Knee Recurvatum in Children With Spastic Diplegic Cerebral Palsy.

BACKGROUND: The purpose of this study is to determine which factors drive patients with diplegic cerebral palsy to walk without knee recurvatum despite hyperextension of the knee on physical examination. METHODS: A retrospective review was conducted of all data collected in the Gait Analysis Laboratory between 1999 and 2014. Patients with spastic diplegic cerebral palsy and at least 5 degrees of knee extension on clinical examination were identified for the study. After IRB approval, a total of 60 children ranging in age from 4 to 17 were included in the study. There were 27 female patients. Gross Motor Function Classification System level was distributed in the population as follows: 34 patients at Gross Motor Function Classification System level I, 18 at level II, and 8 at level III. Patients were excluded from this study if they had extrapyramidal involvement, history of selective dorsal rhizotomy or lower extremity surgery. Patient who received botulinum toxin A injections within 1 year of the study were excluded as well. Patients were divided into 2 groups: children that walked with knee hyperextension (KH) and children that walked without knee hyperextension (KF, "knee flexion"). There were 15 subjects in the KH group and 45 subjects in the KF group. Motion Laboratory evaluation included a comprehensive examination, kinematics, and kinetic analysis with a VICOM system. All data were analyzed with unpaired t test to detect differences between the 2 groups. All statistical analysis was done only for the right legs (unless the right leg did not meet the exclusion then the left leg was analyzed) to meet the statistical requirement for independence. The Pearson correlation was applied to correlate the maximum knee extension in stance with maximum ankle dorsiflexion in stance. RESULTS: The static measurement of dorsiflexion with knee flexed showed statistically significant difference (P=0.004) with KH group having 2.3±11.6 degrees and KF group having 13.1±12.2 degrees. There was also a statistically significant difference in the static measurement of dorsiflexion with knee extended (P=0.0014) with KH group having -3.3±9.0 degrees and KF group having 5.8±9.1 degrees. Maximum dorsiflexion in stance phase also showed significant difference (P=0.0022) with the KH group having 0.1±14.0 degrees and KF group having 11.5±11.2 degrees. Maximum dorsiflexion in stance phase also showed significant difference (P<0.001) with the DH group having 0.1 (SD) 14.0 degrees and KF group having 11.5 (SD) 11.2 degrees. There were no significant differences in popliteal angle measurements or any strength measurement. CONCLUSIONS: Our study shows that the plantar flexion knee extension couple is the major contributing factor to cause patients with passive knee hyperextension to walk in a recurvatum pattern. This would have implications of further treatment of the knee hyperextension in stance. LEVEL OF EVIDENCE: Level III-case-control study.

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.

Coronal plane knee moments improve after correcting external tibial torsion in patients with cerebral palsy.

BACKGROUND: External tibial torsion causes an abnormal axis of joint motion relative to the line of progression with resultant abnormal coronal plane knee moments and affects lever arm function of the foot in power generation at the ankle. However, it is unclear whether surgical correction of the tibial torsion corrects the moments and power. QUESTIONS/PURPOSES: We evaluated whether surgical correction of external tibial torsion in patients with cerebral palsy would correct the abnormal coronal plane knee moments and improve ankle power generation. METHODS: We studied 22 patients (26 limbs) with cerebral palsy (Gross Motor Function Classification System Level I or II) who underwent distal internal rotation osteotomies for correction of external tibial torsion as part of a multilevel surgical intervention. There were 10 males and 12 females with a mean age at surgery of 14 years (range, 6.8-20.9 years). All patients had pre- and postoperative standardized clinical evaluation and computerized three-dimensional gait analysis. Minimum followup was 9 months (average, 13 months; range, 9-19 months). RESULTS: On physical examination, the mean (± SD) transmalleolar axis improved from 43° ± 10° preoperatively to 20° ± 7° postoperatively. Mean knee rotation improved kinematically from 40° ± 9° preoperatively to 21° ± 9° postoperatively. Twenty-two of 26 limbs (88%) improved in one or both peaks of the abnormal coronal plane knee moments. Ankle power generation did not change from preoperative (1.6 ± 0.7 W/kg) to postoperative (1.6 W/kg). CONCLUSIONS: Correction of external tibial torsion in ambulatory patients with cerebral palsy improves the kinematic and kinetic deviations identified by gait analysis. LEVELS OF EVIDENCE: Level IV, therapeutic series. See Guidelines for Authors for a complete description of levels of evidence.

