Arthrosis / Knee arthroplasty
Arthrosis is defined as a degenerative condition characterized by the wearing of the cartilage covering the bone ends in a joint. Articular movements are enabled by the sliding of cartilaginous surfaces at the femur’s lower end, the tibia’s upper end, and the posterior side of the patella.
Over time and with use, cartilage thickness decreases, and its surface gets uneven, leading to painful movements. X-rays show a narrowed joint space whose extent depends on the severity of osteoarthritis. When the cartilage is completely worn out, articular contact is made between the bones, causing a lot of pain. In this event, X-rays show that the narrowed joint space has vanished, and sometimes reveal bone wear and osseous outgrowths called “osteophytes” as well. Osteoarthritis often arises in conjunction with degenerescence and meniscal lesions.
Main causes of cartilage wear:
- Osteoarthritis: Osteoarthritis of the knee (gonarthrosis) may be caused by overweight, joint fracture after-effects, inward (varus) or outward (valgus) lower limb misalignment, old cruciate ligament ruptures, and meniscus removal;
- Rheumatoid arthritis or other inflammatory rheumatisms;
- Osteonecrosis, involving mostly the femur.
The best surgical option is set according to the extent of cartilage wear, the patient’s age, and the type of osteoarthritis.
a- Cartilage graft :
Damaged cartilage does not regenerate, and replacing this worn cartilage with new cartilage is every patient’s and doctor’s dream. To this day, it is impossible to fix extreme cartilage wear due to osteoarthritis.However, cartilage grafts can be performed in a few particular cases: The wear has to be limited to a few square centimeters, the cartilage around the lesion has to be in good condition, and the injury has to be located on the femoral condyles. This graft is made so as to prevent future osteoarthritis induced by the lack of cartilage.
Two procedures are currently available: mosaic surgery and cartilaginous cells transplant.
- Mosaic surgery involves taking small bone samples and their cartilage cover from the knee. This procedure is performed arthroscopically. Walking is possible with the aid of a cane for 3 weeks. As this is a new procedure, its long-term results are still unknown.
- Cartilaginous cell transplant is a much more difficult and expensive procedure that necessitates two operations, the second of which creates two scars. This procedure has rarely been practiced, and the number of cases treated this way is very low.
b– Osteotomy :
Cartilage wear that is limited to a compartment of the knee (internal or external) accompanied by a misalignment of the limb can be treated with osteotomy in order to realign the deformed limb and transfer the damaged compartment’s weight to the healthy one. However, the healthy compartment will wear out as well in the future.
Osteotomy is usually performed on patients under 60 years of age. This intervention protects the damaged compartment for around 10 years.
Osteotomy is usually done on the tibia. Two procedures are available:
- Opening wedge osteotomy: This is the most frequently employed procedure.
It involves cutting the tibia along a cut line and spreading the edges to insert a piece of mineral bone.
- Closing wedge osteotomy: This procedure involves removing a piece of bone from the tibia. A portion of the fibula has to be severed as well.
In both cases, fixation is secured using osteosynthesis equipment (nail-plate fixation) that is removed 2 years later (ambulatory surgery). The patient should walk with crutches and keep the splint for 6 weeks while taking anticoagulant treatment. Resumption of normal everyday life is possible 8 to 10 weeks after surgery
c- Knee arthroplasty
The first knee prostheses were developed about 30 years ago and changed the lives of many patients who could barely walk without pain. Placing knee prosthesis should be considered when pain, disability or effusions get worse, and medical treatments (anti-inflammatory drugs, infiltrations, viscosupplementation) are ineffective to the point where standing up, going upstairs, and walking become a problem. The patient has to decide according to his level of disability.
The surgeon can either replace the entire knee or part of the articular surfaces on the femur, tibia, and patella with a prosthesis made out of two to three different implants:
The femoral prosthesis (made out of chromium and cobalt) will slide on the polyethylene tibial plateau.
