Arthrofibrosis following ACL reconstruction prevents the patient from regaining full knee movement postoperatively.

Our aim was to determine whether acute reconstruction (performed within 3 weeks of injury) is associated with an increased risk of arthrofibrosis compared with chronic reconstruction (performed more than 8 weeks after injury).

We performed a prospective study of 114 patients who underwent a patellar tendon ACL reconstruction: 62 patients underwent acute reconstruction and 52 patients underwent chronic reconstruction. All patients were operated on by a single surgeon using a standardised arthroscopic technique and accelerated rehabilitation programme. All patients were assessed independently by an experienced physiotherapist at an average of 7 months post-operatively. Range of motion, stability, muscle strength and functional scores were measured.

There was no significant difference in the incidence of arthrofibrosis between the acute and chronic groups. Flexion of less than 125° or a loss of extension of more than 10° occurred in 8 (12.9%) of the acute group and in 9 (17.3%) of the chronic group.

All knees were clinically stable, but the mean KT1000 difference was 1.21mm in the acute group and 1.89mm in the chronic group (p< 0.05). There were no significant differences in muscle strength or functional scores between the two groups.

There were significantly more meniscal injuries (65% versus 31%) and chondral lesions (31% versus 18%) in the chronic group.

Acute ACL reconstruction is not associated with an increased risk of arthrofibrosis. However, it is associated with increased stability and less meniscal and chondral pathology. This study suggests that the optimum time for ACL reconstruction is within the first 3 weeks after injury.