Rehabilitation and Evaluation after Anterior Cruciate Ligament Injury : Function, Stability and Postural Control

Sammanfattning: Traditionally, the success of treatment after anterior cruciate ligament (ACL) injury has been judged from the recovery of muscle strength and knee range of motion (ROM), but also from the static knee stability after ACL reconstruction. However, since the sensory role of the ACL and surrounding tissues for the functional stability of the knee has been documented, the measurement of proprioceptive function related to knee stability is likely to become important in this evaluation.The main purpose of this thesis was to critically examine some generally accepted principles in the treatment after ACL injury and in the way the outcome of this treatment is judged. In addition, we introduce a dynamic posturography system in order to functionally assess the peripheral contribution to postural control in patients with a chronic ACL insufficiency and in patients after ACL reconstruction.The hypothesis tested was that dynamic measurement of anterior-posterior (AlP) laxity would be of greater value than the currently used measurement of static AlP laxity for assessing the result of ACL reconstruction and that these measurements could also be used for selection of rehabilitation exercises. We found that open kinetic chain exercises provoked larger sagittal plane translation than closed kinetic chain exercises and therefore should be avoided in early ACL rehabilitation. The present study furthermore shows that dynamic laxity measurements may be clinically useful to identify ACL injured patients, who are unable to limit the anterior translation of tibia during dynamic exercise.A prospective randomized comparison in patients after ACL reconstruction did not reveal any differences with respect to ROM, static total AlP laxity and subjective knee score and activity level between patients postoperatively treated with an early ROM training and patients treated with five weeks immobilization in plaster. On the contrary, at the 2-year follow-up, the strength deficit in the hamstring and quadriceps muscles tended to be larger in the early ROM trained than in the plaster group (p<0.05 for hamstrings and p=0.07 for quadriceps), possibly related to the greater need for involvement of the physical therapist in the plaster group.It was found that still several years after injury, non-operated ACL injured patients had a significantly greater body sway while standing on the injured limb but also on the uninjured limb on a stable surface. Furthermore, the measurements during perturbations in the sagittal plane showed a longer reaction time and a greater sway amplitude in the single-limb stance among patients than among c:ontrols, with no difference between the injured and the uninjured leg. On the other hand, following ACL reconstruction most measurements of postural control were not different in patients than in controls (36 months postoperatively). The normalization of postural control as well as in subjective knee score and activity level occurred in spite of the total sagittal laxity being significantly higher in the ACL reconstructed knee than in the uninjured knee and in the control group. However, the patients still had significantly longer reaction times for the postural responses to perturbations forwards and backwards, with no difference between the patients' ACL reconstructed and healthy leg. The impaired postural control in ACL deficient patients both while standing on the injured limb and on the uninjured limb, as well as the lack of correlation between the measured laxity of the reconstructed knee and any of the variables in perturbations provide evidence that rehabilitation with proprioceptive and agility training is an important part of the treatment to condition the dynamic restraints and thus improve the functional stability in the ACL reconstructed knee.