Have Referral Patterns for Vertebroplasty Changed since Publication of the Placebo- Controlled Trials?

BACKGROUND AND PURPOSE: Our aim was to determine whether referral patterns and rates of vertebroplasties at the Mayo Clinic have changed after the publication of the INVEST and the Australian Trial. In August of 2009, we performed a retrospective review of patients undergoing vertebroplasties and those patients who were referred for but did not receive vertebroplasties before and after the recently published placebo-controlled vertebroplasty trials. MATERIALS AND METHODS: After approval by our local institutional review board, we retrospectively evaluated all patients referred for vertebroplasty between January 5, 2004, and June 2, 2010. We catalogued age, sex, number of treated vertebrae, physician referring the patient for vertebroplasty, and the referring department. We calculated the mean number of referrals per month before and after August 2009, which was the month of publication for both trials. We also calculated rates for specific referring physician types. RESULTS: During the full study, 1188 patients were referred, of whom 807 underwent treatment at 1378 levels for a total of 943 separate vertebroplasty procedures. The mean number of vertebroplasty referrals per month has dropped significantly from 18.9 ± 5.3 (95% CI, 17.7-20.2) before publication to 11.3 ± 3.1 (95% CI, 9.1-13.5) referrals per month after publication (P=.0001). Before publication, 67.3 ± 14.0% (95% CI, 64.0%-70.7%) of patients referred for vertebroplasty underwent vertebroplasty, compared with 76.0 ± 14.9% (95% CI, 65.4%-86.6%) after publication (P=.11). CONCLUSIONS: The number of vertebroplasty referrals at our center has decreased significantly since the publication of INVEST and the Australian Trial, yet we continue to offer the procedure to a high proportion of referred patients

Stiff Polymers, Foams and Fiber Networks

We study the elasticity of fibrous materials composed of generalized stiff polymers. It is shown that in contrast to cellular foam-like structures affine strain fields are generically unstable. Instead, a subtle interplay between the architecture of the network and the elastic properties of its building blocks leads to intriguing mechanical properties with intermediate asymptotic scaling regimes. We present exhaustive numerical studies based on a finite element method complemented by scaling arguments.Comment: 4 pages, 5 figure

Unfolding cross-linkers as rheology regulators in F-actin networks

We report on the nonlinear mechanical properties of a statistically homogeneous, isotropic semiflexible network cross-linked by polymers containing numerous small unfolding domains, such as the ubiquitous F-actin cross-linker Filamin. We show that the inclusion of such proteins has a dramatic effect on the large strain behavior of the network. Beyond a strain threshold, which depends on network density, the unfolding of protein domains leads to bulk shear softening. Past this critical strain, the network spontaneously organizes itself so that an appreciable fraction of the Filamin cross-linkers are at the threshold of domain unfolding. We discuss via a simple mean-field model the cause of this network organization and suggest that it may be the source of power-law relaxation observed in in vitro and in intracellular microrheology experiments. We present data which fully justifies our model for a simplified network architecture.Comment: 11 pages, 4 figures. to appear in Physical Review

Asymptomatic and Unrecognized Cement Pulmonary Embolism Commonly Occurs with Vertebroplasty

BACKGROUND AND PURPOSE: Cement PE represents a potentially serious complication following vertebroplasty. To determine the frequency and extent of cement PE during percutaneous vertebroplasty, we performed a retrospective review of chest CT scans obtained in patients who had previously undergone ≥1 vertebroplasty procedure. MATERIALS AND METHODS: After approval by our local institutional review board, we retrospectively evaluated 244 patients who had undergone vertebroplasty at 465 levels and subsequently underwent chest CT. A thoracic radiologist evaluated the presence, number, size, and location of discrete cement PEs. We catalogued the following data: age, sex, number of treated vertebrae, cement volume per vertebra, operator, presence of cement leakage noted by the operator during the procedure, and clinical presentation at postvertebroplasty CT. RESULTS: At least 1 cement PE was detected in 23 (9.4%; 95% CI, 6%-13%) of 244 patients; 1 patient was symptomatic from a cement PE. The mean number of discrete cement PEs was 3.2 ± 3.4 (median, 2; range, 1-12). There was no correlation among the total number of treatment sessions, number of levels treated per session, cement volume per level, operator, or time between vertebroplasty and chest CT in the detection of cement PE. Those with PE were significantly younger (P=.0229) and had significantly more total levels treated (P=.0260). Cement PE was recognized by the operator during the vertebroplasty in 2 (8.7%) of 23 patients found to have it on CT. CONCLUSIONS: Small asymptomatic cement PEs are common during vertebroplasty and usually are not recognized by the operator during the procedure

