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Introduction
  • A longitudinal deficiency of the tibia with varying degrees of tibial absence
    • previously known as tibial hemimelia
  • Genetics
    • autosomal dominant inheritance pattern
      • obtain genetic counseling
  • Associated conditions
    • musculoskeletal conditions present in 75% of patients   
      • ectrodactyly
      • preaxial polydactyly
      • ulnar aplasia
Classification
  • Jones classification: types I- IV

1a: No proximal tibia visible on radiograph.  Extensor mech absent. Hypoplastic distal femoral epiphysis

1b- Proximal tibia eventually ossifies and extensor mechanism will function.  Distal femoral epiphysis appears normal

2- Proximal tibia present at birth but short tibia

3- diaphyseal and distal tibia present but proximal tibia absent

4- short tibia, fibula migrated proximal, diastasis of distal tib-fib joint

  • Alternate system is Kalamachi and Dawe  (types 1-3)
Presentation
  • Physical exam
    • deformity
      • shortening of the affected extremity
      • anterolateral bowing of the tibia
      • prominent fibular head
    • ROM & stability
      • the knee is usually flexed with an associated knee flexion contracture 
        • it is important to evaluate for active knee extension
      • check stability of the knee joint in all planes
        • treatment is based primarily on the stability of the knee joint
    • foot deformity
      • there is often a rigid equinovarus and supination deformity of the foot
      • sole of foot faces perineum
Imaging
  • Radiographs
    • recommended
      • AP and lateral tibia/fibula 
    • findings
      • show deficiency of the tibia  
      • early radiographs may show small and minimally ossified distal femoral epiphysis
Treatment
  • Operative
    • knee disarticulation followed by prosthestic fitting
      • indications
        • complete  absence of the tibia
        • no active knee extension present (most cases)
    • tibiofibular synostosis with modified Syme amputation
      • indications
        • proximal tibia present with intact extensor mechanism and minimal flexion contracture 
    • Syme/Boyd amputation
      • indications
        • ankle diastasis
    • Brown Procedure (centralization of fibula under femur)
      • no longer recommended due to high failure rate
 

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Questions (1)

(OBQ06.90) A 13-month-old boy has shortening and deformity of the right leg. A clinical photograph and radiograph are provided in Figures A and B. Which of the following findings most predictive of a good outcome with a Syme amputation? Review Topic

QID:201
FIGURES:
1

35 degree flexion contracture

1%

(15/1575)

2

Absence of tibiofibular synostosis

10%

(155/1575)

3

Bilateral involvement

0%

(6/1575)

4

Full functional quadriceps strength

88%

(1380/1575)

5

Family history of tibial hemimelia

1%

(10/1575)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The clinical scenario and images demonstrate tibial hemimelia. An amputation below the knee has greater likelihood of success if there is a functional quadriceps and no flexion contracture of the knee. Otherwise, a knee disarticulation may be necessary.

Kalamchi et al review 24 cases of tibial hemimelia to establish a classification scheme. Type I is total absence of the tibia. Type II is distal absence of the tibia. Type III is distal deficiency with tibiofibular diastasis. Assessment of the quadriceps function and degree of flexion contracture is crucial to following the appropriate treatment option.


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