Intraoperative radiation therapy with 50 kV x-rays: A multi-institutional review.

This report covers clinical implementation of a low kV intraoperative radiation therapy (IORT) program with the INTRABEAM® System (Carl Zeiss Meditec AG, Jena, Germany). Based on collective user experience from eight institutions, we discuss best methods of INTRABEAM quality assurance (QA) tests, commissioning measurements, clinical workflow, treatment planning, and potential avenues for research. The guide provides pertinent background information and clinical justification for IORT. It describes the INTRABEAM system and commissioning measurements along with a TG100 risk management analysis to ensure safety and accuracy of the IORT program. Following safety checks, dosimetry measurements are performed for verification of field flatness and symmetry, x-ray output, and depth dose. Also discussed are dose linearity checks, beam isotropy, ion chamber measurements, calibration protocols, and in-vivo dosimetry with optically stimulated luminescence dosimeters OSLDs, and radiochromic film. Emphasis is placed on the importance of routine QA procedures (daily, monthly, and annual) performed at regular intervals for a successful IORT program. For safe and accurate dose delivery, tests of important components of IORT clinical workflow are emphasized, such as, dose prescription, pre-treatment QA, treatment setup, safety checks, radiation surveys, and independent checks of delivered dose. Challenges associated with in-vivo dose measurements are discussed, along with special treatment procedures and shielding requirements. The importance of treatment planning in IORT is reviewed with reference to a Monte Carlo-based commercial treatment planning system highlighting its main features and limitations. The report concludes with suggested topics for research including CT-based image-guided treatment planning and improved prescription dose accuracy. We hope that this multi-institutional report will serve as a guidance document on the clinical implementation and use of INTRABEAM IORT.

Lead toxicity and management of gunshot wounds in the lumbar spine.

INTRODUCTION: Gunshot wounds are one of the commonest causes of spinal injury. Management of these patients differs from other blunt trauma injuries to the spine. We present a case of a gunshot wound to the lumbar spine that occurred in 1985 which was treated non-operatively. METHODS: In the last 10 years, the patient was admitted multiple times for confusion and lead toxicity with blood levels over 100 µg/dl. Inpatient chelation therapy was implemented. After multiple recommendations for surgery, the patient agreed to have as much of the bullet removed as possible. The patient successfully underwent decompression and fusion from both anterior and posterior approaches. Lead levels subsequently declined. CONCLUSION: The purpose of this paper is to show a case of a gunshot wound to the spine that ultimately caused plumbism and required surgery. Technical aspects of the surgery are described as well as pre- and post-procedural imaging. Recommendations for the general management of spine gunshot wounds are also described.

Neuroforaminal Stenosis in the Lumbosacral Spine: A Scoping Review of Pathophysiology, Clinical Manifestations, Diagnostic Imaging, and Treatment.

OBJECTIVE: To conduct the first scoping review of lumbosacral neuroforaminal stenosis with respect to the pathophysiology, symptomatic manifestations, diagnostic imaging, and treatment options. METHODS: A scoping literature review was conducted in accordance with the recommendations set forth by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), with English language restrictions stipulated to include articles pertaining to lumbosacral neuroforaminal stenosis. Databases maintained by PubMed, National Library of Medicine, Cochrane Central Register of Controlled Trials (Ovid), Scopus (Elsevier), Web of Science (Thomson Reuters), and Google Scholar were queried from their inception date through December 2022. SUMMARY OF THE EVIDENCE: A total of 276 articles were reviewed and 29 articles were included within the study. Within these articles, the anatomic origins of neuroforaminal stenosis were reviewed in detail and the resulting clinical manifestations were discussed. Recent studies evaluating the efficacy of existing diagnostic imaging modalities were summarized, along with potential future methods to improve sensitivity for detecting this entity and measuring foraminal stenosis via novel imaging techniques. Based on the literature, the conservative management and surgical treatment of lumbosacral foraminal stenosis were discussed. CONCLUSIONS: Lumbar neuroforaminal stenosis represents a significant source of radicular pain that is often compounded by delayed diagnosis and incomplete treatment. This article represents the first scoping review of lumbosacral neuroforaminal stenosis with focus on diagnosis, management, and treatment for associated radicular pain. The goal is to reduce the incidence of untreated or unrecognized neuroforaminal stenosis in the setting of a complex decompression and fusion, as well as to promote minimally invasive surgery to address radicular pain from neuroforaminal stenosis. Recent advances in diagnostic imaging and surgical techniques have the potential to improve the timeliness and durability of patients' treatment options. Future directions for the diagnostic imaging of foraminal stenosis include efforts aimed at developing the nascent field of computerized mapping to reliably quantify stenosis and its impact on the exiting nerve root and associated dorsal root ganglia.

