22 T H E AUSTRALIAN JOURNAL OF PHYSIOTHERAPY

INJURIES ABOUT THE KNEE JOINT W. D. STURROCK, M.B., B.SV F.R,C.S.

Sydney

The knee joint is different from other joints in that it allows great mobility in one plane and it has extraordinary stability in any position in that plane. This stability depends not on the shape of the joint surfaces, but entirely on the ligaments about the knee and on the muscles and tendons which move the joint. If these muscles are weak the knee cannot be stable, especially when it is flexed; that is why the role of the physiotherapist is so impor­tant in the treatment of injuries of this joint

ANATOMY As far as the bony structures are con­

cerned, the curved condyles of the femui do no more than rest on the almost flat surfaces of the tibia and the menisci on each side add very little to the depth of the socket of the joint. In front, the quadriceps mechanism with the patella and tendon is of prime importance. Behind, the hamstring group of tendons and the muscles passing from femur to the tibia are mainly concerned with mobility of the lower limb. On each side, there are lateral ligaments on which the lateral stability of the joint almost entirely depends. The medial ligament, from a small attachment to the femur, has a broad fan-shaped attachment to the tibia which extends well down the bone, and to this ligament the medial meniscus is fixed. Laterally, the stout round cord of the lateral ligament extends from femur to head of fibula well away from the lateral meniscus.

The cruciate ligaments, which we may refer to as being inside the joint, although strictly speaking they are not so, prevent backward and forward movements when the knee is in varying degrees of flexion, the anterior cruciate ligament being tight in extension and the posterior in flexion.

Inside the joint, the menisci are present and the smooth lining of articular cartilage is lubricated by synovia! fluid.

INJURIES AND THEIR MANAGEMENT Injuries can occur to any of these struc­

tures in varying degrees of severity, and these will now be considered in turn.

The Quadriceps Mechanism In children, the attachment of the patella

tendon may lift off the epiphysis of the tibia! tuberosity and upper tibia like a hinge; it has to be replaced by manipula­tion or operation and the knee immobilized for six weeks in extension.

In the elderly, the quadriceps tendon may rupture and a gap is found just above the patella which requires suture and fixa­tion in plaster for six weeks.

The common injuries are those occur­ring to the patella. Dislocation laterally may be the result of a blow on the medial side in a normal knee, but most frequently it slips laterally when the knee is partly flexed and there is a rotational strain on the joint. The knee gives way, and when the knee is straightened the dislocation is reduced. The medial capsule of the joint is stretched or torn and the resulting pain and tenderness are often thought to be due to a torn medial meniscus. The first occurrence is treated, after reduction, by immobilization in full extension for three weeks, followed by very intensive quadriceps drill especially to develop the wasted medialis muscle. Recurrent episodes require surgical repair.

Fractures of the patella occur frequently from direct blows to the patella and occa­sionally from muscle violence, the patella being pulled apart. The undisplaced fractures are immobilized for six weeks and in the displaced fractures fragments are either excised or sutured. The limb is fixed in plaster for six weeks and then given a very intensive course of exercises and quadriceps drill

The Hamstring Group Muscles of this group are rarely injured,

although occasionally following injury the

INJURIES ABOUT THE KNEE JOINT 23

tendons on the medial side of the joint slip over one another, giving rise to symp­toms suggestive of a torn meniscus.

Ligamentous Injuries The medial ligament is much more

frequently injured than the lateral The injury occurs when the knee is forced into valgus and is a frequent sporting injury. There may be only a straining of the ligament or a partial or complete rupture. Mild injuries are treated by the application of a supporting bandage, heat, exercises for the quadriceps and by raising the inner border of the heel of the shoe. More severe injuries require immobiliza­tion in almost full extension for three to four weeks and the most severe require surgical repair of the ligament and im­mobilization for six weeks. The meniscus is often displaced at the same time. In the severe forms of injury the anterior cruciate ligament is also often torn.

The lateral ligament is rarely injured, but when the knee is violently forced into varus the head of the fibula is pulled off and, as the biceps is also attached here, the fibular fragment is pulled well above the knee. It requires surgical replacement followed by immobilization in plaster.

The cruciate ligaments are torn only in severe injuries, usually with partial or complete dislocations of the knee. The knee is fixed in plaster with the joint flexed 300 and maintained in this position for eight to ten weeks. Quadriceps and hamstring exercises are never more im­portant than following this injury, which gives rise to antero-posterior instability of the joint. However, the pessimism expressed so often after this type of injury is not justified as quite marked instability can be adequately controlled by good muscle development. Rarely is surgical repair justified and the results are not satisfactory,

Injuries to Menisci These occur with twisting injuries of

the knee; the knee is partly flexed and at

the critical moment the patient tries to extend the leg forcibly, often splitting the meniscus in the horizontal plane* This is accompanied by sudden pain in the joint,. usually on the side of the lesion, but often the patient describes it as in the knee or under the knee cap. Swelling occurs due to effusion within one to four hours. With the so-called "bucket-handle" tear the knee may be locked, lacking 5°-io° of extension and flexion being possible only to go0.

The meniscus may tear in various situations. Each area has a rather typical history but a few general points should be made. Firstly, it is very rare for a child under 15 years of age to tear a meniscus. Secondly, it is not a common injury in women over 30 years, although pain on the inner side of the knee and swelling of the joint are not uncommon,. usually the result of nipping the infra-patellar fat pad in the joint on the medial side. A direct blow to the knee often enlarges this fat pad, making it prone to> be caught between the joint surfaces. Thirdly, unless the knee is locked, surgery is not immediately required and rest and exercises for the quadriceps are indicated. If symptoms of "giving way", "clicking" or swelling persist after a fair trial of conservative measures, operation for excision of the meniscus is the only treatment. Fourthly, direct blows on the knee do not cause a tear of a meniscus but they do cause pain and tenderness of the synovium which may be very slow to settle down. Fifthly, cystic changes follow­ing injury are common in the lateral meniscus and they also occur in the medial meniscus. These give rise to localized swellings on the joint line, pain, especially at night, and exquisite tenderness. Removal of the meniscus must be carried out.

SUMMARY The unique characteristics of the knee

joint are described and their relationship to anatomical factors and to injury are outlined. The common injuries, parti­cularly to ligaments and menisci, and their management are discussed.