Sagittal knee kinematics following combined hamstring lengthening and rectus femoris transfer

The purpose of this study was to review knee kinematics following combined hamstring lengthening and rectus femoris transfer. Previous findings reported in the literature include kinematic changes in the magnitude of stance-phase maximum knee flexion, stance-phase minimum knee flexion (extension), and swing-phase maximum knee flexion; the timing of swing-phase maximum knee flexion and swing-phase minimum knee flexion (extension); and total knee excursion. Twenty-three children underwent bilateral (22) or unilateral (1) hamstring lengthening and rectus femoris transfer (45 knees) at the Shriners Hospitals for Children in Lexington, KY between January 1996 and December 2001. Sagittal knee kinematic data were obtained as part of a complete gait study accomplished before surgery and at 1 year after surgery. Values were compared using a paired t test method set at a p < .05 level to determine statistical significance. Changes were seen in the magnitude of stance-phase maximum knee flexion, stance-phase minimum knee flexion (extension), swing-phase maximum knee flexion, and swing-phase minimum knee flexion (extension); in the timing of swing-phase maximum knee flexion; and in total knee excursion.     

Treatment of stiff-knee gait in cerebral palsy: a comparison by gait analysis of distal rectus femoris transfer versus proximal rectus release

Two groups of patients with cerebral palsy (CP) were studied pre- and postoperatively by gait analysis after proximal release or distal transfer of the rectus femoris for treatment of knee stiffness in swing phase. In the first group studied, 12 patients underwent proximal rectus femoris muscle release. In the second group, 10 patients underwent distal rectus femoris transfer. After surgery, peak knee flexion was increased 9.1 degrees in swing phase by proximal rectus release and 16.2 degrees by distal rectus transfer. Hip motion throughout the gait cycle was not significantly affected by either operation, and no tendency for a crouch gait was observed after either procedure.     

Outcome of hamstring lengthening and distal rectus femoris transfer surgery

To evaluate the outcome of hamstring lengthening and distal rectus femoris transfer, a retrospective study was performed comparing preoperative and postoperative gait analysis data from 16 children with neurologic involvement. Postoperatively, the timing of peak knee flexion during swing and the total arc of knee motion significantly improved. Hamstring range of motion and knee extension at terminal swing significantly improved, but stride length and gait velocity did not for the overall population. Patients who used braces postoperatively showed an improvement in stride length and velocity when wearing orthoses. This suggests that postoperative bracing may be needed in some patients to maximize the surgical outcome.     

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. No financial support was received for this study.     

Conversion of biarticular to monoarticular muscles as a component of multilevel surgery in spastic diplegia

We treated 20 children (40 limbs) with diplegic cerebral palsy who could walk by multilevel soft tissue operative procedures including conversion of the biarticular semitendinosus and gastrocnemius to monoarticular muscles. The mean age at surgery was 11.5 years (5.6 to 17.0). All patients underwent clinical and radiological examination and three-dimensional instrumented gait analysis before and at a mean of 3.1 years (2.0 to 4.5) after surgery. The passive range of movement at the ankle, knee and hip showed improvement at follow-up. Kinematic parameters indicated a reduced pelvic range of movement and improvement of extension of the knee in single stance after operation (p < 0.0001). However, post-operative back-kneeing was detected in five of the 40 limbs. The kinetic studies showed that the power of the hamstrings and plantar flexors of the ankle was maintained while the maximum knee extensor moment during stance was reduced. The elimination of knee flexor activity of semitendinosus and gastrocnemius combined with transfer of distal rectus femoris led to an improvement in gait as confirmed by gait analysis.     

Rectus Femoris Distal Tendon Resection Improves Knee Motion in Patients With Spastic Diplegia

Background  

Children with spastic diplegia frequently show excessive knee extension (stiff-knee gait) throughout swing phase, which may interfere with foot clearance. Abnormal rectus femoris activity is commonly associated with a stiff-knee gait. Rectus femoris transfer has been recommended to enhance knee flexion during swing. However, recent studies suggest the transfer does not generate a knee flexor moment but diminishes knee extension moment in swing and MRI studies show the transferred tendons can be constrained by scarring to underlying muscles. Thus, it is possible knee flexion would be improved by distal rectus release rather than transfer since it would not be adherent to the underlying muscles.     

