Evidence of knee extensor dysfunction during sit-to-stand following distal femoral extension osteotomy and patellar tendon advancement in young adults with cerebral palsy: A pilot study

Elizabeth R. Boyer, Jean L. Stout, Jennifer C. Laine, Sarah M. Gutknecht, Lucas Henrique Oliveira, Meghan E. Munger, Michael H. Schwartz, Tom F. Novacheck

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

A distal femoral extension osteotomy with patellar tendon advancement (DFEO + PTA) is a common treatment for individuals with cerebral palsy (CP) who walk in crouch. Musculoskeletal modeling suggests that the typical patella baja position post-DFEO + PTA may limit one's abilities to perform sit-to-stand (STS) tasks; however, STS function has not been assessed. Our purpose was to compare how well individuals who received a DFEO + PTA can perform a 5-times STS test (FTSST) eight or more years after surgery compared to their peers who did not receive a DFEO + PTA (non-DFEO + PTA group). Twenty-one participants completed the task (12 DFEO + PTA, 9 non-DFEO + PTA). Three-dimensional kinematics and kinetics were captured. Kinetics were non-dimensionalized to facilitate group comparisons. Non-DFEO + PTA participants performed the FTSST moderately faster than the DFEO + PTA group (median(IQR), 14.6(9.3) seconds vs. 20.3(10.1) seconds, non-parametric effect size ɣ = 0.97, p = 0.241). Peak negative knee power was larger for the non-DFEO + PTA group (Mean ± SD, −0.063 ± 0.025 vs. −0.048± 0.020, Cohen's d = 0.66, p = 0.165). A similar but weaker trend was observed for negative hip power (median(IQR) −0.120(0.066) vs. −0.105(0.044), ɣ = 0.43, p = 0.671). Both groups used their hips approximately twice as much as their knees to perform the task. The functional deficit among DFEO + PTA participants may be due to patella baja decreasing the knee extensor moment arm, which concurs with the modeling prediction. The group differences may also be due to the non-DFEO + PTA group being slightly higher functioning. Future research is warranted to determine if optimizing patella position during a DFEO + PTA may improve unaided STS function without compromising gait improvements.

Original languageEnglish (US)
Pages (from-to)527-532
Number of pages6
JournalGait and Posture
Volume58
DOIs
StatePublished - Oct 2017

Keywords

  • 5-times sit-to-stand test
  • Crouch gait
  • Distal femoral extension osteotomy
  • Flexed-knee gait
  • Patella baja
  • Patellar tendon advancement

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