Detection of articular perforations of the proximal humerus fracture using a mobile 3D image intensifier - a cadaver study.

BACKGROUND: The purpose of this study was to investigate the accuracy of perforation detection with multiplanar reconstructions using a mobile 3D image intensifier. METHODS: In 12 paired human humeri, K-wires perforating the subchondral bone and placed just below the cartilage level were directed toward five specific regions in the humeral head. Image acquisition was initiated by a fluoroscopy scan. Within a range of 90°, 45° external rotation (ER) and 45° internal rotation (IR). The number and percentage of detected perforating screws were grouped and analyzed. Furthermore, the fluoroscopic images were converted into multiplanar CT-like reconstructions. Each K-wire perforation was characterized as "detected" or "not detected". RESULTS: In the series of fluoroscopy images in the standard neutral position at 30° internal rotation, and 30° external rotation, the perforations of all K-wires (n = 56) were detected. Twenty-nine (51.8%) of them were detected in one AP view, 22 (39.3%) in two AP views, and five (8.9%) in three AP views. All K-wire perforations (100%, n = 56) were detected in multiplanar reconstructions. CONCLUSION: In order to reveal all of the intraoperative and postoperative screw perforations in a "five screw configuration", conventional AP images should be established in both the neutral positions (0°), at 30° internal rotation and 30° external rotation. Alternatively, the intraoperative 3D scan with multiplanar reconstructions enables a 100% rate of detection of the screw perforations.

Detection of primary screw perforation in locking plate osteosynthesis of proximal humerus fracture by intra-operative 3D fluoroscopy.

PURPOSE: The purpose of this study was to identify the rate of primary screw perforations after osteosynthesis of proximal humerus fractures with intra-operative 3D fluoroscopy and to analyse the rate of secondary screw perforations as well as complications, outcome, and revision surgeries after a minimum of 12 months. MATERIALS AND METHODS: Thirty-three patients (20 female, 13 male, median age 67 years, range 35-85 years) with displaced proximal humerus fractures were included. After reduction and fixation, an intra-operative 3D fluoroscopy was performed to evaluate primary screw perforations (PS) and screws with "near perforation" (nPS). These screws were changed intra-operatively. Patients were followed-up for a minimum of 12 months. Clinical and radiological parameters, such as secondary screw perforation, secondary loss of reduction, or functional outcome, were investigated. RESULTS: In six patients (18.2%), humeral head screws were changed due to primary PS (n = 2) or nPS (n = 4) after the intra-operative 3D fluoroscopy. Follow-up revealed an adapted constant score (%CMS) of 76.2% after a mean follow-up of 17.7 months. Two secondary screw perforations were observed (6%). Loss of reduction was observed in eight patients (24.2%). CONCLUSION: The intra-operative 3D reveals a high rate of primary screw perforations or near perforations. Immediate change of these screws may lead to a lower rate of secondary screw perforations and, therefore, reduce post-operative complications.

Image-free navigated coracoclavicular drilling for the repair of acromioclavicular joint dislocation: a cadaver study.

BACKGROUND: Reconstruction of the coracoclavicular ligament functions to restore anatomic alignment of the clavicle and may improve biomechanical function and clinical outcomes. Improper placement of the coracoclavicular tunnel may inherently weaken the coracoid. The purpose of this study was to evaluate the feasibility and accuracy of navigated image-free placement of K-wires for coracoclavicular tunnel position in comparison to conventional drill guide-based placement. MATERIALS AND METHODS: Eight human shoulder specimens were assigned for conventional technique with a coracoclavicular guide device (group CP) and the paired contralateral side for the navigated procedure (group NP) with an optoelectronic system with a fluoro-free software module. First-pass accuracy (%) and the K-wire trajectory (lateral-center orientation (LC), center-center (CC) orientation and medial-center orientation (MC) were measured. RESULTS: In all navigated K-wires a 100 % first-pass accuracy was observed. In three of the eight (37.5 %) specimens of the drill guide-based group, drilling had to be repeated. One of them had to be repeated twice, resulting in eight versus twelve drillings for the navigated versus conventional group, respectively (p = 0.021). K-wire trajectory showed an MC orientation in most of the specimen (n = 9, group NP 4, group CP 5). CONCLUSIONS: Image-free navigated coracoclavicular drilling for the repair of acromioclavicular joint dislocation has higher first-pass accuracy in comparison to conventional drill guide-based placement and, therefore, may enable a precise anatomic position of the drill holes and reduce the risk of an iatrogenic coracoid fracture.