T2-relaxation time increases in lumbar intervertebral discs after 21d head-down tilt bed-rest.

OBJECTIVES: Spaceflight back pain and intervertebral disc (IVD) herniations cause problems in astronauts. Purpose of this study was to assess changes in T2-relaxation-time through MRI measurements before and after head-down tilt bed-rest, a spaceflight analog. METHODS: 8 men participated in the bed-rest study. Subjects remained in 6° head down tilt bed-rest in two campaigns of 21 days, and received a nutritional intervention (potassium bicarbonate 90 mmol/d) in a cross-over design. MRI measurements were performed 2 days before bed-rest, as well as one and five days after getting up. Image segmentation and data analysis were conducted for the IVDs Th12/L1 to L5/S1. RESULTS: 7 subjects, average age of 27.6 (SD 3.3) years, completed the study. Results showed a significant increase in T2-time in all IVDs (p⟨0.001), more pronounced in the nucleus pulposus than in the annulus fibrosus (p⟨0.001). Oral potassium bicarbonate did not show an effect (p=0.443). Pfirrmann-grade correlated with the T2-time (p⟨0.001). CONCLUSIONS: 6° head-down tilt bed-rest leads to a T2-time increase in lumbar IVDs. Oral potassium bicarbonate supplementation does not have an effect on IVD T2-time.

A novel classification of screw placement accuracy in the cervical spine.

BACKGROUND: Goal of this study is to present an easily reproducible and reliable measurement to evaluate accuracy of screw placement in cervical spine. METHODS: Accuracy of cervical screw position was assessed in 52 patients treated with 163 screws. Each patient receiving pedicle, transarticular C1/2, lateral mass, or laminar screws and postoperative CT scan was included. Placement position was categorized in 5 grades: Grade 1 is ideal with pedicle wall perforation < 1 mm, grade 2 < 2 mm, grade 3 < 3 mm, and grade 4 < 4 mm. Grade 5 > 4 mm and/or obstruction of transverse foramen by more than half a screw diameter. Intraclass correlation coefficient (ICC) values were assessed for inter- and intraobserver reliability. RESULTS: The mode of individual evaluations was calculated to assign a single value to each screw. This yielded 89 grade 1 (54.6%), 48 grade 2 (29.4%), 14 grade 3 (8.6%), 3 grade 4 (1.8%), and 9 grade 5 (5.5%) screws. Intraobserver reliability ICC was 0.966 and 0.959 for measurements. Interobserver reliability ICC was 0.938. CONCLUSION: This study introduces a reliable classification of cervical spine instrumentation with various screw types. This should enable the use of a uniform and reproducible, and thus comparable classification for screw position in cervical spine.

The accuracy of 3D fluoroscopy-navigated screw insertion in the upper and subaxial cervical spine.

PURPOSE: Due to better primary stability and repositioning options, pedicle screws are increasingly used during posterior stabilization of the cervical spine. However, the serious risks generally associated with the insertion of screws in the cervical spine remain. The purpose of this study is to examine the accuracy of pedicle screw insertion with the use of 3D fluoroscopy navigation systems, also accounting for various spine levels. METHODS: Data of 64 patients were collected during and after screw implantation (axial and subaxial) in the cervical spine. 207 screws were implanted from C1 to C7 and analyzed for placement accuracy according to postoperative CT scans and following the modified Gertzbein and Robbins classification. RESULTS: The accuracy of most of the inserted screws was assessed as grade 2 according to the modified Gertzbein and Robbins classification. 93.9% of the screws implanted at C1 or C2, and 78.51% of the screws implanted at levels C3-C7 showed placement accuracy grade 2 or better, indicating pedicle wall perforation of <2 mm. Overall, seven complications were observed. In three cases, the vertebral artery was affected, leading to one fatality. Surgical revision was necessary once because of Magerl screw misplacement and three times due to impaired wound healing. No radicular symptoms resulted from screw malposition. CONCLUSION: Axial and subaxial screws can be inserted with a high grade of accuracy using 3D fluoroscopy-based navigation systems. Nevertheless, while this useful innovation helps to minimize the risks of misplacement, the surgery is still a challenge, as arising complications remain severe.

