Concomitant Lateral Meniscal Tears in Pediatric and Adolescent Patients Undergoing Combined Medial Meniscal Ramp Lesion Repair and Anterior Cruciate Ligament Reconstruction Are Frequently Missed on MRI, Are Often Vertical or Root Tears, and Are Usually Repaired: A Multicenter Study

Abstract

Background:

In pediatric and adolescent patients with medial meniscal ramp lesions (MMRLs) undergoing anterior cruciate ligament reconstruction (ACLR), the presence of concomitant lateral meniscal tears (LMTs) are not well-characterized.

Purpose:

To describe the characteristics and surgical management of concomitant LMTs in pediatric and adolescent patients undergoing MMRL repair during primary ACLR.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients <18 years old who underwent an MMRL repair during primary ACLR at 5 institutions from 2013 to 2025 were included. All MMRLs were diagnosed arthroscopically and defined as a partial or complete peripheral vertical/longitudinal tear of the posterior horn of the medial meniscus at or ≤3 mm from the meniscocapsular junction. The presence, location, and surgical management of arthroscopically identified concomitant LMTs were gathered from the operative reports. Lateral meniscus root tears (LMRTs) were categorized using the LaPrade classification. Patients with and without concomitant LMT at the time of MMRL repair during primary ACLR were compared.

Results:

In total, 189 pediatric and adolescent patients underwent an MMRL repair during primary ACLR at a mean age of 16.1 ± 1.4 years (range, 12.0-17.9 years). Concomitant LMTs were arthroscopically diagnosed in 122 (65%) patients, of which 38 (31%) were missed on the initial preoperative magnetic resonance imaging (MRI) report. Surgically, the majority of concomitant LMTs (67%) were treated with repair while 27% were treated with partial meniscectomy or observation (6%). LMTs were most frequently localized to the posterior horn (61%) or posterior root (27%). The most common LMT morphology was vertical/longitudinal (41%), followed by LMRTs (25%), complex nonroot tears (15%), radial tears (12%), and bucket-handle tears (4%). Of the 31 LMRTs identified, type 4 complex oblique root tears were most prevalent (65%), followed by type 2 complete radial root tears (26%), type 1 partial stable root tears (6%), and a type 5 bony root avulsion (3%). Significant risk factors associated with the presence of a concomitant LMT included male sex (odds ratio [OR], 1.9; 95% CI, 1.0-3.7; P = .044) and obesity (OR, 2.5; 95% CI, 1.0-6.1; P = .046).

Conclusion:

In this multicenter study, 65% of pediatric and adolescent patients undergoing MMRL repair during primary ACLR had a concomitant LMT and the majority were localized to the posterior horn and posterior root. As 31% of concomitant LMTs were missed on preoperative MRI, the posterior aspect of the lateral meniscus should be carefully evaluated at the time of surgery in pediatric patients with MMRLs. Nearly half of the concomitant LMTs identified in this cohort were LMRTs, complex tears, complete radial tears, or bucket-handle tears. Overall, surgeons should anticipate performing an additional lateral meniscal repair in nearly half of pediatric patients undergoing an MMRL repair during primary ACLR.

Medial meniscal ramp lesions (MMRLs) of the posterior horn of the medial meniscus are peripheral longitudinal/vertical tears ≤3 mm from the meniscocapsular junction.^6,8,23,43,44 These meniscocapsular attachments function to prevent anterior tibial translation, making the ramp area predisposed to tear concomitantly in 9% to 42% of adult anterior cruciate ligament (ACL) tears.^6,9,10,44 These medial meniscal tears are commonly called “hidden lesions” because of difficulty with their diagnosis on physical examination, magnetic resonance imaging (MRI), and standard anterior viewing and probing during diagnostic arthroscopy.^1,17,30 As a missed MMRL may lead to premature ACL graft failure and/or exacerbate further damage to the medial meniscus, many recent studies have aimed to better understand this unique pathology.^{11,13,14,32,44}

Clinical studies on MMRL are primarily confined to adults, and our understanding of these unique tears remains limited in pediatric and adolescent patients. Recently, arthroscopically diagnosed MMRLs have been reported in 13.2% to 28% of pediatric patients undergoing primary ACL reconstruction (ACLR).^1,17,27 Hollnagel et al ¹⁷ reported that concomitant lateral meniscal tears (LMTs) occurred in 68% of their 28 pediatric patients with MMRL and that ≥20% of these LMTs were undiagnosed until surgery. While these 2 meniscal tear types appear to occur frequently together in pediatric patients, the specific characteristics of concomitant LMT at the time of MMRL repair and ACLR are not well-understood in particular patient populations.

The presence of a concomitant LMT in the setting of an MMRL can cause additional biomechanical consequences in an ACL-deficient knee.^19,25,39 For example, in the adult literature, the injury combination of a lateral meniscus root tear (LMRT), MMRL, and ACL tear has been referred to as the “new terrible triad” because of increased rotatory instability, anterior tibial translation, and difficulty with dual meniscal repair techniques during ACLR.^{15,16,19,25,26,39} However, in pediatric and adolescent patients, the tear patterns, location, and surgical management of concomitant LMT at the time of MMRL repair and ACLR are relatively unknown.^26,28 This clinical information could further our understanding of these combination meniscal injuries in younger patients who are the highest risk population for meniscal repair and ACL graft failure.^2,4 As such, the purpose of this multicenter study was to describe the characteristics and surgical management of concomitant LMT in pediatric patients undergoing a combined primary ACLR and MMRL repair. The authors hypothesized that >50% of these patients with concomitant LMT would undergo a lateral meniscal repair at the time of surgery.

Methods

Patient Selection and Identification

Institutional review board approval and multicenter data-sharing agreements were accepted and granted at the following 5 study institutions (Yale School of Medicine, Hospital for Special Surgery, Texas Children's Hospital, Rush University Medical Center, and Twin Cities Orthopedics). Surgical records were retrospectively reviewed to identify all patients aged <18 years old (at the time of surgery) who underwent an MMRL repair during ACLR at 1 of the 5 study institutions from June 2013 to January 2025. Patient data were queried across 8 different orthopaedic surgeons (4 board-certified pediatric and sports medicine fellowship trained and 4 board-certified sports medicine fellowship trained) from the 5 separate institutions.

Each operative note was independently reviewed by 2 authors (J.M. and J.Z.A.) to confirm sufficient documentation meeting the definition of an MMRL. Based on an established arthroscopic definition in the literature, an MMRL was defined as a partial or complete peripheral vertical/longitudinal tear of the posterior horn of the medial meniscus ≤3 mm from the meniscocapsular junction in the red-red zone, identified and repaired arthroscopically at the time of ACLR. During the study period, all surgeons routinely performed a modified Gillquist maneuver or accessory posteromedial portal to assess the posteromedial compartment during diagnostic arthroscopy on every patient undergoing ACLR and routinely repaired MMRL when encountered.

In cases of disagreement between the 2 reviewers on the definition of an MMRL, the senior author (R.F.L.) made the final decision to include or exclude the patient of interest. Once the initial cohort was identified, patients were then excluded from the study for any of the following criteria: concomitant periarticular fractures (not including bone bruises or subchondral insufficiency fractures); concomitant medial meniscal tears that were complex or extended into the body, anterior horn, or roots; revision ACLR; incomplete, ambiguous, and/or missing surgical documentation to classify and confirm the presence of an MMRL and repair; history of congenital lower extremity abnormalities; diagnosis of ipsilateral discoid meniscus; previous ipsilateral knee surgeries or injuries; and concomitant surgeries at the time of ACLR including medial patellofemoral reconstruction, multiligament reconstruction/repair (medial collateral ligament, posterior cruciate ligament, and fibular [lateral] collateral ligament reconstruction, or complete posterolateral corner injury), osteotomies, or tibial eminence avulsion fractures.

Preoperative and Intraoperative Data Collection

The following patient characteristics were collected on each patient who satisfied the inclusion criteria and did not meet the exclusion criteria: age at the time of surgery, sex (male or female), time between the initial injury and ACLR (defined as acute ACLR, <6 weeks; subacute, ≥6 weeks to <12 weeks; and chronic ≥12 weeks),^1,2 body mass index (BMI) and respective BMI percentiles according to sex and age, number of patients classified as obese (≥95th percentile for BMI in their respective age and sex group), ³ mechanism of injury (contact or noncontact), and athletic participation/level of competition at the time of injury.^4,5

Skeletal maturity was classified as mature (closed physes) or immature (open physes) based on preoperative MRI evaluation. ⁶ Physes were considered to be open if there was a band of high signal intensity on T2-weighted images in the expected location of the distal femoral physeal plate. ²⁴ Lateral posterior tibial slope (LPTS) was measured using the anatomic axis and the angle between the tibia and the lateral tibial plateau by each institution using a preoperative lateral radiograph of the knee, and if not available, radiographs from the first postoperative visit were used. ⁷ Knee physical examination findings under anesthesia were collected from the operative notes and included Lachman (1, 2, or 3) and pivot-shift grades (0, 1, 2, or 3). The type of MMRL repair technique was also recorded.

Assessment of Arthroscopically Identified Concomitant LMT at Time of MMRL Repair and ACLR

All operative notes were also reviewed for the presence or absence of an arthroscopically identified concomitant LMT at the time of MMRL repair during primary ACLR. To standardize the findings, concomitant LMT was categorized by 2 reviewers (J.M. and J.Z.A.) using the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine classification system for meniscal tear patterns (longitudinal/vertical, horizontal, horizontal flap, vertical flap, radial, complex [defined by ≥2 tear patterns], and root tears) and tear location (anterior horn, middle body, posterior horn, and anterior/posterior roots) based on each surgeon's description and diagnosis from the operative notes. ³⁶ Radial tears were further subclassified as partial or complete. The location for lateral meniscal bucket-handle tears was not localized to specific regions given the complete nature of these tears. Lateral meniscus root tears (LMRTs) were defined by a tear extending into or within 1 cm of the meniscus root attachment and was classified using the LaPrade classification (types 1-5). ²⁰ Similarly, for any disagreements between the 2 reviewers, the senior author (R.F.L.) made the final decision (Figure 1). The surgical treatment of concomitant LMT was categorized into 3 groups: observation, meniscectomy (partial or complete), and/or repair. Lateral meniscal repairs were further classified based on the specific technique including inside-out, all-inside, outside-in, and/or transtibial tunnel root repair.

Figure 1.

The LaPrade classification for meniscus root tears. Type 1 (partial stable tears near or at the root attachment site), type 2 (complete radial tears within 1 cm of the root attachment), type 3 (bucket-handle tear with a complete root tear), type 4 (complex partial or complete oblique/radial flap tears with extension into the root attachment), and type 5 (bony root avulsion fracture) (Reproduced with permission from LaPrade et al.). ²⁰

Frequency of Missed Concomitant LMT on the Initial Preoperative MRI Report

In all patients with concomitant LMTs diagnosed on arthroscopy at the time of surgery, the initial preoperative MRI report was retrospectively reviewed for a missed diagnosis of an LMT. Using a similar methodology outlined by Schlechter et al, ³⁷ a preoperative MRI diagnosis of an LMT was considered “missed” if the radiology report distinctly stated a normal-appearing lateral meniscus without any mention of a possible LMT. These numbers were then used to calculate the percentage of patients who had concomitant LMTs identified on arthroscopy that were missed on the initial preoperative MRI report. The various percentages of missed LMT on preoperative MRI were further analyzed based on the different LMT types diagnosed on arthroscopy.

Risk Factor Analysis

Patients were then stratified into 2 cohorts based on the presence or absence of a concomitant LMT. The following potential risk factors associated with concomitant LMT were then assessed: male (vs female) sex; obesity (vs no obesity), chronic ACLR (vs acute and subacute ACLR), contact mechanism of injury (vs noncontact mechanism), skeletal maturity (vs skeletally immature), LPTS ≥12 degrees (vs <12 degrees), and grade 3 pivot-shift or Lachman.

Statistical Analysis

Bivariate Analysis

The Real Statistics Add-in Package in Microsoft Excel (Microsoft Corp) was used to conduct all bivariate analyses. Continuous variables were assessed using 2-tailed t test or their nonparametric equivalents, and categorical variables were assessed using chi-square or Fisher exact tests. Statistical significance was defined as P≤ .05. These analyses were used to describe the cohort and screen for potential associations between individual factors and the presence of concomitant LMT.

Multivariable Analysis

To evaluate independent risk factors for concomitant LMT, we performed Firth penalized likelihood logistic regression, which reduces bias in small sample size and separation. ³⁴ Variables were initially selected based on clinical relevance, bivariate results, and established associations from previous literature. To avoid multicollinearity, we did not include redundant or highly correlated variables (eg, acuity of injury and time from injury to surgery) in the same model. A full model was first constructed, and model optimization was then guided by the Akaike Information Criterion, Bayesian Information Criterion, model significance, and predictive performance. Linearity between continuous variables and the logit of the outcome was confirmed using the Box-Tidwell procedure.

The final multivariable model retained only variables that contributed meaningfully to model fit and discrimination. Logistic regression analyses were conducted using SAS Version 9.4 (SAS Institute Inc). All other statistical analyses were performed using the Real Statistics Add-in Package. Only variables remaining significant in the final multivariable model are reported, along with corresponding odds ratios (ORs) and 95% CIs.

Results

Cohort Selection and Patient Characteristics

Overall, 238 patients <18 years old who underwent an MMRL repair during ACLR from 2013 to 2025 were identified. In total, 189 patients who underwent a primary MMRL repair during ACLR remained after the inclusion and exclusion criteria were applied and were included in the final analysis (Figure 2).

Figure 2.

Flow diagram describing the selected study cohort. ACLR, anterior cruciate ligament reconstruction; MLKI, musculoskeletal injury; MMRL, medial meniscal ramp lesion.

A summary of the population characteristics and demographics for the study cohort can be seen in Table 1.

Table 1.

Demographics of Cohort Undergoing Primary Medial Meniscal Ramp Lesion Repair and Anterior Cruciate Ligament Reconstruction ^a

	Cohort (N = 189)
Age, y	16.1 ± 1.4 (12.0-17.9)
Sex
Female	86 (46)
Male	103 (55)
BMI Percentile	75.8 ± 21.3 (1.8-99.7)
Obese (≥95th percentile BMI)
Yes	37 (20)
No	152 (80)
Days until surgery	73 ± 71.2 (5-477)
Time to ACLR
Acute (<6 weeks)	82 (43)
Subacute (6 weeks−3 months)	55 (29)
Chronic (≥3 months)	52 (28)
Mechanism of injury
Contact	42 (22)
Noncontact	147 (78)
Skeletal maturity
Immature (open)	30 (16)
Mature (closed)	159 (84)
Sport at time of injury
Soccer	49 (26)
Basketball	49 (26)
Football	33 (18)

^aData are reported as mean ± SD (range) or n (%). BMI, body mass index; LMT, lateral meniscal tear; MMRL, medial meniscal ramp lesion.

Surgical Data on Concomitant LMT at Time of MMRL Repair During ACLR

During primary ACLR, the 2 techniques utilized for MMRL repair were all-inside (80%) and inside-out (20%). Concomitant LMT was arthroscopically identified in 122 (65%) patients. The tear patterns and location of the arthroscopically identified LMTs are described in Table 2. For the 15 lateral meniscal radial tears, 10 were partial while 5 were complete. Furthermore, nearly half of the concomitant LMTs diagnosed in this cohort were posterior LMRT (25%), complex nonroot tear (15%), complete radial tear (4%), or bucket-handle tear (4%).

Table 2.

Concomitant Lateral Meniscal Tear Patterns and Location Diagnosed on Arthroscopy at the Time of Medial Meniscal Ramp Lesion Repair During Anterior Cruciate Ligament Reconstruction ^a

Concomitant LMT	(n = 122)
LMT pattern
Vertical/longitudinal	50 (41)
Root	31 (25)
Complex	18 (15)
Radial	15 (12)
Bucket-handle	5 (4)
Horizontal flap	2 (2)
Vertical flap	1 (1)
LMT location (n = 117 b )
Anterior horn	6 (5)
Body	9 (8)
Posterior horn	71 (61)
Posterior root	31 (27)

^aData are reported as n (%). LMT, lateral meniscal tear.

^bLateral meniscal bucket-handle tears were excluded from LMT location because of the complete nature of the tear.

Overall, the majority of concomitant LMTs were surgically repaired (67%) while fewer underwent a partial meniscectomy (27%). The remaining concomitant LMTs (6%) were left for observation and deemed healed and stable and were subsequently left untreated (Table 3).

Table 3.

Surgical Management of Concomitant Lateral Meniscal Tears During Pediatric Combined Anterior Cruciate Ligament Reconstruction and Medial Meniscal Ramp Lesion Repair ^a

Concomitant LMT	(n = 122)
LMT surgical treatment
Repair	82 (67)
Partial meniscectomy	33 (27)
Observation	7 (6)
LMT repair technique (n = 82)
All-inside	55 (67)
Inside-out	16 (20)
Transtibial tunnel	10 (12)
All-inside/outside-in	1 (1)

^aData are reported as n (%). LMT, lateral meniscal tear.

In total, posterior LMRTs were diagnosed on arthroscopy and surgically treated in 16% (31/189) in those undergoing a combined MMRL and primary ACLR. Further, posterior LMRTs made up 25% of the concomitant LMTs in the cohort. Details regarding the specific types and surgical management of LMRT are described in Table 4.

Table 4.

Classification and Surgical Treatment of Concomitant Lateral Meniscus Posterior Root Tears at the time of Medial Meniscal Ramp Lesion Repair During Anterior Cruciate Ligament Reconstruction ^a

Concomitant LMT	(n = 122)
LMRT
Yes	31 (25)
No	91 (75)
LMRT LaPrade type (n = 31)
Type 1 (partial stable)	2 (6)
Type 2 (complete radial root tear)	8 (26)
Type 3 (bucket-handle with complete root tear)	0 (0)
Type 4 (complex oblique/radial flap root tear)	20 (65)
Type 5 (bony root avulsion fracture)	1 (3)
LMRT treatment (n = 31)
Partial meniscectomy	11 (36)
All-inside repair	10 (32)
Transtibial tunnel repair	10 (32)

^aData are reported as n (%). LMRT, lateral meniscus root tear; LMT, lateral meniscal tear.

Of the 31 posterior LMRTs diagnosed, type 4 complex oblique and/or radial flap tears that extended into the posterior root attachment (n = 20; 65%) were the most common and more than half (55%) were treated with a repair (n = 11 [9 all-inside side-to-side repairs, 2 transtibial tunnel root repairs]) as opposed to a partial meniscectomy (45%) (Figure 3). Type 2 complete radial root tears near the posterior root attachment (n = 8; 26%) and a type 5 bony posterior root avulsion (n = 1; 3%) were all repaired (8 transtibial tunnel root repairs, 1 all-inside repair) while type 1 partial stable posterior root tears (n = 2; 7%) underwent a partial meniscectomy (Figure 4). Overall, 65% (20/31) of concomitant posterior LMRTs were repaired while 35% underwent a partial lateral meniscectomy (Figure 5 and 6).

Figure 3.

Arthroscopic examples showing a concomitant (A) complex complete oblique lateral meniscus posterior root tear (LaPrade Type 4) and (B) complete radial lateral meniscus posterior root tear (LaPrade Type 2) in pediatric patients who underwent primary lateral meniscus posterior root repair−medial meniscal ramp lesion repair−anterior cruciate ligament reconstruction.

Figure 4.

Arthroscopic images from a 13-year-old girl who underwent anterior cruciate ligament reconstruction with (A) a concomitant medial meniscal ramp lesion (MMRL) showing the meniscocapsular separation diagnosed on arthroscopy (black arrow in figure 4A) and (B) mattress repair with an all-inside, capsular-based, self-tensioning repair technique (black arrow in figure 4B). MFC, medial femoral condyle; PMC, posteromedial capsule.

Figure 5.

Arthroscopic example of a right knee showing a degenerative partial type 4 complex oblique lateral meniscus root tear with extension into the posterior root attachment (black arrow) in a 15-year-old male patient undergoing anterior cruciate ligament reconstruction and medial meniscal ramp lesion repair. Permission granted from copyright owner, Peter D. Fabricant, MD, MPH, Hospital for Special Surgery, Division of Pediatric Orthopedic Surgery.

Figure 6.

Arthroscopic examples of a right knee in a skeletally immature 14-year-old female undergoing anterior cruciate ligament reconstruction with (A) type 5 bony root avulsion posterior lateral meniscus root tear, (B) suture passage, (C) reapproximating with tensioning, and (D) the final transosseous tibial tunnel lateral meniscus posterior root repair. The patient also had (E) an unstable medial meniscal ramp lesion that was (F) repaired with an all-inside technique. Permission granted from copyright owner, Peter D. Fabricant, MD, MPH, Hospital for Special Surgery, Division of Pediatric Orthopedic Surgery.

Frequency of Missed Concomitant LMT on the Initial Preoperative MRI Report

Overall, of the 122 arthroscopically diagnosed concomitant LMTs, 31% were categorized as missed on the initial preoperative MRI report. Specifically, vertical/longitudinal LMT had the highest frequency of being missed (40%), followed by LMRT (29%), complex nonroot tear (22%), and radial tear (13%). The remaining LMT configurations had no missed diagnoses on the initial preoperative MRI report.

Risk Factor Analysis and Multivariable Logistical Regression

A comparison of the demographics between those with and without concomitant LMT can be seen in Table 5.

Table 5.

Bivariate Analysis Between Patients With Concomitant LMT Compared With Those Without Concomitant LMT at time of Medial Meniscal Ramp Lesion Repair and Anterior Cruciate Ligament Reconstruction ^a

	Concomitant LMT (n = 122)	No LMT (n = 67)	P
Age, y	16.2 ± 1.3 (12.4-17.9)	16.0 ± 1.5 (12.0-17.9)	.30
Sex			.01
Female	47 (39)	39 (58)
Male	75 (62)	28 (42)
BMI percentile	76.5 ± 22.6 (1.8-99.7)	74.6 ± 18.9 (15.2-99.5)	.55
Obese			.02
Yes	30 (25)	7 (10)
No	92 (75)	60 (90)
Days until surgery	70 ± 68.7 (5-477)	79 ± 75.8 (11-338)	.43
Acuity of injury			.48
Acute	50 (41)	32 (48)
Subacute	39 (32)	16 (24)
Chronic	33 (27)	19 (28)
Mechanism of injury			.97
Contact	27 (22)	15 (22)
Noncontact	95 (78)	52 (78)
Status of physes			.88
Open	19 (16)	11 (16)
Closed	103 (84)	56 (84)
Lateral Posterior Tibial Slope			.85
≥12°	38 (31)	20 (30)
<12°	84 (69)	47 (70)
Grade 3 pivot or Lachman			.16
Yes	33 (27)	12 (18)
No	89 (73)	55 (82)

^aData reported as mean ± SD (range) or n (%). Bold P values indicate statistical significance at P < .05. LMT, lateral meniscal tear.

Logistic Regression

The following variables were imputed into the regression: age, sex, obesity, acuity of knee injury, lateral tibial posterior slope, and grade 3 pivot shift (Table 6).

Table 6.

Significant Variables Found in Regression ^a

Variable	Odds Ratio	P	Lower 95% CI	Upper 95% CI
Male sex	1.93	.044	1.02	3.68
Obesity	2.49	.046	1.02	6.10

^aData are reported as n. Bold indicates statistical significance at P≤ .05.

Discussion

The most important finding of this multicenter study was that a concomitant LMT was arthroscopically diagnosed in 65% of pediatric patients undergoing MMRL repair during ACLR. In addition, 31% of these concomitant LMTs were missed on the initial preoperative MRI report. The vast majority (86%) of LMTs occurred at the posterior horn (61%) or posterior root (27%). While vertical/longitudinal tears were the most common LMT pattern (41%), there was a high frequency of the more serious tear morphologies including LMRTs (25%), complex nonroot tears (15%), complete radial tears (4%), and bucket-handle tears (4%). Furthermore, nearly 1 in every 6 with MMRLs had a concomitant LMRT, with the majority being type 4 complex oblique root tears. Overall, most concomitant LMTs were treated with surgical repair (67%) as opposed to partial meniscectomy (27%) or observation (6%), which supported our primary hypothesis. Last, male sex and obesity were 2 significant risk factors associated with the presence of a concomitant LMT. These findings provide clinically relevant information that could help improve the recognition and surgical management of LMTs in pediatric patients with MMRLs, especially because many were missed on the initial MRI report.

The current study found that 65% of pediatric patients undergoing MMRL repair during ACLR were diagnosed with a concomitant LMT at the time of surgery. These findings are in agreement with those recently published by Hollnagel et al ¹⁷ who arthroscopically diagnosed a concomitant LMT in 68% of 28 pediatric patients with MMRLs. While detailed descriptions of the patterns and surgical management of LMT-MMRL-ACL injuries are lacking for this population, the current study found that vertical longitudinal LMTs (41%) were the most common tear morphology and nearly all (98%) localized to the posterior horn. In addition, a high percentage (84%) of these particular LMTs were repaired, either with all-inside (83%) or inside-out techniques (17%), as they frequently occurred in the red-red and red-white zones. However, it is important to acknowledge that these vertical/longitudinal LMTs had the highest frequency (40%) of being missed on the initial preoperative MRI report. Overall, nearly 1 out of every 4 pediatric patients with MMRLs will require a concomitant lateral meniscal repair for a vertical/longitudinal tear at the posterior horn, even if the preoperative MRI suggests a normal-appearing lateral meniscus.

In adult patients undergoing an MMRL repair during ACLR, DePhillipo et al ⁷ reported that 22% had a concomitant LMRT. Similarly, the current study found that 1 in every 6 (16%) pediatric patients with MMRLs were arthroscopically diagnosed with an LMRT. Similar to a MMRL, diagnosing LMRTs preoperatively on MRI can be challenging, with variable reported sensitivities and specificities throughout the pediatrics literature.^29,31,37 Schlechter et al ³⁷ reported that a definitive posterior LMRT diagnosis on preoperative MRI was not made in 76% of pediatric patients with an arthroscopically confirmed posterior LMRT. Additionally, Nguyen et al ²⁹ found that 12 of 39 (31%) arthroscopically confirmed LMRTs in pediatric patients were not diagnosed on preoperative MRI. Similarly, the present study found that 9 of 31 (29%) LMRTs diagnosed on arthroscopy were missed on the initial preoperative MRI report. As such, surgeons should be aware that LMRTs are not uncommon in pediatric patients with MMRLs, even in the setting of a normal-appearing lateral meniscus on preoperative MRI.

The LaPrade type 4 complex root tear or lateral meniscus oblique radial tears (LMORT), defined as partial or complete complex oblique/radial flap tears that extend into the root attachment, was the most common (65%) LMRT diagnosed at the time of MMRL repair during ACLR.^20-22 These findings are in contrast to 2 recent studies that have reported type 2 complete radial posterior root tear as the most common LMRT seen in pediatric ACL tears (without MMRLs).^5,46 In comparison with the concomitant type 2 radial LMRTs, which were all repaired in the present study, the surgical management of LMORTs/type 4 complex oblique posterior LMRTs are not well reported in pediatric patients undergoing ACLR, and especially in the setting of a concomitant MMRL. It is important to note that an additional 15% of the concomitant LMTs in the present study were separately defined as complex nonroot tears and were more consistent with the LMORT types that are >1 cm from the root attachment.^3,18,42

