Therapeutic study, Level I.

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Purpose We evaluated the risk of hypersensitivity to metals in a population of consecutive subjects undergoing a total knee arthroplasty (TKA). We also proposed a diagnostic pathway to address any sensitivity to metals. We finally presented the mid-term outcomes of a full non allergenic knee implant. Methods We developed a protocol based on the medical history, patch testing, and on specific laboratory assays, in order to assess a sensitization to metals. Twenty-four patients (25 knees) with referred or suspected allergy to metals were found in more than 1,000 treated patients, with a mean age of 72.9 years. We proceeded to a radiologic study, a clinical evaluation by the visual analogic scale (VAS), and Knee Society rating system (KSS). In all cases a full anallergic cemented implant with an oxidized zirconium femoral component and an all-polyethylene tibial baseplate was chosen. Results Four (16.6%) of the 24 patients were considered to be hypersensitive to metals. The mean follow-up was 79.2 months. No patient reported any reaction related to hypersensitivity or complications after TKA. The VAS improved from a mean preoperative value of 7.2 to 1.8 postoperatively; the KSS and the functional score increased from 38 to 91 points and from 39 to 88 points, respectively. Conclusions We consider careful research of medical history for metals hypersensitivity crucial, and we perform patch testing and lab assays in case of doubtful sensitization. The choice of a modern hypoallergenic implant may prevent any kind of potential reactions.

Purpose The purpose of our study is to describe the rationale, the surgical technique and the early clinical and radiographic results of the treatment of patients with early stage osteonecrosis of the femoral head (ONFH) by performing: core decompression, injection of autologous bone marrow concentrate and the use of a new composite injectable bone substitute (PRO-DENSE ® ), as a mechanical supplementation associated with decompression. Methods The study included 37 hips (31 patients, 14 females, 17 males; mean age 43.9 years, range 24-56 years) with stages IC-IIIA ONFH. The outcome was determined by the changes in the Harris hip score (HHS), by progression in radiographic stages and by the need for hip replacement. The mean follow-up was 20.6 months (range 12-32 months). Results At final follow-up the mean HHS increased from 68 points pre-operatively to 86 points post-operatively. The radiological results showed that 29 hips (78.4 %) improved or had no further collapse. The overall clinical success rate of the procedure was 86.5 %, with three conversions to THA, and a failure rate of only 3.3 % in the pre-collapse group. Conclusions We are encouraged by these early results using core decompression, injection of the autologous bone marrow concentrate and backfilling the defect with an injectable bioceramic for the treatment of early stages of ONFH; as far as a conclusion can be drawn from the current data, this treatment seems to relieve hip pain and prevent the progression of ONFH in the majority of the cases.

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Background Isolated acetabular revisions using standard cups are at risk of dislocation. The introduction of a nonconstrained dual-mobility cup was designed to improve prosthetic stability without increasing loosening rates, but it is unclear whether the risk of dislocation is reduced. Questions/purposes We therefore determined: (1) if the rate of dislocation in isolated acetabular revisions is lower with a dual-mobility cup, (2) implant survival, (3) patient function, and (4) radiographic incidence of migration, loosening, and osteolysis. Methods We prospectively followed 33 selected patients who underwent isolated acetabular revisions with a minimum of 2 years' followup (mean, 3 years; range, 2-5 years). In 24 patients a stainless steel dual-mobility cup was cemented into an antiprotrusio cage, whereas in nine we used a hyaluronan dual-mobility revision cup with a foramen hook and superior and posterior flanges screw fixations. We determined Harris hip (HHS) and WOMAC scores and examined radiographs for migration, loosening, and osteolysis. Results There were no dislocations. Survivorship rates of the femoral and acetabular components were 97% at 5 years; the rerevision rate for any reason was 3%. At last followup, the mean HHS increased from 48 points preoperatively to 86 points. No patients had progressive osteolysis, component migration, or loosening on radiographs. Conclusion In this select group of isolated acetabular revisions, our data suggest the use of a dual-mobility cup reduced the risk of dislocation without increasing loosening from 2 to 5 years.

Osteolysis secondary to polyethylene wear is one of the major factors limiting long-term performance of TKA. Oxidized zirconium is a new material that combines the strength of a metal with the wear properties of a ceramic. It remains unknown whether implants with a zirconium femoral component can be used safely in TKA.