Navigated versus conventional total knee arthroplasty: A prospective study at three years follow-up. / Artroplastia total de rodilla navegada versus convencional; estudio prospectivo a 3 años de seguimiento.

OBJECTIVE: Computer-assisted surgery application in total knee arthroplasty (TKA) has shown more accurate implant alignment compared with conventional instrumentation and is associated with more homogeneous alignment results. Although longer implant survival and superior clinical outcomes should be expected from navigated TKA, currently available evidence does not support this hypothesis. The aim of this study was to compare navigated TKA with conventional TKA regarding clinical and radiological outcomes after a 3-year follow-up under the hypothesis that navigated TKA would provide better outcomes than conventional TKA. MATERIAL AND METHOD: In a prospective multicentre study, 119 patients underwent navigated TKA and 80 patients received conventional instrumentation. Patients were evaluated at the baseline and at postoperative months 3, 12, 24, and 36. Analysis included the American Knee Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form-12 (SF12) Health Survey, and radiographic assessment. RESULTS: All clinical scores improved significantly for all patients during the follow-up but were significantly better in the navigation group. The percentage of patients showing a mechanical axis between 3° of varus and 3° of valgus was significantly higher in the ATR group (93%) than in the conventional TKA group (71%) (P<.01). CONCLUSIONS: The use of computer-assisted surgery in TKA provides more accurate mechanical alignment and superior short-term functional outcomes compared to conventional TKA.

Frontal alignment in total knee arthroplasty. Comparative study between radiographic measurement and surgical navigation. / Alineación frontal en la artroplastia total de rodilla. Estudio comparativo entre medición radiográfica y con navegación quirúrgica.

OBJECTIVE: To establish the concordance between angulation of the femoro-tibial mechanical axis measured with x-rays and surgical navigation in both the pre and postoperative period after a total knee arthroplasty (TKA) was implanted. MATERIAL AND METHOD: Pre and postoperative measurements were analyzed in 88 TKA of the same model and all performed with the same surgical navigation system. The mechanical frontal angle (MFA) and femoro-tibial anatomic angle were measured before and after the TKA. The angulation was digitally measured with a teleradiography. In the navigation, the femoro-tibial angle at rest, forced varus and valgus were registered and the average of these three measurements was calculated. RESULTS: The mean preoperative MFA measured on the radiograph was 4.55°. The mean of the same angle measured on the postoperative radiograph was 1.72°, (p=0.05). The mean of the MFA measured with navigation before TKA was 3.12° and after the implant with navigation was 0.53 (P=.013). The concordance coefficient between the MFA in teleradiography and in navigation was 0.869 (P<.001) preoperatively and 0.709 postoperatively (P=.017). CONCLUSIONS: We found a strong concordance between radiographic and surgical navigation measurements of the MFA. This may imply that teleradiography is not necessary when using surgical navigation in TKA.

Normal frequencies of the C677T genotypes on the methylenetetrahydrofolate reductase (MTHFR) gene among lymphoproliferative disorders but not in multiple myeloma.

The folate availability seems to be critical for the DNA integrity since it is required for the transfer of methyl groups in the biosynthesis of thymidilate. Although the excessive incorporation of uracils to the DNA can be efficiently removed, this mechanism of reparation produces many double-strand breaks from two opposing nicks. Several chromosomal abnormalities (mainly translocations and deletions perhaps not well understood) are involved in the origin of lymphoproliferative disorders. The TT homozygosity at nucleotide 677 in the gene of methylene tetrahydrofolatereductase (MTHFR), a key enzyme in folate metabolism, was recently linked to a significant protection against colon carcinoma and acute lymphoblastic leukaemia in adults. We analysed the genotype frequencies of C677T-MTHFR in a group of 143 patients with lymphoproliferative disorders (REAL classification) and 200 controls. Overally, the frequencies of the polymorphic allele were similar (35.3% and 32.0% respectively)(P=0.6). We did not find differences between patients and controls except for myeloma/plasmacytoma group (n=26) which showed a CC genotype less than expected (19% vs 46%) (p=0.01) with a frequency ratio of 0.28 (0.10-0.77). Even among the IgG myeloma cases only one patient showed a common genotype (CC) (1/15, 7%) (P=0.003). If these preliminary data are validated with prospective studies, the 677C allele of MTHFR gene could be confirmed as an effective multiple myeloma protective factor (specially for the IgG cases).

