Columbus, OH — May 2018
In the past, limb lengthening and femoral deformity correction meant a long, painful, very visible process — an external fixator with manual adjusters, a knee that was difficult to bend, high infection risk and more. Now, orthopedic surgeons from multiple institutions have shown that both procedures can effectively be done at the same time with just an internal nail system.
The device that makes this dual internal treatment possible is the PRECICE® nail (NuVasive). Traditionally used just for limb lengthening over a period of a few months, a recent study in the Journal of the American Academy of Orthopaedic Surgeons shows how this internal magnetic nail system can be used for deformity correction as well.
“The vast majority of patients we see don’t just show up with a straight leg that’s short. They often have additional deformities, such as bowing, knock knees or rotational problems,” says Christopher Iobst, MD, director of the Center for Limb Lengthening and Reconstruction at Nationwide Children’s Hospital and a member of the hospital’s Department of Orthopaedics. “We wanted to know if we could use this nail for lengthening on the inside and combine it in a technique to straighten the limb for patients who also need a correction.”
The technique the collaborators adopted involves temporary external fixation during the surgery. After the deformation is acutely addressed with the fixator, the PRECICE nail rod is implanted to enable the limb lengthening, placing blocking screws in carefully selected locations to both secure the nail and maintain the deformity correction. Dr. Iobst, who is first author on the paper describing the technique, conducted the research during his time as director of orthopedic research at Nemours Children’s Hospital, together with colleagues from two other hospitals.
The surgeons retrospectively analyzed the innovative technique using the medical records of 27 patients who needed limb lengthening and deformity correction at the same time. The patients ranged in age from 13 to 57 years and had mildly complex deformities (an average score of 4.6 on the Limb Lengthening and Reconstruction Society AIM scale, which measures procedure complexity from 0 to 28). In addition to limb length discrepancies, patients had various secondary deformities including valgus, varus, external rotation and apex anterior deformities.
Average lengthening was 30 mm, and ASAMI-Paley scores (Association for the Study and Application of Methods of Ilizarov) were “excellent” for 26 patients and “good” for the remaining patient. After completion of the therapy, average limb-length discrepancy was 0.8 mm, and 93 percent of patients were within 3 mm; two patients had residual differences of 6 mm. A discrepancy of less than 10 mm is considered within normal range.
Angle corrections averaged 7 degrees (with a maximum of 15 degrees). All patients retained knee extension within 5 degrees of full extension, and average time to full weight bearing was 89 days. No patients had infections, mechanical failures or bone fractures, although four patients had complications requiring further care or procedures.
“This proves that multiplanar deformity can be acutely and safely corrected from the inside with gradual lengthening at the same time,” says Dr. Iobst. “This approach was never documented before. It highlights a really elegant way to handle these problems without the use of an external device and daily manual adjustments to straighten and lengthen the limb. For patients, the difference is revolutionary.”
Although the technique met with great success among the studied patient population, it is not appropriate for all types of deformities and is quite challenging technically. Dr. Iobst recommends that physicians without considerable experience with the PRECICE nail implants and deformity correction should not attempt simultaneous internal correction and lengthening. However, Dr. Iobst welcomes other physicians to the Center for Limb Lengthening and Reconstruction at Nationwide Children’s to observe and learn the technique.
“This approach absolutely should become the standard,” says Dr. Iobst. “I don’t know anybody who would want to go back to the old way. The simultaneous internal method is so much more comfortable, and patients have a much higher level of satisfaction — it’s amazingly better.”
As one of several studies in progress, Dr. Iobst is developing patient-reported outcome survey tools for patients undergoing limb deformity corrections to help facilitate standardized, comparable outcomes research in the field.
Iobst CA, Rozbruch SR, Nelson S, Fragomen A. Simultaneous Acute Femoral Deformity Correction and Gradual Limb Lengthening Using a Retrograde Femoral Nail: Technique and Clinical Results. Journal of the American Academy of Orthopaedic Surgeons. 2018 Apr 1; 26(7):241-250.