Biomedical subjects

L Munuera

Publications and source records attributed to L Munuera.

At least 37 records · Page 2Linked to original sources

PubMed1997

Femoral osteolysis after low-friction arthroplasty. A planimetric study and volumetric estimate.

Sixty-three cases of femoral osteolytic cavities were analyzed in a consecutive series of 680 low-friction arthroplasties of the hip performed in 598 patients between 1971 and 1979. Follow-up evaluation averaged 15 years 9 months (range, 2-22 years). The total cumulative probability of osteolysis developing after 20 years was 11% according to survivorship analysis. The mean time of appearance of the osteolytic lesion was 9 years 3 months after operation. Most of the cavities were seen in Gruen zones 3, 5, and 7 in decreasing order. Osteolytic cavities were classified as follows: group 1, cavities in cases with radiographic definite stem loosening (20 cases); group 2, cavities in cases with an acetabular wear equal to or greater than 2 mm (22 cases); and group 3, cavities in cases combining both of the above-mentioned findings (21 cases). Cementing defects such as voids and thin mantles were less frequent in group 2 than in groups 1 and 3 (P < .005). Poor clinical results were more frequent in groups 1 and 3 (P < .05), in all instances). Focal cavities were more frequent in group 2, and multifocal and diffuse cavities were more frequent in groups 1 and 3 (P < .05). The average planimetric area on radiographic diagnosis was 0.81 cm2, and the average approximate volume was 1.86 cm3, with significant differences among the three groups of cavities. Progression of the cavity area and volume was linear over time (P < .001) and more aggressive in groups 1 and 3 than in group 2 (P < .05). Thus, loosening of the stem was a more deciding factor than acetabular wear in the progression of cavities.

Adult↗

PubMed1997

Progression of radiolucent lines adjacent to the acetabular component and factors influencing migration after Charnley low-friction total hip arthroplasty.

We analyzed the progression of radiolucent lines around the acetabular cup after 452 Charnley low-friction arthroplasties that had been performed in 392 patients between 1971 and 1976. The average duration of follow-up was twenty years (range, eleven to twenty-five years) for the 442 hips (382 patients) that had the original component in place at ten years. The demarcation of the bone-cement interface was classified according to the system of Hodgkinson et al. We sought to determine if there was a relationship between the progression of the radiolucent line and the age, gender, and weight of the patient; the level of activity; the preoperative diagnosis; or the amount of wear of the acetabular cup. The demarcation increased over time in 138 (31 per cent) of the 452 hips. Radiographs made at the time of the latest follow-up showed migration of eleven (5 per cent) of the 233 acetabular cups with no demarcation on the initial postoperative radiograph, eighteen (11 per cent) of the 167 cups with type-1 demarcation, twelve (35 per cent) of the thirty-four cups with type-2 demarcation, and thirteen of the eighteen cups with type-3 demarcation. Preoperative acetabular protrusion, inflammatory arthritis, and severe acetabular dysplasia as well as a previous operation were associated with the extent of the radiolucent line on the most recent radiograph (p < or = 0.05 for all). A high level of activity and more than two millimeters of wear of the acetabular cup also were related to the progression of the radiolucent line (p = 0.0004 and p < 0.0001, respectively). Kaplan-Meier survivorship analysis demonstrated that the greater the demarcation on the initial postoperative radiograph, the greater the risk of migration (p < 0.0001, Mantel-Cox test). Our data suggest that, after a Charnley low-friction arthroplasty, any cemented cup, even one with the least amount of demarcation (types 0 and 1), can migrate. As the type of the initial postoperative demarcation increases, so does the risk of migration of the cup, particularly when there is loss of the acetabular bone stock.

Acetabulum↗

PubMed1997

Neural and muscular electric activity in the cat's knee. Changes when the anterior cruciate ligament is transected.

