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Pediatric Fixed Knee Flexion Deformities Treatment & Management

  • Author: Peter M Stevens, MD; Chief Editor: Dennis P Grogan, MD  more...
 
Updated: Aug 16, 2013
 

Medical Therapy

Medical therapy for fixed knee flexion deformity (FKFD) usually consists of Botox injections in the hamstrings or baclofen administered orally or through an intrathecal pump (for cerebral palsy). This is only useful for the dynamic component of crouch gait; it may be an adjunct to osteotomy or guided growth. The patient is often working with a physical therapist on hamstring stretching, quadriceps strengthening, and gait training. This is suitable for younger patients, but after the age of 10 years, deformities are likely to progress despite concerted efforts to the contrary.

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Surgical Therapy

Posterior capsulotomy/hamstring recession

For flexion contracture, spasticity management (Bo For flexion contracture, spasticity management (Botox/phenol/baclofen) or hamstring recession may offer some improvement, but these measures cannot overcome fixed knee flexion deformity (FKFD).

This relatively invasive soft tissue procedure poses some risks to the posterior neurovascular structures and requires immobilization with braces, casts, or frames.

Osteotomy

Supracondylar extension osteotomy of the femora has a long track record and is the default mode for many surgeons. Unfortunately, there are associated drawbacks, not the least of which is recurrence with growth, thus mitigating the temporary benefit of this maximally invasive treatment. The varied techniques, tricks, results, and complications have been well described in standard textbooks and journals.

Starting at age 4, this patient subsequently under Starting at age 4, this patient subsequently underwent bilateral extension osteotomies 4 times, with recurrence each time as expected. Perhaps this sequence could have been abbreviated with guided growth, which, even if repeated, requires no casts or delay in weight bearing.

Frame distraction

With or without soft tissue release, some authors favor frame distraction as a means of gradual correction of fixed knee flexion deformity (FKFD). However, the bilateral nature of these problems makes this method relatively expensive and unwieldy. Furthermore, even with protracted bracing, recurrence is relatively common.

This girl born with a teratologic knee flexion def This girl born with a teratologic knee flexion deformity and absent quadriceps had previous posterior capsulotomy, supracondylar osteotomy, and attempted stapling. Subsequently, she had a spatial frame applied to gradually extend the ankylosed knee; however, she fell and sustained a Salter I fracture of the proximal tibia.

Guided growth

Guided growth is a new concept that consists of anterior hemiepiphysiodesis of the distal femora. Originally accomplished with staples, it became apparent that some children were relatively small for the Blount staples.[20] These rigid devices would occasionally migrate or permit relatively slow correction. Using a pair of 8-plates as an alternative has resolved the problem of hardware migration and enabled more rapid correction. The titanium plates, though intracapsular, are nonarticular, being placed medial and lateral to the patellofemoral sulcus. Thus, they are well tolerated, even by young children.

Guided growth permits one to address the FKFD at o Guided growth permits one to address the FKFD at or close to the level of the CORA (center of rotational axis of deformity). This is efficient and prevents the need for translocation, such as is required in an osteotomy. The gradual correction poses no risk to the neurovascular structures.
For FKFD, an 8-plate is placed on either side of t For FKFD, an 8-plate is placed on either side of the patellofemoral sulcus, through a small arthrotomy. Though intracapsular, the plates are nonarticular; synovitis has not been observed.
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Preoperative Details

Guided growth

If one elects to employ guided growth, it is important to ascertain whether the distal femoral physes are open and whether there is, ideally, 12 months or more of predicted growth remaining. The decision to undertake concomitant multilevel reconstructive procedures, including hamstring recession for dynamic contracture, is left to the discretion of the surgeon.

Note, however, that as fixed knee flexion deformity (FKFD) gradually corrects, there may be beneficial effects upon the hip, spine, and ankle. Therefore, it may be wise to await full knee extension and address residual deformities at the time of 8-plate removal.

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Intraoperative Details

Guided growth

With the C-arm in the lateral, horizontal position With the C-arm in the lateral, horizontal position, the physis is localized. A Keith needle is placed in the physis, and two 1.6-mm guide pins are inserted: one medial and one lateral to the sulcus. The cannulated 4.5-mm screws are then inserted. They need not be parallel, but they should not transgress the physis, joint, or posterior cortex.

