Guided growth for pathological physes: radiographic improvement during realignment.

BACKGROUND:
Children with rickets are prone to having deformities of the lower extremities that are bilateral and often symmetrical. Although initially attributed to pathological or "sick" physes, the deformities are eventually seen in the metaphyses and diaphyses of the long bones; if left untreated, they may result in bone pain and stress fractures. The orthopaedists' role in managing these children is to correct and maintain alignment. Alternatively, we have exploited the use of hemiepiphysiodesis or guided growth, using staples or, more recently, the 8-plate (Orthofix, Verona, Italy). While gradually normalizing the mechanical axis, we have noted improvement in the appearance and width of all of the ipsilateral physes, not only at the knee but at the hip and ankle as well. This report summarizes our observations of the effects on the pathological physes in a group of patients with rickets who were preferentially treated with guided growth, often starting at a young age.

METHOD:
This retrospective review approved by an institutional review board included 14 children with rickets, including 10 treated with staples and 4 with 8-plates, who collectively underwent a total of 68 hemiepiphysiodeses (guided growth) and 35 osteotomies. Each was under appropriate medical management during the entire course of treatment, before and after surgery. We measured the mechanical axis deviation and anatomic angles of the femur and proximal tibia, noting the width and appearance of their physes at the hips, knees, and ankles preoperatively and upon correction of the axis.

RESULTS:
Of the 10 stapled patients, we noted 24 (45%) of 53 migrations and 41% rebound deformity. Four patients with 15 deformities that corrected with 8-plates experienced no hardware migration; for them, it is too early to comment on rebound deformity. While gradually correcting the mechanical axis, we have noted improvement in the appearance and width, not only of the pan-genu physes but also of remote physes at the hip and ankle. We suspect that the improved quality of the physes reflects not only the normalization of the mechanical axis but also the corresponding resolution of the waddling (varus) or circumduction (valgus) gait pattern.

CONCLUSION:
We recommend early intervention, via guided growth, to restore and preserve a neutral axis so that the child can enjoy a normal lifestyle while maximizing the growth potential of his or her physes, not only of the knees but the hips and ankles as well. We believe that by correcting and maintaining alignment, secondary bony deformities may be ameliorated and osteotomies for angular correction deferred if not avoided altogether.

LEVEL OF EVIDENCE:
IV (retrospective clinical series).