Anterior cruciate ligament (ACL) injuries are common in adults and cause knee instability, pain, and an increased risk of osteoarthritis. Previous studies demonstrated changed gait patterns in adult patients with ACL deficiency. In paediatric patients, ACL injuries were once thought to be rare but are being increasingly diagnosed due to greater involvement of children in contact sports and to the introduction of more effective diagnostic tools such as magnetic resonance imaging (MRI). However, little is known about gait adaptation in children with ACL deficiency. The objective of this study was to look for compensatory foot and ankle behaviours during gait in paediatric patients with symptomatic ACL deficiency.

Compensation for ACL deficiency during gait occurs at the foot and ankle in children, because compensation at the hip and pelvis would require greater energy expenditure.

We included 47 patients, 33 males and 14 females, ranging in age from 9 to 17 years (mean, 14.1 years). The patients had a history of unilateral ACL injury documented by MRI and initially treated by immobilisation and physical therapy. They were allowed to walk with full weight-bearing on the affected limb and were not taking medications at the time of the study. All patients had pain, knee instability, or functional limitation. The physical examination showed joint laxity indicating surgical ACL reconstruction. None had neurological conditions, congenital musculoskeletal abnormalities, or a history of knee surgery. Gait analysis (GA) was performed using a Vicon 460 system. Kinematic data for the ankle and foot were compared to those in a control group of 37 healthy children. Ankle angular positions were calculated for each group at the following stance time points: initial contact (0% of gait cycle [GC]), mid-stance (25% GC), terminal stance (60% GC), and swing (83% GC). Foot progression data were recorded at mid-stance (25% GC) and swing (70% GC). Student's t test was applied to compare the results to reference values obtained at our laboratory and to data from the control group.

Compared to the reference values, the ankle was in plantar flexion at initial contact in 41 patients, and ankle dorsiflexion during the stance phase was diminished in 39 patients. The external foot progression angle was increased in 23 patients during the stance phase and 38 patients during the swing phase. Compared to the control group (mean age, 9.1 years), the patients had plantar flexion of the ankle at initial contact (3.43°±3.5° vs. 0.74°±3.6°, p<0.05) and decreased dorsiflexion during the stance phase (3.43°±3.5° vs. 0.74°±3.6°, p<0.05). No significant differences were found for any of the other parameters.

Children with ACL deficiency developed compensatory foot and ankle behaviours during gait that improved knee stability. Understanding these compensations may guide treatment optimisation.

III, retrospective comparative study.