A Convergent Tibial Tunnel Technique for Concomitant Anterior Cruciate Ligament Reconstruction and Meniscal Root Repair.

Modern arthroscopic knee-reconstruction techniques involve the use of multiple bone tunnels and fixation devices to restore the anatomy and stability of the knee after traumatic injury. In these injuries, however, tunnel collision can be problematic, especially when combining anterior cruciate ligament reconstruction with meniscal root repairs or multiligament reconstructions. We describe a multiple tibial tunnel technique to allow fixation of both anterior cruciate ligament graft and meniscal roots through convergence to a single tibial cortical aperture.

Electronic Control of the Position of the Pb Atom on the Surface of B8 Borozene in the PbB8 Cluster.

Spontaneous symmetry-breaking is common in chemical and physical systems. Here, we show that by adding an electron to the C7v PbB8 cluster, which consists of a planar B8 disk with the Pb atom situated along the C7 axis, the Pb atom spontaneously moves to the off-axis position in the PbB8- anion. Photoelectron spectroscopy of PbB8- reveals a broad ground-state transition and a large energy gap, suggesting a highly stable closed-shell PbB8 borozene complex and a significant geometry change upon electron detachment. Quantum chemistry calculations indicate that the lowest unoccupied molecular orbital of the C7v PbB8 cluster is a degenerate π orbital mainly consisting of the Pb 6px and 6py atomic orbitals. Occupation of one of the 6p orbitals spontaneously break the C7v symmetry in the anion due to the Jahn-Teller effect. The large amplitude of the position change of Pb in PbB8- relative to PbB8 is surprising owing to bonding interactions between the Pb 6p orbital with the π orbital of the B8 borozene.

The Use of an External Cutting Guide for Patient-Specific Bone Grafting in Reverse Total Shoulder Arthroplasty: A Novel Technique.

Glenoid bone loss remains a substantial challenge in reverse shoulder arthroplasty and failure to address such bone loss may lead to implant malpositioning, instability and/or premature baseplate loosening. Currently, management of glenoid bone loss can be achieved by metal augmentation or bone grafting (ie, autograft or allograft). At the present time, options for creating and shaping glenoid bone grafts include free-hand techniques and simple reusable cutting guides that create the graft at a standard shape/angle. To our knowledge, there is no external guide available that enables surgeons to accurately prepare the bone graft to the desired dimensions/shape (ie, trapezoid or biplanar) to correct the glenoid deformity. In this article, we present a novel surgical technique that utilizes an external guide for creating a patient-specific bone graft to address glenoid deformity in the setting of reverse total shoulder arthroplasty.

High-Energy Transsyndesmotic Ankle Fracture Dislocation-Injury Characteristics, Radiographic Outcomes, and Factors Affecting the Rate of Posttraumatic Arthritis in Logsplitter Injuries.

OBJECTIVES: To investigate patient demographics, injury characteristics, radiographic outcomes, and identify risk factors for developing posttraumatic arthritis in high-energy transsyndesmotic ankle fracture dislocations or "logsplitter" injuries. DESIGN: Retrospective cohort study. SETTING: Academic level one trauma center. PATIENTS/PARTICIPANTS: Twenty-seven adult patients with logsplitter injuries. INTERVENTION: All patients were treated with open reduction internal fixation, with possible addition of syndesmosis screw(s) and deltoid repair. MAIN OUTCOME MEASUREMENTS: The rate of posttraumatic arthritis at one year along with rate and reasons for reoperation. RESULTS: Twenty-seven patients were included with a mean follow-up of 14.5 ± 12.5 months. At one-year postoperative, 14 of the 20 patients (70%) demonstrated posttraumatic arthritis. Two patients (7.4%) went onto fusion. The reoperation rate was 51.9%. There was no significant difference in the arthritis rate with the number of syndesmosis screws used, quality of reduction, or addition of deltoid repair. CONCLUSIONS: The logsplitter injury is one with devastating outcomes and high rates of arthritis; it should be considered separately from conventional ankle fractures. The role of deltoid repair remains unclear. Further study of this injury pattern is required. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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.