Iliopsoas tenotomy at the lesser trochanter versus at the pelvic brim in ambulatory children with cerebral palsy.

BACKGROUND: Progressive hip flexion deformity is a common problem in ambulatory children with spastic cerebral palsy, causing static and dynamic deformity. The iliopsoas muscle is recognized as a major deforming force in the development of this problem. Many clinicians address this problem by lengthening the iliopsoas, either in an intramuscular location at the pelvic brim or by complete tenotomy at the lesser trochanter. The goal of this study was to compare the outcomes of patients with ambulatory cerebral palsy who had intramuscular lengthening at the pelvic brim to those who underwent complete release of the iliopsoas tendon at the level of the lesser trochanter. METHODS: Twenty patients were included in the study, 11 of whom had iliopsoas release at the lesser trochanter (group 1) and 9 of whom had intramuscular lengthening at the pelvic brim (group 2). All patients had physical examinations, plus kinematic and kinetic analyses in our gait laboratory before and 1 year after surgery. RESULTS: Hip flexion contracture was decreased significantly only in group 1, although there was a trend of decrease in group 2. There was a significant increase in maximum hip extension in terminal stance and a reciprocal decrease in maximum swing phase hip flexion in group 1, with a similar trend that did not reach significance in group 2. Stride length increased significantly in both groups. There was no significant change in power generation of hip flexion during the swing phase in either group. CONCLUSIONS: We found improved static and dynamic parameters of hip extension after iliopsoas lengthening and did not detect any adverse kinematic or kinetic change in hip function after surgery. The improvement was more robust in the group who underwent release at the lesser trochanter. Because there are no adverse effects of iliopsoas release from the lesser trochanter and the improvement in hip extension is greater, this approach should be considered in ambulatory patients with spastic diplegia when a hip flexor weakening procedure is considered. LEVEL OF EVIDENCE: Comparative cohort study, level III, case-control study.

Does tendon lengthening surgery affect muscle tone in children with cerebral palsy?

The objective of this study was to determine if surgical lengthening of the hamstrings and gastrocnemius/Achilles complex affects muscle tone in patients with cerebral palsy. The question was if the dynamic component of muscle length changes after orthopedic surgery. A retrospective study was performed on ambulatory children with cerebral palsy who underwent either hamstring lengthening or gastrocnemius/Achilles tendon lengthening. A total of 135 consecutive patients with an average age of 13 years were included in the study. A single random side was selected for children with bilateral surgery and the affected limb was analyzed for those undergoing unilateral surgery. The popliteal angle measurement was performed with a quick and slow stretch, as well as the ankle dorsiflexion, and measurements were made using a goniometer. The difference (delta ml) between initial grab with fast stretch and end of range (EOR) with slow stretch was used as a measure of spasticity. The Bohannon modification of the Ashworth score was also assessed. Postoperatively, 18 degrees popliteal angle improvement in end-of-range and 32 degrees improvement in quick stretch in the hamstrings group were noted, with change in slow stretch, quick stretch and delta ml (comparison between quick and slow stretch) being significant at p < .0001. In the triceps surae group, 14 degrees ankle dorsiflexion improvement in end-of-range, and 18 degrees improvement in quick stretch were noted postoperatively, with change in slow stretch, quick stretch and delta ml at p < .0001, p < .0001, and p < .0180 respectively. Ashworth scale was reduced by at least one grade in 89% of subjects in the hamstring group and 78% of subjects in the triceps surae group of the children with preoperative Ashworth 3 and above.

Length and force of the gastrocnemius and soleus during gait following tendo Achilles lengthenings in children with equinus.

Nine subjects (12 sides) with cerebral palsy who walked in equnius were evaluated prior to and 1 year after surgical tendo Achilles lengthening. Gastrocnemius and soleus length [Gait Posture, 6 (1997) 9] and plantarflexor force [Gait Posture, 6 (1997) 9; J Biomech, 23 (1990) 495] were calculated. The length of the gastrocnemius and soleus increased significantly (P<0.01) following the intervention. Force output of the triceps surae during push-off increased significantly (13.95 N/kg body weight (BW) preop to 30.31 N/kg BW postop; P<0.01). Assessment of the force-length capacity of the triceps surae in candidates for tendo Achilles lengthenings may identify individuals at risk of residual weakness and iatrogenic crouch.

