A challenge to obtaining proper glenoid placement in total shoulder arthroplasty is eccentric posterior bone loss and associated glenoid retroversion. This bone loss can lead to poor stability and perforation of the glenoid during arthroplasty. The purpose of this study was to evaluate the three dimensional morphology of the glenoid with associated bone loss for a spectrum of osteoarthritis patients using 3-D computed tomography imaging and simulation software. This study included 29 patients with advanced glenohumeral osteoarthritis treated with shoulder arthroplasty. Three-dimensional (3D) reconstruction of preoperative CT images was performed using image analysis software. Glenoid bone loss was measured at ten, vertically equidistant axial planes along the glenoid surface at four distinct anterior-posterior points on each plane for a total of 40 measurements per glenoid. The glenoid images were also fitted with a modeled pegged glenoid implant to predict glenoid perforation.Background
Methods
Three-dimensional (3D) printing is a precise method of reproducing complex structures. Orthopaedic surgeons may utilize 3D imaging to better plan procedures, design implants, and communicate with other providers and patients. However, one of the limitations of 3D printed models has been the high cost associated with third-party creation of such tools. With the recent increases in the use of 3D printing many publically available software programs have been developed, which allow for inexpensive office-based production of models. We present a simple, inexpensive technique which can be used by surgeons for the rapid fabrication of 3D models in-office. CT scan and MRI's are stored in DICOM type format which must be transformed into a 3D image. This can be achieved using publically available programs (for example, 3D slicer (Introduction
Technique
Malposition of the glenoid component in total shoulder arthroplasty (TSA) is associated with higher strain patterns and can result in component loosening. Glenoid hardware placement and optimal size remain challenging due to the difficult joint exposure and visualization of anatomical reference landmarks during the procedure. Therefore, understanding both normal and variant patterns of glenoid anatomy is imperative for success in TSA. To better understand individual variations in glenoid morphology, this study aimed to compare the glenoid anatomy in a cohort of male and female patients from the United States (US) and Australia (AUS). Computed tomography (CT) data were analyzed from 41 male and 35 female shoulders; 39 of which were from a US population and 37 from an AUS population. These data were used to create statistical shape models (SSM) representing the average and ±1 standard deviations of the first mode of variation of each group (Materialise, Leuven, Belgium). All measurements were performed with 3-matic computer assisted design software (Materialise, Leuven, Belgium). On each model, glenoid height was measured as the distance from the most superior to the most inferior point on the glenoid face. Glenoid width was measured as the distance from the most anterior to the most posterior point on the glenoid face. Surface area was measured as the concave surface of the glenoid face (Figure 1). Glenoid vault depth was measured in the midsection of the glenoid face.Background
Methods
With growing attention being paid to quality and cost effectiveness in healthcare, outcome evaluations are becoming increasingly important. This determination can be especially difficult in reverse shoulder arthroplasty (RSA) given the complex pathology and extensive disabilities in this patient population. Several different scoring systems have been developed and validated for use in various shoulder pathologies. The purpose of this study was to assess the use three outcome scores in a population of patients undergoing RSA. We aim to demonstrate the validity of three outcome scores in patients undergoing RSA, and to determine if one score or a combination of scores is superior to others. Using a database of patients treated with RSA, we assessed preoperative and postoperative Constant Scores, American Shoulder and Elbow Surgeons (ASES) scores, and subjective shoulder values (SSV) in 148 shoulders. The outcomes at each scoring period were described and the scores were compared to one another as well as to active range of motion using linear regression modeling.Purpose
Methods
Reverse Shoulder Arthroplasty (RSA) improves the mechanics of rotator cuff deficient shoulders. To optimize functional outcomes and minimize failures of the RSA manufacturers have recently made innovative design modifications with lateralized components. However, these innovations have their own set of biomechanical trade-offs, such as increased shear forces along the glenoid bone interface. The objective of this study was to develop an efficient musculoskeletal model to evaluate and compare both the muscle forces and joint reactive force of a normal shoulder to those implanted with varied RSA implant designs. We believe these findings will provide valuable insight into possible advantages or shortcomings of this new RSA design. A kinematic model of a normal shoulder joint was adapted from publically available musculoskeletal modeling software. Static optimizations then allowed for calculation of the individual muscle forces, moment arms and joint reactive forces relative to net joint moments. An accurate 3D computer models of humeral lateralized design (HLD) (Equinoxe, Exactech, Gainesville FL, USA), glenoid lateral design (GLD) (Encore, DJO Global, Vista CA, USA), and Grammont design (GD) (Aequalis, Tornier, Amsterdam, NV) reverse shoulder prostheses was also developed and parametric studies were performed based on the numerical simulation platform.Introduction
Methods
