Purpose: To determine if it is necessary to assess instability of the chronic anterior cruciate ligament deficient knee under general anaesthesia.

Materials and methods: 27 anterior cruciate ligament deficient knees in 27 patients were evaluated both subjectively using the Lachmanns and pivot shift test and objectively using the KT 1000 arthometer. This was done in the preoperative clinic (without the patient anaesthetised) and subsequently in the anaesthetic room with the patient anaesthetised (under general anaesthesia) prior to anterior cruciate ligament reconstruction. The data was prospectively collected. Only data on 21 knees was available for analysis. There were 20 females and one male with an average age of 29 years.

Results: There was no statistical significant difference (using students T test) between the data collected using the KT 1000 arthometer with and without the patient anaesthetised.

A significant difference was noted both for the Lachmanns (p< 0.01) and pivot shift test (p< 0.001) between the results obtained with and without anaesthesia. This however did not change the management.

Conclusion: Assessing the chronic anterior cruciate ligament deficient knee using the KT 1000 arthrometer, Lachmann and pivot shift test under general anaesthesia is not necessary if these assessments have been carried out in clinic.