Tibial torsion is inward twisting of the tibia (shinbone) and is the most common cause of intoeing. It is usually seen at age 2 years. Males and females are affected equally, and about two thirds of patients are affected bilaterally. 
Normally, lateral rotation of the tibia increases from approximately 5º at birth to approximately 15º at maturity. Whereas medial torsion improves with time, lateral torsion often worsens because the natural progression is toward increasing external torsion. The ability to compensate for tibial torsion depends on the amount of inversion and eversion present in the foot and on the amount of rotation possible at the hip. Internal torsion causes the foot to adduct, and the patient tries to compensate by everting the foot, externally rotating at the hip, or both. Similarly, persons with external tibial torsion invert at the foot and internally rotate at the hip. [2, 3, 4, 5, 6, 7, 8, 9]
The natural history of femoral torsion is to resolve by the time the patient is aged 8-9 years. Beyond this age, all remodeling will have occurred, and any further correction is due to a conscious modification of posture.
Normal femoral anteversion is 40º in the newborn and decreases to 10º by the age of 8 years. The acetabulum is angled forward 15º. Femoral anteversion does not increase the risk of arthritis of the hip. Spontaneous improvement in the anatomic position can occur up to the age of 8 years, and further correction can be achieved by improving the gait through conscious effort until adolescence.
In a study by Mullaji et al to determine tibial torsion norms, individuals in India were found to have less tibial torsion than Caucasians but about the same amount as the Japanese population.  The differences in normal tibial torsion values are expected to be caused by the different lifestyles and postures of the different populations, such as cross-legged sitting positions. [10, 11, 12, 13]
Drexler et al conducted a study to evaluate the clinical and radiographic outcomes of 12 patients (15 knees) undergoing tibial derotation osteotomy and tibial tuberosity transfer for recurrent patella subluxation associated with excessive external tibial torsion.  Clinical evaluation was carried out using preoperative and postoperative Knee Society Score, Kujala Patellofemoral score, the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire, the short form-12, and a visual analogue score pain scale.
Significant improvement was achieved on all measures.  Two patients had a nonunion of the tibial osteotomy site, one patient required bone grafting, and another patient required revision to total knee arthroplasty. The investigators concluded that for patients with recurrent patella subluxation secondary to excessive external tibial torsion, satisfactory outcomes in terms of pain relief and improved function can be achieved through tibial derotation osteotomy and tibial tuberosity transfer.
In a study of surgical treatment of 44 children with torsional malalignment of the tibia, Erschbamer et al performed 71 percutaneous derotational osteotomies of the distal tibia. followed by application of an external fixator.  On postoperative radiographs, accurate tibial derotation and pin placement were noted in all patients. In nine patients, superficial pin-tract infections developed but resolved with administration of antibiotics; in two. fractures developed after the external fixator was removed but healed in a plaster cast. The investigators found this approach to be safe, effective, and well tolerated.