ACL and Meniscus Tear Combined Injury

When someone tears their ACL, there’s roughly a 50 to 60 percent chance they’ve also torn their meniscus. At Ochsner-Andrews Sports Medicine Institute in Baton Rouge, Louisiana, Dr. Burnham sees this combination regularly, and it changes everything about how the surgery is approached, rehabilitation, and long-term outcomes. The ACL tear itself is significant, but add a meniscus injury to the picture, and you’re dealing with two structures that work together to keep your knee stable and functional. Understanding how these injuries interact is critical for anyone making treatment decisions.

A meniscus tear combined with an ACL tear isn’t simply two separate problems happening at the same time. The mechanism that tears the ACL, the abnormal motion and rotational forces, frequently damages the meniscus tissue as well. And once the meniscus is torn, it can’t heal itself the way soft tissue usually does. That’s why the approach to surgery, the rehabilitation plan, and the timeline for return to sport all shift when the clinical team is dealing with combined injuries. This article walks through what happens when both structures are damaged, why it matters, and what realistic expectations look like.

Why ACL and Meniscus Tears Happen Together

The ACL sits at the center of the knee’s stability system. When the ACL tears, usually from a sudden deceleration or a pivoting motion, the knee loses its primary restraint against forward translation of the tibia. But the damage doesn’t stop there. As the tibia shifts forward and rotates excessively on the femur, the meniscus, which sits like a shock-absorbing wedge between the bones, can get caught and torn in the process.

The pattern of meniscus injury depends on whether the ACL tear is acute or chronic. With an acute ACL tear, clinicians tend to see lateral meniscus tears more often, because of the rotational forces at play. If someone has had a chronically unstable knee from an unrepaired ACL tear, the meniscus can degenerate or tear over time, and medial meniscus tears become more common.

Research from Dr. Burnham’s group has shown how powerful this interaction really is. In a study examining rotatory knee laxity, the investigators found that patients with combined ACL and lateral meniscus tears had significantly higher rotatory laxity than those with isolated ACL tears. The correlation between tibial acceleration and translation was 0.53 in combined injuries, compared to 0.32 in isolated ACL tears. And in male patients with both injuries, that correlation jumped to 0.75, suggesting the meniscus tear compounds rotatory instability in a major way.¹

Types of Meniscus Tears Found with ACL Injuries

Not all meniscus tears are the same, and the type of tear you have matters for how it’s repaired or managed. When evaluating a patient with an acute ACL injury, Dr. Burnham looks for several specific tear patterns that are common in this scenario.

Ramp lesions are posterior meniscocapsular tears that occur on the inner edge of the meniscus, where it attaches to the knee joint capsule. For years, these were underdiagnosed because they don’t show up clearly on standard MRI. But research from Dr. Burnham’s group has improved the understanding of detecting ramp lesions on imaging. The study found sensitivity ranging from 54 to 85 percent and specificity from 92 to 99 percent, depending on the reviewer.² Ramp lesions can be subtle, but they matter because they affect knee stability, and they’re repairable if identified.

Lateral meniscus tears come in several patterns: bucket handle tears (where a piece of the meniscus flips into the center of the joint), radial tears (which split the meniscus from its inner edge outward), and root tears (where the meniscus detaches from its anchoring point). Each requires a different repair strategy.

Medial meniscus tears are more common when there’s chronic ACL deficiency, meaning the knee has been unstable for a while. These can range from small peripheral tears to larger degenerative tears.

One consistent finding in research is the lateral femoral notch sign. The femur has a small notch where the ACL attaches. In patients who tear their ACL, this notch is sometimes deeper than normal. Interestingly, greater notch depth is associated with lateral meniscus injury. In a study by Kanakamedala, Burnham, and colleagues, patients with lateral meniscus tears had significantly greater lateral femoral notch depths than those without (1.0 vs. 0.6 millimeters on radiographs), which was statistically significant.³ This indicates that anatomy plays a role in who gets these combined injuries.

Surgical Approach: Repair, Preserve, or Remove

The guiding principle Dr. Burnham follows is simple: preserve meniscus tissue whenever possible. The meniscus doesn’t regenerate. Once it’s removed through a partial meniscectomy, it doesn’t grow back. That tissue loss accelerates cartilage wear and increases the risk of arthritis down the line. So unless the tear is completely irreparable, the repair is performed.

