Diffusion-weighted magnetic resonance imaging of normal and degenerative lumbar intervertebral discs: a new method to potentially quantify the physiologic effect of physical therapy intervention

STUDY DESIGN: Observational, repeated measures design. OBJECTIVES: To determine the reliability of the apparent diffusion coefficient (ADC) calculated from diffusion-weighted magnetic resonance images (MRI) of the nuclear region of lumbar intervertebral discs (IVDs), to investigate the differences in the ADC based upon T2-signal intensity, and to examine the test-retest variation in these measures obtained from subjects undergoing serial, diffusion-weighted MRI scans. BACKGROUND: Impaired diffusion of water within the lumbar IVD is a central characteristic of degenerative disc disease. Diffusion-weighted MRI scans can provide quantitative estimates of water diffusion and may be useful to evaluate the physiologic effects of healing or the change in hydration related to interventions such as traction, manual therapy, or exercise on normal and degenerative lumbar IVDs. METHODS AND MEASURES: Thirty subjects underwent T2 -weighted and diffusion-weighted lumbar MRI scans. Twenty-one of these subjects underwent a second diffusion-weighted MRI scan 4 to 7 weeks after the initial scan. The ADC was calculated from midsagittal diffusion-weighted images for the IVDs of L1-2 to L5-S1. To assess reliability, repeated measures of the ADC were performed on the first 16 scans. The T2-signal of the nuclear region of each disc was classified as hyperintense, intermediate, or hypointense, and its relationship to the mean ADC of the nuclear region was determined. Test-retest variation in the ADC was described using the coefficient of variation (CV), plus or minus the width of the 95% confidence interval of the standard error of measurement (SEM). RESULTS: Intraclass correlation coefficients for estimates of intrarater and interrater reliability ranged from 0.95 to 0.99 and the SEM ranged from 0.006 to 0.026 X 10-3 mm2/s. The mean ADC was significantly greater for hyperintense IVDs compared to intermediate and hypointense IVDs. The CV plus or minus the 95% CI of the SEM between scans ranged from 9.0% to 13.6% for all discs, 6.1% to 10.1% for hyperintense discs, and 13.1% to 23.7% for intermediate discs. The prevalence of hypointense discs was too low to make meaningful judgments about their normal degree of variation over time. CONCLUSION: The ADC of the nuclear region of the lumbar IVDs may be reliably measured from diffusion-weighted images. Degenerative discs had lower mean ADC values than normal discs but demonstrated greater variation between scans. Diffusion-weighted imaging may be a useful procedure to assess change in diffusion of water in lumbar discs that occurs over time.     

Influence of a platelet concentrate on prosthetic bone ingrowth in a rabbit model

Recent studies have shown that an increase in bone ingrowth by addition of osteogenic growth factors can reduce micro motion and gross implant motion and contribute to joint implant stability through osseointegration. Platelet-rich plasma (PRP) has the potential to provide growth factors that may be conducive to osteointegration at the bone-implant interface. This study analyzed the influence of PRP on bone ingrowth upon a beaded metal implant in distal femurs of 22 rabbits. Rabbit limbs were randomly assigned to receive an implant plus PRP or plain implant. Half of the specimens were randomly assigned to a 2-week group (n = 20) or a 5-week group (n = 20). Histologic and histomorphometric comparison between implant alone and implant plus PRP, at 2 and 5 weeks, was performed. In both the 2- and 5-week comparisons, there was no statistical difference (p > .05) in bone ingrowth between the control and PRP group, despite a slight increase in trabecular bone growth in PRP groups. This study suggests that PRP is not a major contributing factor to bone ingrowth at the bone-implant interface. This supports growing evidence in the literature that PRP can lead to variable bone growth stimulation in vivo.     

The contralateral foot in children with unilateral clubfoot: a study of pressures and forces involved in gait

The unaffected contralateral side of patients with unilateral clubfeet has sometimes been taken as control in foot pressure measurement studies. However, it has never been shown that the pressure pattern under the contralateral foot is similar to a normal foot. Sixteen patients with unilateral clubfoot and 110 normal subjects took part in this study. All participants were aged from 4 to 8 years. Studies comprised clinical examination and foot pressure measurements in barefoot walking. Evaluations of the measurements were completed by the calculation of forces acting under 10 anatomical foot areas normalized to ground reaction force at foot-flat and push-off. Significant differences in peak pressure were observed between the control group and the contralateral foot of patients under the heel and the metatarsals 1 to 4. Significant differences in the forces at foot-flat and push-off are seen especially in the midfoot. Both sides of the patients with unilateral clubfeet exert significantly less ground reaction force than normal subjects. Different pressure and force distributions of clubfoot children on their contralateral side compared with the normal feet of the control group may indicate differences in the general control pattern generated by the central nervous system. Differences can still be observed after normalization of the forces. We therefore conclude that when foot pressure measurements are made with clubfeet, it might be advisable to use a collective of normal feet, instead of the contralateral foot, for comparison.     

