Knee replacement involves resurfacing the top of the tibia (shin bone), end of the femur (thigh bone) with metal components and a polyethylene (plastic) bearing component. A plastic button is usually applied to the back of the patella (knee cap) too.
FAQsWhat is knee arthroscopy? Arthroscopy involves looking inside the knee with a keyhole camera inserted through a small 1cm incision (portal) on the front of the knee. A second portal is made to introduce other instruments in order to perform surgery inside the joint. Other portals are made as needed depending on what exactly is being done.
FAQsThe knee is a hinge joint which bends backwards and forwards but also rotates. The ACL is one of the stabilisers of the knee. It stops the tibia (shin bone) from sliding forwards under the femur (thigh bone). It is also an important stabiliser to rotation in the knee. It is especially important when moving side to side, changing direction and landing from a jump.
FAQs
The most common type is a total knee replacement (92%) where the whole joint is replaced. In Australia 8% of knee replacements are a unicompartmental (partial) knee replacement. This involves replacing only the diseased portion of the joint and is appropriate where the arthritis is localised to a single part of the joint (medial, lateral or the patellofemoral joint). A partial knee replacement is a smaller operation with a quicker recovery, but only the minority of people have the right knee for it.
No one NEEDS a knee replacement. People elect to have a knee replacement when their symptoms are severe enough. For most people the main symptom is pain and when the pain affects their quality of life, keeps them up at night or they are relying on heavy duty pain killers then it is time to consider surgery.
You will be walking as soon as possible – either the same day or the next morning. Most people stay in hospital for 1 or 2 nights. Walking gradually improves over the next few weeks. Most people stop using their frames/walkers/crutches between 2 and 6 weeks after their surgery. Driving is normally restarted at the 6 week mark. Because the knee is not a well padded joint in most people, any swelling remains very obvious. It is normally around 3 months before the knee returns to normal and people are happy that they have had the surgery.
Yes. It is a major operation and all surgery carries risk. The general risks of surgery include bleeding, infection and blood clots. Specific risks include fractures, ongoing pain and nerve or blood vessel injury. Dr Gieroba will talk to you in detail about risks during your consultation.
Modern knee replacements in Australia for arthritis have a revision rate of 8% at 20 years – this means that after 20 years 92% of knee have not been re-operated on. The most common reasons for revision surgery in Australia are infection, component loosening and pain.
In Australia, 83.7% of people with a knee replacement are either “satisfied” or “very satisfied” with their knee replacements. They are not quite as satisfying for patients as hip replacement. A small proportion of people are not happy with their knee replacement.
The most common reason for a knee arthroscopy is to deal with a torn meniscus. Most meniscal tears which need surgery are treated with a simple debridement (or trim) of the torn portion of the meniscus. Other reasons for arthroscopy include: washing out an infection, removing loose bodies or sampling the lining of the joint as a biopsy. More complex procedures such as repair of meniscal tears, or cartilage defects or even cruciate ligament reconstructions can be done arthroscopically.
This varies according to what was actually done inside the knee. For most simple arthroscopic procedures with trimming of torn cartilage, weight bearing is allowed but with 2 weeks of taking it easy to let the portals heal. More complex procedures such as repairs or reconstructions may need time non-weight bearing or with other restrictions.
A meniscus is the shock absorbing cartilage in the knee. There are two, one on the medial side and one on the lateral side. They act as a cushion and almost like an adaptor between the flat top of the tibia (shin bone) and the curved end of the femur (thigh bone).
Like all injuries, menisci can be torn from a sudden major knee injury or from gradual wear and tear. For example, around half of ACL injuries have some sort of meniscal injury too. The other type of injury is a chronic wear and tear – an accumulation of minor injuries which eventually damage the meniscus.
Like skin wrinkling, meniscal wear is a normal part of ageing. Only tears which cause symptoms may need surgery. The typical symptoms from a meniscal tear are mechanical symptoms; clicking, clunking, a feeling of instability or the knee physically getting stuck.
The meniscus has a poor blood supply and so has a limited capacity for healing itself. Almost all symptomatic tears in younger patients with healthy knees do benefit from surgery. In older patients or those with worn out knees, some tears can be left alone while others which cause symptoms can benefit from surgery.
Some tears are repairable. This depends on the nature of the tear, where exactly it is and what the condition of the rest of the knee is like. Depending on the exact tear configuration and stability of the repair, sometimes a period of protection with crutches or even non-weight bearing for 6 weeks is needed. Because of this, most meniscal repairs are planned ahead of time. It is rare to go into surgery expecting to simply trim a meniscus but instead finding that it is repairable. There are many ways to fix a meniscus depending on the type and location of the tear. Common methods include using suture devices completely inside the knee, through tunnels in the bone, or through larger incisions on the knee.
Tears which are not repairable (the majority) are trimmed back to a stable base. Removing the whole meniscus (as was historically done) improved symptoms quickly but had a high risk of progressing to knee arthritis. Nowadays only the torn portion of the meniscus is removed, leaving behind as much meniscal tissue as possible as long as it is stable and functional. It is much like having a torn fingernail and just trimming the torn portion to make the edge smooth.
The trend has now moved away from arthroscopy for uncomplicated knee arthritis. Osteoarthritis is a wear and tear process where the cartilage in the knee wears aways. This includes the smooth cartilage on the ends of the bones as well as the meniscus. Unless there are obvious mechanical symptoms (clicking, clunking or locking) which can be attributed to a meniscal tear or loose cartilage flap, arthroscopy is unlikely to make a significant difference. Also, in the setting of arthritis, pain may persist even after a meniscal tear is dealt with as some of the pain may be coming from the arthritis rather than the torn meniscus.