Discharge disposition following vertebroplasty

BACKGROUND AND PURPOSE: A variety of factors, such as pain level at rest and with activity, have been used to assess outcome of the VP procedure. However, few studies have assessed discharge disposition as a reflection of VP efficacy in the inpatient population. The purpose of this study was to compare patient disposition status before and after VP and determine what relationship exists between the treatment and patient discharge status

Primary pyogenic spondylitis following kyphoplasty: a case report

<p>Abstract</p> <p>Introduction</p> <p>Only ten cases of primary pyogenic spondylitis following vertebroplasty have been reported in the literature. To the best of our knowledge, we present the first reported case of primary pyogenic spondylitis and spondylodiscitis caused by kyphoplasty.</p> <p>Case presentation</p> <p>A 72-year old Caucasian man with an osteoporotic compression fracture of the first lumbar vertebra after kyphoplasty developed sensory incomplete paraplegia below the first lumbar vertebra. This was caused by myelon compression following pyogenic spondylitis with a psoas abscess. Computed tomography guided aspiration of the abscess cavity yielded group C <it>Streptococcus</it>. The psoas abscess was percutaneously drained and laminectomy and posterior instrumentation with an internal fixator from the eleventh thoracic vertebra to the fourth lumbar vertebra was performed. In a second operation, corpectomy of the first lumbar vertebra with cement removal and fusion from the twelfth thoracic vertebra to the second lumbar vertebra with a titanium cage was performed. Six weeks postoperatively, the patient was pain free with no neurologic deficits or signs of infection.</p> <p>Conclusion</p> <p>Pyogenic spondylitis is an extremely rare complication after kyphoplasty. When these patients develop recurrent back pain postoperatively, the diagnosis of pyogenic spondylitis must be considered.</p

Screening for brain aneurysm in the Familial Intracranial Aneurysm study: frequency and predictors of lesion detection

Object Approximately 20% of patients with an intracranial saccular aneurysm report a family history of intracranial aneurysm (IA) or subarachnoid hemorrhage. A better understanding of predictors of aneurysm detection in familial IA may allow more targeted aneurysm screening strategies. Methods The Familial Intracranial Aneurysm (FIA) study is a multicenter study, in which the primary objective is to define the susceptibility genes related to the formation of IA. First-degree relatives (FDRs) of those affected with IA are offered screening with magnetic resonance (MR) angiography if they were previously unaffected, are ≥ 30 years of age, and have a history of smoking and/or hypertension. Independent predictors of aneurysm detection on MR angiography were determined using the generalized estimating equation version of logistic regression. Results Among the first 303 patients screened with MR angiography, 58 (19.1%) had at least 1 IA, including 24% of women and 11.7% of men. Ten (17.2%) of 58 affected patients had multiple aneurysms. Independent predictors of aneurysm detection included female sex (odds ratio [OR] 2.46, p = 0.001), pack-years of cigarette smoking (OR 3.24 for 20 pack-years of cigarette smoking compared with never having smoked, p < 0.001), and duration of hypertension (OR 1.26 comparing those with 10 years of hypertension to those with no hypertension, p = 0.006). Conclusions In the FIA study, among the affected patients’ FDRs who are > 30 years of age, those who are women or who have a history of smoking or hypertension are at increased risk of suffering an IA and should be strongly considered for screening