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Genu Varum

Genu varum is a deformation of the knee joint Knee joint The knee joint is made up of the articulations between the femur, tibia, and patella bones, and is one of the largest and most complex joints of the human body. The knee is classified as a synovial hinge joint, which primarily allows for flexion and extension with a more limited degree of translation and rotation. Knee Joint: Anatomy(s) that creates angulation Angulation Buckle or Torus Fracture of the lower limb(s) away from the midline in the coronal Coronal Computed Tomography (CT) plane. Children ages 1–5 years are commonly affected. Many cases of genu varum are physiologic and will resolve with further growth. However, it is critical to differentiate between normal physiologic changes and pathologic disorders, as pathologic cases can have serious long-term consequences if not corrected. Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor includes characteristic outward bowing of the lower limbs accompanied by gait Gait Manner or style of walking. Neurological Examination disturbances. Diagnosis is clinical but may require support with diagnostic imaging. Management is often supportive but may require surgical intervention.

Last updated: 4 Apr, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

  • Genu varum is an angular deformity Deformity Examination of the Upper Limbs of the knee:
  • Common for toddlers to have physiologic genu varum: 
    • Common up to 3 years old
    • Generally symmetric and pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways-free
    • Associated with tripping/intoeing
    • Generally self-correcting
    • Can be the result of intrauterine positioning
  • Pathologic genu varum: varus deformation that persists beyond the expected time frame because of an underlying condition:
    • Blount disease
    • Rickets Rickets Disorders caused by interruption of bone mineralization manifesting as osteomalacia in adults and characteristic deformities in infancy and childhood due to disturbances in normal bone formation. The mineralization process may be interrupted by disruption of vitamin d; phosphorus; or calcium homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances. Osteomalacia and Rickets
    • Skeletal dysplasia Dysplasia Cellular Adaptation
  • Colloquially known as “bow-legged,” genu varum is the Latin-derived term to describe the deformity Deformity Examination of the Upper Limbs 

Classification

  • Bilateral
  • Unilateral (e.g., Blount disease)
  • Distinguished from genu valgum Genu valgum Genu valgum is a deformation of the knee joint(s) that creates angulation of the lower limb(s) toward the midline in the coronal plane. Children ages 1-5 years are commonly affected. Genu Valgum by the direction of angular deformity Deformity Examination of the Upper Limbs relative to the midline:
    • Genu varum: apex displaced away from the midline
    • Genu valgum Genu valgum Genu valgum is a deformation of the knee joint(s) that creates angulation of the lower limb(s) toward the midline in the coronal plane. Children ages 1-5 years are commonly affected. Genu Valgum: apex displaced toward the midline
Genu varum and valgum

Genu varum and genu valgum Genu valgum Genu valgum is a deformation of the knee joint(s) that creates angulation of the lower limb(s) toward the midline in the coronal plane. Children ages 1-5 years are commonly affected. Genu Valgum: note the difference in angulation Angulation Buckle or Torus Fracture in the coronal Coronal Computed Tomography (CT) plane.

Image by Lecturio. License: CC BY-NC-SA 4.0

Epidemiology

  • Seen in children 2–5 years of age 
  • Present in 8% of schoolchildren 
  • More common among overweight or obese schoolchildren
  • More common in countries where malnutrition Malnutrition Malnutrition is a clinical state caused by an imbalance or deficiency of calories and/or micronutrients and macronutrients. The 2 main manifestations of acute severe malnutrition are marasmus (total caloric insufficiency) and kwashiorkor (protein malnutrition with characteristic edema). Malnutrition in children in resource-limited countries is usually seen

