Total Knee Replacement: Common Questions

Most last a very long time. Australian Orthopaedic Association National Joint Replacement Registry data indicates that over 85% of knee replacements are still functioning well 23 years after surgery. Longevity is not determined by the implant alone — activity level, body weight and how the joint is loaded over the years all matter. A younger, highly active patient may wear an implant faster than an older, less active one.

Usually between one and one and a half hours, though this varies with the complexity of the case. The full process takes longer than the operation itself once anaesthetic, preparation and recovery-room time are included, so expect to be away from the ward for several hours.

Typically a spinal anaesthetic together with a nerve block for post-operative pain control, plus sedation so you are asleep. A cannula is placed in your arm for medication. The nerve block means the leg often stays numb for some hours after surgery, which is expected.

MBS item 49518 is the code commonly used for total knee replacement in Australia, including patella resurfacing where performed. Item numbers and scheduled fees are revised periodically, so confirm the current code and fee with the rooms when you are quoted.

Around six weeks is typical, but the calendar is not the test. You must be off opioid pain medication, able to sit comfortably and work the pedals without pain, and able to perform an emergency stop safely. Right knee surgery, and driving a manual, generally take longer. Do a test drive somewhere quiet before returning to the road, and check your insurer's position.

It depends on where you are starting from. Patients who ran beforehand can often return gradually with focused rehabilitation. If you did not run before surgery, taking it up afterwards is generally not advised — a knee replacement is a mechanical joint, and high-impact loading wears it faster. Low-impact activity such as swimming and cycling is the better long-term choice.

Two common causes. If you had a fixed flexion deformity before surgery — a knee that would not fully straighten — the surrounding muscles, ligaments and tendons remain tight even though the joint can now extend, and stretching them out is uncomfortable. Swelling inside the knee can also press on the capsule at the back. Both are usually part of normal recovery.

No, and this one matters. Resting with the knee slightly flexed relieves discomfort in the short term, but held habitually it encourages fibrous tissue to form behind the joint and can permanently limit your ability to straighten the leg. Work on full extension even though it is the less comfortable position.

Overexertion. Soft tissues need time to heal, and feeling better is not the same as being healed. Keep to the physiotherapy you have been given rather than adding to it, then step activity up gradually from around the two-week mark.

Raise it with your surgeon and your dentist rather than assuming either way. Infection anywhere in the body can potentially reach a joint replacement through the bloodstream, so significant dental work warrants a conversation. Report fever or unexplained pain in the joint promptly at any time.

Usually two to four nights. Discharge depends on four things: pain controlled with tablets, a dry dressing, a physiotherapist satisfied you can move about safely, and normal bladder and bowel function. Some patients transfer to a rehabilitation ward for additional physiotherapy first.

Less than most people expect — usually about 5 to 7 mm from the ends of the femur and tibia, rather than large sections of the thigh or shin bone.