Objectives
In the reconstruction of the anterior cruciate ligament (ACL) painkillers is used to reduce the amount of pain. Our aim was to improve the basis for postoperative paint treatment using KOOS and the pain threshold before surgery. Further investigate the vivo metabolic changes in the skeletal muscle.

Methods
6 patients (age 19-32) with ACL lesion were included in the prospective cohort study from 19th October to 7th December 2015. The patients underwent the standard procedure for reconstruction of the ACL. Before surgery patients reported KOOS, EQ-5D-5L and PainDetect Questionnaires. Further the pain threshold and pain sensibility were investigated with a digital pressure pain threshold algometer (PPT) and the pain stimulus from a mechanic spring-clamp (MSC). MiD was used to investigate the vivo metabolic changes in the skeletal muscle tissue during the surgery and shortly after. Glucose, lactate, pyruvate and glycerol and lactate/pyruvate ratio (L/P ratio) was used as indicators of tissue ischemia.

Results
In four of the five KOOS subscales the ACL lesion patients scored significantly worse compared to the ref-erence population. EQ-5D-5L showed xx. PD-Q preoperative showed that the pain was nociceptive pain.
Preoperatively patients reported high pressure point threshold (PPT) and there were none significant differ-ence before and after applying the pain stimulus.
Microdialysis showed highly increase of the concentration of glycerol and L/P-ratio (lactate/pyruvate-ratio) during the operation.

Discussion
With our results from KOOS, pain threshold and microdialysis, there is a basis for an improvement the pain management. There are still many aspects that needed to be investigated before we can make a definitive conclusion.
Key words ACL reconstruction, microdialysis, pain threshold, KOOS, EQ-5D, PainDetect