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Biomedical subjects

J P Levai

Publications and source records attributed to J P Levai.

At least 19 recordsLinked to original sources
PubMed2003

Monitoring of polyethylene wear in nonmetal-backed acetubular cups by digitized anteroposterior pelvic radiography.

The aim of this study was to assess polyethylene wear in a total hip prosthesis by digitized radiography of the whole pelvis in the anteroposterior (AP) plane. The three-dimensional (3-D) pose of the nonmetal-backed acetubular cup, materialized by its metal ring and the femoral head made of metal or ceramic, was estimated using iterative algebraic algorithms with inner bias correction and bootstrapping for variance reduction. Points of interest were obtained by maximizing the correlation between sampled density profiles and 3-D geometric models degraded by the modulation transfer function (MTF) of the radiographic system and the film scanner. The error in the maximal correlation estimate were inferred from noise power spectra (NPS) and allowed the calculation of the point covariance matrix. Both NPS and MTF were modeled for each stage and estimated using least-square fitting of the overall NPS model to the autospectral density function calculated in stationary regions. Comparison of the radiographic time series was made possible by the high accuracy level and 3-D matching from the cup orientation. The feasibility of the full 3-D measurement, the assumption of negligible lateral wear and its influence on AP wear are discussed on simulated and real radiographic data.

Acetabulum↗
PubMed2001

Technical aspects: the patellar side.

Complications of patellar resurfacing depend largely on technique. Patellar preparation is only one element of the technique. Correct implantation can be obtained when soft tissues are equilibrated previously to sectioning, patellar cut is parallel to the prosthetic trochlea, the patellar is centered in relation to the center of the trochlea, and when thickness and height of the patella are maintained.

Arthroplasty, Replacement, Knee↗
PubMed2001

[Bone reconstruction, leg length discrepancy, and dislocation rate in 52 Wagner revision total hip arthroplasties at 44-month follow-up].

PURPOSE OF THE STUDY: The primary and secondary stability of a revision implant is highly compromised in cases with important loss of bone stock from the proximal femoral after severe femoral loosening. Several methods using implants with or without cement have been proposed for reconstruction after femoral bone loss. The purpose of this study was to analyze mid-term clinical and radiological outcome with the Wagner prosthesis for revision surgery. MATERIAL AND METHODS: Fifty-two cases of aseptic femoral loosening were treated with this method in 36 women and 14 men, mean age 70 years (range 32-92 years). None of the patients was lost to follow-up; five who died after 18 months were retained for analysis. Mean follow-up was 44 months (range 18-88 months). The mean preoperative Postel Merle d'Aubigné (PMA) score was 10.5 +/- 0.4. These patients had major bone loss (5 grade II, 24 grade III, 23 grade IV in the SOFCOT classification). The transfemoral access was used in 17 cases and bone grafts in 32. Clinical outcome was assessed with the PMA score and leg length discrepancy was measured. Radiographically, stability was assessed by measuring stem impaction and progression of radiolucent lines. RESULTS: The overall functional score was significantly improved from 10.5 +/- 0.4 preoperatively to 14.6 +/- 0.5 (p<0.001). All items on the score improved but pain relief was the most notable. Improvement in the gait score was limited due to persistent limping in 39 patients. Leg length discrepancies were found in 8 patients with 6 shortenings and 2 lengthenings. The clinical situation remained stable after one year. The implant remained stable in 48 patients (92 p. 100) and stem impaction was observed in 4 before 12 months. Two of these cases required a second revision. Metaphyseal reconstruction was observed in 42 patients (81 p. 100), including 24 (46 p. 100) who exhibited homogeneous reconstruction with trabeculation. The reconstruction did not progress further after 18 months postoperatively. Complications included four dislocations and five revision procedures (three for cup loosening, two for femoral pivot instability). DISCUSSION: The functional outcome was similar to results reported in the literature, including the high frequency of limping that was caused by various factors (valgus prosthesis neck, leg length discrepancy, muscle deficits). Leg length discrepancies resulted from defective positioning or impaction at loading. Standard radiographic series allowed an assessment of stem impaction. Our low rate could be due to delayed weight bearing. La reconstruction of bone loss did not progress after 18 months and was independent of bone grafting, route of access, and the initial degree of loosening. The high frequency of dislocations with this type of implant can be prevented by horizontalization of the acetabulum and use of anti-dislocation inserts at the first intention revision. CONCLUSION: Our results with the Wagner prosthesis are satisfactory both clinically and radiographically. The two drawbacks of this implant (limping and dislocation), partly due to the design of the femoral stem, have led us to study a new implant that preserves good distal anchoring and optimizes the proximal biomechanics of the hip joint.

