Abstract
BackgroundSimultaneous motion of the knee and ankle joints is required for many activities including gait. We aimed to evaluate the influence of surgery involving tendons around the knee on ankle motion during gait in the sagittal plane in cerebral palsy patients.MethodsWe included data from 55 limbs in 34 patients with spastic cerebral palsy. Patients were followed up after undergoing only distal hamstring lengthening with or without additional rectus femoris transfer. The patients’ mean age at the time of knee surgery was 11.2 ± 4.7 years, and the mean follow-up duration was 2.2 ± 1.5 years (range, 0.9–6.0 years). Pre- and postoperative kinematic variables that were extracted from three-dimensional gait analyses were then compared to assess changes in ankle motion after knee surgery. Outcome measures included ankle dorsiflexion at initial contact, peak ankle dorsiflexion during stance, peak ankle dorsiflexion during swing, and dynamic range of motion of the ankle. Various sagittal plane knee kinematics were also measured and used to predict ankle kinematics. A linear mixed model was constructed to estimate changes in ankle motion after adjusting for multiple factors.ResultsImprovement in total range of motion of the knee resulted in improved motion of the ankle joint. We estimated that after knee surgery, ankle dorsiflexion at initial contact, peak ankle dorsiflexion during stance, peak ankle dorsiflexion during swing, and dynamic range of motion of the ankle decreased, respectively, by 0.4° (p = 0.016), 0.6° (p < 0.001), 0.2° (p = 0.038), and 0.5° (p = 0.006) per degree increase in total range of motion of the knee after either knee surgery. Furthermore, dynamic range of motion of the ankle increased by 0.4° per degree increase in postoperative peak knee flexion during swing.ConclusionsImprovement in total knee range of motion was found to be correlated with improvement in ankle kinematics after surgery involving tendons around the knee. As motion of the knee and ankle joints is cross-linked, surgeons should be aware of potential changes in the ankle joint after knee surgery.
Highlights
Simultaneous motion of the knee and ankle joints is required for many activities including gait
Patient recruitment We reviewed the medical records of patients with spastic cerebral palsy (CP) who were followed up after rectus femoris transfer (RFT) or distal hamstring lengthening (DHL), and who had undergone pre- and postoperative three-dimensional (3D) gait analysis between January 1995 and December 2015
We found that pre- and postoperative ankle dorsiflexion at initial contact, peak ankle dorsiflexion in stance, and dynamic ankle range of motion (ROM) were smaller in the DHL with RFT group than in the DHL only group (Table 3)
Summary
Simultaneous motion of the knee and ankle joints is required for many activities including gait. We aimed to evaluate the influence of surgery involving tendons around the knee on ankle motion during gait in the sagittal plane in cerebral palsy patients. Stiff-knee gait and crouch gait are among the most common gait problems in ambulatory patients with cerebral palsy (CP) [1, 2]. Knee surgery procedures such as RFT or DHL without additional ankle surgery can be considered in these patients. The resultant simultaneous motion of the knee and ankle joints is required for many activities including standing, running, swimming, and cycling [7]. Adequate coupling of plantar flexion and knee extension [8] regulates the direction and modulus of ground reaction force, which subsequently acts to optimize gait
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