Rectus Femoris Transfer Improves Stiff Knee Gait in Children With Spastic Cerebral Palsy

Background  

Stiff knee gait is common among children with ambulatory cerebral palsy (CP). When surgery is indicated, rectus femoris transfer as a primary treatment enhances knee range of motion, reduces time to peak knee flexion, increases peak knee flexion, and reduces toe drag.     

Kinematic and kinetic outcomes after identical multilevel soft tissue surgery in children with cerebral palsy

This study evaluates the outcomes of multilevel soft tissue surgery in 31 ambulatory children (n = 39 sides) with cerebral palsy. All children had undergone rectus femoris transfer, hamstring lengthening, and gastrosoleus lengthening for the purpose of correcting sagittal plane abnormalities. There were no simultaneous bony surgeries. Preoperative and postoperative evaluation consisted of clinical assessment and gait analysis, including 3-dimensional kinematics and kinetics. Results demonstrated improvements in knee and ankle function. At the knee, there was a decrease in mean flexion at initial contact (from 31 degrees [SD, +/-8 degrees] to 21 degrees [SD, +/-10 degrees]) and in stance (mean stance, 22 degrees [SD, +/-12 degrees] to 16 degrees [SD, +/-11 degrees]) associated with a decreased mean internal extensor moment in stance (from 0.09 Nm/kg [SD, +/-0.24 Nm/kg] to -0.03 [SD, +/-0.22 Nm/kg]). At the same time, knee flexion was preserved in swing and occurred earlier. At the ankle, mean dorsiflexion improved at the time of examination (from 8 degrees [SD, +/-9 degrees] to 14 degrees [SD, +/-11 degrees] with the knee in extension), in terminal stance (peak from 7 degrees [SD, +/-9 degrees] to 12 degrees [SD, +/-8 degrees]), and in swing. Peak ankle power generation in stance was preserved and shifted later in stance toward push-off, with no functional weakening of the ankle plantar flexors. A longer-term assessment of a subset of patients with a second postoperative gait analysis at a mean of 4 years after surgery showed that gains measured at 1 year were maintained during the longer term. A subgroup demonstrating a jump knee gait pattern (as defined by excessive knee flexion at initial contact followed by rapid knee extension to full knee extension in midstance) had a tendency to go into knee hyperextension in stance with resultant net knee flexor moment after surgery. This raises concern about the indications for hamstring lengthening in this patient group.     

Sagittal knee kinematics after rectus femoris transfer without hamstring lengthening

The purpose of this study was to assess the sagittal knee kinematics of rectus femoris transfer without hamstring lengthening. A retrospective review of seventeen children (29 knees) was performed. Gait analysis was performed prior to surgery and repeated at a minimum of one year after surgery. Sagittal knee kinematics were analyzed. Stance minimum knee flexion increased 7 degrees; swing maximum knee flexion increased 5 degrees; and swing minimum knee flexion increased 5 degrees. The present study confirmed previously reported increases in swing maximum knee flexion. Increases in stance minimum knee flexion and swing minimum knee flexion were also found. These findings have not been previously reported.     

Three-dimensional muscle-tendon geometry after rectus femoris tendon transfer

BACKGROUND: Rectus femoris tendon transfer is performed in patients with cerebral palsy to improve knee flexion during walking. This procedure involves detachment of the muscle from its insertion into the quadriceps tendon and reattachment to one of the knee flexor muscles. The purpose of the present study was to evaluate the muscle-tendon geometry and to assess the formation of scar tissue between the rectus femoris and adjacent structures. METHODS: Magnetic resonance images of the lower extremities were acquired from five subjects after bilateral rectus femoris tendon transfer. A three-dimensional computer model of the musculoskeletal geometry of each of the ten limbs was created from these images. RESULTS: The three-dimensional paths of the rectus femoris muscles after transfer demonstrated that the muscle does not follow a straight course from its origin to its new insertion. The typical muscle-tendon path included an angular deviation; this deviation was sharp (>35 degrees ) in seven extremities. In addition, scar tissue between the transferred rectus femoris and the underlying muscles was visible on the magnetic resonance images. CONCLUSIONS: The angular deviations in the rectus femoris muscle-tendon path and the presence of scar tissue between the rectus femoris and the underlying muscles suggest that the beneficial effects of rectus femoris tendon transfer are derived from reducing the effects of the rectus femoris muscle as a knee extensor rather than from converting the muscle to a knee flexor. These findings clarify our understanding of the mechanism by which rectus femoris tendon transfer improves knee flexion.     