Adult↗
PubMed2000

Intraosseous xanthoma without lipid disorders. Case-report and literature review.

A case of intraosseous xanthoma in a patient with a normal lipid profile is reported. Hyperlipidemia is present in most patients with xanthomas. Intraosseous xanthomas are rare, particularly in normolipidemic patients, in whom the presenting symptom is pain without skin lesions. A lytic lesion with a rim of sclerosis is seen on radiographs. Histology shows foam cells, giant cells, and fibrosis. Intraosseous xanthoma is a benign tumor, and other diagnoses must be ruled out (histiocytosis X, Erdheim Chester disease, clear cell carcinoma metastasis). Surgical excision of the lesion is the elective treatment.

Adult↗
PubMed1999

Study of the variations in length of the anterior cruciate ligament during flexion of the knee: use of a 3D model reconstructed from MRI sections.

The aim of this study is to suggest an anatomic study of the modifications of the length of the anterior cruciate ligament (ACL) and its bundles during flexion with the aid of a 3D computerized model of the knee in a living subject. The method of evaluation suggested is a 3D computerized reconstruction based on MRI sections, reproducing the movement of flexion of the knee from 0 to 75 degrees. Twenty-one sections were made for each of the 13 positions of flexion. The reconstruction of Delaunay and the realignment of each position provided a 3D model which allowed monitoring of a bony point during the movement. By knowing the relative displacement of the ligamentous attachments it was possible to define the biometry of the ligament by calculating the length of the bundles of the ACL in each position and to demonstrate the variations in length during the movement. The mean length of the ligament was 3.4 mm. The anteromedial bundle was longer by 30% compared with the other two bundles. During flexion the anteromedial bundle was not much modified (this feature seems to provide a reference position for a ligamentoplasty), the posterolateral bundle became taut after 30 degrees, and the intermediate bundle relaxed from the beginning of movement. Based on the data from the literature, this method allows an anatomic approach to the ACL, bundle by bundle, during flexion movement.

Anterior Cruciate Ligament↗
PubMed1999

[Study of the posterior cruciate ligament using a 3D computer model: ligament biometry during flexion, application to surgical replacement of the ligament].

We have developed a 3D computed model of the knee joint, constructed from MRI acquisitions in a living individual. We have used this model to perform an anatomic and biometric study of the posterior cruciate ligament (PCL) during flexion, and an assessment of the optimal location for an intraarticular graft. The method used a 3D computed model constructed from MRI acquisitions during knee flexion (0 to 75 degrees). The range of motion was limited by a positioning device. We took 13 acquisitions from 0 to 75 degrees of flexion. Each acquisition consisted of 21 sagittal cross sections of 3 mm slice thickness. We used the Delaunay reconstruction to obtain a 3D geometric model. A matching process to fix one part of the articulation during the movement, allows for the kinematic analysis of the tibia relative to the fixed femur. This model allows to follow the displacement of a bone point during knee flexion. Knowing the relative displacement of the bone insertions of the ligament, it may be possible to determine the length of the PCL and its bands, to evaluate the length variation during movement, and to determine the optimal location for the insertion of an intraarticular graft, that would lead to the least stretch during flexion. It was found that the mean length of the PCL was 30.2 mm, with the posterior band being 30% longer than the anterior band. During flexion the posterior band increases its length by 10% at 50 degrees flexion, and by 20% at 75 degrees flexion. The anterior band stretches more, to reach 40% elongation at 75 degrees flexion. The best position for insertion of a graft seems to be in the posterolateral portion of the anatomic tibial insertion, and posterior to the anatomic femoral insertion. This method confirms the data in the literature, states precisely the length of the different bands of the PCL, and specifies the points of insertion for a graft, which lead to the least variation in length during flexion.

