DIAGNOSIS

response to the injury. Early restoration of flexion and good gait is also important.

Only in the unusual situation that pain from a tense haemarthrosis is notable is aspiration of the joint indicated. Aspiration of blood can help confirm the diagnosis, but in view of the clinical assessment above it really is not justifiable as a diagnostic tool.

Apart from bony avulsions of ACL attachment, there is only one absolute indication for early surgery in cases of isolated ACL tears. This is fixed flexion of the joint, which can be related to a locked bucket handle tear of a meniscus, or, more commonly, an impinging stump of the torn ACL. In all other cases I can see no justification for an arthroscopy. It is surprisingly common that patients who have a classic history and examination, an ACL tear on MRI scan, and have achieved full extension still have an arthroscopy, at which little of therapeutic value is done. Then, at a later stage a second operation, an ACL reconstruction, is undertaken. I simply cannot understand the need for the first arthroscopy.

Nevertheless, if the knee will not straighten then this does represent a significant problem and an arthroscopy, either to remove the impinging ACL stump, or to deal with the bucket handle tear of the meniscus is appropriate. An early MRI scan is of use in determining the cause of fixed flexion. If the knee fully straightens, then the value of an early MRI scan becomes much less clear.

If there is significant disruption to the medial collateral ligament with excess laxity, then this should be treated with bracing in the vast majority of cases. My usual regime is 30-600

for two weeks, KEY POINTS

Acute management ■ Early focus must be on restoration of full extension and reducing the inflammatory response

■ Aspiration of the joint is rarely indicated for the unusual situation of severe pain from a tense haemarthrosis

■ Apart from bony avulsions of the ACL attachment, a fixed flexion is the only one absolute indication for early surgery

■ Fixed flexion may be caused by a locked bucket handle tear of a meniscus or an impinging stump of the torn ACL - arthroscopy is indicated to remove the stump or deal with the bucket handle tear

■ An early MRI scan is of use in determining the cause of the fixed flexion - if the knee fully straightens, the value of an early MRI is less clear

■ Significant disruption to the medial collateral ligament with excess laxity should be treated with bracing (in most cases). A suggested regime is: - 30-60O - 10-90O

for weeks 0-2 for weeks 2-4

- Free range brace for weeks 4-6

■ Repeated assessment is required to prevent the development of a fixed flexion deformity.

Management ■ An isolated ACL rupture affects joint motion laterally

more stress on the medial meniscus attrition possible medial meniscal tear more instability over- loading of medial meniscal joint surfaces medial OA increase in instability

■ Early reports suggesting that ACL reconstruction caused increased risk of OA is becoming increasingly disproved

■ Non surgical management relies on enhancement of neuro- muscular control of the knee - remaining proprioception must be maximised

■ Braces have two functions of enhancing stability: 1) To provide passive restraint to abnormal movement - effective in varus/valgus, less so against anterior/ posterior, poor in restricting rotational movements 2) Compress soft tissues and skin around the knee creating more proprioceptive input which can aid in fine tuning muscular control.

■ The author’s belief is that the risks of leaving knees ACL deficient is greater than that of well carried out surgery

■ Those left without ACLs need to acknowledge that they will continue to be vulnerable.

8 sportex medicine 2007:33(Jul):6-9 followed by 10-900 for two weeks and then free range in a brace for

a further two weeks. The patient needs repeated reassessment to help prevent them developing a fixed flexion deformity. If they seem to be stiffening up rapidly I will allow earlier restoration of full extension than the regime quoted. After bracing, should excessive MCL laxity be present it is much less than the original presentation and surgical reconstruction much more minor than it would have been. In more severe, but rare, injuries, in which the MCL has completely torn off its bony attachment, and the fibres can be seen curled up on MRI scanning, and the meniscus displaced out of the joint, then repair of the ruptured collateral ligament should be undertaken within the first two to three weeks from injury. The same goes for a significant disruption of the postero-lateral corner structures.

THE NATURAL HISTORY OF ACL RUPTURE Previously, and indeed for a long time, it was thought that the majority of patients did not require surgical reconstruction of a ligament. The so called 'rule of thirds' was often applied. It was thought that one third of patients would do very well without an ACL, another third could cope by adapting their lifestyles, and the other third would require surgery. This is now understood to be completely wrong. A minority of patients can genuinely cope well without an ACL; they tend to have much lower demand activity levels. Unfortunately most of those who initially think they cope well without their ACL tend to realise later that they require surgery. The reality is that most patients are unlikely to return to the same level of activity as they undertook prior to ACL rupture, and if they do it will be unlikely to be sustained, and is likely to be at the price of further damage to the joint structures.

An isolated ACL rupture affects joint motion laterally. Medial joint