David M. Kahler

Distal Femoral Fractures: Current Concepts

Abstract The diversity of surgical options for the management of distal femoral fractures reflects the challenges inherent in these injuries. These fractures are frequently comminuted and intra‐articular, and they often involve osteoporotic bone, which makes it difficult to reduce and hold them while maintaining joint function and overall limb alignment. Surgery has become the standard of care for displaced fractures and for patients who must obtain rapid return of knee function. The goal of surgical management is to promote early knee motion while restoring the articular surface, maintaining limb length and alignment, and preserving the soft‐tissue envelope with a durable fixation that allows functional recovery during bone healing. A variety of surgical exposures, techniques, and implants has been developed to meet these objectives, including intramedullary nailing, screw fixation, and periarticular locked plating, possibly augmented with bone fillers. Recognition of the indications and applications of the principles of modern implants and techniques is fundamental in achieving optimal outcomes.

Screw placement for acetabular fractures: which navigation modality (2-dimensional vs. 3-dimensional) should be used? An experimental study.

Objectives: Screw navigation techniques with different image guidance [2-dimensional (2D) vs. 3-dimensional (3D) fluoroscopy] were evaluated for acetabular fracture surgery. Methods: Two-dimensional and 3D navigation images were analyzed for visualization of different osseous corridors: supra-acetabular, anterior column, posterior column, and infra-acetabular. Forty guide wires per group were placed in synthetic pelvis with a prefabricated soft tissue envelope (10 per group) using a 2D or 3D fluoroscopic navigation procedure. Duration of the single steps for each procedure and of cumulative fluoroscopy time was measured. The accuracy of guide wire placement was evaluated visually and in 3D cone-beam scans. Results: The overall procedure time per pelvis was significantly reduced in the 3D group compared with the 2D group [mean ± standard error (SE) (minutes): 50.11 ± 1.38 vs. 63.42 ± 2.32; P < 0.0001]. A trend to reduction in image acquisition time [mean ± SE (minutes): 12.37 ± 1.34 vs. 15.43 ± 1.03; P = not significant] and significant increase in the cumulative fluoroscopy time [mean ± SE (seconds): 64 ± 9 vs. 13 ± 1.3; P < 0.0001) was measured in the 3D compared with the 2D group, caused by the 3D scan. Intra-articular misplacements were not observed in both the groups, but an increased accuracy could be achieved using the 3D image–based navigation procedure (perfect placement: 37 vs. 29; secure placement: 2 vs. 7; misplacement: 1 vs. 4). Conclusions: Both navigation procedures securely prevent an intra-articular penetration during drilling, but the 3D image–based navigation procedure increases the overall accuracy compared with the 2D image–based navigation technique (misplacement rates of 2.5% vs. 10%). Especially, in very narrow corridors (as the infra-acetabular screw path), the use of 3D navigation should be preferred.

Navigated Long-Bone Fracture Reduction

The first computer-assisted orthopaedic trauma procedures were limited to navigated drill-guide applications, in which the computer was used to predict the trajectory of the drill guide relative to stored radiographic images. By 2003, software for fracture reduction was commercially available. The ability to perform a minimally invasive fracture reduction with the aid of stored images, combined with navigated insertion of internal fixation, has long been considered the highest achievement in image-guided fracture surgery. It is now possible to apply computer-assisted techniques to all fractures that have traditionally been treated with the aid of intraoperative fluoroscopic control. Less-invasive fixation of long-bone fractures is often complicated by malrotation or shortening of the injured extremity, sometimes requiring reoperation. Recent developments in computer-assisted surgery now allow the orthopaedic surgeon to precisely match the anatomy of the injured extremity to that of the uninjured limb with respect to length and rotational alignment. This is particularly important in comminuted fractures, for which there are no anatomic clues to guide accurate reduction, and in the correction of malreduced fractures. Although computer-assisted technology is now readily available, it has not yet found widespread acceptance in the orthopaedic trauma community. New software workflows (i.e., the step-by-step progression through various screens in the software program during a computer-guided procedure) specific to individual procedures and implants may hasten adoption of these techniques.

Fluoro-Free navigated retrograde drilling of osteochondral lesions

PurposeRetrograde drilling of osteochondral lesions (OCLs) is a recommended, but demanding operative approach for revascularization of lesions in stage 1–3 according to Berndt and Harty after failed conservative treatment. The gold standard of intraoperative driller guidance is fluoroscopic control. Limitations are a 2D visualization of a 3D procedure and sometimes limited view of the OCL in fluoroscopy, leading to increased radiation exposure. A new image-free navigation procedure was evaluated for practicability and precision in first clinical applications.MethodsIn a period of 7xa0months, retrograde drillings were performed in eight patients (3x femoral condyle, 5x talus) using the new Fluoro-Free navigation procedure without rigidly fixed reference bases.ResultsIn total, 29 retrograde drillings were performed without any technical problem. The overall mean operating time was 82.1xa0±xa029.3xa0min (34.6xa0±xa06.4xa0min for the standard arthroscopy and 11.2xa0±xa01.2xa0min per drill). Twenty-seven of 29 drillings hit the target with a 100% first-pass accuracy. Two complications during drilling (one navigation specific and one navigation independent) were observed.ConclusionThe paper describes the promising first clinical applications of a new Fluoro-Free navigation procedure for the retrograde drilling of OCLs determined by arthroscopy. The benefit of that navigated drillings with a high rate of first-pass accuracy and no need for radiation exposure in contrast to standard techniques is highlighted.

