PubMed Health⌕ Search

Biomedical subjects

F Langlais

Publications and source records attributed to F Langlais.

At least 19 recordsLinked to original sources
PubMed2006

Long-term results of tendon transfers in radial and posterior interosseous nerve paralysis.

Eighteen cases of tendon transfer for isolated radial or posterior interosseous nerve palsy have been carried out in our unit over a period of 21 years. Fifteen patients were reviewed with a mean follow-up of 9.5 years. Nine had sustained high and six low radial nerve injury. We achieved 11 excellent, two good, one fair and one bad result. The main problems were loss of power of gripping and the occurrence of radial deviation, particularly in patients with flexor carpi ulnaris transfer to the extensor digitorum communis. During this time, our technique has evolved, including changes of the tendons transferred. Our final preference is a modified Tsuge procedure, using the pronator teres to restore extension of the wrist, the flexor carpi radialis for extension of the fingers and the palmaris longus for extension of the thumb. Abduction of the thumb is restored by a tenodesis of the abductor pollicis longus to the brachioradialis. This review justifies the final policy, in particular the preservation of flexor carpi ulnaris to maintain wrist stability and flexion.

Adolescent↗
PubMed2006

Antibiotic cements in articular prostheses: current orthopaedic concepts.

The possibilities and limits of antibiotic cements (ACs) have been assessed by many researchers. ACs are now approved by many drug agencies, including the US Food and Drug Administration (approval in 2003), with widespread use in prophylaxis and curative treatments. Laboratory experiments have achieved satisfactory antibiotic delivery without impairing the mechanical properties of ACs. Implantation in large animals (e.g. sheep) showed an antibiotic concentration in the bone cortex four times the minimal inhibitory concentration (MIC) 6 months after implantation. Human pharmacokinetics during total hip replacement (THR) show antibiotic concentrations 20 times the MIC in drainage fluids. No toxic concentrations have been detected in blood or urine, and no allergies, toxic effects, mechanical failures or selection of resistant microorganisms have been observed. Antibioprophylaxis has been assessed in prospective studies in over 1600 cases. In data from the Scandinavian arthroplasty registers, with an exhaustive follow-up of more than 240000 THRs, infection rate was reduced by ca. 50% (0.9% compared with 1.9%). In prostheses with severe infection, use of AC increases the infection control rate from 86% to 93% when using two-stage prosthetic exchanges. In moderate infection, a similar infection control rate (86%) was achieved either by two-stage exchange without local antibiotic or by one-stage exchange with AC; however, one-stage exchange achieved better functional results at lower cost and with reduced pain and hospital stay. Therefore, AC prophylaxis is widely used in countries with prostheses registers (Northern Europe), and use of ACs as treatment for infected prostheses is often considered as the gold standard in the EU and North America. However, AC is only an adjuvant treatment, and excision of infected and devascularized tissues as well as systemic antibiotic treatment managed by a multidisciplinary team remain the main factors of infection control.

Animals↗
PubMed2006

The long-term results of press-fit cemented stems in total knee prostheses.

We evaluated the long-term fixation of 64 press-fit cemented stems of constrained total knee prostheses in 32 young patients with primary malignant bone tumours. Initial stable fixation, especially in rotation, was achieved by precise fit of the stem into the reamed endosteum, before cementation. Complementary fixation, especially in migration and rotation, was obtained by pressurised antibiotic-loaded cement. The mean age at operation was 33 years (13 to 61). No patient was lost to follow-up; 13 patients died and the 19 survivors were examined at a mean follow-up of 12.5 years (4 to 21). Standard revision press-fit cemented stems were used on the side of the joint which was not involved with tumour (26 tibial and six femoral), on this side there was no loosening or osteolysis and stem survival was 100%. On the reconstruction side, custom-made press-fit stems were used and the survival rate, with any cause for revision as an end point, was 88%, but 97% for loosening or osteolysis. This longevity is similar to that achieved at 20 years with the Charnley-Kerboull primary total hip replacement with press-fit cemented femoral components. We recommend this type of fixation when extensive reconstruction of the knee is required. It may also be suitable for older patients requiring revision of a total knee replacement or in difficult situations such as severe deformity and complex articular fractures.