Resource Allocations for Common Radiation Oncology Procedures.

PURPOSE: Radiation Oncology is a complex, resource-intensive discipline. The complexity of the radiation oncology treatment process has increased significantly in recent years with the introduction of more advanced imaging, planning, and treatment delivery technology and enhanced use of multidisciplinary care paths. We conducted a multi-institutional study to estimate the average time by functional unit for a wide range of modern radiation oncology treatment regimens. METHODS AND MATERIALS: Structured process mapping was performed for 24 treatment categories, and average time estimates for 6 functional groups were obtained for each process step through consultation with the full clinical team at each institution. Six geographically dispersed institutions participated in the study. Significant effort was invested in aggregate data analysis and clarification of assumptions. RESULTS: The findings show significant variability in the resources expended for many treatment categories as well as the distribution of workload between functional units. Major factors in the variability include the rate of adoption of hypofractionation in external beam therapy, adoption of automation tools and standardization, and the transition to multimodality image-based planning in brachytherapy. CONCLUSIONS: The data obtained from this study may be useful in designing institution-specific staffing models appropriate to the scope of radiation therapy services provided at each institution.

MRI-guided Real-time Online Gated Stereotactic Body Radiation Therapy for Liver Tumors.

BACKGROUND: Liver tumors are commonly encountered in oncology. The study aimed to assess the impact of magnetic resonance imaging (MRI)-guided stereotactic body radiation therapy (SBRT) (MRgSBRT) on disease-related outcomes and the toxicity profile. METHODS: Patients who received MRgSBRT from 2019 to 2021 for primary and metastatic liver tumors were included in this analysis. The protocol for treatment simulation included Gadoxetate disodium injection followed by a single-dimensional post-exhale MRI (0.35-T MRI linear accelerator) and computed tomography simulation. The patient demographics and treatment-related outcomes were assessed. The time-to-event curves were analyzed for freedom from local progression (FFLP) and overall survival (OS). RESULTS: A total of 35 patients were eligible for analysis with a median age of 70 years (range 25 to 95). The median follow-up was 19.4 months (range 1 to 37 mo). The one-year OS was 77.7%, with an estimated 3 years of 47.9%. Patients with the locally controlled disease had a better median OS of 27.8 months (95% CI [23.8-31.6]) compared with 13.5 months (95% CI [5.6-21.3], P =0.007) in patients with local disease progression. The 1-year FFLP was 95.6%, and 3-year estimated FFLP was 87.1%. Patients who received a radiation dose of biologically equivalent dose≥100 Gy had FFLP of 30.9 months (95% CI [28.7-33.1]) compared with 13.3 months (95% CI [5.3-21.3], P =0.004) in patients who received <100 Gy biologically equivalent dose. CONCLUSION: MRI-guided SBRT provides optimal local control, associated with improved OS in a heavily morbid, pretreated older cohort of patients with reasonable safety profiles.

Quality assurance for nonradiographic radiotherapy localization and positioning systems: report of Task Group 147.

New technologies continue to be developed to improve the practice of radiation therapy. As several of these technologies have been implemented clinically, the Therapy Committee and the Quality Assurance and Outcomes Improvement Subcommittee of the American Association of Physicists in Medicine commissioned Task Group 147 to review the current nonradiographic technologies used for localization and tracking in radiotherapy. The specific charge of this task group was to make recommendations about the use of nonradiographic methods of localization, specifically; radiofrequency, infrared, laser, and video based patient localization and monitoring systems. The charge of this task group was to review the current use of these technologies and to write quality assurance guidelines for the use of these technologies in the clinical setting. Recommendations include testing of equipment for initial installation as well as ongoing quality assurance. As the equipment included in this task group continues to evolve, both in the type and sophistication of technology and in level of integration with treatment devices, some of the details of how one would conduct such testing will also continue to evolve. This task group, therefore, is focused on providing recommendations on the use of this equipment rather than on the equipment itself, and should be adaptable to each user's situation in helping develop a comprehensive quality assurance program.

