Historically, hamstring autografts for ACL reconstruction have been thought to be inferior to the patellar tendon or quad. Despite this fact, they continue to be used in a high percentage of ACL surgeries around the world. The reason for this is that we do see excellent outcomes using hamstring tendons.
In this large study (nearly 6,000 patients) from the Kaiser Permanente registry, they were able to show that patients whose graft was less than or equal to 8mm had a 32 percent higher failure rate. Large studies, such as this one, help us understand surgical failures and educate our patients on the optimal graft for their ACL surgery.
It is very rare that I see a hamstring graft that is 8 mm, as we can add the gracilis (a second hamstring) to the graft if need be. Every graft has a downside; weakening the hamstrings, patella, or quad is not without morbidity.
Read the article on ResearchGate to learn more about this study: Is There a Hamstring Autograft Diameter Threshold for Anterior Cruciate Ligament Reconstruction?
Image source: Wikimedia (edited slightly for size and content).