Chapter 41

Rectus Femoris Transfer

Jon R. Davids

DEFINITION

• The gait pattern of children with cerebral palsy (CP) is frequently disrupted by dynamic overactivity of the rectus femoris muscle.

• This disruption is characterized by delayed and diminished peak knee flexion in swing phase.

• Surgical transfer of the rectus femoris muscle to the medial hamstrings is usually performed in conjunction with other surgical procedures selected to address all elements of soft tissue and skeletal dysfunction that compromise gait in children with CP.

• This surgical strategy, termed single-event multilevel surgery (SEMLS), requires a comprehensive assessment of gait dysfunction using quantitative gait analysis.

• Proper management (surgical, orthotic, and rehabilitative) in childhood can result in an improved gait pattern that will be sustainable in the adult years.

  ANATOMY

• The rectus femoris muscle is a portion of the quadriceps muscle group, which also includes the vastus lateralis, the vastus medialis, and the vastus intermedius muscles.

• The rectus femoris muscle is the only one of the quadriceps muscle group that is considered to be biarticular, as it crosses both the hip joint and knee joint. The remaining three muscles cross only the knee joint.

  • The rectus femoris muscle is innervated by the femoral nerve. It has its origin on the anterior inferior iliac spine (direct head) and the innominate portion of the pelvis just proximal to the superior margin of the acetabulum (reflected head) and its insertion on the superior pole of the patella.

    • The rectus femoris muscle fuses with the underlying vastus intermedius muscle several centimeters proximal to the superior pole of the patella.

    • The rectus femoris muscle and the other three portions of the quadriceps muscle group envelop the patella to form the patellar tendon, which inserts on the tibial tuber-cle apophysis of the proximal tibia. It serves as a hip flexor and knee extensor.

    • The rectus femoris muscle has a relatively small physiologic cross-sectional area and a relatively large ratio of tendon length to muscle fiber length, indicating that it is designed for maximal excursion and diminished force generation.4,6

  • In normal gait, the rectus femoris muscle is active in the stance to swing phase transition, where it acts to control the magnitude of the flexion excursion of the knee as the gait velocity increases.12 It is also active at the end of the swing phase to properly position the knee in the transition from swing to stance phase.12

    • The remaining three portions of the quadriceps muscle group are active during the loading response of stance phase, where they are essential in providing shock absorption function about the knee as the limb is loaded.12

      1316

    • From a functional perspective, the quadriceps muscle group is actually two groups, the first consisting of the rectus femoris muscle and the second consisting of the tri-ceps femoris muscles (remaining three muscles).9

      PATHOGENESIS

• CP is the consequence of an injury to the immature brain that may occur before, during, or shortly after birth. The nature and location of the injury to the central nervous system (CNS) determines the components of the neuromuscular and cognitive impairments.

• Common functional deficits are related to spasticity, impaired motor control, and disrupted balance and body position senses.

• Although the injury to the CNS is not progressive, the clinical manifestations of CP change over time owing to growth and development of the musculoskeletal system.

  • The muscles typically exhibit a purely dynamic dysfunction during the first 6 years of life, characterized by a normal resting length and an exaggerated response to an applied load or stretch.

  • With time, between 6 and 10 years of age, the muscles develop a fixed or myostatic shortening, resulting in a permanent contracture.

• As such, it is best to consider CP not as a single specific disease process, but rather a clinical condition with multiple possible etiologies.17

  NATURAL HISTORY

• Ambulatory children with CP whose gait is disrupted by overactivity of the rectus femoris muscle typically walk with delayed and diminished knee flexion in swing phase. This may be associated with decreased velocity of hip flexion in the stance to swing phase transition and increased ankle plan-tarflexion in swing phase, called a “stiff” gait pattern.14,18

• These dynamic gait deviations at the hip, knee, and ankle disrupt the normal limb segment coordination that contributes to functional shortening of the limb during the swing phase of the gait cycle.16 As a result, children with CP who have a stiff gait pattern will exhibit compromised clearance of the limb in swing phase.14,18

  PATIENT HISTORY AND PHYSICAL FINDINGS

• The clinical history, as provided by the child and the parents, usually contains complaints of toe dragging, tripping, abnormal shoe wear about the toes, and inability to keep up with peers in play and sports.

