Arthroscopic Shoulder Stabilization: Is There Ever a Need to Open?

Recent studies show comparable results of arthroscopic shoulder stabilization techniques compared with the gold standard open Bankart reconstruction. Great technical advances and ever-increasing surgeon experience have rendered pathology once deemed an indication for open surgery as treatable by arthroscopic means. With this movement toward a more universal application of all-arthroscopic techniques, we might consider the following question: Is there ever a need to open? To answer this question, we must first consider normal anatomy and then appreciate the contribution of deranged pathoanatomy to recurrent instability in each individual case. The surgeon must then determine whether this is best addressed via an arthroscopic or open technique. Arthroscopy, as compared with open stabilization procedures, holds the potential benefits of decreased morbidity rates, early functional rehabilitation, and improved range of motion. Despite potential advantages, arthroscopic stabilization is clearly contraindicated when a significant pathologic lesion contributing to recurrent instability cannot be adequately addressed as a result of the limitations of current techniques or instrumentation. On the basis of this principle, we believe that sizable glenohumeral bone defects remain the only absolute contraindication to an all-arthroscopic approach. Many complicating issues, such as attenuated capsule, humeral avulsion of the glenohumeral ligament lesions, cases of revision surgery, and collision or contact athletes, exist and warrant close attention. We prefer to think of these situations as “challenges” for which both arthroscopic and open surgery should be considered, rather than as true contraindications to arthroscopic shoulder stabilization. We are, by no means, advocating arthroscopic treatment in all cases of shoulder instability, because this would represent a gross oversimplification of the issues at hand. However, we do acknowledge that the steadfast contraindications to arthroscopic shoulder stabilization are decreasing every day.     

颞下颌关节与颅面指标的计算机相关及回归分析

本文用计算机分析统计了118例(236侧)颞下颌关节的12项骨性指标及10项颅面指标的正常值及相关关系。结果表明颞下颌关节各项指标之间、颞下颌关节与颅面各主要指标之间,均存在良好的相关关系。说明颞下颌关节,特别是关节窝和髁突的形态大小具有明显的规律性。由于颅面诸指标与颞下颌关节主要指标之间高度相关,因而本文用逐步回归方法,建立了由颅面特征指标推算髁突形态的回归方程。本文的结果可为该关节的形态研究及人工关节的设计和应用提供有益的依据。     

Bullseye: preclinical evaluation of a novel structured light-based imaging workflow to inform glenoid implant positioning in total shoulder arthroplasty

BackgroundAccurate glenoid component positioning during total shoulder arthroplasty (TSA) is critical for prosthesis longevity and postoperative function. Glenoid component positioning in many TSA procedures depends on the insertion of a guide pin through the glenoid vault. However, up to 48% of TSA procedures involve guide pin malpositioning. The aim of this study was to evaluate the ability of a novel structured light imaging system to visualize glenoid guide pin position and trajectory in surgically exposed cadaveric shoulders. Computed tomography (CT)-based and magnetic resonance imaging (MRI)-based workflows and subchondral bone–based and glenoid cartilage–based workflows were compared.MethodsPreoperative cone-beam CT (CBCT) and MRI images were acquired for 5 intact cadaveric shoulders. Following deltopectoral surgical exposure, a glenoid vault guide pin was inserted through the glenoid vault of each scapula as in a clinical TSA procedure. A 3D printed optical tracker was placed over the guide pin, and a 3D optical surface image of the glenoid and tracker was acquired using a handheld structured light sensor. A postprocedural CBCT was acquired for each shoulder to verify guide pin position and trajectory. The imaging procedure was repeated after débridement of the glenoid cartilage to expose subchondral bone. The guide pin was segmented from the postprocedural CBCT image (actual guide pin). A virtual model of the tracker was aligned with a co-linear representation of the intraoperative guide pin (predicted guide pin). A series of image registrations aligned the actual and predicted guide pin positions to yield visualization accuracy, defined as the trajectory and offset errors between predicted and actual guide pins.ResultsThe mean guide pin trajectory and offset errors based on the subchondral bone were 2.22 ± 1.27° and 1.27 ± 0.46 mm for the CT-based workflow and 2.27 ± 1.72° and 1.78 ± 0.92 mm for the MRI-based workflow, respectively. Registration of the cartilage surface models visualized in the MRI images reduced accuracy to a trajectory error of 3.89 ± 1.57° (P = .147) and offset error of 2.28 ± 1.33 mm (P = .217).ConclusionThe Bullseye structured light imaging system presented an accurate approach for glenoid guide pin verification and adjustment during TSA using preoperative MRI or CT. Future development for the implementation of the Bullseye system should focus on improving surface segmentations and automation of the computer vision algorithm needed to facilitate clinical translation.     

The Glenoid Vault Outer Cortex (GVOC) radiological reference for shoulder arthroplasty evaluated in aging scapulae

BackgroundAccurate glenoid component positioning is an important determinant of outcome in a shoulder arthroplasty surgery. Optimal glenoid placement is determined using bony landmarks of the scapula. The Glenoid Vault Outer Cortex (GVOC) has been recently described as a new, more accurate radiological reference. This has, however, only been evaluated against current standard references in young patients. Further investigation of the GVOC in older patients is therefore warranted. We, therefore, evaluated the effect of aging on the accuracy and stability of the GVOC, in determining glenoid anatomy as compared to the commonly used Scapular Border (SB) plane.MethodsComputed tomography imaging of 129 individual scapulae was obtained retrospectively from a cohort of patients who had undergone either total body or region-specific computed tomography imaging which included the shoulder region. This comprised of 35 males and 33 females (64 and 65 scapulae respectively) who were aged from 30 to 92 years. Imaging of 54 scapulae was from patients aged ≥60 years. The accuracy of the GVOC plane was then assessed against the SB plane.ResultsIn all patients, the mean difference between estimates using the GVOC plane and the GR (actual) was 2.2° (standard deviation [SD], 4.2) for version, and 1.8° (SD, 4.9) for inclination (P < .001). This contrasted with values of 7.6° (SD, 7.6) for version, and 22.9° (SD, 10.8) for inclination when using the SB reference plane (P < .001). Within the group aged ≥60 years, the mean difference between estimates using the GVOC plane and the glenoid rim (actual) was 3.2° (SD, 4.7) for version and 1.9° (SD, 3.1) for inclination, (P < .001). This contrasted to 10.0° (SD, 7.2) for version, and 23.4° (SD, 10.7) for inclination when using the SB plane (P < .001).Separately it was noted that the GVOC’s relationship to the glenoid rim remained constant throughout aging as opposed to the SB which changed significantly over time effecting estimates of glenoid retroversion.ConclusionsThe GVOC is a new plane of reference developed specifically for the use in shoulder arthroplasty. It is shown to be more accurate and stable in the aging scapulae than the currently used SB plane. The future development of guides and planning softwares that utilize the GVOC may provide an important opportunity for improved accuracy and outcome in shoulder arthroplasty.