%), and 2-D image intensifier (87%). Articular impaction was correctly identified in 79% of specimens with the Iso-C 3-D technique, while CT was accurate in 92%. The 2-D image intensifier was accurate in 62% for impactions (P < .05 vs CT) [9].

In two clinical studies [10, 11] an Iso-C 3-D scan was performed after reduction and fixation of intraarticular fractures. In 11% and 19%, respectively, the implant or reduction was revised in the same session after analyzing the scan [10, 11]. Beside the potential benefit of preventing the patient from undergoing a second operative procedure by detecting intraarticular screw penetration or a malreduction intraoperatively, the 3-D image intensifier can be used for optical navigation. Before the implant positioning, a 3-D scan is performed. The image data is then transferred to a navigation system. The navigation system will plan the implant position in the image files and display and monitor the positioning in real-time. However, the fracture reduction cannot be visualized and, in fact, has to be performed before the scan because the 3-D navigation depends on static fragment relations. Ochs et al [12] compared the optically navigated periacetabular screw placement based on a 2-D and 3-D image intensifier. Using Iso-C 3-D navigation, a perforation rate of the cortices of 7% was achieved, while using 2-D navigation the perforation rate was 20%.

However, limitations of the 3-D image intensifier are high costs, increased radiation exposure, and limited image quality and size. Besides the investment for the Iso-C 3-D, a radiolucent operation table (fully carbon) is needed [13]. In addition, the image quality is still significantly inferior to regular CT scan. The scan volume is only 12 cm³, which may be limiting for some fractures and sometimes multiple scans of the region are needed [14–16].

All intraoperative imaging techniques can be limited by poor bone quality, overlying bowel gas, obesity ( Fig 2.11.4-4 ), intraabdominal contrast from previous studies [16] in the multitrauma patient, drapes, patient position, improperly positioned lead apron, and the operating room table itself.