Biomechanical and Clinical Correlates of Stance-Phase Knee Flexion in Persons With Spastic Cerebral Palsy.

To identify biomechanical and clinical parameters that influence knee flexion (KF) angle at initial contact (IC) and during single limb stance phase of gait in children with spastic cerebral palsy (CP) who walk with flexed-knee gait. Retrospective analysis of gait kinematics and clinical data collected from 2010-2013. Motion & Gait Analysis Laboratory at Lucile Packard Children's Hospital, Stanford, CA. Gait analysis data from persons with spastic CP (Gross Motor Function Classification System [GMFCS] I-III) who had no prior surgery were analyzed. Participants exhibiting KF ≥20° at IC were included; the more-involved limb was analyzed. Outcome measures were analyzed with respect to clinical findings, including passive range of motion, Selective Motor Control Assessment for the Lower Extremity (SCALE), gait kinematics, and musculoskeletal models of muscle-tendon lengths during gait. KF at IC (KFIC) and minimum KF during single-limb support (KFSLS) were investigated. Thirty-four participants met the inclusion criteria, and their data were analyzed (20 males and 14 females, mean age 10.1 years, range 5-20 years). Mean KFIC was 34.4 ± 8.4 degrees and correlated with lower SCALE score (ρ = -0.530, P = .004), later peak KF during swing (ρ = 0.614, P < .001), and shorter maximal muscle length of the semimembranosus (ρ = -0.359, P = .037). Mean KFSLS was 18.7 ± 14.9 and correlated to KF contracture (ρ = 0.605, P < .001) and shorter maximal muscle length of the semimembranosus (ρ = -0.572, P < .001) and medial gastrocnemius (ρ = -0.386, P = .024). GMFCS correlated more strongly to KFIC (ρ = 0.502, P = .002) than to KFSLS (ρ = 0.371, P = .031). Linear regression found that both the SCALE score (P = .001) and delayed timing of peak KF during swing (P = .001) independently predicted KFIC. KF contracture (P = .026) and maximal length of the semimembranosus (P = .043) independently predicted KFSLS. Correlates of KFIC differed from those for KFSLS and suggest that impaired selective motor control and later timing of swing-phase KF influence knee position at IC, whereas KF contracture and muscle lengths influence minimal KF in single-limb support, findings with important treatment implications.

Rha DW ，Cahill-Rowley K ，Young J ，Torburn L ，Stephenson K ，Rose J ... -  《-》

Biomechanical and clinical correlates of swing-phase knee flexion in individuals with spastic cerebral palsy who walk with flexed-knee gait.

To identify clinical and biomechanical parameters that influence swing-phase knee flexion and contribute to stiff-knee gait in individuals with spastic cerebral palsy (CP) and flexed-knee gait. Retrospective analysis of clinical data and gait kinematics collected from 2010 to 2013. Motion and gait analysis laboratory at a children's hospital. Individuals with spastic CP (N=34; 20 boys, 14 girls; mean age ± SD, 10.1±4.1y [range, 5-20y]; Gross Motor Function Classification System I-III) who walked with flexed-knee gait ≥20° at initial contact and had no prior surgery were included; the more-involved limb was analyzed. Not applicable. The magnitude and timing of peak knee flexion (PKF) during swing were analyzed with respect to clinical data, including passive range of motion and Selective Control Assessment of the Lower Extremity, and biomechanical data, including joint kinematics and hamstring, rectus femoris, and gastrocnemius muscle-tendon length during gait. Data from participants demonstrated that achieving a higher magnitude of PKF during swing correlated with a higher maximum knee flexion velocity in swing (ρ=.582, P<0.001) and a longer maximum length of the rectus femoris (ρ=.491, P=.003). In contrast, attaining earlier timing of PKF during swing correlated with a higher knee flexion velocity at toe-off (ρ=-.576, P<.001), a longer maximum length of the gastrocnemius (ρ=-.355, P=.039), and a greater peak knee extension during single-limb support phase (ρ=-.354, P=.040). Results indicate that the magnitude and timing of PKF during swing were independent, and their biomechanical correlates differed, suggesting important treatment implications for both stiff-knee and flexed-knee gait.

