Kinematic 3-D motion analysis of shoulder resurfacing hemiarthroplasty - An objective assessment method.

Shoulder replacement is indicated in the treatment of pain due to osteoarthritis. Few studies have objectively assessed range of motion (RoM) gains at different post-operative time points. This is a prospective 3D motion analysis study to objectively quantify RoM changes at multiple time points following shoulder resurfacing arthroplasty (SRA) for primary gleno-humeral osteoarthritis, comparing it with clinically measured RoM. Clinical assessment, Visual Analog Scale (VAS) pain score, Constant-Morley (CS) and Oxford Shoulder Score (OSS) were recorded. Motion analysis was performed for RoM and three activities of daily living tasks (ADL), pre-operatively and post-operatively at 4 and 12 months. Nineteen shoulders in fifteen patients were included. The mean age was 72 years (range 52-84). There were significant improvements in external and internal rotation, ability to place the hand behind the head and reach the fifth lumbar vertebra, at 4 months on clinical examination and kinematic analysis with no further improvements at 12 months. There was significant improvement in abduction at 4 months with further improvement at 12 months, which was significantly more than noted on clinical assessment. In contrast, kinematic analysis showed a reduction in flexion between 4 and 12 months, while clinically there appeared to be an improvement between these time periods. This is the first study to prospectively utilise objective kinematic 3-D motion analysis in addition to clinical measurements and outcome scores, to investigate the outcome of resurfacing arthroplasty at multiple time points after surgery, providing an understanding into the trends of change in these parameters.

Position of the rotator cuff footprint in relation to the centre of rotation of the humeral head.

BACKGROUND: The objective of the present study was to determine the size and position of the rotator cuff moment arms constructed from the cuff footprints, incident on the line of force acting through the humeral head. METHODS: Five humeri were dissected, leaving the footprints of the rotator cuff intact. Each of the rotator cuff footprints and the cartilage/calcar interface were digitized and the articular surface was scanned using a high precision surface laser scanner. All of the data were merged into the same coordinate system. The centroid of each cuff footprint, centroid of the articular surface of the humerus (G) and the centroid of the articular surface of the glenoid (P) were calculated. Moment arms were measured as the intersection of a perpendicular line of force from each footprint centroid onto the resultant line of force to the centroid of the Glenoid (P). RESULTS: The mean moment arms of the supraspinatus, infraspinatus and subscapularis muscles were incident close to the centroid (G), whereas teres minor was lateral to the centroid, consistently. CONCLUSIONS: The teres minor moment arm aligned distal to the centroid of the sphere, consistently. The results may provide an understanding of the function of each muscle as a mobilizer or stabilizer of the glenohumeral joint. Further investigation is necessary.

Factors Influencing Outcome in the Management of Scaphoid Non-union and Comparison of Matti Russe and Interpositional Grafting Techniques.

BACKGROUND: Scaphoid non-union is often caused due to missed fractures, inadequate or inappropriate management. Matti-Russe and interpositional grafting techniques are used in the treatment of non-union. There are very few studies in literature that compare the outcomes of these techniques. The aim of our study was to analyse the factors influencing outcome in the management of scaphoid non-union and to compare the results of the Matti Russe procedure with interpositional grafting techniques. METHODS: Fifty scaphoid non-unions with a mean follow-up of 39.9 ± 5.5 months were included in this retrospective study. Demographic parameters, treatment, functional and radiological outcomes were recorded. The influence of demographic and treatment factors on union in this cohort was statistically analysed. RESULTS: Union was achieved in 76% of cases. Good to excellent results were achieved in 84% of patients. There was no significant difference in union rates, deformity correction achieved and period of immobilisation between the MR and IG techniques. The occurrence of arthritic changes correlated with the time interval between injury and surgery (p = 0.002). CONCLUSIONS: The most important factor that influences the outcome is the time period between the occurrence of the fracture and surgery for non-union. The Matti-Russe procedure can achieve comparable results to interpositional grafting techniques with a shorter period of immobilisation than previously thought to be required. We believe that the presence of a deformity is not a contraindication for the procedure.

Medium term outcomes of primary and revision Coonrad-Morrey total elbow replacement.