Motion of the center of mass in children with spastic hemiplegia: balance, energy transfer, and work performed by the affected leg vs. the unaffected leg.

Asymmetry between limbs in people with spastic hemiplegic cerebral palsy (HEMI) adversely affects limb coordination and energy generation and consumption. This study compared how the affected leg and the unaffected leg of children with HEMI would differ based on which leg trails. Full-body gait analysis data and force-plate data were analyzed for 31 children (11.9 ± 3.8 years) with HEMI and 23 children (11.1 ± 3.1 years) with typical development (TD). Results showed that peak posterior center of mass-center of pressure (COM-COP) inclination angles of HEMI were smaller than TD when the affected leg trailed but not when the unaffected leg trailed. HEMI showed greater peak medial COM-COP inclination angles and wider step width than TD, no matter which leg trailed. More importantly, when the affected leg of HEMI trailed, it did not perform enough positive work during double support to propel COM motion. Consequently, the unaffected leg had to perform additional positive work during the early portion of single support, which costs more energy. When the unaffected leg trailed, the affected leg performed more negative work during double support; therefore, more positive work was still needed during early single support, but energy efficiency was closer to that of TD. Energy recovery factor was lower when the affected leg trailed than when the unaffected leg trailed; both were lower than TD. These findings suggest that the trailing leg plays a significant role in propelling COM motion during double support, and the 'unaffected' side of HEMI may not be completely unaffected. It is important to strengthen both legs.

Comparison of hamstring transfer with hamstring lengthening in ambulatory children with cerebral palsy: further follow-up.

BACKGROUND: Overactivity or contractures of the hamstring muscles in ambulatory children with cerebral palsy (CP) can lead to either a jump gait (knee flexion associated with ankle plantar flexion) or a crouch gait (knee flexion associated with ankle dorsiflexion). Hamstring lengthening is performed to decrease stance knee flexion. However, this procedure carries the potential risk of weakening hip extension power as well as recurrence over time; therefore, surgeons have adopted a modified procedure wherein the semitendinosus and gracilis are transferred above the knee joint, along with lengthening of the semimembranosus and biceps femoris. PURPOSE: The purpose of our study is to evaluate the differences between hamstring lengthening alone (HSL group) and hamstring lengthening plus transfer (HST group) in the treatment of flexed knee gait in ambulatory children with CP. We hypothesized that recurrence of increased knee flexion in the stance phase will be less in the HST group at long-term follow-up, and hip extensor power will be better preserved. METHODS: Fifty children with CP who underwent hamstring surgery for flexed knee gait were retrospectively reviewed. All subjects underwent a pre-operative gait study, a follow-up post-operative gait study, and a long-term gait study. The subjects were divided into two groups; HSL group (18 subjects) or HST group (32 subjects). The mean age at surgery was 9.9 ± 3.3 years. The mean follow-up time was 4.4 ± 0.9 (2.7-6.3) years. RESULTS: On physical examination, both groups showed improvement in straight leg raise, knee extension, popliteal angle, and maximum knee extension in stance at the first post-op study, and maintained this improvement at the long-term follow-up, with the exception of straight leg raise, which slightly worsened in both groups at the final follow-up. Both groups improved maximum knee extension in stance at the initial follow-up, and maintained this at the long-term follow-up. Only the HST group showed significant (p < 0.05) improvement in the peak hip extension power in stance at the first post-op study, and this increased further at the final follow-up. In the HSL group, there was an initial slight decrease in the hip extension power, which subsequently increased to pre-operative values at the long-term study. Only the HST group showed increase of the average anterior pelvic tilt at the long-term follow-up study, although this was small in magnitude. There were two subjects who developed knee recurvatum at the post-op study, and both were in the HST group. CONCLUSIONS: There is no clear benefit in regards to recurrence when comparing HST to HSL in the long term. In both HSL and HST, there was reduction of stance phase knee flexion in the long term, with no clear advantage in either group. Longer follow-up is needed for additional recurrence information. There was greater improvement of hip extension power in the HST group, which may justify the additional operative time of the transfer. SIGNIFICANCE: This study helps pediatric orthopedic surgeons choose between two different techniques to treat flexed knee gait in patients with CP by showing the long-term outcome of both procedures.

