V. De Santis

Reliability of the Ahlbäck classification of knee osteoarthritis

OBJECTIVE The aim of the study was to assess the inter-observer reliability and intra-observer reproducibility of the Ahlbäck radiographic classification for knee osteoarthritis (OA). DESIGN Ninety-six knee radiographs of patients with clinical signs of arthritis were evaluated and classified into five grades of Ahlbäck classification by three observers with different experience. The evaluation was repeated after 1 month. The inter- and intra-rater agreements were assessed by statistical analysis (k and k(w)coefficients). RESULTS The inter-observer agreement was statistically significant, but with low or medium values of the coefficients. The intra-rater agreement was less significant than the inter-rater. Inter- and intra-rater agreement coefficients decreased when the cases of stage V arthritis were excluded from the analysis. The evaluations were influenced by the age and working experiences of each observer. CONCLUSIONS The authors stress that the Ahlbäck classification, as routinely applied, should not be used in orthopaedic surgery without the support of clinical and/or arthroscopic examinations, because of its poor reliability.

Analysis of the Catastrophic Failure of a THR: The Role of the Acetabular Component

This paper investigates the failure of a total hip prosthesis due to the disruption of the PE inlay and the Ti-alloy metal back of the acetabular component. The PE inlay was coupled with an alumina ball head. The case analysis showed that the initiator of the failure was the size selection of the prosthesis, followed by the positioning of the acetabular component. The deformation of the PE inlay leads to rupture of the inlay itself, followed by the direct contact between the alumina ball head and the titanium alloy cup, causing the disruption of the Ti-alloy metal back, with massive release of wear debris in the surrounding tissues.

Pathophysiology of Avascular Necrosis of the Femoral Head

The interruption of arterial blood flow in the superior segment of the femoral epiphysis is a common event in pathological conditions, e.g., gas embolism in Caisson disease, traumatic vessel injuries in neck femoral fractures or hip dislocation, vascular occlusion in Gaucher’s disease, sickle cell anemia, and radiation exposure. When arterial blood impairment occurs without a documented etiology, the term idiopathic avascular necrosis must be employed.

Ceramic Total Knee Arthroplasty: Ready to Go?

Total knee arthroplasty (TKA) is a well-established surgical procedure in the late stages of knee osteoarthritis. Nevertheless, this procedure is associated with a percentage of unsatisfactory results and biomechanical failures, with aseptic loosening being the most common cause of revision. Beside these problems, cutaneous and systemic hypersensitivity reactions to metals have arisen as an increasing concern after joint arthroplasties, even if allergies against implant materials are still a quite rare and not well-known problem. Ceramic composites have been recently used in prosthetic components, showing minimum wear and excellent long-term results in total hip replacement, due to their high resistance to scratching and their better wettability with respect to cobalt–chromium alloy. Furthermore, the biologic response to debris generated from these bearings is less aggressive. Knee joint simulator tests and clinical results demonstrate promising results of TKAs with ceramic components that should led to benefit for the patients.

Ultrastructural analysis of retrieved ceramic ball heads

Surface modification of alumina heads retrieved for aseptic loosening (6 cases) has been analysed using scanning electron microscopy, coupled with energy dispersive X-ray microanalysis. Ultrastruct...

In Vivo Histological Analysis of Bone Hydroxyapatite Interface: A Case Report in a Post-Traumatic Femoral Fracture

The authors analysed the bone implant interface in a hydroxyapatite (HA) coated titanium alloy stem in a femoral fracture occurring 2 years after operation following a trauma, in the absence of any clinical symptoms of failure. A comparison between the coated and the uncoated part was made. In the coated region of the stem, connective tissue with collagen fibres perpendicularly orientated to the implant was observed, increasing stability of the system. On the contrary, in the uncoated part, fibres were orientated in parallel with less stability.