## 5 Conclusions  
This study demonstrates the influence of sterilization and degradation process on the compressive strength, pore size distribution, weight loss and molecular properties of PLA in composites made of polymer and HA included as a form of whiskers or hexagonal rods. The PLA was in the amorphous state before and after the preparation, sterilization and degradation of composites. The main conclusions could be stated as follows:  
1. Sterilization led to a reduction of \(M_{\mathrm{w}}\) of PLA and, furthermore, a change in the pore size distribution of composites depending on \(M_{\mathrm{w}}\) and HA added.
2. Similarly, degradation reduced the \(M_{\mathrm{w}}\) of PLA, but did not substantially change the compressive strength of tested materials.  
3. Degradation of PLA occurred as reduction of polymer mass was greater in the control sample of high \(M_{\text{w}}\), compared to HA-filled materials, indicating the lower rate of PLA degradation when HA is incorporated into the PLA matrix.
4. There was no major impact of HA morphology or metal inclusion on mechanical properties and weight loss of produced composites.
5. All produced materials should be recognized as cytocompatible when validated against L929 mouse skin fibroblasts and hFOB 1.19 human osteoblasts. The lack of cytotoxicity was accompanied by the immunocompromised with human monocytic cells.  
M.K.: conceptualization of article, tests analysis, writing, A.S.: preparation of samples, investigation (mechanical strength tests, density, weight loss, hydrolytic degradation), A.K. ([PERSON]): methodology (degradation process), P.T.-G.: investigation (SEM observations), A.N.: preparation of samples (synthesis of hydroxyapatite), A.W.: investigation (thermally induced phase separation, degradation process), A.A.: investigation (X-ray diffraction), J.P.: investigation (differential scanning calorimetry), P.S.: methodology (synthesis and modification of HA), A.P.: molecular weight (gel-permeation chromatography) supervision, P.W.: tests analysis, P.R.-W.: investigation (in vitro cytobiocompatibility), A.K. ([PERSON]): writing, P.P.: writing, K.R.: conceptualization of biological analyses, M.B.: conceptualization of work, supervision. All authors have read and agreed to the published version of the manuscript.  
The Foundation for Polish Sciences granted the project \"Multifunctional composites biologically active for applications in regenerative medicine of bone system\" (POIR.04.04.00-00-16D7/18) that was carried out within the TEAM-NET programme financed by the European Union under the European Regional Development Fund.  
Not applicable.  
The data generated during this study are available at LUKASIEWICZ Research Network Institute of Ceramics and Building Materials, Center of Ceramic and Concrete in Warsaw, Biomaterials Research Group, Postepu 9, Warsaw, 02-676, Poland, and are available from the corresponding author upon request.  
The authors declare no conflict of interest.
Figure A2: XRD analysis of hexagonal rods.  
Figure A3: XRD analysis of whiskers with Zn.  
Figure A5: DSC curves for PLA under investigation (pure granulates).  
Figure A10: DSC curves for Low \(M_{\rm w}\) PLA + HA rods composites at different stage of studies—after preparation, after sterilization and degradation.  
Figure A11. DSC curves for Low \(M_{\rm w}\) PLA + Sr-HA rods composites at different stage of studies—after preparation, after sterilization and degradation.  
Figure A12. DSC curves for High \(M_{\rm w}\) PLA + HA whiskers composites at different stage of studies—after preparation, after sterilization and degradation.