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

Are there differences in muscle strength in individuals with spastic diplegic with/without a history of selective dorsal rhizotomy

Shriners Hospitals for Children, Portland, OR, USA

Objective: To determine if selective dorsal rhizotomy (SDR) has a long-term impact on muscle strength in ambulatory individuals with spastic diplegia.

Design: Prospective cohort.

Setting: Outpatient clinics at a chidlren’s hospital.

Participants: Eight individuals > 5 years post SDR (mean age 15y 3mo; Gross Motor Function Classification System [GMFCS] Levels I and II) and eight matched individuals with spastic diplegia (SpD; mean age 14y3mo) were recruited.

Method: Muscle strength (concentric, isometric, eccentric) of the extensors and flexors of the elbow, knee, and ankle were assessed using a Biodex System 3 Pro isokinetic dynamometer. Individuals were assessed at baseline, 3, and 6 months. At 6 months a 6-week home program for muscle strengthening was implemented. Muscle strength was reassessed following the home program and at 1-year post-baseline. The first three assessments were combined to form the baseline for analysis. Repeated measure analyses of variance and linear contrasts (p<0.05) were used to determine differences between the groups.


Elbow: The SDR group demonstrated significantly greater concentric strength (60, 120 0/s; p<_0.001) than the SD group at all assessments times. Isometric (45, 1000 0) and eccentric strength (45 0/s) were greater in the SDR group, but not consistently significant.

Knee: The SDR group was significantly stronger than the SD group in concentric strength at baseline (30, 60, 120 0/s; p<_0.04); however, at the 1-year follow-up the SD group demonstrated concentric strength comparable to the SDR group at the slower speeds of movement (30, 60 o/s). The SDR group demonstrated consistently greater isometric strength than the SpD group at all assessments; however differences were only significant for isometric flexion (30, 60, 90 o; p<_0.001). Eccentric strength (45 o/s) was comparable between the groups.

Ankle: Although not significant, the SDR group tended to demonstrate greater concentric (30, 60 0/s) dorsiflexor strength than the SpD group, while the SpD group demonstrated greater concentric plantarflexor strength. In isometric strength ( 5 o dorsiflexion, 10 0 plantarflexion) this trend was reversed with the SDR group demonstrating greater planatarflexor  strength than the SpD group, while the SpD group demonstrated greater dorsiflexor strength. Reliability of concentric and eccentric ankle strength testing on the Biodex was questionable ude to limited motor control in study individuals and the mass of the Biodex footplate.

Conclusions: Individuals with a long-tem history of SDR did not demonstrate grater muscle weakness, most significantly about the knee, compared with a matched group of individuals without a history of SDR. Subtle differences between individuals with/without a history of SDR were noted in this study; however, conclusions are limited due to the small sample size and the known heterogeneity of this population, despite the matching of GMFCS levels.

Acknowledgements: Shriners Hospitals for Children, grant no. 8630.

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