Development and ex-vivo assessment of a novel patient specific guide and instrumentation system for minimally invasive total shoulder arthroplasty.

Objective: To develop and assess a novel guidance technique and instrumentation system for minimally invasive short-stemmed total shoulder arthroplasty that will help to reduce the complications associated with traditional open replacement such as poor muscle healing and neurovascular injury. We have answered key questions about the developed system including (1) can novel patient-specific guides be accurately registered and used within a minimally invasive environment?; (2) can accuracy similar to traditional techniques be achieved?

Methods: A novel intra-articular patient-specific guide was developed for use with a new minimally invasive posterior surgical approach that guides bone preparation without requiring muscle resection or joint dislocation. Additionally, a novel set of instruments were developed to enable bone preparation within the minimally invasive environment.

Multiscale molecular profiling of pathological bone resolves sexually dimorphic control of extracellular matrix composition.

Collagen assembly during development is essential for successful matrix mineralisation, which determines bone quality and mechanocompetence. However, the biochemical and structural perturbations that drive pathological skeletal collagen configuration remain unclear. Deletion of vascular endothelial growth factor (VEGF; also known as VEGFA) in bone-forming osteoblasts (OBs) induces sex-specific alterations in extracellular matrix (ECM) conformation and mineralisation coupled to vascular changes, which are augmented in males.

Raman spectroscopy links differentiating osteoblast matrix signatures to pro-angiogenic potential.

Mineralization of bone is achieved by the sequential maturation of the immature amorphous calcium phase to mature hydroxyapatite (HA) and is central in the process of bone development and repair. To study normal and dysregulated mineralization in vitro, substrates are often coated with poly-l-lysine (PLL) which facilitates cell attachment. This study has used Raman spectroscopy to investigate the effect of PLL coating on osteoblast (OB) matrix composition during differentiation, with a focus on collagen specific proline and hydroxyproline and precursors of HA.

The influence of full-thickness supraspinatus tears on abduction moments: the importance of the central tendon.

Background: Detachment of the central tendon of the supraspinatus from its insertion is considered to be crucial to functional deficit. The aim of the present study was to assess the function of the supraspinatus in terms of abduction moments by introducing different tear configurations to assess the functional effect of the central tendon insertion.

Methods: Ten fresh frozen shoulders from five cadavers were prepared for testing.

Spatial mapping of humeral head bone density.

Background: Short-stem humeral replacements achieve fixation by anchoring to the metaphyseal trabecular bone. Fixing the implant in high-density bone can provide strong fixation and reduce the risk of loosening. However, there is a lack of data mapping the bone density distribution in the proximal humerus.

Rotator cuff-sparing approaches for glenohumeral joint access: an anatomic feasibility study.

Background: The deltopectoral approach for total shoulder arthroplasty can result in subscapularis dysfunction. In addition, glenoid wear is more prevalent posteriorly, a region difficult to access with this approach. We propose a posterior approach for access in total shoulder arthroplasty that uses the internervous interval between the infraspinatus and teres minor.

Assessing Performance in Shoulder Arthroscopy: The Imperial Global Arthroscopy Rating Scale (IGARS).

Background: Surgical training is undergoing major changes with reduced resident work hours and an increasing focus on patient safety and surgical aptitude. The aim of this study was to create a valid, reliable method for an assessment of arthroscopic skills that is independent of time and place and is designed for both real and simulated settings. The validity of the scale was tested using a virtual reality shoulder arthroscopy simulator.

Development and validation of a model for quantifying glenohumeral ligament strains during function.

Analysis of the function of glenohumeral ligaments (GHLs) during physical joint manipulations is hindered by an inability to adequately image these tissues during the movements. This restricts functional biomechanics studies only to the manoeuvres that may be replicated cadaverically. There is, however, a clinical imperative to be able to investigate complex manoeuvres that exacerbate symptoms but cannot be easily conducted physically in the laboratory.

Reliability of a set of protractors for direct anatomical measurements around the glenoid and humeral head rims.

Functional biomechanics studies of the glenohumeral (GH) soft tissues require an understanding of their sites of bony attachment. Anatomical positions of GH capsular structures have often been quantified relative to the rims of the glenoid and humeral head (HH). The aim of this study was twofold: (1) to quantify the reliability of a set of protractors that directly fit on to the glenoid and HH rims and (2) to use this to determine direct angular position referencing of landmarks and soft tissue attachment points.

A comparison of the degree of retraction of full-thickness supraspinatus tears with the Goutallier grading system.

Background: Tears of the supraspinatus are common and incompletely understood. The degree of fatty infiltration into the muscle is perceived to be a determining factor of successful surgical repair and postoperative function. It is the hypothesis of this study that the degree of central tendon retraction (CTR) as seen on magnetic resonance imaging corresponds to the amount of fatty infiltration classified according to the Goutallier grading system.

Rotator cuff repair failure in vivo: a radiostereometric measurement study.

Background: The prevalence of failure among repairs of the rotator cuff is well known, but very few objective data exist regarding either the scale or timing of this complication. The aim of this study was to use a previously validated modified technique of roentgen stereophotogrammetric analysis to monitor the behavior of the rotator cuff after repair to establish at what point failure may occur.

Materials And Methods: A series of 10 patients had metal beads and wire sutures embedded into the humeral greater tuberosity and supraspinatus tendon, respectively, during open cuff repair procedures.

Proximal humeral fracture classification systems revisited.

Hypothesis: This study evaluated several classification systems and expert surgeons' anatomic understanding of these complex injuries based on a consecutive series of patients. We hypothesized that current proximal humeral fracture classification systems, regardless of imaging methods, are not sufficiently reliable to aid clinical management of these injuries.

Materials And Methods: Complex fractures in 96 consecutive patients were investigated by generation of rapid sequence prototyping models from computed tomography Digital Imaging and Communications in Medicine (DICOM) imaging data.

Removal of calcific deposits of the rotator cuff tendon using an intra-articular ultrasound probe.

Calcific tendonitis is a difficult condition to treat. In this report we describe a new technique for imaging the deposit in complicated cases. Previously the patient had an unsuccessful operation due to difficulty in visualising the deposit.

A novel technique to measure active tendon forces: application to the subscapularis tendon.

This paper describes the design and use of a novel system for quantification of active tendon forces. An arthroscopically implantable force probe (AIFP) was inserted arthroscopically into the subscapularis tendon of the shoulder in vivo. The output response of this device was calibrated in situ with known forces applied to the tendon using an arthroscopic technique.

Passive tension and gap formation of rotator cuff repairs.

The objectives of this study were to quantify the relationship between passive tension of rotator cuff repairs and arm position and to examine the effect of this tension on repair gap formation. Five patients undergoing open surgical rotator cuff repair of the supraspinatus tendon were recruited. Tendon tension was recorded as the supraspinatus was advanced into a bone trough and secured.

Supraspinatus tears: propagation and strain alteration.

It was hypothesized that there would be an alteration in strain when macroscopically normal supraspinatus tendons were subjected to three patterns of surgically created tear. The propagation of joint-side partial-thickness tears was also examined. Cadaveric shoulders were tested on a purpose-built rig with static loading from 20 to 200 N and during glenohumeral abduction from 0 degrees to 120 degrees with a 100-N tensile load.

Arthroscopically insertable force probes in the rotator cuff in vivo.

In vivo loading data for the rotator cuff would be of value to scientists and clinicians interested in the shoulder. The Arthroscopically Insertable Force Probe (AIFP; Microstrain, Burlington, VT) offers a potential method for collecting this information. A technique for insertion and retrieval of the AIFP from the subscapularis is described.