Adolescent↗
PubMed2006

[Hip dysplasia and misalignment in patients aged 20-50 years].

Anterior hip pain in young adult (20 to 50) has two main causes: secondary osteo-arthritis on development dysplasia of the hip, and femoro-acetabular impigement (FAI). This symposium had two parts: the first one analyses long-term results of non-prosthetic surgery (283 osteotomies and shelfs at 15 years FU). The second part concerned the different syndromes with acute anterior hip pain, especially due to FAI and to labral tears.In hip dysplasia, 56 shelf operations, 100 proximal femoral varus osteotomies associated or not with a shelf arthroplasty,and 127 Chiari osteotomies were examined with 10 years minimum follow-up. Only 15% of patients were lost at follow-up before 10 years and average follow-up was 15 years. Results were considered as satisfactory when the Merle d'Aubigne rating was 15/18 or more. The 3 main factors of good prognosis were: a complete correction of both femoral and acetabular dysplasia; age at operation under 40; a moderate arthritis (grade I or II according to De Mourgues and Patte). In single acetabular dysplasia with 3 favorable prognosis factors(no coxa valga, age under 40, arthritis 1 or 2), 85% good results were achieved at 15 years. When patients were over 40 at operation, or in arthritis grade over 2, only 55% of good results were observed. Varus osteotomies, associated or not with shelf arthroplasties, achieved also 85% goods results at 15 years when the 3 favorable prognosis factors were present. Similar good results were also obtained by Chiari osteotomy, but this operation was associated with 12% complications, and more that 25% of lasting limping. Therefore, with 85% good results at 15 years (and often over 20 years), non prosthetic surgery performed at 30-35 years, achieved better functional results than total hip arthroplasty, longer lasting, and not jeopardizing any further possibility of prosthetic surgery.As concerns acute anterior pain of the hip, the clinical and imaging patterns of the different syndromes have been precised: femoro-acetabular impigement by cam (or by pincer), labral tears in hip dysplasia. There were distinguished from the other secondary impigements, for example by acetabular malposition due to pelvis anteflexion or by other hip diseases: overuse arthritis, coxa retrorsa, etc. Several examples of typical syndromes were presented to support the recommended imaging techniques. The results of the speakers with different surgical treatments were reported as well as concerns open surgery than arthroscopic treatment (60 cases).

Acetabulum↗
PubMed2005

[Mid-term results of Wallaby I posterior cruciate retaining total knee arthroplasty: a prospective study of the first 425 cases].

