Knee Development Issues in Children of Different Ethnic Groups

A lot of children visit doctors because of their guardians worry about the TF angle of their children. Knowing the average range of the knee angle is most importance to avoid needless radiation and therapeutic procedure (orthotics or bracing). A reassurance on the part of the treating medical doctor helps alleviate the stress of the parents worried about the ‘‘bending of the knees’’ of their children.

The TF angles at various age groups differ and ethnic variations are likely to be present. The doctor should, know these variations in their local population to create applicable treatment options, there are many studies regarding normal development of the knee angle in Nigerians, Koreans, and Turkish children.

Several methods have been used to measure the TF angles in children. Radiographic methods which are commonly used, are time-consuming and have ethnical problem related to needless radiation exposure in children. Further, a malrotation of the limb, if not taken care of, might lead to significant errors in the measurement of the TFA. Clinical methods of measuring the TF angles are acceptable and reproducible, with the advantage of being cheap and radiation-free. We used fixed bony points to calculate the TFA and the ICD and IMD using goniometer. Palpation of fixed bony landmarks is practical and easy. Also, the measurements are less likely to be erroneous, even in obese children and in children with marked femoral bowing which might preclude the exact location of the femur. The development of the TFA could be divided into three phases:first phase, during which knee alignment changes from an infantile physiologic varus to maximum valgus; second phase, when valgus knee alignment decreases in amount; and third phase, during which knee alignment remains stationary.

Anyway, the age ranges at which these phases come in children has been found to be varied in children with different ethnic groups In our present study, we found that none of the subjects had a negative TFA in the 2 years age group, the mean TFA was positive in Saudi children, even at the age of 2 years. This was the opposite to the findings of the largest study by Cheng et al. In the Chinese population, which stated a mean varus TFA at the age of 2 years. the authors noted a rapid decrease in the mean IMD in the Chinese children, reaching 0 cm at the age of 8 years, with a normal range of ±3 cm. Conversely, we observed both the ICD and IMD were variable with age.

We also found that the maximum mean TFA (9. 70) with the age group between13 years, while in boys, the maximum mean TFA (11. 75) was seen in the same age group. Thereafter, the mean TFA stabilized to lie between 5 and 9 in most of the children. Saudi girls showed the maximum valgus of 18° recorded in normal girls at age 5 and 8 years, and normal boy at age of 8 year.

Our results were contrary to those of Oginni et al. , who estimated the knee angles of 2, 036 normal Nigerian kids up to an age of 12 years. In their study, they noted the huge portion of the knees to be bowed (varus) in the first 6 months. At 21–23 months of age, the distribution of angles became strongly bimodal: about half being varus and half being valgus (knock-kneed). After this, the knee angle was noted to be valgus in huge portion of the youngsters. They found that the change from varus to valgus in infants could be sudden (a few weeks), although the changeover of the whole population appeared gradual. The authors also found that varus knee alignment was uncommon after 2 years in Nigerian children and large knee angles between 2 and 5 years suggested rickets. However, in their study, the children became maximally and uniformly knock-kneed (-7. 1±1. 4) between 3 and 3. 5 years, with little change thereafter. This is contrary to our findings in Saudi children, in whom the maximum valgus has been noted to occur at an age of 5 and 8 years. our results had little increase in the mean valgus was 11.

Our results had little increase in the mean valgus was 11, 17 at the age of 13 compared to the study that has been done in India where the maximum valgus 9, 8 at the age of 6. The Indian study concluded that Indian children exhibiting maximum valgus 11 and any child measured higher than that should be considered abnormal. We should consider that different ethnic group has different patterns when it comes to knee development.