Acetabular bone structure is not the same in all patients and can be defined by the radiolucent triangle superior to the acetabulum. We ask if the acetabular anatomy determines the initial cup fixation and screws use. We have assessed 205 hips in which a Cerafit cementless cup was implanted. According to Dorr et al., acetabulae were classified as type A, in which the radiolucent triangle had an isosceles shape (86 hips), type B, in which the triangle extended into the teardrop (90 hips), and type C which had a right-angle triangle (29 hips). The use of screws was decided at the time of surgery and according to cup stability, not acetabular anatomy. Avascular necrosis and inflammatory arthritis were the most frequent diagnoses in type A hips, osteoarthritis in type B, and dysplasia in type C. Women were more frequent in types A and C (p<
0.001). The use of screws was more frequent in women (p<
0.001) and in type A (34.9%) and type C hips (62.1%) than in type B hips (20.0%) (p<
0.001). The multivariate logistic regression model showed the acetabular type (p=0.11) and gender (p=0.003) as independent factors. Acetabular types A (OR=1.98, 95% CI: 0.922–4.208, p=0.075) and C (OR=5.09, 95% CI: 1.74–14.9, p=0.003) increase the risk for screw use. Men have a lower risk for screw use (OR=0.329, 95% CI: 0.16–0.68, p=0.003). Acetabular anatomy and gender determine the use of screws in cementless cups. Continued follow-up is necessary to determine if screws results in less loosening and osteolysis.
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.
Cultures were polymicrobial in 22 cases and by Gram-positive in 55 (80.9%). Highly-resistant organisms: methicillin-resistant Staphylococcus (36 patients) and ESBL-producing Enterobacteriaceae (2 patients). “Problematic-treatment”: Enterococcus (6 patients), Pseudomonas (3 patients), non-fermenting Gram-negative (2), moulds (1). Oral antibiotic selection: according to bacterial sensitivity, biofilm and intracellular effectiveness. Protocolized surgery: two-stage exchange. Average follow-up: 4.7+/−2.7 years (1–11). Healing of infection is diagnosed if absence of clinical, serological and radiological signs of infection during the whole follow-up. Orthopaedic outcome is evaluated by HHS for hips and by KSCRS for knees.
Healing of infection: 59/68 patients (86.8%), 32/37 hips (86.5%) and 27/31 knees (87.1%). Infection not healed: 7/68 cases (10.3%) (4/37 hips, 3/31 knees) (5 by highly-resistant and 1 by “problematic-treatment” bacteria). There are no differences between hips and knees (p=0.55).
Statistically significant differences are not found when comparing subgroups according to Gram stain (p=0.43), multiple vs single bacteria (p=0.47 infective, p=0.71 orthopaedic), highly-resistant bacteria (p=0.2 infective, p=0.1/0.5 orthopaedic), or “problematic-treatment” (p=0.68).
A strong statistical correlation appears between infective and orthopedic results after late arthroplasty infections. With the number of cases presented significant differences in infective or in orthopaedic results are not found when comparing single vs. polymicrobial, gram-negative vs. gram-positive, high vs. low antimicrobial resistance and “problematic-treatment” infections.
Gestational age was 1st trimester (3 cases), 2nd trimester (5 cases), 3rd trimester (5 cases). 10 women were treated surgically, 8 before finishing gestation. Gestation ended as and induced abortion (3 cases, 1 due to fetal death and 2 due to teratogenic risk), and birth (10 cases, all alive, 50% eutocic). Only 3 babies needed type II or type III neonatal reanimation.
33 patients were treated from 1996 to 2002: 8 THA, 5 hip hemiarthroplasties, 20 TKA. Bacteriology: 24 Staphylococci of which 16 were methycillin-resistant, 7 multi-resistant Gram-negative, 2 Cory-nebacteriae; 7 polymicrobian. Antibiotic therapy: two simultaneous oral antibiotics, selected according to bacterial sensitivity and intracel-lular effectiveness (rifampin, ofloxacin, ciprofloxacin, levofloxacin, trimethoprim-sulfamethoxazole, fosfomicin, linezolid, doxiciclin), were used on an outpatient basis (between 1st and 2nd surgery, and after 2nd surgery until serological normalization). Patients received intravenous antibiotics and were in-hospital only for one week after surgery. Surgery: two-stage exchange with 2nd stage delayed until clinical and serological normalization. Healing of infection: absence of clinical, serological and radiological evidence of infection along all follow-up. Prospective follow-up: 24-96 months.
Treatment failure: 1 patient (TKA) (3%). THA: 8/8 infections healed: 1 Girdlestone patient (1st stage of exchange) rejected reimplantation; 7 two-stage exchange (good/excellent objective and subjective result). Hip hemiarthroplasty: 5/5 infections healed: 3 Girdlestone (1st stage of exchange surgery, 2nd stage rejected because of hemiplegia or Alzheimer); 2 two-stage exchange (good/excellent objective and subjective result). TKA: 19/20 infections healed: 3 resection-arthroplasty (1st stage of exchange surgery, 2nd stage rejected because of Buerger, cirrhosis or Alzheimer); 17 two-stage exchange (15 good/excellent objective and subjective results, 1 patient needed a debridement 2 months after 2nd surgery because of prolonged aseptic drainage and healed uneventfully, 1 failure described).