During ACL reconstruction, the meniscus is carefully evaluated for tears and repairability. If a tear is present and repairable, both procedures are performed in the same surgery. The evidence supports this approach. A systematic review found that patients undergoing all-inside meniscal repair combined with ACL reconstruction had a 90 percent return-to-sport rate.⁴ That’s an encouraging outcome that justifies the extra time and technical precision required for the repair.

Some meniscus tears, particularly root tears, are especially critical to identify and repair. Root tears happen where the meniscus is anchored to the tibia bone. If not repaired, the meniscus loses its structural function and can degenerate rapidly. A systematic review examining lateral meniscus posterior root repair during ACL reconstruction found significant improvements in functional scores (Lysholm scores improved from 58 to 91, and IKDC scores from 61 to 87), with a healing rate exceeding 93 percent on second-look arthroscopy.⁵

If the meniscus is completely irreparable, and the patient is young and active, Dr. Burnham considers meniscus transplantation. This involves transplanting allograft meniscus tissue from a donor. A systematic review of combined meniscus allotransplantation and ACL reconstruction showed good clinical outcomes over 2 to 14 years of follow-up, with improvements above the minimal clinically important difference for Lysholm and Tegner activity scores.⁶ It’s a more involved procedure than simple repair, but for the right patient, it’s worth it.

The decision between repair, transplant, or partial removal hinges on the tear location, tear pattern, tissue quality, and the patient’s age and activity level. This is where individual judgment matters. Dr. Burnham discusses these options transparently with each patient so they understand what preservation looks like versus what loss of meniscus tissue means for their long-term knee health.

How Combined Injuries Affect Recovery

The rehabilitation path diverges depending on whether the meniscus is being repaired or an isolated ACL tear is being managed. With ACL reconstruction alone, patients typically begin weight bearing as tolerated right away and can progress to aggressive early range-of-motion work within the first few weeks. The goal is to restore motion and strength quickly while the graft heals and integrates.

When the meniscus has also been repaired, the team needs to be more cautious in the early stages. The meniscus repair needs time to heal without being disrupted by aggressive motion or load. Typically, Dr. Burnham recommends protected weight bearing for the first 4 to 6 weeks, with limited knee flexion to protect the repair. This means using crutches longer, avoiding deep squats, and being more deliberate in the early range-of-motion exercises. It feels slower at first, but it protects the repair and sets up better long-term outcomes.

The total rehabilitation timeline is typically 1 to 2 months longer when a meniscus repair is involved. Instead of returning to sport in 6 to 9 months, a combined injury might take 8 to 11 months. But this extended timeline is an investment in saving tissue and protecting your knee long-term. The early patience pays dividends later. Detailed knee rehabilitation protocols outline the phase-by-phase progression for combined procedures.

Return to sport is still criteria-based, not calendar-based. Dr. Burnham does not clear a patient to play just because they’ve reached some magic number of weeks. The team assesses strength symmetry, range of motion, proprioception, and sport-specific agility through a comprehensive functional progression process. For combined injuries, meeting these criteria sometimes takes longer, but the process is the same. The goal is objective evidence that the knee is ready for the demands of competition.

The Long-Term Picture: Protecting Your Knee from Arthritis

This is where meniscus preservation becomes more than just a technical preference. It becomes a stand for your future quality of life. The meniscus is the knee’s shock absorber. It distributes load evenly across the joint surface. When meniscus tissue is lost, that load distribution becomes uneven, and the cartilage underneath bears more stress.

ACL reconstruction alone reduces the risk of early-onset arthritis compared to leaving the knee untreated, but it doesn’t eliminate that risk. Adding meniscus preservation to the equation further protects the joint. When the meniscus can be saved through repair, long-term joint health is significantly improved. The likelihood of developing arthritis in your 40s or 50s is substantially reduced.

This is why Dr. Burnham sometimes spends extra time in the operating room to repair a meniscus that could technically be partially removed. The meniscectomy would be faster, but the repair preserves your joint. And from a clinical perspective, that’s the right call for someone who wants to stay active for decades to come.

The Role of the Anterolateral Complex

When ACL and meniscus injuries occur together, particularly with lateral meniscus tears, rotatory instability may be more pronounced than with the ACL tear alone. This brings us to the anterolateral complex, or ALC, a group of structures on the outside of the knee that contribute to rotational stability.

