Peter Thomsen

Introduction : Mobility restriction following limb loss might lead to a sedentary lifestyle, impacting health. Daily activity monitoring of amputees has focused on prosthetic steps, neglecting overall activity. Purpose : To assess daily activity in individuals with an established amputation and to explore the amount of activity recorded from the prosthesis as compared to the overall activity. Methods : Individuals with a unilateral transfemoral amputation or knee disarticulation who had used a prosthesis in daily life for >1 year and could walk 100 m (unsupported or single aided) were recruited. Descriptive information and prosthetic mobility were collected. Two activPAL™ accelerometers were attached to the nonamputated thigh and the prosthesis, respectively. The mean daily activity over 7 days was compared between the nonamputated limb and the prosthesis. Results : Thirty-nine participants (22 men/17 women; mean age 54 [14.5] years) with amputation mainly due to trauma (59%) or tumor (28%) were included. Overall, participants took 6,125 steps and spent 10.2 hr sedentary, 5.0 hr upright, and 8.7 hr laying per day. Compared to recordings from the nonamputated limb, 85% of sit-to-stand transitions (32/38), 73% of steps (4,449/6,125), and 68% of walking time (1.0/1.5 hr) were recorded from the prosthesis. Recordings seemed to be less adequate for incidental prosthetic steps than for walks. Conclusions : Sedentary behavior accounted for most of the day demonstrating the importance to encourage physical activity among established prosthetic users. The prosthesis is used for daily activity to a great extent. However, noted pitfalls in the recordings call for further refinement of the measurements.

Background Nonresorbable membranes promote bone formation during guided bone regeneration (GBR), yet the relationships between membrane properties and molecular changes in the surrounding tissue are largely unknown. Aim To compare the molecular events in the overlying soft tissue, the membrane, and the underlying bone defect during GBR using dual‐layered expanded membranes versus dense polytetrafluoroethylene (PTFE) membranes. Materials and Methods Rat femur defects were treated with either dense PTFE (d‐PTFE) or dual‐layered expanded PTFE (dual e‐PTFE) or left untreated as a sham. Samples were collected after 6 and 28 days for gene expression, histology, and histomorphometry analyses. Results The two membranes promoted the overall bone formation compared to sham. Defects treated with dual e‐PTFE exhibited a significantly higher proportion of new bone in the top central region after 28 days. Compared to that in the sham, the soft tissue in the dual e‐PTFE group showed 2‐fold higher expression of genes related to regeneration (FGF‐2 and FOXO1) and vascularization (VEGF). Furthermore, compared to cells in the d‐PTFE group, cells in the dual e‐PTFE showed 2.5‐fold higher expression of genes related to osteogenic differentiation (BMP‐2), regeneration (FGF‐2 and COL1A1), and vascularization (VEGF), in parallel with lower expression of proinflammatory cytokines (IL‐6 and TNF‐α). Multiple correlations were found between the molecular activities in membrane‐adherent cells and those in the soft tissue. Conclusion Selective surface modification of the two sides of the e‐PTFE membrane constitutes a novel means of modulating the tissue response and promoting bone regeneration.