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.

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]

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]

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)]

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.