Posterior lumbar spinal fusion and instrumentation in morbidly obese patients using the Synframe retractor system: technical note.

PURPOSE: Lumbar spine surgery in morbidly obese patients is a challenge to the operating surgeon. The aim of the study was to evaluate the surgical experience in this group of patients using the Synframe retractor system (Synthes, Paoli, PA, USA) as a tool for improved surgical access. METHODS: An Institutional Review Board approved retrospective study was conducted on 43 morbidly obese patients undergoing posterior lumbar decompression instrumentation and fusion. Patient selection was based on a BMI of >40. Information acquired included BMI, set up time, procedure time, ASA, intraoperative blood loss and the number of preoperative co-morbidities of each patient. Postoperative complications, length of stay, and pre-operative and postoperative Oswestry disability index (ODI) and visual analogue scale (VAS) were recorded at each postoperative visit. They were compared to 45 age matched controls from our spine database. RESULTS: The average set-up time (73.5 min), amount of blood loss (average 1,040 mL), length of incision (10.3-14.5 cm) and length of hospital stay (5.4 days) were recorded. The average surgical time was dependent on the procedure and number of levels fused and ranged from 164 to 245 min. These parameters were compared with normal weight patients and noted to be higher. CONCLUSION: The surgical experience determined that the Synframe retractor system provided a stable and well-illuminated operative field. It minimized the number of personnel required for assistance and improved surgical access. As may be expected, all the above recorded parameters were greater in the morbidly obese group.

Complications of anterior subcutaneous internal fixation for unstable pelvis fractures: a multicenter study.

BACKGROUND: Stabilization after a pelvic fracture can be accomplished with an anterior external fixator. These devices are uncomfortable for patients and are at risk for infection and loosening, especially in obese patients. As an alternative, we recently developed an anterior subcutaneous pelvic internal fixation technique (ASPIF). QUESTIONS/PURPOSES: We asked if the ASPIF (1) allows for definitive anterior pelvic stabilization of unstable pelvic injuries; (2) is well tolerated by patients for mobility and comfort; and (3) has an acceptable complication rate. METHODS: We retrospectively reviewed 91 patients who incurred an unstable pelvic injury treated with an anterior internal fixator and posterior fixation at four Level I trauma centers. We assessed (1) healing by callous formation on radiographs and the ability to weightbear comfortably; (2) patient function by their ability to sit, stand, lie on their sides, and how well they tolerated the implants; and (3) complications during the observation period. The minimum followup was 6 months (mean, 15 months; range, 6-40 months). RESULTS: All 91 patients were able to sit, stand, and lie on their sides. Injuries healed without loss of reduction in 89 of 91 patients. Complications included six early revisions resulting from technical error and three infections. Irritation of the lateral femoral cutaneous nerve was reported in 27 of 91 patients and resolved in all but one. Heterotopic ossification around the implants, which was asymptomatic in all cases, occurred in 32 of 91 patients. CONCLUSIONS: The anterior internal fixator provided high rates of union for the anterior injury in unstable pelvic fractures. Patients were able to sit, stand and ambulate without difficulty. Infections and aseptic loosening were reduced but heterotopic ossification and irritation of the LFCN are common. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Intraoperative radiation therapy for locally advanced and recurrent head and neck cancer.

