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

3D C-arm navigated suture button implantation for AC joint dislocations - the pilot study

PURPOSE

The surgical treatment of acute traumatic AC joint dislocations is still a subject of scientific debate in the literature. The arthroscopically assisted stabilization procedure with a suture button system has been successfully established and is widely used in daily practice. It is minimally invasive and allows the anatomical reconstruction of the torn coracoclavicular ligaments in one step with a permanent implant that does not have to be removed in a second operation. This clinical pilot study is the first to describe the new method of navigated suture button implantation with the future aim of further reducing surgical invasiveness and further increasing surgical precision.

MATERIALS AND METHODS

10 patients with a Rockwood 3b/5 injury could be included in the prospective study (DRKS00031855) within 5 months according to inclusion and exclusion criteria. Surgical stabilization was performed with a suture button system via a navigated coracoclavicular drill tunnel. Demographic and radiological data as well as information on health and shoulder function were collected from patient records, X-rays, DVT scan and 3 questionnaires (DASH, NHS and Eq. 5D) at the preoperative, intraoperative and postoperative (discharge, 6 weeks and 3 months) time points.

RESULTS

All operations could be performed within 8.8 days (± 6.81) after trauma. The average operation time was 50.3 min (± 8.81). The mean distance of the drill hole in the clavicle to the AC joint was 26.6 mm (± 2.63). The radiologically measured vertical coracoclavicular distance was 38.8 mm (± 6.16) at discharge and 41.11 mm (± 7.51) at 3 months. This loss of reduction was not statistically significant. In contrast, the DASH, NHS and Eq. 5D results showed significant improvement from discharge to 3 months postoperatively.

CONCLUSION

Image-guided 3D C-arm navigated AC joint suture button stabilization is feasible in everyday surgical practice. It may be possible to achieve a further reduction in invasiveness while at the same time increasing the accuracy of implant positioning. Further clinical studies with a larger number of patients and a longer follow-up period are necessary to enable a comparison with conventional methods.

3D C-arm navigated acromioclavicular joint stabilization

INTRODUCTION

Surgical treatment options for acromioclavicular joint separations are varied. Frequently, suspension devices (SD) are inserted for stabilization under arthroscopic view. This study investigates the feasibility and accuracy of three-dimensional (3D) digital-volume-tomography (DVT) C-arm navigated implantation with regard to the general trend toward increasingly minimally invasive procedures.

MATERIALS AND METHODS

The implantation of a TightRope® suture button system (SD) via a navigated vertical drill channel through the clavicle and coracoid was investigated in 10 synthetic shoulder models with a mobile isocentric C-arm image intensifier setup in the usual parasagittal position. Thereby, in addition the placement of an additive horizontal suture cerclage via a navigated drill channel through the acromion was assessed.

RESULTS

All vertical drill channels in the Coracoclavicular (CC) direction could be placed in a line centrally through the clavicle and the coracoid base. The horizontal drill channels in the Acromioclavicular (AC) direction ran strictly in the acromion, without affecting the AC joint or lateral clavicle. All SD could be well inserted and anchored. After tensioning and knotting of the system, the application of the horizontal AC cerclage was easily possible. The image quality was good and all relevant structures could be assessed well.

CONCLUSION

Intraoperative 3D DVT imaging of the shoulder joint using a mobile isocentric C-arm in the usual parasagittal position to the patient is possible. Likewise, DVT navigated SD implantation at the AC joint in CC and AC direction on a synthetic shoulder model. By combining both methods, the application in vivo could be possible. Further clinical studies on feasibility and comparison with established methods should be performed.

Intraoperative 3D imaging in plate osteosynthesis of proximal humerus fractures

INTRODUCTION

Proximal humerus fractures are common and often associated with osteoporosis in the elderly. Unfortunately, the complication and revision rate for joint-preserving surgical treatment using locking plate osteosynthesis is still high. Problems include insufficient fracture reduction and implant misplacement. Using conventional intraoperative two dimensional (2D) X-ray imaging control in only two planes, a completely error-free assessment is not possible.

