Fig. 2.

a This 3-year-old boy presented with a 2.9 cm limb length inequality and right knee pain. The cruciate ligament laxity, hypoplastic lateral femoral condyle, shallow sulcus, and retroversion together contribute to maltracking of the patella. b Commencing with guided growth of the medial right femur at age 3 years, this patient has undergone a series of outpatient surgeries with minimal scars and no functional limitations. Serial guided growth of the right distal medial femur has restored/maintained a neutral mechanical axis. Sequential tethering/untethering of the normal left femur has mitigated the limb length discrepancy. He will now undergo reinsertion of the metaphyseal screw on the right and addition of a lateral plate on the left. c In addition to the frontal plane angular adjustment, there are transverse plane benefits as well, including a deeper patella femoral sulcus and correction of femoral retroversion