The biological response to implant-derived wear particles is recognized as one of the main factors involved in the development of periprosthetic osteolysis. Wear particles induce a foreign-body inflammatory response that results in the formation of a periprosthetic membrane and progresses over time to aseptic loosening and implant failure. Upon exposure to particles, macrophages and other cell types release inflammatory cytokines to the periprosthetic milieu such as inter-leukin-1 beta (IL-1 beta, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) which contribute to bone resorption. Heat shock proteins (HSP) are intra-cellular proteins involved in the maintenance of cellular homeostasis. The stress inducible form of the Hsp70 family protein, Hsp72, has been detected in circulation, acting as a factor capable of regulating pro-inflammatory cytokines secretion and it has been demonstrated that induces the production of pro-inflammatory cytokines via the CD14 and Toll-like receptor-mediated signal transduction pathway.

We hypothesized that Hsp72 could be involved in the inflammatory response to wear particles. To this aim, we investigated Hsp72 and its receptor, CD14, in interfacial membrane specimens obtained from patients undergoing revision surgery for aseptic loosening of uncemented acetabular cups (n=7). Distribution of both proteins was assessed by immunofluorescence and examined by confocal laser scanning microscopy. Hsp72 was detected in the periprostehetic membranes, colocalizing with CD14. Explants of membranes were cultured in vitro and levels of Hsp72 and IL-6 were determined by ELISA after 24, 48 and 72 h (n=9). Cultured membranes released IL-6 to culture medium in a time-dependent manner (p< 0.05), while Hsp72 levels decreased during same observation period (p< 0.05). These data suggest that, rather than being produced by the periprosthetic tissue, Hsp72 might be recruited by CD14+ cells from extracellular fluids. In this regard, preliminary data indicated that soluble Hsp72 levels in sera from patients undergoing revision surgery due to aseptic loosening were significantly lower than those from age-matched control subjects (n=6; p< 0.001). To investigate the involvement of Hsp72 in the inflammatory response to wear particles, we used a cell culture model of THP-1 cells driven to the monocyte/macrophage differentiation pathway. These cells were exposed to titanium particles of phagocytosable sizes, either in the presence or absence of exogenously added Hsp72. results obtained to date indicate that Hsp72 is able to modulate the titanium-induced TNF-alpha, IL-1 beta and IL-6 secretion (p< 0.05). Altogether, our data suggest that Hsp72 could be a novel mediator involved in wear particles-induced osteolysis and prosthetic failure.

Introduction and purpose: Vitamin C is essential to the synthesis of the bone’s organic matrix and a subclinical vitamin shortage has been observed in the elderly population of developed countries. The purpose of this paper is to determine whether the intake of vitamin C supplements by the elderly after sustaining a fracture improves healing.

Materials and methods: 40 1-year-old ODS rats were subjected to a usual dose of 1 gr/l of vitamin c in water for 2 weeks. Another 40 were placed on a 0.5 gr/l diet (subclinical deficit). A closed femur fracture was provoked. After the fracture, the rats were divided into two groups: the first was kept on the same diet and for the other the diet was supplemented by multiplying the vitamin C dose by two. After 5 weeks, a mechanical (torque) test was performed on the femur, and the vitamin C serum level was determined.

Results: Mechanical resistance to callus was significantly higher in the supplemented groups vis-à-vis the non-supplemented ones (p≤0.05). It was also higher in the groups with no previous deficit vis-à-vis those which had a previous deficit (p≤0.05). There was a linear correlation (p≤0.05, R=0.52) between the vitamin C levels at the time of being put down and the mechanical resistance to callus.

Conclusions and clinical relevance: In old rats, consolidation depends on the amount of vitamin C ingested during fracture consolidation. If these results were similar in elderly humans, the addition of vitamin C supplements to the diet should be indicated during consolidation.

Aims: Tension band wiring is a widely accepted method for internal þxation of olecranon fractures. Plate þxation is suggested for the more complex olecranon fractures, but little is known about the speciþc risk factors for failure of tension band wiring. The aim of this study was to analyze the inßuence of fracture comminution, associated elbow instability and fracture extension into the coronoid process on the outcome of tension band wiring for olecranon fractures. Methods: From 1996 to 1998, forty-four olecranon fractures were treated consecutively at out institution using tension band wiring. All patients returned for a clinical and radiographic exam performed by two observers independent of the treating surgeon. Pain and satisfaction were determined using visual-analogue scales (VAS) and clinical results were graded using the Mayo Elbow Performance Score (MEPS) and the DASH questionnaire. Patients were followed for 3 to 6 years. Results: At most recent follow-up, the mean VAS score for pain was 2.0, mean extension was 3.6û and mean ßexion was 137.2û. According to the MEPS the results were graded as good or excellent in 78% of the patients. Five patients were disabled for activities of daily living according to the DASH questionnaire. All but one fracture healed. Fracture comminution did not affect the outcome. Worse results were associated with elbow instability and fracture extension into the coronoid. Conclusions: Tension band wiring provided satisfactory results for the treatment of olecranon fractures in the presence of fracture comminution, but worse results were obtained in the presence of elbow instability and fracture extension into the coronoid.

Aims: internal fixation is not generally accepted as election treatment for displaced femoral neck fractures in patients older than 70. Results and risk factors are analysed in this later group of patients. Patients and Methods: 155 patients older than 70 with displaced femoral neck fractures were treated with closed reduction and parallel cannulated screws and prospectively followed for 2 years. Patients were allowed postoperative full weight bearing with aids. Quality of reduction and osteosynthesis were radiologically analysed. Results: 24 patients (15%) were lost. At the end of follow-up 52% of patients were asymptomatic, 13% had mild pain, 28% suffered a 2nd surgery (arthroplasty) and 7% were badly ill for aditional surgery. 57% presented uncomplicated consolidation, 28% non-union and 8% ischemic necrosis. Poor-quality reduction (p= 0.039) and poor-quality osteosynthesis (p=0.051) were significant risk factors for failure. A higher age (p=0.36), displacement (Eliason criteria) (p=0.26) and delay in surgery (p=0.53) were not significant risk factors. Conclusions: closed reduction and percutaneous fixation of displaced femoral neck fractures achieves good/fair results in only 65% of patients older than 70 years. Poor-quality reduction and osteosynthesis are risk factors for clinical and/or radiological failure.

Aim: To assess the long-term results of a series of porous-coated anatomic cementless total hip prostheses. Material and Methods: A total of 91 PCA (How-medica) total hip arthroplasties performed between 1984–1988 were analyzed with a mean follow-up of 13.5 years. Clinical results were assessed according to Merle DñAubignŽ-Postel score. Radiographic þxation was assessed according to Engh et al. Results:Thigh pain (17 hips) was correlated with unstable þxation (p=0.0096). Thirty-one cups and six stems were revised. Radiographic loosening ocurred in 21 cups and 12 stems. Mean polyethylene wear was 0.16 mm/year. Cup loosening was related with an acetabular wear equal to or more than 2 mm (p=0.0018) and an small cup size (p=0.015). Stem loosening was related with poor femoral canal þlling (p=0.046). Fifty (54.9%) hips had femoral osteolysis and were related with polyethylene wear of more than 2 mm (p=0.0015) and with hips with poor femoral þlling (p=0.0285) and unstable þxation (p=0.00005). Conclusions:The PCA cup has had worse results than the stem. Cup loosening is related with the acetabular wear and cup size. The frequent proximal femoral osteolysis is associated with unstable þxation and poor femoral þlling