• A thorough examination will include the prone rectus femoris test (also known as the Duncan-Ely test).

  • A positive slow rectus test indicates fixed shortening of the rectus femoris muscle.

  • A positive fast rectus test indicates the presence of spasticity of the rectus femoris muscle.

     

     

     

    IMAGING AND OTHER DIAGNOSTIC STUDIES

    • Radiographic imaging is not required when determining the need for transfer of the rectus femoris muscle to improve gait in children with CP.

    • Relevant data from quantitative gait analysis include tem-porospatial parameters, sagittal-plane kinematics at the knee and hip, and dynamic electromyography (EMG) of the rectus femoris muscle.

      • Gait velocity should be greater than 60% of age-matched normal.3 Children with CP who ambulate with a greatly diminished gait velocity will also exhibit disrupted sagittal-plane knee kinematics in swing phase, which will not be corrected by a rectus femoris muscle transfer.

      • Sagittal-plane knee kinematics will show decreased flexion range and velocity in the stance to swing transition, delayed and diminished peak knee flexion in swing phase, and diminished dynamic range of motion with a rounded or mounded wave form in swing phase (FIG 1A).3,10,11

      • Sagittal-plane hip kinematics during the stance to swing phase transition should be evaluated when considering surgical transfer of the rectus femoris muscle (FIG 1B).

        • A poor transition at the hip is characterized by decreased flexion range and velocity and is a contraindication to rectus femoris muscle transfer.3

        • Poor hip flexor function in the stance to swing transition will result in delayed and diminished peak knee flexion in swing phase, which will not be corrected by a rectus femoris muscle transfer.

    • Dynamic EMG of the rectus femoris muscle will show prolonged, inappropriate activity into the middle subphase of swing phase (FIG 1C).3,10,11

DIFFERENTIAL DIAGNOSIS

• Delayed and diminished peak knee flexion in swing phase may be the consequence of:

  • Inappropriate activity of the rectus femoris muscle in swing phase. Transfer of the rectus femoris muscle is indicated in this situation.

  • Diminished overall gait velocity. This circumstance is a contraindication for transfer of the rectus femoris muscle.

  • Poor hip flexor function in the stance to swing phase transition. This circumstance is a contraindication for transfer of the rectus femoris muscle.

  • Leg-length inequality, when the reference limb is relatively short or the contralateral lower extremity is relatively long. In this situation, there is less need for functional shortening of the reference limb in swing phase. This circumstance is a contraindication for transfer of the rectus femoris muscle.

    NONOPERATIVE MANAGEMENT

• In the ambulatory child with CP who is younger than 6 years, neurodevelopmental therapy and gait training may be helpful in improving the stiff gait pattern due to inappropriate activity of the rectus femoris muscle in swing phase.

• In the ambulatory child with CP who is age 6 years or older, there is no effective nonsurgical management of the stiff gait pattern.

