Introduction: Shoulder arthroplasty in rheumatoid patients gives satisfactory pain relief and some recovery of motion. Long term complications are however frequent, such as loosening of the glenoid and rotatorcuff insufficiency. Proximal migration (PM) might be related to both these conditions, and is assumed to lead to deterioration in function and recurrence of pain.

Goal: Aim of this study was to evaluate the occurrence and identify risk factors for proximal migration after shoulder arthroplasty in a rheumatoid population.

Methods and patients: Data of 102 patients (FU 5.8 yrs) treated with a shoulder arthroplasty for rheumatoid gleno-humeral disease was analysed. Requirements were at least 3 years of follow–up and 3 follow-up moments. At each visit clinical scores and standardised radiographs were performed prospectively. Rotator-cuff status was scored per-operatively. For quantification of PM a validated measurement technique - The Spina Humeral centre method- was used. A significant decrease of the subacromial space was defined as more than two times the standard deviation of the measurement accuracy (3.65 mm).

Results: In 25 of 77 cases PM was present. PM commenced in two separate patterns, determined by the time-frame that passed before PM commenced. Early PM started directly during postoperative rehabilitation within the first two postoperative years, late PM after two years. This allowed group formation according to migration pattern; patients with no PM (PMnone), patients with late PM (PMlate) and those with early PM (PMearly). Age was higher in the PMearly group. Rotator cuff tears were more frequent and more severe in the PM groups. The ROM improved postoperatively in the PMnone and PMlate group, with deterioration of the latter in time. The HSS clinical outcome score improved in all groups.

Quality of rotator cuff repair did not alter PM outcome. PM did not occur more frequently in hemi-artho-plasty compared to total shoulder arthroplasty. A more upward oriented glenoid was observed in the PMearly and PMlate groups.

Background and purpose: The Souter-Strathclyde total elbow prosthesis is a well-studied replacement therapy for the destructed rheumatoid elbow joint. In the short-term results of a RSA-study we concluded that 8 out of 18 humeral components were at risk for loosening at two years of follow-up. Now we present the long-term results of this study to evaluate these predictions.

Patients and Methods: Twenty-one elbows (18 patients) were included in the RSA-study. At risk for loosening was defined as increase of translation of more than 0.4 mm or increase of rotation of more than one degree during the second postoperative year. The average follow-up was 98 months (range: 12–134 months). RSA-measurements were performed post-operatively, at 3 months, 6 months, 12 months and at yearly intervals thereafter. Prosthetic position and radiolucent lines (RLLs) were examined on conventional radiographs.

Results: Almost all humeral components, including the ones that were defined to be ‘at risk’ for loosening in our short-term study, showed increased and irregular migration in this long-term follow-up study. In contrast to this, the ulnar components were stable. Translations were most prominent in the posterior-anterior direction, the most prominent rotations took place about the transverse axis. No obvious influences of prosthetic alignment on micromotions were found. Four humeral components were clinically loose – three of them could be revised -, but only one of them was defined to be at risk for loosening in the short term study.

Radiological assessment based on conventional radiographs showed that a prediction of humeral loosening can be made within four years after surgery.

Interpretation: The RSA results clearly show that almost all humeral components migrate up to several millimeters and several degrees in an irregular manner, but often without clinical consequences.

Objective: Complex hand function problems in patients with rheumatic diseases may require the expertise of physicians and health professionals from multiple disciplines. The aim of the present study was to describe the characteristics, management strategies and outcomes of patients with rheumatic diseases who were referred to a multidisciplinary hand clinic.

Methods: All consecutive patients with complex hand function problems who were referred to a multidisciplinary hand clinic including a rheumatologist, an orthopaedic surgeon, a rehabilitation specialist, an occupational therapist and a physical therapist were included. Of all patients, sociodemographic characteristics, general disease characteristics, the most troubling impairments and limitations regarding hand function and deformities were recorded at baseline. The following measures of hand function were assessed at baseline and 3 months after treatment: the Sequential Occupational Dexterity Assessment (SODA), the Michigan Hand Outcomes Questionnaire (MHQ), the hand/finger function subscale of the Arthritis Impact Measurement Scales (AIMS), grip strength (Jamar dynamometer) and pain (visual analogue scale, VAS, 0–10 cm).

