[Metal on metal bearing surfaces in total hip arthroplasty: a survey of material incidents]. / Le frottement métal-métal en arthroplastie de hanche: aspect de matériovigilance.

This study is dedicated to the problems met with metal-metal bearing prostheses. We have analysed the results of the reports sent to the AFSSAPS relating incidents described with this interface. Only 11 incidents were reported during the last 4 years by surgeons from different centers in France. At a mean follow-up of 7 years, we collected 2614 total hip arthroplasties with metal-metal bearings and among them only 5 cases of unusual osteolysis and 10 cases of impingement. The bibliographic analysis did not show any severe specific complication due to the release of Cobalt or Chromium ions. The increased levels of Co an Cr in the patients' blood is now a well established notion (with more than 10 years follow up) and no special carcinogenetic effect has been correlated with the metal-metal bearings. Small diameter cemented cups can provide complications with high rates of acetabular loosening and metallosis; the same is true for some cementless cups also with loosening and a high revision rate. Among 143 hip prosthesis with a cemented polyethylene cup, at a mean follow-up of 42 months there were 22% of evolutive radiolucencies around the cups concerning all three De Lee and Charnley zones. Furthermore there was a statistically significant difference between small and large diameter cups (loosening of cups less than 46 mm in diameter). The same problem has been described for some cementless cups with loosening at the metal-bone interface due to a failure of osteointegration at the implant surface. However no failures were observed with an hydroxyapatite coating on the same cup. An other matter of concern is the skirted metal head: this design is responsible for a high rate of impingement and of prosthetic revision (2.3% among 642 THA). In these cases the increase of Cobalt serum levels was well correlated with the failure of the metal-metal interface. Large diameter heads decrease significantly the risks of dislocation. This is correlated with the increase in size. The release of ions in the blood was not affected by the large diameter compared to the regular size. So this overview confirms that if we respect some basic rules for the indications there are no specific complications related to the use of metal-metal bearings. In prospective studies the results of ceramic-ceramic and metal-metal bearings are similar but we must keep on observing prospectively the patients as for the release of Co and Cr.

Anomalies of the natural correction of dysplasia of the hip and treatment proposals.

The spontaneous correction of hip dysplasia occurs at every level of growth of the lower limb and it may be inadequate at any of these levels. Every abnormality of correction may induce different troubles at any level of the lower limb. A complete clinical evaluation, X-ray with different special views and CT examination is mandatory. Every deformation in any of the three spatial planes must be detected for a good understanding of the defect. The authors describe the X-ray techniques necessary for a complete evaluation of the patient and propose a CT protocol to precisely calculate the different angles of torsion of the lower limb. The possibilities of surgical treatment at different levels of the lower limb (acetabular, femoral, tibial and ankle or foot level) in DDH are pointed out to address directly the proper procedure at the correct level of the pathology.

[Carcinoma cuniculatum: an uneasy diagnosis to suspect in case of chronic osteomyelitis with unsuccessful outcome despite appropriate antibiotic therapy]. / Carcinome cuniculatum: un diagnostic difficile, à évoquer devant une ostéite chronique d'évolution défavorable sous traitement.

INTRODUCTION: The clinical and histological features of cuniculatum carcinoma (CC) are often misleading. CASE REPORT: We report a case of CC of the foot, which was misdiagnosed as osteomyelitis for a two year period and which relapsed 2 months after complete resection. DISCUSSION: The CC has to be evoked in patients with chronic osteomyelitis and torpid wound. The anatomopathologist needs to be aware of the suspected diagnosis.

Contamination by metallic elements released from joint prostheses.

When a metallic implant is in contact with human tissues, the organism reacts and a corrosion process starts. Consequently, we might observe liberation of metallic debris and wear. Our purpose is to measure the contamination and the migration of these metallic elements in the surrounding tissues of the implant. Two types of samples have been studied. First type is sample taken on post-mortem tissues around prostheses to study contamination gradients. Second type is sample taken on pathologic joints on periprosthetic capsular tissues in surgical conditions. These allow estimating contamination degree. The experiments were made on a Van de Graaff accelerator located at CERI (Centre d'Etude et de Recherche par Irradiation, Orléans, France). We measure elemental concentrations resulting from the contamination of the surface of each sample. Results are analysed in function of the pathology and the type of implants. According to the pathology and the location of the sampling, these measurements show a very heterogeneous contamination by metallic elements under particles and/or ionic species which can migrate through soft tissues by various mechanisms.

Influence of the mode of load carriage on the static posture of the pelvic girdle and the thoracic and lumbar spine in vivo.

