Revision ACL Reconstruction (Redo ACL Surgery)

Revision ACL surgery is one of the areas I am most frequently referred patients for. When a previous ACL reconstruction has failed – whether because of a new injury, a technical issue with the original surgery, or factors that were not addressed the first time – the knee often gives way again, and the patient is left wondering whether anything can be done. The answer is usually yes, but revision ACL reconstruction is genuinely more complex than a first-time operation. The key is understanding why the first graft failed, because without answering that question, the revision is at higher risk of failing too.

What is revision ACL reconstruction?

Revision ACL reconstruction means replacing or rebuilding the ACL after a previous reconstruction has failed. The goal is the same as primary surgery – restoring stability for walking, work, and sport, especially pivoting activities like football, rugby, netball, skiing, and court sports – but the path to getting there is more involved.

Depending on the state of the bone tunnels from the previous surgery, revision may be done as a single-stage operation or as a two-stage process where bone graft is used first to rebuild the tunnels before the definitive reconstruction.

Why ACL reconstructions fail

This is the question I spend the most time on in a revision consultation, because the answer drives the entire plan. Common reasons include:

New injury – a further twist, contact injury, or return to sport before the graft was ready
Tunnel position – if the original tunnels were not in the ideal location, the graft is under abnormal load from day one
Graft healing problems – biological failure where the graft did not incorporate properly
Meniscus deficiency – loss of meniscus tissue increases the load on the ACL graft significantly
Unaddressed rotational instability – some knees need a lateral extra-articular procedure in addition to the ACL, and without it the graft is overloaded
Alignment issues – increased tibial slope or varus/valgus malalignment can put excessive force through the graft
Rehabilitation factors – returning to sport with strength deficits, poor movement control, or before the graft is mature enough

Often it is a combination of factors rather than a single cause. Revision planning means identifying which of these contributed and addressing as many as possible.

Signs that your ACL graft may have failed

Recurrent giving way or a "shifting" sensation during turning or pivoting
Loss of confidence in the knee during sport or on uneven ground
Swelling after twisting events
Difficulty decelerating or changing direction
A persistent feeling that the knee is unstable or "just not right" despite rehabilitation

How I assess a revision ACL case

Revision ACL surgery should never be a repeat of the first operation with the same approach. I take time over the assessment because the decisions made here determine the outcome.

I want to know the full story: when symptoms returned, whether there was a specific injury, what sport you want to get back to, what graft was used originally, and what rehabilitation you did. On examination, I test stability in multiple directions – including rotational stability – and assess movement patterns and joint laxity.

Imaging is more extensive than for a primary ACL. X-rays show the existing tunnel positions and any fixation hardware. MRI assesses the graft itself, the meniscus, cartilage, and any other ligament damage. I almost always arrange a CT scan as well, because it gives a precise picture of tunnel size, position, and bone quality – information that is essential for planning whether a single-stage or two-stage approach is needed.

If alignment may be contributing – for example, if the tibial slope is steep or there is significant bow-leg – I assess that specifically, because it may need correcting at the same time as the revision.

Single-stage vs two-stage revision

Single-stage revision

When the previous tunnels are reasonably positioned and not excessively widened, I can often perform the revision in a single operation – removing the old graft, placing the new one, and addressing any associated problems at the same time.

Two-stage revision

If the existing tunnels are too large, in the wrong position, or would compromise the placement of new tunnels, I recommend a two-stage approach. The first stage involves removing old hardware and bone grafting the tunnels to rebuild bone stock. After a healing period (typically three to six months), the second stage is the definitive revision reconstruction.

Patients sometimes find the idea of two operations frustrating, but when the tunnels are the problem, staging is the safest route to a durable result. Cutting corners here risks a third failure.

Graft choices for revision surgery

Graft selection in revision ACL surgery is more nuanced than in primary surgery, because your previous graft has already been used and the options are partly determined by what remains available. I use autograft (your own tissue) whenever possible. Donor tissue (allograft) is an option I reserve for specific situations.

BTB (Bone-Patellar Tendon-Bone)

BTB is often my first choice for revision, particularly if it was not the graft used originally. The bone blocks provide strong fixation – which can be especially useful in revision settings where the bone environment may be less ideal – and it has a long track record in high-demand athletes. The trade-off is anterior knee discomfort and kneeling pain in some patients.

