Anterior cruciate ligament (ACL) injuries are common, particularly among athletes. While primary ACL reconstruction surgery is often successful, a significant number of patients require a second surgery, known as revision ACL reconstruction, to address graft failure or recurrent instability. This blog post aims to provide a comprehensive understanding of revision ACL surgery, including the procedure itself, factors influencing its success rate, and what patients can expect during the process.
What is ACL Revision Surgery?
ACL revision surgery is a second operation performed to repair a torn anterior cruciate ligament after a previous ACL reconstruction has failed. Primary ACL reconstructions may be performed using different techniques, so the surgeon doing the revision must take multiple factors into account when planning for this more complex procedure. About 200,000 ACL ruptures occur in the United States annually, and roughly 10% of patients who undergo a primary ACL reconstruction experience failure. When ACL surgery fails, surgeons must perform a revision surgery to reconstruct the torn ACL graft. If a repaired ACL fails, it can only be revised with an ACL reconstruction.
Why ACL Revisions Are Necessary
Several factors can contribute to the failure of an initial ACL reconstruction, leading to the need for revision surgery. These include:
- Technical errors: Improper graft placement, inadequate fixation, or incorrect tunnel positioning can compromise the stability of the reconstructed ACL.
- Graft failure: The new ACL graft may tear or stretch over time, especially if the patient returns to sports too soon or experiences a new injury.
- Infection: Although rare, infection can weaken the graft and surrounding tissues, leading to failure.
- Non-compliance with rehabilitation: Inadequate adherence to the prescribed rehabilitation program can hinder healing and increase the risk of re-injury.
- Unrecognized or untreated injuries: Failure to address other knee injuries, such as meniscus tears or posterolateral corner injuries, can place additional stress on the ACL graft and lead to failure.
- Alignment issues: Coronal and sagittal plane malalignment, as well as excessive tibial slope, can also lead to ACL graft failure.
Indications for Revision ACL Surgery
Patients may need revision ACL reconstruction if they experience the following:
- Recurrent instability: The knee feels unstable or gives way during activity, even after completing rehabilitation.
- Pain and swelling: Persistent pain and swelling in the knee, especially after activity.
- Limited range of motion: Difficulty fully straightening or bending the knee.
- New injury: A new injury to the knee that causes additional damage to the reconstructed ACL.
Diagnosing ACL Graft Failure
A thorough evaluation is essential to determine the cause of ACL graft failure and plan the revision surgery. This typically includes:
- Physical examination: A comprehensive assessment of knee stability, range of motion, and overall function.
- Imaging studies: X-rays, MRI, and CT scans to evaluate graft integrity, tunnel position, alignment, and any associated injuries.
- Stress X-rays: Used to identify unrecognized or untreated MCL or posterolateral corner injuries.
What specific imaging tests are typically required before a revision ACL surgery?
Before a revision ACL surgery, several imaging tests are typically required to assess the anatomical factors that could influence the outcome of the procedure. These tests help in evaluating the cause of the primary ACL failure, planning the revision surgery, and identifying any associated injuries.The common imaging techniques include:
- Standard Radiography: Weight-bearing X-rays of the lower limbs in two projections are taken to assess mechanical axis deviations. Special views like Rosenberg and Merchant views help evaluate the tibio-femoral and patellofemoral joints, respectively. Plain radiographs can also evaluate the tibial slope and detect any associated fractures.
- Magnetic Resonance Imaging (MRI): MRI is valuable for assessing the status of the ACL graft, detecting joint instability, and identifying any impingement or combined meniscal, cartilage, or ligament injuries. MRI can also reveal indirect signs of ligament injury, such as fluid diffusion or bone bruising.
- Computed Tomography (CT) Scan: CT scans are used to evaluate and quantify rotatory instability, especially in patients with associated posterolateral injury. CT scans help decide whether the revision should be performed as a single-stage or two-stage procedure and whether bone grafts will be needed. 3D reconstruction images from CT scans are often used for pre-operative planning. Hip-to-ankle AP X-rays are obtained to assess coronal plane malalignment, and single leg knee-to-ankle lateral X-rays are used to assess sagittal plane malalignment and tibial slope.
What additional procedures might be necessary based on imaging findings in revision ACL surgery?
Specific imaging tests typically required before a revision ACL surgery include:
- Alignment X-rays: Full-length alignment radiographs are used to assess mechanical axis deviations. Alignment X-rays, along with lateral knee X-rays, are also used to evaluate tibial slope.
- Lateral Radiographs: Used for assessing sagittal plane malalignment and tibial slope.
- 45-degree Flexion Weight-Bearing Postero-Anterior Radiographs: Radiographs taken at a 45-degree flexion with weight-bearing, as well as patellofemoral radiographs are typically required.
- Varus or valgus stress X-rays: They may be used if there is an unrecognized or untreated MCL or posterolateral corner injury.
The ACL Revision Procedure
ACL revision surgery is typically performed arthroscopically using small incisions. Depending on the complexity of the case, the procedure may be done in one or two stages.
