Saudi Journal of Sports Medicine

: 2015  |  Volume : 15  |  Issue : 1  |  Page : 94--96

Lateral meniscus root avulsion with anterior cruciate ligament tear: A case report and surgical technique

Abdulaziz Z Alomar 
 Department of Orthopaedic Surgery, King Saud University, Medical College, Riyadh, Saudi Arabia

Correspondence Address:
Abdulaziz Z Alomar
Department of Orthopaedic Surgery, King Khalid University Hospital, Medical College, King Saud University, Riyadh
Saudi Arabia


Lateral meniscus root (LMR) injuries associated with anterior cruciate ligament (ACL) tears are less frequent than medial meniscus root (MMR) injuries. Among the reported cases of lateral meniscus injuries associated with an ACL tear, those involving the posterior horn are most frequent, followed by LMR tear; however, LMR avulsion is a very rare condition, and its incidence is still unknown. Injuries that involve detachment of the meniscus root attachments profoundly affect the meniscal biomechanics and kinematics and can accelerate degenerative changes within the knee joint. Thus, it is imperative to accurately and concisely identify such lesions to guide treatment and surgical decision-making and help determine prognosis. We report a rare case of a male athlete with an LMR avulsion associated with an ACL tear; this condition was surgically treated with ACL reconstruction and in situ pull-out suture repair.

How to cite this article:
Alomar AZ. Lateral meniscus root avulsion with anterior cruciate ligament tear: A case report and surgical technique.Saudi J Sports Med 2015;15:94-96

How to cite this URL:
Alomar AZ. Lateral meniscus root avulsion with anterior cruciate ligament tear: A case report and surgical technique. Saudi J Sports Med [serial online] 2015 [cited 2020 Jun 6 ];15:94-96
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Lateral meniscus tears can occur in the anterior horn, body, posterior horn, or root of the meniscus. The lateral meniscus root (LMR) is approximately two times more mobile than the medial meniscus root (MMR), which has led to the hypothesis that the lateral meniscus is less involved with knee stabilization and consequently encounters less stress than that encountered by the medial meniscus. [1],[2],[3] Therefore, the lateral posterior horn is less affected by chronic anterior cruciate ligament (ACL) instability than the medial posterior horn. [2],[4]

Concomitant tearing of the lateral meniscus is associated with approximately 20% of ACL tear injuries, with 70-87% of them involving the posterior horn. [5] An incidence rate of < 1% has been reported for LMR tears without a concomitant ACL tear. [6]

While MMR avulsion and LMR tears have been reported, very limited data are available on LMR avulsions. By disrupting the hoop forces, root tears can potentially have a detrimental effect on the lateral compartment biomechanics. [7] However, the mechanism, incidence, natural history, and associated injuries of lateral root tears are still unknown.

The incidence of LMR tears associated with ACL tears was reported to be 9.8-12.4%; [7],[8] however, the incidence of LMR avulsions without a tear is still unknown.

Additionally, the risk factors for lateral meniscal posterior root tears are relatively unknown. Sports activity is involved in approximately 87% of lateral meniscal injuries, and Beldame et al., reported that 70% of such injuries occurred in pivot-contact sports. [2],[9]

We report a rare case of a male athlete with an LMR avulsion associated with an ACL tear; this condition was surgically treated with ACL reconstruction and transosseous in situ pull-out suture repair.


A 21-year-old male athlete had a twisting injury to his right knee during a soccer game. He had immediate onset of pain and effusion, which prevented him from finishing the game. The patient was unable to participate in any competition for 4 weeks after the injury because of significant history of recurrent knee instability and pain. Four weeks after injury, physical examination revealed mild effusion with positive Lachman's and pivot-shift tests. He had mild tenderness to palpation over his lateral joint line, mainly over the postero-lateral joint area. Deep squatting reproduced the deep postero-lateral knee pain. There was no tenderness to palpation over the medial joint line. The other results of knee examination were normal, with no increased joint line opening to varus or valgus stress at 30° of knee flexion. He had a negative posterior drawer and full range of motion. Before the injury, he played high-level competitive soccer on club teams and had no previous history of injury to his right knee.

Plain radiographs showed normal findings. Magnetic resonance imaging (MRI) was not performed, because the physical findings were sufficient to diagnose a torn ACL with high suspicion of a lateral meniscus injury. Because of the significant instability and inability to return to sports, surgical ACL reconstruction with or without a lateral meniscus repair was preferred.

Under arthroscopic examination, in addition to a complete ACL tear, it was noted that the root attachment of the lateral meniscus had avulsed off its tibial attachment with no tear [Figure 1]. The entire posterior horn of the lateral meniscus was also detached and unstable. The normal meniscal root attachment site was identified at the tibia. The avulsed root was found to be amenable for fixation, with a good chance of reducing the posterior horn root attachment to its normal anatomic position.{Figure 1}

ACL reconstruction was performed first. After drilling the femoral and tibial ACL tunnels and before passing the graft, were paired the root avulsion. We trephinated the posterior joint capsule around the meniscal attachment and synovium with a shaver, and we employed a rasp to stimulate healing of the perisynovial tissue. A transosseous pull-out suture technique was used to repair the root avulsion. Non absorbable sutures were secured using a suture passer through the LMR. Then, an eyelet pin was drilled from the center of the root attachment site through the anteromedial tibial surface using an ACL guide. Finally, the sutures were pulled through the tibia using the eyelet pin. The ACL graft was passed through the tibial tunnel and was fixed. Finally, the meniscus root sutures were tied over a metal staple that was used to fix the ACL graft at the tibial side [Figure 2].{Figure 2}

Postoperatively, the patient followed a post-ACL reconstruction and meniscus repair rehabilitation program. At one-year follow-up, he reported no more instability or pain on his knee. At nine-months after surgery He was able to return to the high-level competitive soccer with no limitation.


Proper diagnosis of a meniscal root injury is critical for appropriate patient counseling and treatment decision-making. Unfortunately, clinical diagnosis of this injury is challenging because of the low likelihood that the common signs and symptoms associated with meniscal body injuries will manifest in patients with root tears.

For the menisci to function properly, the biomechanical integrity of each meniscus root on the tibial plateau must be maintained. [1],[10] Avulsions of the posterior root attachment of the lateral meniscus and radial tears adjacent to the root attachment can result in significantly decreased tibio-femoral contact areas and increased mean and peak contact pressures in the lateral compartment of the knee. [1],[5],[11]

In the absence of a highly sensitive and specific history and physical examination findings, MRI is increasingly used to diagnose meniscal root tears. However, obtaining an accurate diagnosis with MRI is often dependent on the quality of the imaging and the radiologist's skill. Typically, LMRs are best seen on coronal and sagittal sequences that depict the posterior slope and apex of the lateral tibial eminence. [6] To date, the sensitivity and specificity for the detection of lateral root tears by MRI are unknown.

Surgical repair of posterior root tears of the lateral meniscus remains controversial. Some authors have reported a high degree of symptomatic improvement in posterior LMR tears treated with repair at the time of concomitant ACL reconstruction, whereas others have deemed repair as unnecessary. [10],[12] In situ pull-out suture repair of these tears significantly improves the loading profiles of the lateral compartment, which may help prevent the development of articular cartilage degeneration that has been reported to be associated with partial meniscectomy. [5]


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