A novel osteotomy in shoulder joint replacement based on analysis of the cartilage/metaphyseal interface

A comparison of patient-specific instrumentation to navigation for conducting humeral head osteotomies during shoulder arthroplasty

Background

The humeral head osteotomy during shoulder arthroplasty influences humeral component height, version and possibly neck-shaft angle. These parameters all potentially influence outcomes of anatomic and reverse shoulder replacement to a variable degree. Patient-specific guides and navigation have been studied and utilized clinically for glenoid component placement. Little, however, has been done to evaluate these techniques for humeral head osteotomies. The purpose of this study, therefore, was to evaluate the use of patient-specific guides and surgical navigation for executing a planned humeral head osteotomy.

Methods

The DICOM images of 10 shoulder computed tomography scans (5 normal and 5 osteoarthritic) were used to print 3D polylactic models of the humerus. Each model was duplicated, such that there were 2 identical groups of 10 models. After preoperative planning of a humeral head osteotomy, Group 1 underwent osteotomy via a patient-specific guide, while group 2 underwent a real time navigated osteotomy with an optically tracked sagittal saw. The cut height (millimeters), version (degrees) and neck-shaft angle (degrees) were recorded and statistically compared between groups.

Results

There were no statistically significant differences between patient-specific guides and navigation for osteotomy cut height (P = .45) and humeral version (P = .059). Navigation, however, resulted in significantly less neck-shaft angle error than the patient specific guides (P = .023). Subgroup analysis of the osteoarthritic cases showed statistical significance for navigation resulting in less version error than the patient specific guides (P = .048).

Conclusion

No significant differences were found between patient specific guides and navigation for recreation of the preoperatively planned humeral head cut height and version. Neck-shaft angle, however, had significantly less deviation from the preoperative plan when conducted with navigation.

Immediate Fixation Versus Late Osteotomy for an Unusual Scapula Body Fracture: A Report of 2 Cases

CASE

We present 2 unusual scapula fractures that do not meet published thresholds for surgical intervention; 1 initially managed surgically with a good functional result and 1 conservatively with a poor outcome. The second patient subsequently underwent osteotomy and fixation with good effect.

CONCLUSION

Despite not reaching published levels of displacement or angulation usually considered for surgical intervention, these cases demonstrate that combined patterns of scapula injury can cause functional disability if managed conservatively. The authors believe that combination patterns of injury should be considered for early surgery to avoid loss of function caused by healing of the fracture(s) in malposition.

Computational optimization of graft tension in simulated superior capsule reconstructions

Superior capsular reconstruction has received increased attention as a surgical technique to address massive "irreparable" rotator cuff tears; however, the functional limitations and surgical techniques associated with this repair have yet to be sufficiently explored. The goal of this study was to utilize a multidisciplinary approach to characterize the biomechanics of this repair by: (i) identifying activities of daily living that may overburden the graft; and (ii) optimizing surgical techniques used during implantation. This experiment was completed in three phases. First, graft failure mechanics were characterized by performing an in vitro experiment. Second, in vivo shoulder kinematics associated with various activities were recorded with 3-D motion capture techniques. Finally, an in silico model was used to assess graft strains. Results show that motions involving posterior shoulder rotation, such as back washing, lead to graft strains that may cause failure. Output from the optimization suggests that orienting the humerus in approximately 25° abduction, and 20° internal rotation during implantation will result in optimal graft performance. Clinical Significance: The novel paradigm used in this study demonstrates the utility of coupling in vitro, in vivo, and in silico modeling techniques in one cohesive experiment. This paradigm presents an additional tool, aside from clinical studies and cadaveric experimentation, to better predict and understand the strengths and limitations of superior capsular reconstruction. This approach has potential to be translated to other soft tissue repairs and may provide valuable information to clinicians and rehabilitative specialists to manage patient expectations and guide rehabilitation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2789-2796, 2018.

Understanding the Basics of Computational Models in Orthopaedics: A Nonnumeric Review for Surgeons

Computational models represent more than just finite element analysis, a term that many clinicians may know and globally apply. Over the past 30 years, many published studies have addressed clinically relevant orthopaedic questions with speed and precision by using a wide variety of computational approaches. Given such a wide spectrum of techniques, clinicians often do not have a full understanding of the methods used to create models and therefore do not appreciate the strengths, weaknesses, and potential pitfalls of published results. The short, nonnumeric summaries of the methodologies employed for various computational approaches presented here can help address this issue.

Humeral head osteotomy in shoulder arthroplasty: a comparison between anterosuperior and inferoanterior resection techniques

BACKGROUND

The best chance that a shoulder arthroplasty will restore motion and muscle balance across the glenohumeral joint is by closely replicating natural articular morphology. Defining the humeral osteotomy plane along clear landmarks at the anatomic neck is critical. We hypothesized that a new osteotomy, based on alternative landmarks on the anatomic neck, would restore 3-dimensional humeral head morphology more reliably than the traditional osteotomy.

