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    Comparing Methods for Correcting LLD in Pediatric Patients

    In the right patients, either percutaneous physeal epiphysiodesis or 8-plate epiphysiodesis can effectively treat limb length discrepancy. But according to a recent study, in some cases, percutaneous treatment is preferred.

    Authors

    David P. Taormina, MD, and Alice Chu, MD

    Article

    Bayhan IA, Karatas AF, Rogers KJ, Bowen JR, Thacker MM. Comparing percutaneous physeal epiphysiodesis and eight-plate epiphysiodesis for the treatment of limb length discrepancy. J Ped Ortho. 2017;37(5), 323-327.

    Summary

    Orthopaedic surgeons have 2 options for epiphysiodesis when treating limb length discrepancies (LLD): permanent percutaneous epiphysiodesis or temporary use of an 8-plate construct. Few studies have compared outcomes of these methods.

    Using long-leg standing radiographs and scanograms as their outcome measures, Bayhan et al have now added to the scant literature on this topic with their comparison of the 2 options.

    The paper is a retrospective evaluation of data collected on 72 patients who underwent surgery of the distal femur and/or proximal tibia between 2004 and 2012 to treat LLD of 2.5 cm to 5 cm (n=24 in the 8-plate group; n=48 in the percutaneous epiphysiodesis group).

    Patients were excluded if they had undergone additional surgery; if they had angular deformities; or if they had been diagnosed with skeletal dysplasia, Blount’s disease, or malignancy.

    The authors measured:

    • Rate of correction (mm/month)
    • Percentage of correction, defined as (initial discrepancy – final discrepancy)/initial discrepancy
    • Differences in complications and complication rates

    Standing full-length lower extremity x-rays (or scanograms) were performed of all patients and measurements were made using the PACS system. Mosely’s straight-line method was used to determine the timing of epiphysiodesis. The surgical technique for permanent percutaneous epiphysiodesis was based on the technique described by Bowen and Johnson, using a drill instead of an osteotome. All 8-plate patients received a single plate on each side of the physis.

    Among the 24 patients in the 8-plate group:

    • 17 (71%) had undergone epiphysiodesis of the distal femur only
    • 3 (12.5%) had undergone epiphysiodesis of the proximal tibia only
    • 4 (16.5%) had undergone epiphysiodesis of the the distal femur and proximal tibia

    Among the 48 patients in the percutaneous epiphysiodesis group:

    • 29 (60%) had undergone epiphysiodesis of the distal femur only
    • 8 (17%) had undergone epiphysiodesis of the proximal tibia only
    • 11 (23%) had undergone epiphysiodesis of the distal femur and proximal tibia

    Mean age at surgery was 12 years old for the 8-plate group and 13 years old for the percutaneous epiphysiodesis group.

    At final follow-up, both groups had been corrected from a preoperative LLD of 3.0 cm and 2.9 cm to a mean below 2.0 cm, with the percentage of improvement significantly greater in the percutaneous epiphysiodesis group than in the 8-plate group (58% vs 41%; P=0.03).

    The rate of femoral correction and tibial correction did not differ between groups:

    • For the distal femur, the rate of correction was 0.37 mm/month in the 8-plate group and 0.41 mm/month in the percutaneous epiphysiodesis group.
    • For the proximal tibia, the rates of correction were 0.4 mm/month in the 8-plate group and 0.43 mm/month in the percutaneous epiphysiodesis group.

    No aberrant outcomes were reported among the percutaneous epiphysiodesis group. In the 8-plate group, 1 patient developed superficial stitch abscess.

    In addition, 14 patients underwent removal of hardware after maturity, 7 of whom had tender and palpable prominent hardware, and 2 of the 8-plate patients had hardware breakage.

    One of these patients, as well as 4 other patients who were identified as having slow rates of LLD correction (mean of 6 mm at approximately 18 months) had supplemental treatment in the form of percutaneous epiphysiodesis for their adjacent physis, which had been untreated at the time of index surgery (2 patients with supplemental distal femoral percutaneous epiphysiodesis and 3 patients with supplemental proximal tibial percutaneous epiphysiodesis).

    Clinical Relevance

    Varying outcomes have been published for patients undergoing LLD correction with the use of 8-plates applied peripherally to the medial and lateral distal femoral and proximal tibial physes. The reversibility of 8-plate application has led to its use in the treatment of limb-length discrepancy.

    There remains, however, a significant body of literature supporting the safe and reliable use of permanent percutaneous epiphysiodesis to treat LLD correction. The potential and theoretical challenges of percutaneous epiphysiodesis tend to be secondary to poor surgical timing, miscalculation of skeletal age, or measurement mistakes on scanograms.

    In this study, no complications occurred among 48 patients who had undergone percutaneous epiphysiodesis due to the use of the Mosely straight-line graph technique for determining timing of surgery.

    The conclusion of this study is that in the appropriate patients, either technique can be used to effectively correct LLD.

    The study suggests, however, that percutaneous epiphysiodesis achieves a greater rate of improvement with a decreased rate of complications, including the need for additional surgery and/or conversion to supplemental treatment using an alternative epiphysiodeseal method.

    Thus, the authors caution that patients undergoing 8-plate epiphysiodesis should prudently be followed up at regular intervals to closely monitor the rate of correction and assess for potential issues requiring additional procedures in a timely manner.

    Author Information

    David P. Taormina, MD is an orthopaedic surgery resident at NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York. Alice Chu, MD is an Attending Pediatric Orthopaedic Surgeon and Assistant Professor in the Department of Orthopaedic Surgery at NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York where she specializes in hand and upper extremity surgery.