Genu Valgum (knocked knees)

Introduction

Genu valgum is a normal physiologic process in children
- therefore it is critical to differentiate between a physiologic and pathologic process
Epidemiology
- distal femur is the most common location of primary pathologic genu valgum but can arise from tibia
Etiologies
- bilateral genu valgum
  - physiologic
  - renal osteodystrophy (renal rickets)
  - skeletal dysplasia
    - Morquio syndrome
    - spondyloepiphyseal dysplasia
    - chondroctodermal dysplasia
- unilateral genu valgum
  - physeal injury from trauma, infection, or vascular insult
  - proximal metaphyseal tibia fracture
  - benign tumors
    - fibrous dysplasia
    - osteochondromas
    - Ollier's disease
Prognosis
- the threshold of deformity that leads to future degenerative changes is unknown
- deformity after a proximal metaphyseal tibia fracture (Cozen) should be observed, as it almost always remodels

Anatomy

Normal physiologic process of genu valgum
- between 3-4 years of age children have up to 20 degrees of genu valgum
- genu valgum rarely worsens after age 7
- after age 7 valgus should not be worse than 12 degrees of genu valgum
- after age 7 the intermalleolar distance should be <8 cm

Treatment

Nonoperative
- observation
  - indications
    - first line of treatment
    - genu valgum <15 degrees in a child <6 years of age
- bracing
  - indications
    - rarely used
      - ineffective in pathologic genu valgum and unnecessary in physiologic genu valgum
Operative
- hemiepiphysiodesis or physeal tethering (staples, screws, or plate/screws) of medial side
  - indications
    - > 15-20° of valgus in a patient <10 years of age
    - if line drawn from center of femoral head to center of ankle falls in lateral quadrant of tibial plateau in patient > 10 yrs of age
  - technique
    - to avoid physeal injury place them extraperiosteally
    - to avoid overcorrection follow patients often
    - growth begins within 24 months after removal of the tether
- distal femoral varus osteotomy
  - indications
    - insufficient remaining growth for hemiepiphysiodesis
  - complications
    - peroneal nerve injury
      - perform a peroneal nerve release prior to surgery
    - gradually correct the deformity
    - utilize a closing wedge technique

TAG

(OBQ11.3) An 18-year-old girl presents with a deformity of the left leg that limits her ability to play basketball and volleyball. She reports pain along the lateral joint line with vigorous activity. A clinical image of the left leg in the supine position is shown in Figure A. A standing alignment radiograph is shown in Figure B with the mechanical lateral distal femoral angle measured at 73° (mLDFA 88°, range 85°-90°), an mechanical medial proximal tibial angle of 87° (mMPTA 87°, range 85°-90°), and a tibial femoral angle of 25°(range 5°-10°). Which of the following is the most appropriate surgical treatment? Topic

Review Topic

FIGURES: A

1. Lateral closing wedge proximal femoral osteotomy with medial opening wedge tibial osteotomy
2. Lateral closing wedge tibial osteotomy
3. Medial opening wedge femoral osteotomy
4. Medial closing wedge tibial osteotomy
5. Medial closing wedge femoral osteotomy

PREFERRED RESPONSE ▶

DISCUSSION: Genu valgum in the skeletally mature individual is most appropriately treated with a varus-producing distal femoral osteotomy. If the deformity were to be addressed with a medial closing wedge tibial osteotomy an oblique joint line would be maintained. Varus and valgus can be determined by measuring the lateral distal femoral angle (normal=88 deg), medial proximal tibial angle (normal=87 deg), or the tibiofemoral angle (normal=5-10 degrees). Figure B shows that the the lateral distal femoral angle is less than 87 degrees and thus the femur should be addressed with the deformity correction.

Tetsworth and Paley present a Level 4 review of 28 limbs that underwent external fixation for deformity correction. They measured mechanical axis deviation (MAD) and mechanical tibiofemoral angle (mTFA) pre and postoperatively in these patients and found external fixation to be a reliable method of deformity correcion.

Paley presents a Level 5 review discussing the spectrum of lower extremity angular and rotational deformities and their treatments. He cites that the work of Gavril Abramovich Ilizarov in the field of external fixation has been instrumental in advancing the field of deformity correction and the magnitude of the deformity is no longer an obstacle with gradual correction of bone or joint deformities.

Illustration A shows a schematic of a distal femoral osteotomy. Illustration B is a schematic of how addressing genu valgum by way of a tibial osteotomy would create the unwanted result of an oblique joint line.

Illustrations: A

REFERENCES:

1. Paley D. Correction of limb deformities in the 21st century. J Pediatr Orthop. 2000 May-Jun;20(3):279-81. PMID:10823589 (Link to Abstract)

2. Tetsworth KD, Paley D. Accuracy of correction of complex lower-extremity deformities by the Ilizarov method. Clin Orthop Relat Res. 1994 Apr;(301):102-10 PMID:8156660 (Link to Abstract)

Question Authors:

Michael Hughes MD, John Badylak MD, Ben Taylor MD,

Please Rate Educational Value!