No. Some people are very lucky and the ACL heals in a functional position and continues to do its job. This is quite rare. In some people, despite some increased knee laxity, they have minimal symptoms and can get by without an ACL. Around about half of people by age 50 no longer have a functional ACL. A knee rehabilitation program directed by a physiotherapist can help strengthen and co-ordinate knee muscles to compensate for an ACL deficiency.
For people whose knee instability prevents them from doing what they need or want to do (sports, work, sometimes even just walking) they do benefit from an ACL reconstruction.
The ACL is like a rubber band and when it ruptures it stretches out and becomes damaged. Additionally, because the ACL sits inside the joint, cells which are trying to heal and repair the ACL get washed away by the normal joint fluid. Because the remaining ACL tissue tends to be no good, tissue is brought from elsewhere to replace the ACL.
The common graft options include the patient’s own hamstring tendons, the quadriceps tendon or the patellar tendon. All of these options have their own advantages and disadvantages. Other less commonly used options include allograft (from a deceased donor), or rarely a synthetic ligament.
Dr Gieroba is familiar with modern reconstructive techniques. In most cases he will use a hamstring graft – aiming to use only one of the tendons (semitendinosus) to make a 4-stranded graft. If this is thick enough then the other tendon is left alone. In some cases, the graft is too thin with a single tendon so the other tendon (gracilis) is harvested too. There is evidence that thicker grafts have a lower re-rupture rate. For some people, other graft options are a better choice and at your consultation the options are discussed.
Once the graft is prepared, the inside of the knee is assessed with an arthroscope and any other problems dealt with at the same time. A tunnel is then drilled in the tibia and the femur to pass the graft through the knee joint to recreate the original ACL position. Fixation is typically performed with a suture button device on the outside of the bone on the tibia and femur.
There is no such thing as a free lunch. Every graft option has its own advantages and disadvantages. These are discussed at the time of your consultation but in general, harvesting a hamstring results in some hamstring weakness, patellar tendon graft carries a risk of fracture and arthritis, quadriceps harvest results in some quadriceps weakness and using a deceased donor tendon has a higher re-rupture rate.
Typically when the ACL ruptures the next structure that stops the knee from dislocating completely is the meniscus. This is not what the meniscus is designed to do and around 50% of ACL injuries also cause some sort of meniscal tear. These meniscal tears can be stable and heal on their own, or they may need to be repaired at the time of ACL surgery.
Other ligaments can be injured too, most commonly the MCL or medial collateral ligament. This is a broad ligament on the inside (medial) side of the knee which stops the knee from bending sideways. The majority of MCL injuries heal well without needing surgery. Sometimes ACL surgery is delayed for 6 weeks to give the MCL a change to heal.
When the knee gives way, the femur and tibia crash into each other in an abnormal way. This often causes bone bruising which can remain painful for months. It can also damage and detach part of the smooth cartilage on the end of the bone. Loose cartilage sometimes needs to be reattached.
A knee with an ACL injury has an increased risk of arthritis in the long term. ACL reconstruction does not seem to reduce this risk. This is likely to do with the cartilage damage being caused by the injury itself when the ACL was first injured. Episodes of knee instability and giving way in an ACL deficient knee may cause further damage to the meniscus and joint cartilage.
Because the ACL is an important stabiliser to rotation, certain groups of patients benefit from an extra procedure to help control pivoting in the knee. Dr Gieroba decides this on a case by case basis, but certain risk factors such as having hypermobile knees, being young (< 25 years old), playing high risk sports, re-do ACL cases and patients with a lot of pivot instability are likely to benefit. The procedure involves a cut on the outside (lateral) side of the knee (around 5cm long), and a portion of the deep fascia of the leg is harvested and inserted onto the femur. It reduces the risk of re-rupture of the ACL graft in high risk patients from 11% to around 4% and does not affect the rehabilitation or over-tighten the knee. The downsides are that it involves an extra incision and takes around 15 minutes longer.
The rehab is long. The aim is for a return to sport at the 12 month mark once rehabilitation milestones are met and an MRI demonstrates successful graft healing. There is evidence that an earlier return to sport is associated with a higher re-rupture rate. A physiotherapist oversees the rehab and progresses you when you meet certain milestones.
Rehabilitation is progressed based on meeting certain milestones rather than being strictly time based however in general the timeline is:
In general, all surgery has certain risks. These include bleeding, infection and blood clots. All are rare with ACL surgery and blood thinners tend to not be needed. Infection is rare but is typically treated with a wash out and antibiotics.
Important risks specific to the ACL include stiffness. One of the most important parts of early rehabilitation is to get the knee moving again as the insult of surgery tends to want to stiffen the joint. Some pain in the back of the knee with hamstring harvest or the front of the knee from general weakness can occur. There is also a risk of graft rupture. This could be due to a re-injury, returning to activity too soon, surgeon error or simply bad luck. A re-do reconstruction using a different graft is possible following failed surgery.
Dr Gieroba will have a detailed discussion about surgical risks at your consultation.
Surgery is an insult to the joint, as is the ACL injury itself. Both things happening too close to each other carries a risk of ongoing stiffness in the knee. In general, ACL surgery is delayed until there is enough knee movement to proceed to surgery safely. For most people this is within 6 weeks and can be as soon as 1 or 2 weeks. What we aim for is full extension of the knee, and bending to at least 90˚. Your physiotherapist can help with “pre-hab” which involves getting the movement back, then starting strengthening of the quadriceps and hamstrings ready for surgery.
Because the old ACL is being replaced with new tissue brought in from elsewhere, there is no significant urgency to get to the surgery straight away.
Burnside Hospital - Stepney
