https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0139-0 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0141-6 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0138-1 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0140-7 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0143-4 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0131-8 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0134-5 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0137-2 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0132-7 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0128-3 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0135-4 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0133-6 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0136-3 https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0142-5