Risk of venous thromboembolism associated with the insertion/deletion polymorphism in the angiotensin-converting enzyme gene.

The circulating levels of angiotensin I-converting enzyme (ACE) are linked with a 287-base pair insertion/deletion (I/D) polymorphism at intron 16 of the ACE gene. Thus, the homozygous deletion (D/D genotype) could cause chronic vasoconstriction, arterial hypertension and, possibly, coronary artery disease. Also, the increase in plasminogen activator inhibitor-1 level and impaired fibrinolysis were related with the D/D genotype. The D allele has been recently associated with venous thrombosis among African-American men as well as among patients that underwent elective total hip replacement. We assess the risk of venous thromboembolism (VTE) linked with each genotype of the I/D ACE gene polymorphism in a Caucasian population by means of a case-control study. We genotyped the ACE gene in a series of 148 patients aged 45.0 +/- 16.0 years (range, 11-80 years), objectively diagnosed in our centre of deep-vein thrombosis or pulmonary embolism, and in 240 thrombosis-free subjects (25-75 years) from the same geographic area. The observed difference in D allele frequencies between patients (0.56) and controls (0.62) was nonsignificant overall; however, statistical significance (P = 0.05) was found by considering the recessive hypothesis (D/D versus I/ D + I/I) [odds ratio (OR) = 0.64, 95% confidence interval (CI95) = 0.42-0.99]. The OR was 0.88 (CI95 = 0.51-1.53; P = 0.65) for the dominant hypothesis (D/D + I/D versus I/I genotypes). The relative risk for the D allele was close to 1 for the dominant hypothesis, both considering gender and recurrent tendency; however, it was protective in men regarding the recessive hypothesis (OR = 0.53, CI95 = 0.29-0.97, P = 0.04). The I/D ACE allele distribution was similar among the 46 thrombophilic patients (antithrombin, protein C or protein S deficiencies, factor V R506Q, factor II G20210A or lupus anticoagulant). In conclusion, among (Spanish) Caucasians, this study does not support the hypothesis that the deletion allele (D) of the ACE gene could be a significant risk factor for VTE, being protective in men.

[Lowering high levels of fasting total homocysteine with folic acid and vitamins B in patients with venous thromboembolism: relationship between response and the C677T methylenetetrahydrofolate reductase (MTHRF) genotype]. / Reducción de concentraciones elevadas de homocisteína con ácido fólico y vitaminas B en pacientes con tromboembolia venosa: relación entre respuesta y genotipo C677T de la metilén tetrahidrofólico reductasa (MTHFR).

BACKGROUND: High levels of plasma total homocysteine (tHcy) are involved in arterial or venous occlusive diseases. It essentially depends on the nutritional status of folic acid (FA) and vitamins B12 or B6, but also on the methylenetetrahydrofolate reductase (MTHFR) enzymatic activity. We aim to evaluate the response of the hyperhomocysteinemia (HHcy) to a standard schedule of vitamin supplementation, according with the MTHFR genotype. PATIENTS AND METHODS: 227 patients, diagnosed with venous thromboembolism (VTE) were analysed for tHcy (in fasting conditions), and for the MTHFR-C677T gene polymorphism. When the tHcy exceeded the cut-off point (men = 16, women = 15 mumol/l), the patients were supplemented with a dose equivalent to 1 mg FA, 0.2 mg B12 and 100 mg of B6, daily by 6 weeks. Afterwards they were reanalysed and the reduction was stratified by MTHFR genotype, looking for any difference in the response. RESULTS: The mean fasting tHcy was 12.3 mumol/l (SD = 8). The 51 hyperhomocysteinemic patients (22%) were older (65.1 y) than the normal ones (55.0 y) (p = 0.0001). The treatment was carried out properly in 46 patients (90%). The pre-treatment mean Hcy was 23.2 (SD = 10.5) mumol/l, and it was reduced to 13.0 (SD = 5.9) (p = 0.0001) (mean reduction = 42.1%). By genotype, the C/C reduced from 21.0 to 13.2 mumol/l (37%) (n = 18), the C/T from 25.0 to 12.6 mumol/l (46%) (n = 24), and the abnormal homozygotes T/T from 22.7 to 14.5 mumol/l (39%) (n = 4), although no statistical significant differences were found. In 80% of cases (37/46), tHcy values normalised. A negative correlation (r = -0.471) (p = 0.005) was observed between age and response. CONCLUSIONS: The FA/B6/B12 based therapy reduces in a simple, quick and effective way (> 40% in 6 weeks) the pathologic tHcy levels on a VTE population and this is not influenced by the MTHFR genotype. As HHcy seems related with recurrences of venous thrombosis, we could speculate if it would be useful to analyse routinely the tHcy, attempting reduction in selected cases.

