Partial knee replacements resurface just one section of the knee that is arthritic. There are 3 main parts to the knee, and most commonly it is the inside or ‘medial’ partial knee, followed by the outside or ‘lateral’ partial knee, then the kneecap or ‘patellofemoral’ that is replaced.
It’s a great operation for those that have had worsening knee pain for several years and its starting to impact on your enjoyment of life. However there is a more stringent criteria on those that are eligible for a partial knee, and patient selection is key to give these implants the best long term outcome and you the best result.
There are over 20 different partial knee replacements used in Australia.
Long term data on the partial knees is less available in Australian Orthopaedic Association, but we use the most commonly utilised partial knee in Australia, which is positioned with the Mako robot. Although we don’t have registry data out to 15 years, at 7 years it has the lowest chance of needing revising to a total knee replacement of all the partial knees placed in Australia.
Implant positioning must be linked in with the ligament balance of the knee to get the best outcome. Robotics have been a big game changer for partial knees, and really helps to reproducibly position the implants in the ideal position to get good bone support, obtain good ligament balancing, and a smooth transition between the implant and the natural bone.
To ensure this we use robotic technology with the Mako, which is arguably the best multiplatform orthopaedic robot in the world with the most robotically implanted joints. Prior to surgery we get a CT scan to ensure we know everything about the knee joint position and its relation to the centre of the hip and ankle, then we plan positioning of the implants looking at the bony anatomy. During surgery we look at the preoperative plan and adjust it slightly depending on how tight or loose the ligaments are within the knee at various positions. We then make sure that only the essential bone is removed, and the implants are positioned perfectly with robotic guidance to give you the best outcome. The haptic boundaries also mean that the saw cuts are constrained to only take away the essential bone, so there is less trauma and less pain. There is good evidence to support a higher satisfaction rate, less pain, shorter hospital stay, earlier rehabilitation and longer implant survival.
After surgery we would expect you to be in hospital 2-3 days, walking with crutches until weeks 2-3, a single stick for support until week 6, then walking without aids. Most of the discomfort and swelling will have resolved by week 4, but wont completely settle until 3-4 months. Physio is important following a knee replacement to help you get your range of motion and reduce swelling quicker.