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Biomedical subjects

R Nizard

Publications and source records attributed to R Nizard.

At least 19 recordsLinked to original sources
PubMed2006

[Femoral reconstruction with impacted macroporous calcium phosphate ceramic in revision hip arthroplasty].

PURPOSE OF THE STUDY: Management of bone stock loss remains one of the most challenging problems for revision hip surgery. The aim of this retrospective study was to report the preliminary results of peri-prosthetic femoral defect reconstruction with impacted granules of calcium phosphate ceramic. MATERIAL AND METHODS: Fourteen hips in 13 patients (3 men and 10 women) were evaluated. Age at surgery ranged from 30 to 79 years (mean 66.1 years). All revised devices had been cemented. Femoral revision was indicated for loosening in eleven hips (including six septic cases), femoral osteolysis (one hip), persistent pain (one hip), and recurrent dislocation (one hip). On the preoperative radiological evaluation, bone defects were assessed as SOFCOT grade II in seven case, and grade III in fourteen. None was rated grade IV. Once the loose prosthesis had been removed, bone graft or ceramic granules (14 cases) were firmly impacted in the femoral canal. The stem was standard and always cemented using modern cementing technique. RESULTS: At a mean follow-up of 34 +/- 15 months (range 14-76 months), eleven of fourteen hips were rated good or very good according to the Postel-Merle-d'Aubigné score. One diaphyseal femoral fracture occurred and later united. Two hips required re-revision (one aseptic femoral loosening, one septic recurrence). Direct bonding between synthetic graft and bone was observed on standard radiographs in eleven cases. Stem subsidence occurred in two cases and was limited (mean 4.5 mm). DISCUSSION: Femoral bone reconstruction using impacted calcium phosphate ceramic in revision hip arthroplasty provided encouraging results in the short to mid term. Femoral stock restoration was achieved in the great majority. No adverse effect related to the use of a synthetic graft was noted. Further long-term evaluation is required before wider application.

Adult↗
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↗
PubMed2004

[Distal femoral varus osteotomy for symptomatic genu valgum: long-term results and review of the literature].

PURPOSE OF THE STUDY: We report our experience with eleven patients treated for disabling genu valgum from 1979 to 1994. MATERIAL AND METHODS: Genu valgum resulted from femoral deformation in all patients. Ten had a congenital condition and one a post-traumatic knee. IKS scores were used for the clinical evaluation. The lateral femorotibial joint space and the lateral femoral angle (LFA) were measured on plain films. Goniometry was used to measure the axis of the loaded lower limb. All patients underwent osteotomy of the distal femur for varisation and plate fixation. One patient required revision for a unicompartment lateral prosthesis subsequent to fracture of the homolateral lateral tibial plateau. Mean follow-up was 10.5 years (3.5-21.5). RESULTS: There were no cases of nonunion. Four patients had a good or excellent knee score. Eight patients had a good or excellent function score. Osteoarthritis worsened in two patients. The mean LFA increased from 72.5 degrees preoperatively to 83.5 degrees postoperatively and a last follow-up. Mean genu valgum was 13 degrees preoperatively and 2 degrees at last follow-up. All patients except one were satisfied or very satisfied. Insufficient correction appeared to be the main complaint. DISCUSSION: These results and results reported in the literature demonstrate that distal femoral osteotomy for disabling genu valgum is an effective treatment if the correction is complete and osteosynthesis effective, providing long lasting results when femoral deformation is involved and osteoarthritis limited.

Adult↗
PubMed2004

Hybrid alumina total hip arthroplasty using a press-fit metal-backed socket in patients younger than 55 years. A six- to 11-year evaluation.

