Three-dimensional measurement of the course of the radial nerve at the posterior humeral shaft: An in vivo anatomical study

Accuracy of pelvic bone segmentation for 3d printing: a study of segmentation accuracy based on anatomic landmarks to evaluate the influence of the observer

BACKGROUND

3D printing has a wide range of applications and has brought significant change to many medical fields. However, ensuring quality assurance (QA) is essential for patient safety and requires a QA program that encompasses the entire production process. This process begins with imaging and continues on with segmentation, which is the conversion of Digital Imaging and Communications in Medicine (DICOM) data into virtual 3D-models. Since segmentation is highly influenced by manual intervention the influence of the users background on segmentation accuracy should be thoroughly investigated.

METHODS

Seventeen computed tomography (CT) scans of the pelvis with physiological bony structures were identified, anonymized, exported as DICOM data sets, and pelvic bones were segmented by four observers with different backgrounds. Landmarks were measured on DICOM images and in the segmentations. Intraclass correlation coefficients (ICCs) were calculated to assess inter-observer agreement, and the trueness of the segmentation results was analyzed by comparing the DICOM landmark measurements with the measurements of the segmentation results. The correlation between segmentation trueness and segmentation time was analyzed.

RESULTS

The lower limits of the 95% confidence intervals of the ICCs for the seven landmarks analyzed ranged from 0.511 to 0.986. The distance between the iliac crests showed the highest agreement between observers, while the distance between the ischial tuberosities showed the lowest. The distance between the upper edge of the symphysis and the promontory showed the lowest deviation between DICOM measurements and segmentation measurements (mean deviations < 1 mm), while the intertuberous distance showed the highest deviation (mean deviations 14.5-18.2 mm).

CONCLUSIONS

Investigators with diverse backgrounds in segmentation and varying experience with slice images achieved pelvic bone segmentations with landmark measurements of mostly high agreement in a setup with high realism. In contrast, high variability was observed in the segmentation of the coccyx. In general, interobserver agreement was high, but due to measurement inaccuracies, landmark-based approaches cannot conclusively show that segmentation accuracy is within a clinically tolerable range of 2 mm for the pelvis. If the segmentation is performed by a very inexperienced user, the result should be reviewed critically by the clinician in charge.

Anterior medial minimally invasive plate osteosynthesis for humeral shaft fractures shows superior early shoulder and elbow function compared to locking compression plate: A retrospective study

INTRODUCTION

Humeral shaft fractures are a common injury of the upper limb, with the primary surgical treatment modality being the locking compression plate (LCP) technique. The advent of Anterior medial minimally invasive plate osteosynthesis (MIPO) technology has led to its gradual implementation in clinical practice. However, the efficacy and long-term outcomes of MIPO require further investigation. The objective of this study is to compare the therapeutic effects of LCP and MIPO in the management of humeral shaft fractures.

METHODS

The present study conducted a retrospective review of patients diagnosed with humeral shaft fractures between June 2016 and December 2019. The patients were divided into MIPO and LCP groups based on the different surgical methods. The study analyzed the length of hospital stay, radiation exposure, operative time, and postoperative Disabilities of the Arm, Shoulder and Hand (DASH) scores using statistical methods.

RESULTS

A total of 53 patients who met the inclusion criteria were included in the study. The MIPO group demonstrated a statistically significant reduction in length of hospital stay compared to the LCP group (length of hospital stay: 5.39 ± 2.23 days vs 12.00 ± 7.19 days, P < 0.001). All patients achieved callus formation after surgery. However, the MIPO group had significantly more radiation exposures than the LCP group (45.96 ± 19.49 vs 5.33 ± 2.20, P < 0.001). Additionally, there was no statistically significant difference observed in the time from admission to surgery, operative time,and healing time between the two groups (the time from admission to surgery: P = 0.593; operative time: P = 0.407; Healing time: P = 0.664). During the postoperative follow-up, the MIPO group exhibited significantly lower 6-week and 3-month DASH scores compared to the LCP group (6-week: 34.17 ± 12.16 vs 45.65 ± 22.94, P = 0.028; 3-month: 17.43 ± 11.70 vs 30.12 ± 9.80, P < 0.001). However, there was no statistically significant difference in the 6-month and 12-month DASH scores between the two groups (6-month: P = 0.787; 12-month: P = 0.058).

CONCLUSION

The MIPO technique provides better short-term functional recovery of the shoulder and elbow compared to the LCP technique in the treatment of humeral shaft fractures, while ensuring equivalent surgical healing.

Improving Left Atrial Appendage Occlusion Device Size Determination by Three-Dimensional Printing-Based Preprocedural Simulation

Background

The two-dimensional (2D)-based left atrial appendage (LAA) occluder (LAAO) size determination by using transesophageal echocardiography (TEE) is limited by the structural complexity and wide anatomical variation of the LAA.

Objective

This study aimed to assess the accuracy of the LAAO size determination by implantation simulation by using a three-dimensional (3D)-printed model compared with the conventional method based on TEE.

Methods

We retrospectively reviewed patients with anatomically and physiologically properly implanted the Amplatzer Cardiac Plug and Amulet LAAO devices between January 2014 and December 2018 by using the final size of the implanted devices as a standard for size prediction accuracy. The use of 3D-printed model simulations in device sizing was compared with the conventional TEE-based method.

Results

A total of 28 cases with the percutaneous LAA occlusion were reviewed. There was a minimal difference [−0.11 mm; 95% CI (−0.93, 0.72 mm); P = 0.359] between CT-based reconstructed 3D images and 3D-printed left atrium (LA) models. Device size prediction based on TEE measurements showed poor agreement (32.1%), with a mean difference of 2.3 ± 3.2 mm [95% CI (−4.4, 9.0)]. The LAAO sizing by implantation simulation with 3D-printed models showed excellent correlation with the actually implanted LAAO size (r = 0.927; bias = 0.7 ± 2.5). The agreement between the 3D-printed and the implanted size was 67.9%, with a mean difference of 0.6 mm [95% CI (−1.9, 3.2)].

Conclusion

The use of 3D-printed LA models in the LAAO size determination showed improvement in comparison with conventional 2D TEE method.

The radial nerve at revision/redo surgery - using the lower lateral cutaneous nerve to prevent a postoperative radial nerve deficit

Background

The posterior approach to the humeral shaft is commonly used for surgical procedures on the humeral shaft. We present our experiences using the modification of the surgical exposure described by Gerwin M. which we have found useful at the time of revision surgery.

Methods

Between 2014 and 2019, six patients who underwent a revision surgical procedure for a nonunion of the humeral shaft where a prior surgical procedure was performed through a posterior incision were included. The approach used a modification of the posterior approach described by Gerwin M. where the lower lateral cutaneous nerve branch of the radial nerve is used to identify trace, mobilize, retract, and protect the radial nerve to achieve adequate exposure of the humeral shaft.

Results and Discussion

None of the patients had a postoperative nerve deficit.Adequate exposure to aid hardware removal, osteosynthesis, and bone grafting was achieved in all patients.

Conclusion

The modification of the posterior approach described by Gerwin M. is useful at the time of revision or redo surgery on the humeral shaft where other bony and soft tissue landmarks are altered to prevent an iatrogenic injury to the radial nerve while providing adequate exposure to treat a nonunion.