Biometry↗
PubMed1998

[Failure of the polyethylene cups directly implanted into bone. A study of 32 Freeman cups after 9 years of followup (6-12 years)].

PURPOSE OF THE STUDY: A clinical and radiological assessment was performed on 32 Freeman polyethylene uncemented acetabular cups, at an average of 9 years follow up. This study was dedicated to analyze polyethylene bone direct fixation. MATERIAL: Between 1984 and 1988, 30 patients were operated for 32 total hip prostheses. Mean age of the population at the time of surgery was 66 years. In all cases the prosthesis was a cemented Müller femoral stem with a Freeman uncemented cup. The acetabular component was made with polyethylene with three pegs fitted with an offset hemispheric cup. METHOD: All patients were reviewed at 1, 3, 5 years and maximal follow-up. Their functional evaluation was performed using Merle d'Aubigné's hip rating scale: pain score, motion score and walking score. Radiological assessment was performed to identify acetabular cup migration, bone lysis, and radio lucency. Revision for acetabular cup loosening was compiled. RESULTS: Five patients died, 27 THA were evaluated at maximum follow-up. Seven revisions were performed after the fifth years. Merle d'Aubigné's score was 14 at the time of revision. X-rays evidenced more than 5 mm migration of the cup, with massive bone lysis. Merle d'Aubigné's score was 16 for the 20 remaining THA. Radiologically, 10 cups showed migration less than 3 mm, five of which with lysis. Among the 10 cups without migration, 5 showed sclerosis near the acetabulum. The study evidenced that cases of migration exceeding 5 mm induced a revision during the next 3 years. DISCUSSION: Our study confirms failure of bone polyethylene direct fixation, with 25 per cent of revision after a five years period. This seems to be the result of micro movement, wear and bone lysis. A five years follow up is not sufficient to evaluate a component, since all revisions were performed after five years. For many authors, radiological evaluation of acetabular component migration is an important criterion for uncemented prosthesis. The EBRA computerized method is an accurate method for determining early migration, and can be used for pro and retrospective studies. CONCLUSION: Our study confirms a high rate of failures of the Freeman uncemented cup at an average of nine-year period, as previously reported in literature.

Acetabulum↗
PubMed1997

[Radiological evaluation of integration of bone grafts and bone substitutes after implantation to replace acetabular substance losses in reoperation of total hip prosthesis].

Plain radiograms are insufficient to evaluate the integrity of a graft used to replace acetabular tissue loss in reoperations for total hip replacement. The aim of this work was to compare radiographic, computed tomographic and magnetic resonance imaging findings. Two groups of patients including 12 hip joints in each were evaluated 5 years after undergoing reoperation for annular support. Allografts (5 cases) or xenografts (7 cases) were used in one group. Plain radiograms. CT-scan and MRI were performed in each patient. The graft-receiver bone borders were visible on the CT-scans but were not distinguishable on the radiograms. Bone and graft density and structure in contact with the implant could be determined on the CT-scan. MRI was difficult to interpret in most cases due to implant-induced artefacts and is not recommended in this type of reconstruction.

Adult↗
PubMed1996

[Scapho-capitate fracture. Apropos of a case, review of the literature].

Scapho-capitate fracture is a rare lesion. Its mechanism is controversial. Forced extension seems to be the most frequent etiology, as this movement of the wrist induces scaphoid fracture by compression. Hyperextension of the wrist, as a result of the scaphoid lesion, allows contact between the posterior margin of the radius and the neck of the capitatum, inducing capitatum fracture. Continuation of the movement allows a two-stroke rotation of the capitate proximal pole. Analysis of a personal case and review of the literature demonstrated: the frequency of extension movement for etiology, delayed diagnosis, and the need for surgery. Surgery should be performed early with capitate reduction and osteosynthesis in case of instability, scaphoid reduction and minimal osteosynthesis a graft may be necessary. Immobilisation of the carpus and the thumb is essential until bone consolidation. Early surgery should avoid complications such as necrosis or pseudarthrosis.