MATERIALS AND METHODS

The feasibility of intraoperative three-dimensional (3D) imaging control for locking plate osteosynthesis with screw tip cement augmentation of proximal humerus fractures was retrospectively studied in 14 cases with an isocentric mobile C-arm image intensifier set up parasagittal to the patients.

RESULTS

The intraoperative digital volume tomography (DVT) scans were feasible in all cases and showed excellent image quality. One patient showed inadequate fracture reduction in the imaging control, which then could be corrected. In another patient, a protruding head screw was detected, which could be replaced before augmentation. Cement distribution in the humeral head was consistent around the screw tips with no leakage into the joint.

CONCLUSION

This study shows that insufficient fracture reduction and implant misplacement can be easily and reliably detected by intraoperative DVT scan with an isocentric mobile C-arm set up in the usual parasagittal position to the patient.

Analysis of the subcapital two-part humerus fracture by fluoroscopy: objective criteria for classification and decision making

BACKGROUND

Surgical decision making in the treatment of proximal humerus fractures (PHFx) is primarily based on fracture classification using standard radiographs. Due to the lack of objective criteria, this classification process is associated with high interobserver variation. In this study, we investigate the fluoroscopic analysis of humerus fractures through the surgical neck using a semi-quantitative determination of distinct angulation patterns of the proximal humerus as they appear in the image intensifier.

METHODS

Using a saw bone model, defined subcapital 2-part fracture configurations were generated and assessed radiographically. Anatomical landmarks-including the greater and lesser tuberosity as well as anatomical neck-were identified using an image converter, and the exact degree of fracture displacement with 10° up to 70° (in 10° increments) of posterior, varus or combined posterior-varus angulation was compared to nondisplaced controls. From the resultant series of radiographs, the appearance of these angulations in anteroposterior (AP) and scapular Y-views were also visualized and defined.

RESULTS

An angulation of 50° or more of any given 2-part fracture through the surgical neck is present when the greater tuberosity becomes the most proximal point in AP view (varus and combined posterior-varus angulation) or a bimodal form is found for the superior contour of the head with the lesser tuberosity being the most proximal point in the Y-view (posterior angulation).

CONCLUSION

The radiological appearance of various PHFx constellations can be well visualized using the saw bone shoulder model. The presence of angulation in accordance with the Neer classification for group III fractures can be adequately determined by analyzing the relative position of the greater or lesser tuberosity to the humeral head calotte. This can assist the surgeon's decision on whether to operate or opt for a conservative approach.

LEVEL OF EVIDENCE

Basic Science, Anatomy Study, Imaging.

Intraoperative 3D imaging in intraarticular tibial plateau fractures - Does it help to improve the patients' outcomes?

BACKGROUND

In tibial plateau fractures (TPF) the restoration of an anatomical joint surface as well as an exact subchondral screw position for postoperative stability is crucial for the outcome. The aim of this study was to determine whether the additional use of an intraoperative 3D imaging intensifier (3D) might help to improve the outcome of complex TPF.

METHODS

We performed a retrospective case-control study of a level 1 trauma center. Patients with AO/OTA 41 B3 and C-TPF operated on using a 3D imaging intensifier between November 2015 and December 2018 (3D group) were included. The outcomes of this patients were compared to patients operated without 3D imaging between January 2005 to December 2014 (2D group). The comparison of the groups was performed by matched pair analysis. The functional outcome of both groups was measured by KOOS and Lysholm Score after a follow-up period of at least 12 months. Operation time, infections and postoperative revisions were registered.

RESULTS

In total, 18 patients were included in the 3D group (mean age: 51.0± 16.4 years; 12 females) and an equal number of matching partners from the 2D group (mean age: 50.3± 15.2 years; 11 females) were found (p=0.82; p=0.79). We found 9x B3, 2x C1, 1x C2, 6x C3 fractures according to AO/OTA for each group (p=1.00) with comparable ASA score (p=0.27). The mean operation time was 127.9± 45.9 min and 116.1± 45.7 min for the 3D and 2D group (p=0.28). The mean follow-up time was 20.9± 10.7 months for the 3D and 55.5± 34.7 months for the 2D group (p< 0.001). For the 3D group a mean Lysholm overall score of 67.4± 26.8 and KOOS overall score of 72.6± 23.5 could be assessed. In contrast, a mean Lysholm overall score of 62.0± 21.4 and KOOS overall score of 65.8± 21.6 could be measured in the 2D group (p=0.39; p=0.31). Thereby, functional outcome of the 3D group showed a significant higher KOOS Sport/Rec sub score of 54.7± 35.0 in comparison to the 2D group with 26.7± 31.6 (p= 0.01). Postoperative revisions had to be performed in 27.8% of cases in both groups (p=1.00). Due to the 3D imaging an intraoperative revision was performed in 33.3% (6/18).