Single-Stage Revision:
In a single-stage revision, the surgeon addresses all issues during one operation. This may involve:
- Graft removal: Removing the failed ACL graft.
- Bone grafting: Filling any enlarged or misplaced tunnels with bone graft to create a solid foundation for the new graft.
- Graft selection: Choosing a new graft to replace the torn ACL. Options include autografts (tissue from the patient’s body, such as the patellar tendon or hamstring tendons) or allografts (tissue from a donor).
- Graft placement: Positioning and securing the new graft in the correct location.
- Addressing other injuries: Repairing or reconstructing any associated injuries, such as meniscus tears or cartilage damage.
Two-Stage Revision:
In some cases, a two-stage approach may be necessary. This involves:
- Stage 1: Addressing any underlying issues, such as bone defects, malalignment, or infection. This may involve bone grafting, osteotomy (realignment of the bone), or debridement (removal of infected tissue).
- Stage 2: Performing the ACL reconstruction after the underlying issues have been resolved. This allows for better graft incorporation and a more stable knee.
Factors Influencing Success Rate
While revision ACL surgery can be successful, it is generally associated with lower success rates compared to primary ACL reconstruction. Several factors can affect the outcome of revision surgery, including:
- Cause of failure: The underlying cause of the initial ACL failure can impact the success of the revision.
- Number of previous surgeries: Patients who have undergone multiple ACL reconstructions have a lower chance of success.
- Graft choice: The type of graft used in the revision surgery can influence the outcome.
- Alignment: Correcting any malalignment issues is crucial for preventing graft failure.
- Associated injuries: Addressing any concomitant injuries, such as meniscus tears or cartilage damage, is essential for a successful outcome.
- Patient compliance: Adhering to the rehabilitation program is critical for restoring knee function and stability.
Rehabilitation (Recovery) After Revision ACL Surgery
Rehabilitation after revision ACL surgery is similar to that of primary ACL reconstruction. It typically involves a structured program of exercises and activities to restore range of motion, strength, and stability. The rehabilitation process may take several months, and patients must follow their surgeon’s and physical therapist’s instructions carefully to achieve the best possible outcome.
While each person’s recovery may differ, physical therapists typically conduct tests at 6 weeks, 12 weeks, 6 months, and 9 months after surgery to ensure proper recovery.
Factors that affect recovery time include:
- Type of revision reconstruction
- Use of a quadriceps tendon
- Condition of the original ACL graft
Immediately after surgery, managing pain and swelling is crucial. Patients are typically discharged with a knee brace and crutches. Crutches may be needed for 1-2 weeks. Pain is managed with medication, ice packs, and leg elevation. Physical therapy, which can begin a few days after the surgery once the pain and swelling go down, is also crucial to prevent scar tissue formation and reduce inflammation. Full activity is usually avoided for at least 9 months after surgery to ensure graft healing. The rehabilitation program for a revision ACL surgery may progress slower than for a primary ACL reconstruction.
Outcomes of ACL Revision Surgery
Outcomes after revision ACL reconstruction are generally inferior to primary ACL reconstruction. Excellent results can be achieved with regard to graft stability, return to play, and functional knee instability and depend largely on the operative procedure and the patient’s ability to recover.
Outcomes after revision ACL surgery can be evaluated through various measures, including knee laxity, patient-reported outcomes (PROs), and the presence of concomitant injuries.
Knee Laxity:
Revision ACL reconstruction has been shown to restore similar anterior-posterior knee laxity compared to primary ACL reconstruction.
Patient-Reported Outcomes (PROs):
- Inferior Outcomes Compared to Primary ACL Reconstruction: Meta-analyses show that patients undergoing ACL revision generally have inferior PROs compared to those undergoing primary ACL reconstruction. Specifically, patients who have had revision surgery reported inferior Lysholm Knee Scoring Scale scores.
- Improved PROs Compared to Pre-Op: Pooling current literature indicates improved PROs following ACL revision compared to what patients report preoperatively.
- Specific PRO Measures:
- At 2 years post-op, the Marx activity level and IKDC scores are significantly different between primary and revision ACL reconstruction groups, with superior results in the primary group.
- KOOS pain, sports/recreation, and QoL subscales are significantly lower in cases with ACL revision compared with primary ACL reconstruction.
- Factors Influencing PROs:
- Patients without a notch-plasty at the time of revision have an inferior outcome with regard to IKDC, KOOS-ADL and QoL subscales, WOMAC stiffness subscale, and ADL scores compared with baseline values.
- A new tibial tunnel at the time of revision is associated with inferior KOOS-ADL and WOMAC-ADL compared with using the previous bone tunnel.
- Returning to the preinjury level of activity is associated with higher Marx activity level, IKDC, and KOOS-QoL scores.
Concomitant Injuries:
- Patients undergoing ACL revision are observed to have fewer meniscal injuries compared with primary ACL reconstruction cases. For example, one study reported meniscal injuries in 33% of ACL revision cases compared to 42% in primary ACL reconstruction.