Adult↗
PubMed1996

Acetabular reconstruction in total hip revision using a bone graft substitute. Early clinical and radiographic results.

Thirty revisions were performed on loose total hip replacements with a specific acetabular reconstruction technique combining the use of a bovine bone substitute and a support ring. One patient died of a cause unrelated to the procedure. No migration of the acetabular implant or bone lysis of the heterograft was seen in 27 cases after 3 years. Radiologically, the heterograft gradually condensed, and its appearance matched that observed with an allograft. The 2 failures with implant migration and heterograft lysis were interpreted as technical errors related to the use of the Müller ring. In both cases the Müller ring was supported by the cancellous heterograft and not by the host bone.

Acetabulum↗
PubMed1992

[Value of puncture-arthrography in the diagnosis of infection of total hip arthroplasty].

Arthrography with hip aspiration was performed in 143 patients with hip arthroplasties to determine its effectiveness as a technique for diagnosing infection. Thirty-three cases of infection were found. On 26 occasions the germ responsible was isolated in the joint fluid. In six other cases infection was revealed from cytologic or arthrographic findings, or from both. Only once was a diagnosis of infection not arrived at. In this series of patients, except in cases of evolutive inflammatory rheumatism, cytologic examination of the joint fluid was a discriminative factor in diagnosis. Hip aspiration arthrography had a sensitivity of 79 per cent for the diagnosis of infection in arthroplasty with isolation of the germ and a specificity of 100 per cent. The sensitivity of the diagnosis rose to 91% when any one of the following features was observed: leucocytosis of the joint fluid higher than 10,000 elements/mm3; presence of a fistula or of fistulization on arthrography; isolation of the germ in the joint fluid or the rinsing liquid.

Arthrography↗
PubMed1988

[Our experience with ofloxacin in the treatment of osteoarticular infections].

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.

Adult↗
PubMed1984

[Automatic retroversion of the femur neck during fasciculated nailing of pertrochanteric fractures by the Ender method].

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.

Aged↗
PubMed1984

[Patellar complications of ICLH knee prosthesis].

Three types of patellar complication following total knee replacement with a Freeman-I.C.L.H. prosthesis have been studied. They are: 1) Pain despite a satisfactory position of the patella. 2) Patella fractures and 3) Lateral displacement. Pain in spite of a satisfactory position of the patella occurred in 15 p. 100 of cases. The incidence of this complication was considerably diminished by the use of a patellar implant. The use of a patellar implant did not result in any specific morbidity. Five fractures of the patella were seen, three of them without displacement. Lateral displacement of the patella were seen in 5 p. 100 of cases resulting in instability of the knee and a higher risk of loosening of the tibial component. The authors propose a new type of patellar implant stabilized by a rail.

Female↗
PubMed1983

Isolated traumatic dorsal dislocation of the distal radio-ulnar joint. Report of seven cases.

The authors report seven cases of isolated dorsal dislocations of the distal radio-ulnar joint. Four were recent dislocations and three were old, chronic dislocations. Acute dislocations were treated surgically. An anatomic study on human cadavers enabled us to define the injuries responsible for radio-ulnar dislocations. An electromyographic study of the extensor carpi ulnaris confirmed its role as a dynamic stabilizer of the ulnar head. Two of the three old dislocations were revised after an attempt at ligamentous reconstruction. These patients benefitted from a resection of the ulnar head. The third patient one underwent a Sauve-Kapandji procedure. Cadaver studies underline the fact that ligamentous reconstruction procedures are actually tenodeses.

Acute Disease↗
PubMed1983

Why not resurface the patella?

The results of resurfacing or not resurfacing the articular cartilage of the patella were reviewed in 71 knees--47 with rheumatoid arthritis and 24 with osteoarthritis--which had been replaced with the ICLH prosthesis. Two rheumatoid and osteoporotic patellae developed transverse fractures with separation and were excluded from the review. The results showed that resurfacing the patella greatly reduced peripatellar pain with no counter-balancing disadvantage.

Aged↗