Between 1990 and 1992, we implanted 71 hybrid alumina-on-alumina hip arthroplasties in 62 consecutive patients under the age of 55 years, with a mean age of 46 years at surgery. There were 56 primary and 15 secondary procedures. The prostheses involved a cemented titanium alloy stem, a 32 mm alumina head, and a press-fit metal-backed socket with an alumina insert. Three patients (four hips) died from unrelated causes. Four hips had revision surgery for either deep infection, unexplained persistent pain, fracture of the alumina head, or aseptic loosening of the socket. The nine-year survival rate was 93.7% with revision for any cause as the end-point and 98.4% with revision for aseptic loosening as the end-point. The outcome in the surviving patients (50 patients, 57 hips) with a minimum five-year follow-up (mean eight years) was excellent in 47 hips (82.5%), very good in eight (14%), good in one and fair in one. A thin, partial, lucent line, mainly in zone III was present in 38% of the sockets and one socket had a complete lucency less than 1 mm thick. One stem had isolated femoral osteolysis. There was no detectable component migration nor acetabular osteolysis. This hybrid arthroplasty gave satisfactory medium-term results in active patients. The press-fit metal-backed socket appeared to have reliable fixation in alumina-on-alumina hip arthroplasty. The excellent results using cemented fixation of the stem may be related to the low production of wear debris.

Adult↗
PubMed2003

Disability in adults with hip and knee arthroplasty: a French national community based survey.

OBJECTIVES: To compare levels of disability of people with and without hip and knee arthroplasty in a random national sample. METHODS: In 1999 a screening questionnaire to classify people into groups of increasing probabilities of disability was sent to 417 500 people; response rate 86%. The study population was obtained by a stratified randomisation, with a high sampling rate for the most severely disabled group and a minimum sampling rate for people without daily living restrictions. A computer assisted interview to assess levels of disability, dependence, and handicap was given to 21 760 people; response rate 78%. A weighting factor was applied to obtain estimates representative of the French population. The presence of chronic conditions, impairments, and disability was ascertained from the subjects' reports. RESULTS: The hip and knee arthroplasty group comprised 815 subjects in the sample, indicating an estimated 691 000 subjects (95% confidence interval (CI) 597 000 to 785 000) in the French non-institutionalised population. The prevalence of arthroplasty is estimated at 1.2%. After adjustments for confounding factors, activity limitations were greater among subjects with arthroplasty for the following activities: climbing stairs (odds ratio (OR)=4.0, 95% CI 2.8 to 5.8); walking distance (OR=3.4, 95% CI 2.5 to 4.6 for a walking distance less than 500 m); bending forward (OR=3.2, 95% CI 2.2 to 4.7); cutting toenails (OR=2.8, 95% CI 1.9 to 3.9); carrying (OR=2.6, 95% CI= 1.8 to 3.8); shopping (OR=2.1, 95% CI 1.5 to 2.9). CONCLUSIONS: This study would be useful to policy-makers considering population strategies for managing disabling arthritis.

Activities of Daily Living↗
PubMed2003

[Surgical treatment of a femoral agenesis: a case report].

We report a case of severe femoral agenesia in an adult and propose a new surgical approach facilitating prosthesis fitting. The procedure involves insertion of a total hip arthroplasty, arthrodesis of the knee and amputation of the foot. The final prosthesis fits on the crural area with weight bearing on the ischiatic region, the lesser pelvis, and the articulated knee. Outcome was satisfactory at one year in our patient. Other surgical alternatives are presented.

Adult↗
PubMed2002

Computer assisted surgery for total knee arthroplasty.