BACKGROUND: Total elbow replacement (TER) is indicated in inflammatory arthritis, osteoarthritis and fractures that are not amenable to reconstruction. There is no series in literature, to the best of our knowledge, regarding the results of revision of the Souter-Strathclyde prosthesis (SSP) to the Coonrad-Morrey prosthesis (CMP). The aim of this study is to present the medium term results of primary CMP total elbow replacement and revision of the SSP to CMP. MATERIALS AND METHODS: 50 primary CMPs (Group I) and 11 revision CMPs (Group II) were included in the study. Demographic, operative, followup and radiological data were analysed. The indication for revision of the primary implant was peri-prosthetic fracture in six cases, aseptic loosening in four cases and instability in one case. RESULTS: The mean age in Group I was 67.28 ± 12.45 years and in Group II was 57.09 ± 11.25 years. The mean period of followup was 8.08 ± 2.95 years and 7.46 ± 2.39. There was a significant improvement in range of motion and pain in both groups. The complications seen were nerve palsy, infection, fractures and heterotopic ossification. The 5-year survival rate in Group I was 94%. The results were good in 36 elbows, fair in 8 elbows and poor in 5 elbows. In Group II, the results were good in 8 elbows, fair in 2 elbows and poor in 1 elbow. The complications seen were nerve palsy, fractures and heterotopic ossification. DISCUSSION: Primary CMP TER provides a functionally useful range of movement of 100° which is enough to perform most activities of daily living. It also produces a pain free and stable joint. Similar results are achieved after revision of the SSP to CMP. The unique toggle-hinge mechanism of articulation provides inherent stability and good survivorship. CONCLUSION: Semiconstrained prostheses like CMP provide good functional results and survivorship and are the implant of choice in both primary and revision total elbow replacements.

Artroplastia reversa de ombro: avaliação radiográfica pré e pós-operatória / Reverse total shoulder arthroplasty: pre and post-operative radiographic assessment

Objetivos: Avaliar diversos parâmetros de radiografias pré e pós-operatórias de pacientes submetidos a artroplastia reversa de ombro, bem como desenvolver um método para determinar a influência desta cirurgia no centro de rotação da articulação glenoumeral. Metodologia: Análise retrospectiva do histórico médico de 22 pacientes, submetidos a artroplastia reversa de ombro. A coleta de dados incluiu sexo, idade, tempo de seguimento, lateralidade, indicação da cirurgia e achados radiológicos como notch escapular, linhas radiolucentes e o centro de rotação no pré e pós operatório. Resultados: Notch escapular foi encontrado em 3 pacientes. A presença de linhas radiolucentes no entorno do componente glenoide foi observada em 3 pacientes. Foi possível observar que o implante é eficaz no que se propõe, medializar e inferiorizar o centro de rotação. Conclusão: A principal implicação deste estudo foi o desenvolvimento de uma metodologia fácil para avaliar o centro de rotação da articulação glenoumeral no pré e pós-operatório.

Objectives: To assess pre and post-operative radiographies of patients that have been submitted to reverse total shoulder arthroplasty, and to develop a method to evaluate the influence of the reverse total shoulder arthroplasty (RTSA) in the humeral centre of rotation. Methods: A retrospective analysis of medical records from 22 patients submitted to RTSA. Data collection included demographics, surgery indication and radiological findings such as the presence of scapular notching, radiolucent lines and the pre and post-operative centre of rotation. Results: Scapular notching was found on 3 patients. The presence of radiolucent lines (RLL's) around the glenoid component was observed in 3 different patients. Only 1 case of RLL's around the humeral component was found. It observed that the RTSA successfully medializes the COR. Conclusions: Implications of this study include the fact that an easy-to-perform methodology to assess the pre and post-operative COR of the shoulder joint was developed.

A novel osteotomy in shoulder joint replacement based on analysis of the cartilage/metaphyseal interface.

