ACL Surgery: Hamstring, Patellar Tendon or Donor Graft?

ACL ruptures are one of most widely talked about injuries, due to their debilitating nature and lengthy return to play times. ACL tears account for between 20 and 50% of ligamentous knee injuries in athletes and their impact goes far beyond the physical side, often times causing psychological and social struggles amongst athletes. Due to its key role in providing stability to the knee joint, more often than not, athletes will opt to have it surgically repaired, although conservative rehabilitation has gained more attention over the past few years. A question that frequently arises with ACL repair is what is used to repair/replace the ligament? In majority of cases it is either a Patellar Tendon Graft (taken from the tendon below your kneecap), Hamstring Tendon Graft (taken from the hamstring tendon at the back of the leg towards the knee) or a Donor Graft (an external graft, taken from a source outside of the patients body, usually a tendon/tissue from someone elses body). You may be wondering if there is a difference between grafts, pros and cons of each and ultimately which is the best option.

Let's take a look!

Non-surgical approach in the management of ACL injuries and how effective it may be.

For years, ACL tears were almost automatically treated with reconstruction surgery. However, growing evidence suggests that surgery is not always necessary.

Several high-quality studies have found that structured rehabilitation can produce outcomes comparable to ACL reconstruction for many individuals, particularly those who do not participate in high-level pivoting or contact sports (Frobell et al., 2010; Frobell et al., 2013). In simple terms, strength, function, quality of life, and long-term knee symptoms can be similar in patients who undergo comprehensive rehabilitation programmes compared to patients who take a surgical approach.

Stability is key! Some people are able to regain sufficient muscular control and neuromuscular function to return to their sport or hobby without significant instability. Others continue to experience episodes of the knee “giving way,” making surgery a more appropriate option (Beard et al., 2022). This will be case and patient dependant.

Research also suggests that non-operative management does not appear to increase the risk of osteoarthritis compared with reconstruction, although repeated instability episodes may increase the risk of secondary meniscal injury (Frobell et al., 2013).

An ACL tear is no longer viewed as a one-size-fits-all surgical problem. For the right patient—especially those willing to commit to rehabilitation and who do not require elite-level cutting and pivoting movements—non-operative management can be a legitimate, evidence-based treatment option (Frobell et al., 2010; Beard et al., 2022).

One argument for choosing a surgical approach compared to a conservative one would be guarantee. With an ACLR, the patient knows that their ligament has been repaired and can work accordingly. In a conservative approach, if the patient begins their rehabilitation journey and the knee still doesn’t feel right they may then decide to undergo surgery. Although their function pre-op will be good, it can prolong the entire process.

The Surgical Procedure for ACL reconstruction

It may be worth understanding the surgical process itself first.

ACL reconstruction is most often performed arthroscopically, using small incisions and a camera inserted into the knee joint. This technique ensures the tissues around the knee are preserved as well as they can be, and in turn helps with wound healing and limiting complications post op.

The procedure generally begins with the removal of the torn ACL remnants. The surgeon then prepares the graft tissue and creates small tunnels in the femur (thigh bone) and tibia (shin bone). These tunnels allow the graft to be positioned in the same orientation as the original ligament and provide stability in the same way that the old ACL once did.

Once the graft is threaded through the tunnels, it is secured using screws, buttons, or other fixation devices. Proper placement and tensioning of the graft are critical to restoring knee stability and normal movement mechanics.

After confirming the knee’s range of motion and stability, the incisions are closed and the patient is taken to recovery. Most ACL surgeries are completed within one to two hours and are performed as outpatient procedures, meaning patients usually return home the same day.

Early Recovery After Surgery

The first few days after ACL reconstruction focus on controlling pain and swelling while protecting the new graft. Patients commonly use crutches and may wear a knee brace depending on the surgeon’s protocol and whether additional procedures — such as meniscus repair — were performed.

Elevation, ice therapy, and gentle movement exercises are introduced early to prevent stiffness and encourage circulation. One of the immediate rehabilitation goals is regaining full knee extension, or the ability to completely straighten the leg.

Physical therapy often begins within days of surgery.

