Jean Langlois

Oestrogen deficiency modulates particle-induced osteolysis

IntroductionPostmenopausal osteoporosis may modulate bone response to wear debris. In this article, we evaluate the influence of oestrogen deficiency on experimental particle-induced osteolysis.MethodsPolyethylene (PE) particles were implanted onto the calvaria of normal controls, sham-ovariectomized (OVX), OVX mice and OVX mice supplemented with oestrogen (OVX+E). After 14 days, seven skulls per group were analyzed using a high-resolution micro-computed tomography (micro-CT) and histomorphometry, and for tartrate-specific alkaline phosphatase. Five calvariae per group were cultured for the assay of IL-1β, IL-6, TNF-α and receptor activator of the nuclear factor κB (RANKL) secretion using quantitative ELISA. Serum IL-6 concentrations were obtained. The expression of RANKL and osteoprotegerin (OPG) mRNA were evaluated using real-time PCR.ResultsAs assessed by μCT and by histomorphometry, PE particles induced extensive bone resorption and an intense inflammatory reaction in normal controls, sham-OVX and OVX+E mice, but not in the OVX mice group. In normal controls, sham-OVX and OVX+E mice, PE particles induced an increase in serum IL-6, in TNF-α and RANKL local concentrations, and resulted in a significant increase in RANKL/OPG messenger RNA (mRNA) ratio. Conversely, these parameters remained unchanged in OVX mice after PE implantation.ConclusionsOestrogen privation in the osteolysis murine model ultimately attenuated osteolytic response to PE particles, suggesting a protective effect. This paradoxical phenomenon was associated with a down-regulation of pro-resorptive cytokines. It is hypothesized that excessive inflammatory response was controlled, illustrated by the absence of increase of serum IL-6 in OVX mice after PE implantation.

New animal models of wear-particle osteolysis

Particle debris resulting from in vivo degradation of total joint replacement components are recognised as the major factor limiting the longevity of joint reconstruction and the overall success of the procedure. Better understanding the complex cellular and tissue mechanisms and interactions resulting in wear-particle osteolysis requires a number of experimental approaches, including radiological monitoring and analysis of retrieved tissues from clinical cases, in vitro experiments, and also animal-model investigations. In consideration of both their advantages and drawbacks, this paper provides an historical overview of numerous animal models that have been developed over the last three decades to investigate the pathogenesis of wear-particle osteolysis and to facilitate the preclinical testing of new treatment options. The authors also focus on recent studies in order to provide a better understanding of the current state of the art on this subject and propose some perspectives regarding technical and fundamental questions.

Direct anterior Hueter approach is a safe and effective approach to perform a bipolar hemiarthroplasty for femoral neck fracture: Outcome in 82 patients

Background and purpose — The direct anterior (DA) approach in total hip arthroplasty has recently been associated with faster functional recovery than the posterolateral (PL) approach. We hypothesized that the same should hold for the DA approach in bipolar hemiarthroplasty for femoral neck fractures. Patients and methods — 82 patients with a displaced femoral neck fracture and candidates for bipolar hemiarthroplasty were enrolled after IRB approval in this prospective non-randomized comparative study (DA: n = 38; PL: n = 44). The postoperative protocols were similar in both groups. Evaluation included surgical complications, component placement, and early functional outcomes, assessed 6 weeks postoperatively using a timed up-and-go (TUG) test. The incidence of dislocation was assessed by telephone interview at least 1 year after the surgery. Results — The DA-group patients had better results in the TUG test than the PL-group patients 6 weeks after surgery: half were under 19 seconds as opposed to only one third for PL (p = 0.06). We did not record any intraoperative femoral fracture or any lateral femoral cutaneous neuropraxia in the DA group. We observed a significant difference (p = 0.04) in lateral offset between the PL group (4.2 (SD 6.4) mm) and the DA group (−1.6 (SD 8.5) mm). Stem alignment was similar between groups. The dislocation rate for DA patients was lower than for PL patients (1 of 38 cases vs. 9 of 44 cases; p = 0.02). Interpretation — Our findings indicate that relative to the posterolateral approach, the direct anterior approach for bipolar hemiarthroplasty may improve gait in the early postoperative period and decrease the dislocation rate.