METHODS

The anatomic neck was digitized in 30 human cadaver shoulders and compared with its 3-dimensional computed tomography reconstruction. Two different osteotomy techniques were virtually performed: the traditional, following the anterosuperior anatomic neck; and a new technique, defined by the inferoanterior anatomic neck. The length-width difference and orientation (retroversion, inclination) of the resection area were compared between the techniques and with native anatomy.

RESULTS

Length-width difference of the anterosuperior resection area was higher than in the inferoanterior osteotomy (6 ± 2 mm vs. 3 ± 1 mm; P < .001). Retroversion of the anterosuperior resection plane was higher than the native head (50° ± 12° vs. 37° ± 11°; P < .001), whereas retroversion after the inferoanterior osteotomy (32° ± 12°) did not differ from native (P = .057). Inclination differed after the anterosuperior osteotomy (129° ± 5°) and the inferoanterior osteotomy (127° ± 4°) compared with the native head (134° ± 4°; P ≤ .001).

CONCLUSION

The inferoanterior referenced osteotomy generated a more circular resection area, matching the native humeral head retroversion more closely than in the anterosuperior technique. This study suggests that in shoulder arthroplasty, the humeral resection level should be referenced at the inferoanterior rather than the anterosuperior anatomic neck. Further studies should investigate the biomechanical effects of this alternative resection plane.

Comparison of measurements of the glenopolar angle in 3D CT reconstructions of the scapula and 2D plain radiographic views

AIMS

The aim of this study was to analyse the effect of altered viewing perspectives on the measurement of the glenopolar angle (GPA) and the differences between these measurements made on 3D CT reconstructions and anteroposterior (AP) scapular view radiographs.

MATERIALS AND METHODS

The influence of the viewing perspective on the GPA was assessed, as were the differences in the measurements of the GPA between 3D CT reconstructions and AP scapular view radiographs in 68 cadaveric scapulae.

RESULTS

The median GPA in 3D reconstructions and AP scapular views were 42.7° (95% confidence intervals (CI), 42.0° to 43.5°) and 41.3° (95% CI 40.4° to 42.0°) respectively (p < 0.001). All but five of 20 malpositions demonstrated a significant difference in GPA compared with the respective AP scapular view (p ≤ 0.005). The GPA was most susceptible to malposition in retroversion/anteversion. Inter- and intra-observer reliability for all measurements of the GPA was excellent for 3D CT reconstructions (intraclass correlation (ICC) 0.93 (95% CI 0.87 to 0.96) and 0.94 (95% CI 0.89 to 0.97), respectively) and higher than on AP scapular radiographs (p < 0.001). The intra- and inter-observer reliability was excellent in AP scapular views and malpositions in extension/flexion (ICC ≥ 0.84) but tended to decrease with increasing viewing angle in retroversion/anteversion.

CONCLUSION

These data suggest that 3D reconstructions are more reproducible than AP scapular radiographs in the assessment of the GPA and should be used to compare data in different studies, to predict outcome, define malunion, and act as an indication for surgery in patients with a scapular fracture. Cite this article: Bone Joint J 2016;98-B:1510-16.

Three-dimensional anthropometric analysis of the glenohumeral joint in a normal Japanese population

BACKGROUND

An understanding of normal glenohumeral geometry is important for anatomical reconstruction in shoulder arthroplasty. Unfortunately, the details of the glenohumeral joint in Asian populations have not been sufficiently evaluated. The purpose of this study was to evaluate the 3-dimensional geometry of the glenohumeral joint in the normal Japanese population and to clarify its morphologic features.

METHODS

Anthropometric analysis of the glenohumeral joint was performed using computed tomography scans of 160 normal shoulders from healthy Japanese volunteers. The glenohumeral dimensions and orientation were analyzed 3-dimensionally. Sex differences and correlations between sides and among the respective parameters in the glenohumeral dimensions were evaluated.

RESULTS

The normal Japanese humeral head has an average width of 41.4 mm, thickness of 13.2 mm, diameter of 42.9 mm, retroversion of 32°, and inclination of 135°. The glenoid has an average height of 31.5 mm, width of 23.1 mm, diameter of 62.0 mm, retroversion of 0°, and inferior inclination of 2°. The values of the glenohumeral dimensions were uniform in men and women, and the humeral head and glenoid were larger in men than in women. The glenohumeral size was well correlated between the 2 sides, and there were direct correlations among the heights, humeral length, humeral head size, and glenoid size.

CONCLUSIONS

The present study revealed the glenohumeral geometry in the normal Japanese population. The present results would be useful to determine the size of implants and to improve the design of shoulder prostheses that reflect the normal anatomy of the Asian glenohumeral joint.