The impact of hamstring lengthening on stance knee flexion at skeletal maturity in ambulatory cerebral palsy.

This study reports the long-term outcomes of hamstring lengthening to treat flexed knee gait in children with ambulatory cerebral palsy (CP) after skeletal maturity. This retrospective longitudinal observational study used instrumented gait analysis (GA) <8 and >15 years old in children with bilateral CP. The primary variable was knee flexion in stance phase. Eighty children (160 limbs) were included; 49% were male, 51% female. Mean age at first GA was 6.0 (SD: 1.2) years and 19.6 (SD: 4.5) years at final GA. Mean follow-up was 13.7 (SD: 4.7) years. Children were classified as Gross Motor Function Classification System I-8, II-46 and III-26. Average Gross Motor Function Measure Dimension D was 72% (SD: 20%). Hamstring lengthenings occurred once in 82, twice in 54 and three times in 10 limbs. From initial to final GA, average knee flexion in stance was unchanged, 27.8° (SD: 14.8°) to final 27.0° (SD: 11.2°; P = 0.54). Knee flexion at foot contact was 39.6° (SD: 13.0°), improving to final GA of 30.7° (SD: 10.6°; P < 0.001). Initial gait deviation index was 65.8 (SD: 31.9), improving to final 78.9 (SD: 28.2; P < 0.001). Older age, males and concomitant plantar flexor lengthening predicted change toward more flexed knee gait. Hamstring lengthening did not lead to back-kneeing gait at maturity while maintaining childhood stance phase knee flexion. A subgroup still developed significant flexed knee gait posture and may have benefited from more aggressive treatment options. This outcome may also be impacted by diverse functional levels, etiologies and treatments of flexed knee gait.

Factors influencing post-surgical variability in StepWatch data in youth with cerebral palsy.

BACKGROUND: Over the past several years, activity monitors have become very popular in the general population, and due to their low cost and ease of use, are starting to be seen as clinical tools for the assessment of interventions. This presents researchers with the opportunity to better understand how activity, or lack thereof, is related to the recovery of patients. However, even in individuals without disabilities, there is a high degree of variability in activity monitor data which must be better understood in order to produce clinically meaningful interpretation of such data. RESEARCH QUESTION: What sources of variability contribute the most to the daily scatter in activity data as measured by StepWatches in youth with Cerebral Palsy (CP)? In particular, do non-clinical factors such as weather and location contribute to this variability significantly? METHODS: This was a retrospective study making use of data from our activity monitoring protocol of youths with CP who obtain single event multi-level surgeries. Before and after these surgeries, 57 such youths aged 4.2-21.3 years were issued StepWatches to monitor daily activity for 8 day periods over 24 months duration. Weather data and walk scores for the patients' home locations were collected from online databases. Steps per hour were predicted from clinical and environmental data using bootstrapped regression to determine the stability of regression coefficients and the percent variability explained by each variable. RESULTS: Time since surgery, age, season, GMFCS level, and surgical burden were significant variables in the model. Of them, GMFCS level was most important and explained nearly 16% of the variability in the data. Temperature, precipitation, and walk score had small effects on step count variance. SIGNIFICANCE: Understanding sources of variability in step-counts is important if such a measure is to be used as a clinical measure of recovery, and may be important in the consideration of future surgical planning.

Concurrent surgeries are a factor in predicting success of rectus transfer outcomes.

Cerebral palsy (CP) patients exhibit a wide range of functional responses to specific surgical interventions. The variability associated with surgical outcomes within this patient population precipitates the need to determine the functional effects in advance of the surgery. Pilot studies have indicated that the application of statistical models towards predicting functional outcomes of surgery produces clinically meaningful results. The purpose of this study was to evaluate the influence of pre-operative kinematic parameters in conjunction with concurrent surgeries on rectus transfer (RT) outcomes. Gait analysis data were collected from 68 patients (94 legs) pre- and post-operatively within a year of surgery. Patients were divided into four groups. Group 1 (N=14) contained only legs experiencing a rectus transfer. Group 2 (N=30) contained legs experiencing RT and hamstring lengthening (HL). Group 3 (N=7) contained legs experiencing RT and lower leg surgeries: either Achilles lengthening (AL), or gastrocnemius lengthening (GL). Finally, Group 4 (N=43) contained legs which experienced all four surgeries (RT+HL+AL+GL) concurrently. Multivariate jackknifed linear regression was used to predict the change in knee range of motion, DeltaROM, due to surgery on a group-by-group basis. In each case, the sole significant pre-surgical variable was the range of motion. Group 1 legs had the best correlation (R=0.846) between pre-surgical ROM and DeltaROM whereas Group 4 legs had the worst correlation (R=0.661). Group 3 results were not significant. Group 1 DeltaROM were also significantly lower as a whole, than all other groups, due to a larger percentage of patients needing the surgery to change timing of flexion in swing phase. When compared to modeling without consideration of surgery, modeling by surgical group produced results with fewer outliers and better correlation coefficients. Regardless of surgical group, patients with a lower pre-surgical ROM (<40 degrees ) were more likely to experience an increase in ROM as a result of surgical intervention compared to their peers with an elevated pre-surgical ROM who were likely to see a decrease in ROM. Pre-surgical ROM therefore serves as a useful predictor of outcome in rectus transfer surgery.