Hamstring tendon

Hamstring graft is an excellent option in revision cases, especially if the previous surgery used a different graft. If the hamstrings on the operated side have already been harvested, I can take them from the other leg (contralateral harvest) – something I discuss carefully, because it means some temporary symptoms in the donor knee.

Quadriceps tendon / rectus femoris

When previous harvest limits options or when I need a robust graft with a bone block, a graft from the quadriceps mechanism can work well. Rehabilitation after quad tendon harvest requires focused physiotherapy because it takes time for the quadriceps to regain full strength, but in the right patient it is a very good revision graft.

The key principle: graft choice is shaped by what has already been used, what remains available, and which option best fits your anatomy and sport demands. I discuss the trade-offs of each option in detail at your consultation.

Contralateral grafts (using the other leg)

Taking graft from the other knee is a genuinely useful option in revision surgery. I consider it when:

The operated knee has limited graft options after previous harvest
A strong autograft is preferred and the best tissue is on the other side
Using the contralateral side avoids re-operating in a previously harvested area

The practical reality is that you will have two knees recovering in the early weeks – though the donor knee typically recovers faster. I explain exactly what to expect so there are no surprises.

Addressing the factors that caused failure

Simply replacing the graft is not enough if the underlying reasons for failure are still present. Depending on your knee, I may combine the revision ACL with:

Meniscus repair or preservation – protecting what meniscus remains is critical for long-term graft survival and joint health
Cartilage treatment for focal defects
Lateral extra-articular tenodesis (LET) / anterolateral ligament reconstruction – I add this when there is significant rotational instability, which is common in the revision setting
Osteotomy if alignment is putting excessive load on the graft
Other ligament reconstruction (MCL, LCL/PLC, PCL) if additional instability is present

The aim is not just to replace the ACL but to create a knee environment where the new graft can survive long-term.

Recovery and rehabilitation

Recovery after revision ACL reconstruction is typically slower than after a first-time operation. The surgery is more extensive, there may be additional procedures to protect, and the biology of healing in a previously operated knee can be less predictable.

Rehabilitation priorities

Swelling control and regaining full extension early – this is just as critical in revision as in primary surgery
Progressive strength rebuilding (quadriceps, hamstrings, hips)
Movement retraining and neuromuscular control
Gradual return to running and sport-specific agility work when objective targets are met
Return to sport based on strength testing, functional performance, and confidence – not calendar dates

If I have performed additional procedures – meniscus repair, tenodesis, cartilage surgery, or osteotomy – your early rehabilitation will be modified to protect those repairs. I coordinate this closely with your physiotherapist.

Risks

Revision ACL reconstruction carries the standard surgical risks (infection, blood clots, wound problems) plus some that are more specific to the revision setting:

Stiffness or prolonged swelling – more common than in primary surgery
Persistent instability or re-failure of the graft
Donor-site discomfort depending on graft choice
Meniscus or cartilage damage that continues to affect the knee despite a stable ACL

I discuss the specific risks that apply to your situation and how we manage them through surgical planning and rehabilitation.

Frequently asked questions

Is revision surgery always needed if the graft fails?

No. Some people manage well with rehabilitation and activity modification, particularly if they do not play pivoting sport. I recommend revision when the instability is affecting daily life, work, or sport, or when the knee is at risk of further meniscus or cartilage damage from ongoing instability.

How do you choose the best graft?

I look at what was used previously, what tissue is still available, your tunnel situation, your sport demands, and whether additional procedures are planned. BTB is often my first choice in revision, but the best graft is the one that fits your specific scenario. I go through the options in detail at your appointment.

Will recovery be slower than my first ACL reconstruction?

Usually, yes. The surgery is more involved and often includes additional procedures. I use objective strength and function targets to guide return-to-sport decisions rather than fixed timelines, and the rehabilitation is structured around those goals.

Can I be referred for revision ACL assessment?

Yes – revision ACL is one of my main referral areas. I see patients referred by GPs, physiotherapists, sports medicine doctors, and other orthopaedic surgeons. You can also self-refer directly. I am happy to review your previous imaging and operation notes and advise on the best way forward.