The author has attempted to assess the value of computer-assisted surgery in arthroplasty of the knee. Basic requisites in TKR include adequate alignment and ligament balance. These requisites have become easier to meet as ancillary instrumentations have improved over time. Numerical tools are now available; they are sometimes presented as an essential technical step. The author reviews the various available options, with their advantages and disadvantages. Satisfactory alignment in the three planes classically relies on anatomic landmarks, the reliability of which is limited, and on ligament tension. Targeting systems, intra- or extramedullary, all have a margin of error. Computer-assisted surgery aims at increasing the precision of implant positioning and achieving optimal ligament balance. Among the systems currently available, a distinction must be made between active and passive systems. The former correspond to the "surgical robots", which are capable of performing the various parts of the operation following adequate preparation, at least regarding the bone cuts. Passive systems remain under control from the surgeon and assist him in positioning the cutting jigs. Among localization systems, a distinction must be made between optical and magnetic systems. Certain systems require preoperative imaging--usually CT scan--in order to first reconstruct a 3-D model of the knee. This step is time-consuming, but this will likely improve in the future. Image matching requires the use of a software, with specific landmarks defined preoperatively by the surgeon. Such systems may be used in cases with major deformities; their main drawback is the need for preoperative imaging. Other systems do not require preoperative imaging: a few points are identified by kinematic analysis of the hip, knee and ankle; they are used for 2-D or 3-D reconstruction. Computer-assisted systems may improve the precision in defining anatomic landmarks and achieving accurate location and orientation of the bone cuts, but this must still be validated. Computer-assisted surgery allows for intraoperative control of the orientation of bone cuts, the mechanical axes, the ligament balance and the range of motion. It remains to be demonstrated that using these systems will result into a clinically relevant benefit for the patient, as several of the prostheses widely implanted so far have demonstrated high survivorship rates at 15 or 20 years, so that the demonstration of a possible superiority would need considerable investment. Using these techniques does not solve all problems anyway. The patellar cut remains empirical, and these techniques also do not give any information about femoropatellar joint function. The present systems make use of the classical instrumentation, but it may be anticipated that instrumentations especially intended for computer-assisted surgery will be developed in the future. Regarding imaging, some possibilities have not yet been explored, such as plain radiography or fluoroscopy. Computer-assisted surgery should be of particular interest in revision arthroplasties, but it poses additional problem. The indications are relatively scarce however, and no major advances should be anticipated in the near future. On the whole, this is an emerging technical field. Development is slow, none of the available products is fully mature and caution is warranted in the face of enthusiastic reports and presentations. The value of computer-assisted surgery in TKR has not been demonstrated and its real usefulness still needs to be evaluated. It will, anyway, by no means exempt the surgeon from mastering the classical operative technique.

Arthroplasty, Replacement, Knee↗
PubMed2001

A discrepancy resolved: human satellite cells are not preprogrammed to fast and slow lineages.

Satellite cells from chicken and mouse muscle when differentiated in vitro have been shown to display a myosin heavy chain phenotype that corresponds to the fibre from which they originated. Indirect evidence has suggested that this might not be the case for human satellite cells. In the present study we have compared the myosin heavy chain (MHC) profile expressed by differentiated cultures of satellite cells isolated from single fast or slow muscle fibres. The MHC composition of the isolated fibres was determined by sodium dodecyl sulfate glycerol gel electrophoresis and Western blotting. The MHC profile expressed by the differentiated myotubes was identified by immunostaining using specific antibodies. Our results show that all human satellite cells isolated from either fast or slow fibres form myotubes in vitro which co-express both fast and slow MHCs independently of the fibre type from which they originated. These results confirm that human satellite cells, in contrast to those of birds and rodents, are not confined to distinct fast and slow lineages.

Adult↗
PubMed2001

Prevention of wear and osteolysis: alumina-on-alumina bearing.

Alumina-on-alumina bearings in total hip replacement have been used for 30 years. Excellent tribologic properties and extra low debris generation could, in theory, provide an answer to osteolysis. A review of the authors' experience with alumina-on-alumina bearings showed that, except in a few bearings that had been loose for a long time, osteolysis was not a problem. Although the cemented titanium stem and the alumina-on-alumina couple were not a problem, fixation of the socket had to be improved. To improve the socket fixation system and to avoid the use of a cemented titanium stem that may have created problems in the long-term, a new design was introduced in 1997. The current authors present the preliminary results of the first 96 hips with cementless fully-coated hydroxyapatite titanium alloy stems and sockets, 32-mm alumina femoral head, and alumina liner, both held with a Morse taper. Ninety-six consecutive hips in 89 patients (57 males, 32 females) with a median age of 46 years (range, 14-72 years) were analyzed. One socket was revised at 4 months because of poor primary stability in a patient with a severe acetabular fracture. One patient experienced a traumatic fracture of the implanted femur 3 weeks after surgery. The mean followup was 16 months (range, 4-38 months). One patient died from rupture of an aneurysm. Ninety-three hips in 86 patients were assessed regarding the clinical and radiologic ratings. Two patients (two hips) were interviewed by telephone. The Merle d'Aubigné rating system was 18 in 65 hips (59 patients), 17 in 25 hips (25 patients), and 16 in three hips (three patients) mainly related to a previous disability including limp, sciatic palsy, or stiffness. Examination of 93 available radiographs revealed no ostelolysis, no radiolucent lines at the last examination, and no subsidence. The level of excellent results, even in this young population, and lack of osteolysis and wear are encouraging, even if the followup is too short to allow any conclusions to be made.

