Proximal Humerus Fracture 3-D Modeling

April 24, 2018 | Surgery

Krishn Khanna, MD ; Eugene W. Brabston, MD ; Usama Qayyum, MBBS ; Thomas R. Gardner, MCE ; William N. Levine, MD ; Charles M. Jobin, MD ; Christopher S. Ahmad, MD

Authors’ Disclosures Statement: Dr. Levine reports that he is on the board or a committee member of American Shoulder and Elbow Surgeons; is on the editorial or governing board of the Journal of the American Academy of Orthopaedic Surgeons; and is an unpaid consultant to Zimmer Biomet. Dr. Jobin reports that he is a paid consultant and a paid presenter or speaker for Acumed, LLC; is on the board or a committee member of American Shoulder and Elbow Surgeons; is a paid consultant to DePuy Synthes, a Johnson & Johnson Company; is on the editorial or governing board of the Journal of the American Academy of Orthopaedic Surgeons; is a paid presenter or speaker for Tornier; is a paid consultant for Wright Medical Technology, Inc.; and is a paid consultant and a paid presenter or speaker for Zimmer Biomet. Dr. Ahmad reports that he receives intellectual property royalties from, is a paid consultant to, and provides research support to Arthrex; receives stock or stock options from At Peak; receives publishing royalties, and financial or material support from Lead Player; receives research support from Major League Baseball; is on the editorial or governing board for Orthopedics Today; and receives research support from Stryker. The other authors report no actual or potential conflict of interest in relation to this article.

Dr. Khanna is a Postgraduate Year 4 Resident, Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, California. Dr. Brabston is an Assistant Professor, Department of Orthopaedic Surgery, University of Alabama Birmingham, Birmingham, Alabama. Mr. Qayyum is a Research Fellow in Orthopaedic Surgery, Center for Shoulder, Elbow and Sports Medicine, New York Presbyterian/Columbia University Medical Center, New York, New York. Mr. Gardner is Associate Director, Biomechanics Laboratory; Manager, Caroll Laboratories for Orthopedic Surgery; and Director of Research Support and Administration, Department of Orthopedic Surgery, Columbia University Medical Center, New York, New York. Dr. Levine is Frank E. Stinchfield Professor and Chairman, Department of Orthopedic Surgery; Chief, Shoulder Service; and Co-Director Center for Shoulder, Elbow and Sports Medicine, Columbia University Medical Center, New York, New York. Dr. Jobin is Associate Professor of Orthopedic Surgery, Residency Program Director, and Associate Shoulder Fellowship Director, Shoulder and Elbow Surgery, Columbia University Medical Center, New York, New York. Dr. Ahmad is Chief, Sports Medicine Service; Co-Director, Center for Shoulder, Elbow and Sports Medicine; Director, Pediatric and Adolescent Sports Medicine, Biomechanics Research; and Vice Chair of Clinical Research, Department of Orthopedic Surgery, Columbia University Medical Center, New York, New York.

Address correspondence to: Charles M. Jobin, MD, Shoulder & Elbow Surgery, Columbia University Medical Center, 622 West, 168th Street PH-11, New York, NY 10032 (tel, 212-308-8188; fax, 212-305-4040; email, jobin@columbia.edu).

Krishn Khanna, MD Eugene W. Brabston, MD Usama Qayyum, MBBS Thomas R. Gardner, MCE William N. Levine, MD Charles M. Jobin, MD Christopher S. Ahmad, MD . Proximal Humerus Fracture 3-D Modeling. Am J Orthop.

April 24, 2018

TAKE-HOME POINTS

Proximal humerus fractures may be better understood with 3-D CT imaging.
3-D computer modeling of complex proximal humerus fractures allows an understanding of tuebroisty reduction durring ORIF or hemiarthroplasty.
3-D modeling enhances preoperative planning for hemiarthroplasty implant size and position relative to the repaired tuberosity fragments.
3-D modeling of fracture reduction can help surgeons understand the patient’s native humeral geometry and anatomy.
Preoperative evaluation of fracture characteristics and fragment reduction help surgeons better understand surgical solutions.

Three-dimensional (3-D) modeling is increasingly being used in preoperative planning of shoulder arthroplasty and determining proper proximal humeral fracture treatment.⁵ However, no studies have examined the reconstruction of a fractured proximal humerus into native anatomy using computer simulation. The purpose of this study is to determine the accuracy and reliability of anatomically reconstructing the preinjury proximal humerus using 3-D computer models created from postinjury computed tomography (CT) scans. The results of this study could lead to useful techniques employing CT–based models for patient-specific preoperative planning of proximal humeral fracture ORIF and during tuberosity reduction and fixation during hemiarthroplasty for fracture. We hypothesize that it is feasible to reconstruct the original anatomy of the proximal humerus by using 3-D computer modeling of proximal humerus fractures with high reliability based on interobserver and intraobserver review.

METHODS

After Institutional Review Board approval was obtained, we reviewed the medical records of consecutive patients with a diagnosis of proximal humeral fracture and the treatment codes for hemiarthroplasty from 2000 to 2013. Inclusion criteria included 3- and 4-part fractures (AO classifications 11-B1, 11-B2, 11-C1, 11-C2). CT scans with insufficient quality to differentiate bone from soft tissue (inadequate signal-to-noise ratio) were excluded from the study. A total of 28 patients with adequate CT scans met the criteria for inclusion in this study.

The CT scan protocol included 0.5-mm axial cuts with inclusion of the proximal humerus in the Digital Imaging and Communications in Medicine format. These CT scans were converted into patient-specific 3-D computer models of the shoulder using Mimics software (Materialise Inc.). The use of this software to produce anatomically accurate models has previously been verified in a shoulder model.^6,7 The tuberosity fragments were then individually separated from each other using the voxel-selecting capabilities of 3-D software and manipulated with translation and rotation for anatomic reduction (Figures 1A-1D, Figure 2).

The de-identified anatomically reconstructed shoulder models were then uploaded into Materialise’s Magics rapid prototyping software, and a user-defined humeral Cartesian coordinate system was defined with anatomic landmarks as reference points to standardize the position of each model (Figure 3).^8,9

The origin was placed at the center of the best-fit sphere representing the humeral head. The y-axis was defined by the longitudinal axis of the humerus, and the x-axis was defined as the line bisecting the articular surface of the humeral head. This Cartesian coordinate system allowed us to manipulate the models in a standardized fashion, maintaining the exact positions of the humerus while making measurements.

A series of measurements were made on these models to assess the validity and reliability of the reassembly. The bicipital groove at the anatomic neck was used to measure humeral head version as described by Kummer and colleagues.¹⁰ The head-shaft angle, humeral head-greater tuberosity distance, humeral head-bicipital groove angle, and posterior and medial humeral head offset were measured directly on the reconstructed humerus.

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References