The influence of various modes of carrying a load of 16 kg (15.69 DaN) on the static positioning of the pelvic girdle and the thoracic and lumbar segments of the spine was examined in seven male subjects. The displacement of cutaneous markers attached to easily palpable skeletal landmarks was recorded using 4 CCD cameras; the data acquired were analysed using an optoelectronic technique (SAGA3). The subjects stood upright on an AMTI biomechanical force platform, from which the ground reaction forces enabled displacements of the centre of gravity axis and thus the moment of the mass carried to be determined. The modes of load carriage examined were: 1) in a case in the left hand; 2) in a case in the right hand; 3) equally in two cases; 4) on the head; 5) in a rucksack; and 6) in an anterior bag. The results showed displacements of the pelvic girdle, the caudal and cranial lumbar segments, and the caudal and cranial thoracic segments in the three orthogonal planes (sagittal, frontal and transverse). The influence of the moment created by the load was seen in the statokinesigrams. The use of external markers using an optoelectronic technique, in association with the ground reaction forces, enables the mode of load carriage to be determined. The results show that the influence of the moment exerted by the mode of load carriage on the gravity axis has important ergonomic consequences.

Determination of metallic ion transfer from an implanted prosthesis by the PIXE method.

Prostheses can release some metallic elements to the surrounding tissues, particularly when they are not covered with a biomaterial layer and when an unsealing process happens. We try to measure major and trace elements in these tissues with an experimentally sensitive method. Proton-induced X-ray emission is used to detect about 10 elements in tissue. Tissues are calcinated and deposited in a thin layer before irradiation. Results are obtained in a standard and samples from three patients. We observe contamination by Ti, Cr, Ni, and Zn in the tissues. Correlations are to be studied between these atomic transfers and prosthesis in the patient.

Determination of the position of the pelvic girdle using surface markers.

The overall movement of the trunk is made up of two components, namely the movements of the pelvic girdle and the vertebrae. In the frontal plane, the amplitude of the pelvic movements appears to be relatively limited compared to the vertebral column whereas the pelvis makes the major contribution to the total rotational movement in the axial plane.

[Kinematics of the pelvic girdle and the thoracic and lumbar segments in the course of the lateral inclinations and rotations of the spine]. / Cinématique de la ceinture pelvienne et des segments thoracique et lombaire au cours des inclinaisons latérales et des rotations du rachis.

Physiological displacements of the trunk are the addition of these of the pelvic girdle and thoracic and lumbar spine segments. For a long time (3), this conjunction had been noticed but without numbered precisions. The purpose of this communication is to appreciate quantitatively, from a series of 16 subjects, the respective share of each components during lateral bending movements in the frontal plan and movements of rotation in the transverse plan. It results from this work that the pelvic girdle presents as reduced amplitude (4 degrees) in lateral bending on the other hand, displacement predominate to the level of thoracic spine (50 degrees). In rotation pelvic displacements are very important (30 degrees), while the spine so thoracic that lumbar has a weak participation (inferior to 5 degrees). Moderated abduction of hips increases by significant manner the motility of the pelvic girdle.

Resorption kinetics of osseous substitute: natural coral and synthetic hydroxyapatite.

Coral and hydroxyapatite may be used as substitution biomaterials for bone grafts. In this work, we extracted the implants from the femora to study the kinetics of elementary mineral transformation of the osseous substitutes. The use of physical analysis methods such as PIXE (particle-induced X-ray emission) shows that coral and hydroxyapatite, after their implantation in vivo, reach a mineral composition comparable with that of bone. For the first time we have measured the concentration of mineral elements, at different time intervals after implantation, along a cross-section. The distribution according to mineral elements (Ca, P, Sr, Zn, Fe) in the implant, in the receiver site and also at the interface, showed that the kinetics of coral resorption was faster than that of hydroxyapatite; in the same way, the osseous attack was not global but, rather, centripetal.

[The externe fixations]. / Les fixateurs externes.

The authors will highlight the advantages of external fixation in the treatment of open fractures of the leg.The first is stabilisation of the fracture site. It is obtained by using transfixion pins in multiple planes (the ideal being 2 planes between 60 and 90°). With flexible pins, stability is obtained by using multiple pins and fixing them to rings under tension.The second advantage is to allow secondary reduction and encourage consolidation by compression, distraction or dynamisation (according to Ilizarov).The third advantage is to leave the adjacent joint free which is sometimes difficult with epiphyseal and metaphyseal fractures even with the newer fixators. Preserving muscle function is sometimes difficult and depends on pin position.The fourth advantage is to be able to obtain skin cover although the use of flaps may be compromised by the pin tracks.The ideal therefore in open fractures of the leg is to fix the fracture site by pins at a distance from the fracture, to obtain skin cover after the fracture has been stabilised and then complete the assembly of the fixator.