PURPOSE OF THE STUDY: Posterior Wallaby I is a fixed polyethylene tibial plateau prosthesis enabling preservation of the posterior cruciate ligament (PCL). Its asymmetrical and divergent femoral condyles articulate with also asymmetrical tibial plateaus. The purpose of this prospective study was to analyze outcome of the first 425 Wallaby I prosthesis of the Guepar group implanted for first-intention treatment. MATERIALS AND METHODS: These 425 prostheses were implanted from December 1992 to February 1995 by senior and junior surgeons. Mean patient age at implantation was 70.5 years. 91% had primary or secondary osteoarthritis and only 8.9% had inflammatory rheumatoid disease. The mean preoperative IKS score was 25.34 points and the IKS function score was 29.04. 10.35% of knees were aligned normally (mechanical axis between 2 degrees varus and 3 degrees valgus) according to the IKS criteria (Ewald), 24% presented valgus > or = 4 degrees and 65.6% varus > or = 3 degrees. All tibial and patellar components (except one) were cemented, 5.8% of the femoral pieces were inserted without cement. All but 11 patellae were resurfaced. Clinical outcome was assessed with the IKS score and radiological outcome with the IKS criteria. The patella was considered to be tilted when the alpha angle was > 5 degrees and dislocated when the AA' distance was > 5 mm. The chi-square test was used for comparison of quantitative variables (significance set at 0.05). RESULTS: Early postoperative complications were rare: two infections cured with debridement-lavage and antibiotics without removal of the prosthesis, one peronal nerve palsy which regressed partially, ten late unions without clinical consequence (particularly in the inflammatory rheumatoid patients). Twenty-six prostheses were followed less than one year (eight patients died and eighteen were lost to follow-up) and 84 less than five years (27 patients died and 57 lost to follow-up before five years). 315 prostheses were followed for more than five years (5-9 years) with a mean follow-up of 6.3 years. Among the 399 prostheses followed for one year or more, we noted: four infections including three requiring change of the prosthesis (one cured by arthroscopic lavage), two aseptic loosenings which were revised (one global one tibial), one tibial loosening and three patellar loosenings which were not revised, and two femoral ossifications limiting joint motion but improved by arthrolysis and resection of the ossifications. Three patients experienced anterior pain requiring secondary patellar resurfacing in two and section of the lateral patellar wing in one. Ninteen patellar fractures (4.7%) were noted, including 17 with no significant functional impact which were not revised. The mean IKS knee score among prostheses followed for five years was 90.5 points, with mean motion 110.5 degrees. Mean IKS function score was 61.63 points. 72.9% of the knees were aligned, 22.2% in varus and 4.9% in valgus. The mechanical axis of 94.3% of the knees was between 5 degrees varus and 5 degrees valgus. Prosthesis survival at eight years (Kaplan-Meier method) was 97.7% considering all reasons for prosthesis removal and 98.5% for removal for aseptic loosening. CONCLUSION: This prospective multicentric study demonstrated that the results obtained with the Wallaby I prosthesis are as good as those obtained with other prostheses sparing the PCL and published in the literature. Preservation of the PCL enables better knee stability, correct motion (110.5 degrees in our series) with almost no radiological wear of the tibial polyethylene at eight years. The only worrisome complication is patellar fracture.

Adult↗
PubMed2003

Long-term results of allograft composite total hip prostheses for tumors.

The functional results of standard reconstruction prostheses are impaired by instability because of poor muscular reinsertion, especially of the gluteal muscles. In 21 patients, composite hip prostheses including proximal femoral allografts were used after primary malignant tumor resection. Ten reconstructions used combined bone-tendon allografts that allowed reinsertion of the gluteal muscles to the allograft tendons. None of the 21 patients had dislocation or infection. Ten patients died within 2 years of surgery without complications requiring reoperations. The mean followup in the 11 other patients was 10 years. Eight patients had reoperation: four for loosening (two at 3 years, two at 11 and 12 years), and four had autologous graftings for nonunion of the trochanter or of the distal graft-bone interface. Evaluation of function in the 11 patients with follow-ups ranging from 4 to 15 years showed an average Musculoskeletal Tumor Society score of 77%. Satisfactory strength of the abductor muscles was achieved by reinsertion of the trochanter or by suture of the patients gluteal muscles with the combined tendon-bone allograft. At long-term, radiologically, the bony allograft showed no change in five patients, very mild resorption in five, and severe resorption in one. Stem fixation was excellent in 10 patients and fair in one. Comparison between the functional results of reconstruction prostheses versus composite prostheses showed a significant improvement with the composite prosthesis. In the authors' institution, at 10 years, the mechanical survival of composite prostheses was 81%, as compared with only 65% for reconstruction prostheses.

Adolescent↗
PubMed2003

The 'French paradox.'.

Explore the source record for details and available documents.

Arthroplasty, Replacement, Hip↗
PubMed2003

Trochanteric slide osteotomy in revision total hip arthroplasty for loosening.

