Meniscal Injuries of the Knee
Meniscal Injuries of the Knee
The normal knee contains two semicircular discs lining the joint line known as menisci. These are composed of an elastic fibrocartilage and provide the important job of "shock absorbers" thus reducing stresses through the joint and limiting abnormal wear. They also perform a secondary role in contributing to knee joint stability.
Mechanism of Injury
The knee is commonly involved in work-related injuries. The meniscus is particularly prone to a combination of flexion and rotation of the knee. This often occurs in work-related settings such as heavy load bearing.
Injuries to the meniscus generally result in tears which lead to acute pain, swelling and stiffness. In addition if a fragment of the torn meniscus is caught between the knee joint surfaces this can result in the knee getting stuck or "locked" with certain activities resulting in severe pain and inability to walk. This results in great difficulty returning to normal work duties.
Natural Progress
As there the meniscus has only a limited blood supply in an adult, there is little potential for spontaneous healing in all but small and incomplete tears. If not appropriately treated the problem is of ongoing pain and swelling which will impede rehabilitation and fitness for work.
Investigations
Following an acute work related knee injury, the investigations ordered depend on the clinical findings on examination of the knee. It is reasonable to have an Xray performed to exclude any fractures but this does not actually demonstrate a meniscus tear. As such this may require a special CT or MRI scan to show it.
Treatment
While it would be reasonable to attempt physical rehabilitation in the first instance to accelerate fitness for work, if the knee does not respond quickly to this then surgical intervention may be required. The technology now exists to perform this through arthroscopic or "keyhole" surgery. This is generally performed under a general anaesthetic with the patient asleep.
The injury to the meniscus is assessed and in a small proportion of patients a tear may be repairable. However due to the fact that the meniscus has a poor blood supply and that most tears often result in several fragments, in most cases the torn fragments need to be removed. As much of the remaining normal meniscus is left intact and is trimmed to a smooth surface.
Physical Rehabilitation
Arthroscopic surgery is generally performed as a day case. Depending on the specific problems with the knee most patients can start full weight bearing on crutches immediately following the surgery. Sufficient pain relief is organized and rehabilitation commences immediately. This primarily involves range of movement exercises and strengthening of the quadriceps muscles. A physiotherapist can be helpful in assisting with this.
In general patients are comfortably weight bearing and walking without crutches by approximately two weeks following surgery. At this stage fitness of work would be reasonable to consider for office based duties and some manual jobs. Physical rehabilitation increases at this stage and can include hydrotherapy and muscle strengthening exercise. In general fitness for work for heavy manual labour can be considered between two to four weeks following surgery.
Work Restrictions
Following arthroscopic surgery, the patient should avoid prolonged standing and walking and any twisting movements or deep flexion (such as kneeling) for the first two weeks. Thereafter work-related activity levels can be increased and by six weeks following surgery, few work restrictions generally apply.
Prognosis
In general most patients recover well from work-related meniscus injuries of the knee if they are appropriately treated. There is a theoretical concern of potential arthritic changes occurring after removal of part of the meniscus due to loss of some of the "shock absorbing" capacity. However in general only the abnormal and torn part of the meniscus is removed leaving as much of the normal meniscus intact as possible. The outcome following removal of a torn meniscus is also far better than leaving a fragment locked between the joint surfaces.
Disclaimer: Please note that the information in this article is intended as only a general guide to injuries of the meniscus. Every patient's clinical situation will differ and treatment is modified depending on the specific problems and needs of each patient.
Dr. Rezah Salleh
Orthopaedic Surgeon
MBBS(UWA) FRACS
Suite 217 Saint John Of God Subiaco Clinic
25 McCourt Street
Subiaco WA 6008
Phone: (08) 9382 9102
Fax: (08)9382 9104Labels: Knee injuries
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