Rehabilitation and Physical Therapy

Rehabilitation is a crucial part of ACL recovery and often determines the overall success of the surgery. Recovery is gradual and typically occurs in stages over several months. It is important to take a progression criteria approach rather than a timing approach. Everybody is different and therefore no ACL recovery and rehabilitation should look the same. Focus on hitting objective markers and progress accordingly! Here is what a general ACL rehabilitation programme will look to target:

Phase 1: Restoring Movement and Reducing Swelling

During the first few weeks, physiotherapy focuses on reducing inflammation, restoring knee motion, and reactivating muscles that are prone to weakening/shutting down after surgery — especially the quadriceps. Patients begin gentle strengthening exercises, balance work, and gait re-education (walking practice).

Phase 2: Strength and Stability Training

As healing progresses, rehabilitation typically becomes more intensive. Exercises are introduced to strengthen the quadriceps, hamstrings, glutes, and core muscles that support knee function. The stationary bike is commonly utilised in this phase of rehabilitation, as well as swimming to maintain cardiovascular fitness and common strengthening exercises such as squats, step ups and lunges are commenced. Balance and motor control exercises are also introduced here.

Phase 3: Functional and Sport-Specific Training

Several months into recovery, patients begin more dynamic activities such as jogging, jumping, pivoting drills, and agility work. These exercises help prepare the knee for higher physical demands and reduce the risk of reinjury.

Athletes often complete sport-specific rehabilitation tailored to the movements required in their particular sport.

The Evidence:

While surgery and rehabilitation is quite consistent depending on the graft used, what does the research say about graft longevity and outcomes depending on the graft post ACL surgery?

When looking at the evidence, it seems that each graft type does come with its advantages and disadvantages, with some of these being more overpowering and relevant than others. Things like muscle weakness, graft survival rates, patient age and invasiveness are all factors that differ between grafts.

Patellar Tendon Graft vs Hamstring Graft:    

A couple of recent large systematic reviews (Samuelson 2017, Connors 2025) have compared the efficacy of hamstring grafts compared to BPTB (bone patellar tendon bone) grafts. A number of different outcomes were reviewed including graft survival rate, objective knee stability and donor site pain/morbidity.

In general BPTB grafts showed the most longevity compared to hamstring grafts, with a reduced re-rupture rate being shown in both of the above studies. Although the difference was significant in the 47,613 studies by Samuelson et al. the absolute difference was relatively small when comparing group here.

Overall patient reported satisfaction and knee function was similar between grafts, with patients receiving a hamstring graft understandably experiencing less anterior knee pain and kneeling pain in these studies.

So, to summarize between these:

BPTB Graft:

Pros:

• maximum graft stability

• lowest re-tear risk

• high-demand sport

Cons:

• more anterior knee pain

• kneeling pain

  
  

Hamstring Autograft

Pros:

• less kneeling pain

• less anterior knee pain

• Good overall outcomes

Cons:

• slightly higher laxity/re-tear risk in some studies

Donor Graft (Allograft)

Unfortunately, we do not have as much research comparing allografts (donor grafts) to hamstring and patellar tendon grafts in the research, but the research still includes studies of the efficacy of these types of grafts and some pros and cons of same.

A systematic review by Haybäck et al. found that allografts had higher revision and graft failure rates than autografts, particularly in younger athletic populations (Haybäck et al., 2022). Therefore, it may be said that allografts wouldn’t be as suitable in the younger, athletic population when compared to the other two graft types. Where the allograft may be more suitable would be in a patient who sustains an ACL injury in their older years or when they have retired from their sport and are engaging in lower risk and intensity exercise. Although it may not be most suitable for younger athletes, it does come with its pros, such as a less invasive technique, preservation of other tissues and in turn a significantly decreased chance of anterior knee/tendon pain post-op compared to the other two techniques.

Best supported for:

• older or lower-demand patients

• easier early recovery

Cons:

• higher failure risk in younger active people

Take Home Message

As previously mentioned, the surgery will repair the torn ligament. Each type of graft has their pros and cons and it can be important to weigh this up and discuss this with your surgeon pre-op to ensure what may be best for you. It is everything that follows that will ultimately be key to ensuring you have a safe and guided return to play and ultimately reduce your re-injury risk for the future.

The most important predictor of outcome is often not the graft itself, but:

• surgical technique

• rehab quality

• return-to-sport timing

• strength recovery

• avoiding return before neuromuscular recovery is complete

Whether you are considering surgery, preparing for ACL reconstruction, or currently progressing through ACL rehabilitation, our team can help guide your recovery through evidence-based physiotherapy treatment and sports rehabilitation.