Thoracic pedicle screw fixation in spinal deformities: are they really safe?

STUDY DESIGN: A retrospective study. OBJECTIVE: To determine the safety of pedicle screw fixation in thoracic deformity correction. SUMMARY OF BACKGROUND DATA: Pedicle screw fixation enables enhanced correction of spinal deformities. However, the technique is still not widely applied for thoracic deformities for fear of neurologic complications. MATERIALS AND METHODS: A total of 462 patients subjected to thoracic pedicle screw fixation for spinal deformities were analyzed after a minimum follow-up of 2 years. Etiologic diagnoses were idiopathic scoliosis in 330, congenital kyphoscoliosis in 68, kyphosis in 50, and others in 14. They were reviewed using the medical records and preoperative, intraoperative, and postoperative roentgenograms. Computed tomography was performed when screw position was questionable. RESULTS: A total of 4604 thoracic pedicle screws were inserted (10.1 screws/patient). There were 67 screw malpositions (1.5%) in 48 patients (10.4%). The malpositions were inferior in 33, lateral in 18, superior in 12, and medial in 4. Screw-related neurologic complications occurred in four patients (0.8%); these comprised a transient paraparesis and three dural tears. Other complications comprised 11 intraoperative pedicle fractures, 35 screw loosenings, 9 postoperative infections, and 1 pneumothorax. There were no significant screw-related neurologic or visceral complications that adversely affected the long-term result. The deformity correction was 69.9% for idiopathic scoliosis and 60.7% for congenital scoliosis. The sagittal plane deformity correction was 47 degrees for kyphosis. CONCLUSIONS: Thoracic pedicle screw fixation is a reliable method of treating spinal deformities, with an excellent deformity correction and a high margin of safety.     

Quantification of proteinuria in children using the urinary protein-osmolality ratio

A prospective study was conducted to determine the correlation of early morning urinary protein/osmolality ratio (mg/l/mosmol/kg) with 24-h urinary protein excretion (mg/m²/day). Study patients consisted of 53 children (aged 1 month to 15 years). Early morning urine samples and 24-h urine samples were collected and analyzed. In group 1 (children without proteinuria), early morning urinary protein/creatinine ratio (Uprot/Ucr, mg/mg) was 0.061±0.011 and the protein/osmolality ratio (Uprot/Uosm, mg/l/mosmol/kg) was 0.073±0.014. Twenty-four hour urinary protein excretion in group 1 had no significant correlation with Uprot/Ucr or Uprot/Uosm. In group II (children with proteinuria), Uprot/Ucr was 5.78±1.10 and Uprot/Uosm was 4.42±1.34. Twenty- four hour urinary protein excretion in group 2 was 1483.6±303.7 mg/m²/day and its correlation with both Uprot/Uosm and Uprot/Ucr was highly significant (r= 0.87, P<0.001 and r=0.88, P<0.001, respectively). The accepted nephrotic level of proteinuria of 40 mg/m²/h coincides with a Uprot/Uosm ratio of 1.9. In conclusion, early morning urinary Uprot/Uosm is a simple and potentially useful test for 24-h urinary protein excretion, and possibly could be used safely for the assessment of the degree of proteinuria in children. Received: 13 April 1999 / Revised: 23 February 2000 / Accepted: 15 August 2000     

Should laparoscopy be the standard approach used for pelvic lymph node dissection?

