The elastic meniscal tissue enlarges the contact area and power transmission between the sliding faces of the lower and upper leg. These days, we have a good deal of knowledge regarding the significance of this " buffer". The meniscus fulfils a number of tasks. It disperses about 30-70% of total weight-bearing; after a meniscectomy, the stress load increases by a factor of 2.5-6! The meniscus is responsible for shock absorption, lubrication of the joint and plays a major role in stabilization of the knee. In 1948, Fairbank described radiological changes following open meniscectomy, i.e. the excision of the meniscus through an incision in the skin. He was able to demonstrate that the increased wear of the joint was proportional to the amount of meniscus that had been removed. Nowadays modern arthroscopic techniques allow us in the majority of cases to preserve most of the meniscus and thus significantly to improve functional long-term results. The causes of meniscus ruptures can be traumatic or degenerative. It is three times more common for ruptures to occur on the inside of the knee than on the outside.
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| Typical meniscus rupture |
Rasping of the meniscus to prepare for suturing |
Because of the well-known long-term effects of a meniscectomy, it is our foremost aim to do whatever we can to preserve as much of the meniscus as possible. A meniscal tear can form flaps or bucket handles which can be stitched back into place. Good healing rates have been reported for sutured meniscal injuries in the "red zone", i.e. the well-vascularized zone at the base of the meniscus. In each individual case, it is up to the experienced surgeon to decide during the operation whether suturing the torn meniscus is an option.
In the Centre for Orthopaedic Surgery Pfaeffikon, we use state-of-the-art suturing techniques, which not only ensure smooth procedures, but also promise a good chance of recovery. These techniques, known as "all-inside" - in contrast with previously used "inside-out" or "outside-in" techniques - avoid damage to nerves and blood vessels.
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| Meniscus suture with reabsorbable anchors |
Reabsorbable suture anchors for meniscus fixation (Bionx Implants Inc.) |
Meniscus replacement with a collagen meniscus implant (CMI)
Even though patients generally regain normal functionality of the knee following a meniscectomy, studies have shown that the removal of meniscal tissue results in a decrease of the contact area and thus an increase of contact pressure, which can ultimately result in the development of degenerative arthrosis of the knee joint.
The collagen meniscus implant (CMI) is a treatment alternative to the partial meniscectomy of the medial meniscus. The CMI is a reabsorbable collagen scaffold that prevents or delays progressive degenerative changes in the knee joint. It constitutes a biological alternative to the loss of meniscal tissue after a partial meniscectomy. The implant is similar in size and form to the human meniscus. It can be easily trimmed to the required size during the operation to fit into the prepared area of defect. Sutured into place, the CMI then acts as a guide rail for the influx of the body's own cells. Over time, in parallel with the increasing regeneration of tissue, the CMI is gradually reabsorbed by the body, leaving behind new meniscus-like tissue. This new tissue is able to restore the functionality of the meniscus. Pain levels are reduced, and the degenerative process that begins with the loss of meniscal tissue is potentially put on hold.
CMI (collagen meniscus implant
(Zimmer Holdings Inc.)
If the whole meniscus has been removed, a donor meniscus may be used in some instances.
Following meniscus replacement, crutches have to be used for 2-3 months to reduce weight-bearing in order to allow the implant to integrate. Whether health insurers will foot the costs needs to be clarified in each individual case.
Our current position is as follows:
The meniscus is important for the dispersion of stress and, as a shock absorber, contributes towards the lubrication and stability of the knee joint. The meniscus has the capacity to heal. Wherever possible, the meniscus should be preserved. At the present time, suturing the meniscus is still the more practicable approach, but meniscus replacement surgery is becoming more common. As a basic rule, any meniscal damage should be repaired as early as possible in order to avoid subsequent damage by arthrosis.
Arthroscopic meniscal surgery
The procedure aims to preserve as much of the healthy meniscal tissue as possible and to remove the diseased tissue. In some cases, the use of a high-frequency electrosurgical knife in addition to microsurgical instruments allows the procedure to be even gentler. Partial removal of the meniscus results in a small reduction of the contact area; however, depending on the size of the removed section, this does not have a negative effect on the functionality of the joint. Whenever possible and practical, the meniscus is preserved by using meniscal suturing; if the meniscus has already been removed, a meniscal implant might be attached(see above: CMI). In order to encourage healing of the torn meniscus sections and to enable revascularization, the torn sections are prepared with microsurgical instruments (needling and rasping) prior to suturing. In some cases when the meniscal tear is only small and there is a simultaneous rupture of the cruciate ligament, this may be sufficient and no suture may be required.
We carry out most meniscus operations under general or local anaesthesia. Your anaesthetist will advise in detail and agree with you on the procedure that is best for you. Under local anaesthesia, you can follow the procedure on the monitor; the individual steps of the operation will be explained to you, If you want, the whole operation can also be recorded on a blank VHS cassette provided by you.
After discharge
You should not place your whole weight on the operated leg; the best advice is to elevate the leg and, during the initial days, to cool it with a dry ice-pack several times a day for about 10 to 15 minutes at a time.
Medication
At home, you will continue to take as prescribed:
- Diclofenac (e.g. Voltaren Dispers) or paracetamol relieve pain and have an anti-inflammatory effect. Recommended dosage: 3 x 1 tablet.
- Anti-thrombotic injections, e.g. Fragmin®, for 5-14 days, to be injected into the abdominal skin, as shown to you in hospital.
Aftercare
After resting for two to three hours, stand up and walk a few paces. Activating the muscles of the lower leg is the best thrombosis prevention that you can implement yourself.
Stitches are generally removed after 14 days. After a partial meniscectomy, you can generally place your full weight on the leg again after using crutches for five days.
After a meniscus suture, you should not bend the knee under stress by more than 90° in the first six weeks (don't squat!). Other than that, you can place your full weight on the fully extended knee after 10 to 14 days.
Following meniscus replacement, crutches have to be used for 2-3 months to reduce weight-bearing to allow the implant to integrate.