The purpose of the present study was to present a single institution experience with intraoperative radiation therapy (IORT) for patients with head and neck cancer (HNC). The present study included all patients with HNC treated consecutively with IORT at Loyola University Medical Center between January 2014 and December 2018. Charts were reviewed for patient and tumor characteristics, IORT technical details, IORT-induced adverse events and treatment outcomes. The study included 23 eligible patients. Median patient age was 66 years (range, 34-91 years). Tumor sites included the parotid gland (43%), lymph nodes (43%), oral tongue (9%) and ear (4%). A total of 48% of patients received IORT upfront with or without postoperative adjuvant external beam radiation therapy (EBRT), whereas 52% received salvage IORT after local tumor recurrence. The median prescribed IORT dose was 7.5 Gy (range, 5-14 Gy) in a single fraction prescribed to 5 mm depth with flat applicators (median diameter, 5 cm). A total of 92% of patients did not experience wound healing complications. One patient (4%) developed postoperative acute thromboembolic stroke and a second patient (4%) experienced protracted wound healing. At a median follow up of 36 months (range, 2-81 months), overall survival was 52%. In addition, 48% of patients were reported to have no evidence of disease, and although two had died of unrelated causes, 13% of patients were alive with disease and 39% died with the disease. The local-regional recurrence rate was 39% (median time to local recurrence, 11 months; range, 1-34 months), the rate of distant metastasis was 35% (median time to distant metastasis, 16 months; range, 4-40 months), and 21% of patients had both local-regional recurrence and distant metastases. The percentages of local-regional recurrence and distant metastases among patients receiving salvage IORT were 58 and 50% respectively, compared with 18 and 18% respectively in those receiving upfront IORT with or without adjuvant EBRT. In the present single institution retrospective study, it was concluded that IORT for patients with locally advanced and recurrent HNC was a safe treatment modality, with tumor control comparable to historical IORT data. Larger prospective studies are needed to further assess the utility of IORT in the management of locally advanced and recurrent HNC.

Interventional nephrology and vascular access practice: A perspective from South and Southeast Asia.

South and Southeast Asia is the most populated, heterogeneous part of the world. The Association of Vascular Access and InTerventionAl Renal physicians (AVATAR Foundation), India, gathered trends on epidemiology and Interventional Nephrology (IN) for this region. The countries were divided as upper-middle- and higher-income countries as Group-1 and lower and lower-middle-income countries as Group-2. Forty-three percent and 70% patients in the Group 1 and 2 countries had unplanned hemodialysis (HD) initiation. Among the incident HD patients, the dominant Vascular Access (VA) was non-tunneled central catheter (non-TCC) in 70% of Group 2 and tunneled central catheter (TCC) in 32.5% in Group 1 countries. Arterio-Venous Fistula (AVF) in the incident HD patients was observed in 24.5% and 35% of patients in Group-2 and Group-1, respectively. Eight percent and 68.7% of the prevalent HD patients in Group-2 and Group-1 received HD through an AVF respectively. Nephrologists performing any IN procedure were 90% and 60% in Group-2 and Group 1, respectively. The common procedures performed by nephrologists include renal biopsy (93.3%), peritoneal dialysis (PD) catheter insertion (80%), TCC (66.7%) and non-TCC (100%). Constraints for IN include lack of time (73.3%), lack of back-up (40%), lack of training (73.3%), economic issues (33.3%), medico-legal problems (46.6%), no incentive (20%), other interests (46.6%) and institution not supportive (26%). Routine VA surveillance is performed in 12.5% and 83.3% of Group-2 and Group-1, respectively. To conclude, non-TCC and TCC are the most common vascular access in incident HD patients in Group-2 and Group-1, respectively. Lack of training, back-up support and economic constraints were main constraints for IN growth in Group-2 countries.

Radiographic and CT evaluation of recombinant human bone morphogenetic protein-2-assisted spinal interbody fusion.

OBJECTIVE: Bone morphogenetic proteins BMPs, when used in spinal fusion, hasten healing and initiate distinct imaging features. We undertook a study to record and analyze the radiographic and CT changes after the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in spinal fusion surgery. MATERIALS AND METHODS: This study included 95 patients who underwent spinal interbody fusion using rhBMP-2. The lumbar spine fusion cohort consisted of 23 patients who underwent anterior lumbar interbody fusion, 36 patients who underwent transforaminal lumbar interbody fusion, and two patients who underwent posterior lumbar interbody fusion. The remaining 34 patients underwent anterior cervical decompression and fusion. RESULTS: A polyetheretherketone cage was used as an interbody spacer in 59 patients (82 levels) and an allograft bone was the spacer in 36 patients (55 levels). Patients were evaluated 2 and 6 weeks after the procedure and then 3, 6, 12, and 24 months after the procedure. All patients underwent radiography at every follow-up visit, and CT evaluation was performed in 32 patients. CONCLUSION: Features observed on imaging that we attributed to the use of rhBMP-2 included an enhanced fusion rate and an increased incidence of prevertebral soft-tissue swelling in patients who underwent cervical fusion. Endplate resorption was observed in 100% of patients who underwent cervical fusion and in 82% of the lumbar levels. Subsidence of the cage resulting in narrowing of the disk space was seen in more than 50% of cases. Cage migration and heterotopic bone formation in the spinal canal and neural foramen occurred maximally in the lumbar spine of patients in whom a polyetheretherketone cage was placed using a transforaminal approach.

