Knee surgery is all about trying to help the injured knee heal. The joint and its surrounding structures are very complex. The key to success is repairing the damaged structures to be as close as possible to their original state.
The closer we can get to normal anatomy the better the knee will function in the long term.
Arthroscopy involves putting a small camera into the knee to see the structures inside the joint in great detail. This lets us repair and reconstruct damaged areas and remove loose fragments causing trouble.
Early splitting and cracking of cartilage layers can be treated by a technique called chondroplasty. This is using mechanical shavers or radio-frequency tools to smooth the cracked surface. This only works in smoothing the superficial layers of cartilage. If the deeper layers are affected the technique becomes less useful.
- Cartilage Repair
For large full thickness cartilage defects the best option is some form of cartilage repair. This has been an area of great interest over recent years. Various options are possible and are used in different circumstances. Cartilage can be transplanted from one part of the knee to another, cartilage cells can be grown in the laboratory and implanted into the knee or the bone can be stimulated to help new cartilage form.
- Meniscal Debridement
Debridement is the removal of damaged tissue. In Australia this is the most common method of dealing with damaged meniscus. If a small area of the meniscus is torn it can be safely removed without affecting the function of the knee. This is a quick procedure and patients recover rapidly with minimal need for rehabilitation afterwards. This technique becomes less successful if large portions of the meniscus are damaged. If a large part of the meniscus is removed this leads to increased pressure on the joint surface which then starts to get damaged. Eventually this damage can progress to osteoarthritis.
- Meniscal Repair
If a large area of the meniscus is torn then a meniscal repair will be considered. Meniscal repair involves putting stitches or anchors into the damaged cartilage to bring the torn edges together. Once the torn edges are repaired the meniscus may have to be protected to allow the tear to heal. This may involve restricting the amount of weight put on the leg and using a brace. After a suitable period (usually 2-6 weeks) the meniscus will have healed enough to allow a return to normal function. In the long run a successful repair will protect the function of the knee and avoid deterioration to arthritis.
In circumstances where the joint damage is severe joint replacement can be considered.
Joint replacement involves removing part or all of the joint surfaces in the knee and replacing them with metal and plastic components. Total joint replacement involves all of the joint surfaces in the knee. Partial joint replacement involves just replacing one area of the joint surface. This can be very useful when one part of the knee is beyond repair but other areas of articular cartilage are still in good condition. Partial joint replacement can be an attractive option for younger patients as the knee feels more natural than after a total knee replacement. Recovery time is also quicker and function generally better in the partially replaced knee joint than the total replacement.
Usually patients will stay around three to four days in hospital for a total knee replacement or two to three days for a partial knee replacement.
The patella (kneecap) is a common source of knee problems. In some patients the patella will dislocate to the side, in less severe cases the patient may have "mal-tracking" where the patella does not centralise properly in the trochlear groove of the thigh bone.
In most cases this can be dealt with by a patella stabilisation procedure. The medial retinaculum which holds the patella in place can be reinforced or reconstructed. This may be combined with procedures to tidy up or repair the articular cartilage.
In severe cases the shape of the trochlear groove is abnormal and this can be corrected by re-shaping the groove in a procedure called trochleoplasty.
- Anterior Cruciate Ligament Reconstruction
The anterior cruciate ligament (ACL) is injured quite commonly. The injury can occur with a sudden change of direction in sport, a tackle or blow to the knee or with hyperextension of the knee. When the ligament tears there is often a loud pop or crunch, the knee may become swollen and walking will be difficult initially. If the tear is complete a decision has to be made on whether to organise reconstruction.
In young fit people, those who play a lot of sport or people who need a stable knee for their work reconstruction is a good option. In older people, or those who do not mind some knee instability treatment with physio is used to strengthen the muscles around the knee to compensate for the loss of the ACL.
ACL reconstruction surgery involves creating a new structure (graft) inside the knee to do the work of the torn ACL. This graft is most commonly made from two of the hamstring tendons of the injured knee. Other options include using a part of the patellar tendon or the quadriceps tendon.
ACL reconstruction surgery can be done as a day case surgery.
The physio process after reconstruction is very important. The reconstructed ligament needs significant time to heal and strengthen. It is normally recommended to return to sport sport 6-12 months after the surgery.
- Posterior Cruciate Ligament Reconstruction
The posterior cruciate ligament (PCL) is less commonly injured than the ACL. Tears can occur during sports injuries but may also occur in high energy injury such as motor vehicle or workplace accidents. High energy injuries can be associated with injury other ligaments around the knee. The PCL has better healing capacity then the ACL and the need for reconstructive surgery is less. If surgery is required it is a similar type of procedure to an ACL reconstruction using a graft to restore the stability of the injured knee. Healing time is generally slower than with an ACL reconstruction and a brace and restricted weightbearing is normally needed for the first 6 weeks. It is normally 12 months before a return to contact sport.
- Collateral ligament reconstructions
The medial and lateral collateral ligaments can also be injured, either alone or in combination with cruciate ligament injuries. Often these injuries will heal with a brace for a few weeks. When the injury is severe the cruciate ligaments can be repaired or reconstructed to stabilise the knee.
Bone re-alignment procedures can be used in some forms of patella pain and instability. This involves cutting and re-positioning the bone at the tibial tubercle where the patellar tendon attaches.
Bone re-alignment can also be used when the cartilage between femur and tibia is overloaded. Making a cut in either tibia or femur and changing the angle of the bone close to the joint changes the direction of forces across the joint and decreases the pressure on the damaged or reconstructed cartilage surface.