Comparison of hamstring lengthening with hamstring lengthening plus transfer for the treatment of flexed knee gait in ambulatory patients with cerebral palsy.

PURPOSE: Children with spastic diplegic and hemiplegic cerebral palsy frequently ambulate with flexed knee gait. There has been concern that hamstring lengthening used to treat this problem may weaken hip extension. This study evaluates the primary outcome of hamstring transfer plus lengthening in comparison with traditional hamstring lengthening in treating flexed knee gait in ambulatory patients with cerebral palsy. METHODS: A total of 47 children (67 lower limbs) ranging in age from 5 to 17 years old were included in this study. All subjects underwent a variety of additional surgeries at the time of the hamstring surgery as part of a multilevel treatment plan. All patients who met the inclusion criteria were divided into two groups, the hamstring lengthening alone group (HSL) and the hamstring transfer plus lengthening group (HST). Full gait analysis studies were done for all subjects pre-operatively and 1 year post-operatively. RESULTS: There were 25 patients (35 limbs) in the HSL group and 22 patients (32 limbs) in the HST group. There was no significant difference in age, gender, or the time from surgery to post-operative gait analysis between groups. On physical examination, both HSL and HST groups showed improvement in passive knee extension, popliteal angle, and straight leg raise. Maximum knee extension in stance phase was improved in both groups. The maximum hip extension in late stance phase was significantly improved only in the HST group. The peak hip extension power in stance phase showed significant improvement only in the HST group and a significant decrease for the HSL group. CONCLUSIONS: The findings of this study demonstrated that both the HSL and HST procedures resulted in similar amounts of improvement in passive range of motion of the knee, as well in knee extension in stance during gait at 1 year post-operatively. However, with the HST procedure, there was better preservation of hip extension power and improved hip extension in stance. The HST procedure should be considered when hamstring surgery is performed.

Comparison of rectus femoris transposition with traditional transfer for treatment of stiff knee gait in patients with cerebral palsy.

PURPOSE: To assess the outcome of children with cerebral palsy following reposition of the distal rectus femoris tendon for treatment of stiff knee gait. METHODS: Children with cerebral palsy with stiff knee gait who underwent rectus femoris transfer were studied retrospectively. Inclusion criteria were cerebral palsy of diplegic or quadriplegic type, preoperative and 1 year postoperative three-dimensional motion analysis, and no other surgery except rectus femoris transfer at the time of study. The patients were separated into two groups: in group I, the rectus femoris was transferred to the distal medial hamstring tendons, either the gracilis or the semitendinosus; in group II, the distal tendon of the rectus femoris was transposed laterally and attached to the iliotibial band/intermuscular septum. RESULTS: Peak knee flexion during swing phase, total dynamic knee range of motion, knee range of motion during swing phase, and time to peak knee flexion during swing phase were all improved in both groups. Hip and pelvic kinematics were not influenced by the surgery. Velocity, stride length, and cadence were all improved following the surgery. There was no difference between the transfer group and the transposition group. CONCLUSION: These findings suggest that distal transfer of the rectus femoris is effective in improving swing phase knee function by diminishing the mechanical effect of the dysphasic swing phase activity of the rectus femoris, not by converting the rectus femoris to an active knee flexor.

Outcome of patients after Achilles tendon lengthening for treatment of idiopathic toe walking.

Fifteen children who were diagnosed with idiopathic toe walking that cannot be corrected by nonoperative treatment were assessed by clinical examination and computer-based gait analysis preoperatively and approximately 1 year after Achilles tendon lengthening. Passive dorsiflexion improved from a mean plantarflexion contracture of 8 degrees to dorsiflexion of 12 degrees after surgery. Ankle kinematics normalized, with mean ankle dorsiflexion in stance improving from -8 to 12 degrees and maximum swing phase dorsiflexion improving from -20 to 2 degrees. Peak ankle power generation increased from 2.05 to 2.37 W/kg but did not reach values of population norms. No patient demonstrated clinically relevant triceps surae weakness or a calcaneal gait pattern. Seven patients had a stance phase knee hyperextension preoperatively, and 6 of these corrected after surgery. Achilles tendon lengthening improves ankle kinematics without compromising triceps surae strength; however, plantarflexion power does not reach normal levels at 1 year after surgery.