Hypervascular cervical spine metastases: embolization by direct injection of Onyx-18.

PURPOSE: Spinal metastases are common in patients with cancer. Following lung and liver, spine is the most common site for cancers to metastasize. Many of them are hypervascularized. These cases are a particular challenge for the surgeon and represent a significant danger of massive blood loss during surgery. Hypervascularized metastases of the cervical spine also include the risk of postoperative bleeding with severe neurological impairment. We report a case of a 67-year-old women with breast cancer (BC) metastasis within the vertebral bodies of C3 and C4 with nearly complete bony destruction of the ventral column and intraspinal tumor masses compressing the spinal cord at level C3 and C4. The hypervascularized tumor was supplied by multiple minor vessels from both vertebral arteries, too small to be coiled individually. Due to an allergy to aspirin, intravascular stenting of the vertebral arteries was not an option. We decided to perform a preoperative direct injection of onyx-18 for embolization of the tumor. CONCLUSION: Presurgical direct injection of Onyx-18 for treating hypervascular spinal metastases of breast cancer seems to be an effective and safe technique and reduces intraoperative bleeding to a minimum.

In vivo measurements of human bone deformation using optical segment tracking: surgical approach and validation in a three-point bending test.

The purpose of the study was to validate optical segment tracking, a new method for in vivo human tibia deformation measurements and to assess bending in a three-point bending test. The approach relies upon optical motion capturing of reflecting marker clusters affixed to the bone via screws inserted three millimeters into the corticalis in local anesthesia. The method was tested in five healthy subjects. Screws were left in place for six to eight hours and a variety of exercises performed. A pain questionnaire was used to assess pain levels. PQCT-images were taken to locate screw holes in the bone. A three-point bending test was performed and repeatability evaluated. The new method shows good feasibility though this was previously considered impossible by many experts. Local anesthesia works for screw implantation and explantation. Results show linearity with an average of 0.25 degrees per 10 kg of weight applied with good repeatability (average variation coefficient 8%). Optical segment tracking is feasible for human in vivo bone deformation measurements. There is a variety of possible clinical and experimental applications including stability testing of osteosyntheses and joints, monitoring of bone healing, evaluation of exercises in physiotherapy, and assessment of bone deformation patterns in bone disease.

[Complication analysis of spinal interventions in adult central movement disorders and scoliosis]. / Komplikationsanalyse von spinalen Eingriffen bei adulten zentralen Bewegungsstörungen und Skoliosen.

BACKGROUND: Adult central movement disorders, malpostures, and scolioses can have their cause in various neurological underlying diseases such as Morbus Parkinson, Pisa syndrome, or segmental dystonia. Important clinical characteristics are marked postural distortions such as camptocormia (bent spine) or laterocollis. In cases of these adult scolioses, surgical spine treatment puts high demands on the surgeon. Surgery in Parkinson's disease, for example, is associated with serious surgery-specific as well as general complications. The more rarely occurring Pisa syndrome is an entity primarily requiring medical therapy. PATIENTS AND METHODS: A series of ten case reports of patients with Morbus Parkinson and Pisa syndrome who underwent spinal surgery is presented and discussed. From these reports, treatment recommendations have been derived and complemented by references from the literature. An extensive MEDLINE search was performed for this purpose. RESULTS AND CONCLUSION: In patients suffering from Parkinson's disease, even minor surgical interventions can lead to instability of whole spine segments or even the entire spine. Implant loosening, adjacent segment instability, general perioperative complications, and progressive malposture due to disease progress can bring forth disastrous treatment courses. Spinal fixation should be performed long-segmented in combination with ventral stabilisation. Due to osteoporosis, pedicle screw cement augmentation is recommended in this collective. If the diagnosis of Pisa syndrome is established, an optimised preoperative preparation should be initiated in close cooperation with neurologists. In many cases medical therapy is sufficient and surgical interventions can be avoided.

Clinical outcomes and quality of life 1 year after open microsurgical decompression or implantation of an interspinous stand-alone spacer.