Photoelectron Spectroscopy of Size-Selected Bismuth-Boron Clusters: BiBn- (n = 6-8).

Because of its low toxicity, bismuth is considered to be a "green metal" and has received increasing attention in chemistry and materials science. To understand the chemical bonding of bismuth, here we report a joint experimental and theoretical study on a series of bismuth-doped boron clusters, BiBn- (n = 6-8). Well-resolved photoelectron spectra are obtained and are used to understand the structures and bonding of BiBn- in conjunction with theoretical calculations. Global minimum searches find that all three BiBn- clusters have planar structures with the Bi atom bonded to the edge of the planar Bn moiety via two Bi-B σ bonds as well as π bonding by the 6pz orbital. BiB6- is found to consist of a double-chain B6 with a terminal Bi atom. Both BiB7- and BiB8- are composed of a Bi atom bonded to the planar global minima of the B7- and B8- clusters. Chemical bonding analyses reveal that BiB6- is doubly antiaromatic, whereas BiB7- and BiB8- are doubly aromatic. In the neutral BiBn (n = 6-8) clusters, except BiB6 which has a planar structure similar to the anion, the global minima of both BiB7 and BiB8 are found to be half-sandwich-type structures due to the high stability of the doubly aromatic B73- and B82- molecular wheel ligands.

Does the Walch type B shoulder have a transverse force couple imbalance? A volumetric analysis of segmented rotator cuff muscles in osteoarthritic shoulders.

BACKGROUND: The etiology of the Walch type B shoulder remains unclear. We hypothesized that a scapulohumeral muscle imbalance, due to a disturbed transverse force couple (TFC) between the anterior and posterior rotator cuff muscles, may have a role in the pathogenesis of the type B morphology. The purpose of this study was to determine whether there is a TFC imbalance in the Walch type B shoulder using an imaging-based 3-dimensional (3D) volumetric and fatty infiltration assessment of segmented rotator cuff muscles. METHODS: Computed tomography images of 33 Walch type A and 60 Walch type B shoulders with the complete scapula and humerus including the distal humeral epicondyles were evaluated. The 3D volumes of the entire subscapularis, supraspinatus, and infraspinatus-teres minor (Infra-Tm) were manually segmented and analyzed. Additionally, anthropometric parameters including glenoid version, glenoid inclination, posterior humeral head subluxation, and humeral torsion were measured. The 3D muscle analysis was then compared with the anthropometric parameters using the Wilcoxon rank sum and Kruskal-Wallis tests. RESULTS: There were no significant differences (P > .200) in muscle volume ratios between the Infra-Tm and the subscapularis in Walch type A (0.93) and type B (0.96) shoulders. The fatty infiltration percentage ratio, however, was significantly greater in type B shoulders (0.94 vs. 0.75, P < .001). The Infra-Tm to subscapularis fatty infiltration percentage ratio was significantly larger in patients with >75% humeral head subluxation than in those with 60%-75% head subluxation (0.97 vs. 0.74, P < .001) and significantly larger in patients with >25° of retroversion than in those with <15° of retroversion (1.10 vs. 0.75, P = .004). The supraspinatus fatty infiltration percentage was significantly lower in Walch type B shoulders than type A shoulders (P = .004). Walch type A shoulders had mean humeral retrotorsion of 22° ± 10° whereas Walch type B shoulders had humeral retrotorsion of only 14° ± 9° relative to the epicondylar axis (P < .001). CONCLUSION: The TFC is in balance in the Walch type B shoulder in terms of 3D volumetric rotator cuff muscle analysis; however, the posterior rotator cuff does demonstrate increased fatty infiltration. Posterior humeral head subluxation and glenoid retroversion, which are pathognomonic of the Walch type B shoulder, may lead to a disturbance in the length-tension relationship of the posterior rotator cuff, causing fatty infiltration.

