Fig. 106 Varus stress test
SYMPTOMS The symptoms are immediate haemarthrosis and pain in the lateral part of the knee. This injury is common in contact sports such as football, rugby and other high-intensity sports. LCL ruptures occur during a varus sprain and cause an inability to continue sport. The forces involved are high; since the lateral knee structures are stronger than the medial, these injuries are rare.
AETIOLOGY The ligament can rupture either partially (Grade I-II) or completely (Grade III-IV). Note! This injury is often associated with injuries to either the ACL, PCL, cartilage, menisci, capsule or the posterior lateral corner.
CLINICAL FINDINGS There is haemarthrosis in most cases. If there is a capsule rupture, blood can penetrate from the joint and cause bruising around the lateral part of the knee. The varus stress test is positive if the rupture is complete. This is the most sensitive test and can verify a lateral ligament rupture in most cases. The test should be done with a straight knee, which will show positive if there is a complete rupture, and with the knee flexed at 20-25 degrees. If the latter test is positive, this should raise suspicion of injury to the posterior lateral corner where the popliteus tendon is the predominant stabiliser. Dyer's test is valuable to evaluate the laxity caused by ruptures at the posterior lateral corner and this is indicated by an increased external rotation of the foot. Since there are often associated injuries, examination must also include tests for cruciate ligaments, menisci and cartilage.
INVESTIGATIONS Clinical examination is the most important tool for diagnosis and should include tests for all ligaments and other structures in the knee. X-ray is valuable to rule out fractures, in particular in growing or elderly athletes. MRI can verify the LCL tear in most cases but is also important for evaluating associated injuries.
TREATMENT An athlete with haemarthrosis and suspected LCL tear should be seen by an orthopaedic surgeon to consider MRI or arthroscopy. This procedure can verify the diagnosis and deal with associated injuries that are often missed. Grade I-II injuries are treated non-operatively but Grade III-IV may need surgery. Posterior lateral corner injuries are very difficult to treat and should be referred to a knee specialist. A brace is often recommended. REFERRALS Refer to orthopaedic surgeon early for further investigations to verify the extent of the injury. Physiotherapists will be involved in close collaboration with the surgeon. EXERCISE PRESCRIPTION Cycling and swimming are good alternatives to keep up general fitness. Varus stress to the knee should be avoided so breast stroke is not recommended. Rehabilitation back to full sport usually takes around six months.
Monitor clinical symptoms and signs. Different functional knee scores for different sports are available to measure when the knee allows a return to full sport.
DIFFERENTIAL DIAGNOSES This is a difficult diagnosis and associated injuries to the capsule, menisci, cartilage or cruciate ligaments and fractures should always be borne in mind. PROGNOSIS Appropriate treatment may allow a return to professional sport within six months. Some of these injuries are career-threatening for professional athletes.
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