Partial Transphyseal All-Inside Anterior Cruciate Ligament Reconstruction in Skeletally Immature Adolescent Patients: Two-Year Minimum Follow-up Clinical and Radiologic Results

Abstract

Background: Anterior cruciate ligament (ACL) injuries in pediatric and adolescent populations have seen an uptick due to increased competitive sports participation. Treatment paradigms have shifted from nonoperative management to early reconstruction to prevent meniscal and cartilage damage. However, no consensus exists on the optimal reconstruction technique, particularly in skeletally immature patients.

Purpose/hypothesis: The purpose of this study was to evaluate the efficacy and safety of a limited transphyseal all-inside ACL reconstruction (ACLR) technique, hypothesizing that it would yield favorable clinical results without growth disturbances, graft failure, or complications at minimum 2-year follow-up.

Study design: Case series; Level of evidence, 4.

Methods: Consecutive patients aged between 10 and 18 years undergoing ACLR at Sant'Andrea University Hospital of Rome from January 2015 to June 2021 were enrolled. Exclusion criteria were closed physes, previous knee surgeries, and multiligament injuries. The limited transphyseal all-inside technique was used to minimize physeal damage during ACLR by carefully controlling tunnel size, orientation, and depth. Patients underwent standardized follow-ups at 2 and 6 weeks and at 3, 6, 12, and 24 months postoperatively. In addition, all patients were recalled for a final evaluation between February and August 2023. The final assessment included a physical examination (range of motion, pivot shift, Lachman test, Rolimeter-measured laxity, limb-length discrepancy, and deformity) and completion of patient-reported outcome measures (PROMs). Postoperative longstanding anteroposterior radiographs were obtained to evaluate radiographic growth disturbance. A comprehensive magnetic resonance imaging (MRI) assessment was performed by measuring the signal-to-noise quotient (SNQ), tunnel widening, graft healing, and graft maturity.

Results: Overall, 24 patients met inclusion criteria, with a mean age of 14.2 years. At a mean follow-up of 53.1 months (range, 28-90), the graft rupture rate was 12.5%, and the contralateral ACL rupture rate was 8.3%. Overall, the incidence of growth disturbances was 15.8% in patients who underwent radiologic evaluation. These included cases of angular deformity of >5° or limb-length discrepancy of >10 mm. The mean limb-length discrepancy was 0.31 cm, with no significant differences in limb alignment. MRI analysis revealed a mean tibial tunnel widening of 5.1%, and the mean SNQ was 2.85 ± 0.91 (range, 1.5-4.4). Graft maturity, assessed using the Howell grading system, was classified as grade 1 in 50% of patients and grade 2 in the remaining 50%, while graft healing was graded as 1 in 60% and 2 in 40%; in both, lower grades indicated better results. PROMs showed high scores for Knee injury and Osteoarthritis Outcome Score, International Knee Documentation Committee, and Lysholm scales, with a postoperative median Tegner activity scale score of 7. All patients returned to sports activities.

Conclusion: Limited transphyseal all-inside ACLR in skeletally immature patients demonstrated promising clinical outcomes and a low rate of significant growth disturbances, suggesting that it is an effective and safe technique for this population.

Keywords: ACL reconstruction; all-inside technique; growth disturbances; skeletally immature.

Figure 1.

Illustration of the measurements performed on radiograph. MAD, mechanical axis deviation; LDFA, mechanical lateral distal femoral angle; MPTA, medial proximal tibial angle.

Figure 2.

Example magnetic resonance imaging (MRI) of tunnel-widening calculations 12 months after anterior cruciate ligament reconstruction. The mean area at each tibial tunnel entrance was measured on oblique MRI perpendicular to the tunnel cross section.

Figure 3.

The study flowchart in line with the Strengthening the Reporting of Observational Studies in Epidemiology statement (http://www.strobe-statement.org). ACL, anterior cruciate ligament; ACLR, ACL reconstruction.

Figure 4.

Kaplan-Meier survival plot demonstrating graft survivorship. x-axis, follow-up time in months; y-axis, cumulative survival.

Figure 5.

Percentage (blue) of patients who achieved the Patient Acceptable Symptom State according to Muller et al and mean values (orange) of Knee injury and Osteoarthritis Outcome Score (KOOS) subscales and International Knee Documentation Committee (IKDC).