The 2021 Australian Orthopaedic Association National Joint Replacement Registry report indicated that total shoulder replacement using both mid head (TMH) length humeral components and reverse arthroplasty (RTSA) had a lower revision rate than stemmed humeral components in anatomical total shoulder arthroplasty (aTSA) - for all prosthesis types and diagnoses. The aim of this study was to assess the impact of component variables in the various primary total arthroplasty alternatives for osteoarthritis in the shoulder. Data from a large national arthroplasty registry were analysed for the period April 2004 to December 2020. The study population included all primary aTSA, RTSA, and TMH shoulder arthroplasty procedures undertaken for osteoarthritis (OA) using either cross-linked polyethylene (XLPE) or non-cross-linked polyethylene (non XLPE). Due to the previously documented and reported higher revision rate compared to other anatomical total shoulder replacement options, those using a cementless metal backed glenoid components were excluded. The rate of revision was determined by Kaplan-Meir estimates, with comparisons by Cox proportional hazard models. Reasons for revision were also assessed. For a primary diagnosis of OA, aTSA with a cemented XLPE glenoid component had the lowest revision rate with a 12-year cumulative revision rate of 4.7%, compared to aTSA with cemented non-XLPE glenoid component of 8.7%, and RTSA of 6.8%. The revision rate for TMH was lower than aTSA with cemented non-XLPE, but was similar to the other implants at the same length of follow-up. The reason for revision for cemented aTSR was most commonly component loosening, not rotator cuff deficiency. Long stem humeral components matched with XLPE in aTSA achieve a lower revision rate compared to shorter stems, long stems with conventional polyethylene, and RTSA when used to treat shoulder OA. In all these cohorts, loosening, not rotator cuff failure was the most common diagnosis for revision.
Using a reverse engineering capability to quantify the factors that control the rigid body mechanics of the wrist, a mathematical forward animation capability and model of wrist motion that allows the carpus to move under its own rules is being developed. This characterises the isometric connections, from which was developed the Stable Central Column Theory of Carpal Mechanics - which incorporates the Law of Rules Based Motion. This work has now advanced to the ability to reapply the extracted rules to allow rules-based rigid body reanimation of an individual wrist. As each wrist is unique, there is a given reality that each reanimation must be based on an individual wrist's unique rules, and the aspiration to create a standard or normal wrist is unrealistic. Using In the preliminary application of this biomechanics environment, by using the reverse engineering / forward reanimation process, wrist motion can be recreated - based purely on the unique rules, extracted from individual wrists. Instability of the proximal scaphoid was evident in several of the animations, and there was confirmation that the spatial attachment points of the isometric constraints are very exacting. The actual attachment and specific morphology of the carpal bones varied between individual wrists. Using a reverse engineering and then forward reanimation process, we have been able to recreate wrist motion using the rigid body mechanics based on the Law of Rules Based Motion. Further work is required, but the potential to apply “what if” virtual surgery options to an individual injured wrist and more precisely characterise and test solutions to wrist dysfunction are becoming realised.
Arthroscopic electrosurgical tools for ablative, desiccating or coagulative effect are delivered as monopolar or bipolar probes. Monopolar electrosurgery delivers various profiles of heat energy directly to the tissue within a non-conductive irrigant (such as water or glycine) whereas bipolar electrosurgery creates an energy source by producing an electrical arc between the bipolar electrodes on the instrument head within an electro-conductive irrigation solution (saline) - and the heat generated is then transferred to the target tissues. This study investigated the heat generation within the simulated in-vitro test model to review the level of local heat production and potential local tissue heat. In a simulated In-vitro testing environment the local heat generation using bipolar or monopolar electrosurgical probes at standard power setting in either saline or water was tested, both touching and not touching a simulated tissue target, and for variable on-times. Monopolar generated relatively little heat when used in water and not touching the tissue. By contrast the bipolar wand generated potentially damaging local tissue temperature rises when used in saline and not touching the tissue. Both probes generated high local tissue heat when touching the tissue in their recommended irrigation solution. Monopolar electrosurgery delivered high localized temperature to the simulated tissue surface, but produced relatively little heat when not touching the tissue in a water solution. Bipolar however created high local temperature within the fluid adjacent to the probe irrespective if it was touching the tissue or not. Activation of the bipolar probe away from the tissue in saline irrigation may create a potential harmful temperature within the fluid medium without delivering therapeutic thermal effect to the target tissues. Monopolar electrosurgery appears to deliver a more controlled thermal effect, and only when in contact with the target tissues – potentially creating a reduced collateral thermal footprint.