A preoperative prognostic nomogram for solid enhancing renal tumors 7 cm or less amenable to partial nephrectomy

PURPOSE: Small renal masses are increasing in incidence. Most tumors 7 cm or less are treated with radical or partial nephrectomy but clinicians are increasingly relying on ablative therapies and observation for some small renal masses. We present novel nomograms that predict the likelihood of benign, likely indolent or potentially aggressive pathological findings based only on readily identifiable preoperative factors. MATERIALS AND METHODS: Information on all partial nephrectomies performed at a single institution was collected in an institutional review board approved registry. Using retrospectively collected data on all 862 patients who underwent partial nephrectomy for a single, solid, enhancing, clinical T1 (7 cm or less) tumor between 1999 and 2005 tumors were classified as benign or malignant. Grade 3 clear cell renal cell carcinoma, grade 4 renal cell carcinoma of any type and any renal cell carcinoma with vascular, fat or collecting system invasion were considered potentially aggressive. The likelihood of benign, likely indolent or potentially aggressive pathological findings was modeled using multivariable logistic regression models based on age, gender, radiographic tumor size, symptoms at presentation and smoking history. RESULTS: Of 862 small renal masses 20% were benign and 80% were malignant but only 30% of cancers (24% of small renal masses) were potentially aggressive. All 11 patients with systemic symptoms had cancer. The remaining 851 patients underwent further analysis. Factors that were most strongly associated with the likelihood of benign pathology were age, gender, tumor size and smoking history. A nomogram constructed to predict benign histology proved to be relatively accurate and discriminating (bootstrap corrected concordance index 0.644) and calibrated. Small renal masses in older men and younger women were more likely to be benign. With regard to differentiating indolent from potentially aggressive cancers, only advanced age was independently significant on multivariate analysis (p <0.005). The nomogram for this outcome performed with limited ability (concordance index 0.557). CONCLUSIONS: Clinical factors provide substantial predictive ability to predict benign vs malignant pathology for small renal masses amenable to partial nephrectomy. Although most of these small renal masses are benign or indolent, our ability to predict potentially aggressive cancer in this population remains limited.     

Partially Overlapping Limited Anterior and Posterior Instrumentation for Adult Thoracolumbar and Lumbar Scoliosis: A Description of Novel Spinal Instrumentation, “The Hybrid Technique”

Progressive and/or painful adult spinal deformity in the thoracolumbar and lumbar spine is sometimes treated surgically by long posterior fusions from the thoracic spine down to the pelvis, especially where there is a major thoracic curve component. Recent advances in anterior spinal instrumentation and spinal surgery technique have demonstrated the improved corrective ability offered by anterior stabilization systems, and the added benefit of limiting the number of vertebral fusion levels required for control of the deformity. The "hybrid technique" is a novel use of anterior instrumentation that applies limited anterior instrumentation down to the low lumbar spine (rods and screws), and partially overlapping short-segment posterior instrumentation to the sacrum (pedicle screws and rods). These constructs avoid posterior thoracic instrumentation and fusions, and avoid extension of posterior instrumentation to the pelvis. In the first 10 patients treated using this technique, thoracolumbar and lumbar major curve correction has averaged 71 and 82% in the immediate postoperative period (n = 7), respectively, and 59 and 68% at 2-year follow-up, respectively. The technique is an appealing and attractive alternative for treatment of thoracolumbar and lumbar scoliosis in the adult population, and avoids the requirement for applying spinal fixation to the thoracic spine and the pelvis.     

Resistance exercise: a strategy to attenuate inflammation and protein-energy wasting in hemodialysis patients?

Purpose

Patients undergoing hemodialysis (HD) present persistent inflammation and protein-energy wasting (PEW), which contributes to high rates of mortality. This study aimed to assess the effects of a resistance exercise training program (RETP) on inflammation and PEW in HD patients.

Methods

Thirty-seven patients (56.7 % men, 45.9 ± 14.1 years, 23.5 ± 3.9 kg/m²) performed 6 months of intradialytic RETP. Plasma adhesion molecules levels (ICAM-1 and VCAM-1) were measured using the enzyme immunometric assay, and interleukin-6 (IL-6), C-reactive protein, and tumor necrosis factor-alpha by ELISA. Anthropometric, physical capacity, and PEW (simultaneously presence of: BMI <23 kg/m², serum albumin <3.8 g/dL, and reduced arm muscle area) were analyzed.

Results

There was a reduction of ICAM-1 [(1,934.1 pg/mL (1,031.8–2,875.0) vs. 1,571.1 pg/mL (447.1–2,985.5), p < 0.05], VCAM-1 [5,259.51 pg/mL (3,967.4–6,682.4) vs. 3,062.11 pg/mL (2,034.0–5,034.4), p < 0.05], and CRP levels (2.3 ± 0.9 to 1.6 ± 0.6 pg/mL, p < 0.001) after 6 months of RETP. Body composition improved, albumin increased (3.7 ± 0.3 to 3.9 ± 0.2, p < 0.05), and the number of patients presenting PEW was decreased (p = 0.005).

