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Luau Limbo and the Age for Rigid Nailing of Pediatric Femoral Fractures: How Low Can You Go?

2014; Wolters Kluwer; Volume: 96; Issue: 13 Linguagem: Inglês

10.2106/jbjs.n.00298

1535-1386

Mark C. Lee,

Hip disorders and treatments

Commentary Pediatric femoral fractures are typically treated with age-dependent protocols that consider both the growth and remodeling potential of the femur and patient characteristics such as weight and socioeconomic environment of the child. Although it is generally agreed that children five years of age or younger can be adequately managed with a spica cast for length-stable femoral fractures, the range of treatment options for patients between the ages of five years to skeletal maturity span the gamut of flexible nailing, submuscular plating, external fixation, and trochanteric entry rigid intramedullary nailing. Piriformis entry rigid nails are generally shunned in pediatric practice because of a clear association with osteonecrosis1. Trochanteric entry rigid intramedullary nailing is advantageous in treating pediatric femoral shaft fractures in several respects. First, when compared with flexible nails, proximal and distal interlocking allows unmatched length and rotational control of complex injuries. Second, this load-sharing device does not fear the obese child2. Finally, the average orthopaedic surgeon is well trained in this technique and can offer reproducible results. For a femoral fracture in a child nearing skeletal maturity, the choice of rigid intramedullary nail fixation generates no particular debate. However, great concern exists for children with the approximate ages of five to fourteen years. Use of a trochanteric entry device in a child with substantial growth potential can theoretically lead to subsequent growth disturbance of the proximal femur and/or osteonecrosis of the femoral head3,4. For every orthopaedist involved in the treatment of pediatric femoral fractures, the questions that arise with the use of this implant are whether the technique is generally safe and what the youngest patient age is at which a trochanteric entry rigid nail can be used. The article by Crosby et al. attempts to address these two questions by presenting a single-institution, retrospective chart and radiograph review, combined with data from a functional survey, of an unprecedented collection of 241 pediatric patients who had undergone trochanteric entry rigid intramedullary nailing for femoral shaft fractures from 1987 to 2009. The average follow-up was sixteen months, with ninety-three patients having a minimum two-year follow-up. The overall complication rate was 9.8%. Thirty-nine patients with a mean time from surgery of eighty-three months were available for administration of a Nonarthritic Hip Score and survey questions. Of this subset, 100% were satisfied with their treatment, with only one patient reporting severe pain at night. The authors are to be congratulated for presenting a cogent argument on the relative safety of trochanteric entry nailing and its ability to successfully treat femoral fractures. No cases of osteonecrosis were encountered in a group whose follow-up ranged from three to seventy-nine months. Complication rates were notably low, with only one case of deep infection (<1%) and six cases of delayed union or malunion (2.4%) among the 246 fractures. It is arguable whether asymptomatic Brooker class-I heterotopic ossification can be considered a complication and, if such patients were deleted from the complication numerator, the final complication rate would be 5.3%. Importantly, the subgroup of patients with more than two years of follow-up is analyzed separately and demonstrates similar complication rates to the total cohort, suggesting that the cohort data are able to be generalized to patients followed for the long term. The information is beneficial to both the surgeon’s and parents’ decision to use this technique for an injured child. Unfortunately, this article is less effective at persuading the reader that trochanteric entry nailing does not yield a growth disturbance of the proximal femur, manifested as proximal femoral valgus and/or a clinically important limb-length discrepancy at maturity. First, more than two-thirds of the study cohort were followed for less than two years, an inadequate length of time to identify slowly evolving growth differences in the proximal femur. Second, switching from full-length radiographs to block testing to determine limb-length discrepancy for patients included after 2000 impaired direct comparisons with the earlier group and likely introduced inaccuracies in measuring the femoral contribution of a limb-length difference for the latter group5. Third, almost half of the study cohort underwent intramedullary nail removal, confusing the issue of whether the limb-length differences in some children were the result of the original or subsequent surgery. Finally and most importantly, no patient enrolled had a graded radiographic determinant of overall maturity, such as a bone age or Oxford score. The failure to stratify patients according to skeletal maturity potentially dilutes the true incidence of adverse growth phenomena. For example, if only a handful of patients in the cohort were truly skeletally immature at the time of nailing and experienced growth arrest, their particular complication rate is minimized when the great majority of the cohort is skeletally mature and is included in the denominator. The current data ultimately serve to provide excellent descriptive statistics on specific complications following trochanteric entry rigid nailing in a pediatric population. A clearer understanding of the potential growth disturbance introduced by a trochanteric entry nail in a skeletally immature patient will ideally leverage a prospective study that captures bone ages and standardized full-length radiographs for limb-length difference calculations. For the time being, a safe age for trochanteric entry rigid nailing to minimize proximal femoral growth disturbance remains elusive. And so, the luau limbo continues.