Adolescent↗
PubMed2001

Hydroxyapatite-coated versus grit-blasted femoral stems. a prospective, randomised study using EBRA-FCA.

We have carried out a prospective, randomised study designed to compare the long-term stability of the stem of cementless femoral implants with differing surface configurations. A total of 50 hips (46 patients) was randomised into two groups, according to whether the medullary stem had been grit blasted (GB) or coated with hydroxyapatite (HA). Both femoral prostheses were of the same geometrical design. We used Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA) to assess the stability of the stem. The mean follow-up was for 8.66 years. The mean migration of the stem was 1.26 mm in the HA group compared with 2.57 mm in the GB group (Mann-Whitney U test, p = 0.04). A mixed model ANOVA showed that the development of subsidence was statistically different in the two groups during the first 24 months. After this subsidence increased in both groups with no difference between them. Our results indicate that, with the same design of stem, HA coating enhanced the stability of the femoral stem when compared with GB stems.

Adult↗
PubMed2001

[Impact factor or do we have to choose between the impact factor and the Revue de Chirurgie Orthopédique?].

It is common practice to evaluate the scientific value of a candidate for a university or hospital position using the mean of the impact factors of the journals he/she has published in. This shows that the true composition and true meaning of the impact factor are not sufficiently understood. The impact factor was invented in the 60s to help librarians choose the most read journals. The impact factor provides an accurate definition of the distribution of a journal, but in no case the quality of its publications. Moreover, the impact factor has many technical limitations that are detailed in this article. This strongly limits the accuracy of the impact factor to compare between journals of different specialties. There is no correlation between the scientific value of a single author and the impact factor of the journals he/she has published in. Eugene Garfield, the inventor of the impact factor, has emphasized that it should not be used to judge the scientific value of a candidate.

Abstracting and Indexing↗
PubMed2000

A clinical decision support system for prevention of venous thromboembolism: effect on physician behavior.

CONTEXT: Computer-based clinical decision support systems (CDSSs) have been promoted for their potential to improve quality of health care. However, given the limited range of clinical settings in which they have been tested, such systems must be evaluated rigorously before widespread introduction into clinical practice. OBJECTIVE: To determine whether presentation of venous thromboembolism prophylaxis guidelines using a CDSS increases the proportion of appropriate clinical practice decisions made. DESIGN: Time-series study conducted between December 1997 and July 1999. SETTING: Orthopedic surgery department of a teaching hospital in Paris, France. PARTICIPANTS: A total of 1971 patients who underwent orthopedic surgery. INTERVENTION: A CDSS designed to provide immediate information pertaining to venous thromboembolism prevention among surgical patients was integrated into daily medical practice during three 10-week intervention periods, alternated with four 10-week control periods, with a 4-week washout between each period. MAIN OUTCOME MEASURE: Proportion of appropriate prescriptions ordered for anticoagulation, according to preestablished clinical guidelines, during intervention vs control periods. RESULTS: Physicians complied with guidelines in 82.8% (95% confidence interval [CI], 77.6%-87.1%) of cases during control periods and in 94.9% (95% CI, 92.5%-96.6%) of cases during intervention periods. During each intervention period, the appropriateness of prescription increased significantly (P<.001). Each time the CDSS was removed, physician practice reverted to that observed before initiation of the intervention. The relative risk of inappropriate practice decisions during control periods vs intervention periods was 3.8 (95% CI, 2.7-5.4). CONCLUSIONS: In our study, implementation of clinical guidelines for venous thromboembolism prophylaxis through a CDSS used routinely in an orthopedic surgery department and integrated into the hospital information system changed physician behavior and improved compliance with guidelines. JAMA. 2000;283:2816-2821

Anticoagulants↗
PubMed2000

Ceramic/ceramic total hip arthroplasty.

