When conducting extravehicular activities under low-gravity conditions like on the moon,the weight of the spacesuit is one of the loads that human body has to bear.The centroid position of the spacesuit will affect the motion control of the human-spacesuit system.In order to reveal the influence of the centroid position of the lunar spacesuit on human motion under lunar-gravity,a suspended 1/6 gravity simulation system was used for the experiment.When subjects were under different load centroids which include front and back on sagittal plane,left and right on coronal plane,up and down on cross-section plane,near to coordinate origin,the postures and plantar pressures of subjects during three typical movements:standing,single-knee standing and walking were captured.Inverse dynamics solution is adopted to analyze the joint torques of human body in above conditions.Combined with the subjective evaluation,the appropriate load centroid area was analyzed by comparative.The experiment shows that,human is non-sensitive to the up and down change of load centroid,the after is back change,the front and right load centroid are the mostly avoided.The results obtained by this study will provide a reference for the layout design of the lunar spacesuit.

Objective:To explore the short-term efficacy on 3D printing assisted reconstruction of traumatic digit joint defects using rib and costo-osteochondral autograft.Methods:From August 2022 to July 2023, 7 patients with open digit joint defects had undergone emergency primary debridement and fracture fixation in the Department of Orthopaedics, 988th Hospital of the Joint Logistics Support Force of PLA. Patients with more phalangeal defects that could not be aligned were treated with antibiotic bone cement filling in the emergency surgery. In the second stage surgery, bone cement was removed and transfer of rib cartilage graft was performed to reconstruct the digit joint defect. According to a 1∶1 3D printed hand templates, rib cartilage grafts were crafted to the shape of digit joints, and then spliced together the digit joints and bone defects for fixation. Follow-up X-ray examinations were taken and assessment of the healing status of rib and fractures of phalangeal and metacarpophalangeal bones were carried out according to the Paley fracture healing score. At the outpatient follow-up, assessment of transferred joint movement and evaluation of upper limb function were conducted according to the Evaluation Trial Standards of Upper Limb Partial Functional of Hand Surgery of Chinese Medical Association. Visual Analogue Scale (VAS) pain scores were evaluated from the affected digits and donor sites.Results:After reconstructive surgery, all 7 patients had primary healing of the wounds of hand. One patient had fat liquefaction at the donor site, and the rest had primary donor site healing. One patient received further surgery for extensor tendon repair after rib cartilage grafting due to the digital extensor tendon injury. All 7 patients were included in postoperative follow-up for 6-11 months, with an average of 9 months. All patients had excellent fracture healing according to the Paley fracture healing score. At the final follow-up, the extension and flexion of the digit joints were found at 40°-80° (average 56.2°) for proximal interphalangeal joints (4 patients), and 10° in extension and 85° in flexion for metacarpophalangeal joint (1 patient). The range of motion of the thumb interphalangeal joint (2 patients) was 20°-35° (average 27.5°). Hand function was assessed according to Evaluation Trial Standards of Upper Limb Partial Functional of Hand Surgery of Chinese Medical Association and it was found that 3 patients were in excellent, 3 in good and 1 in fair.Conclusion:This study focused on the treatment of traumatic digit joint defects by transfer of individually crafted rib cartilages in reconstruction of the defected digit joint. It significantly improves the appearance and function of the defected digit joints, especially suitable for the irregular defects of phalangeal bones.

Objective:To explore the clinical efficacy of Masquelet technique combined with tissue flap transfer in the treatment of infectious composite bone and soft tissue defects in the early and middle stages after internal fixation for tibial fractures.Methods:From October 2017 to November 2020, 12 patients (13 tibial fractures) with infectious bone and soft tissue defects in the early and middle stages after internal fixation were treated in the Department of Orthopaedics, 988th Hospital of the Joint Logistics Support Force of CPLA by two-phased surgery with retaining internal fixation. Phase I procedures were thoroughly removal of the infected lesions and failed screws, preserving internal implants as many as possible, implantation of absorbable calcium sulphate and an antibiotics blended string of beads into the distal and proximal medullary cavity of the fractured bones, filling the bone defect and wrapping the internal implants with antibiotics loaded bone cement. The size of defects was 3.5 cm × 5.0 cm-7.5 cm × 14.5 cm, and the flaps for wound coverage sized 4.0 cm × 5.5 cm-8.0 cm × 15.0 cm. As for the repair of donor site, 8 limbs were sutured directly, 5 limbs could not be closed completely, and the remaining wounds were covered by skin grafting after suture. Based on well control of infection and stable clinical signs, fillings of bone cement were then removed in Phase II surgery, or 6-9 weeks after primary surgery. Autologous cancellous bone pieces or composite allogeneic bone were fully implanted around the induction membrane formed by Masquelet technique, and auxiliary steel plates were implanted for internal fixation of unstable fractures. After discharge, the patients visited the outpatient clinic regularly, and combined with Wechat follow-up. The texture, colour and bone healing were observed. At the last follow-up, the function of the affected limbs were assessed according to Johner-Wruhs evaluation standard.Results:After Phase I surgery, 13 flaps survived smoothly without vascular compromise. The wounds healed in Phase I. Two patients (2 sides) had recurrent infections. Re-debridement was performed and external fixation was applied after removal of internal fixation. After Phase II surgery, all patients were included in 12-26 months of follow-up, with an average of 18 months. Thirteen lower leg fractures healed well, and the time of bone healing was 16-25 (average 19.5) weeks. The Johner Wruhs criteria was used in evaluation of the function of affected limbs, and it was found that 6 patients were in excellent, 5 in good and 2 in fair.Conclusion:It is feasible while preserving the internal implants, to use membrane induction technique (Masquelet technique) combined with flap transfer, together with the absorbable calcium sulphate antibiotic sustained-release beads as a carrier in the phased treatment of infectious bone defects and bone exposure in the early and middle stages after the surgery of tibial internal fixation. It also gives a higher rate of excellence in surgical outcome. This study explores a treatment procedure for traumatic bone infection combined with composite soft tissue defects.