ACL reconstruction in pediatric patients yielded small changes in coronal plane alignment
Key takeaways:
- Small changes in coronal plane alignment were found after ACL reconstruction in pediatric patients.
- Guided growth may be considered for patients who need alignment correction at the time of ACL reconstruction.
Results presented here showed minimal changes in coronal plane alignment after physeal-sparing and transphyseal ACL reconstruction in patients with more than 2 years and 2 or less years of growth left, respectively.
“We have to respect the growing skeleton, and these ACL reconstruction techniques do a good job, but there is still a small percentage of patients who will have changes in their leg alignment after surgery,” Peter D. Fabricant, MD, MPH, associate professor of orthopedic surgery at Hospital for Special Surgery, told Healio about results presented at the Pediatric Orthopaedic Society of North America Annual Meeting. “It is important to know that for informed consent, for monitoring and, potentially, for intervention.”
ACL reconstruction
As part of the PLUTO study group, Fabricant and colleagues prospectively collected data from 99 skeletally immature patients with 2 or less years of remaining growth who underwent primary transphyseal, all soft-tissue autograft ACL reconstruction and from 112 prepubescent patients with more than 2 years of growth remaining who underwent either iliotibial band ACL reconstruction or all-epiphyseal ACL reconstruction. Researchers documented skeletal age within 3 months of surgery, as well as preoperative and 1-year postoperative standing radiographs for all patients.
Researchers assessed mechanical axis deviation, anatomic lateral distal femoral angle, mechanical medial proximal tibial angle, posterior tibial slope and leg length discrepancy for both the involved and uninvolved limbs.
“One of the important features of the methods was we compared the changes in the operative leg to changes in the nonoperative leg resulting from normal skeletal growth,” Fabricant said. “As kids are growing, the leg is growing and it can be changing shape naturally as kids are approaching maturity. Our main outcome was the difference of differences between the legs. If the right leg was the one that had the ACL reconstruction, how does that change compared with the left leg? We did that within each patient so that we did not just look at postoperative changes, we looked at those changes that were attributable to the surgery.”
Difference of differences
Among patients with 2 or less years of remaining growth who underwent primary transphyseal, all-soft tissue autograft ACL reconstruction, Fabricant and colleagues found small median difference of differences values in mechanical axis deviation, anatomic lateral distal femoral angle, mechanical medial proximal tibial angle and leg length discrepancy.
Despite these results, 29% of patients had 10 mm or greater change in mechanical axis compared with the nonoperative leg. Results also showed 17% and 16% of patients had a change in difference of differences by 5° or more for anatomic lateral distal femoral angle and mechanical medial proximal tibial angle, respectively. Researchers found no growth-related complications requiring intervention in any patients.
For patients with more than 2 years of growth remaining who underwent either iliotibial band ACL reconstruction or all-epiphyseal ACL reconstruction, results showed no difference of differences between the surgical technique groups for any radiographic parameter.
Although Fabricant and colleagues reported small median difference of differences values, 27% of patients had 10 mm or greater change in mechanical axis compared with the nonoperative leg. Researchers also found 27% of patients had a 5° or greater difference of differences for anatomic lateral distal femoral angle and 13% with an affected medial proximal tibial angle.
Guided growth
Fabricant told Healio these results may provide evidence for consideration of the use of guided growth — a procedure that allows correction of alignment of the knee.
“Although we did not look directly at guided growth, there is awareness for surgeons to, in addition to monitoring patients closely, potentially intervene at the time of surgery to correct the underlying coronal plane alignment, as it may get slightly worse in a subset of patients,” Fabricant said.
But he said more research is needed on when guided growth might come into play and the impact it may have on these patients.
“Is there an objective threshold at which we would consider guided growth, either at the time of surgery or if you notice changes? That is where this is all heading,” Fabricant said. “This does not change the fact that kids are tearing their ACLs at an alarming rate, it does not change the fact that these are the best surgeries for the growing skeleton but it can change how we talk to patients and families from the informed consent perspective and how we might intervene at the time of surgery with modifying patients’ alignment.”