We used a trochanteric slide osteotomy (TSO) in 94 consecutive revision total hip arthroplasties (90 with replacement of both the cup and stem). This technique proved to be adequate for removing the components, with few complications (two minor fractures), and for implanting acetabular allografts (18%) and reinforcement devices (23%). Trochanteric union was obtained in most patients (96%), even in those with septic loosening (18/19), major femoral osteolysis (32/32), or previous trochanteric osteotomy (17/18). TSO is versatile, since it can be extended by a femoral flap (four cases) or a distal femoral window (eight cases). Despite significant bone loss, in 24% of the femora and 57% of the acetabula, favourable midterm results were achieved and only six reoperations were required, Including two for trochanteric nonunion and two for loosening. It leaves the lateral femoral cortex intact so that a stem longer than 200 mm was needed in only 25% of patients. This is a considerable advantage compared with the extended trochanteric osteotomy in which the long lateral flap (12 to 14 cm) requires an average length of stem of 220 mm beyond the calcar. TSO provides an approach similar in size to the standard trochanteric osteotomy but with a rate of nonunion of 4% versus 15%. It reduces the risk of difficulties with removal of the stem, and removes the need for routine distal anchoring of long revision stems. The limited distal femoral compromise is very important in patients with a long life expectancy.

Acetabulum↗
PubMed2002

[Bipolar arthroplasty in rotator cuff arthropathy: 13 cases].

PURPOSE OF THE STUDY: A series of 13 patients with an excentered osteoarthritis of the glenoid who underwent bipolar shoulder arthroplasty is reported. MATERIAL AND METHODS: The series included 13 patients treated in two centers between 1995 and 1998. Mean age was 70 years (58-88). Constant's absolute score and Swanson's score were used for clinical assessment. The Hamada and Fukuda classification was used for the radiographic assessment. The follow-up radiography series included an AP view in the three rotation positions, an AP view in maximum abduction to assess intraprosthetic mobility, a lateral view (Lamy) and measurements of both humeri. Several measurements were made to assess humerus lateralization and glenoid wear: deltoid lever arm, lateral humeral displacement, distance between the lateral border of the coracoid and the center of the glenoid and the subacromial space. Mean preoperative Constant score was 23 points: pain 3 pts, activity 5 pts, motion 13 pts, force 2 pts. Mean preoperative Swanson score was 11. Active anteflexion was 78 degrees, active abduction 68 degrees and passive external rotation 17 degrees. The Hamada and Fukuda classification was 9 grade 4 and 4 grade 5. All patients had a full thickness unrepairable rotator cuff tear: three with 2 tendon tears, and 10 with 3 tendon tears. All patients were reviewed clinically and had a complete radiography series at last follow-up (mean 28 months, range 7 - 56 months). RESULTS: At last follow-up, the mean absolute Constant score was 37 points: pain 10 pts, activity 9 pts, motion 14 pts, force 4 pts. Mean Swanson score at last follow-up was 19 points. Mean active anteflexion was 69 degrees, active abduction was 63 degrees and passive external rotation was 29 degrees. A satisfactory deltoid lever arm had been achieved compensating the glenoid wear by a greater lateral displacement of the humerus. At last follow-up, there were no cases of humeral loosening but three cases with important glenoid wear were observed after two years. Comparing the results obtained using small cups (40 and 44) with arthroplasties using large cups (48 and 52) showed a trend favoring small cups: Constant score 43 vs 32 points, Swanson score 21 versus 17 points, anteflexion 72 degrees versus 66 degrees and passive external rotation 34 degrees versus 26 degrees. DISCUSSION: Our results confirmed the efficacy of bipolar arthroplasty for pain relief, but the mobility outcome was less than satisfactory, excepting passive external rotation. It would appear to be preferable to use small cups. Comparing our results with data in the literature, particularly the better results for mobility using simple humeral prostheses, suggests that the principles of shoulder and hip arthroplasty concern different mechanisms: a sufficient deltoid lever arm must be achieved, but without overstretching the periarticular soft tissue (capsule, subcapsule, teres minor), and using a cup size close to the size of the healthy humeral head. Glenoid reaming should not be reserved only for asymmetrical glenoid wear in the horizontal plane. CONCLUSION: Our results suggest that bipolar arthroplasty for excentered osteoarthritis of the glenoid cavity is indicated for: stiffness in external rotation, major concentric wear in patients under 65 years of age, or asymmetric glenoid wear.