- Medial meniscus injuries are more common than lateral meniscus injuries in ACL revision.
- Concomitant injuries to a re-ruptured ACL have been associated with inferior outcomes after ACL revision. Previous lateral meniscus resection and severe trochlear cartilage injury have been shown to have the most detrimental effects on outcome.
Adverse Outcomes and Revision Rates:
- Approximately 3% of patients undergo further ipsilateral or contralateral ACL reconstruction within 5 years.
Graft Survival:
- The 5-year autograft survival after revision operation is around 80%.
What are the long-term activity levels for patients who undergo ACL revision surgery?
Long-term activity levels for patients who undergo ACL revision surgery tend to be lower compared to both their pre-injury activity levels and the activity levels of individuals who have not had ACL surgery.
Reduced Physical Activity:
- Individuals who underwent ACL reconstruction (ACLR) engaged in significantly less weekly moderate-to-vigorous physical activity (MVPA), daily MVPA, and had a lower number of daily steps compared to healthy matched controls.
- Long-term after ACLR, participants undergoing ACL surgery were less physically active compared with their non-injured peers and did not satisfy recommendations regarding steps per day.
- The ACLR group spent less time in weekly MVPA (mean = -55.86 min) and in daily MVPA (mean = -15.59 min), and they had fewer daily steps (mean = -1724.39 steps) relative to their non-injured counterparts.
- Individuals with a history of ACLR participated in approximately 316.8 minutes per week in MVPA, 67 minutes in daily MVPA, and took 8337 steps per day.
Factors Affecting Activity Levels:
- High baseline activity level was associated with higher activity at 2 years, while lower baseline BMI was also a factor.
- Factors associated with lower activity include female gender, smoking within 6 months, and revision ACLR.
Return to Sport:
- It usually takes 9 to 12 months for a patient to return to participating in sports after an ACL reconstruction, depending on the level of participation.
- The determination of when a patient has fully recovered is based on the restoration of muscle strength, range of motion, and proprioception of the knee joint.
- Activity level in athletes or patients is one of the primary outcomes for ACLR and is believed to be associated with future risk of failure and premature arthritis.
Importance of Rehabilitation:
- Specific exercise programs are necessary to improve the health of individuals who have undergone ACLR, given that ACLR negatively affects their physical activity variables1.
- It is critical that the patient have a rehabilitation period that is carefully supervised by an appropriate physical therapist, as well as follow-up appointments with the surgeon.
How can I optimize my physical therapy routine after revision ACL surgery?
To optimize your physical therapy routine after revision ACL surgery, consider these key strategies:
- Adhere to a Structured Program: Follow a structured rehabilitation program with exercises and activities to restore range of motion, strength, and stability. The rehabilitation process may take several months, and consistency is key.
- Early Goals: Aim for full extension and 70 degrees of flexion by the end of the first week. Early knee extension establishes the foundations for the entire rehabilitation program.
- Manage Pain and Swelling: Control pain and swelling immediately after surgery to facilitate early physical therapy. Elevate your leg with your knee above your heart for the first 3-5 days after surgery.
- Focus on Early Motion and Strengthening: Physical therapy should begin a few days after surgery to prevent scar tissue formation and reduce inflammation. Focus on increasing range of motion, decreasing knee effusion, and quadriceps activation exercises early on.
- Incorporate Home-Based Rehabilitation: Supplement supervised physical therapy sessions with effective home-based exercises to achieve range of motion and strength goals.
- Progressive Training: After the initial phase, later-stage rehabilitation should incorporate sport-specific exercises to restore high-level knee function.
- Address Neuromuscular Control: Effective physical therapy should aim to reduce reinjury by addressing modifiable factors, such as neuromuscular control of the lower extremity.
- Prehabilitation: If a revision is planned, consider prehabilitation to improve strength and range of motion before the surgery.
- Regular Evaluation and Adjustment: At each visit, your physical therapist or athletic trainer should evaluate your strength, range of motion, and swelling, advancing your therapy and sporting activities based on your progress.
- Follow-up: Continue physical therapy as you return to your pre-operative, fully competitive level of activity.
- Consider Indicators: Monitor pain, swelling, muscular contracture, range of motion limitations, and abnormal gait patterns to assess progress and adjust the rehabilitation program accordingly.
Conclusion
Revision ACL surgery is a complex procedure that requires careful planning, expert surgical skill, and dedicated rehabilitation. While success rates are lower compared to primary ACL reconstruction, advancements in surgical techniques, imaging, and personalized approaches continue to improve outcomes. Patients considering revision ACL surgery should consult with experienced orthopedic surgeons to discuss their specific case, understand the potential risks and benefits, and develop a comprehensive treatment plan.
By adhering to best practices in surgical technique, graft selection, and rehabilitation, healthcare providers can optimize the chances of successful outcomes for patients undergoing revision ACL surgery. As research in this field progresses, we can expect further improvements in the management of complex ACL injuries, ultimately leading to better long-term outcomes for patients.
