Influence of gait analysis on decision-marketing for lower extremity surgery

Assessment of possible rectus femoris transfer outcome predictors in patients with cerebral palsy and stiff knee gait


  1. 1.Children’s Memorial Hospital Motion, Analysis Center, Chicago, II, USA

Background/Objective: Stiff knee gait (SKG) is a condition commonly seen in children with cerebral palsy  (CP). A common surgery to alleviate SKG is a rectus femoris transfer (RFT) which aims to reduce the rectus femoris’ hip flexor/knee extensor capacity. The specific aim of this study was to evaluate four SKG parameters (SKGP) established by previous studies in children with CP. We hypothesized that children with CP and SKG who received a lateral RFT would show improved post-op SKGP, knee angular velocity (KAV), and knee extension moments (KEM).

Design: Retrospective cohort study.

Study Participants/Setting: Pediatric acute care hospital. Eight children with spastic diplegia CP (three females, five males, 11 legs, mean age 12y 7mo) meeting the following criteria: ambulatory without external support, received a pre- and postoperative gait analysis within 2 years of a RFT (three knees received concomitant hamstring lengthenings).

Materials/Methods: Using three-dimensional motion analysis, peak knee flexion, knee flexion range of motion (ROM) from toe-off to peak knee flexion, total knee flexion ROM, timing of peak knee flexion during the swing phase, KAV and the average KEM during double support was measured as described by Coldberg et al. SKG was defined as three out of four SKGP beyond two SDs from normal. Patient’s preoperative SKGP were analyzed. Two legs were determined as not stiff preoperative and are not presented. Postoperative outcomes were classified as: (1) no improvement; (2) some improvement ; and (3) improvement to within 2 SDs from normal. Correlations between outcome classification and preoperative SKGP, KAV, and KEM were analyzed using Spearman’s rho and Kendall’s tau-b.

Results: Pre- and postoperative SKGP are presented in Table Sp-36. Sixty-six percent improved their SKG post-op with 22% improving to normal. All knees had a low pre-op KAV with 33% improving to normal post-op. Twenty-two percent had high knee extension moments preoperatively, both improving to normal postoperatively. None of the correlations between outcome and preoperative SKGP were found to be significant due to the low sample size.

Conclusions: This study suggests that there may not be a clear trend between improved post-op SKGP and improvements in post-op KAV and KEM. SKGP may improve classification of SKG. Participants who met three out of four SKGP tended to show a favorable outcome. Increased sample size may allow us to significantly correlate outcomes to the described kinematic/kinetic variables.


  1. 1. Goldberg SR, Ounpuu S, Arnold AS, Gage JR, Delp SL. (2006)
    Kinematic and kinetic factors that correlate with improved knee flexion following treatment for stiff-knee gait. J Biomech. 39:689-698.
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