Alumina-on-alumina total hip arthroplasty has been used for 30 years, mainly in Europe. The theoretical advantages of this combination are represented by its remarkable sliding characteristics, its very low wear debris generation, and its sufficient fracture toughness. These advantages are achieved if the material is properly controlled with high density, high purity, and small grains. The authors summarize the results obtained with ceramic/ceramic total hip arthroplasty. Information is provided about in vivo behavior regarding wear debris characterization and quantification, and histological tissue examinations for inflammatory reactions, which were not encountered except when alumina debris was mixed with metal or cement. Modification of socket fixation resulted in improved clinical outcomes. With a press-fit metal shell and an alumina liner utilized for 10 years, the results are excellent especially in a young and active population. Alumina-on-alumina seems at the moment to be one of the best choices when a total hip arthroplasty has to be performed in young and active patients.

Aluminum Oxide↗
PubMed2000

Alumina-on-alumina total hip prostheses in patients 40 years of age or younger.

To avoid the consequences of polyethylene wear in a high-risk population, 128 alumina-on-alumina total hip arthroplasties have been done in 104 consecutive patients. The maximum age of patients was 40 years. The main preoperative diagnoses were osteonecrosis and sequellae of congenital hip dislocation (71% of the hips). The same titanium alloy cemented stem was implanted in all of the hips. Four types of alumina acetabular component fixations were used: a cemented plain alumina socket (41 hips), a screw-in ring with an alumina insert (22 hips), a press-fit plain alumina socket (32 hips), and a press-fit titanium metal back with an alumina insert (33 hips). Eight patients (11 hips) died during the followup period. Sixteen revisions have been documented, 12 for acetabular aseptic loosening, three for bipolar loosening (two of which were septic), and one for unexplained pain. Eighty-eight hips in 74 patients have been followed up radiologically for 2 to 22 years. Wear was unmeasurable. Four additional sockets showed definite migration. The respective survival rates after 7 years were 94.1% for the cemented cup, 88.8% for the screw-in ring, 95.1% for cementless press-fit plain alumina socket and 94.3% for the metal-back press-fit component. The 10-year survival rate was 90.4% for the cemented socket and 88.8% for the screw-in ring. The 15-year survival rate was 78.9% for the cemented socket. Grafting was the only prognostic factor, with a survival rate of 62.6% after 10 years for the hips with a bone graft and of 90.1% for hips without a graft. The alumina-on-alumina bearing surfaces seem to be a valuable alternative to the standard metal-on-polyethylene system for young patients. However, an improvement in socket fixation is required to lengthen the life span of the prosthesis to match the life expectancy of this demanding population.

Adolescent↗
PubMed2000

Press-fit metal-backed alumina sockets: a minimum 5-year followup study.

Two hundred thirty-four consecutive alumina-on-alumina hip replacements using a press-fit metal-backed socket, performed on 214 patients (98 women, 116 men) have been reviewed. These included 201 primary procedures and 33 revision procedures. The median age of the patients at the time of surgery was 62 years (range, 21-83 years). Fourteen patients (16 hips) died from unrelated causes. Eleven patients (11 hips) underwent a total hip arthroplasty revision for recurrent dislocation (one hip), deep infection (two hips), fracture of alumina femoral head (one hip), persistent hip pain (one hip) and aseptic loosening (six hips). The survival rate after 9 years was 93.4% when revision of the prosthesis was considered the end point, and 97.4% if revision of the prosthesis for aseptic loosening was considered the end point. Results were assessed in the surviving patients with a minimal 5-year followup (170 patients, 184 hips). At the median followup of 7.8 years, the average Merle d'Aubigné and Postel score had improved from 11.9- to 17.7. Results were graded as excellent in 148 hips (80.5%), very good in 31 hips (17%), good in two hips (1%), and fair in three hips (1.5%). Radiologic data were documented for 134 patients (143 hips). Three sockets (2%) had a complete and nonprogressive radiolucent line less than 1-mm thick, one stem (0.7%) had lucencies involving five zones, and two stems (1.4%) had isolated femoral osteolysis. Neither component migration nor acetabular osteolysis were detected. A press-fit metal-backed socket may offer a good solution for alumina socket fixation when combined with a careful surgical technique of implantation.

Adult↗