Conclusions

Resistance exercise program for 6 months seems to be effective in reducing inflammation and PEW of HD patients. The universal trial number of this study is U1111-1139-1326.     

Trabecular Bone Score and Hip Structural Analysis in Patients With Atypical Femur Fractures

Bisphosphonate use has declined dramatically in recent years, partly because of fear of rare side effects like atypical femur fractures (AFFs). It is therefore desirable to have a diagnostic method to identify those at risk of AFF to prevent this serious complication. We compared trabecular microarchitecture and hip geometry between 30 patients with AFF and 141 controls of similar age and sex, using bisphosphonates. Trabecular bone score (TBS) and hip structural analysis (HSA) were used to assess trabecular microarchitecture and macroscopic hip geometry from dual-energy X-ray absorptiometry images of the lumbar spine and hip, respectively. General characteristics, TBS, and HSA were compared between patients with AFF and controls using Student's t tests and chi-square statistics. Associations between AFF and TBS and femur geometric characteristics by HSA were adjusted for sex, age, height, weight, ethnicity, duration of bisphosphonate use, and glucocorticoid use. Additionally, the analysis of TBS was adjusted for lumbar spine bone mineral density and the time difference between dual-energy X-ray absorptiometry scanning and the diagnosis of AFF. Patients with AFF had significantly higher body mass index than controls, had used bisphosphonates longer, and glucocorticoids and proton pump inhibitors more frequently. Sex-specific T-score was significantly higher in patients with AFF at the lumbar spine (p?=?0.004), but not at the femoral neck (p?=?0.190) after adjustment for age, height, and weight. TBS did not differ significantly between patients with AFF and controls. Neither neck shaft angle nor any geometric variables at the femoral shaft measured by HSA differed between patients with AFF and controls. At the narrow neck, patients with AFF had lower buckling ratio and higher centroid position, consistent with a lower risk of classical fragility hip fractures. The findings at narrow neck and higher bone mineral density might be explained by the fact that the majority of patients with AFF used bisphosphonates to prevent glucocorticoid-induced osteoporosis. Based on our results, TBS and HSA do not appear to have value in detecting patients at risk of AFF.     

Postoperative infection in cochlear implant patients.

OBJECTIVE: Recently, the association of meningitis with cochlear implants has raised concern over the safety of these devices. We examined the incidence of all postoperative infections in patients undergoing cochlear implant surgery.Study design and settings A retrospective chart review of all patients undergoing cochlear implants at a private tertiary referral center from 1993 to 2002 was performed. Cochlear implant surgeries in 462 adults and 271 children were reviewed. Patients with evidence of a postoperative infection or infectious complication related to cochlear implantation were identified, and data on patient characteristics, surgery, and treatment outcome were obtained. RESULTS: The overall incidence of postoperative infection in our cochlear implant series was 4.1%. Major infectious complications occurred in 3.0% of cases, and the majority of infections required surgical intervention. A history of chronic ear disease may increase the risk of infectious complications. There were no cases of meningitis. CONCLUSIONS: Cochlear implants remain a safe procedure with a low complication rate. The majority of infections can be managed without removing the implant device. Advances in surgical technique and flap design have decreased the occurrence of wound-related complications. However, identification of risk factors for infection and optimization of treatment regimens will further reduce the complications associated with postoperative infection.     

Isolation of a cDNA clone for the liver cell adhesion molecule (L-CAM).

Liver cell adhesion molecule (L-CAM) is a calcium-dependent cell adhesion molecule found in very early vertebrate embryos and on liver and other epithelial cells in adults. To describe the genes coding for the molecule and study its synthesis, we have cloned cDNA from poly(A)+ RNA of 10-day embryonic chicken liver using the delta gt11 expression vector. One clone, lambda L301, has been characterized and used in analyses of L-CAM mRNA and genomic DNA. Clone lambda L301 produced a fusion protein that reacted strongly with polyclonal antibodies that recognize L-CAM (Mr 124,000) and its Mr 81,000 NH2-terminal fragment, Ft1, released from liver membranes by trypsin. This result indicates that lambda L301 contains a cDNA insert complementary to protein coding sequence within the two-thirds of the mRNA coding region beginning at the 5' end. The 220-base-pair cDNA insert was isolated and used as a probe in hybridization experiments. RNA transfer blot analysis of poly(A)+ RNA showed a single 4-kilobase mRNA; Southern blot analysis showed multiple components consistent with the presence of one to three L-CAM genes. To test whether different tissues express different forms of L-CAM message, poly(A)+ RNA from eight embryonic organs was analyzed. Only organs that expressed L-CAM protein contained poly(A)+ RNA that hybridized to the lambda L301 probe; in all cases a single band, with the same mobility as that in liver, was observed. The L-CAM mRNA in each tissue was present in proportions similar to those detected previously for the L-CAM protein in these tissues. The combined results suggest that any possible heterogeneity in the L-CAM genes is not reflected in the size of either the mRNA or protein.