Mid-term development of hamstring tendon length and velocity after distal femoral extension osteotomy in children with bilateral cerebral palsy: a retrospective cohort study.

Flexed knee gait can be treated with distal femoral extension osteotomy (DFEO) and additional patellar tendon advancement (PTA) in children with cerebral palsy (CP). This study assesses changes in hamstring muscle tendon length (MTL) and velocity after DFEO (+PTA). Nineteen children (mean age 13y [standard deviation 3y] at surgery) with CP and flexed knee gait who were treated with DFEO (15 limbs) or DFEO+PTA (10 limbs) were retrospectively included in this study. Gait analyses were performed preoperatively (E0), 1 year postoperatively (E1), and for 10 limbs additionally 2 to 5 years postoperatively (E2). Hamstring MTL and velocities were assessed at all examination dates using OpenSim. Hamstring MTL and velocity did not change significantly over time. From E0 to E1, knee flexion in stance improved for both DFEO and DFEO+PTA (p<0.05), knee flexion in swing only improved after DFEO+PTA (p<0.05). The improved knee flexion in stance and swing was maintained at E2. DFEO led to a significant improvement in knee kinematics at E1 which was maintained at E2. DFEO seems to prevent recurrent hamstring tightness but does not lead to lengthened or fastened hamstrings. Distal femoral extension osteotomy (DFEO) does not change hamstring muscle tendon length. DFEO does not change hamstring lengthening velocity. DFEO leads to a significant improvement in knee kinematics. Changes in knee kinematics after DFEO can be maintained at mid-term. DFEO seems to prevent recurrent hamstring tightness.

Salami F ，Wagner J ，van Drongelen S ，Klotz MCM ，Dreher T ，Wolf SI ，Niklasch M ... -  《-》

Is simultaneous hamstring lengthening necessary when performing distal femoral extension osteotomy and patellar tendon advancement?

Crouch gait is common in individuals with cerebral palsy. Recently published data has shown that distal femoral extension osteotomy with patellar tendon advancement (DFEO/PTA) is an effective procedure to correct crouch gait in the presence of a knee flexion contracture and quadriceps insufficiency. Short length and slow lengthening rate (velocity) of the hamstrings are indications for hamstrings surgery. We empirically believed that hamstrings surgery would not be necessary to improve hamstring function when DFEO/PTA are performed. This hypothesis was examined in a retrospective review of hamstrings length and velocity before and after DFEO/PTA. 51 limbs in 32 individuals with a diagnosis of CP who underwent DFEO/PTA without concomitant hamstring surgery were included in the study. Pre and post-operative peak medial hamstring length and velocity z-scores were calculated using a musculoskeletal model. A subset of limbs with pre-operative values above or below two SD from the control mean emerged and were called long or short respectively. Members of this subset would often be considered candidates for hamstrings surgery. Categorical length outcomes were derived, with analogous categories for velocity. The mean peak hamstring length z-score improved pre- to post-operatively from -2.2 to -0.76 (p<0.001). The mean peak velocity z-score improved from -3.1 to -1.5 (p<0.001) [Figure 1]. DFEO/PTA surgery without concomitant hamstrings surgery led to significantly longer or faster hamstrings. Specifically, we saw 94% good or neutral results for length correction and 80% good or neutral results for velocity correction. Because crouch improved without posterior pelvic tilting, and because both hamstring length and velocity increased substantially, we conclude that concomitant hamstring surgery is rarely needed when performing DFEO/PTA.

Healy MT ，Schwartz MH ，Stout JL ，Gage JR ，Novacheck TF ... -  《-》

Distal femoral osteotomy and patellar tendon advancement for the treatment of crouch gait in patients with bilateral spastic cerebral palsy.

Crouch gait, or flexed knee gait, represents a common gait pattern in patients with spastic bilateral cerebral palsy (CP). Distal femoral extension and/or shortening osteotomy (DFEO/DFSO) and patellar tendon advancement (PTA) can be considered as viable options when knee flexion contractures are involved. Better outcomes have been reported after a combination of both, independently of the presence of knee extensor lag. In this study, we evaluated the clinical and kinematic outcomes of these procedures. We reviewed a cohort of 52 limbs (28 patients) who were treated for crouch gait by DFEO/DFSO alone (group 1, n = 15) or DFEO/DFSO + PTA (group 2, n = 37) as a part of single event multilevel surgery (SEMLS). The mean age at surgery was 14 years, and the mean follow-up time was 18 months. The physical examination data and three-dimensional standardized gait analysis were collected and analyzed before the surgery and postoperatively. Overall knee range of motion improved in all limbs. The knee flexion decreased significantly in both groups at initial, mid, and terminal stance. Hip flexion significantly decreased in mid-stance for limbs in group 2. Both clinical and gait parameters were most improved in limbs who underwent DFEO/DFSO + PTA. Increased pelvic tilt was observed in both groups after surgery. Although DFEO/DFSO alone was successful in correcting knee flexion contractures, PTA has helped to improve knee extensor lag and knee extension during gait. Therapeutic level IV.

Nabian MH ，Zadegan SA ，Mallet C ，Neder Y ，Ilharreborde B ，Simon AL ，Presedo A ... -  《-》

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.

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.

Boyer ER ，Stout JL ，Laine JC ，Gutknecht SM ，Oliveira LH ，Munger ME ，Schwartz MH ，Novacheck TF ... -  《-》

Long-term muscle changes after hamstring lengthening in children with bilateral cerebral palsy.

To evaluate short-term (1y postoperatively; E1) and long-term (at least 4y postoperatively; E2) changes in hamstring muscle-tendon length (MTL) and lengthening velocity after hamstring lengthening in children with bilateral cerebral palsy (CP). Three-dimensional gait analysis was performed in 19 children (16 males, 3 females; 36 limbs; mean age at surgery 9y [SD 3y]; range 6-10y) with flexed knee gait, preoperative ankle dorsiflexion lower than 20 degrees, and CP before bilateral hamstring lengthening (E0), at E1 and E2. Hamstring MTL (normalized by leg length) and velocity were assessed via OpenSim software. MTL increased from E0 to E1 (p=0.004) and decreased from E1 to E2 (p<0.020). Hamstring lengthening velocity did not change. In the subgroup with short, not slow hamstrings, the increase in MTL was maintained at E2. Hamstring lengthening is an efficient procedure to lengthen short and/or slow hamstrings short-term. The desired outcome with maintenance of the postoperative changes in hamstring MTL is only achieved for preoperatively short, not slow hamstrings. Surgical hamstring lengthening can be confirmed via musculoskeletal modelling in OpenSim software. Surgical hamstring lengthening in cerebral palsy does not change hamstring lengthening velocity. Short, not slow hamstrings present a long-lasting muscle-tendon length (MTL) increase after hamstring lengthening. Changes in MTL after hamstring lengthening cannot be maintained for slow hamstrings. MTL does not change after hamstring lengthening for neither short nor slow hamstrings.

Salami F ，Brosa J ，Van Drongelen S ，Klotz MCM ，Dreher T ，Wolf SI ，Thielen M ... -  《-》