The tibial prosthesis comprises two parts:
- a metal plateau made out of chromium and cobalt or titanium and anchored to the tibia
- a polyethylene plateau resting on the tibial metallic plateau. This plateau can be either fixed or rotational. It ensures friction between the tibia and the femur.
The kneecap polyethylene prosthesis is only used when the patellar cartilage is severely worn-out.
Placing a prosthesis is a very common, well-standardized procedure, which usually takes 1 hour to 1.5 hours, depending on possible complications during surgery.
Placing knee prosthesis can be done using computerized monitoring, which allows for accurate positioning of the prosthetic parts.
The application system can be tailor-made based on MRI data obtained prior to the procedure. A “navigation” system can also be used.
Postoperative pain is managed using strict pain control protocols and by inserting a catheter at the root of the thigh in order to insure postoperative analgesia.
Anticoagulation and support stockings are prescribed so as to prevent phlebitis.
1- Unicompartmental knee arthroplasty
If the knee damage is limited to the joint’s inner side or to its outer side, the injured part’s articular surfaces can simply be replaced.
Single compartment prostheses are indicated in the following cases: The injury is limited to one of the tibiofemoral compartments (the other compartments are healthy), the cruciate ligaments are intact, the body mass index is below 30, there is no stiffness in the knee, and the deviation is less than or equal to 15°.
As previously mentioned, this prosthesis includes a femoral implant, a tibial implant, and a pad that only replace “half of the knee.”
Incisions and the surgical approach in general are less invasive than a few years ago, thanks to improvements in equipment and procedure. These new techniques are called minimally invasive surgeries (MIS).
This procedure involves a skin incision (6-8cm), an opening of the knee without cutting tendons or muscles more than 1cm, spreading the patella without reversing it, and equipment adapted to this minimally surgical approach.
This procedure facilitates faster recovery and decreases pain and bleeding.
Once the bone slices are made and the trial implants placed, ligament balance and stability during knee flexion are checked.
All of these benefits combined with pain control protocols allow for easier postoperative recoveries and shorter hospitalization periods.
2 – Tolal knee arthroplasty
- This type of prothesis completely replaces the joint, except for the patella, which can be left without putting a polyethylene button prosthesis (provided the cartilage is still in good condition).
Aside from the joint reconstruction, the procedure allows for the reduction of preoperative deformations (varus or valgus on the lower limb).
Ligament balance and stability and patellar alignment are checked once the bone slices are made and the trial implants are placed. Kneecap resurfacing through a polyethylene button is not mandatory.
Patients’ blood is recovered during and right after surgery (Cell Save), which reduces the need for blood transfusions. Your blood is recovered during and right after surgery (Cell Saver) which reduces transfusions.
Your questions on prosthetic knee surgery
5 to 6 days
Anesthesia of the lower limb’s nerve trunks will be induced prior to surgery under ultrasound control. A crural catheter will also be placed to ensure postoperative analgesia. This local anesthesia will be additional to a light general anesthesia during the surgical procedure.
Returning home is possible, provided the patient’s family can take care of him. Otherwise, it is better to stay in a rehabilitation center for a few weeks.
Blood transfusions can be avoided with the use of a Cell Saver during surgery. Also, for patients with low hemoglobin levels, erythropoietin (EPO) may be administered before the procedure.
A month after surgery, most patients can start walking without crutches and drive their cars. Rehabilitation should continue for 2 to 3 months. Resumption of recreational sports like biking, playing tennis, or skiing is possible.
During the procedure, in cases of significant osteoporosis or bone fracture, we might have to install a prosthesis with longer anchoring skittles or osteosynthesis equipment. Vascular or nervous injuries may occur and require proper treatment. These complications remain uncommon, especially when the surgical team is very experienced in this type of procedure.
After surgery, power Doppler ultrasonography will be used to check for phlebitis if it is suspected during the clinical examination. Urine retention may occur (especially to male patients) due to the local anesthesia, and could require catheterization. An infection may occur days after surgery. This complication is very uncommon.
Later on, algodystrophy may cause pain and stiffness or delay rehabilitation. This phenomenon usually decreases over the following months.
Prostheses usually last for 15 years.