BACKGROUND: The accuracy of reconstruction is thought to impact on functional outcome following glenohumeral joint arthroplasty. The objective of this study was to define an area of minimal anatomic variation at the cartilage/metaphyseal interface of the proximal humerus to optimize the osteotomy of the humeral head, enabling accurate reconstruction with a prosthetic component. METHODS: Hand held digitization and 3D surface laser scanning techniques were used to digitize 24 cadaveric arms and determine the normal geometry. Each humeral head was then examined to identify the most consistent anatomical landmarks for the ideal osteotomy plane to optimize humeral component positioning. FINDINGS: The novel, posterior referencing, osteotomy resulted in a mean increase in retroversion of only 0.4° when compared to the original geometry. A traditional anterior referencing osteotomy, by comparison, produced a mean increase in retroversion of 11°. In addition, the novel osteotomy only increased axial diameter by 0.71mm and head height by 0.02mm compared to an anterior referencing osteotomy (3.0mm and 2.7mm respectively). INTERPRETATION: The traditional osteotomy, referencing the anterior border of the cartilage/metaphyseal interface potentially resulted in an increase in prosthetic head size and retroversion. The novel osteotomy, referencing from the posterior cartilage/metaphyseal interface enabled a more accurate recovery of head geometry. Importantly, the increase in retroversion created by the traditional osteotomy was not replicated with the novel technique. Referencing from the posterior cartilage/metaphyseal interface produced a more reliable osteotomy, more closely matching the original humeral geometry. LEVEL OF EVIDENCE: Basic Science, Anatomic study, Computer model.

Important anatomical relationships of the posterior interosseous nerve in the distal forearm for surgical planning: a cadaveric study.

A thorough knowledge of the anatomy of the terminal branch of the posterior interosseous nerve (PIN) and its relationship to the anterior interosseous nerve (AIN) is essential in facilitating regional anesthetic blocks and planning surgical exposures for wrist surgery and arthrodesis of wrist and proximal row carpectomy. This cadaveric study focused on the anatomy and course of the PIN and its anatomical relationships at the distal forearm. Thirty embalmed cadaver forearms were dissected using microsurgical techniques. A structured pro forma was used to collect data. The PIN was consistently found in the fourth extensor compartment in all specimens. The last motor branch was given off 46.9 ± 8.4 mm (mean ± standard deviation) from the most proximal part of the ulnar head. The AIN was found lying consistently on the anterior aspect of the interosseous membrane, being on average 2.8 ± 0.2 mm (mean ± standard deviation) from the PIN. This knowledge will facilitate the planning of diagnostic and therapeutic procedures associated with the wrist.

Humeral head arthroplasty and its ability to restore original humeral head geometry.

BACKGROUND: Modern prosthetic components are designed to enable restoration of proximal humeral morphology, provided that a precise osteotomy of the humeral head at the level of the anatomic neck is performed. To determine whether a simulated osteotomy and replacement arthroplasty with an idealized implant were able to restore original head geometry. MATERIALS AND METHODS: A handheld digitizer and surface laser scanner were used to digitize 24 humeri. Computer models were used to simulate an osteotomy, performed at the anterior cartilage-metaphyseal interface, and reconstruct the head with a spherical prosthetic head. The head diameter, radius of curvature, and inclination and retroversion angles were calculated for each specimen and compared with the original humeral head. RESULTS: The simulated osteotomy resulted in a 4.8° decrease in inclination (P < .01) and 11.3° increase in retroversion (P < .001). The radius of curvature in the coronal plane was not significantly different (P = .284). However, in the axial plane, the prosthesis was significantly larger than the original head for both head diameter (P < .001) and radius of curvature (P < .05). DISCUSSION: The study suggests that the humeral head is not a perfect segment of a sphere and an osteotomy along the anterior cartilage-metaphyseal interface does not remove only the proximal humeral articular surface. Even with a fully adaptable prosthetic implant, replacement arthroplasty is not able to restore original head geometry. CONCLUSIONS: Alterations to head geometry with the osteotomy described may alter the line of force through the prosthetic joint, producing eccentric loading at the glenoid, and contribute to early failure.

A three-dimensional analysis of humeral head retroversion.

