Signs Your Prior ACL Reconstruction May Not Be Functioning
Patients who need revision surgery often report symptoms like their original ACL tear. Common signs include:
- Recurrent instability or “giving way” episodes
- A sense that the knee cannot be trusted during pivoting or cutting activities
- Pain with activity
- Recurrent swelling after sports
- Difficulty returning to prior level of activity
- A new injury followed by instability
Some patients experience a clear traumatic re-tear. Others develop gradual laxity over time due to graft stretching or technical factors.
If the knee feels unstable, it’s important to be evaluated early. Persistent instability can lead to additional damage to the meniscus and cartilage and increase the odds of post-traumatic arthritis.
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Why Do ACL Reconstructions Fail?
Understanding why a graft failed is critical to planning a successful revision surgery.
1. Technical Factors
One of the most common causes of ACL graft failure is improper tunnel placement. If the bone tunnels are not positioned anatomically:
- The graft may not restore normal knee mechanics
- The graft may stretch out over time
- Abnormal forces may predispose it to re-tear
Other technical causes include:
- Poor fixation (graft not secured adequately)
- Tunnel widening
- Inadequate graft tensioning
2. Graft Choice
Allograft (donor tissue) has been associated with higher failure rates in young, active patients compared to autograft (the patient’s own tissue). While allografts have a role in certain situations, they are generally not preferred for young athletes due to higher re-tear risk. Small diameter hamstrings grafts have also proven to have higher failure rates.
3. Trauma
A significant new injury can cause even a well-performed and rehabilitated reconstruction to fail. High-energy pivoting sports such as soccer, basketball, and skiing carry ongoing risk.
4. Unaddressed Associated Injuries
ACL reconstruction does not occur in isolation. If other stabilizing structures are injured and not addressed, the graft may be overloaded.
These include:
- Meniscus tears
- Posterolateral corner injuries (LCL)
- Medial collateral ligament (MCL) injuries
- Significant cartilage damage
- Generalized ligament hyperlaxity
Failure to address these can increase stress on the ACL graft.
5. Alignment Issues
Lower extremity alignment plays an important role. Excessive varus alignment (“bow-legged” alignment) or abnormal posterior slope of the tibia can increase forces across the ACL graft and increase failure risk. In select cases, corrective osteotomy may be recommended.
6. Returning to Sport Too Soon
Biologic graft healing takes time. Even if strength and motion recover quickly, graft incorporation continues for many months. Premature return to high-risk sports increases the likelihood of re-injury. Returning before 9 months to high level contact sports can be a risk factor for re-tear.
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Evaluation Before Revision Surgery
Revision ACL reconstruction begins with a comprehensive workup:
- Detailed history and physical examination
- Xrays
- Advanced imaging (MRI)
- CT scan to assess tunnel position and bone stock (in certain situations)
- Evaluation of limb alignment
- Assessment of meniscus, cartilage, and other ligaments
This evaluation helps determine whether a one-stage or two-stage revision is necessary.
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One-Stage vs. Two-Stage Revision ACL Reconstruction
One-Stage Revision
In many cases, revision can be performed in a single surgery. This is possible when:
- Previous tunnels are well positioned or can be avoided
- There is adequate bone stock
- No significant tunnel widening is present
In this scenario, the old graft is removed and new, anatomically positioned tunnels are created. We often can address some overlap and tunnel widening with one-stage bone grafting. 90% of revisions can be performed in a single surgery.
Two-Stage Revision
If prior tunnels are malpositioned, excessively widened, or overlapping with ideal new tunnel positions, a staged approach may be safer and more reliable.
Stage 1:
- Removal of old hardware
- Bone grafting of prior tunnels
- Allow time (typically 3–6 months) for bone healing
Stage 2:
- Definitive ACL reconstruction with new, properly positioned tunnels
While this requires patience, it creates a more stable foundation and improves long-term outcomes.
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Graft Choice in Revision Surgery
Whenever possible, I strongly prefer using autograft tissue (your own tissue) for revision ACL reconstruction.
Research consistently demonstrates:
- Lower failure rates
- Better graft incorporation
- Higher return-to-sport reliability
My preferred grafts in the revision setting are:
- Bone–patellar tendon–bone (BTB) autograft
- Quadriceps tendon autograft
These grafts provide excellent strength, reliable fixation, and robust healing characteristics. In revision surgery—where success margins are narrower—biologic healing matters even more.
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The Role of Anterolateral Augmentation (IT Band Tenodesis)
In revision ACL reconstruction, we often add a procedure to protect the new graft from rotational stress.
An anterolateral augmentation, commonly performed as an IT band tenodesis (sometimes called a lateral extra-articular tenodesis or LET), reinforces rotational control of the knee.
This additional procedure:
- Decreases rotational instability
- Reduces graft stress
- Lowers re-tear rates in high-risk patients
- Improves overall stability in revision cases
Patients who benefit most include:
- Young athletes
- Those returning to pivoting sports
- Patients with high-grade rotational laxity
- Individuals undergoing revision surgery
By addressing both central (ACL) and peripheral stability, we improve the durability of the reconstruction.
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Rehabilitation After Revision ACL Surgery
Rehabilitation after revision ACL reconstruction is thoughtful and criteria-based. While the overall timeline is similar to primary ACL surgery, progression may be slightly more cautious depending on:
- Associated procedures
- Meniscus repair
- Cartilage restoration
- Osteotomy
Return to pivoting sports typically occurs around 9–12 months and only after meeting strength, functional, and neuromuscular milestones.
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Our Philosophy: Identify the Cause, Correct All Contributing Factors
Revision ACL reconstruction is not simply “redoing” the original surgery. It requires:
- Identifying why the graft failed
- Correcting technical issues
- Addressing alignment
- Treating meniscus and cartilage injuries
- Optimizing graft choice
- Protecting the graft with adjunct procedures when appropriate
By taking a comprehensive, individualized approach, I aim to restore stability, protect the knee long-term, and safely return patients to the activities they love.
If you are experiencing instability after a prior ACL reconstruction, early evaluation is important. A carefully planned revision can restore confidence and help prevent further damage to the knee.