We studied the response of the normal and unstable knee to passive motion and anterior tibial displacement in the cat. 6 cats were anesthetized and the deep level of anesthesia was controlled by electroencephalograms. We recorded electric activity in the articular nerves (posterior PAN and medial MAN) and periarticular muscles (quadriceps and hamstring), while performing passive flexion, extension, internal and external rotation. We then produced anterior displacement of the tibia at 30 degrees and 90 degrees of flexion, as in the Lachman and the anterior drawer maneuvers. The anterior cruciate ligament was surgically sectioned and the same series of passive displacements was performed. We observed statistically significant increased activity in the MAN, the PAN and the quadriceps muscle during knee flexion, in the MAN during extension, and in the PAN and hamstring during external rotation with the knee 90 degrees flexed. Anterior cruciate transection caused anterior displacement of the tibia during stress. This produced a significant increase in the MAN activity and a significant decrease in the hamstring electric activity at 30 degrees and 90 degrees of flexion, as in Lachman and anterior drawer maneuvers. We conclude that electric activity in the articular nerves and periarticular muscles, in response to passive motion and anterior tibial displacement, is altered in the cat's knee after anterior cruciate transection. This suggests that various patterns of periarticular muscle reaction in the anterior cruciate-deficient knee may be related to the unconscious perception of abnormal motion.

Animals↗

PubMed1996

[Vitamin D levels in patients with hip fracture in Madrid].

BACKGROUND: Vitamin D appears to be implicated in the loss of bone mass and its most severe complication is the hip fracture. A change is produced in the metabolism of vitamin D in elderly people although its study has received little attention in many countries. METHODS: With the aim of evaluating vitamin D and its metabolites in the elderly people with hip fracture in our geographic environment (Madrid, Spain), 58 patients with hip fracture over the age of 70, and 39 subjects without a fracture or the similar age were studied. Both groups were evaluated during the season of minimum solar irradiation. The plasma concentrations of intact PTH and the serum concentrations of calcidiol and calcitriol were studied in all the patients. RESULTS: The patients with hip fracture presented significantly lower concentrations of calcidiol (11.7 +/- 6.4 vs. 18.4 +/- 12.7 nmol/l) and calcitriol (60.1 +/- 24.7 vs. 76.1 +/- 25.0 pmol/l) than in elderly persons without fracture, with similar PTH values being observed in both groups (4.8 +/- 1.9 vs. 5.1 +/- 2.3 pmol/l). CONCLUSIONS: Although Madrid, Spain is considered to be a geographical area of high solar irradiation, the elderly population studied presented a vitamin D deficiency which was found to be greater in those with hip fracture.

Age Factors↗

PubMed1996

Influence of bacterial strains on bone infection.

Experiments were performed on 120 rabbits to compare the probability of infection after bone surgery without an implant, with polymethylmethacrylate, and with autografts. Staphylococcus aureus phage type 94/96, isolated from a human osteomyelitis, was instilled into the intramedullar cavity after reaming of the femoral canal and before insertion of the implant. The different 50% infective doses were determined for each of the groups for comparative purposes. The bacterial concentrations required to produce infection in femora without an implant were two times less than those necessary in femora implanted with polymethylmethacrylate. The bone graft required bacterial concentrations nine times less than those necessary to infect femora containing polymethylmethacrylate and four times less than those required to infect femora without an implant. The results presented here confirm that the susceptibility to infection in orthopaedic surgery is not only material dependent but also bacteria dependent.

Animals↗

PubMed1996

The influence of the chemical composition and surface of the implant on infection.

The influence of the localization and size of orthopaedic implants on infection has been analyzed extensively, but the influence of implant shape and chemical composition has rarely been studied, and the influence of the surface has only been described in one single report. Several experimental studies have tried to compare the incidence of infection for different materials. PMMA usually appears as the implant material most prone to causing infection, while titanium (Ti) and cobalt-chromium (CoCr) are the materials most resistant to infection. On the polished surface of cylinders implanted in rabbit femora, it took 40 times more inoculum to produce a clinical infection than it took for porous CoCr implants. The polished surface implants required 2.5 times more inoculum than porous Ti to produce infection.

Animals↗

PubMed1996

Mittelmeier ceramic-ceramic prosthesis after 10 years.