Aged↗
PubMed2002

[Deltoid muscle flap for massive rotator cuff tears: 41 cases with a mean 7-year (minimum 5 year) follow-up].

PURPOSE OF THE STUDY: The aim of this study was to assess outcome after deltoid muscle flap repair of massive rotator cuff tears. We examined functional and radiological results at least five years after surgery. MATERIAL AND METHODS: We reviewed 41 shoulders operated by three senior surgeons (MC, DK, HT). None of the patients were lost to follow-up. The global Constant score was used for pre- and postoperative functional assessment. Three groups were distinguished by preoperative active flexion (group I<90 degrees, group II 90 degrees -120 degrees, group III > 120 degrees ). AP, double oblique (3 rotation views to measure the subacromial space), and Lamy lateral radiographs were obtained in all patients. Shoulder anatomy was evaluated at last follow-up in eight patients: magnetic resonance imaging (MRI) because of persistent pain in one patient and ultrasonography performed by one radiologist (NC) in seven patients. RESULTS: The study population included 26 men and 15 women, mean age at surgery 59 years (42-78, 8). Mean follow-up was 7 years (5-8.5, 0.9). In the coronal plane, there were no distal tears, the stump was in an intermediate position in 7 cases (17%) and retracted to the glenoid in 34 (83%). In the sagittal plane, the supraspinatus exhibited a full thickness tear in all cases. The tear extended anteriorly or posteriorly in all cases. Thirty-eight patients (92%) were satisfied at last follow-up; their global Constant score had improved from 37 to 62 points. Mean anterior flexion improved from 113 degrees to 148 degrees and flexion force from 1.3 kg to 2.9 kg. When preoperative flexion was less than 90 degrees (11 cases), mean gain was + 89 degrees. Inversely, 7 of the 18 patients with flexion > 120 degrees lost a mean 40 degrees at last follow-up. Twenty-seven patient were reviewed at 12 and 89 months: pain relief and force were maintained. The subacromial space, measured in 88% of the cases, was 7.3 mm preoperatively and 5.5 mm at last follow-up. The subacromial space narrowed in 20 patients (56%); none of the patients exhibited an improvement. The flap was explored by ultrasonography in seven patients and by MRI in one: the flap was continuous in 50% and measured more than 4 mm in thickness. Reviews at 12 then 89 months demonstrated good maintenance of pain relief and progression of active flexion and force. DISCUSSION AND CONCLUSION: This long-term study confirms the usefulness of the deltoid flap for the treatment of full thickness massive tears of the rotator cuff. The flap provides persistent pain relief and good function and force. This technique should be discussed for young patients in good physical condition when preoperative imaging demonstrates and irreparable alteration of the tendinomuscular structures (supraspinatus retraction, fatty degeneration, severe amyotrophy). The technique is particularly useful when preoperative flexion is less than 90 degrees. Although the population size is too small for statistical analysis, indications for deltoid flap repair should probably be limited to tears involving at most two tendons and sparing the subscapularis.

Adult↗
PubMed2001

Long-term results of hemipelvis reconstruction with allografts.

Thirteen patients underwent pelvic reconstruction by massive allografts after resection of a malignant tumor (primary in 10 patients and metastatic in three patients). In 10 patients, the tumor involved the acetabulum and iliac wing and was reconstructed by a hemipelvic allograft; this was accompanied by a hip arthroplasty in nine of the patients. In three patients, a femoral metaphyseal tumor extending to the acetabulum was reconstructed by a total acetabular allograft and a composite proximal femoral allograft prosthesis. Two patients (20%) had a local recurrence, and one patient died of massive pulmonary embolism. Postoperative complications were one infection and two dislocations. At 3 years, one cup loosening and one acetabular fatigue fracture required surgery. The functional result was excellent in two patients whose gluteal muscles could be spared, good (allowing a normal family life) in six patients, fair in two patients, and poor in two patients. Seven patients had a Musculoskeletal Tumor Society rating greater than 60% of normal (the mean rating in 12 patients was 56.4%). No evidence of long-term deterioration was seen in the patients with the longest followups (7, 8, 10, and 14 years). Reconstruction of the hemipelvis with massive allografts and arthroplasty is a rewarding but demanding procedure and should be reserved for physically active patients who are in good general health and are expected to have a response to anticancer therapy. The procedure is particularly suitable for patients with primary tumors.