Results: Over a period of 28 months 69 patients were included. Basic characteristics, characteristics of hand function, impairments and limitations that were most frequently mentioned as well as the advised management strategies were recorded. In 38/54 patients (70%) the advised treatment was executed and 33 of them completed the follow-up assessment.

Conclusion: The most frequently mentioned impairments and limitations of patients with rheumatic diseases and hand function problems pertain to grip ability and grip strength, pain and shaking hands. Management advices, including conservative and surgical treatment, are followed by two-thirds of the patients. On average, patients who are treated improve significantly with respect to grip strength and overall hand function as measured by a questionnaire.

The pathology of the RAshoulder differs from that of the OA shoulder. In addition to replacement of the glenohumeral joint, procedures have to be performed to deal with disorders specific for the RA shoulder, such as bone deficiency of the glenoid, thinning or rupture of the rotator cuff, and severe internal rotation defomity. Timing of shoulder arthroplasty in the rheumatoid patient is stilla controversial issue. Clinical symptoms are more important than the radiographic destruction for timing of surgery. The status of the rotator cuff and the glenoid will predict the functional result.

Controversial issues ar whether the synovitis of the AC-joint and the subacromial area should be treated arthroscopically early to prevent destruction of the cuff, whether repair of the rotator cuff or tendon transfers effect the end result, and whether replacement of the glenoid is beneficial.

The surgical management of advanced destruction of the rheumatoid elbow differs from one center to the next, as controversy exists regarding the success of synovectomy. Total elbow arthroplasty in patients with advanced joint destruction has gained popularity. Controversial issues and new developments will be discussed.

A changed kinematic elbow axis can cause early loosening of elbow endoprostheses and can decrease the functional outcome. Therefore, these prostheses and their alignment tools are designed to reconstruct normal joint kinematics. We investigated whether it is possible to reconstruct the pre-operative kinematic axis of the elbow when an iBP^™ elbow endoprosthesis (Biomet) has been placed.

The calibrated Flock of Birds® electromagnetic tracking device registered controlled passive elbow flexion of ten embalmed upper extremities. The pre-operative kinematic elbow axes were established using helical axes.

Results were expressed in the humeral coordinate system defined by the glenohumeral joint rotation centre and the lateral and medial epicondyle of the humerus. The glenohumeral joint rotation centre was determined using a regression method. The senior author implanted the iBP^™ elbow endoprosthesis using standard instrumentation for humeral component alignment. The post-operative kinematic axes were then calculated. A Student’s t-test was performed to compare the pre- and post-operative axes.

No significant differences were found in the direction of the kinematic elbow axes before and after surgery, indicating no alteration in the valgus/varus angle or change in longitudinal rotation of the ulna with respect to the humerus. However, the axis was located significantly more distal (mean difference 7.0 mm, p = 0.004) after surgery. The ventral-dorsal location of the kinematic axis was not significantly different (p = 0.748) after surgery, but there was some variation in individual axes. The iBP^™ Elbow System enables the reconstruction of the direction of the pre-operative kinematic elbow axis. While the exact position of the pre-operative axis could not be reproduced in vitro, the kinematic axis of the elbow is expected to be less distal in vivo as a result of the extensive destruction of the rheumatoid elbow. Individually adjustable alignment tools might enable more precise reconstruction.

Early micromotion of joint prostheses with respect to the bone can be assessed very accurately by a method called Roentgen Stereophotogrammetric Analysis (RSA); a method that uses two simultaneous X-ray exposures of the joint and has an accuracy of 0.1 mm for translations and 0.3 degree for rotations [1]. In order to reach this accuracy, metallic markers are inserted into the bone and attached to the surface of the prosthesis. These markers can then be identified automatically in the two radiographs [2]. Since the adjustments to the prosthesis are difficult, time-consuming and expensive, RSA has only been applied in a limited number of clinical trials.

