Evaluation of knee joint stability after ACL reconstruction with an ST/GR graft using an Aircast Rolimeter

Introduction
ACL damage results in instability of the knee joint. It is characterized by abnormal hypermobility leading to repeated injuries of the joint.

Aim of the research
To evaluate the function of the knee joint in relation to mechanical stability and to evaluate the parameters influencing the stability of the knee joint in the period of 3 to 5 years after surgery.

Material and methods
The study enrolled 51 patients, 38 men and 13 women, operated on due to ACL rupture. The knee joint stability was assessed with a Rolimeter and the Lysholm scale, and the isokinetic muscle strength was measured with a Biodex 4 dynamometer. The study was carried out in the period from 3 to 5 years after the operation.

Results
The difference between the Rolimeter measurement of the uninvolved knee and operated one was no more than 3 mm in most of the respondents (84.3%). Joint instability over 3 mm was observed in 15.7% of the respondents. The strength of the extensor muscles of the knee joint was significantly higher in the uninvolved limbs compared to the operated ones.

Conclusions
After ACL reconstruction, some patients have instability in the operated joint. Assessment of the function and instability of the knee joint using the subjective Lysholm scale is comparable to the assessment performed with the objective research tool - the Rolimeter. Patients after arthroscopic ACL reconstruction develop chronic muscle strength disorders.