Knee Angle

70

Flexion

40

10

Extension

-20

0

25

50

% Gait Cycle

75

100

Hip Angle

45

Flexion

25

5

Extension

-15

0

25

50

% Gait Cycle

75

100

A B

C

FIG 1 • A. Sagittal plane knee (A) and hip (B) kinematic plots of a child with a jump gait pattern. The gait cycle appears on the horizontal axis, the direction of motion on the vertical axis. The age-matched normal motion (mean ± 2 SD) appears as a purple band, and the subject’s data are indicated by a blue line. A. Kinematic indicators for transfer of the rectus femoris muscle are delayed and diminished peak knee flexion in midswing phase (circle), and decreased range and rate of knee flexion in the stance to swing transition (arrow). B. The kinematic contraindications at the hip for transfer of the rectus femoris muscle at the knee are decreased range and rate of hip flexion in the stance to swing transition (arrow). C. Dynamic electromyography (EMG) of the rectus femoris muscle in a child with CP. Three gait cycles are shown, separated by the solid black lines. The stance and swing phases of each cycle are separated by the dashed black lines. The normal timing of activation of the muscle is noted by the horizontal red lines at the bottom of the strip. The actual timing of activation of the muscle for the subject is shown by the oscillating red line at the middle of the strip. The dynamic EMG indicator for transfer of the rectus femoris muscle is prolonged and inappropriate activity in midswing phase (indicated by the circles in each gait cycle).

SURGICAL MANAGEMENT

• Achieving optimal outcomes after transfer of the rectus femoris muscle requires careful patient selection, proper surgical technique, appropriate postoperative orthotic management, and adequate rehabilitation resources (primarily physical therapy for conditioning and gait training) in the months after the surgery.

  Preoperative Planning

• Proper clinical decision making and preoperative planning for surgery to improve gait in children with CP require the integration of data from five fields—clinical history, physical examination, diagnostic imaging, quantitative gait analysis, and examination under anesthesia—in a process described as a diagnostic matrix.3

  Positioning

• The child is placed on the operating table in the supine position.

• A tourniquet is placed about the most proximal portion of the thigh, and the extremity is carefully cleansed and draped to allow adequate exposure for the surgical approach to the rectus femoris muscle.

  Approach

• The rectus femoris muscle is usually exposed via a direct anterior approach at the distal third of the thigh.

• This approach is particularly appropriate when transfer of the rectus femoris muscle and lengthening of the medical hamstring muscles are to be performed at the same time as part of SEMLS.

   

   

  TECHNIQUES

   

  SOFT TISSUE DISSECTION

  • An 8- to 12-cm incision is made over the anterior aspect of the distal third of the thigh, ending one to two fingerbreadths onto the superior pole of the patella (TECH FIG 1).

  • The dissection is carried down through the subcutaneous layers to the fascia overlying the quadriceps muscle group.

    • This fascial layer is incised for the full length of the incision, exposing the myotendinous portion of the rectus femoris muscle proximally and the superior pole of the patella distally.

       

       

       

       

      TECH FIG 1 • Medial view of the right thigh, showing the anterior skin used for exposure of the rectus femoris muscle.

       

      ISOLATION OF THE RECTUS TENDON

  • The rectus femoris muscle is identified and isolated proximally from the surrounding muscles of the quadriceps muscle group (vastus lateralis muscle laterally, vastus medialis muscle medially, and the vastus intermedius muscle deeply) (TECH FIG 2A).

    • The rectus femoris muscle is dissected from proximal to distal, freeing it completely from the surrounding quadriceps muscle group.

       

    • The dissection is carried onto the superior pole of the patella for 1 to 2 cm, and the insertion of the rectus femoris muscle onto the patella is completely released (TECH FIG 2B).

       

       

       

       

       

      A B

      TECH FIG 2 • Medial views of the right thigh (patella is to the left).

      A. Exposure of the quadriceps muscle group. The rectus femoris muscle is separated from the other muscles of the quadriceps muscle group proximally (arrow). B. Mobilization of the rectus femoris distally from its insertion on the superior pole of the patella (circle).

       

      TECHNIQUES

       

      MOBILIZATION OF THE RECTUS FEMORIS TENDON AND TUNNELING

    • A transfer stitch is placed into the distal end of the rectus femoris tendon, and the muscle–tendon unit is mobilized from distal to proximal using intermuscular dissection with scissors.

      • The rectus femoris muscle should be completely mobilized proximally to the level between the proximal and middle thirds of the thigh (TECH FIG 3A).

    • A subcutaneous tunnel is made between the proximal and medial margin of the incision used to expose the rectus femoris muscle and the distal and anterior margin of the incision used to expose the medial hamstring muscles (TECH FIG 3B).