The clinical status of 83 Mittelmeier ceramic-ceramic (Mark II) cementless total hip prostheses (Autophor, Osteo AG, Selzach, Switzerland) implanted between 1978 and 1984 was analyzed. Retrieved tissue from the revised hips was studied histologically. The mean patient age was 47.5 years (range, 19-71 years). One or both components of 12 hips were revised (16% at 16 years in the survival study). Eleven acetabular components and seven stems were revised, with three of the sockets fractured. The mean follow-up period for the patients with unrevised hips was 12.3 years. Osseointegration was uncommon in both the cup and stem. Radiographic cup loosening was observed in 53% of hips at 16 years in the survival study, with most having a complete radiolucent line of 2 mm around the cup. Radiographic stem loosening appeared in 15% of hips at 16 years. Fibrous stable fixation was present in 64% of stems. Significant radiographic acetabular wear was not observed in any hip. The Mittelmeier Mark II prosthesis had worse long-term results than reported with cemented or other uncemented prostheses. Although there was no significant acetabular wear, intracellular ceramic wear debris was seen in the retrieved tissues.

Adult↗

PubMed1996

Segmental sensory innervation of the anterior cruciate ligament and the patellar tendon of the cat's knee.

We performed a study in cats to describe and quantify the segmental sensory innervation of the anterior cruciate ligament of the knee. We also studied the patellar tendon to show that transport occurs from an extraarticular, dense connective tissue structure and to obtain comparable quantitative information. We injected a tracer (horseradish peroxidase HRP, coupled to wheat germ agglutinin WGA) in the anterior cruciate ligament and observed the reaction product in the articular nerves of the injected knee and in the cell bodies of ipsilateral dorsal root ganglia. In these experiments, we found an average of 26 (13-52) labeled neurons, mostly large, after injecting the anterior cruciate. More than half of the labeled neurons were found in the dorsal root ganglion of L7 (last lumbar segment in the cat). We counted an average of 204 (17-426) labeled neurons, mostly small, after injecting the patellar tendon. More than half of these labeled neurons were found in the L5 spinal ganglion. No product was observed in contralateral spinal ganglia. Surgical ablation of the medial and lateral articular nerves (MAN and LAN) before injecting HRP-WGA in the anterior cruciate ligament, showed that the remaining afferents in the posterior articular nerve (PAN) projected mainly to L7. After excision of PAN, the projection was maintained through MAN and LAN, mostly to L5. Our quantitative data show that the anterior cruciate ligament is poorly innervated, if compared to the patellar tendon. The anterior cruciate segmental sensory innervation is directed to L7 (corresponding to the main ventral root forming the sciatic nerve in the cat), but also to L5 and L6 (main femoral nerve ventral roots). These segmental data indicate that anterior cruciate innervation influences muscle tone regulation, not only of the hamstrings (neuromuscular system of the sciatic nerve), but also of the quadriceps muscle (neuromuscular system of the femoral nerve).

Animals↗

PubMed1995

The fixation of porous-coated femoral stems. A radiographic study of 113 cases with a 4 to 8 year follow up.

Changes occurring in the fixation of 113 porous-coated PCA uncemented femoral stems were studied in 90 patients who were operated on between 1984 and 1988. The average follow up was 5 years. Fixation was classified in radiographs as osteointegration, stable fibrous fixation or unstable. Four femoral components were revised. Metaphyseal osteoporosis was associated with those with a stem diameter greater than 13 mm. After 2 years, osteointegration was present in 73% and instability in 24% which was not related to the position of the stem. At the end of the follow up period, 20% of the stems showing osteointegration had changed and become unstable.

Adult↗

PubMed1995

Long-term results of aseptic cemented Charnley revisions.

