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.     

Sagittal knee kinematics after hamstring lengthening

The purpose of this study was to analyze sagittal knee kinematics after hamstring lengthening. A retrospective analysis was performed of 16 children (32 knees) with cerebral palsy who underwent hamstring lengthening as an isolated surgical procedure. Gait analysis was performed before surgery and at a minimum of 1 year after surgery. Decreased stance maximum knee flexion, stance minimum knee flexion, swing maximum knee flexion, and swing minimum knee flexion were noted. Total knee excursion increased. The present study confirmed the previously reported increased total knee excursion with decreased stance minimum and swing maximum knee flexion.     

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.     

Proximal rectus femoris lengthening

There are two main problems with muscle tendon lengthening: thinness created by the technical procedure weakens the tendon, and in short tendons, lengthening may not provide enough length for the amount of joint motion required. In proximal rectus femoris lengthening, the distal ends of the reflected and straight heads are sutured together. Using this technique, the tendon will not be thinned, and a later second lengthening is possible.     

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.     

Long-term outcome of hamstring lengthening versus transfer and the role of biceps femoris lengthening in patients with spastic diplegia and dynamic knee flexion in gait

Background:Orthopedic treatment of flexed-knee gait consists of hamstring lengthening along with surgery at other levels. Transfer of the semitendinosus (hamstring transfer) was introduced to avoid increase of anterior pelvic tilt as well as reduce risk of recurrence.Methods:We retrospectively assessed children with spastic cerebral palsy and flexed-knee gait pre-operatively, 1 year post-operatively, and at a minimum of 7 years post-operatively.Results:The 39 patients were a mean 9.4 ± 3.4 years at the time of surgery, 20 subjects underwent hamstring transfer, and 19 subjects had hamstring lengthening with mean follow-up 9.1 years. Passive range of motion improved initially, but regressed at long term. Dynamic minimum knee flexion in stance decreased in both groups at the first post-operative study, and was maintained at final follow-up in 64-67% of patients. There was a small increase in anterior pelvic tilt at the 1-year follow-up which subsequently decreased to less than pre-operative in the hamstring lengthening group but remained mildly increased (5°) in the hamstring transfer group at final follow-up. Success in correcting stance knee flexion of the entire group was 69% of the Gross Motor Function Classification System grades I and II and 60% of the Gross Motor Function Classification System grade III subjects. Gait profile Score and sagittal knee Gait Variable Score both showed clinically important improvement after surgery and was mostly maintained long term for both groups. Lateral hamstring lengthening was beneficial in more severe patients, with minimal risk of adverse effects.Conclusion:Hamstring surgery as part of single event multi-level surgery (SEMLS) is effective in correcting flexed-knee gait in 60%–70% of patients with minimal effect on anterior pelvic tilt. There was no added advantage to hamstring transfer. Biceps Femoris lengthening may be beneficial and without significant additional risk.Level of evidence:level III.     

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.     

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.     

Free functional rectus femoris muscle transfer for restoration of knee extension and defect coverage after trauma.

In March of 2000 and May of 2002, two patients underwent restoration of knee extension with a free neurovascular rectus femoris flap. The female patient was 10 years and the male patient 19 years old. Both patients sustained a complex trauma of the thigh with fracture of the femur and posttraumatic loss of quadriceps femoris muscles. Follow up of the patients was 51 and 27 months. After 8 months reinnervation were detected by Electromyography (EMG) in both patients and contraction became visible 2 months later. The female patient obtained a good and the male patient a very good functional result. Both patients were able to walk unaided. The authors concluded that free functional rectus femoris transfer can obtain excellent results in treating knee extension and soft-tissue defect due to trauma and loss of the quadriceps femoris muscles.     

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.     

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.     

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.     

Sagittal laxity in vivo after total knee arthroplasty

Introduction A stress arthrometry study of 77 knees undergoing total knee arthroplasty was performed to determine the difference in anteroposterior (AP) laxity between posterior cruciate ligament (PCL)-retaining (PCLR) and PCL-substituting (PCLS) prostheses using the Genesis I TKA.Materials and methods Fifty-three knees had PCLR and 24 had PCLS prostheses. The selected patients had successful arthroplasties after a minimum follow-up of 5 years. AP laxity was measured with a KT-2000 arthrometer (Medmetric, San Diego, CA, USA) using standard protocols.Results At 30° of flexion, there was no statistical difference in anterior (PCLR: 4.7 mm, PCLS: 4.5 mm), posterior (PCLR: 1.1 mm, PCLS: 0.7 mm), or total (PCLR: 5.8 mm, PCLS: 5.3 mm) displacement. At 75°, significant differences were seen in both anterior (PCLR: 3.3 mm, PCLS: 2.3 mm) and total (PCLR: 4.8 mm, PCLS: 3.4 mm) displacement (p=0.001 and p=0.009, respectively), although there was no statistical difference in posterior displacement (PCLR: 1.5 mm, PCLS: 1.1 mm).Conclusion The above values are considered the suitable degree of AP laxity in total knee arthroplasty for a satisfactory clinical outcome 5–9 years after surgery. The PCL in a PCLR prosthesis and the central tibial spine and femoral cam in a PCLS prosthesis might play comparable roles in determining the laxity in the posterior direction in these prostheses.