[Open tibial fractures - The series of clermont-ferrand]. / Les fractures ouvertes de jambe - La série de Clermont-Ferrand.

The authors report a series of 9 cases over the period 1981-1992.Debridement was achieved in a single procedure in 44.5% of the cases, in 2 procedures in 33.3%, in more than 2 procedures in 22.2%. The closure of the wound was achieved by secondary sature in 77.8% of the cases and by a muscule flap in 22.2%. The fixation of the fracture was performed by an external fixator in all cases.Primary consolidation was obtained in 44.4% of the cases. A tibiofibular graft was needed in 4 cases.The mean time to consolidation was 23 months.

[Treatment of trapezius paralysis by transfer of the levator scapulae]. / Traitement de la paralysie du trapèze par transplantation de l'angulaire de l'omoplate.

The authors present a technique of palliative treatment of trapezius paralysis after injury to the spinal accessory nerve. The transfer of the levator scapulae associated, or not, with the rhomboid minor allows regression of functional signs and a return to normal function of the shoulder. Five cases are exposed, with results ranging from 3 months to 15 years.

[Tribologic study of hip prostheses]. / Etude tribologique des prothèses de hanche.

The multitude of total hip replacement systems cannot mask the fact that it is after all a matter of friction between two surfaces. The wear and distorsion resulting from this friction are still to be precisely evaluated for each marketed hip system. These two parameters have indeed to be evaluated when new devices are used. The "in vivo" behavior of a hip system is best approached when studied on a model reproducing the hip movements and the cyclic loads endured by the hip throughout walking. Data obtained using this type of model allow us to approach the behavior of metal-polyethylene interfaces: there is always a grinding period whose duration varies from 300,000 to 2,000,000 cycles. The friction factors during this initial grinding period may be two to three times greater than the final ones. Data obtained upon wear over 5 millions cycles correspond to clinical findings. Concerning the high density polyethylene-metal interface, variations of molecular size or supply of supplementary molecules may increase the friction factors up to three times the initial values. But wear may vary much more.

[Our experience with ofloxacin in the treatment of osteoarticular infections]. / Notre expérience de l'ofloxacine dans le traitement des infections ostéo-articulaires.

Twenty patients with osteoarticular infections, fourteen post-arthroplasty and six with osteitis, were treated with ofloxacin, usually in combination. Sixteen staphylococcus strains including eight aureus and eight coagulase negative (modal MIC and MBC: 0.5 micrograms/ml), three Escherichia coli (modal MIC and MBC: 0.06 micrograms/ml) and one Peptococcus (MIC: 0.25, MBC: 0.5) were isolated. Treatment was given at a mean dose of 9.81 +/- 2.46 mg/kg for a mean duration of 100 days. The serum concentration of ofloxacin was measured at 3.73 +/- 2.13 micrograms/ml for a dosage of 8.23 +/- 0.94 mg/kg (25 assays) and 7.42 +/- 4 micrograms/ml for 11.46 +/- 1.3 mg/kg (23 assays). Bacteriological control was carried out nineteen times; in one case of staphylococcal osteitis, a relapse occurred on the 43rd day of treatment when the strain isolated was resistant to ofloxacin. Three patients presented adverse effects: two cases of bone and muscle pain and one cutaneous allergic reaction: treatment was withdrawn after two restarts. The antibacterial action, the good tolerance and the easy administration of ofloxacin make it a useful antibiotic in the treatment of osteoarticular infections, where a dosage of 8 mg/kg appears to be necessary, particularly in infections due to staphylococci.

[Automatic retroversion of the femur neck during fasciculated nailing of pertrochanteric fractures by the Ender method]. / La rétroversion automatique du col fémoral lors de l'enclouage fasciculé selon Ender des fractures per-trochantériennes.

The shape of the standard Ender nail may result in malunion in external rotation in intertrochanteric fractures treated with this device. The nail is curved in one plane, and is usually introduced into the femur without making allowance for the bowing of the diaphysis and the anteversion present in the neck. We have measured radiographically the anteversion of the femoral neck in three groups of patients after operation using Ender nails, and also assessed the anteversion of the unoperated hip for comparison. In Group I normal Ender nails were used. The operated hip showed an average of 12 degrees of retroversion compared with the opposite side. In Group II the nails were bent anteriorly at their upper end, but an average retroversion of 14 degrees was produced compared with the other hip. In Group III the nails were bent to produce anterior bowing as well as proximal anteversion. The group showed retroversion of only 1 degree compared with the normal side. We therefore recommend that Ender nails be bent in this manner in order to reduce rotatory malunion when used for intertrochanteric fractures of the neck of the femur.