This paper presents an ongoing review of the use of a wedge-shaped porous metal augments in the shoulder to address glenoid retroversion as part of anatomical total shoulder arthroplasty (aTSA). Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42 to 85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients received either a 15º or 30º PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Standardized Shoulder Assessment Form [ASES], visual analogue scale [VAS] pain scores and forward elevation [FE]) preoperatively, at three, six, and 12 months, and yearly thereafter, with similar radiological surveillance. Forty-nine consecutive series shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24–87 months). Median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90º to 140º). Four patients died, but no others were lost to follow-up. Apart from one infection at 18 months postoperatively and one minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency or posterior re-subluxations. Radiographs showed good incorporation of the wedge augment with correction of glenoid retroversion from median 22º (13º to 46º) to 4º. All but four glenoids were corrected to within the target range (less than 10º retroversion). The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure.
Treatment strategies for the management of proximal humeral fractures are assisted by an understanding of the fracture morphology and, in particular, the viability of the humeral head. Although widely accepted, the AO and Neer classification systems show poor interobserver reproducibility and generally do not provide a basis to guide treatment. The aim of this study was to compare the interobserver and intraobserver reliability of a new classification system with the AO and Neer classifications and review its usefulness as a guide to management. Hertel described a comprehensive binary (Lego) classification system, which defines fracture planes and parts, as well as incorporating calcar length, attachment and angulation. This facilitates predicting humeral head ischemia; however the sequential numerical form of the classification makes it complex and prone to categorisation error. Sandow has extended this to a more descriptive system by naming proximal humeral parts (H-head, G-greater tuberosity, L-lesser tuberosity, S-shaft), recording the fracture plane and optionally incorporating calcar length and head angulation or displacement. 50 proximal humeral fractures in 50 patients treated at the Department of Orthopaedics and Trauma, Royal Adelaide Hospital, were identified from the period of July 2007 to January 2008. All fractures of the proximal humerus were examined using AP, lateral and axial radiographs. Three independent reviewers classified the fractures using the AO, Neer and “HGLS Classification”. The findings were analysed specifically for intra/interobserver correlation and the indications for humeral head viability. The median age of patients was 72 (range 50 to 85). Based on the interobserver correlation analysis, the AO and Neer Classification systems were graded as poor. The ‘HGLS’ Classification showed good interobserver agreement for all three examiners and more consistently provided guidelines for management based on humeral head viability. While the parts system of Neer can still provide a general impression of the fracture form, the “HGLS classification” for proximal humeral fractures provided a more precise description of the fracture pattern which has important prognostic and therapeutic implications. It is quick to apply and easy to use as it does not require memorisation of a numerical classification and can help to understand fracture patterns and thus aid planning of a reduction and fixation strategy. Good interobserver correlation makes it a useful tool for communication between surgeons.
This study has developed a unifying theory of carpal motion based on computer derived isometric constraints which guides the movement of particular bones. This extends the previously reported concept of rules based animation which proposes that resultant motion is a net interplay of bone shape, isometric constraints, bone interaction, and applied load The positional relationship between bones of the proximal row and the radius at extremes of motion was assessed to identify isometric constraints, based on a computer derived analysis rather than by observation of carpal bone motion or ligamentous anatomy. Using 3-D surface rendering software, models were created from the CT scan data of 10 normal wrists taken in extremes of radial and ulna deviation as well as flexion and extension. Virtual lines were identified between specific points of the lunate and radius which corresponded to an isometric constraint through range. Similar pairs of points were found at the trapezium and scaphoid and dorsally at the scapho-lunate joint. There was a clear discrepancy (p <
.05) between those areas (typically either volar or dorsal depending on the bones) which remain isometric and those which did not and this corresponded to previous documented anatomical structures. Variability in the pattern of isometric lines correlated with variation in scaphoid motion, thus providing a correlation with previous carpal motion observations. The Carpus can be seen to function as a stable central column (lunate/capitate/hamate/trapezoid/trapezium), with a supporting lateral column (scaphoid). This functions more as a “crossed four bar linkage” than the traditionally described “slider crank”. On the medial side of the central column, the triquetrum acts principally as an ulna translation restraint. The “trapezoid” shaped trapezoid places the trapezium anterior to the transverse plane of the radius and ulna, and thus rotates the principal axis of the central column to correspond to that used in the “Dart Thrower Motion”. This model provides a unifying theory for understanding normal and abnormal wrist motion based on isometric constraints and more broadly rules based motion. The characterisation of isometric constraints within the proximal carpal row has allowed the quantitative analysis of carpal dynamics, which has as its core, a stable central carpal column – with a lateral column stabiliser, and medial column translation restraint key to safe administration of anaesthetic in the upright position.