CONCLUSION

In our study we could show that re-reduction of the fracture or implant re-positioning were performed in relevant numbers based on the 3D imaging. This was associated with a midterm clinical benefit in regard to better KOOS Sport/Rec scores.

TRIAL REGISTRATION

AZ 488 /20-ek.

[Research progress on intra-articular screw penetration in proximal humeral fracture treated with locking plate]

Objective

To review the research progress on intra-articular screw penetration in proximal humeral fracture treated with locking plate.

Methods

The domestic and foreign literature about the proximal humeral fracture treated with locking plate was extensively reviewed. The incidence of screw penetration and risk factors were summarized from both primary and secondary screw penetrations, and the reasons of the intra-articular screw penetration and the technical solutions to avoid the penetration were analyzed.

Results

The incidence of intra-articular screw penetration is about 11%-30%, which includes primary and secondary screw penetrations. The primary screw penetration is related to improper operation, inaccurate measurement, and "Steinmetz solid" effect, which results in inadequate fluoroscopy and blind zone. The secondary screw penetration is related to the loss of reduction and varus, collapse, and necrosis of the humeral head. The risk factors for intra-articular screw penetration include the bone mass density, the fracture type, the quality of fracture reduction, the applied location, number, and length of the plate and screws, and whether medial column buttress is restored. Improved fracture reduction, understanding the geometric distribution of screws, good intraoperative fluoroscopy, and reconstruction of medial column buttress stability are the key points for success.

Conclusion

The risk of the intra-articular screw penetration in the proximal humeral fractures treated with locking plates is still high. Follow-up studies need to further clarify the cause and mechanism of screw penetration, and the risk factors that lead to screw penetration, in order to effectively prevent the occurrence of this complication.

Overdrilling increases the risk of screw perforation in locked plating of complex proximal humeral fractures - A biomechanical cadaveric study

Locked plating of proximal humerus fractures (PHF) is associated with high failure rates (15-37%). Secondary screw perforation is a prominent mode of failure for PHF and typically requires reoperation. The anatomical fracture reduction is an essential factor to prevent fixation failure. However, recent studies indicate that the risk of secondary screw perforation may increase if the articular surface is perforated during predrilling of the screw boreholes (overdrilling). This study aimed to determine whether overdrilling increases the risk of secondary screw perforation in unstable PHF. Nine pairs of human cadaveric proximal humeri were osteotomized to simulate a malreduced and highly unstable 3-part fracture (AO/OTA 11 B1.1), followed by their assignment to two study groups for overdrilling or accurate predrilling in paired design, and fixation with a locking plate. Overdrilling was defined by drilling the calcar screw's boreholes through the articular surface. All humeri were cyclically loaded to screw perforation failure. Number of cycles to initial screw loosening and final perforation failure were analysed. The accurately predrilled group revealed a significantly higher number of cycles to both initial screw loosening (p < 0.01) and final screw perforation failure (p = 0.02), compared to the overdrilled one. This is the first study reporting that drilling to the correct depth significantly increases endurance until screw perforation failure during cyclic loading after locked plating in a highly unstable PHF model. Prevention of overdrilling the boreholes could help reduce failure rates of locked plating. Future work should investigate the prevalence and consequences of overdrilling in clinics.

