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

Rectus femoris transfer in children with cerebral palsy: evaluation of transfer site and preoperative indicators

K MUTHUSAMY MRCS A, AJ SEIDL BS A, R M FRIESEN BA A,
| P ZHAOXING PHD B, JJ CAROLLO PHD PE A, F M CHANG MD A

  1. 1. Center for Gait and Movement Analysis (CGMA), The Children’s Hospital Denver, CO;
  2. 2. Research Institute, The  Children’s Hospital Denver, CO, USA

Objectives: Introduce knee flexion angular velocity as a predictor of surgical outcome, Investigate the effect of different transfer sites on the overall success, and test the validity of commonly used preoperative indicators.

Design: Retrospective intervention study.

Participants: A consecutive series of 38 children (70 legs), with cerebral palsy (CP) who underwent a rectus femoris transfer (RFT) and pre- and postoperative gait analyses.

Setting: Instrumented gait analysis laboratory.

Methods: Knee flexion angular velocity was defined as the change in degrees per second from opposite foot initial contact to peak knee flexion in swing (PKFSW) calculated using the following formula:

Degree of PKFSW – Degree of flexion at opposite Limb initial contact
Time of PKFSW -     Time at opposite limb initial contact

Patients were divided by transfer site: Semitendinosus, sartorius, or gracilis. Five knee kinematic variables were evaluated. Duncan-Ely test, electromyography (EMG) firing pattern, age, and number of concomitant procedures were evaluated for correlation with surgical outcome.  Results: A significant improvement (p<0.05) was observed in the angular velocity of the knee curve during initial swing postoperatively. Receiver operating characteristic analysis showed that patients with a baseline angular velocity of <_160 0/s had the most favorable outcome with 81.1% improving postoperatively. The extent of change was inversely proportional to the preoperative value.

For all patients, significant (p<0.05) improvements in kinematics were found in three of the outcome variables. Patients had a significant improvement in postoperative knee range of motion (KROM) when the preoperative KROM was <80% of normal. EMG pattern and Duncan-Ely test were not found to be useful indicators of surgical success. Peak knee flexion at loading response was the only variable found to improve significantly with age.

Conclusions: Preoperative knee flexion angular velocity and KROM were found to be useful predictors of surgical outcome, while other commonly used indicators such as EMG pattern and Duncan-Ely test were not. The technique used to calculate angular velocity using distinct gait events is easily reproducible in a clinical setting and eliminates the need to classify different knee flexion wave shapes. The authors recommend RFT surgery in children with CP who exhibit a stiff-knee gait, regardless of transfer site or age.

 
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