Use of three-dimensional fluoroscopy to determine intra-articular screw penetration in proximal humeral fracture model

Periarticular screws: what's in and what's out of the joint?

Periarticular hardware placement can be challenging and a source of angst for orthopaedic surgeons due to fear of penetrating the articular surface and causing undue harm to the joint. In recent years, many surgeons have turned to computed tomography (CT) and other intraoperative or postoperative modalities to determine whether hardware is truly extraarticular in areas of complex anatomy. Yet, these adjuncts are expensive, time consuming, and often unnecessary given the advancement in understanding of intraoperative fluoroscopy. We present a review article with the goal of empowering surgeons to leave the operating room, with fluoroscopy alone, assured that all hardware is beneath the articular surface that is being worked on. By understanding a simple concept, surgeons can extrapolate the information in this article to any joint and bony surface in the body. While targeted at both residents and surgeons who may not have completed a trauma fellowship, this review can benefit all orthopaedic surgeons alike.

A novel method to assess intraarticular screw penetration into the joint space

Objectives

This study aims to propose a novel method to detect articular penetration of screws by relying on their electrical conductivity properties and control the validity of this method.

Materials and methods

In this ex vivo study, conducted between June 2017 and August 2017, we used five fresh sheep shoulder joints. First, the shoulder joint space was filled with saline solution. An insulated cannula was placed in the joint capsule, and a conductive wire was introduced into the joint via this cannula. A single titanium screw was inserted from the tuberculum majus into the posteroinferior quadrant of the humeral head under fluoroscopic observation. Conductivity was continuously measured using a digital multimeter. When a sudden decrease in conduction resistance was detected, fluoroscopic images were obtained in the anteroposterior (AP) and lateral directions. These images were assessed for penetration by a blinded surgeon. Penetration was confirmed by dissection of the joint.

Results

There was a significant decrease in electrical resistance when screw penetration occurred (p<0.001). All penetration events were confirmed using our novel method. For all five of the specimens, either AP or lateral images could not be used to confirm penetration. For two of these specimens, penetration was undetectable in both AP and lateral fluoroscopic images, but a decrease in resistance was recorded.

Conclusion

The described method exhibits greater sensitivity and accuracy for metal penetration to joint, and it is effective in detecting screws in the joints. The novel method described in this paper was applied in a prototype setting, and we believe that this concept can continue to be developed.

Detection of Intra-Articular Screw Penetration of Proximal Humerus Fractures: Is Postoperative Computed Tomography the Necessary Imaging Modality?

RATIONALE AND OBJECTIVE

Screw penetration is the common complication of proximal humerus fractures treated with locking plates. This study compared postoperative plain radiography to computed tomography (CT) for their abilities in determining screw penetration, and was to evaluate whether advanced imaging modalities (two-dimensional [2D] CT; three-dimensional [3D] CT) could increase surgeons' level of confidence regarding their diagnoses.

MATERIALS AND METHODS

Two observers reviewed radiological images of 134 patients who sustained proximal humerus fractures treated with locking plates. The observers were asked to answer two questions: (1) Is there screw penetrating into glenohumeral joint for this patient (Yes/No)? and (2) On a scale from 0 to 10, how confident are you about this diagnosis: (0-10) (0 = not at all confident; 10 = very confident)? Three evaluations were performed: (1) plain radiography alone, (2) radiography and 2D CT 4 weeks later, and (3) radiography in combination with 2D and 3D CT after that. This process was then repeated for intraobserver analysis.

RESULTS

CT obtained almost perfect interobserver and intraobserver agreement (0.818-0.961), which was higher than radiography (0.377-0.655). For incidence of screw penetration, the significant difference was found between radiographs and CT images (P< .0125), but not between 2D and 3D CT images (P > .05). For confidence of diagnosis, the differences between imaging modalities were significant (all P< .001).

CONCLUSIONS

We suggest that postoperative CT scans (especially 3D CT images) should be used to evaluate the intra-articular screw penetration of proximal humerus fractures, especially when surgeons have not enough confidence in determining screw penetration using radiography alone.

Clinical Effects of the Probing Method with Depth Gauge for Determining the Screw Depth of Locking Proximal Humeral Plate

Background. The use of locking plates has gained popularity to treat proximal humeral fractures. However, the complication rates remain high. Biomechanical study suggested that subchondral screw-tip abutment significantly increased the stability of plant. We present a simple method to obtain the proper screw length through the depth gauge in elderly patients and compared the clinical effects with traditional measuring method. Methods. 40 patients were separated into two groups according to the two surgical methods: the probing method with depth gauge and the traditional measuring method. The intraoperative indexes and postoperative complications were recorded. The Constant and Murley score was used for the functional assessment in the 12th month. Results. Operative time and intraoperative blood loss indicated no statistical differences. X-ray exposure time and the patients with screw path penetrating the articular cartilage significantly differed. Postoperative complications and Constant and Murley score showed no statistical differences. Conclusions. Probing method with depth gauge is an appropriate alternative to determine the screw length, which can make the screw-tip adjoin the subchondral bone and keep the articular surface of humeral head intact and at the same time effectively avoid frequent X-ray fluoroscopy and adjusting the screws.