Postoperative gait velocity and mean knee flexion in stance of ambulatory children with spastic diplegia four years or more after multilevel surgery

Factors associated with longer-term outcomes of multilevel orthopaedic surgery in ambulatory children with cerebral palsy using a multivariate approach were evaluated using a retrospective pretest-posttest design. The population included 20 ambulatory children with spastic diplegia who had undergone multilevel orthopaedic surgery with a minimum of 4-year interval between a preoperative and a postoperative gait assessment. Multiple regression analysis was used to identify factors associated with postoperative velocity and mean knee flexion in stance. Independent variables included in the regression models were velocity, mean knee flexion in stance, age at preoperative evaluation, Gross Motor Function Classification System level, use of ankle-foot orthoses, leg length, age-adjusted body mass index, number of surgical procedures, and range of motion of hip and knee. Children who demonstrated faster postoperative gait velocity 4 years or more after surgery were younger at the time of initial evaluation, had undergone fewer surgical procedures, had faster preoperative gait velocity, used ankle-foot orthoses postoperatively, and had increased hip extension range of motion postoperatively (R = 0.55). Children who demonstrated greater knee flexion in stance 4 years or more after surgery had undergone more surgical procedures, greater postoperative popliteal angle, and less knee extension range of motion (R = 0.73). This study demonstrates the usefulness of a multivariate approach toward understanding and predicting outcomes. The results of this study will provide clinicians and researchers more information about those factors associated with maintained improvements in the longer term and may be useful for treatment planning.     

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.     

髌骨牵引辅助治疗膝关节僵直

膝关节僵直的主要原因是伸膝装置的粘连与挛缩。作者在股四头肌成形、膝关节松解的基础上，应用髌骨牵引，使挛缩的肌肉在持续张力作用下得以延长。由于股直肌的完整性得以保留，避免了股直肌肌腱延长术可能导致的主动伸膝功能的部分丧失。对于陈旧性股骨干骨折，髌骨牵引不影响内固定的稳定性，使骨折的愈合和膝关节功能康复能同时进行。本组２７例，平均随访１年以上。平均屈膝功能由术前的２８°增至１２１°，平均进步９３°，效果满意。     

Sagittal plane positioning of the femoral component in total knee arthroplasty

The authors evaluated 623 total knee arthroplasties to determine the relationship between sagittal plane position of the femoral component and the final range of motion of the prosthetic knee. Two different prostheses were evaluated (Posterior Cruciate Condylar and A.G.C.) radiographically and functionally. Variation in sagittal plane position ranged from 20 degrees flexion to 20 degrees extension. No correlation between the sagittal plane position of the femoral component in either prosthesis and the final knee range of motion could be found. Sagittal plane femoral component position in the prostheses studied did not affect final range of motion when component position was between 20 degrees flexion and 20 degrees of extension.     

Rectus and hamstring surgery in cerebral palsy: a gait analysis study of results by functional ambulation level

The purpose of this study is to determine if children more severely involved with cerebral palsy respond as well to rectus transfer and hamstring surgery as those with less severe involvement. Ninety-nine children were classified as independent community ambulators, crutch/walker-dependent community ambulators, or household/exercise ambulators. Maximum knee extension in stance and total range of knee motion in gait increased following surgery in all groups. Peak knee flexion in swing was maintained in the independent group only, but timing of knee flexion in swing improved in all groups. All groups showed increases in stride length, and the household/exercise group also showed an increase in walking speed. Four of 39 crutch/walker-dependent community ambulators and 13 of 21 household/exercise ambulators progressed to the next higher functional ambulation group.     

Effects of surgical lengthening of the hamstrings without a concomitant distal rectus femoris transfer in ambulant patients with cerebral palsy

Eighteen ambulant patients (32 legs) who had undergone fractional lengthening of the medial and lateral hamstrings without rectus femoris transfer underwent pre- and postoperative gait analysis. A significant increase in the amount of knee extension and a decrease in the amount of peak knee flexion in swing were observed. This decrease in knee flexion signified a change towards more normal speed-related values. Dorsiflexion at initial contact decreased significantly for patients who did not undergo a gastrocnemius lengthening (n = 24). Absolute cadence was significantly lower after surgery, but the change in dimensionless cadence was not significantly different. This difference in the outcome between dimensionless and absolute stride parameters can be attributed to the increase in body height after surgery. The clinical significance of these findings is that it is important to recognize that postoperative effects of surgery on gait in children may, in part, be explained by changes in height and not surgery alone.     

