Purpose

Total shoulder arthroplasty (TSA) has become a successful treatment option for degenerative shoulder disease. With the increasing incidence in primary TSA procedures during the last decades, strategies to improve implant longevity become more relevant. Implant failure is mainly associated with mechanical or biological causes. Chronic inflammation as a response to wear particle exposure is regarded as a main biological mechanism leading to implant failure. Metal ions released by fretting and corrosion at modular taper connections of orthopedic implants can cause cell-mediated hypersensitivity reactions and might lead to aseptic loosening. Modularity is also commonly used in total shoulder replacement. However, little is known about metal ion exposure in patients following TSA. The objective of this study was to determine in-vivo blood metal ion levels in patients after TSA and to compare blood metal ion levels to control subjects without metal implants.

Hemi shoulder arthroplasty is an attractive treatment for shoulder arthritis in particular if the natural glenoid is still intact. However, comparing the clinical results of hemi and total shoulder arthroplasty clearly shows lower survival for the hemi arthroplasty. One of the most common reasons for revision surgery is gleniod erosion, where the cartilage or bone is worn of. Aim of the current study was to analyse if the metallic articular surface of retrieved hemi shoulder arthroplasty is different from new implants. We hypothesized that the surface roughness will increased due the articulation and that metallic wear is detectable on the implants. Twelve retrieved and three brand new hemi shoulder arthroplasty were included. The surface roughness (Ra, Rz, Rmax, Rsk) was measured on different sites of the surface (center of the head and at the edge). The implants were further measured using a coordinate measuring machine to gain information on volumetric wear and geometrical alterations.

Compared to new implants the surface roughness on the retrievals was significantly increased (Tab. 1), except for skewness.

Although the roughness parameters within the retrieval group were generally higher at the center of the head compared to the edge, this difference was not significant. Apart from form deviations no volumetric wear was detectable on the heads (Fig. 1).

The current results indicate that the metallic articular implant surface changes in vivo and that the material is hurt due to the articulation against the softer cartilage or bone. Although it can't be finally clarified by that study, to what extend the higher roughness is taking part in the process of the clinically observed erosion of the gleniod, it can be assumed that an increased roughness is disadvantageous. Possibly, the observed surface alterations won't occur clinically with harder materiel (e.g. ceramic), but this even needs to be validated.

Following resection of primary malignant bone tumours of the humerus, limb salvage can be performed by vascularized fibula graft for reconstruction of large segmental defects.

In 12 patients with malignant bone tumour of the proximal humerus, tumour was resected and the bone defect reconstructed by vascularized fibula graft. Median age of the patients was 23 years. Median follow up was 114 months.

In 10 patients humeral head had to be resected and was replaced by fibular transplant including head and shaft of the ipsilateral fibula. Humeral head could be left in place in 2 patients. Median length of transplant was 17.2 cm. Radiographic union could be seen after 8 months in median. In 7 patients partial necrosis of the fibular head occurred, in 4 patients fracture of the transplant happened following trauma. In these 4 cases revision surgery was required. Partial necrosis of the head of fibula had no significant influence on shoulder function. One patient died of disease, the others are disease free. Enneking Index was 61% in median at time of last follow up. At donor side 3 cases of transient peroneal palsy could be seen.

We conclude that vascularized fibula graft is a successful surgical procedure for upper limb salvage especially for preservation of joint function also in long term follow up.