      • This tunnel should be superficial to the quadriceps fascia and deep to the majority of the subcutaneous

        fat of the medial thigh, and expanded to a width of two fingerbreadths.

        • The rectus femoris muscle–tendon unit is passed through the subcutaneous tunnel and pulled into the incision overlying the medial hamstring muscles (TECH FIG 3C).

          • Tension is applied to the rectus femoris tendon using the transfer suture, and the line of pull of the rectus femoris muscle is assessed beneath the proximal margin of the anterior thigh incision.

          • Further proximal release may be necessary to optimize the line of pull of the rectus femoris muscle in its transferred position.

             

            A B C

            TECH FIG 3 • Medial views of the right thigh. A. Hip is to the right. Proximal mobilization of the rectus femoris. The rectus femoris muscle is manipulated using the transfer suture (dashed arrow) and released proximally using the scissors (solid arrow). B. Patella is to the left. Orientation of the transfer tunnel between the medial and anterior skin incisions (red arrow). A clamp is placed into the tunnel from distal medial to proximal anterior and used to guide the rectus femoris muscle–tendon unit to its site of transfer insertion (circle). C. The rectus femoris tendon is delivered into the medial incision (solid circle), where it will be transferred to the distal portion of the semitendinosus muscle tendon (dashed circle).

             

            TRANSFER OF THE RECTUS TENDON

          • The distal aspect of the rectus femoris tendon is transferred to the distal segment of the semitendinosus muscle tendon, which was previously released in the medial hamstring muscle lengthening (see Chap. PE-43).

            • The transfer is performed using a single interweaving of the rectus femoris and semitendinosus tendons (modified Pulvertaft technique) (TECH FIG 4).

            • The transfer is tensioned so that the muscle belly of the rectus femoris muscle is slightly tighter to palpa-tion than the muscle bellies of the remaining three muscles of the quadriceps muscle group, when the knee is held in full extension.

            • Three separate throws of a nonabsorbable suture are used to secure the transfer.

               

              TECH FIG 4 • Medial view of the right thigh (patella is to the left), showing the transfer of the rectus femoris tendon to the semitendinosus muscle tendon using a single interweaving (modified Pulvertaft technique; circle) that will be stabilized by three throws of a nonabsorbable suture.

               

               

               

               

              PEARLS AND PITFALLS

              Patient selection ■ Distal transfer of the rectus femoris muscle to the medial hamstring muscles should be

              considered only for children with delayed and diminished peak knee flexion in swing phase due to overactivity of the rectus femoris muscle. When gait velocity is diminished beyond 70% of normal, poor hip flexor function in the stance to swing transition is present, or there is an anatomic or functional leg-length inequality (reference limb short), delayed and diminished peak knee flexion in swing phase will not be improved by transfer of the rectus femoris muscle.

              • When there is spasticity of the rectus femoris muscle, and the proper kinematic and dynamic EMG indicators are present, failure to perform a rectus femoris transfer at the time of medial hamstring muscle lengthening will result in the development of a stiff gait pattern.2,20

                Release versus transfer ■ Distal transfer of the rectus femoris muscle is more effective than distal or proximal re-

                lease of the muscle at improving the timing and magnitude of peak knee flexion in swing phase.1,10,11,19

                Medial versus lateral transfer ■ Transfer to either the medial or the lateral hamstring muscle groups has no consequence (transverse-plane kinematics) on the dynamic rotational alignment of the hip or knee in stance phase.10

                Choice of medial transfer site ■ Transfer of the rectus femoris muscle to the sartorius, gracilis, semimembranosus, or semi-

                tendinosus muscles will have a comparable benefit on sagittal-plane knee kinematics in swing phase.1,7,10,11 Of the medial hamstring muscles, the semitendinosus muscle is preferred because of its myoarchitecture (long tendon length) and insertion site on the proximal tibia, which is the furthest from the knee joint center (optimizing the lever arm available for the transferred muscle).4

                Principles of tendon transfer ■ To achieve an optimal result after rectus femoris muscle transfer, the four principles of

                tendon transfer must be considered:

              • There must be adequate excursion of the transferred muscle–tendon unit. The rectus femoris muscle is a biarticular muscle and should be transferred to another biarticular muscle (such as the semitendinosus).

