This test checks ligament laxity at 90 degrees. It must be realised that it is possible to have an anterior cruciate ligament tear without an anterior draw being present. It is folly to exclude an anterior cruciate ligament tear based on lack of anterior draw. The test is particularly controversial and consists of three parts.

With the knee flexed at 90 degrees, the examiner sits onto the patient’s toes and, after testing for hamstring relaxation, applies a straight draw.

Slight anteromedial movement may occur if there has been a tear of the meniscotibial ligament.

A straight draw may be elicited where both tibial condyles move anteriorly and equally on the femoral condyles. The anticipated pathology is a torn anterior cruciate ligament with laxity in the medial and lateral capsules and collateral ligaments. This represents a combined rotatory instability: anteromedial and anterolateral.

The examiner sits onto the patient’s externally rotated foot, thus tightening the medial structures, and applies an anterior draw . If there is a tear in the medial compartment ligaments, the medial tibial condyle will sublux anteriorly and rotate externally; this will be accentuated by an anterior cruciate ligament tear, indicating anteromedial rotatory instability.

The examiner sits onto the patient’s internally rotated foot, thus tightening the lateral structures, and applies an anterior draw. If the lateral tibial condyle moves forwards on the femur, a tear of the lateral complex should be suspected.

In this test both knees are at 90 degrees flexion, with the examiner’s hand holding the feet. The tibial positions should be compared, looking for a posterior sag.

Each knee is then examined at 90 degrees flexion with the foot fixed, applying a direct posterior draw.

Both these tests, if positive, indicate a posterior cruciate ligament rupture. A common error is to mistake a knee ‘sitting’ in posterior draw as being in neutral and thus, when found lax to anterior force, to regard that laxity as an anterior draw. Close observation for a posterior sag will distinguish this.

If properly performed, this test is very reliable for anterior cruciate ligament laxity. The knee is brought to 15 degrees flexion and an anterior draw is applied.

The draw is assessed for the feeling of an endpoint and compared to the other knee. Lack of a definite endpoint or marked increased draw in comparison with the opposite side is evidence of anterior cruciate ligament damage. This test is difficult for the inexperienced examiner, and for those with small hands. Posterior subluxation will also need to be excluded (check for posterior sag).

This test is also used for diagnosing an anterior cruciate ligament rupture. It is a dynamic Lachman test, performed by the quadriceps musculature.

With the patient supine, the knee is extended on the examination table and a closed fist is placed distally under the femur in complete relaxation. The patient is then asked to raise the leg; as the quadriceps contracts the tibia is seen to move anteriorly on the femur.

The leg is then placed back on the examiner’s fist and relaxed with relaxation the tibia drops posteriorly onto the femur to its resting neutral position.

This test can be particularly helpful in the acute knee injury, where some of the more complex tests may be difficult. It is also ideal for the inexperienced examiner, in assessing anterior cruciate ligament integrity.