A pork loin joint or pork loin roast is a larger section of the loin which is roasted. It can take two forms: 'bone in', which still has the loin ribs attached, or 'boneless', which is often tied with butchers string to prevent the roast from falling apart. pork loin joint or pork loin roast is a larger section of the loin which is roasted. It can take two forms: 'bone in', which still has the loin ribs attached, or 'boneless', which is often tied with butchers string to prevent the roast from falling apart.