4.0

Average 4.0 of 7 Ratings

TAG

(OBQ11.13) A 12-year-old skeletally immature female presents with a several year history of bilateral knee pain and lower extremity deformity with her knees rubbing together while she runs. Her medical history is positive for asthma and eczema. She denies constitutional symptoms. She is neurovascularly intact in the bilateral lower extremities. A standing alignment radiograph is shown in Figure A. Which of the following treatment options is most appropriate? Topic

Review Topic

FIGURES: A

1. Hip-knee-ankle-foot orthotic (HKAFO)
2. Distal femoral osteotomy with plate fixation of bilateral distal femurs
3. Temporary hemiepiphysiodesis across the bilateral medial distal femoral growth plates
4. Temporary hemiepiphysiodesis across the right medial distal femoral growth plate
5. Temporary lateral hemiepiphysiodesis of the bilateral distal femoral growth plates

PREFERRED RESPONSE ▶

DISCUSSION: The clinical presentation is consistent with severe bilateral genu valgum in a skeletally immature patient. Temporary hemiepiphysiodesis across the bilateral medial distal femoral growth plates is the most appropriate treatment.

Temporary hemiepiphysiodesis, or temporary physeal tethering using staples or tension plates, can be utilized to redirect physeal growth depending on the amount of growth calculated to remain for the child. Surgical correction is warranted if a mechanical axis line drawn from the center of the head of the femur to the center of the ankle falls in at least the outer 25% of the tibial plateau in children older than 10 years.

Wiemann et al. present a Level 4 review of 63 patients that underwent either physeal stapling or tension "8-plate" hemiepiphysiodesis. They found that the tension "8-plate"(as shown in Illustration A) is as effective as staple hemiepiphysiodesis for correction of angular deformity in terms of the rate of correction and associated complications.

Stevens presents Level 4 evidence of 34 patients that underwent nonlocking extraperiosteal "8-plate" tethering. He observed that the rate of correction was approximately 30% more rapid than noted with stapling, and that only 4 patients needed revision alignment surgery for rebound deformity.

Schroerlucke et al. report a Level 4 study of 31 patients that underwent "8-plate" tethering. They found that implant failure occurred in 8 (26%) of the proximal tibia constructs. All of these failures happened in patients with Blount's disease and involved breakage of the tibial metaphyseal screw.

Figure A displays a radiograph of bilateral genu valgum (anatomic LDFA= 80 degrees)in a skeletally immature individual. Illustration A is an example of a lateral tension band plate or "8 plate". Illustration B demonstrates the complication of screw breakage during hemiepiphysiodesis. Illustration C demonstrates a postoperative extremity alignment radiograph showing medial tension band plate tethering and correction of genu valgum.

Incorrect Answers:
Answer 1: Bracing plays no role in the treatment of severe bilateral genu valgum.
Answer 2: Osteotomy is considered once the child is skeletally mature or not enough growth remains for guided-growth.
Answer 4: The patient has bilateral disease, so a unilateral correction is not sufficient.
Answer 5: This will worsen her deformity.

Illustrations: A

REFERENCES:

1. Wiemann JM 4th, Tryon C, Szalay EA. Physeal stapling versus 8-plate hemiepiphysiodesis for guided correction of angular deformity about the knee. J Pediatr Orthop. 2009 Jul-Aug;29(5):481-5. PMID:19568021 (Link to Abstract)

2. Stevens PM. Guided growth for angular correction: a preliminary series using a tension band plate. J Pediatr Orthop. 2007 Apr-May;27(3):253-9. PMID:17414005 (Link to Abstract)

3. Schroerlucke S, Bertrand S, Clapp J, Bundy J, Gregg FO. Failure of Orthofix eight-plate for the treatment of Blount disease. J Pediatr Orthop. 2009 Jan-Feb;29(1):57-60. PMID:19098648 (Link to Abstract)

Question Authors:

Michael Hughes MD, John Badylak MD, Eric Shirley MD,

Please Rate Educational Value!

4.0

Average 4.0 of 8 Ratings

Level of Evidence 4 (Case Series)

Schroerlucke S, Bertrand S, Clapp J, Bundy J, Gregg FO. Failure of Orthofix eight-plate for the treatment of Blount disease. J Pediatr Orthop. 2009 Jan-Feb;29(1):57-60. PMID:19098648 (Link to Abstract)
Stevens PM. Guided growth for angular correction: a preliminary series using a tension band plate. J Pediatr Orthop. 2007 Apr-May;27(3):253-9. PMID:17414005 (Link to Abstract)
Tetsworth KD, Paley D. Accuracy of correction of complex lower-extremity deformities by the Ilizarov method. Clin Orthop Relat Res. 1994 Apr;(301):102-10 PMID:8156660 (Link to Abstract)
Wiemann JM 4th, Tryon C, Szalay EA. Physeal stapling versus 8-plate hemiepiphysiodesis for guided correction of angular deformity about the knee. J Pediatr Orthop. 2009 Jul-Aug;29(5):481-5. PMID:19568021 (Link to Abstract)

Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions, Personal Observations, and Biomechanic Studies)

Paley D. Correction of limb deformities in the 21st century. J Pediatr Orthop. 2000 May-Jun;20(3):279-81. PMID:10823589 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

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