K. Patrick Do

Changes in pelvic rotation after soft tissue and bony surgery in ambulatory children with cerebral palsy.

The authors performed a retrospective review of pelvic rotation in 59 children with cerebral palsy who underwent lower extremity surgery and pre- and postoperative gait analysis. Two groups were studied: a femoral derotation osteotomy (FDRO) group and a soft tissue surgery only (no FDRO) group. Both groups exhibited abnormal pelvic rotation preoperatively and normalization of this abnormal pelvic rotation postoperatively. Though the mean change in pelvic rotation was small (3.3° ± 6.0°), some patients demonstrated postoperative changes as large as 21°. Variability in pelvic rotation was greater in the no FDRO group than in the FDRO group. Improvement in pelvic rotation occurred both in children with unilateral (hemiplegic) involvement and in those with bilateral (diplegic or quadriplegic) involvement. Surgeons planning lower extremity surgery in children with cerebral palsy should expect improvement in abnormal pelvic rotation in both hemiplegic and diplegic patients, whether or not bony surgery is planned in addition to soft tissue surgery.

Gait patterns in children with limb length discrepancy

Background: Very few articles describe the compensations in gait caused by limb-length discrepancy (LLD). Song and colleagues explored kinematic and kinetic variables utilizing work equalization as a marker of successful compensation for LLD. They found no difference in strategies based on the location of pathology. The purpose of this study was to define the various gait patterns in patients with LLD and the impact of these compensations on gait kinetics. Methods: Forty-three children (mean age 12.9±3.7 y) with LLD >2 cm were evaluated in the motion lab using a VICON motion system with 2 AMTI force plates. Etiologies included Legg-Calve-Perthes, developmental hip dysplasia, growth plate damage due to infection or trauma, congenital shortening of the femur or tibia, and syndromes creating shortening of the limb. Evaluation included physical examination and 3-dimensional motion data generated using the model described by Vicon Clinical Manager (VCM). For data analysis, 3 representative trials were processed with the Plug-in Gait lower-body model using the “VCM spline” filter. Walking strategies were identified by visual review. A kinematic threshold of 2 SD away from normal values was used for inclusion in each group. Strategies included: (1) pelvic obliquity with the short side lower (<−1.5 degrees); (2) flexion of the knee of the longer leg in stance (>5.2 degrees); (3) plantar flexion of the ankle on the shorter leg through the gait cycle (<0 degrees); and (4) early plantarflexion crossover of the shorter limb (plantarflexion crossover occurred before 35% of the gait cycle). Variables were extracted into Excel using PECS (Vicon Motion Systems). The mean of the 3 trials was used for analysis. Scanograms were used to establish lengths of the femur and the lower leg including the foot. The percentage difference for the subject (%LLD) was calculated as the leg length between the 2 sides divided by the length of the long side. The total mechanical work over the stride was the sum of the positive work and the absolute value of the negative work in all planes. Paired t tests were used to analyze the work differences between the short limb versus the long limb. Unpaired t tests were used to compare between the different groups (short tibias, short femurs, and controls). Results: Distribution of single strategies for the group included: pelvis (11), equinis (5), vaulting (7), knee flexion (3); 17 subjects used multiple strategies. If the discrepancy was in the femur, patients chose a more distal compensation strategy, utilizing ankle movements, which resulted in more work at the ankle joint on the short limb compared with normal (P<0.0001). All subjects with tibia shortening showed pelvic obliquity (3 combined with knee flexion), which caused more work at the hip joint on the short limb compared with normal (P<0.01). Total mechanical work on the uninvolved limb was above normal for all groups (P<0.0001). Conclusions: Our study contradicts previous literature that found no difference in strategy on the basis of location of the shortening and also a higher number of children with pelvic obliquity than previously described. It appears that different compensation schemes are used by patients with LLD. The increase in work may have long-term implications for management. Future studies will include changes in kinematics and work, after intervention. Better understanding of postoperative changes from different surgical methods may provide more insight for preoperative planning and may lead to a more satisfactory outcome for specific patients. Level of Evidence: Level II.

Comparison of Rectus Femoris Transfer Surgery Done Concomitant With Hamstring Lengthening or Delayed in Patients With Cerebral Palsy.

Background: Children with spastic cerebral palsy frequently develop stiff knee gait. A common treatment of flexed knee gait is lengthening of the hamstring tendons. It has been shown that minimum knee extension improves after hamstring surgeries. However, it has been observed that a decreased peak knee flexion in swing may be a complication of hamstring lengthening (HSL). This has been noted to occur because of an overactive rectus femoris during the swing phase of gait. A common treatment of decreased knee flexion in swing is distal rectus femoris transfer (DRFT). The purpose of this study is to compare the differences between doing DRFT concomitantly with HSL and doing delayed DRFT after HSL. Methods: A total of 111 children with cerebral palsy (74 males and 37 females) who underwent HSL were reviewed retrospectively. All patients who met the inclusion criteria were divided into 3 groups, 28 subjects in the HSL alone group (H), 57 subjects in the HSL with concomitant rectus femoris transfer group (C), and 26 subjects in the HSL with delayed rectus femoris transfer group (D). Results: The groups had similar minimum knee flexion in stance preoperatively and postoperatively. Group D’s minimum knee flexion in stance improved to 5.5±12.7 degrees after HSL, but increased to 8.8±11.6 degrees after DRFT. Groups D and H had statistically significant reduction in maximum knee flexion in swing after HSL (P<0.05). Maximum knee flexion in swing was statistically significantly reduced in the D group after DRFT (P<0.05), but the C group was not statistically different from preoperative after DRFT (P>0.05). The C and D groups had similar total knee excursion postoperatively. The H group had less knee excursion than the other 2 groups, but it was not significant. Conclusions: The group that had DRFT concomitantly with HSL maintained maximum knee flexion in swing phase postoperatively. Although the group that had delayed DRFT had a reduction in maximum knee flexion after isolated HSL, gains in swing phase motion were achieved after delayed DRFT (comparable to that of the simultaneous group). Level of Evidence: Level II.