In a previous study we have developed a Model-based RSA algorithm, which does not require the attachment of markers to the prosthesis [3]. This algorithm is based on minimisation of the non-overlapping area (NOA) between the automatically detected contour of the prosthesis from the roentgen image, with the virtually projected contour of a three-dimensional model of the prosthesis.

Because the accuracy of this NOA algorithm was not as high as the accuracy of the currently used Marker-based RSA, we have studied alternative algorithms for Model-based RSA. From a simulation study in which we used models of the Interax Total Knee Prosthesis (Stryker-Howmedica) and the G2 Hip Prosthesis (Johnson & John-son), we found that the results of the NOA algorithm can be improved substantially. The newly developed Model-based RSA algorithm is based on minimisation of the mean distance between the points of the actual contour and the virtually projected contour. The simulation study shows that the new algorithm is superior to the NOA-algorithm in situations where part of the contour is occluded, as well as in situations where the contour is distorted by noise. With the new algorithm, the residual position error can be reduced to 0.1 mm. and also the residual orientation error can be reduced to 0.3 degree, making Model-based RSA a future alternative to Marker-based RSA.

To measure micromotion of an orthopaedic implant with respect to its surrounding bone, Roentgen Stereo-photogrammetric Analysis (RSA) was developed. A disadvantage of conventional RSA is that it requires the implant to be marked with tantalum beads. This disadvantage can potentially be resolved with model-based RSA, whereby a 3D model of the implant is used for matching with the actual images and the assessment of position and rotation of the implant. In this study, an improved model-based RSA algorithm is presented and validated in phantom experiments. This algorithm is capable to process projection contours that contain drop-outs. To investigate the influence of the accuracy of the implant models that were used for model-based RSA, we studied both Computer Aided Design (CAD) models as well as models obtained by means of Reversed Engineering (RE) of the actual implant.

The results demonstrate that the RE-models provide more accurate results than the CAD models. If these RE models are derived from the very same implant, it is possible to achieve a maximum standard deviation of the error in the migration calculation of 0.06 mm for translations in x- and y-direction and 0.14 mm for the out of plane z-direction, respectively. For rotations about the y-axis, the standard deviation was about 0.1 degree and for rotations about the x- and z-axis 0.05 degree. For the femur component, it was also possible to reach these accurate results for non-scanned components. The results show that the new algorithm is an improvement with respect to a study we presented earlier [1].

Studies with clinical RSA-radiographs must prove that these results can also be reached in a clinical setting, making model-based RSA a possible alternative for marker-based RSA.

We would like to present an overview of a research programme that aims to improve drastically the state-of-the-art in shoulder joint replacement surgery. Development of Improved endoProstheses for the upper EXtremities (DIPEX), as this effort is called, is a clinically driven multi-disciplinary programme consisting of many contributory projects. Within the project two main directions of research can be distinguished: the development of an improved shoulder prosthesis and the improvement of the surgical process. For this audience, we would like to present our approach to the improvement of the surgical process.

A newly designed visualisation platform called DSCAS (Delft Shoulder Computer Assisted Surgery) will play a central role within the DIPEX project. This platform is not only able to visualise CT and MRI datasets with a range of different algorithms, but is also able to calculate parameters that are essential for surgery and extract information from these datasets. The extracted information serves as input for the Delft Shoulder Model, an inverse dynamic musculo-skeletal finite element model, with which the effect of surgical decisions on the functional outcome, i.e. range of motion, stability of the joint etc. can be predicted and visualised.

Concerning per-operative guidance two approaches are currently studied – a camera-based approach and mechanical approach – that have both their advantages and disadvantages. Comparison of the two approaches in an experimental setting as well as in a clinical setting is part of the DIPEX project.

The ultimate goal of this part of the DIPEX project is to create a surgical support infrastructure that can be used to predict the optimal surgical protocol and can assist with the selection of the most suitable endoprosthesis for a particular patient. Subsequently, this support infrastructure must assist the surgeon during the operation in executing his surgical plan.