[Detection of metal ions in hair after metal-metal hip arthroplasty]. / Detección de iones metálicos en cabello tras artroplastia de cadera metal-metal.

OBJECTIVE: There is an increase in the levels of metals in the serum and urine after the implantation of some models of metal-metal hip prosthesis. It has recently been demonstrated that there is an association between these levels and the levels found in hair. The aim of this study is to determine the presence of metals in hair, and to find out whether these change over time or with the removal of the implant. MATERIAL AND METHOD: The levels of chromium, cobalt and molybdenum were determined in the hair of 45 patients at 3, 4, 5, and 6 years after a hip surface replacement. The mean age was 57.5 years, and two were female. Further surgery was required to remove the replacement and implant a new model with metal-polyethylene friction in 11 patients, 5 of them due to metallosis and a periarticular cyst. RESULTS: The mean levels of metals in hair were chromium 163.27 ppm, cobalt 61.98 ppm, and molybdenum 31.36 ppm, much higher than the levels found in the general population. A decrease in the levels of chromium (43.8%), molybdenum (51.1%), and cobalt (91.1%) was observed at one year in the patients who had further surgery to remove the prosthesis. CONCLUSIONS: High concentrations of metals in the hair are observed in hip replacements with metal-metal friction, which decrease when that implant is removed. The determination of metal ions in hair could be a good marker of the metal poisoning that occurs in these arthroplasty models.

[Spinal cord infarction and recurrent venous thrombosis in association with estrogens and the 20210A allele of the prothrombin gene]. / Mielopatía aguda isquémica y trombosis venosa recurrente asociada a estrógenos y alelo 20210A del gen de la protrombina.

The acute spinal cord infarction is a rare cause of acute-onset paraplegia. Furthermore, it is specially uncommon that the infarction occurs in patients with apparent low predisposition to vascular disease. The 20210A allele of the prothrombin gene (causing a threefold-increased risk in venous thromboembolism) was recently associated with unexplained spinal cord infarction in young women under treatment with estrogens (contraceptive pill). We report a case of anterior spinal artery syndrome resulting from an ischaemic infarction at the anterior aspect of the spinal cord in a healthy 50-year-old woman, carrying this mutation, being the first published case under treatment with transdermal estradiol. She referred the typical sudden-onset back pain associated to clinical anterior spinal artery syndrome with sphincter dysfunction and nontraumatic paraplegia. A possible multiple sclerosis was ruled out and the steroids or immunoglobulin therapy induced no clinical improvement. Cerebrospinal fluid and other investigations were all negative. Sequential MRI scans revealed development of spinal cord infarction from T10 to T11, with increased signal in T2-weighted image (T2). Because she referred a previous thrombophlebitis and suffered a deep-vein thrombosis one month after paraplegia, a complete coagulation study was performed. Antithrombin, proteins C and S, homocysteine, factor V Leiden, lupus anticoagulant and anticardiolipin antibodies were all normal or negatives. In opposite, the 20210A variation was positive (heterozygous) and the factor VIIIc level was very high (280 U/dl eight months later). We argue the relative importance of both findings. The patient had no a substantial recovery over a period of 20 months.Certainly, the prothrombin 20210A seems to be associated with unexplained ischemic myelopathy among the young women with estrogens.