Secondary Perforation Risk in Plate Osteosynthesis of Unstable Proximal Humerus Fractures: A Biomechanical Investigation of the Effect of Screw Length

Secondary perforation of screws into the joint surface is a commonly reported mechanical fixation failure mode in locked plating of proximal humerus fractures (PHF). This study investigated the influence that screws tip to joint distance (TJD) has on the biomechanical risk of secondary screw perforation and the stability of PHF. Ten pairs of cadaveric proximal humeri with a wide range of bone mineral density were used. Each specimen was osteotomized and instrumented with the PHILOS plate, simulating a highly unstable 3-part fracture. Bones were randomized into a long screw group (LSG) with 4 mm TJD, or a short screw group (SSG) with 8 mm TJD. A custom biomechanical setup was used to test the samples to failure cyclically with a constant valley load and an increasing ramp. The number of cycles to the initial screw loosening event was significantly higher for the LSG (mean ± standard deviation: 17,532 ± 6,458) compared with the SSG (11,102 ± 5,440) (p < 0.01). The mode of failure during testing was lateral-inferior displacement combined with varus collapse, with calcar screws perforating first. The number of cycles to failure event for LSG (27,849 ± 5,648) was not significantly different compared with SSG (28,782 ± 7,307) (p = 0.50). Screws that purchase closer to the joint had better initial stability and resistance against loosening. Placing longer screws, within limits dictated by the surgical guide, is expected to decrease the risk of secondary perforation failures in unstable PHF. These findings require clinical corroboration. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2625-2633, 2019.

Comparison of intraoperative 2D vs. 3D imaging in open reduction and fixation of distal radius fractures

PURPOSE

In the volar plating of distal radius fractures, intraoperative three-dimensional (3D) imaging is designed to allow better judgment regarding screw and implant positioning compared with conventional intraoperative two-dimensional (2D) imaging. We evaluated the impact of these two imaging modalities on the rates of intraoperative revision and secondary surgery, as well as the need for implant removal during follow-up.

METHODS

A retrospective analysis of consecutive patients who underwent volar plate osteosynthesis for isolated distal radius fractures between January 2008 and April 2016 was performed. Patient files were evaluated for intraoperative imaging findings, intraoperative and postoperative revision rates, and implant removal during follow-up. Additional analyses of radiation exposure, operation time, and hospitalization time were performed.

RESULTS

A total of 314 patients were analyzed (mean age: 54 ± 19 years; 210 females). For 246 patients, only 2D imaging was performed, while the remaining 68 patients underwent both 2D and 3D imaging (O-Arm, Medtronic). The intraoperative revision rate was significantly (p < 0.001) higher with 3D imaging (32.4%) compared with 2D imaging (2.0%). The postoperative revision rates were similar between both the groups (2.9% vs. 2.0%; p = 0.674). Compared with 2D imaging, the use of the Medtronic O-Arm resulted in a significantly lower implant removal rate (8.8% vs. 18.7%; p = 0.036) during follow-up.

CONCLUSION

Compared with conventional 2D imaging, the use of intraoperative 3D imaging significantly increased the intraoperative revision rate and has the potential for positive long-term effects for lowering the risk of requiring an implant removal.

Optimal viewing angles of intraoperative fluoroscopy for detecting screw penetration in proximal humeral fractures: a cadaveric study

Background

To identify the optimal viewing angles for every proximal screw in PHILOS plate-fixed proximal humeral fractures.

Methods

Three fresh-frozen human cadaveric bodies with six intact shoulders were studied. All three bodies were put in the beach chair position and PHILOS plates were placed on the proximal humerus. Head screws penetrating 1 mm into the joint were fitted one by one. Fluoroscopy was conducted in the 180° horizontal plane and the 120° coronal plane to analyze each screw’s penetration in every shoulder. Images were taken every 5°, then all images were analyzed to identify the sensitive angles.

Results

The range of optimal viewing angles to visualize penetration of every head screw was identified. In the coronal plane, the angles in the range between 0° and 10° were sensitive to all screws except No. 8 and No. 9. Furthermore, penetration of screws No. 8 and 9 could not be identified on any axillary view, but could be identified in the horizontal plane from − 30° to − 10° and from 10° to 35° respectively.

Conclusions

We recommend a 0°–10° axillary view with 30° arm abduction combined with two horizontal angles in the range of − 30° to − 10° and 10° to 35° for routine fluoroscopy during surgery. Our results will be helpful in avoiding primary screw penetration.