IN BRIEF

Finding the Best Treatment for Stable but Severe Slipped Capital Femoral Epiphysis

September 28, 2020

A novel comparison of the modified Dunn procedure for children with stable vs unstable SCFE has identified a new target to improve surgical outcomes.

The modified Dunn procedure uses a surgical hip dislocation approach to realign the hip joint in adolescents with slipped capital femoral epiphysis (SCFE) — a condition in which the ball of the hip joint separates from the main thigh bone. The condition can occur gradually (called chronic, stable SCFE) or suddenly, from an injury or fall (called acute, unstable SCFE). When the condition prevents any weight-bearing, it is considered “unstable.”

In mild or moderate stable cases, percutaneous screw fixation can help reconnect the bones properly and prevent further slippage. In more severe cases of stable SCFE or in unstable SCFE, however, that approach cannot correct the slip without lasting deformities, so the modified Dunn procedure may be used to manually realign and connect the bones.

Corrective realignment surgery was controversial for many years due to the high rate of avascular necrosis produced from surgery itself, which many studies found to be as high as 60%. Surgeons at Nationwide Children’s Hospital have managed to achieve far lower than average postsurgical avascular necrosis rates for unstable SCFE cases, however (~6%, which they published in 2018 in the Journal of Pediatric Orthopedics). In an attempt to offer better future mobility outcomes for other patients as well, they then extended the use of the modified Dunn procedure to severe cases of stable, chronic SCFE.

In the first known comparison of outcomes for patients with stable vs unstable SCFE undergoing the modified Dunn procedure, surgeons at Nationwide Children’s found that the procedure can effectively treat both forms of SCFE. Unfortunately, those with stable SCFE had a higher postsurgical complication rate, primarily due to the co-occurrence of avascular necrosis and postoperative instability. In patients without postoperative instability of the hip, however, avascular necrosis risk was similar across the groups.

“The modified Dunn procedure is very effective and relatively safe in acute unstable slips, but it needs to be used more cautiously in stable chronic cases—especially those with a more severe slip,” says Kevin E. Klingele, MD, chief of Orthopaedic Surgery at Nationwide Children’s and senior author on the latest study, also published in the Journal of Pediatric Orthopedics. “Avoiding postoperative instability may be the key to lowering complication or avascular necrosis rates in this procedure to a more acceptable level for severe, stable slip patients.”

Since conducting the research, Dr. Klingele and the team’s other orthopedic surgeons have attempted to eliminate postoperative instability by combining relative femoral neck lengthening procedure, longer postoperative leg bracing and motion restrictions, and capsulorrhaphy techniques (suturing to tighten the hip joint). They have had no postoperative instability in patients with chronic, stable SCFE since.

If the modified Dunn procedure plus postoperative stabilization techniques can be demonstrated as providing acceptable outcomes, they could become the preferred treatment for stable, chronic SCFE, Dr. Klingele believes, as they can restore normal anatomy and joint function unlike any other surgical option. He and the rest of the clinician-researcher team are now collecting data on long-term joint mobility and function for patients with SCFE.

“For patients with severe stable slips, outcomes from in situ screw fixation alone are not good, but we now also know that the modified Dunn procedure for these cases is different than using it for acute, unstable SCFE—you have to be more careful to avoid postoperative complications,” says Dr. Klingele. “If we can eliminate that additional risk, though, we will be on our way to reaching the ideal treatment outcome: minimal complications with the best long-term hip function.”

References:

  1. Persinger F, Davis RL 2nd, Samora WP, Klingele KE. Treatment of Unstable Slipped Capital Epiphysis Via the Modified Dunn Procedure. Journal of Pediatric Orthopedics. 2018;38(1):3-8.
  2. Davis RL 2nd, Samora WP 3rd, Persinger F, Klingele KE. Treatment of Unstable Versus Stable Slipped Capital Femoral Epiphysis Using the Modified Dunn ProcedureJournal of Pediatric Orthopedics. 2019;39(8):411-415.

Image credit: Nationwide Children’s