We prospectively compared hemiarthroplasty (HA) and total shoulder replacement (TSR) in cuff intact osteoarthritis. The 2 years postoperative review, which has been presented previously, showed an advantage of TSR over HA. This study reviewed the longer term outcome in the same patients at a minimum of 10 years to assess the longer term durability of the glenoid components. Patients with Osteoarthritis and an intact rotator cuff were intraoperatively randomisation to HA or TSR using the Global™ Shoulder Arthroplasty system after glenoid exposure. Post-operative mobilisation for the two groups was identical, and up until two years, patients were assessed using the UCLA and Constant Score, as well as analog pain scales and functional questionnaire. At the 10 year review patients were assessed using a similar range of subjective evaluations by telephone, or reviewed in the clinic as was possible Thirty-three shoulders in thirty-two patients were entered into the trial (14 HA and 19 TSR). At six months and one year, function scores and motion were similar, but the TSR group had less pain than the HA patients (p <
0.05) and this became more apparent at two years postoperatively (p<
0.02). Apart from those who died, no patients were lost to follow-up. At the two year mark postoperatively one patient in the HA group had undergone revision to TSR due to severe pain secondary to glenoid erosion, and three further HA were subsequently revised (2 at 3 years, and one at 4 years). Two shoulders in the TSR group have been revised (at 5 years and 7 years). At 10 years from the initial arthroplasty, 5 of the 14 HA and 6 of the 19 TSR had died. 10 of the 14 HA (71%) and 17 of the 19 TSR (89%) remained in situ at the time of death or at the 10 year review. Overall outcomes in each group were similar with respect to pain, function, daily activities. Based on this longer term review, our recommendation remains that TSR has advantages over HA with respect to pain and function at two years, and there has not been a reversal of the outcomes on prolonged follow-up. Revision from HA to TSR is made difficult due to glenoid erosion. Overall 89% of TSR remain insitu at death or 10 year, whereas 71% of HA were intact at the same times. The contention that HA will avoid later arthroplasty complications and, in particular, an unacceptable rate of late glenoid failure is not supported by this longer term review.
The recommended surgical treatment of osteoarthritis (OA) of the shoulder remains controversial. Recent published and presented trials evaluating hemiarthroplasty (HA) vs total shoulder arthroplasty (TSA) have been underpowered to detect a clinically relevant difference between the treatments. A meta-analysis was carried out using methodology as described by the Cochrane Collaboration. Comprehensive search strategy was used including Medline, Science Citation Index, a review of references of relevant papers and abstracts of recent orthopaedic meetings. All articles were reviewed in a blinded fashion to select qualified articles based on population, intervention, outcome and methodological rigor. 4 RCT’s were identified. One was excluded due to selection bias introduced by the timing of randomization. The data of the 3 remaining trials was combined for analysis. In each trial multiple tools were used to assess patient outcome however, the UCLA score was the only one consistent to all 3 studies. The results demonstrated a statistically significant difference in change scores from baseline to 1 year (TSA 15.6; HA 11.2, p=0.012) in favour of the total shoulder arthroplasty group. This meta analysis demonstrated that in this selected group of patients, (primary osteoarthritis with intact rotator cuff and without excessive glenoid erosion), total shoulder arthroplasty provided a more predictable improvement in pain and function than hemiarthroplasty at 2 years.