Patterns of mouthguard utilization among atom and pee wee minor ice hockey players: a pilot study.

OBJECTIVE: To determine if youth hockey players wear their mouthguards properly, and if not, why? DESIGN: Descriptive cross-sectional study. SETTING: Tecumseh Shoreline Minor Hockey Association, Tecumseh, Ontario, Canada, during the 2007-2008 season. PARTICIPANTS: Subjects were 180 travel hockey players of the Tecumseh Shoreline Minor Hockey Association at the Atom or Pee Wee level (aged 9-12 y) or their competitors. ASSESSMENT OF RISK FACTORS: Players were asked to complete a survey addressing mouthguard wear under their coach's supervision. MAIN OUTCOME MEASURES: The type of mouthguard, whether mouthguards were worn at all and worn properly, and the reasons for noncompliance. The incidence of concussion and association to mouthguard-wearing tendencies were also assessed. RESULTS: Sixty-eight percent [95% confidence interval (CI), 60.4%-74.5%] of subjects always wore their mouthguards, but only 31.7% (95% CI, 25.0%-39.0%) wore them properly during games and 51.1% (95% CI, 43.6%-58.6%) during practice. Custom-made mouthguards were most likely to be worn properly, followed by boil-and-bite and stock-type guards. Younger players wore mouthguards more consistently than older players (P < 0.01). Reasons for not wearing the guard included the following: 43.0% (95% CI, 35.4%-50.4%) of subjects felt it made talking difficult, 27.4% (95% CI, 20.9%-34.3%) felt it uncomfortable, 23.9% (95% CI, 17.9%-30.8%) felt it made breathing difficult, and 12.4% (95% CI, 8.3%-17.9%) thought it did not fit correctly. The incidence of concussion was 17.8%, but the study was underpowered for any association with mouthguard type. CONCLUSIONS: Even when mouthguards are mandated to be worn in a children's travel hockey league, young players self-report that they routinely fail to wear them properly.

Pedicle screw fixation of the C7 vertebra using an anteroposterior fluoroscopic imaging technique.

Cervical pedicle screws have been reported to be biomechanically superior to lateral mass screws. However, placement of these implants is a technical challenge. The purpose of this investigation was to use an anatomic and a clinical study to evaluate a technique for placement of the pedicle screws in the C7 vertebra using fluoroscopic imaging in only the anteroposterior (A/P) plane. Ten adult cadaver C7 vertebrae were used to record the pedicle width, inclination and a suitable entry point for placement of pedicle screws. A prospective study of 28 patients undergoing posterior instrumentation of the cervical spine with C7 pedicle screw placement was also performed. A total of 55 C7 pedicle screws were placed using imaging only in the A/P plane with screw trajectory values obtained by the anatomic study. Radiographs and CT scans were performed post-operatively. The average posterior pedicle diameter of C7 vertebra was 9.5 ± 1.2 mm in this study. The average middle pedicle diameter was 7.1 mm and the average anterior pedicle diameter was 9.2 mm. The average transverse pedicle angle was 26.8 on the right and 27.3 on the left. CT scans were obtained on 20 of 28 patients which showed two asymptomatic cortical wall perforations. One screw penetrated the lateral wall of the pedicle and another displayed an anterior vertebral penetration. There were no medial wall perforations. The preliminary results suggest that this technique is safe and suitable for pedicle screw placement in the C7 vertebra.

On-Treatment Verification Imaging.

The integration of on-board imaging (OBI) with linear accelerators paved the way for Image Guided Radiation Therapy (IGRT) as it is practiced today in the clinic. The advent of IGRT is a major milestone in the history of radiotherapy. The main goal of image guidance in radiotherapy is to improve radiation treatment delivery via superior localization and tracking of target cancer cells. IGRT is hence integral to accurate, precise and safe delivery of radiotherapy.

Dosimetric feasibility of brain stereotactic radiosurgery with a 0.35 T MRI-guided linac and comparison vs a C-arm-mounted linac.