The ALC includes the iliotibial band, the anterolateral ligament (ALL), and the capsule. In some patients with combined injuries and significant rotatory laxity, Dr. Burnham may add an anterolateral reconstruction or augmentation to the ACL reconstruction. This is an individualized decision based on physical examination findings, imaging, and whether the patient has risk factors for rotatory instability, like greater femoral notch depth or female sex.⁷

The goal of ALC augmentation is to provide additional rotational control and reduce the burden on the ACL reconstruction alone. For certain patients, this additional procedure significantly improves long-term stability and return-to-sport outcomes. But it’s not routine. Dr. Burnham assesses each knee individually and makes the recommendation based on what that specific knee needs.

The Bottom Line

ACL and meniscus injuries frequently occur together, and this combination requires a more nuanced surgical and rehabilitation approach. The decision to repair versus remove meniscus tissue is one of the most important choices you’ll make for your long-term knee health. Preservation should be the priority whenever the tear is repairable.

Yes, combined injury repair takes more time. Yes, the rehabilitation timeline is longer. But you’re investing in a knee that will remain more stable and more resistant to arthritis as you age. If you’ve sustained an ACL tear with meniscus involvement, having a detailed conversation with your surgeon about meniscus preservation options is worth having. The work you do in the operating room and in rehabilitation now directly shapes how well your knee functions in 10, 20, or 30 years. To schedule a consultation, contact our office or learn more about Dr. Burnham’s approach.

References

1. Musahl V, Burnham J, Lian J, Popchak A, Svantesson E, Kuroda R, Zaffagnini S, Samuelsson K. High-grade rotatory knee laxity may be predictable in ACL injuries. Knee Surg Sports Traumatol Arthrosc. 2018;26(12):3762-3769. PMID: 29931484 | DOI: 10.1007/s00167-018-5019-y

2. Arner JW, Herbst E, Burnham JM, Soni A, Naendrup JH, Popchak A, Fu FH, Musahl V. MRI can accurately detect meniscal ramp lesions of the knee. Knee Surg Sports Traumatol Arthrosc. 2017;25(12):3955-3960. PMID: 28343325 | DOI: 10.1007/s00167-017-4523-9

3. Kanakamedala AC, Burnham JM, Pfeiffer TR, Herbst E, Kowalczuk M, Popchak A, Irrgang J, Fu FH, Musahl V. Lateral femoral notch depth is not associated with increased rotatory instability in ACL-injured knees: a quantitative pivot shift analysis. Knee Surg Sports Traumatol Arthrosc. 2018;26(5):1399-1405. PMID: 29119285 | DOI: 10.1007/s00167-017-4770-9

4. Totlis T, Haunschild ED, Otountzidis N, Stamou K, Condron NB, Tsikopoulos K, Cole BJ. Return-to-Sport Rate and Activity Level Are High Following Arthroscopic All-Inside Meniscal Repair With and Without Concomitant Anterior Cruciate Ligament Reconstruction: A Systematic Review. Arthroscopy. 2021;37(7):2351-2360. PMID: 33753131 | DOI: 10.1016/j.arthro.2021.02.046

5. Zheng T, Song G, Li Y, Zhang Z, Ni Q, Cao Y, Feng Z, Zhang H, Feng H. Clinical, Radiographic, and Arthroscopic Outcomes of Surgical Repair for Radial and Avulsed Lesions on the Lateral Meniscus Posterior Root During ACL Reconstruction: A Systematic Review. Orthop J Sports Med. 2021;9(3):2325967121989678. PMID: 33796590 | DOI: 10.1177/2325967121989678

6. Tan KSA, Chua SKK, Yeo EYH, Bin Abd Razak HR. Combined Meniscal Allograft Transplantation and Anterior Cruciate Ligament Reconstruction Show Good 2- to 14-Year Outcomes: A Systematic Review. Arthroscopy. 2023;39(6):1584-1592.e1. PMID: 36343764 | DOI: 10.1016/j.arthro.2022.10.042

7. Musahl V, Getgood A, Neyret P, Claes S, Burnham JM, Batailler C, Sonnery-Cottet B, Williams A, Amis A, Zaffagnini S, Karlsson J. Contributions of the anterolateral complex and the anterolateral ligament to rotatory knee stability in the setting of ACL Injury: a roundtable discussion. Knee Surg Sports Traumatol Arthrosc. 2017;25(4):997-1008. PMID: 28286916 | DOI: 10.1007/s00167-017-4436-7