Long-term effect of intrathecal baclofen treatment on bone health and body composition after spinal cord injury:A case matched report

BACKGROUND Severe spasticity may negatively impact functionality and quality of life after spinal cord injury(SCI).Intrathecal baclofen treatment(IBT)is effectively used to manage severe spasticity and reduce comorbidities.However,long-term IBT may have a negative effect on bone mineral content(BMC),bone mineral density(BMD)and body composition(such as percentage fat mass and lean body mass).We demonstrated the negative effects of long-term IBT use in a single case compared with two non-IBT users.CASE SUMMARY A 46-year old Caucasian male Veteran(case)with a 21 year history of complete tetraplegia(complete C6 SCI)was implanted with IBT for 20 years.The case was matched to two participants with different time since injuries[2(match 1)and 13(match 2)years]without IBT.Knee BMC and BMD at the epiphysis and metaphysis of the distal femur and proximal tibia were evaluated using dual knee and the dual femur modules of GE Lunar iDXA software.Total and leg body composition assessments were also conducted for the three participants.Potential effect of long-term IBT was demonstrated by changes in BMD,consistent with bone demineralization,at the distal femur and proximal tibia and changes in percentage fat mass and lean mass of legs.The case showed 113%lower BMD at the distal femur,and 78.1%lower at the proximal tibia compared to match 1,moreover the case showed 45%lower BMD at the distal femur,and no observed changes at the proximal tibia compared to match 2.The case had 27.1%and 16.5%greater leg%fat mass compared to match 1 and match 2,respectively.Furthermore,the case had 17.4%and 11.8%lower%leg lean mass compared to match 1 and match 2,respectively.CONCLUSION Long-term IBT may impact bone health and body composition parameters in persons with complete SCI.It may be prudent to encourage regular screening of individuals on long-term IBT considering the prevalence of osteoporosis related fractures,cardiovascular diseases,and metabolic disorders in this population.

A new experimental model to study healing process of metaphyseal fracture

Background There are few researches for the healing of metaphyseal fractures; moreover,the animal models to study the metaphyseal fractures are usually made by the oscillating saw osteotomy without reliable fixation,which is not in accordance with our current clinical practice.In this study,we established a new model to observe the healing process of metaphyseal fractures.Methods Eighteen New Zealand rabbits were used in the study.The fracture model was created by splitting the medial tibial plateau in rabbits,then reset,and fixed with compression screws.At 1,2,3,4,6,and 8 weeks postoperatively,the tibial specimens were collected; firstly,a general observation and an X-ray examination of the specimens was done,and then they were embedded in methylmethacrylate and cut into sections with hard tissue slicer.The sections were stained with Giemsa reagent and examined under light microscopy.Results There was no fracture displacement in the tibial specimens of all time points,except for one showing a collapse.No external callus formation could be observed by X-ray and general examination.After 1 week of the operation,the fracture gap was filled by mesenchymal tissue; 2 weeks postoperatively,a large number of woven bones were formed; from the third week onwards,the woven bone began to turn into lamellar bone,and new trabecular structure began to form.In all of the slices,no obvious chondrocytes formed in fracture areas; thus,there was no endochondral ossification.Conclusions This model was an ideal fracture animal model and suitable for the study of metaphyseal fracture healing.The X-ray and histological images demonstrated that metaphyseal fracture healing was a process of direct bone healing through intramembranous bone formation under the conditions of minor trauma,good reduction,and firm fixation.

Whole body vibration with rest days could improve bone quality of distal femoral metaphysis by regulating trabecular arrangement

Low-magnitude, high-frequency vibration(LMHFV) with rest days(particularly seven rest days) was considerably effective in improving the morphological and mechanical properties of rat proximal femur. However, current knowledge is limited regarding the possible benefit of this mechanical regimen to other bone sites and whether the optimal rest days are the same. This study followed our previous experiment on LMHFV loading with rest days for three-month-old male Wistar rats. The experiment involved seven groups, namely, vibrational loading for X day followed with X day rest(X=1, 3, 5, 7), daily vibrational loading,tail suspension and baseline control. Micro-computed tomography(micro-CT) scanning was used to evaluate the microarchitecture of the distal femoral trabecular bone. Micro-CT image-based microfinite element analysis was performed for each distal femoral metaphysis. LMHFV with rest days substantially changed the trabecular arrangement from remarkably plate-like to rod-like. Vibrational loading with 1 day rest was substantially effective in improving the architecture and apparent-and tissuelevel mechanical properties of the rat distal femoral metaphysis. This study may provide an improved understanding of the sitespecific responses of bone tissue to LMHFV with rest days for a substantially effective therapy of a targeted bone site.