Acetabulum↗
PubMed1999

[Biomechanical study of the vasomotor system of the arterial smooth muscle after long-term cryopreservation of a human arterial graft at two different temperatures -80 and -150C].

We conducted two parallel studies on cryopreserved arterial homografts: a biomechanical study based on traction tests and a functional study coupled with a histology examination. Twenty-four arterial segments from 6 donors (2 iliac and 2 superficial femoral segments per donor) were cryopreserved at -150 degrees C and -80 degrees C. Cryopreservation lasted at least 6 months. Lengthening at rupture, the Young elasticity module, and rupture stress were calculated from the traction test. Results were significantly different depending on the preservation temperature. The functional properties of the cryopreserved arterial grafts were evaluated by studying the vasomotricity capacity of the vascular smooth muscle (VSM) and the endothelium. The expected results (direct contracture of VSM induced by PHE and endothelial dependent relaxation of VSM induced by ACH) were measured on fresh arteries. Cryopreserved arteries showed no response to physiological doses of PHE and ACH, whatever the preservation temperature. In one-third of the cases, a lower amplitude vasoconstriction was obtained using nonphysiological doses of PHE; there was no relaxation with ACH.

Adult↗
PubMed1998

Pharmacokinetics, uses, and limitations of vancomycin-loaded bone cement.

We have studied the mechanical and pharmacokinetic characteristics of an industrially-prepared bone cement containing 3 g of vancomycin per 60 g cement. A low viscosity cement was selected, to increase contact between the antibiotic and the infected surfaces. Resistance of compression (95 mPa) was well above the required standard (70 mPa) and similar to that of other cements with or without gentamicin. The concentrations in blood, urine and bone were measured in mg/l and mg/kg, and compared to the break point (BP) of susceptibility tests, which must be obtained to achieve control of infection. Diffusion tests were conducted in vitro (elution in saline from rods), and in 30 sheep femora implanted with the cement in vivo. In the animal study, bone levels during the first three months were three-fold higher than the BP (i.e., were > or = 12 mg/l) in 92% of specimens from all areas of bone studied and at all times since implantation; they exceeded five times the BP in 56% of specimens and were never lower than twice the BP. The mean level was four times the BP after six months and fell sharply during the next six months. A pharmacokinetic study in ten patients who had a primary total hip arthroplasty with vancomycin-loaded cement as prophylactic antibiotic therapy showed that blood levels were lower than 3 micrograms/ml, i.e., 30 times lower than the toxic threshold (90 micrograms/ml). Vancomycin was undetectable in urine after the tenth day. The levels in drainage fluids were five times the BP after 24 h and equal to it after four days. None of the ten patients treated prophylactically with vancomycin-loaded cement developed evidence of allergy, toxicity, intolerance or loosening during a two year period. No adverse events were recorded in 17 other patients treated with a vancomycin (2 g) plus gentamicin (0.8 g) loaded cement as adjuvant therapy for severe prosthetic infection.

Animals↗
PubMed1998

[Tricalcium phosphate, an antibiotic carrier: a study focused on experimental osteomyelitis in rabbits].