See the list below:

  • Supine position with knee flexed on bolster
  • Tourniquet control
  • Image intensifier: parked in cross-table, horizontal position
  • Two incisions (3 cm long), medial and lateral to the patella
  • Open capsule and synovium
  • Place Keith or similar needle (sequentially) into anteromedial and anterolateral physis
  • Apply 8-plate (Orthofix): usually 16-mm size
  • Introduce 1.6 guide pins: first the epiphyseal, then metaphyseal
  • Pins need not be parallel but should avoid the physis and joint
  • Predrill cortex (5-mm depth)
  • Insert the 4.5-mm titanium, self-tapping, cannulated screws (24- or 32-mm size)
  • Soft dressing
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Postoperative Details

See the list below:

  • Typically, either as outpatient or with an overnight stay
  • Immediate range of motion and weight bearing are encouraged
  • Resume bracing and physical therapy as indicated
  • One study found that in children with cerebral palsy, the pain pump is effective in postoperative pain management after lower extremity orthopedic procedures. [23]
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Follow-up

See the list below:

  • At 3-month intervals, to measure fixed knee flexion deformity (FKFD) and assess gait
  • Functional limb length and stride length will improve as the knee straightens
  • Remove plates if/when knee is fully extended (avoid recurvatum)
  • Reinsert plates as needed if FKFD recurs with growth
  • Follow-up until skeletal maturity
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Complications

Posterior capsulotomy

See the list below:

  • Neurovascular damage
  • Undercorrection or overcorrection (PCL release)
  • Recurrent deformity

Supracondylar osteotomy

See the list below:

  • Neurovascular damage
  • Loss of fixation
  • Undercorrection or overcorrection: 2 º varus or valgus
  • Pathologic fracture
  • Recurrent deformity

Frame distraction

See the list below:

  • Pin tract problems
  • Infection
  • Recurrent deformity

Guided growth

See the list below:

  • Undercorrection: if not enough growth remaining
  • Overcorrection: if lost to follow-up
  • Recurrent deformity
  • Premature growth arrest will not occur if the periosteum is protected

When compared to the other options, guided growth has far fewer risks and complications and is more cost-effective. The procedure is well tolerated, and the recovery is rapid. It may be repeated as necessary and is readily combined with other procedures as indicated.

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Outcome and Prognosis

The natural history of fixed knee flexion deformity (FKFD) is insidious progression despite bracing, therapy, and even repeated surgical intervention. The goal of treatment is to maintain standing and, hopefully, walking ability while minimizing complications and encumbrance.

One must weigh the risk-to-benefit ratio of any invasive treatment, recognizing that it may need to be repeated. Like so many conditions, it is appealing to consider early intervention, before the onset of secondary problems such as patellar migration or fragmentation. With this in mind, repeated guided growth may be the pathway of least harm and maximum benefit.

In a clinical series of 18 patients with 29 cases of FKFD, the rate of correction was 1.74 º per month; the highest rate noted was nearly 4 º per month. Without the need for immobilization, these children have experienced rapid recovery with minimal setbacks from the surgery.

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Future and Controversies

There may eventually be other methods of temporary physeal restraint. The allure of biodegradable implants or remote-control techniques by electronic or radiofrequency methodology will undoubtedly spur further research.

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Contributor Information and Disclosures
Author

Peter M Stevens, MD Professor, Director of Pediatric Orthopedic Fellowship Program, Department of Orthopedics, University of Utah School of Medicine

Peter M Stevens, MD is a member of the following medical societies: Pediatric Orthopaedic Society of North America, Alpha Omega Alpha, American Academy of Orthopaedic Surgeons, American Orthopaedic Association

Disclosure: Received royalty from Orthofix Inc for independent contractor; Received royalty from Orthopediatrics, Inc for independent contractor; Received honoraria from Orthopediatrics, Inc for speaking and teaching.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Paul E Di Cesare, MD 

Paul E Di Cesare, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American College of Surgeons

Disclosure: Nothing to disclose.

Chief Editor

Dennis P Grogan, MD Clinical Professor (Retired), Department of Orthopedic Surgery, University of South Florida College of Medicine; Orthopedic Surgeon, Department of Orthopedic Surgery, Shriners Hospital for Children of Tampa

Dennis P Grogan, MD is a member of the following medical societies: American Medical Association, American Orthopaedic Association, Scoliosis Research Society, Irish American Orthopaedic Society, Pediatric Orthopaedic Society of North America, American Academy of Orthopaedic Surgeons, American Orthopaedic Foot and Ankle Society, Eastern Orthopaedic Association

Disclosure: Nothing to disclose.