              • The line of pull of the transferred muscle–tendon unit should be as straight as possible. The long anterior thigh incision and intermuscular proximal release of the rectus femoris muscle must be performed. Adequate release of the rectus femoris muscle cannot be achieved through a small incision.

              • The transfer path should occur through a plane that minimizes scarring. The transfer tunnel for the rectus femoris muscle should be at the level of the subcutaneous fat, superficial to the quadriceps fascia.

              • The muscle transfer should be tensioned so the muscle belly is at a slight stretch, to optimize the length–tension relationship of the transferred muscle. The rectus femoris muscle transfer should be tensioned so the muscle is slightly tighter than the other portions of the quadriceps muscle group.

         

        POSTOPERATIVE CARE

• Transfer of the rectus femoris muscle is rarely performed in isolation for children with CP, but rather a component of SEMLS.

• If complete knee extension has been achieved after lengthening of the medial hamstring muscles and transfer of the rectus femoris muscle, then the knee is protected in a knee immobilizer after surgery. The knee immobilizer is worn full time and the child is kept non-weight bearing for 2 weeks.

• Passive knee range of motion is initiated at 1 to 2 weeks after surgery.

• Weight bearing and gait training are begun 2 to 6 weeks after surgery, depending on which other surgeries have been performed as a part of SEMLS.

• Proper rehabilitation under the guidance of an experienced physical therapist is essential, as many children with CP who have undergone simultaneous lengthening of the medial hamstring muscles and distal transfer of the rectus femoris muscle as part of SEMLS will begin to ambulate with a quadriceps avoidance gait pattern. This should be corrected by appropriate gait training early in the rehabilitation phase.

  OUTCOMES

• The goals of surgical transfer of the rectus femoris muscle are to improve the timing and magnitude of peak knee flexion in swing phase in order to correct an existing stiff gait pattern or to avoid the development of such a pattern after inappropriate isolated lengthening of the medial hamstring muscles. Improved dynamic alignment at the knee during the swing phase of the gait cycle should result in improved gait efficiency and clearance of the swing limb.

  • Improvements in swing-phase knee kinematics after rectus femoris muscle transfer have been documented at 1 year after surgery and have been shown to be maintained at 5 and 10 years of follow-up.1,5,7,8,10,11,13,15,19,21

• Distal transfer of the rectus femoris muscle to the medial hamstring muscles has been shown to be superior to proximal or distal release alone.1,10,11,19

  • The site of transfer has been shown to have no impact on the dynamic transverse-plane alignment of the hip or knee during stance phase.10

     

    COMPLICATIONS

    • Theoretical complications, such as suprapatellar rupture of the knee extensor mechanism, lack of knee extension in stance phase due to excessive tightness of the transferred rectus femoris muscle, and weakening of the quadriceps muscle group after transfer of the rectus femoris muscle, have not been reported in the literature.

    • The principal functional complication after transfer of the rectus femoris muscle is persistent quadriceps avoidance gait pattern, which may occur in children with CP who have significant spasticity and anxiety.

      • Proper rehabilitation under the direction of an experienced physical therapist is effective in managing this problem.

    • The principal cosmetic complication after transfer of the rectus femoris muscle is an unsightly scar that may develop at the incision site on the anterior aspect of the thigh. This is a consequence of the preferred incision crossing the skin lines of Langer.

      • Scar formation is minimized by proper incision wound management (pressure applied by massage) during the postoperative rehabilitation phase.

