Progress in mechanobiology allowed us to better understand the important role of mechanical forces in the regulation of biological processes. Space research in the field of life sciences clearly showed that gravity plays a crucial role in biological processes. The space environment offers the unique opportunity to carry out experiments without gravity, helping us not only to understand the effects of gravitational alterations on biological systems but also the mechanisms underlying mechanoperception and cell/tissue response to mechanical and gravitational stresses. Despite the progress made so far, for future space exploration programs it is necessary to increase our knowledge on the mechanotransduction processes as well as on the molecular mechanisms underlying microgravity-induced cell and tissue alterations. This white paper reports the suggestions and recommendations of the SciSpacE Science Community for the elaboration of the section of the European Space Agency roadmap “Biology in Space and Analogue Environments” focusing on “How are cells and tissues influenced by gravity and what are the gravity perception mechanisms?” The knowledge gaps that prevent the Science Community from fully answering this question and the activities proposed to fill them are discussed.

Acquired idiopathic stiffness (AIS) following total knee arthroplasty (TKA) often requires manipulation under anesthesia (MUA). Robotic-assisted TKA (RA-TKA) systems provide gap balance templates for objective correlation with the rate of AIS. The purpose of this study was to assess intraoperative balancing parameters that were associated with MUA utilizing an “anatomical” implant design.We performed a retrospective chart review of 265 imageless RA-TKA procedures performed by R.M. and K.D. between 2018 and 2020. The primary outcome for AIS or clinically significant “arthrofibrosis” was MUA. Patient intraoperative gap planning data were examined for association.The rate of MUA was 8.7% (23/265), which was performed at a mean follow-up time of 75.9 ± 32.2 days. The lateral to medial gap difference in extension was significantly less in patients requiring MUA (odds ratio [OR] = 0.86, 95% confidence interval [CI], 0.75–0.99) (p = 0.034). Significantly less preoperative varus mechanical axis was associated with knees requiring MUA (1.83° vs. 4.04°, OR = 1.09, 95% CI, 1.00–1.19). Decreased templated mechanical axis correction was associated with MUA (2.09° vs. 4.75°, p < 0.0001).A tighter lateral-to-medial gap in extension, less preoperative varus, and smaller templated mechanical axis corrections were associated with increased rates of MUA.

Background: Femoral head fractures with osteochondral defects are rare injuries often resulting from traumatic hip dislocations. These injuries create a significant risk for post-traumatic osteoarthritis. Various surgical methods for repair have been utilized to restore these osteochondral defects, including mosaicplasty, autologous cartilage implantation, osteochondral allograft transplant (OAT), and demineralized bone matrix (DBM). Methods: We present a case of a 21-year-old male who sustained a fracture-dislocation of the left femoral head with impaction of the weight-bearing surface due to a motor vehicle collision. Due to the patient’s relatively young age, OAT plugs from a fresh-frozen proximal humerus with DBM supplementation during fracture fragment fixation were chosen to reduce the likelihood of post-traumatic arthritis. Results: The patient regained subjective function and full strength on exam with no pain at 2 years postoperatively. Conclusions: We propose that a proximal humerus allograft is a suitable alternative in an urgent setting when a femoral head allograft is not available.