Validation of a computer-assisted method for measurement of radiographic wear in total hip arthroplasty using all polyethylene cemented acetabular components

Although cemented all polyethylene (PE) cups have been routinely used in total hip arthroplasty for decades, no computer‐assisted method for measurement of radiographic wear has ever been specifically validated for these implants. Using a validated hip phantom model, AP plain hip radiographs were obtained consecutively for eight simulated wear positions. A version of Martells Hip Analysis Suite software dedicated to all polyethylene sockets was used by three different examiners of varied experience. Bias (mean, standard deviation and 95% confidence interval limit), repeatability (standard deviation and 95% limit) and reproducibility (standard deviation and 95% limit) for two‐dimensional wear measurements were assessed, as recommended by the current ASTM guidelines. Using this protocol, the dedicated software showed an overall mean bias of 0.089 ± 0.060 mm (mean ± SD), and 0.118 mm for 95% CI limit. Repeatability (intra examiner) standard deviation and 95% limit were respectively 0.106 mm and 0.292 mm. Reproducibility (inter examiner) standard deviation and 95% limit were respectively 0.112 mm and 0.308 mm. Martell Hip Analysis for all PE cemented cups is a reliable and low‐cost instrument in the assessment of wear, despite being less precise than its original version dedicated to cementless components.

Biological reaction to polyethylene particles in a murine calvarial model is highly influenced by age

Particle‐induced osteolysis is driven by multiple factors including bone metabolism, inflammation, and age. The objective of this study was to determine the influence of age on polyethylene (PE) particle‐induced osteolysis in a murine calvarial model comparing 2‐month‐old (young) versus 24‐month‐old (old) mice. After PE particle implantation, calvaria were assessed at days (D) 3, D7, D14, and D21 via chemoluminescent imaging for inflammation (L‐012 probe). In addition micro‐computed tomography (micro‐CT) and histomorphometry end points addressed the bone reaction. Inflammation peaked at D7 in young mice and D14 in old mice. Using micro‐CT, a nadir of mature bone was recorded at D7 for young mice, versus D21 for old mice. Besides, regenerating bone peaked at distinct timepoints: D7 for young mice versus D21 for old mice. In the young mice group, the histomorphometric findings correlated with micro‐CT regenerating bone findings at D7, associated with ample osteoïd deposition. No osteoïd could be histologically quantified in the old mice group at D7. This study demonstrated that the biological reaction to polyethylene particles is highly influenced by age.

Une cause inédite de luxation postopératoire précoce après reprise de prothèse totale de hanche : un œdème intracapsulaire massif par thrombose d’un filtre veineux cave inférieur

Resume Les filtres caves inferieurs sont couramment indiques dans la prevention d’embolie pulmonaire chez les patients presentant une contre-indication relative ou absolue aux anticoagulants, notamment en periode postoperatoire pour les patients de traumatologie ou apres arthroplastie prothetique de hanche ou genou. Aucune complication orthopedique specifique a ces systemes n’a ete decrite a ce jour. Nous rapportons le cas d’un patient ayant presente une decoaptation majeure de bille au sein d’une cupule prothetique mimant une luxation precoce a l’occasion d’une revision de prothese totale de hanche, en rapport avec un œdeme intra-articulaire lie a la thrombose d’un filtre cave inferieur. L’evolution a ete favorable sous traitement anticoagulant efficace. Les orthopedistes doivent penser a evaluer specifiquement en preoperatoire les patients porteurs de filtre cave, en raison du risque d’occlusion ou de migration de ces systemes, et se rappeler que les filtres doivent etre retires une fois le risque thromboembolique majeur revolu.