PURPOSE: MRI is the gold-standard imaging modality for brain tumor diagnosis and delineation. The purpose of this work was to investigate the feasibility of performing brain stereotactic radiosurgery (SRS) with a 0.35 T MRI-guided linear accelerator (MRL) equipped with a double-focused multileaf collimator (MLC). Dosimetric comparisons were made vs a conventional C-arm-mounted linac with a high-definition MLC. METHODS: The quality of MRL single-isocenter brain SRS treatment plans was evaluated as a function of target size for a series of spherical targets with diameters from 0.6 cm to 2.5 cm in an anthropomorphic head phantom and six brain metastases (max linear dimension = 0.7-1.9 cm) previously treated at our clinic on a conventional linac. Each target was prescribed 20 Gy to 99% of the target volume. Step-and-shoot IMRT plans were generated for the MRL using 11 static coplanar beams equally spaced over 360° about an isocenter placed at the center of the target. Couch and collimator angles are fixed for the MRL. Two MRL planning strategies (VR1 and VR2) were investigated. VR1 minimized the 12 Gy isodose volume while constraining the maximum point dose to be within ±1 Gy of 25 Gy which corresponded to normalization to an 80% isodose volume. VR2 minimized the 12 Gy isodose volume without the maximum dose constraint. For the conventional linac, the TB1 method followed the same strategy as VR1 while TB2 used five noncoplanar dynamic conformal arcs. Plan quality was evaluated in terms of conformity index (CI), conformity/gradient index (CGI), homogeneity index (HI), and volume of normal brain receiving ≥12 Gy (V12Gy ). Quality assurance measurements were performed with Gafchromic EBT-XD film following an absolute dose calibration protocol. RESULTS: For the phantom study, the CI of MRL plans was not significantly different compared to a conventional linac (P > 0.05). The use of dynamic conformal arcs and noncoplanar beams with a conventional linac spared significantly more normal brain (P = 0.027) and maximized the CGI, as expected. The mean CGI was 95.9 ± 4.5 for TB2 vs 86.6 ± 3.7 (VR1), 88.2 ± 4.8 (VR2), and 88.5 ± 5.9 (TB1). Each method satisfied a normal brain V12Gy  ≤ 10.0 cm3 planning goal for targets with diameter ≤2.25 cm. The mean V12Gy was 3.1 cm3 for TB2 vs 5.5 cm3 , 5.0 cm3 and 4.3 cm3 , for VR1, VR2, and TB1, respectively. For a 2.5-cm diameter target, only TB2 met the V12Gy planning objective. The MRL clinical brain plans were deemed acceptable for patient treatment. The normal brain V12Gy was ≤6.0 cm3 for all clinical targets (maximum target volume = 3.51 cm3 ). CI and CGI ranged from 1.12-1.65 and 81.2-88.3, respectively. Gamma analysis pass rates (3%/1mm criteria) exceeded 97.6% for six clinical targets planned and delivered on the MRL. The mean measured vs computed absolute dose difference was -0.1%. CONCLUSIONS: The MRL system can produce clinically acceptable brain SRS plans for spherical lesions with diameter ≤2.25 cm. Large lesions (>2.25 cm) should be treated with a linac capable of delivering noncoplanar beams.

Transforaminal lumbar interbody fusion using unilateral pedicle screws and a translaminar screw.

Lumbar spinal fusion is advancing with minimally invasive techniques, bone graft alternatives, and new implants. This has resulted in significant reductions of operative time, duration of hospitalization, and higher success in fusion rates. However, costs have increased as many new technologies are expensive. This study was carried out to investigate the clinical outcomes and fusion rates of a low implant load construct of unilateral pedicle screws and a translaminar screw in transforaminal lumbar interbody fusion (TLIF) which reduced the cost of the posterior implants by almost 50%. Nineteen consecutive patients who underwent single level TLIF with this construct were included in the study. Sixteen patients had a TLIF allograft interbody spacer placed, while in three a polyetheretherketone (PEEK) cage was used. Follow-up ranged from 15 to 54 months with a mean of 32 months. A clinical and radiographic evaluation was carried out preoperatively and at multiple time points following surgery. An overall improvement in Oswestry scores and visual analogue scales for leg and back pain (VAS) was observed. Three patients underwent revision surgery due to recurrence of back pain. All patients showed radiographic evidence of fusion from 9 to 26 months (mean 19) following surgery. This study suggests that unilateral pedicle screws and a contralateral translaminar screw are a cheaper and viable option for single level lumbar fusion.