Percutaneous Screw Insertion for Acetabular and Sacral Fractures

Summary Orthopaedic trauma has long been identified as a potential impact area for the new field of image-guided surgery. Early experience with three-dimensional (3-D) computed tomography-based image-guided surgery was promising, but this particular technique was limited by the inability to update the 3-D computer model in the operating room after fracture reduction maneuvers or implant placement. Virtual fluoroscopy, or fluoroscopic navigation, became available in 1999 and has proven to be a more versatile technology for fracture management. Fluoroscopic navigation systems allow the surgeon to store multiple intraoperative fluoroscopic images on a computer workstation; the position of special optically tracked surgical instruments or implants can then be virtually overlaid onto the stored images in multiple planes during implant placement. The ability to update images after fracture manipulation has now expanded the application of computer-assisted surgery to any procedure that has traditionally relied on intraoperative C-arm use. In selected pelvic trauma applications, this technology has been shown to decrease both operative time and intraoperative radiation exposure. This review covers the current use of surgical navigation in implant placement around the pelvis.

A comparison of optical and electromagnetic computer-assisted navigation systems for fluoroscopic targeting.

Objectives: Freehand targeting using fluoroscopic guidance is routine for placement of interlocking screws associated with intramedullary nailing and for insertion of screws for reconstruction of pelvic and acetabular injuries. New technologies that use fluoroscopy with the assistance of computer guidance have the potential to improve accuracy and reduce radiation exposure to patient and surgeon. We sought to compare 2 fluoroscopic navigation tracking technologies, optical and electromagnetic versus standard freehand fluoroscopic targeting in a standardized model. Intervention: Three experienced orthopaedic trauma surgeons placed 3.2-mm guide pins through test foam blocks that simulate cancellous bone. The entry site for each pin was within a circular (18-mm) entry zone. On the opposite surface of the test block (130-mm across), the target was a 1-mm-diameter radioopaque spherical ball marker. Each surgeon placed 10 pins using freehand targeting (control group) navigation using Medtronic iON StealthStation (Optical A), navigation using BrainLAB VectorVision (Optical B), or navigation using GE Medical Systems InstaTrak 3500 system (EM). Outcome Measurements: Data were collected for accuracy (the distance from the exit site of the guidewire to the target spherical ball marker), fluoroscopy time (seconds), and total number of individual fluoroscopy images taken. Results: The 2 optical systems and the electromagnetic system provided significantly improved accuracy compared to freehand technique. The average distance from the target was significantly (3.5 times) greater for controls (7.1 mm) than for each of the navigated systems (Optical A = 2.1 mm, Optical B = 1.9 mm EM = 2.4 mm; P < .05). Accuracy was similar for the 3 navigated systems, (P > 0.05). The ability to place guidewires in a 5-mm safe zone surrounding the target sphere was also significantly improved with the optical systems and the EM system (99% of wires in the safe zone) compared to controls (47% in the safe zone) (P < 0.002). Safe zone placement was similar among the 3 navigated systems (P > 0.05). Fluoroscopy time (seconds) and number of fluoroscopy images were similar among the three navigated groups (P > 0.05). Each of these parameters was significantly less when using the computer-guided systems than for freehand-unguided insertion (P < 0.01). Conclusions: Both optical and electromagnetic computer-assisted guidance systems have the potential to improve accuracy and reduce radiation use for freehand fluoroscopic targeting in orthopaedic surgery.

Three-dimensional navigation is more accurate than two-dimensional navigation or conventional fluoroscopy for percutaneous sacroiliac screw fixation in the dysmorphic sacrum: a randomized multicenter study.

Objectives: To evaluate the accuracy of computer-assisted sacral screw fixation compared with conventional techniques in the dysmorphic versus normal sacrum. Design: Review of a previous study database. Setting: Database of a multinational study with 9 participating trauma centers. Patients: The reviewed group included 130 patients, 72 from the navigated group and 58 from the conventional group. Of these, 109 were in the nondysmorphic group and 21 in the dysmorphic group. Intervention: Placement of sacroiliac (SI) screws was performed using standard fluoroscopy for the conventional group and BrainLAB navigation software with either 2-dimensional or 3-dimensional (3D) navigation for the navigated group. Main Outcome Measurements: Accuracy of SI screw placement by 2-dimensional and 3D navigation versus conventional fluoroscopy in dysmorphic and nondysmorphic patients, as evaluated by 6 observers using postoperative computerized tomography imaging at least 1 year after initial surgery. Intraobserver agreement was also evaluated. Results: There were 11.9% (13/109) of patients with misplaced screws in the nondysmorphic group and 28.6% (6/21) of patients with misplaced screws in the dysmorphic group, none of which were in the 3D navigation group. Raw agreement between the 6 observers regarding misplaced screws was 32%. However, the percent overall agreement was 69.0% (kappa = 0.38, P < 0.05). Conclusions: The use of 3D navigation to improve intraoperative imaging for accurate insertion of SI screws is magnified in the dysmorphic proximal sacral segment. We recommend the use of 3D navigation, where available, for insertion of SI screws in patients with normal and dysmorphic proximal sacral segments. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Computer-assisted percutaneous fixation of acetabular fractures and pelvic ring disruptions

The complex anatomy of the pelvis contains many vital anatomic structures. In the past, this anatomic complexity has necessitated wide surgical exposures for internal fixation of traumatic disruptions of the pelvis and acetabulum. The availability of computer-assisted surgical technology has made it possible to decrease the invasiveness of internal fixation procedures about the pelvis. Optically tracked surgical instruments can be used to pass cannulated screws percutaneously according to precise preoperative plans, using patient-specific anatomy derived from computed tomography scans. This technique has broad potential for both pure percutaneous procedures and open procedures as well.