Rha DW ，Cahill-Rowley K ，Young J ，Torburn L ，Stephenson K ，Rose J ... -  《-》

Dynamic spasticity determines hamstring length and knee flexion angle during gait in children with spastic cerebral palsy.

Previous researchers reported that popliteal angle did not correlate well with knee angle during gait in individuals with spastic cerebral palsy (CP). To determine if hamstring spasticity, as measured by Modified Tardieu Scale (MTS) at rest, is associated with knee flexion angle at initial contact and midstance during gait. Thirty ambulatory children (mean age 8.7 ± 2.4 years) diagnosed with spastic CP participated. The hamstrings' spasticity was assessed in the supine position with the MTS, measuring R1 (muscle reaction to passive fast stretch), R2 (passive range of motion), and R2-R1 (dynamic component of spasticity). We conducted 3-dimensional computerized gait analysis and calculated semimembranosus muscle-tendon length and lengthening velocity during gait using musculoskeletal modeling and inverse kinematic analysis by OpenSim. Pearson correlation coefficients were calculated to estimate the association of MTS with biomechanical parameters during gait. Knee flexion angle at initial contact and maximal knee extension angle during stance phase significantly positively correlated with both R1 and ㅣR2 - R1ㅣ of MTS, but not with R2 angle. The length of semimembranosus at initial contact, end of swing, and minimal length during stance phase were strongly negatively associated with R1, rather than R2 or ㅣR2 - R1ㅣ angles. The R1 angle of MTS (muscle reaction to passive fast stretch) is more relevant correlate of knee flexion angle during gait than the R2 (passive range of motion).

Choi JY ，Park ES ，Park D ，Rha DW ... -  《-》

Rectus femoris transfer in cerebral palsy patients with stiff knee gait.

Although several studies have reported on the outcomes of rectus femoris transfer (RFT), few have investigated the multiple factors that could affect the results. Therefore, we evaluated the outcomes of RFT and analyzed factors that influence improvement and annual change in knee motion after surgery in patients with cerebral palsy (CP). We reviewed ambulatory patients with CP who were followed up after they had undergone RFT as part of a single-event multilevel surgery (SEMLS) and who had undergone preoperative and postoperative three-dimensional (3D) gait analysis between January 1995 and December 2012. Relevant kinematic values, including peak knee flexion, knee range of motion, and timing of peak knee flexion in the swing phase and gait deviation index (GDI) score, were the outcome measures. Improvements in rate of angle and GDI score were adjusted by multiple factors such as sex, Gross Motor Function Classification System (GMFCS) level, anatomic type of CP, and concomitant surgeries as the fixed effects, and follow-up duration, laterality, and each subject as the random effects, all of which was performed using a linear mixed model. A total of 290 patients (487 limbs) and 612 3D gait analysis (2-4 per patient) results were finally included in this study. At 2 years after RFT, estimated mean peak knee flexion (1.2°, p=0.005), estimated mean knee range of motion (10.7°, p<0.001), and estimated mean GDI score (7.3, p<0.001) increased significantly. Peak knee flexion in the swing phase occurred 5.4% earlier after surgery compared with that at baseline (p<0.001). In serial postoperative gait analyses, peak knee flexion in the swing phase occurred 0.8% earlier per year in patients with GMFCS level I or II (p=0.021). RFT as part of a SEMLS was effective in treating stiff knee gait. In serial postoperative gait analyses, patients with GMFCS level I or II showed better prognosis than those with level III with regard to timing of peak knee flexion in the swing phase. Prognostic level IV.

Lee SY ，Kwon SS ，Chung CY ，Lee KM ，Choi Y ，Kim TG ，Shin WC ，Choi IH ，Cho TJ ，Yoo WJ ，Park MS ... -  《-》

Ankle and knee coupling in patients with spastic diplegia: effects of gastrocnemius-soleus lengthening.

Baddar A ，Granata K ，Damiano DL ，Carmines DV ，Blanco JS ，Abel MF ... -  《JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME》