Age, male sex, higher posterior tibial slope, deep sulcus sign, bone bruises on the lateral femoral condyle, and concomitant medial meniscal tears are risk factors for lateral meniscal posterior root tears: a systematic review and meta-analysis

PURPOSE

Lateral meniscus posterior root tears (LMPRTs) are commonly found in patients with anterior cruciate ligament (ACL) injuries. However, risk factors for LMPRTs are not well known. This study was designed to systematically review the available evidence regarding risk factors associated with LMPRTs.

METHODS

The PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched for papers containing the key words "lateral meniscus posterior root tears", "LMPRTs" and "risk factor". Inclusion screening, data extraction, and quality assessment of the included articles were conducted independently by two authors. Statistical analysis was conducted to determine risk factors for LMPRTs.

RESULT

Seventeen studies with a total sample size of 6, 589 patients were identified. The pooled prevalence of LMPRTs was 9.6% (range, 5.1-33.8%) for ACL injury. Significant risk factors included a patient age of < 30 [OR = 1.4, 95% CI (1.07, 1.84), p = 0.01], male sex [OR = 1.50, 95% CI (1.24,1.81), p = 0.01], higher body mass index (BMI) [MD = 0.45, 95% CI (0.13, 0.76), p < 0.01], higher lateral posterior tibial slope (LPTS) [MD = 2.22, 95% CI (1.37, 3.07), p < 0.01], deep sulcus sign [OR = 5.76, 95% CI (1.35, 24.52), p < 0.01] and bone bruises on lateral femoral condyle [OR = 4.88, 95% CI (1.27, 18.77), p < 0.01], lateral meniscal extrusion > 1 mm [OR = 5.56, 95% CI (1.52, 20.29), p < 0.01] and > 3 mm [OR = 12.91 95% CI (1.28, 130.01), p < 0.01], medial meniscal tears [OR = 1.40, 95% CI (1.12, 1.75), p < 0.01], and medial ramp lesions [OR = 2.29, 95% CI (1.35, 3.89), p < 0.01].

CONCLUSION

Age below 30, male, higher BMI, higher LPTS, deep sulcus sign, bone bruises on lateral femoral condyle, lateral meniscal extrusion, medial meniscal tear, and medial ramp lesion are risk factors for LMPRTs.

LEVEL OF EVIDENCE

Level IV.

Steep posterior lateral tibial slope, bone contusion on lateral compartments and combined medial collateral ligament injury are associated with the increased risk of lateral meniscal tear

PURPOSE

To determine the risk factors for lateral meniscus and root tears in patients with acute anterior cruciate ligament (ACL) injuries.

METHODS

A total of 226 patients undergoing acute ACL reconstruction were included in the study sample. Exclusion criteria were revisions, fractures, chronic cases, and multiple ligament injuries, with the exception of medial collateral ligament (MCL) injuries. The patients were divided into groups based on the presence of lateral meniscus and root tears by arthroscopy. Binary logistic regression was used to analyze risk factors including age, sex, body mass index (BMI), injury mechanism (contact/non-contact), Segond fracture, side-to-side laxity, location of bone contusion, medial and lateral tibial and meniscal slope, mechanical axis angle, and grade of pivot shift.

RESULTS

Overall lateral meniscus (LM) tears were identified in 97 patients (42.9%), and LM root tears were found in 22 patients (9.7%). The risk of an LM tear in ACL-injured knees increased with bone contusion on LTP (odds ratio [OR], 3.5; 95% confidence interval [CI] 1.419-8.634; P = 0.007), steeper lateral tibial slope (OR, 1.133; 95% CI 1.003-1.28; P = 0.045), MCL injury (OR, 2.618; 95% CI 1.444-4.746; P = 0.002), and non-contact injury mechanism (OR, 3.132; 95% CI 1.446-6.785; P = 0.004) in logistic regression analysis. The risk of LM root tear in ACL-injured knees increased with high-grade pivot shift (OR, 9.127; 95% CI 2.821-29.525; P = 0.000) and steeper lateral tibial slope (OR, 1.293; 95% CI 1.061-1.576; P = 0.011).

CONCLUSION

The increased risk of LM lesions in acute ACL-injured knees should be considered if significant risk factors including bone contusion on lateral compartments, MCL injury, and a steeper lateral tibial slope are present. Moreover, high-grade rotational injury with steeper lateral tibial slope are also significant risk factors for LM root tears, and therefore care should be taken by clinicians not to miss such lesions.

LEVEL OF EVIDENCE

III.

Repair of the lateral posterior meniscal root improves stability in an ACL-deficient knee

PURPOSE

To investigate the stabilizing effect of a lateral meniscus posterior root repair in an ACL and root deficient knee.

METHODS

The hypothesis of the current study was that a sequential transection of the posterior root and the meniscofemoral ligaments in an ACL-deficient knee increases rotational instability, and conversely, a repair of the meniscus root reduces the internal tibial rotation. Therefore, eight human knee joints were tested in a robotic setup (5 N m internal torque, 50 N m anterior translation load). Five conditions were tested: intact, ACL cut, ACL cut + lateral meniscus posterior root tear (LMRT), ACL cut + LMRT + transection of the MFL and ACL cut + lateral meniscus root repair. The angles of internal tibial rotation as well as anterior tibial translation were recorded.

RESULTS

Transection of the lateral meniscus posterior root increased the internal tibial instability as compared to the ACL-insufficient state. A significant increase was detected in 60° and 90° of flextion. Sectioning of the meniscofemoral ligament further destabilized the knees significantly at all flexion angles as compared to the ACL-deficient state. Even in 30°, 60° and 90° a significant difference was detected as compared to the isolated root tear. A tibial fixation of the lateral meniscus root reduced the internal tibial rotation in all flexion angles and led to a significant decrease of internal tibial rotation in 30° and 90° as compared to the transection of the root and the MFL. The anterior tibial translation was increased in all conditions as compared to the native state.

CONCLUSION

A lateral meniscus root repair can reduce internal tibial rotation in the ACL-deficient knee. To check the condition of the lateral posterior meniscus root attachment is clinical relevant as a lateral meniscus root repair might improve rotational stability.