Involvement of the pelvic lymph nodes in patients with prostate cancer worsens the overall prognosis of this common disease entity. Prior radiographic staging tech-niques, including fine-needle aspiration, are limited by a poor sensitivity and are not reliable. The gold standard for the evaluation of pelvic lymph nodes in men with prostate cancer involves performing a lymphadenectomy. Historically, this procedure was performed using an open surgical technique. Unfortunately, this invasive procedure is associated with significant morbidity. In response, modern surgical technology has provided newer, less invasive techniques, including laparoscopic pelvic lymphadenectomy (LPLND). Improved detection of localized prostate cancer through the institution of screening protocols and early detection programs has decreased the number of patients presenting with lymph node involvement. Various clinical indicators, including prostate-specific antigen, grade, and stage, have been used to improve the selection of “high-risk” patients that are appropriate candidates for pelvic lymph node dissection. The technique of LPLND is a valid option in the armamentarium for staging of prostate cancer. The laparoscopic approach provides the same staging accuracy as the open surgical technique and is superior with respect to morbidity. LPLND is limited to patients who present with a high risk of advanced prostate cancer. In addition, the urologist must accept the additional training, financial expense, and “learning curve” associated with this technique.     

The prevalence of chronic prostatitis-like symptoms in young men: a community-based survey

We surveyed the prevalence of chronic prostatitis-like symptoms in young men using the National Institutes of Health (NIH) Chronic Prostatitis Symptom Index (CPSI) and determined the clinical validity of the NIH-CPSI among men in the community. Of 29,017 men aged 20 years dwelling in the community, 8,705 men were randomly selected at a 30.0% sampling fraction and a total of 6,940 men (a response rate 79.7%) completed a self-administered questionnaire. Six percent reported having pain or discomfort in more than one area . About 5% did not feel that the bladder emptied fully after urinating more than 1 time in 5 and 10.5% had to urinate again within 2 h more than 1 time in 5. As the scores for pain or discomfort increased, those for urinary symptoms and impact on quality of life increased (P < 0.001; Armitage test). As the scores for urinary symptoms increased, those for pain or discomfort and impact on quality of life also increased (P < 0.001; Armitage test). The community-based prevalence of chronic prostatitis-like symptoms were found to be high in young men as well as in older men. Our findings indicate that men with pain or urinary symptoms experience a negative impact on their quality of life and the NIH-CPSI provides a valid measure for the general population. Received: 19 September 2000 / Accepted: 23 November 2000     

The cytotoxic effect of methotrexate loaded bone cement on osteosarcoma cell lines

We mixed various amounts of methotrexate with bone cement and measured the absorbance daily for 4 weeks. The cytotoxic effects on SaOS2 and MG63 osteosarcoma cells were examined by the MTT assay, and analysed according to the methotrexate concentration and the elapsed time. The amount of eluted methotrexate was greatest during the first day, and then decreased rapidly reaching a plateau in the third week. The number of viable tumour cells decreased significantly after 72 h, and they were hardly seen after 1 week.     

Quantitative immunoelectron microscopy of type VI collagen in glomeruli in type I diabetic patients

BACKGROUND: The nature of the extracellular matrix (ECM) accumulating in the glomerular basement membrane (GBM) and mesangium (Mes) in diabetes is unknown. Type IV collagen (Col IV) as estimated by quantitative immunoelectron microscopy was reduced in type I diabetic patients (D) with rapid ("fast-track") compared with slow ("slow-track") development of diabetic nephropathy (DN) lesions and controls (C). Col VI is another ECM component suggested to account for Mes matrix (MM) expansion in DN. METHODS: Col VI ECM density was evaluated in eight "slow-track" {Mes fractional volume [Vv(Mes/glom)] <0.32, duration> 20 years} and seven "fast-track" patients [Vv(Mes/glom)> 0.37, duration <20 years diabetes] and in eight C. Quantitative immunoelectron microscopy was performed using polyclonal antibodies to Col VI. Gold particle density (PDG) in MM and the inner layer (IL) of the GBM was measured using stereologic methods. RESULTS: GBM IL PDG was decreased in both fast-track (1.7 +/- 1.6/microm2, mean +/- SD, P < 0.002) and slow-track (3.9 +/- 2.4, P < 0.02) D versus C (10.8 +/- 7.9). GBM IL PDG was also lower in the fast-track versus slow-track D (P < 0.04). Mes matrix PDG/microm2 was decreased in fast-track D (3.2 +/- 3.6) versus C (14.1 +/- 14.6, P < 0.02); a similar trend was seen in slow-track D (5.7 +/- 5.6, P < 0.1). There was no significant difference in MM PDG between the slow-track and fast-track D. CONCLUSION: Col VI density in MM and GBM is decreased in diabetic patients with slowly and rapidly developing renal lesions. This leaves the nature of ECM accumulation in DN unexplained. At least in part, glomerular ECM compositional change is related to diabetes per se and may be independent of the severity of lesions.     