Etiology

  • Metabolic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types diseases:  
    • Rickets Rickets Disorders caused by interruption of bone mineralization manifesting as osteomalacia in adults and characteristic deformities in infancy and childhood due to disturbances in normal bone formation. The mineralization process may be interrupted by disruption of vitamin d; phosphorus; or calcium homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances. Osteomalacia and Rickets
    • Hyperparathyroidism Hyperparathyroidism Hyperparathyroidism is a condition associated with elevated blood levels of parathyroid hormone (PTH). Depending on the pathogenesis of this condition, hyperparathyroidism can be defined as primary, secondary or tertiary. Hyperparathyroidism
  • Asymmetric epiphysiodesis: 
    • Blount disease ( tibia Tibia The second longest bone of the skeleton. It is located on the medial side of the lower leg, articulating with the fibula laterally, the talus distally, and the femur proximally. Knee Joint: Anatomy vara): 
      • Infantile
      • Juvenile
      • Adolescent
    • Trauma
    • Infection
    • Tumors
  • Skeletal dysplasias: 
  • Digestive disorders: 
    • Celiac sprue
    • Inflammatory bowel disease
  • Disorder of bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types/ connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology fragility: 
    • Osteogenesis imperfecta Osteogenesis imperfecta Osteogenesis imperfecta (OI), or “brittle bone disease,” is a rare genetic connective tissue disorder characterized by severe bone fragility. Although OI is considered a single disease, OI includes over 16 genotypes and clinical phenotypes with differing symptom severity. Osteogenesis Imperfecta
    • Ehlers–Danlos syndrome

Pathophysiology

  • Normal alignment:
    • Lower-extremity lengths are equal.
    • Mechanical axis Axis The second cervical vertebra. Vertebral Column: Anatomy bisects the knee in the anatomical position.
    • Balanced load on the medial and lateral compartments of the knee
    • Balanced load on the collateral ligaments
    • Patella Patella The flat, triangular bone situated at the anterior part of the knee. Knee Joint: Anatomy centered in the femoral sulcus
  • Genu varum defined by medial displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms of the mechanical axis Axis The second cervical vertebra. Vertebral Column: Anatomy:
    • Medial femoral condyle and the medial plateau Plateau Cardiac Physiology of the tibia Tibia The second longest bone of the skeleton. It is located on the medial side of the lower leg, articulating with the fibula laterally, the talus distally, and the femur proximally. Knee Joint: Anatomy subjected to pathologic loading
    • Leads to inhibition of normal ossification Ossification The process of bone formation. Histogenesis of bone including ossification. Bones: Development and Ossification of the epiphysis Epiphysis The head of a long bone that is separated from the shaft by the epiphyseal plate until bone growth stops. At that time, the plate disappears and the head and shaft are united. Bones: Structure and Types
    • Lateral collateral ligaments become stretched.
    • Severe deformity Deformity Examination of the Upper Limbs leads to: 
      • Knee pain Knee Pain Knee pain is a common presentation to primary care physicians. The diagnosis can be challenging as the pain may arise from the joint, surrounding tissues, or referred to the joint from distant structures. The differential diagnosis of knee pain is broad and categorizing the various diagnoses related to the timing (acute or chronic) is useful. Knee Pain 
      • Lateral thrust during gait Gait Manner or style of walking. Neurological Examination
      • Characteristic intoeing
      • Patient walks with a waddling gait Gait Manner or style of walking. Neurological Examination
    • Long-term effects:
      • Medial meniscal tears
      • Tibiofemoral subluxation Subluxation Radial Head Subluxation (Nursemaid’s Elbow)
      • Articular cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage: Histology attrition
      • Arthrosis of medial compartment of the knee

Clinical Presentation

History

Parents describe a bow-legged appearance and abnormal gait Gait Manner or style of walking. Neurological Examination.

Physical examination

  • Bowing of the legs away from the midline when the child stands upright
  • Observe in a weight-bearing position with feet together.
  • Bowing may be symmetrical Symmetrical Dermatologic Examination or asymmetrical.
  • Measure intercondylar distance.
  • Waddling gait Gait Manner or style of walking. Neurological Examination is typical.
Pathologic genu varum

Pathologic genu varum in a patient with osteomalacia Osteomalacia Disorder caused by an interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets resulting from disruption of vitamin d; phosphorus; or calcium homeostasis. Osteomalacia and Rickets

Image: “Genu varum” by Latifa Tahiri, et al AL Amyloidosis. License: CC BY 2.0

Diagnosis

Diagnosis is primarily based on clinical examination. It is critical to differentiate between normal physiologic genu varum and a pathologic process.

Diagnostic evaluation

  • Physiologic genu varum:
    • Common normal variant in toddlers
    • Asymptomatic and symmetric
    • Resolves by age 2–3 years 
  • Symptomatic or unilateral genu varum should be referred to an orthopedist.
  • Laboratory evaluation aims to uncover underlying syndrome or disorder:
    • Renal function
    • Vitamin/mineral levels
  • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types densitometry may be appropriate if underlying nutritional/ malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion/metabolic disorder is present.