One hundred eighty low-friction arthroplasties of the hip in 164 patients in first-time revision surgery were operated between 1973 and 1985. This series used only cement fixation, and aseptic loosening and femoral stem fractures were the only indications for revision. The average follow-up period was 11.5 years. Intra-operative and postoperative complications were frequent: femoral shaft fracture (13 cases), femoral shaft perforation (12 cases), deep infection (14 cases), and dislocation (15 cases). Twenty-eight hips were rerevised or removed (resulting in a total cumulative probability of rerevision of 20% after 16 years, according to survivorship analysis). Nineteen cups were rerevised (13% after 16 years, according to survivorship analysis), and 24 femoral stems were rerevised (16% after 16 years, according to survivorship analysis). Radiographic cup and femoral loosening appeared in 29 and 36 cases, respectively (24 and 22% after 16 years, respectively, according to survivorship analysis). Good results were observed when there was a healthy and intact bone bed, whereas poor results were related to inadequate bone stock in the acetabulum and femur. Radiolucent lines were frequent in both components; radiolucent lines less than 2 mm wide were frequent in acetabular zone 1. Pistoning of the prosthesis and the cement within the bone and calcar pivot was the most frequent type of stem loosening.

Bone Cements↗

PubMed1994

Relations between calcidiol serum levels and bone mineral density in postmenopausal women with low bone density.

The relationship between vitamin D and bone density was studied in 150 selected, mature (45-74), postmenopausal women with a lumbar spine Z score below 0. Vitamin D status was evaluated using calcidiol serum levels. Serum calcitriol and parathyroid hormone (PTH) values were also evaluated in some subjects. Bone mass was evaluated by ascertaining bone density and Z and T scores in the lumbar spine and femur region. The reference group consisted of 25 premenopausal women. The postmenopausal group was divided into subgroups according to age, i.e., under or over 60 years old. Additionally, the whole group was also subdivided according to their lumbar spine Z scores into group I (Z > -1), group II (Z < -1; > -2), and group III (Z < -2). Group III of postmenopausal women had higher PTH and lower calcitriol levels than premenopausal women. Calcidiol serum levels were lower in postmenopausal women groups II or III than in the group I and premenopausal women. Calcidiol serum levels and the bone mass values for the lumbar spine were correlated positively in all the postmenopausal women; in the women over 60 years of age, calcidiol levels also correlated with the bone mass values expressed as the bone density in three femur regions: femoral neck, trocanter, and Ward's triangle. In conclusion, mature post-menopausal woman showed high PTH levels and low calcidiol and calcitriol values. Calcidiol status is significantly related to bone mineral density in the lumbar spine and in women over 60 years, calcidiol levels also correlated with bone density in the femur regions.

Adult↗

PubMed1994

Fixation of cementless acetabular cups. A radiographic 4-8-year study of 102 porous-coated components.

We studied fixation changes over time in 113 porous-coated Howmedica (PCA) cementless acetabular cups inserted in 90 patients 1984-1988. The mean follow-up was 5 years. Radiographic fixation was classified as stable, fibrous-stable, or unstable. 9 cups, 3 in neutral position and 6 vertical, were revised. At follow-up, 40/75 neutral cups were stable versus 7/27 vertical cups. Most stable cups and two thirds of the unstable cups were clinically good. After the first 2 years, 28/75 neutral cups and 10/27 vertical cups changed their fixation; 12 had improved fixation and 26 had a worse one.

Acetabulum↗

PubMed1994

Influence of metal implants on infection. An experimental study in rabbits.

We implanted cylinders of cobalt-chrome or titanium, with smooth or porous surfaces, into rabbit bones which had been inoculated with suspensions of Staphylococcus aureus in various doses. The bacterial concentration required to produce infection of porous-coated titanium implants was 2.5 times smaller than that necessary to infect implants with polished surfaces. Porous-coated cobalt-chromium implants required bacterial concentrations that were 40 times smaller than those needed to infect implants with polished surfaces, and 15 times smaller than those required to infect porous-coated titanium implants. The other advantages and disadvantages of the various implants, such as improved osseointegration, larger ion-release surfaces, surface wear and relative stiffness, must be weighed against the higher infection rates in the porous-coated implants, and particularly in the cobalt-chromium implants.

Animals↗

PubMed1993

Adolescent idiopathic scoliosis and joint laxity. A study with somatosensory evoked potentials.

