What is the treatment approach for genu valgum (knock knees)?

Genu Valgum: Pathophysiology and Treatment

For patients with genu valgum (knock knees), treatment should be guided by the severity of deformity, age of the patient, and functional impairment, with surgical intervention recommended for severe cases that persist despite optimized medical treatment or cause symptoms interfering with function. 1

Pathophysiology

Genu valgum is characterized by a medial angulation of the lower leg in relation to the thigh, resulting in the knees being abnormally close together while the ankles remain separated. The condition can arise from various causes:

• Idiopathic or associated with obesity (most common etiology) 2
• Physeal trauma (often unrecognized) 3
• Iatrogenic injury, infection, tumor, or skeletal dysplasia 3
• Ligamentous laxity contributing to the deformity 4

The pathophysiology involves both osseous and ligamentous components that must be recognized for successful treatment. The deformity can lead to:

• Abnormal mechanical loading of the knee joint 3
• Altered gait patterns 4
• Pain and functional limitations 4
• Potential for progressive joint damage if left untreated 1

Assessment and Diagnosis

Assessment should include:

• Clinical evaluation of limb alignment and intermalleolar distance 2
• Radiographic assessment with weight-bearing full-length lower extremity radiographs to measure:
  • Anatomical femorotibial angle
  • Mechanical lateral distal femoral angle
  • Medial proximal tibial angle 2
• Evaluation of functional impairment and symptoms 1

Treatment Approach

Conservative Management

1. Physical Therapy and Exercise

   • Strengthening exercises for quadriceps muscles are strongly recommended for improving knee alignment and function 1
   • Both strengthening and aerobic fitness training have shown benefits for pain and function 1

2. Orthotic Interventions

   • Custom-molded foot orthoses may improve distal alignment at feet and ankles and secondarily decrease genu valgum 1
   • Taller orthotic intervention with ankle-foot orthoses may be recommended for more severe malalignment or instability 1
   • Lateral wedge insoles are NOT recommended for patients with symptomatic medial compartmental knee osteoarthritis (which may develop secondary to genu valgum) 1

3. Bracing

   • Evidence for braces with varus-directing force for lateral unicompartmental knee issues (related to genu valgum) is inconclusive 1

Surgical Management

Surgical intervention should be considered when:

1. Indications for Surgery

   • Deformity persists despite optimized medical treatment 1
   • Presence of symptoms interfering with function 1
   • Radiographic deformity (Mechanical Axis Deviation Zone 2 or greater) 1

2. Age Considerations

   • Guided growth techniques must be performed at least 2-3 years before skeletal maturity (age 14 in girls and age 16 in boys) 1
   • Complications associated with osteotomy are reduced when surgery is performed later in childhood or after skeletal maturity 1

3. Surgical Options

   a. Guided Growth Techniques (Temporary Hemiepiphysiodesis)

   • Uses eight-Plates implanted on the distal medial femur and/or proximal medial tibia 2
   • Indicated for growing children (at least 2-3 years before skeletal maturity) 1
   • Advantages: gentle, simple, effective procedure with low complication rates (2.8%) 2
   • Limitations: provides only uniplanar coronal correction without addressing tibial torsion 1
   • Both varus and valgus deformities correct readily, though genu varum might respond less in adolescents 1

   b. Osteotomy

   • Performed at sites of major deformity with correction in all three planes 1
   • Can result in acute correction with internal fixation or gradual correction using external fixation 1
   • Associated with notable rates of recurrence and complications (57% of patients experienced at least one complication in one study) 1
   • For genu recurvatum-valgus deformities, opening-wedge proximal tibial osteotomy along the true deformity plane is reliable for lesser-magnitude deformities 3, 5

   c. External Fixation

   • Gradual correction using circular external fixation is considered when:
     • Magnitude of correction is greater than 25° 3
     • Limb shortening and/or multiplanar deformity is present 3

Post-Treatment Monitoring

• Regular clinical and functional assessments should be made following surgery 1
• Radiographic assessment at 12 months post-surgery, or earlier if deformity worsens 1
• Further assessments should follow intermittently until skeletal maturity 1
• Slight overcorrection is desirable due to the rebound phenomenon, especially in young patients with high growth potential and risk groups such as obese children 2

Special Considerations

• In adolescents older than 14 years with low growth potential, the indication for guided growth techniques should be strictly reviewed due to limited correction potential 2
• Emergency surgical treatment such as fracture fixation should occur when necessary 1
• Functional assessment should be performed according to standardized tools such as the Pediatric Outcomes Data Collection Instrument (PODCI) 1
• As patients transition to adult services, a full orthopedic clinical and radiographic assessment enables definition of any residual deformity 1