Publication Productivity Among Academic Orthopaedic Surgeons in Canada.

Objective The Hirsch Index (h-index) and m-index are often utilized to assess academic productivity and have been widely found to have a positive association with academic promotion and grant selection. The aim of this study was to assess the relationship between these indices and academic ranks among Canadian orthopaedic surgery faculty members. Methods Five hundred and sixty-seven Canadian orthopaedic surgery faculty members associated with residency training programs were included in the study. H-indices of individual faculty members were obtained through Elsevier's Scopus database. Faculty members' year of residency graduation was recorded from their respective licensing body database and was utilized as a surrogate for the start of their academic career to determine career duration and calculate the m-index. Faculty members were divided based on their academic rank (assistant, associate and full professors) and subspecialty. Results Increased h-index, m-index and long career duration were associated with increased academic rank, while gender did not demonstrate an association. Overall, males had a significantly higher h-index compared to females, but no significant difference was observed when comparing the m-index between genders. The m-index varied between subspecialties among senior faculty, but not among junior-ranked faculty. Conclusion Bibliometric academic productivity using h-index and m-index is associated with academic ranking among Canadian orthopaedic surgeons at training institutions. Although these indices may provide insight into the academic merits of faculty members, caution must be taken about utilizing it indiscriminately and their limitations must be strongly considered.

Observation of Transition-Metal-Boron Triple Bonds in IrB2 O- and ReB2 O.

Multiple bonds between boron and transition metals are known in many borylene (:BR) complexes via metal dπ →BR back-donation, despite the electron deficiency of boron. An electron-precise metal-boron triple bond was first observed in BiB2 O- [Bi≡B-B≡O]- in which both boron atoms can be viewed as sp-hybridized and the [B-BO]- fragment is isoelectronic to a carbyne (CR). To search for the first electron-precise transition-metal-boron triple-bond species, we have produced IrB2 O- and ReB2 O- and investigated them by photoelectron spectroscopy and quantum-chemical calculations. The results allow to elucidate the structures and bonding in the two clusters. We find IrB2 O- has a closed-shell bent structure (Cs , 1 A') with BO- coordinated to an Ir≡B unit, (- OB)Ir≡B, whereas ReB2 O- is linear (C∞v , 3 Σ- ) with an electron-precise Re≡B triple bond, [Re≡B-B≡O]- . The results suggest the intriguing possibility of synthesizing compounds with electron-precise M≡B triple bonds analogous to classical carbyne systems.

Planar B41- and B42- clusters with double-hexagonal vacancies.

Since the discovery of the B40 borospherene, research interests have been directed to the structural evolution of even larger boron clusters. An interesting question concerns if the borospherene cages persist in larger boron clusters like the fullerenes. Here we report a photoelectron spectroscopy (PES) and computational study on the structures and bonding of B41- and B42-, the largest boron clusters characterized experimentally thus far. The PE spectra of both clusters display broad and complicated features, suggesting the existence of multiple low-lying isomers. Global minimum searches for B41- reveal three low-lying isomers (I-III), which are all related to the planar B40- structure. Isomer II (Cs, 1A') possessing a double hexagonal vacancy is found to agree well with the experiment, while isomers I (Cs, 3A'') and III (Cs, 1A') both with a single hexagonal vacancy are also present as minor isomers in the experiment. The potential landscape of B42- is found to be much more complicated with numerous low-lying isomers (VII-XII). The quasi-planar structure VIII (C1, 2A) containing a double hexagonal vacancy is found to make major contributions to the observed PE spectrum of B42-, while the other low-lying isomers may also be present to give rise to a complicated spectral pattern. Chemical bonding analyses show isomer II of B41- (Cs, 1A') and isomer VIII of B42- (C1, 2A) are π aromatic, analogous to that in the polycyclic aromatic hydrocarbon C27H13+ (C2v, 1A1). Borospherene cage isomers are also found for both B41- and B42- in the global minimum searches, but they are much higher energy isomers.