REFERENCES

1. Chambers H, Lauer A, Kaufman K, et al. Prediction of outcome after rectus femoris surgery in cerebral palsy: the role of cocontraction of the rectus femoris and vastus lateralis. J Pediatr Orthop 1998;18:703–711.

2. Damron TA, Breed AL, Cook T. Diminished knee flexion after hamstring surgery in cerebral palsy: prevalence and severity. J Pediatr Orthop 1993;13:183–191.

3. Davids JR, Ounpuu S, DeLuca PA, et al. Optimization of walking ability of children with cerebral palsy. AAOS Instr Course Lect 2004;53:511–522.

4. Delp SL, Zajac FE. Force and moment generating capacity of the lower extremity muscles before and after tendon lengthening. Clin Orthop Relat Res 1992;284:247–259.

5. Hadley N, Chambers C, Scarborough N, et al. Knee motion following multiple soft tissue releases in ambulatory patients with cerebral palsy. J Pediatr Orthop 1992;12:324–328.

6. Lieber RL. Skeletal muscle structure, function and plasticity. In: The Physiological Basis of Rehabilitation, ed 2. Baltimore: Lippincott Williams & Wilkins, 2002.

7. Miller F, Cardoso Dias R, Lipton GE, et al. The effect of rectus EMG patterns on the outcome of rectus femoris transfers. J Pediatr Orthop 1992;12:603–607.

8. Nene AV, Evans GA, Patric JH. Simultaneous multiple operations for spastic diplegia. J Bone Joint Surg Br 1993;75B:488–494.

9. Nene A, Byrne C, Hermens H. Is rectus femoris really a part of the quadriceps? Assessment of rectus femoris function during gait in able-bodied adults. Gait Posture 2004;20:1–13.

10. Ounpuu S, Muik E, Davis RB III, et al. Rectus femoris surgery in children with cerebral palsy. Part I: the effect of rectus femoris transfer location on knee motion. J Pediatr Orthop 1993;13:325–330.

11. Ounpuu S, Muik E, Davis RB III, et al. Rectus femoris surgery in children with cerebral palsy. Part II: a comparison between the effect of transfer and release of the distal rectus femoris on knee motion. J Pediatr Orthop 1993;13:331–335.

12. Perry J. Gait Analysis: Normal and Pathological Function. Thorofare, NJ: Slack Incorporated, 1992.

13. Rethelefsen S, Tolo VT, Reynolds RAK, et al. Outcome of hamstring lengthening and distal rectus femoris transfer surgery. J Pediatr Orthop B 1999;8:75–79.

14. Rodda JM, Graham HK, Carson L, et al. Sagittal gait patterns in spastic diplegia. J Bone Joint Surg Br 2004;86B:251–258.

15. Saraph V, Swick EB, Swick G, et al. Multilevel surgery in spastic diplegia: evaluation by physical examination and gait analysis in 25 children. J Pediatr Orthop 2002;22:150–157.

16. Saunders JR, Inman VT, Eberhart HD. The major determinants in normal and pathological gait. J Bone Joint Surg Am 1953;35A:543–558.

17. Stanley F, Blair E, Alberman E. Cerebral Palsies: Epidemiology and Causal Pathways. Clinics in Developmental Medicine 2000, no. 51. London: MacKeith Press, 2000.

18. Sutherland DH, Davids JR. Common gait abnormalities of the knee in cerebral palsy. Clin Orthop Relat Res 1993;288:139–147.

19. Sutherland DH, Santi M, Abel MF. Treatment of stiff-knee gait in cerebral palsy; a comparison of distal rectus femoris transfer versus proximal rectus release. J Pediatr Orthop 1990;10:433–442.

20. Thometz J, Simon S, Rosenthal R. The effect on gait of lengthening of the medial hamstrings in cerebral palsy. J Bone Joint Surg Am 1989;71A:345–353.

21. Zwick EB, Saraph V, Linhart WE, et al. Propulsive function during gait in diplegic children: evaluation after surgery for gait improvement. J Pediatr Orthop B 2001;10:226–233.