Estimation Failure Risk by 0.5-mm Differences in Autologous Hamstring Graft Diameter in Anterior Cruciate Ligament Reconstruction: A Meta-analysis

Abstract

Background: Because grafts are made in 0.5-mm increments clinically for anterior cruciate ligament (ACL) reconstruction, it is important to clarify how the failure rate decreases as the diameter increases. Moreover, it is important to know whether even a slight increase in the graft diameter decreases the risk of failure. Hypothesis: The risk of failure decreases significantly with each 0.5-mm increase in hamstring graft diameter. Study Design: Meta-analysis; Level of evidence, 4. Methods: The systematic review and meta-analysis have estimated the diameter-specific failure risk for each 0.5-mm increase in ACL reconstruction using autologous hamstring grafts. We searched for studies describing the relationship between graft diameter and failure rate published before December 1, 2021, in leading databases, such as PubMed, EMBASE, Cochrane Library, and Web of Science, according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We included studies using single-bundle autologous hamstring grafts to investigate the relationship between failure rate and graft diameter of 0.5-mm intervals with >1-year follow-up. Then, we calculated the failure risk caused by 0.5-mm differences in autologous hamstring graft diameter. Assuming Poisson distribution for the statistical model, we employed an extended linear mixed-effects model in the meta-analyses. Results: Five studies containing 19,333 cases were eligible. The meta-analysis revealed that the estimated value of the coefficient of diameter in the Poisson model was −0.2357 with a 95% CI of −0.2743 to −0.1971 ( P < .0001). With every 1.0-mm increase in diameter, the failure rate decreased by 0.79 (0.76-0.82) times. In contrast, the failure rate increased by 1.27 (1.22-1.32) times for each 1.0-mm decrease in diameter. The failure rate significantly decreased with each 0.5-mm increase in graft diameter in the range of <7.0 to >9.0 mm from 3.63% to 1.79%. Conclusion: The risk of failure decreased correspondingly with each 0.5-mm increase in graft diameter in the range of <7.0 to >9.0 mm. Failure is multifactorial; however, increasing the graft diameter as much as possible to match each patient’s anatomic space without overstuffing is an effective precaution that surgeons can take to reduce failures.

A hamstring autograft diameter ≤ 8 mm is a safe option for smaller, lighter and female athletes who want to return to pivoting sports after ACL reconstruction

“…Although these results do not align with previous registry‐based studies evaluating the association between hamstring autograft diameter and ACL graft failure rates [6, 8, 12–14, 18, 20, 22, 23, 25, 26], they do support the proposal of Wang et al who state that hamstring autograft diameter should be selected according to the dimensions of the native ACL [27]. This is because athletes in the ≤ 8 mm group were smaller, lighter, and more often female, without having an increased risk for ACL graft failure.…”

“…According to most of the large ACL registry‐based cohort studies, hamstring autograft diameter is associated with the risk of ACL graft failure [6, 8, 11–14, 17, 18, 20, 22, 23, 25, 26, 29]. A hamstring graft diameter equal to or smaller than 8 mm is believed to increase ACL graft failure rates compared to grafts larger than 8 mm [6, 8, 13, 14, 18, 26].…”

No difference in revision risk between autologous hamstring graft less than 8 mm versus hybrid graft 8 mm or larger in anterior cruciate ligament reconstruction

“…However, due to iatrogenic suboptimal harvest or anatomical variation, the graft can be smaller than preferred [5]. While consensus on the minimum HA graft diameter needed to reduce the risk of graft failure is lacking [8], an inverse association between graft diameter and risk of failure and revision has been reported with most considering a diameter of ≥ 8 mm as the preferred minimum diameter [1, 9, 25]. There are several options for the surgeon when faced with a harvested HA with a diameter < 8 mm.…”

Though five‐strand hamstring autografts demonstrate greater graft diameter, postoperative outcomes are equivocal to four‐strand hamstring autograft preparations: a systematic review and meta‐analysis of level I and II studies

“…The hamstring autograft is a very commonly utilized option, with the beneits of having a greater load to failure compared with the patellar autograft and comparable short-term and mid-term clinical outcomes to the quadriceps tendon [35]. However, a signiicant drawback of using the hamstring tendon for ACLR is the unpredictable graft diameter that can be achieved intraoperatively, which is especially important considering several studies have recommended using a minimum graft diameter of 8 mm to avoid risk of future graft rupture [1,17,18,36].…”