BACKGROUND: Interspinous stand-alone implants are inserted without open decompression to treat symptomatic lumbar spinal stenosis (LSS). The insertion procedure is technically simple, low-risk, and quick. However, the question remains whether the resulting clinical outcomes compare with those of microsurgical decompression, the gold standard. MATERIAL AND METHODS: This prospective, comparative study included all patients (n=36) with neurogenic intermittent claudication (NIC) secondary to LSS with symptoms improving in forward flexion treated operatively with either interspinous stand-alone spacer insertion (Aperius (®); Medtronic, Tolochenaz, Switzerland) (group 1) or microsurgical bilateral operative decompression (group 2) between February 2007 and November 2008. Data (patient data, operative data, COMI, SF-36 PCS and MCS, ODI, and walking tolerance) were collected preoperatively as well as at 6 weeks, at 3, 6, and 9 months, and at one year follow-up (FU). All patients had complete FU over 1 year. RESULTS: Compared to preoperative measurements, surgery led to improvements of all parameters in the entire collective as well as both individual groups. There were no statistically relevant differences between the 2 groups over the entire course of FU. However, improvements in the ODI and SF-36 MCS were not significant in group 1, in contrast to those of group 2. Also, although in group 1 the improvements in leg pain (VAS leg) were still significant (p<0.05) at 6 months, this was no longer the case at 1 year FU. In group 1 at 1 year FU an increase in leg pain was observed, while in group 2, minimal improvements continued. Walking tolerance was significantly improved at all FU times compared to preoperatively, regardless of group (p<0.01). At no time there was a significant difference between the groups. In group 1, admission and operative times were shorter and blood loss decreased. The complication rate was 0% in group 1 and 20% in group 2, however reoperation was required by 27.3% of group 1 patients and 0% of group 2. CONCLUSION: Implantation of an interspinous stand-alone spacer yields clinical success comparable to open decompression, at least within the first year of FU. The 1-year conversion rate of 27.3% is, however, decidedly too high.

[Effects of hospital and surgeon procedure volume on outcome in total hip replacement]. / Einfluss von Mindestmengen auf die Ergebnisqualität in der Hüftendoprothetik.

AIM: According to the "practice makes perfect" hypothesis, the mortality rates of many surgical procedures are inversely related to hospital and surgeon procedure volume. Currently there is a discussion regarding the implementation of high-volume centres for total hip replacement. Nevertheless, the body of evidence describing such an association is weak. Therefore the American National Cancer Policy Board came up with four evidence criteria describing a valid association between volume and outcome: 1) the association must be logical, 2) the association must be consistent in all studies, 3) the size of the measured effect must be substantial and clinically relevant and 4) the effect has to be reproducible in clinical studies. METHOD: We searched MEDLINE and EMBASE (1996 until November 2006) using the following "medical subject headings" (MeSH): "Arthroplasty, Replacement, Hip" or "Hip Prosthesis" and "Volume". We searched for full articles that reported on an association between hospital and surgeon procedure volume and outcome after total hip replacement. No language restriction was applied. RESULTS: We found 17 relevant studies in MEDLINE and EMBASE. The outcome after primary hip prosthesis and revision hip prosthesis was better when performed in high-volume hospitals or by high-volume surgeons. Depending on the cut-off for the definition of "high volume" and "low volume" the results could be statistically significant. CONCLUSION: Many of the included studies were of minor quality, the data were often not comparable between studies. Therefore, the results are not directly transferable to our medical system in Germany. Applying the criteria designed by the American National Cancer Policy Board on the studies about procedure volume and outcome after total hip replacement yields the following result: 1) the association must be logical: Yes. 2) The association must be consistent in all studies: Yes. 3) The size of the measured effect must be substantial and clinically relevant and has to be analysed using validated statistical criteria: No. 4) The effect has to be reproducible in clinical studies: No.

[Intradiscal electrothermal therapy (IDET)]. / Intradiskale elektrothermale Therapie (IDET).

Low back pain is a major physical and socioeconomic problem. A significant percentage is attributable to internal disc disruption (IDD). The management of IDD has been limited to conservative treatment or to operative treatment. Intradiscal electrothermal therapy (IDET) is a new minimal-invasive therapy. In carefully selected patients, it could be an effective treatment alternative. Further studies with long-term follow-up are necessary.