The invention concerns a joint spacer, in particular a knee spacer and a hip spacer. In order to produce a long-lasting joint spacer which is sufficiently cushioned and abrasion-resistant and which can also support locally very high loads, the invention proposes a joint spacer having a Shore-A hardness of between 20 and 77 and tensile stress values at unit strain of between 20 % and 60 %, preferably 50 %, of greater than 3.8 N / mm2, preferably of greater than 4.6 N / mm2 and particularly preferably of greater than 6 N / mm2, and / or compressive stress values at linear compression of between 20 % and60 %, preferably 50 %, of greater than 7.8 N / mm2, preferably of greater than 9 N / mm2, and particularly preferably of greater than 10.5 N / mm2, and / or a Shore-A hardness of up to 85 and tensile stressvalues at unit strain of between 20 % and 60 %, preferably 50 %, of greater than 6 N / mm2, preferably of greater than 7 N / mm2, and particularly preferably of greater than 8 N / mm2, and / or compressive stress values at linear compression of between 20 % and 60 %, preferably 50 %, of greater than 10.5 N / mm2, preferably of greater than 12 N / mm2, and particularly preferably of greater than 14 N / mm2.