Changes in lower extremity joint moments one-year following osseointegration in individuals with Transfemoral lower-limb amputation: A case series.

BACKGROUND: Dissatisfaction with socket prostheses has led to the development of bone-anchored prostheses through osseointegration for people with transfemoral amputation, eliminating the need for a prosthetic socket. Gait deviations of transfemoral prosthesis users may be linked to increased risk of osteoarthritis, and it remains unknown if gait biomechanics change following osseointegration. The purpose of this case series was to evaluate the longitudinal changes in joint kinetics one year post-osseointegration in patients with transfemoral amputation during walking. METHODS: Knee, hip, and trunk internal moments were evaluated in the prosthetic and intact limbs during walking at a self-selected speed in four participants pre- and one-year post-osseointegration. Longitudinal changes were quantified using the percent change (%∆) in peak joint moments between the two time points and Cohen's d (d) effect size was used to determine the magnitude of effect on joint moments during walking one year following osseointegration. FINDINGS: Participants demonstrated increased peak knee extension moment (224 ± 308%∆, d = -1.31) in the prosthetic limb, while demonstrating reduced peak knee extension moment (-43 ± 34%∆, d = 1.82) in the intact limb post-osseointegration. Participants demonstrated bilateral reduction of peak hip extension moment (prosthetic: -22 ± 37%∆, d = 0.86; intact: -29 ± 10%∆, d = 1.27) and bilateral increase of peak hip abduction moment (prosthetic: 45 ± 40%∆, d = 1.20; intact: 23 ± 44%∆, d = 0.74) post-osseointegration. Participants demonstrated reduced peak trunk moments on both the prosthetic (extension: -31 ± 16%∆, d = 1.51; lateral flexion: -21 ± 20%∆, d = 0.63) and intact side (extension: -7 ± 22%∆, d = 0.38; lateral flexion: -22 ± 18%∆, d = 1.12) post-osseointegration. INTERPRETATION: This case series suggests improved gait symmetry in individuals with transfemoral amputation one year following osseointegration, justifying future investigation.

Predicting Division Planes of Three-Dimensional Cells by Soap-Film Minimization.

One key aspect of cell division in multicellular organisms is the orientation of the division plane. Proper division plane establishment contributes to normal plant body organization. To determine the importance of cell geometry in division plane orientation, we designed a three-dimensional probabilistic mathematical model to directly test the century-old hypothesis that cell divisions mimic soap-film minima. According to this hypothesis, daughter cells have equal volume and the division plane occurs where the surface area is at a minimum. We compared predicted division planes to a plant microtubule array that marks the division site, the preprophase band (PPB). PPB location typically matched one of the predicted divisions. Predicted divisions offset from the PPB occurred when a neighboring cell wall or PPB was directly adjacent to the predicted division site to avoid creating a potentially structurally unfavorable four-way junction. By comparing divisions of differently shaped plant cells (maize [Zea mays] epidermal cells and developing ligule cells and Arabidopsis thaliana guard cells) and animal cells (Caenorhabditis elegans embryonic cells) to divisions simulated in silico, we demonstrate the generality of this model to accurately predict in vivo division. This powerful model can be used to separate the contribution of geometry from mechanical stresses or developmental regulation in predicting division plane orientation.

Abdominal wall hernia repair: a long-term comparison of Sepramesh and Dualmesh in a rabbit hernia model.

Surgeons are faced with a wide variety of mesh products, which they can use to perform tension-free abdominal wall hernia repair. The purpose of this study is to compare Sepramesh (SM) and Dualmesh (DM) in terms of strength of tissue incorporation, mesh shrinkage, and adhesiogenesis. We conducted a prospective, randomized trial using 24 New Zealand White rabbits. Each animal underwent creation of a standardized ventral hernia defect and was randomized to receive either SM or DM repair. There were 12 animals in each study arm. Five months postoperatively, the animals were sacrificed and the hernia repairs were analyzed. Specimens were evaluated for strength of incorporation (SOI), mesh shrinkage, as well as the type and amount of adhesions. SOI for DM was not statistically different from SM (37.2N vs 40.8N). DM underwent significantly more shrinkage than did SM (50.8% vs 32.6%, P < 0.0001). Adhesions were predominantly omental in nature. DM demonstrated a greater amount of adhesed area as a percentage of the mesh (30.7% vs 25.2%), but fewer adhesions in terms of absolute area involved (636 mm2 vs 717 mm2). This difference was not statistically significant. Previous studies, terminated at 30 days, demonstrated an increased SOI for SM as compared to DM. This study shows that SOI for DM continues to increase over time such that it is equivalent to DM at 5 months. Though there is increased mesh shrinkage for DM, adhesions to the two materials are equivalent.