2025 ISAKOS Biennial Congress Paper
Knee hyperextension is not associated with anterior knee laxity, subjective knee function or revision surgery after ACL reconstruction in children and adolescents
Frida Hansson, MD, Stockholm SWEDEN
Anders Stalman, MD, PhD, Associate Professor, Saltsjobaden, Sweden SWEDEN
Gunnar Edman, MD, PhD, Prof., Sollentuna, Sverige SWEDEN
Per-Mats Janarv, MD, PhD, Associate Prof., Stockholm SWEDEN
Eva Bengtsson Moström, MD, PhD, Stockholm SWEDEN
Riccardo Cristiani, MD, PhD, Associate Professor, Stockholm SWEDEN
Department of Molecular Medicine and Surgery, Stockholm Sports Trauma Research Center, Karolinska Institutet, Stockholm, SWEDEN
FDA Status Not Applicable
Summary
No association between knee hyperextension and anterior knee laxity, subjective outcome or revision surgery after ACLR in children and adolescents.
Abstract
Purpose
To evaluate whether contralateral knee hyperextension is associated with anterior knee laxity, subjective knee function or revision surgery after primary anterior cruciate ligament reconstruction (ACLR) in patients <18 years.
Methods
Patients <18 years who underwent primary ACLR at Capio Artro Clinic, Stockholm, Sweden between January 2002 and March 2017 were identified. They were dichotomised into a ‘hyperextension’ group (≤ –5°) and ‘no hyperextension’ group (> –5°) depending on pre-operative contralateral passive knee extension degree. Anterior knee laxity (KT-1000 arthrometer) was measured pre-operatively and 6 months post-operatively. The knee injury and osteoarthritis outcome score (KOOS) was collected pre-operatively and after 2 years. Revision ACLR within 5 years after primary ACLR was captured in the Swedish National Knee Ligament Registry.
Results
1250 patients (63.6% female [n=795]; mean age 15.5 ± 1.5 years) were included (hyperextension group: 52.9% [n=661]). Mean extension was –6.1° ± 2.2° in the hyperextension group and 0° ± 0.7° in the no hyperextension group. Hamstring autograft was used in 93.3% (1166 of 1250). No significant difference between the groups was seen in anterior knee laxity or in the rate of surgical failure at 6 months post-operatively (side-to-side difference: >5 mm) (hyperextension group, 6.6% [32 of 484 patients] vs. no hyperextension group, 6.8% [29 of 428 patients]; P=ns). Statistically significant but non-clinically relevant intergroup differences were seen in the KOOS Sport/Recreation and Quality of Life subscales after 2 years. The rate of revision ACLR within 5 years was 11.1% (119 of 1073 patients). The hazard for revision ACLR in the hyperextension group was not significantly different from the no hyperextension group (hazard ratio, 0.91; 95% confidence interval, 0.63-1.31; P=ns).
Conclusions
There was no significant association between preoperative passive contralateral knee hyperextension and anterior knee laxity, subjective knee function, or the risk of revision ACL surgery in paediatric patients. These findings suggest that knee hyperextension alone should not preclude the use of hamstring tendon grafts in children and adolescents undergoing ACL reconstruction. The study found a high rate of revision ACL surgery in this paediatric population.
Level of Evidence: Level of evidence III
Keywords
Knee hyperextension, ACL reconstruction, children, adolescents, revision, laxity