An injury to the knee where ACL and meniscus tears occur are a somewhat common occurrence. Because the ACL and meniscus are knee stabilizers that work together, an injury that tears or injures one can injure the other. This is typical in traumatic knee injuries, especially injuries that occurred with a sudden twisting motions or direct impacts.

A December 2024 study (3) reported on a new “terrible triad” – anterior cruciate ligament (ACL) tear with a concomitant medial meniscus ramp tear and lateral meniscus root tear. In this study patient-reported outcomes (PROs) for isolated ACL reconstruction (ACLR) versus an ACLR with concomitant medial meniscus ramp and lateral meniscus root repairs were compared. Both groups had 41 patients followed.

What the researchers found was that patients who had isolated ACL repair and those who had ACLR with concomitant medial meniscus ramp and lateral meniscus root repairs had similar outcomes at two-year follow-up. The researchers concluded: “Given the optimistic short-term outcomes for isolated versus triad ACLR patients and the known biomechanical consequences of these untreated meniscal injuries, medial meniscus ramp and lateral meniscus root repairs should be performed when encountered concurrently with an ACL tear when possible.”

A January 2025 study (1) examined the Anterior cruciate ligament (ACL) injury and medial meniscal extrusion, implicated in post-traumatic osteoarthritis progression. The researchers hypothesized that medial meniscal extrusion (the meniscus has moved out of place towards the inner knee) would increase longitudinally (across the length of the meniscus) after ACL injury and ACL reconstruction, with greater changes in the injured knee compared with the other  knee, leading to cartilage degeneration.

The study aimed to assess medial meniscal extrusion three years after ACL reconstruction.

  • A total of 54 participants with unilateral ACL injuries underwent preoperative bilateral knee MRI.
  • A total of 36 participants completed MR scans at 6 months and 3 years after ACLR.
  • Medial meniscal extrusion and relative percentage of extrusion obtained pre- and postoperatively after ACLR on the ipsilateral side were significantly greater than those on the contralateral side, and the longitudinal increases on the ipsilateral side were greater than those on the contralateral side. Postoperative relative percentage of extrusion was significantly associated with cartilage degeneration in the posterior medial femoral condyle.

A December 2024 study (2) evaluated the healing of meniscal repair performed concomitantly with anterior cruciate ligament reconstruction (ACLR) using second-look arthroscopy, and the relationship between meniscal healing and knee laxity.

  • Of 562 anterior cruciate ligament reconstructions, 113 knees with 137 meniscal repairs were analyzed.
  • Second-look arthroscopy classified 114 (83.2%) menisci as healed and 23 (16.8%) as failed.

The researchers concluded: “Patients with failure of meniscal repair performed concomitant to ACLR demonstrated significantly greater rotational knee laxity at the time of second-look arthroscopy.”

A June 2022 study (4) found “Meniscus injuries occurred 77% of the time in (the) study sample when there was a persistent ACL injury. In comparison to a lateral meniscus injury (outer knee meniscus damage), the incidence of medial meniscus injury associated with chronic ACL tear was higher. In comparison to the anterior horn and body of the medial meniscus, the majority of medial meniscus tears were found in the posterior horn (at the back of the knee).

A May 2025 study (5) entered the debate on pediatric knee surgery in the adolescent athlete. In this study fifty skeletally immature patients who underwent ACL reconstruction were followed. Of these patients, 21 had meniscal injury in addition to the ACL tear and 29 did not.

Results: Out of 50 patients with a mean age of 13.2 years, the meniscal injury group had 67% return-to-sport (12/18), and the isolated ACLR group had 75% return-to-sport (18/24) after 24 months suggesting no differences in return-to-sport 24 months after ACL reconstruction with or without meniscal injury. Further, 71% of the group after ACL reconstruction—with or without meniscal repair—returned to their original level of sports activity, and return-to-sports did not depend on the presence or absence of additional meniscal injuries. The failure rate of meniscal repair was 19% in this group.

References

1 Watanabe S, Joseph GB, Sato D, Lansdown DA, Brandao Guimaraes J, Link TM, Ma CB. Longitudinal Changes in Medial Meniscal Extrusion After ACL Injury and Reconstruction and Its Relationship With Cartilage Degeneration Assessed Using MRI-Based T1ρ and T2 Analysis. Am J Sports Med. 2025 Jan 2:3635465241305734. doi: 10.1177/03635465241305734. Epub ahead of print. PMID: 39743985.
2 Hanaki S, Fukushima H, Abe K, Ota K, Kobayashi M, Kawanishi Y, Kato J, Yoshida M, Takenaga T, Murakami H, Nozaki M. Greater Rotational Knee Laxity Observed at Second-Look Arthroscopy in Patients with Failed Meniscal Repair Performed at the Time of Anterior Cruciate Ligament Reconstruction. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2024 Dec 24.
3 Shoemaker EP, Tollefson LV, Kennedy NI, McGaver RS, Homan M, Sieffert KJ, Shah AD, Wulf CA, Larson CM, Bjerke BP, LaPrade RF. Comparing Postoperative Outcomes of Isolated Anterior Cruciate Ligament Reconstruction and the “Terrible Triad” Anterior Cruciate Ligament Reconstruction With Medial Meniscus Ramp and Lateral Meniscus Root Repairs. Orthopaedic Journal of Sports Medicine. 2024 Dec;12(12):23259671241303178.
4 Venkataraman S, Ethiraj P, Shanthappa AH, Vellingiri K. Association of meniscus injuries in patients with anterior cruciate ligament injuries. Cureus. 2022 Jun 12;14(6).
5 Lehoczky G, Flumian C, de Gauzy JS, Accadbled F. Similar Return-to-Sports After Anterior Cruciate Ligament Reconstruction With or Without Meniscal Repair in Skeletally Immature Patients: A Prospective, Comparative Cohort Study. Journal of Pediatric Orthopaedics. 2025 May 1;45(5):e473-9.