A Randomized Controlled Trial of Leg Length Discrepancy Techniques

Drill and screw epiphysiodesis are the two most common techniques for surgical correction of
predicted limb length discrepancies 2-5cm. Both procedures require minimal incisions, less
than 1cm, (Canale & Christian, 1990; Metaizeau et al., 1998). Previous studies have
demonstrated that both drill and screw epiphysiodesis result in improved outcomes compared to
open techniques (Alzahrani, Behairy, Alhossan, Arab, & Alammari, 2003; Canale & Christian,
1990). Moreover, alternative approaches such as medial and lateral 8 plates may not
sufficiently tether growth, or cause peripheral but not central growth arrest (Stewart et
al., 2013). We selected drill vs. screw epiphysiodesis as the two treatment groups as they
are both minimally invasive, relatively effective, in common usage, and are thought to differ
in costs and other characteristics.

Although outcomes of drill and screw epiphysiodesis exist{{10 Campens,C. 2010; 11 Ghanem,I.
2011}} , the assessments are retrospective non-randomized series, which may be at risk for
selection bias, and may not adequately capture all of the outcomes of interest, depending on
what data is routinely collected and documented in the medical chart. To our knowledge, no
prospective randomized comparison of epiphysiodesis techniques and clinical outcomes has been
published accurately assessing how effective each technique is in disabling growth at the
physis, or taking into account patient-centered outcomes or cost. Operative measures such as
the surgical time and radiation exposure from intra-operative fluoroscopy have not previously
been compared. Patient-centered outcomes such as level of pain, activity, and function by
measures such PROMIS and Ped-FABS, have not been previously assessed in this population. The
proposed research study aims to fill this gap.

This study was designed as a multicenter randomized trial to answer an important clinical
question and to do so with a clearly defined objective and validated outcomes. This trial can
be executed on a relatively small budget with simple outcome measures, and recruitment of a
moderate number of patients at each of a few centers well equipped for research. By involving
multiple surgeons and patients from various geographies, we improve the generalizability of
this study. Our institution and collaborating institutions have been successful in completing
randomized clinical trials in the past. This study will answer a clinical question that is
important and current, providing orthopedic surgeons with an evidence-based identification of
the ideal technique for treating predicted limb length discrepancies 2-7cm.

This study will also be the first to accurately measure mean growth following both
epiphysiodesis techniques, through implantation of tantalum beads in consenting participants.
These beads will provide stationary landmarks by which growth can be measured directly, and
not inferred. Previous methods of judging epiphysiodesis success have primarily relied on
assessing efficacy by estimating growth inhibition through calculation. Tantalum beads have
been successfully used in adults and children (Lauge-Pedersen,H. 2006), and although it
requires implantation of small radio-opaque beads, it is considered the gold standard when
making detailed radiographic measures, and the optimal technique for physeal growth
measurements.(Lauge-Pedersen,H. 2006)(Haugan,K. 2012). Over 300 000 beads have been inserted
in vivo without significant complications.

Inclusion Criteria:

- Open growth plates

- Skeletally immature requiring isolated complete epiphysiodesis of the distal femur
and/or proximal tibia

- At least one year of predicted growth remaining

- Less than 18 years of age

- Predicted limb length discrepancy 2-7 cm

Exclusion Criteria:

- Patients undergoing additional orthopedic procedures at time of epiphysiodesis

- Metabolic bone disease or "sick physis" syndrome, that may cause bone to grow in an
unpredictable manner.

- Pregnancy