Introduction: The Persistent Challenge of ACL Failure in Youth
Anterior Cruciate Ligament (ACL) rupture remains one of the most common and impactful musculoskeletal injuries in sports medicine. While surgical reconstruction (ACLR) has long been the gold standard for restoring knee stability, the orthopedic community has faced a persistent challenge: high graft failure rates in young, active populations. Despite technical refinements and the use of various autografts, failure rates in patients under 25 years old can often exceed 10-15%, leading to significant morbidity and the need for complex revision surgeries.
In recent years, attention has shifted toward the role of the anterolateral complex of the knee. Biomechanical studies have suggested that isolated ACLR may not sufficiently control the internal rotatory instability that often accompanies high-grade ACL injuries. This has led to the revival and refinement of the Anterolateral Ligament Reconstruction (ALLR) as an adjunctive procedure. However, high-level clinical evidence comparing combined ACLR+ALLR against the traditional ‘gold standard’—the Bone-Patellar Tendon-Bone (BPTB) autograft—has been limited until now.
The Biomechanical Rationale: Why the Anterolateral Ligament?
The Anterolateral Ligament (ALL) acts as a secondary stabilizer to the ACL, particularly in resisting internal tibial rotation. When an ACL injury occurs, the ALL is frequently injured or stretched, leading to a ‘pivot-shift’ phenomenon that isolated intra-articular ACLR might not fully address. By performing a combined reconstruction, surgeons aim to restore both the primary sagittal stability (via ACLR) and the secondary rotatory stability (via ALLR). Historically, there were concerns regarding over-constraint of the lateral compartment, but contemporary anatomical reconstruction techniques have largely mitigated these risks.
Study Methodology: A Robust Comparative Framework
The study, conducted at the Santy Orthopedic Center in Lyon, France, was a prospective, single-center, randomized controlled trial. It included 593 patients aged 18 to 35 years with symptomatic ACL ruptures. These patients represent a high-risk group due to their age and activity levels.
Interventions and Randomization
Participants were randomly allocated in a 1:1 ratio into two groups:
- ACLR + ALLR Group: Combined reconstruction using hamstring tendon autograft.
- ACLR Group: Isolated ACL reconstruction using bone-patellar tendon-bone (BPTB) autograft.
The choice of BPTB as the comparator is significant, as it is traditionally considered the strongest graft option for young athletes. Randomization was performed with a block size of four using concealed allocation to ensure study integrity. While surgeons were informed of the procedure on the morning of the surgery, the outcome assessors—independent sports medicine physicians—remained blinded to the surgical specifics during the 5-year follow-up period.
Key Findings: Reducing the Risk of Failure
The primary endpoint was graft failure at 5 years, defined by clinical instability or MRI evidence of rupture. Of the 593 patients randomized, an impressive 94% (556 patients) completed the 5-year follow-up, providing high statistical power to the results.
Primary Outcome: Graft Failure Rates
The results demonstrated a significant superiority for the combined procedure:
- ACLR + ALLR: 4.2% failure rate (12 out of 283 patients).
- Isolated ACLR (BPTB): 10.3% failure rate (28 out of 273 patients).
The statistical analysis revealed an adjusted odds ratio of 2.54 (95% CI 1.27; 5.36, p = 0.008), indicating that patients who received only the BPTB reconstruction were more than 2.5 times more likely to experience graft failure compared to those who received the combined hamstring + ALL reconstruction.
The Number Needed to Treat (NNT)
One of the most clinically relevant metrics provided by this trial is the Number Needed to Treat (NNT). To prevent one graft failure, the NNT was 17 for the general study population. However, when focusing on the highest-risk subgroup—patients younger than 25 years—the NNT dropped to 9. This suggests that for every nine young patients undergoing the combined procedure instead of isolated BPTB reconstruction, one additional graft failure is prevented over five years.
Expert Commentary: Shifting the Treatment Paradigm
This study represents a landmark in sports medicine. For decades, the debate centered on whether hamstring or BPTB autografts were superior. This trial suggests that the debate may have been missing a crucial component: the lateral extra-articular stabilization. By using a hamstring autograft in conjunction with ALLR, surgeons achieved a failure rate significantly lower than that of the BPTB, which was previously considered the benchmark for stability.
Addressing Safety and Complications
A common concern with adding an extra-articular procedure is the potential for increased stiffness or hardware-related complications. However, the safety analysis in this trial showed that the combined procedure did not lead to a significant increase in adverse events. The use of hamstring tendons for both reconstructions also avoids the donor site morbidity often associated with BPTB grafts, such as anterior knee pain and kneeling discomfort.
Limitations and Future Directions
While the results are compelling, some limitations exist. This was a single-center study conducted by surgeons with extensive experience in ALL reconstruction, which may affect the generalizability of the results to centers with less experience in this specific technique. Additionally, while 5-year data is robust, the orthopedic community continues to seek 10-year and 15-year outcomes to assess the potential long-term impact on joint health and the development of osteoarthritis.
Conclusion: A New Standard for High-Risk Reconstructions?
The findings from the Santy Orthopedic Center provide strong evidence that for young, active adults, combining ACL reconstruction with anterolateral ligament reconstruction significantly improves graft survivorship. The reduction in failure rates is not only statistically significant but clinically transformative, particularly for patients under the age of 25. These results advocate for a shift in surgical planning: rather than simply choosing between graft types, surgeons should consider the patient’s risk profile and the potential benefits of restoring the anterolateral complex to ensure the best long-term outcomes.
Funding and Clinical Trial Information
This study was funded by GCS Ramsay Santé pour l’Enseignement et la Recherche. Trial registration: ClinicalTrials.gov, ID NCT03740022.
References
Sonnery-Cottet B, Carrozzo A, Poilvache H, Fayard JM, Freychet B, Thaunat M, Vieira TD, Saithna A; Santy Orthopedic Center Group. Anterior cruciate ligament reconstruction combined with anterolateral ligament reconstruction using hamstring autograft versus anterior cruciate ligament reconstruction using bone-patellar tendon-bone autograft: a randomised controlled trial with 5-year follow-up. Lancet Reg Health Eur. 2025 Dec 20;62:101561. doi: 10.1016/j.lanepe.2025.101561. PMID: 41536854.