ACL Reconstruction — Hamstring Tendon Graft

Why this approach — at MOS

The hamstring graft occupies an important place in our ACL graft repertoire, particularly for patients who are active recreational athletes, have anatomy that does not favor patellar or quadriceps tendon harvest, or who present with specific functional demands around kneeling. We do not use it reflexively, and we do not recommend it for young competitive athletes in high-demand sports without a serious discussion of the failure-rate data and the role of LET augmentation.

For patients under 25 who are competitive athletes in pivoting sports and who, for appropriate reasons, are receiving a hamstring graft, we strongly recommend adding LET. The STABILITY trial data is unambiguous: adding a modified Lemaire LET to hamstring ACL reconstruction reduced graft rupture by 67% (from 11% to 4%) in young, high-risk patients. This is not a marginal benefit — it is a clinically significant reduction in a catastrophic outcome.

We also pay close attention to graft diameter. A quadrupled hamstring graft below 8 mm in diameter has been associated with higher failure rates in the literature. If anatomy predicts a small-diameter graft, we discuss alternatives: using the gracilis in addition to the semitendinosus, adding tape augmentation, or switching to a different autograft source.

Our physical therapists in Germantown have specific experience with post-hamstring-harvest ACL protocols and monitor hamstring-quadriceps ratio throughout rehabilitation, recognizing that hamstring harvest creates an asymmetry that must be addressed before return to sport.

Who is a candidate?

Indications

• Active patients with complete ACL tear who want an autograft option with lower anterior knee morbidity than patellar tendon
• Patients whose activities or occupation involve kneeling and who want to avoid BPTB anterior knee pain
• Patients with anatomy unfavorable for patellar tendon or quadriceps tendon harvest
• Recreational athletes (rather than competitive high-demand athletes) where the lower failure rate advantage of BPTB is less critical
• Patients undergoing hamstring graft with LET augmentation — a well-supported combination for high-risk patients per the STABILITY trial

Contraindications / Less Preferred Situations

• Young competitive athletes (under 20) in high-demand cutting and pivoting sports — evidence consistently shows higher failure rates with hamstring graft in this population compared to BPTB; LET augmentation is strongly recommended if hamstring graft is used
• Patients with small semitendinosus tendons or predicted graft diameter under 8 mm — smaller diameter grafts have higher failure rates; augmentation strategies or a different graft type should be considered
• Patients with prior hamstring harvest on the same knee — the tendon does partially regenerate, but re-harvest is less reliable
• Patients in whom hamstring deficit is particularly problematic (sprinters, hamstring-dominant athletes) — the hamstring-quadriceps ratio impact of harvest should be discussed

Conservative Treatment First

ACL reconstruction is not the automatic recommendation for every patient with a torn ACL. Lower-demand patients — those who are not involved in pivoting sports and who are functionally stable in daily life — often do well with a structured physical therapy program. At Maryland Orthopedic Specialists, the decision to proceed with reconstruction begins with a detailed assessment of activity demands, functional instability, and associated injuries. Surgery is recommended when the patient's goals and knee examination indicate that non-surgical management is unlikely to provide adequate stability.

When hamstring autograft is selected, the surgical plan also includes a discussion of LET augmentation for appropriate patients — a decision informed by age, activity level, and examination findings.

The procedure

What Is ACL Reconstruction with a Hamstring Tendon Graft?

Hamstring tendon ACL reconstruction uses the semitendinosus tendon — and often the gracilis — harvested from the inner side of the knee, folded to create a quadrupled graft bundle. It offers lower anterior knee morbidity than patellar tendon harvest, a smaller incision, and reliable outcomes across a broad patient population, though evidence shows higher failure rates than bone-patellar tendon-bone graft in young, high-demand athletes.

The semitendinosus and gracilis are two of the three tendons that insert at the pes anserine on the medial surface of the proximal tibia. Both tendons can be harvested through a small incision on the inner side of the knee. After harvest, the tendons are prepared on the back table: each is doubled over, creating a four-strand (quadrupled) bundle that achieves a diameter typically between 8 and 10 mm, depending on the patient's anatomy. This bundled configuration is what gives the graft its composite strength.

Unlike the patellar tendon graft, the hamstring graft is entirely soft tissue — there are no bone plugs at the ends. This means fixation relies on sutures, interference screws, and cortical buttons rather than direct bone-to-bone contact. Soft-tissue-to-bone healing takes longer than bone-to-bone healing (12–16 weeks compared to 6–8 weeks for BPTB), which influences the early phases of the rehabilitation protocol.

The hamstring graft is the most commonly used ACL graft in many parts of the world, particularly in Europe and Australia. Its popularity reflects genuine advantages: smaller incisions, avoidance of anterior knee pain, and consistent clinical outcomes in the general ACL population. Its limitations are most pronounced in a specific subset of patients — young, high-demand athletes — where data consistently shows a higher failure rate compared to BPTB autograft.

What Happens During Hamstring Tendon ACL Reconstruction?

The procedure is performed as an outpatient surgery under general or spinal anesthesia.

Step 1 — Graft harvest. A small incision approximately 2–3 cm is made on the inner side of the knee, just below and behind the tibial tubercle, over the pes anserine. The semitendinosus tendon is identified and stripped from its muscle belly using a closed tendon stripper that slides proximally along the tendon. The gracilis tendon is harvested the same way if a larger graft diameter is needed. Both tendons are cleaned of muscle and connective tissue, then doubled over on themselves and secured with whip-stitch sutures to create a four-strand bundle. Graft diameter is measured; for grafts under 8 mm, the surgeon may consider tape augmentation or a modified graft preparation strategy.

Step 2 — Arthroscopic inspection. Arthroscopic portals allow complete inspection of the knee. Meniscal tears, cartilage damage, or other associated pathology is addressed before graft placement.

Step 3 — Tunnel drilling. Bone tunnels are drilled at the anatomic ACL footprints in the tibia and femur. Femoral tunnel placement via an anteromedial portal ensures true anatomic positioning.

Step 4 — Graft passage and fixation. The quadrupled graft is passed through the tibial tunnel and up into the femoral tunnel using a passing suture. The femoral end is fixed with a cortical button (suspensory fixation) that flips on the outer femoral cortex. The tibial end is fixed with an interference screw. Combined fixation techniques may be used for additional security.

Step 5 — LET augmentation (if indicated). For patients who meet high-risk criteria — age under 25, significant pivot-shift, desire to return to high-level pivoting sport — a lateral extra-articular tenodesis is added during the same anesthetic. The STABILITY trial demonstrated that LET added to hamstring ACL reconstruction reduces graft rupture by 67% in this population. This is a routine addition in appropriately selected patients at MOS.

Step 6 — Closure. Incisions are closed, a compressive dressing and hinged brace applied, and patients go home the same day.

Recovery timeline

Frequently Asked Questions