Imaging

X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:

  • Not indicated in cases of physiologic genu varum
  • Indications for X-rays X-rays X-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography. X-rays:
    • Asymmetrical genu varum 
    • Excessive genu varum
    • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship beyond the age group for physiologic genu varum 
    • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship < 10th percentile height for their age with genu varum
    • History of trauma involving the knee
    • Concern for infection
  • Standing anteroposterior (AP) radiography of the lower extremities:
    • Taken with patellae facing forward 
    • Allows visualization of true and apparent limb lengths and deformities
  • Mechanical axis Axis The second cervical vertebra. Vertebral Column: Anatomy determination:
    • Line drawn from the center of femoral head to center of ankle
    • Line should bisect the knee
    • Genu varum shows medial deviation of the axis Axis The second cervical vertebra. Vertebral Column: Anatomy toward or beyond the joint margin.
  • Deformity Deformity Examination of the Upper Limbs may be femoral, tibial, or both. 
  • AP radiography of wrist to determine bone age Bone Age Short Stature in Children and remaining growth potential
X-ray of a child with genu varum

X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests of a child with genu varum

Image: “ Pseudoachondroplasia in a four-year-old boy, who presented with genu vara and short stature” by Bhattacharya, K., et al AL Amyloidosis. License: CC BY 4.0, cropped by Lecturio.

Management

The majority of cases of genu varum are physiologic and should resolve spontaneously; thus, they require only observation and expectant management.

Nonoperative management

Observation:

1st-line treatment, appropriate if:

  • Patient is within the age range for physiologic genu varum.
  • Spontaneous resolution by age 2–3

Medical management: 

  • Indicated in cases of underlying medical conditions and metabolic disorders:
    • Correct nutritional deficiencies.
    • Optimize bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types formation and mineralization:
      • Vitamin D Vitamin D A vitamin that includes both cholecalciferols and ergocalciferols, which have the common effect of preventing or curing rickets in animals. It can also be viewed as a hormone since it can be formed in skin by action of ultraviolet rays upon the precursors, 7-dehydrocholesterol and ergosterol, and acts on vitamin D receptors to regulate calcium in opposition to parathyroid hormone. Fat-soluble Vitamins and their Deficiencies
      • Calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes
      • Bisphosphonates Bisphosphonates Bisphosphonates are pyrophosphate analogs most well-known for treating osteoporosis by preventing bone loss. Bisphosphonates end in the suffix “-dronate” or “-dronic acid” (e.g., alendronate, risedronate, pamidronate) and bind to hydroxyapatite crystals in bone, inhibiting osteoclast-induced bone resorption. Bisphosphonates
  • Bracing:
    • Not necessary for physiologic genu varum 
    • Not effective for pathologic genu varum
  • Bracing may be used in early treatment of Blount disease.

Surgical management

  • Indicated in severe pathologic genu varum
  • Surgical options:
    • Guided growth with hemiepiphysiodesis or physeal tethering:
      • Indicated for severe varus in children with ≥ 2 years of growth potential 
      • Reversible and minimally invasive 
      • Extraperiosteally placed implants (plates and screws)
      • Implant serves as a tension band for gradual growth changes
    • Distal femoral varus osteotomy:
      •  Indicated in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who are at or near skeletal maturity 
      • Risk of peroneal nerve Peroneal nerve The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot. Popliteal Fossa: Anatomy injury mitigated by peroneal nerve Peroneal nerve The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot. Popliteal Fossa: Anatomy release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology
  • Special surgical considerations in management of Blount disease

Complications

  • Due to failure to recognize pathologic genu varum:
    • Continued progression of unrecognized underlying medical illness
    • Gait Gait Manner or style of walking. Neurological Examination disturbances
    • Premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis
    • Chronic pain Chronic pain Aching sensation that persists for more than a few months. It may or may not be associated with trauma or disease, and may persist after the initial injury has healed. Its localization, character, and timing are more vague than with acute pain. Pain Management
  • Surgical complications Surgical complications Surgical complications are conditions, disorders, or adverse events that occur following surgical procedures. The most common general surgical complications include bleeding, infections, injury to the surrounding organs, venous thromboembolic events, and complications from anesthesia. Surgical Complications:
    • Hardware failure is much less common with newer implants.
    • Physeal injuries due to implants: less common with guided-growth method
    • Overcorrection Overcorrection Volume Depletion and Dehydration or undercorrection
    • Neurovascular injury ( peroneal nerve Peroneal nerve The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot. Popliteal Fossa: Anatomy injury with osteotomy) 
    • Infection
  • Most cases of physiologic genu varum resolve spontaneously by age 2–3 years.
  • Results of cases of pathologic genu varum using guided-growth techniques with close follow-up are generally positive.