PURPOSE OF THE STUDY: Macroporous beta tricalcium phosphate ceramic beads were elaborated to be a resorbable bone substitute and a drug delivery system carrying gentamicin or vancomycin. The aim of this study was to evaluate this implant into a rabbit experimental osteomyelitis. MATERIAL AND METHOD: Experimentation included 24 rabbits and was performed in three stages, according to Norden's description. Induction of osteomyelitis was obtained by injection of a sclerosing agent and of Staphylococcus aureus through the lateral side of the metaphysis of the proximal tibia. Three weeks after inoculation, animals were randomly dispatched to one of the three treatment groups. After surgical debridment (to collect cinetics data), the first group received no further treatment and was considered as a control; the second group received a ceramic implant; the third group received a gentamicin-loaded ceramic implant. Euthanasia occurred between 2 days and 21 days after the debridment. Bone samples were obtained to quantify the bacterial and gentamicin bone concentrations. Gentamicin level was also measured inside the ceramic implant. Antibiotic concentration was assessed by a immunoenzymatic method. RESULTS: Osteomyelitis was obtained in 21 of the 24 animals (87.5%). Antibiotic release was early and complete (before the third day) but gentamicin still remained in the bone for 10 days. Bacterial concentration suggested an antimicrobial activity of the implant, but not a full sterilisation of the osteomyelitis. CONCLUSION: Norden's experimental osteomyelitis model with rabbit was proposed to assess the therapeutic activity of systemic antibiotics, but not to evaluate biomaterials. Therefore we have shifted for experimental evaluation of biomaterials to a metaphyseal osteomyelitis in the sheep, the patterns of which are close from those of the human disease.

Animals↗
PubMed1997

[Antibiotic release by tricalcic phosphate bone implantation. In vitro and in vivo pharmacokinetics of different galenic forms].

The purpose of this study was to evaluate the load and the release of antibiotics obtained with an implant made of a macroporous beta tricalcium phosphate ceramic (beta-TCP). Two parameters have been assessed: macroporosity and external shape (beads and parallelepipeds). In vitro, the ceramic beads were soaked in a Vancomycin-aqueous-solution, and the load of the antibiotic was then evaluated: it was 9.3% of the weight of the 40%-porosity beads and 4.6% of the weight of the 20%-porosity beads. The release has been evaluated by elution in phosphate-buffered-saline (PBS). With a 20% porosity, 12 beads (6.3 mm, 279 +/- 38 mg) demonstrated a short an massive release which ended within the 32 first hours. On the opposite, the release was sustained until the third week for the 40%-porosity beads (6.9 mm, 353 +/- 25 mg), while only one third of the load was released during the first 24 hours. A macroporosity of 40% of the ceramic could allow a deep incorporation of the antibiotic in the beads and thus decrease the rate of release. The in vivo study compared the bone concentrations of antibiotics obtained after implantations of either parallelepipedical or spherical devices in the distal femurs of 14 sheep. The bone concentrations of Gentamicin obtained with parallelepipeds until the end of the third week were from 5 to 10 times the minimum inhibitory concentration of this antibiotic for staphylococci. On the opposite, beads achieved only low concentrations of Vancomycin and nearly no detectable Gentamicin in the bone. We hypothesize a negative effect of the fibrous tissue which fills the gaps between the beads, and which could impair the diffusion of the antibiotics into the bone.

Aminoglycosides↗
PubMed1997

[Wear and loosening of prostheses].

In 1996, the outcome of any total joint replacement is loosening, occurring usually about 20 years after implantation. Loosening is not a mechanical failure of the bone-implant junction but the consequence of the osteolysis of the periprosthetic bone. It is due to an inflammatory pannus, a tissue constituted by macrophages, which are activated by wear particules originated by the articulating surfaces. The authors showed that this osteolysis is close from that observed with other inflammatory diseases and that it can be obtained with wear particules of many biomaterials, the polyethylene (PE) being the most common in clinical conditions. Several trends in order to reduce polyethylene wear or to replace PE by other materials are presented. Future improvements of the duration of joint prostheses depend on laboratories including surgeons involved in basic research: they are a mandatory link between the engineer and the biologist who study the mechanical and the biological aspects of the wear and of the fixation of biomaterials.

Friction↗