Laurent Hubert

Reverse shoulder arthroplasty for the treatment of three- and four-part fractures of the proximal humerus in the elderly: a prospective review of 43 cases with a short-term follow-up.

We used an inverted shoulder arthroplasty in 43 consecutive patients with a mean age of 78 years (65 to 97) who had sustained a three- or four-part fracture of the upper humerus. All except two were reviewed with a mean follow-up of 22 months (6 to 58). The clinical outcome was satisfactory with a mean active anterior elevation of 97 degrees (35 degrees to 160 degrees ) and a mean active external rotation in abduction of 30 degrees (0 degrees to 80 degrees ). The mean Constant and the mean modified Constant scores were respectively 44 (16 to 69) and 66% (25% to 97%). Complications included three patients with reflex sympathetic dystrophy, five with neurological complications, most of which resolved, and one with an anterior dislocation. Radiography showed peri-prosthetic calcification in 36 patients (90%), displacement of the tuberosities in 19 (53%) and a scapular notch in ten (25%). Compared with conventional hemiarthroplasty, satisfactory mobility was obtained despite frequent migration of the tuberosities. However, long-term results are required before reverse shoulder arthroplasty can be recommended as a routine procedure in complex fractures of the upper humerus in the elderly.

Aluminum and bone: Review of new clinical circumstances associated with Al(3+) deposition in the calcified matrix of bone.

Several decades ago, aluminum encephalopathy associated with osteomalacia has been recognized as the major complication of chronic renal failure in dialyzed patients. Removal of aluminum from the dialysate has led to a disappearance of the disease. However, aluminum deposit occurs in the hydroxyapatite of the bone matrix in some clinical circumstances that are presented in this review. We have encountered aluminum in bone in patients with an increased intestinal permeability (coeliac disease), or in the case of prolonged administration of aluminum anti-acid drugs. A colocalisation of aluminum with iron was also noted in cases of hemochromatosis and sickle cell anemia. Aluminium was also identified in a series of patients with exostosis, a frequent benign bone tumor. Corrosion of prosthetic implants composed of grade V titanium (TA6V is an alloy containing 6% aluminum and 4% vanadium) was also observed in a series of hip or knee revisions. Aluminum can be identified in undecalcified bone matrix stained by solochrome azurine, a highly specific stain allowing the detection of 0.03 atomic %. Colocalization of aluminum and iron does not seem to be the fruit of chance but the cellular and molecular mechanisms are still poorly understood. Histochemistry is superior to spectroscopic analyses (EDS and WDS in scanning electron microscopy).

Intraosseous metal implants in orthopedics: A review

Metal implants are biomaterials widely used in orthopedics. They are both used in osteosynthesis and arthroplasty. Their mechanical properties, biocompatibility and resistance to corrosion make them a widely used option in orthopedics. Alloys are the most commonly used metals in orthopedics. As far as physical traumas are concerned, implants such as screws, plates and/or nails are used for osteosynthesis as they ensure the stability of the fractured area and contribute to bone healing. Prostheses are used in arthroplasty to restore joint function for as long as possible. Contact between bone and the prosthesis induces bone remodeling at the interface between metal and bone even if the metal is recognized as biocompatible. Upon time, the interface between the metal implant and the bony tissue is continuously modified and adapted. Hip prosthesis is a typical example of intraosseous metal implant whose bone/implant interface has been extensively studied. Metal can be altered in vivo by different mechanisms including corrosion and fretting. An altered torque friction leads to wear debris that accumulate in the peri-prosthetic tissues causing metallosis.