INTRODUCTION: The anatomic neck of the humerus is used as a reference for the osteotomy in shoulder arthroplasty. Resection along the anterior portion of the cartilage/metaphyseal border is assumed to remove a cap of a sphere that can accurately be replaced with a spherical prosthetic implant oriented precisely to the original articular surface. The aim of this study was to determine the variability in retroversion of the cartilage/metaphyseal interface in the axial plane. METHODS: Surface topography data for 24 arms from deceased donors were collected by using a hand-held digitizer and a surface laser scanner. Data were combined into the same coordinate system and graphically presented. The humeral head was divided into 6 sections in the axial plane and the retroversion angle measured at each level with reference to the transepicondylar axis at the elbow. RESULTS: The mean retroversion of the humeral head at the midpoint between the superior and inferior margins was 18.6°. The angle increased as the position of the measurement moved superiorly to 22.5°. In contrast, the retroversion angle reduced as the position of measurement moved more inferiorly to 14.3°. DISCUSSION: The results suggest that the cartilage/metaphyseal interface is not circular encompassing a spherical cap of a sphere. Furthermore, there appears to be a clockwise torsion of the cartilage/metaphyseal interface about the transverse axis from its medial to lateral aspect. CONCLUSION: The cartilage/metaphyseal interface shows a degree of variability that makes it an unreliable landmark to perform an osteotomy when the anterior aspect of the interface is used.

Automated assessment of polyethylene wear in cemented acetabular components using anteroposterior radiographs of total hip replacements.

Polyethylene wear in the acetabular components of hip prostheses is implicated in loosening and failure. Radiographic measurement of wear is used to identify patients at risk and to assess prosthesis designs. This paper focuses on analysis of prostheses with cemented acetabular cups from anteroposterior (AP) radiographs. The articular surface of the femoral head and the acetabular rim marker are modelled as spherical and circular respectively, resulting in elliptical image projections. Methods for automatically localising these structures in radiographs are presented using robust ellipse fitting and various error functions. Special attention is paid to the acetabular marker since this often projects as a highly eccentric ellipse. Robust fitting enables successful localisation in the presence of clutter without the need for user interaction. Finally, the use of these ellipses as reference structures for wear estimation is investigated and the effect of eccentricity errors is highlighted.

Learning active shape models for bifurcating contours.

Statistical shape models are often learned from examples based on landmark correspondences between annotated examples. A method is proposed for learning such models from contours with inconsistent bifurcations and loops. Automatic segmentation of tibial and femoral contours in knee X-ray images is investigated as a step towards reliable, quantitative radiographic analysis of osteoarthritis for diagnosis and assessment of progression. Results are presented using various features, the Mahalanobis distance, distance weighted K-nearest neighbours, and two relevance vector machine-based methods as quality of fit measure.

Influence of bone quality on the strength of internal and external fixation of tibial plateau fractures.

We studied the influence of different parameters of bone quality on the fixation strength of bicondylar tibial plateau fractures and examined the relationship between these parameters. Bone quality was measured in the plateau of 16 cadaveric tibias using three modalities: dual-energy X-ray absorptiometry (DXA), peripheral quantitative computer tomography (pQCT), and spectral analysis of digitized radiographs (SADR). The tibias were divided into two groups by the median bone mineral density (BMD) and randomized to receive either dual plating or external fixator for the stabilization of a standardized bicondylar tibial fracture. The fixed fractures were subjected to axial compression until failure. DXA BMD correlated most significantly with the failure load (r>or=0.79, p<0.001), followed by the pQCT parameters of cancellous bone (0.52>or=r>or=0.73, p<0.01). Similar strong correlations were also evident in both fixation methods. For parameters derived from SADR, only those including both longitudinal and transverse trabecular orientations had modest correlation with the fixation strength (0.53>or=r>or=0.71, p<0.01). The failure loads of the two fixation techniques were not significantly different (mean+/-SD=3522+/-1386 N and 3710+/-1356 N, respectively, p=0.78). However, BMD in the dual-plating group influenced the failure load significantly (p=0.03), whereas in the external fixation group this was less evident (p=0.100). The majority of bone quality parameters that correlated with fixation strength were also strongly correlated with each other, particularly the BMDs measured by DXA and pQCT. This is the first study that relates fixation strength of bicondylar tibial plateau fractures to bone quality assessed at the same anatomical site. BMD around the fracture site had the best correlation with the failure load regardless of the fixation technique. The two fixation methods tested performed equally well, and the choice between them depends on the soft tissue condition and surgeon preference.