Computer-assisted thoracic pedicle screw placement: an in vitro feasibility study

STUDY DESIGN: In this cadaveric study, a computer-assisted image guidance system was tested for accuracy of thoracic pedicle screw placement. OBJECTIVES: Evaluate the system's accuracy for thoracic pedicle screw placement in vitro. SUMMARY OF BACKGROUND DATA: The effective use and reliability of pedicle screw instrumentation in providing short-segment stabilization and correction of deformity is well known in the lumbar spine. Pedicle screw placement in the thoracic spine is difficult because of the small dimensions of the thoracic pedicles and risk to the adjacent spinal cord and neurovascular structures. Investigators have shown the improved accuracy of computer-assisted lumbar pedicle screw placement; but the accuracy of computer-assisted thoracic pedicle screw placement, which is becoming more widely used, has not been shown. METHODS: In five human cadavers, 120 thoracic pedicle screws were placed with computer-assisted image guidance. The largest clinically feasible screw was used based on the cross-sectional dimensions of each pedicle. The accuracy was assessed by postoperative computed tomography and visual inspection. RESULTS: The overall pedicle cortex violation was 23 of 120 pedicles (19.2%). Nine violations (7.5%) were graded as major and 14 (11.7%) as minor. A marked and progressive learning curve was evident with the perforation rates that decreased from 37.5% in the first cadaver to 4.2% in the last two cadavers. CONCLUSIONS: Accurate thoracic pedicle screw placement is feasible with computer-assisted surgery. However, as with any other new surgical technology, the learning curve must be recognized and incorporated into the necessary fundamental knowledge and experience for these procedures.     

Mice lacking Raf kinase inhibitor protein-1 (RKIP-1) have altered sperm capacitation and reduced reproduction rates with a normal response to testicular injury

Raf kinase inhibitor protein-1 (RKIP-1) belongs to the phosphatidyl ethanolamine-binding family of proteins (PEBP), which are highly conserved throughout evolution and widely expressed in tissues of mammalian organisms. RKIP-1 is a modulator of extracellular signal-regulated kinase (ERK), nuclear factor-kappa B (NF-kappaB), and G protein coupled receptor (GPCR) signaling cascades and is implicated as a factor in numerous physiological processes and disease states including metastasis. Testicular germ cells also express high levels of RKIP mRNA during spermatogenesis, particularly from late pachytene spermatocytes through step 15 elongate spermatids. Therefore, the sensitivity of spermatogenesis to injury was compared in wild-type and RKIP-1(-/-) mice. Unlike what has been described with tumor suppressors such as p53, RKIP-1(-/-) and wild-type mice were equally sensitive to germ cell toxicity by x-irradiation as assessed by terminal deoxynucleotidyl transferase biotin-deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) positivity 9 hours after a 5 Gy exposure and testicular spermatid head counts 15.5 days after 0.5 Gy exposure. Recent findings also indicate that RKIP is a decapacitation factor receptor on sperm. The present study demonstrates that sperm from RKIP-deficient mice are precociously capacitated compared with their wild-type counterparts. Data from mating experiments indicate decreased reproduction rates between crosses of RKIP-1(-/-) male mice and either heterozygous or RKIP-1(-/-) females. Furthermore, RKIP immunolocalization of epididymal sperm supports transfer of the protein from germ cell cytoplasm to the sperm via the cytoplasmic droplet during epididymal transport. Overall, these studies indicate an important role for RKIP in reproduction as a modulator of capacitation but not in the regulation of testicular injury.