Summary External Tibial Torsion is a rare developmental condition in young children caused by abnormal external rotation of the tibia leading to an out-toeing gait. Diagnosis is made clinically with a thigh-foot angle measuring greater than 20 degrees of external rotation. Treatment is generally nonoperative with rehab and activity modications for the majority of patients. Surgical management is indicated for children older than 8 years of age with external tibial torsion greater than three standard deviations above the mean ( >40 degrees external). Epidemiology Anatomic location may be bilateral but if unilateral most commonly involves the right lower extremity. Etiology Associated Conditions miserable malalignment syndrome a condition defined as external tibial torsion with femoral anteversion Osgood-Schlatter disease osteochondritis dessicans early degenerative joint disease an association between external tibial torsion and early degenerative joint disease has been found neuromuscular conditions may be found with neuromuscular conditions such as myelodysplasia and polio Anatomy Normal development tibia externally rotates on average 15 degrees during early childhood femoral anteversion decreases on average 25 degrees during this time as well Presentation Symptoms anterior knee pain caused by patellofemoral malalignment Physical Exam thigh-foot axis measurement best way to evaluate tibial torsion average during infancy is 5 degrees internal rotation, that slowly derotates average at 8 years of age is 10 degrees external, ranging from -5 to +30 degrees technique lie patient prone with knee flexed to 90 degrees thigh-foot-axis is the angle subtended by the thigh and the longitudinal axis of the foot transmalleolar axis measurement another way to evaluate tibial torsion average at infancy is 4-5 degrees internal rotation average at adulthood is 23 degrees external (range 0-40 degrees external) technique lie patient supine an imaginary line from medial malleolus to lateral malleolus and another imaginary line from medial to lateral femoral condyle is made the axis is the angle made at the intersection of these two lines this helps to determine the direction and extent of tibial torsion present Imaging Usually none required. Treatment Nonoperative rest, rehab, and activity modifications indications first line of treatment Operative supramalleolar derotational osteotomy or proximal tibial derotational osteotomy indications surgery is reserved for children older than 8 years of age with external tibial torsion greater than three standard deviations above the mean ( >40 degrees external). more likely to require surgery than internal tibial torsion Techniques Supramalleolar rotational osteotomy technique osteotomy supramalleolar rotational osteotomy is most commonly performed fibula is obliquely osteotomized if the deformity is severe proximal tibial osteotomies are avoided secondary to higher risk factors associated with this procedure plate fixation cross pin fixation or plate fixation intramedullary fixation IM fixation with rotational osteotomy is reserved for skeletally mature adolescents Prognosis Since the leg externally rotates with physical growth, this deformity usually worsens during late childhood and early adolescence.