In the current study, 55% of concomitant type 4 complex LMRTs were treated with a surgical repair with the majority being all-inside side-to-side repairs (82%) as opposed to transosseous tibial tunnel repairs (18%). In contrast, 45% underwent a partial lateral meniscectomy most commonly due to the degenerative appearance of the complex flap and for tears that only compromised 25% to 50% of the posterior root attachment rather than a complete detachment. It is reassuring to note that all patients who underwent a partial meniscectomy had some degree of posterior root remaining that was stable with arthroscopic probing. It is equally important to note that the current study included patients starting from 2013 where the surgical treatment guidelines on type 4 LMRTs/LMORTs may have been even less defined than the present day; as such, these findings should be interpreted within the context of these study parameters. Given our enhanced understanding and resultant paradigm shift toward meniscal preservation in the past decade for pediatric patients, surgeons should strongly consider repairing these concomitant partial complex LMRTs whenever possible to prevent any potential long-term consequences associated with meniscectomy of root tears^{12,31,33,38,40,41,45}; however, further clinical outcomes are still needed to improve the management of these complex root tears/LMORTs in pediatric patients undergoing MMRL repair during ACLR.

Last, the present study sought to identify risk factors associated with the presence of concomitant LMT in patients undergoing an MMRL repair during ACLR. Male sex (OR, 1.9) and obesity (defined by ≥95th percentile for BMI) (OR, 2.5) were the only 2 significant variables when multivariable logistical regression was utilized. In the present study, 25% of those with concomitant LMTs were categorized as obese compared with 10% in those without concomitant LMTs. We found no difference between those with and without concomitant LMTs when comparing the mechanism of injury, chronicity of injury, lateral posterior tibial slope, skeletal maturity (open vs closed physes), and physical examination findings such as a grade 3 pivot or Lachman test. Rohde et al ³⁵ reported in a large multicenter study that pediatric patients with obesity underwent significantly higher rates of complex meniscal tear repairs and male patients were significantly more likely to undergo lateral meniscal repairs than their female counterparts. Similarly, surgeons should be aware of these potential risk factors for concomitant LMT tears in pediatric patients undergoing a combined MMRL repair and ACLR that were found in the present study. However, further studies with larger cohorts are still needed to better elucidate the risk factors for concomitant LMT associated with MMRLs and ACL tears in these young patients.

Limitations

This multicenter study has important limitations, including its retrospective cohort design. Given the small number of patients without concomitant LMTs, our analysis may have been susceptible to a type II error when identifying risk factors associated with LMTs. Patients were collected from the practices of 8 sports surgeons, each employing their preferred operative note template, descriptions of LMTs, repair techniques, implants, and surgical treatment, which introduces a degree of heterogeneity. While retrospective assessment of arthroscopic images may have provided a more accurate categorization of the tear patterns, intraoperative images were not available for every patient, as the study period included patients from 2013 when many institutions did not have digital storage of arthroscopic photos. Only the initial radiology report was retrospectively reviewed to determine the number of missed diagnoses of concomitant LMT, and further studies are needed to determine avoidable errors with MRI diagnosis. Last, the vast majority of pediatric patients in our cohort participated in athletics, and the different sport types may have influenced the presence and presentation of concomitant LMTs. However, we were unable to find any meaningful association with sport type because of the high number of different sports and our limited number of patients.

Conclusion

In this multicenter study, 65% of pediatric and adolescent patients undergoing MMRL repair during primary ACLR had a concomitant LMT and the majority were localized to the posterior horn and posterior root. As 31% of concomitant LMTs were missed on preoperative MRI, the posterior aspect of the lateral meniscus should be carefully evaluated at the time of surgery in pediatric patients with MMRLs. Nearly half of the concomitant LMTs identified in this cohort were LMRTs, complex tears, complete radial tears, or bucket-handle tears. Overall, surgeons should anticipate performing an additional lateral meniscal repair in nearly half of pediatric patients undergoing an MMRL repair during primary ACLR.