Surgical treatment of knee dysfunction in cerebral palsy

The prerequisites for normal gait are: (1) stability in the stance phase of gait, (2) clearance of the foot in the swing phase, (3) proper foot preposition in swing, and (4) an adequate step length. In the stance phase, the knee provides shock absorption and energy conservation; in the swing phase, it allows foot clearance. To accomplish these functions, the knee must extend fully in stance and flex approximately 60 degrees in swing. Consequently, balanced muscle action at the hip, knee, and ankle joints, combined with adequate acceleration from the hip flexor and triceps surae muscles, is essential. In the crouch gait of spastic cerebral palsy, hamstring lengthening alone often converts the flexed-knee gait to an extended-knee, stiff-legged gait with inadequate swing-phase knee flexion. This unwanted conversion is due to cospasticity of the quadriceps and hamstring muscles. Restoration of normal knee function in patients with spastic paralysis is more successful when fractional hamstring lengthening is combined with a transfer of the distal rectus femoris tendon to either the iliotibial band or the distal tendon of the semitendinosus.     

Predictive value of the Duncan-Ely test in distal rectus femoris transfer

Fifty-six patients who underwent 94 distal rectus femoris transfers and pre- and postoperative gait analyses were retrospectively reviewed. The patients were divided into three groups based on pre- and postoperative Duncan-Ely tests. Group A (34 limbs) had positive tests both before and after surgery. Group B (46 limbs) had positive tests before surgery and negative tests after surgery. Group C (13 limbs) had negative tests both before and after surgery. One limb had a negative test before surgery and a positive test after surgery and was not included in any group. Knee arc increased significantly in both groups with positive preoperative Duncan-Ely tests (groups A and B), but not in the group with negative preoperative tests (group C). The timing of peak knee flexion in swing improved in all groups, but the change was smaller and not statistically significant in the group with negative preoperative tests (group C). The findings of the current study indicate that the Duncan-Ely test may be a helpful predictor of outcome in children for whom distal rectus femoris transfer is being considered. Caution should be exercised when patients have weak quadriceps and a negative Duncan-Ely test before surgery, particularly when concurrent calf lengthening procedures are planned.     

Case series utilizing drop-out casting for the treatment of knee joint extension motion loss following anterior cruciate ligament reconstruction

STUDY DESIGN: Case series. CASE DESCRIPTION: Four patients who had developed knee extension motion loss following anterior cruciate ligament reconstruction were referred to physical therapy for treatment. They were treated with drop-out casting and completed a Lower Extremity Functional Scale at baseline, at the time of application of the drop-out casting, and at discharge. OUTCOMES: Three males and 1 female with a mean age of 20.5 years (range, 18-22 years) were referred to physical therapy a mean of 31 days (range, 19-49 days) following bone-patella tendon-bone autograft anterior cruciate ligament reconstruction. The mean number of physical therapy sessions attended was 29.5 visits (range, 20-47 visits). The mean improvement in knee extension range of motion (ROM) and knee flexion ROM prior to the application of drop-out casting was 4.3 degrees (range, -1 degree to 10 degrees) and 24.3 degrees (range, 0 degree to 40 degrees), respectively. The mean improvement on the Lower Extremity Functional Scale was 10.3 points prior to drop-out casting. At time of discharge, the total mean improvement in knee extension ROM loss was 11.0 degrees (range, 4 degrees to 15 degrees), knee flexion ROM was 30.8 degrees (range, 22 degrees to 35 degrees), and Lower Extremity Functional Scale was 12 points (range, -5 to 21 points). Two of the patients were able to complete a running program without difficulty, while the other 2 patients had difficulty with higher-level activities. DISCUSSION: Despite the low incidence of knee extension ROM loss following surgery, the inability to achieve full knee extension does occur and can have debilitating consequences. When early emphasis of full passive knee extension has been inadequate, these results suggest that improving knee extension motion without inhibiting knee flexion motion is possible with the use of a drop-out cast. Future research should focus on comparison of drop-out casting to dynamic splinting, as well as the optimal frequency and duration of low-load long-duration stretching using a drop-out cast.