References
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The lateral radiograph best demonstrates the open physes and the stigmata of chronic fixed knee flexion deformity (FKFD). This patient has avulsion "fractures" of the superior pole of the patella and of the tibial tubercle.
For flexion contracture, spasticity management (Botox/phenol/baclofen) or hamstring recession may offer some improvement, but these measures cannot overcome fixed knee flexion deformity (FKFD).
A posterior capsulotomy with or without PCL release can address fixed knee flexion deformity (FKFD), albeit with some risks, including neurovascular stretch injuries. Even with prolonged bracing following cast or frame removal, recurrent deformities are common.
Locking KAFO may support the patient for standing but cannot adequately address FKFD. When the deformity exceeds 20º, braces are poorly tolerated.
This child with arthrogryposis underwent unsuccessful posterior capsulotomies at age 3.
Starting at age 4, this patient subsequently underwent bilateral extension osteotomies 4 times, with recurrence each time as expected. Perhaps this sequence could have been abbreviated with guided growth, which, even if repeated, requires no casts or delay in weight bearing.
This ambulatory 15-year-old boy with arthrogryposis has never had an osteotomy; he was managed with stapling, followed by 8-plates, when he developed a recurrence. He has full extension on the right and 7º residual FKFD on the left. The 8-plates are still in situ (on the left) pending further growth.
The efficacy of floor reaction braces is compromised in the presence of FKFD. However, they may be continued following guided growth, pending correction, whereupon bracing may be unnecessary, provided the quadriceps are sufficiently strong.
Normal sagittal alignment permits the knee to lock in full extension, aided by powerful quadriceps and an intact extensor mechanism. The ground reaction force passes anterior to the "center of rotation" of the knee, while the PCL, posterior capsule, hamstrings, and gastrocnemius provide a tension band effect.
Fixed knee flexion deformity (FKFD). The knee is chronically bent, obligating the patient to walk with a crouch gait. The ground reaction force passes posterior to the center of rotation of the knee, where it overcomes the resistance of the weakened extensor mechanism. Secondary effects, including patella alta and fragmentation, are relatively common and painful.
(Images 11 through 15) This 5-year-old boy presented with a congenital knee flexion deformity. His only prior surgery was a Symes disarticulation for fibular absence and a rigid teratologic foot deformity. He was ambulatory in a prosthesis.
(Images 11 through 15) This patient underwent a supracondylar extension osteotomy of the femur.
(Images 11 through 15) Because of a relatively rapid recurrence of FKFD, this patient underwent anterior stapling of the femur; unfortunately, the staples migrated, but the physis is still open.
(Images 11 through 15) The staples in this patient were retrieved and replaced with a pair of 8-plates.
(Images 11 through 15) If we could turn back the clock, perhaps guided growth would have been sufficient to correct the problem in this patient, without an osteotomy or cast. The effective gain in limb length would occur gradually, without risk to the neurovascular structures.
This girl born with a teratologic knee flexion deformity and absent quadriceps had previous posterior capsulotomy, supracondylar osteotomy, and attempted stapling. Subsequently, she had a spatial frame applied to gradually extend the ankylosed knee; however, she fell and sustained a Salter I fracture of the proximal tibia.
Guided growth permits one to address the FKFD at or close to the level of the CORA (center of rotational axis of deformity). This is efficient and prevents the need for translocation, such as is required in an osteotomy. The gradual correction poses no risk to the neurovascular structures.
For FKFD, an 8-plate is placed on either side of the patellofemoral sulcus, through a small arthrotomy. Though intracapsular, the plates are nonarticular; synovitis has not been observed.
Depending on the etiology and the growth rate of the individual child, correction occurs fairly rapidly.
With the C-arm in the lateral, horizontal position, the physis is localized. A Keith needle is placed in the physis, and two 1.6-mm guide pins are inserted: one medial and one lateral to the sulcus. The cannulated 4.5-mm screws are then inserted. They need not be parallel, but they should not transgress the physis, joint, or posterior cortex.
(Images 21 and 22) This 4-year-old girl, born with congenital lateral dislocation of the patella compounding FKFD, underwent a posterior capsulotomy and patellar relocation with quadricepsplasty at age 2. By age 4, she had an oblique plane FKFD of 50º with 25º valgus. She had placement of a single anteromedial eight-plate. Eighteen months later, the valgus had corrected and the residual FKFD was 24º.
(Images 21 and 22) This patient underwent the addition of an anterolateral 8-plate to avoid varus and assist with correction of the residual FKFD.
This 12-year-old boy with spina bifida had previous stapling. It was felt that, with wide open physes, he would be better served by exchanging the loose staples for 8-plates rather than resort to an osteotomy.
(Images 24 and 25) A 12-year-old girl with evolving FKFD and patella alta, refractory to Botox, serial casts, therapy, and bracing.
(Images 24 and 25) This patient underwent bilateral supracondylar extension osteotomies with patellar tendon advancement. Because of limited space and compromised bone stock, fixation was lost on the left, and she presented with increased deformity. A revision osteotomy was required.
(Images 26 and 27) This patient has symptomatic and painful crouch gait due to FKFD.
(Images 26 and 27) This patient underwent guided growth with 8-plates and no "down time"; his FKFD corrected nicely during the ensuing 12 months, whereupon the plates were removed.
 
 
 
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