Clinical Relevance

  • Rickets Rickets Disorders caused by interruption of bone mineralization manifesting as osteomalacia in adults and characteristic deformities in infancy and childhood due to disturbances in normal bone formation. The mineralization process may be interrupted by disruption of vitamin d; phosphorus; or calcium homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances. Osteomalacia and Rickets and osteomalacia Osteomalacia Disorder caused by an interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets resulting from disruption of vitamin d; phosphorus; or calcium homeostasis. Osteomalacia and Rickets: disorders of decreased bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types mineralization. Rickets Rickets Disorders caused by interruption of bone mineralization manifesting as osteomalacia in adults and characteristic deformities in infancy and childhood due to disturbances in normal bone formation. The mineralization process may be interrupted by disruption of vitamin d; phosphorus; or calcium homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances. Osteomalacia and Rickets affects the cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage: Histology of the epiphyseal growth plates Growth Plates The area between the epiphysis and the diaphysis within which bone growth occurs. Osteosarcoma in children, while osteomalacia Osteomalacia Disorder caused by an interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets resulting from disruption of vitamin d; phosphorus; or calcium homeostasis. Osteomalacia and Rickets affects the sites of bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types turnover in children and adults. Although most cases of rickets Rickets Disorders caused by interruption of bone mineralization manifesting as osteomalacia in adults and characteristic deformities in infancy and childhood due to disturbances in normal bone formation. The mineralization process may be interrupted by disruption of vitamin d; phosphorus; or calcium homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances. Osteomalacia and Rickets and osteomalacia Osteomalacia Disorder caused by an interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets resulting from disruption of vitamin d; phosphorus; or calcium homeostasis. Osteomalacia and Rickets are due to vitamin D deficiency Vitamin D Deficiency A nutritional condition produced by a deficiency of vitamin D in the diet, insufficient production of vitamin D in the skin, inadequate absorption of vitamin D from the diet, or abnormal conversion of vitamin D to its bioactive metabolites. It is manifested clinically as rickets in children and osteomalacia in adults. Fat-soluble Vitamins and their Deficiencies, other genetic and nutritional disorders, as well as medications, can cause these disorders.
  • Vitamin D deficiency Vitamin D Deficiency A nutritional condition produced by a deficiency of vitamin D in the diet, insufficient production of vitamin D in the skin, inadequate absorption of vitamin D from the diet, or abnormal conversion of vitamin D to its bioactive metabolites. It is manifested clinically as rickets in children and osteomalacia in adults. Fat-soluble Vitamins and their Deficiencies: state of deficiency of the forms of vitamin D Vitamin D A vitamin that includes both cholecalciferols and ergocalciferols, which have the common effect of preventing or curing rickets in animals. It can also be viewed as a hormone since it can be formed in skin by action of ultraviolet rays upon the precursors, 7-dehydrocholesterol and ergosterol, and acts on vitamin D receptors to regulate calcium in opposition to parathyroid hormone. Fat-soluble Vitamins and their Deficiencies, which alters the homeostasis Homeostasis The processes whereby the internal environment of an organism tends to remain balanced and stable. Cell Injury and Death of calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes due to deficient absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption in the diet and reabsorption in the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy.

References

  1. Browner, B., Jupiter, J., Krettek, C., Anderson, P. (2020). Skeletal Trauma: Basic Science, Management, and Reconstruction. Philadelphia: Elsevier.
  2. Kliegman, R., et al. (2020). Nelson Textbook of Pediatrics. Philadelphia: Elsevier.
  3. Zitelli, B., McIntire, S., Nowalk, A. (2018). Zitelli and Davis’ Atlas of Pediatric Physical Diagnosis. Philadelphia: Elsevier.
  4. Murthy, D., & De Leucio, A. (2021). Blount disease. StatPearls. Retrieved June 24, 2021, from http://www.ncbi.nlm.nih.gov/books/NBK560923/

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