To assess the existence of disturbances in proprioception in adolescent idiopathic scoliosis and an hypothetical relationship with generalized joint laxity, a blind comparative study of short-latency somatosensory evoked potentials by posterior tibial nerve stimulation was designed. One hundred twenty-one subjects were included: fifty-two were diagnosed as having adolescent idiopathic scoliosis, thirty-two met criteria for generalized joint laxity, twenty-one had curvatures with Cobb angles less than 10, and twenty-eight were matched control subjects; twelve subjects were initially seen with both adolescent idiopathic scoliosis and generalized joint laxity. We failed to find alterations in somatosensory evoked potentials in patients with adolescent idiopathic scoliosis that could suggest proprioceptive disturbances as a causative factor; however, in a subgroup of thoracolumbar curvatures we were able to demonstrate a functional alteration in somatosensory evoked potentials that could represent a neurologic basis for some curves considered as idiopathic thus far; generalized joint laxity seems to be implicated in this situation.

Adolescent↗

PubMed1993

Low-friction arthroplasty in severe acetabular dysplasia.

Eighty consecutive low-friction arthroplasties in 64 patients with secondary arthritis due to severe acetabular dysplasia (Crowe grades III and IV) are analyzed. Two groups of patients were considered. In group 1 over 20% of the cup was not covered by the acetabulum and was reconstructed with a femoral head graft (32 cases; in group 2) a femoral head graft was not used because the cup was adequately covered (48 cases). The mean follow-up period was 9.4 years (range, 3-17 years) for group 1 and 8.8 years (range, 3-18 years) for group 2. Early complications were frequent (19%). To study long-term results only 78 hips were assessed since two patients were excluded due to deep infection. In these 78 hips, group 1 patients showed "better" results after 16 years (69.6% good results) than group 2 (nongraft procedures) (52.2%), but these differences were not significant (P > or = .05). Early cup loosening was more frequent in group 2 than in group 1, and good coverage was obtained in 91% of the group 1 cups and in 71% of the group 2 cups (P > or = .05). Acetabular cup loosening was not correlated with acetabular cup position. Bone-grafts appeared consolidated in all cases, but resorption areas were frequently observed. Radiographic stem aseptic loosening appeared in 10 cases, cortical hypertrophy in 7 cases, and endosteal osteolysis in 3 cases. Although limb discrepancy was frequent in both groups (75%), the average discrepancy was 1.7 cm.

Adult↗

PubMed1992

Intertrochanteric osteotomy for the treatment of chronic slipped capital femoral epiphysis.

Thirty six patients with a chronic slip of the capital femoral epiphysis and a femoral headneck angle of more than 30 degrees, as measured in a lateral radiograph, were treated by intertrochanteric osteotomy. The patients had an abnormal gait, an average age of 14.1 years and symptoms for an average of 14.5 months. The postoperative complications included two patients with avascular necrosis of the femoral head, four with coxa vara and two with loss of position requiring further operation. At an average of 7.5 years after operation 14 were good, 18 fair, and 4 poor on clinical assessment, with 13 good, 19 fair and 4 poor when judged by radiographs. Patients with complications had only fair or poor results. A postoperative head-neck angle of less than 10 degrees indicated a good result.

Adolescent↗

PubMed1992

Femoral shaft fractures after cemented total hip arthroplasty.

Thirty-seven femoral shaft fractures occurred in 2360 cemented hip arthroplasties carried out between 1971 and 1989 at varying intervals after operation (average 3.7 years). Three types of fracture were recognised and treatment depended on the type, as did the prognosis. Good results were obtained in 70% of the cases.

Adult↗

PubMed1992

Dislocation in low-friction arthroplasty.

In a series of 2,050 low-friction arthroplasties, 61 cases (2.97%) of dislocation were analyzed. The mechanism of production was malposition of the components (group 1, 33%), deficiency of the abductor mechanism (group 2, 34%), or the association of both (group 3, 26%). Failure to find a cause was even more rare (group 4, 7%). The best treatment is prevention by careful surgical technique, since good results with different procedures have only been attained in 51% of dislocated hips.

Adult↗