Hip dislocation after modular unipolar hemiarthroplasty.

An institutional review board-approved retrospective review of hip fractures in elderly patients treated with a modular unipolar implant was carried out to identify factors predisposing to dislocation of a hemiarthroplasty. The main outcome measure evaluated was dislocation vs nondislocation. Two hundred seventeen patients underwent the surgery, and 174 were available for review at 6 weeks and 144 at 1 year. The incidence of dislocation was 6%. The average time of dislocation after surgery was 19.3 days. Clinical factors significant for dislocation were male sex and mental disease. Radiographic factors in dislocated hips included a smaller femoral neck and contralateral femoral neck offset. The center edge angle was also smaller in the dislocated patients. These patients had a higher mortality rate.

Complications in the use of rhBMP-2 in PEEK cages for interbody spinal fusions.

STUDY DESIGN: All patients of spinal interbody fusion using polyetheretherketone (PEEK) cages and recombinant human bone morphogenetic protein (rhBMP)-2 performed over a 16-month period were reviewed. OBJECTIVE: To determine the suitability of PEEK cages when used in conjunction with rhBMP-2 in interbody spinal fusion. SUMMARY OF BACKGROUND DATA: Bone morphogenetic proteins are increasingly being used in spinal fusion to promote osteogenesis. PEEK is a semicrystalline aromatic polymer that is used as a structural spacer to maintain the disc and foraminal height. Their use has led to increased and predictable rates of fusion. However, not many reports of the adverse effects of their use are available. METHODS: Fifty-nine consecutive patients of interbody spinal fusion in the cervical or lumbar spine using a PEEK cage and rhBMP-2 were followed for an average of 26 months after surgery. A clinical examination and a record of Oswestry Disability Index, Visual Analog Scale for pain, and a pain diagram were performed preoperatively and at every follow-up visit. All patients had plain radiographs carried out to assess fusion. Ten patients of lumbar spine fusion were additionally evaluated with a computed tomography scan. RESULTS: All cases demonstrated an appreciable amount of new bone formation by 6 to 9 months in the cervical spine and by 9 to 12 months in the lumbar spine. End plate resorption was visible radiologically in all cervical spine fusions and majority of lumbar fusions. Cage migration was observed to occur maximally in patients with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. Disc space subsidence was seen in both cervical and lumbar arthrodesis with the latter showing a lesser incidence, but with a greater degree of collapse. CONCLUSIONS: PEEK cages and rhBMP-2 when used in spinal fusion give consistently good fusion rates. However, the early role of BMP in the resorptive phase may cause loosening, cage migration, and subsidence.

Intraoperative Radiotherapy With INTRABEAM: Technical and Dosimetric Considerations.

PURPOSE: We evaluate dose characteristics and clinical applications of treatment accessories used in intraoperative radiotherapy (IORT) and make site-specific recommendations for their optimal use. METHODS AND MATERIALS: Dose measurements were performed for a low energy (50 kV) X-ray INTRABEAM source. For spherical, flat, surface, and needle applicators, the following dosimetric parameters were measured: depth-dose (DD) profiles, surface dose (Ds), output factors (OF), and target dose homogeneity (DH). Optical density versus exposure calibration films were employed to obtain 2-dimensional dose distributions in planes parallel and perpendicular to beam direction. Film results were verified via repeat dose measurements with a parallel-plate ionization chamber in a custom water tank. The impact of applicator design on dose distributions was evaluated. RESULTS: Spherical applicators are commonly used for treating the inner-surface of breast lumpectomy cavity. Flat and surface applicators provide uniform planar dose for head and neck, abdomen, and pelvis targets. Needle applicators are designed for kypho-IORT of spinal metastasis. Typically, larger applicators produce a more homogeneous target dose region with lower surface dose, but require longer treatment times. For 4-cm diameter spherical, flat, and surface applicators, dose rates (DR) at their respective prescription points were found to be: 0.8, 0.3, and 2.2 Gy/min, respectively. The DR for a needle applicator was 7.04 Gy/min at 5 mm distance from the applicator surface. Overall, film results were in excellent agreement with ion-chamber data. CONCLUSION: IORT may be delivered with a variety of site-specific applicators. Appropriate applicator use is paramount for safe, effective, and efficient IORT delivery. Results of this study should help clinicians assure optimized target dose coverage and reduced normal tissue exposure.