When does an ACL tear need surgery?

Not every ACL tear requires reconstruction. Older, less active patients with isolated ACL injuries and stable knees can sometimes manage without surgery. However, for patients who want to return to pivoting sports, who have concomitant meniscus or cartilage injuries, or who experience recurrent giving way in daily activities, ACL reconstruction is generally recommended.

The decision is made on the basis of MRI findings, clinical examination (Lachman test, pivot-shift), your activity goals, and the presence of other injuries. I discuss this in detail at the first consultation.

Graft choice

ACL reconstruction requires a tendon graft to replace the torn ligament. The three main autograft (your own tissue) options are hamstring tendon (HT), bone-patellar tendon-bone (BPTB), and quadriceps tendon (QT). All three are well-studied.

What the evidence shows: A systematic review and meta-analysis (Mouarbes et al., Am J Sports Med, 2019) comparing all three graft types found no significant differences in knee stability, functional scores, or graft failure rates between HT, BPTB, and QT. However, QT autograft showed significantly less harvest-site pain than BPTB, and slightly better functional scores compared to HT. All three are appropriate choices — graft selection should be individualised based on anatomy, activity level, and surgeon experience.

My standard approach is hamstring tendon autograft for most patients, with quadriceps tendon as an alternative for patients with smaller hamstring tendons or specific anatomical considerations. For revision cases, allograft or quadriceps tendon is often preferred.

The surgery

ACL reconstruction is performed arthroscopically — through small incisions using a camera and instruments. The torn ligament is removed and a tunnel is drilled in both the femur and tibia to position the new graft in the anatomical ACL footprint. The graft is fixed with screws or buttons.

The procedure is performed under general or spinal anaesthesia. Meniscus tears, if present, are addressed at the same time.

Recovery milestones

PCL reconstruction

Posterior cruciate ligament (PCL) tears are less common than ACL tears and are often managed non-operatively in isolation. Surgical reconstruction is recommended for grade III PCL injuries, multi-ligament injuries, or persistent instability after conservative treatment. The principles are similar to ACL reconstruction — arthroscopic, graft-based, anatomical footprint restoration.

For complex instability involving the outer structures of the knee alongside a cruciate tear, see the article on posterolateral corner (PLC) reconstruction. For concurrent meniscus injuries, see meniscus surgery.

References (PubMed)

Mouarbes D, et al. Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Outcomes for Quadriceps Tendon Autograft Versus Bone-Patellar Tendon-Bone and Hamstring-Tendon Autografts. Am J Sports Med. 2019;47(14):3531–3540. DOI: 10.1177/0363546518825340