Medial Meniscus Root Tear: Current Update Review

This chapter mainly focuses on medial meniscus posterior root tear which is the point of attention nowadays because it is the common degeneration process and can lead to early-onset osteoarthritis of the knee without treatment. The biomechanics of the medial meniscus root tear is similar to total meniscectomy. Hence, early detection and diagnosis will lead to better outcome. Most cases with medial meniscus root tear also have degenerative change of the knee. Meniscal extrusion is a common finding in magnetic resonance imaging (MRI) which represent impairing of hoop stress function of the meniscus. Patient selection and understanding of the natural history of the disease is a particularly important. Options for the treatment including conservative treatment, surgical treatment such as partial meniscectomy, meniscus root repair, or reduction of meniscal extrusion. Outcome of these treatments are variable depending on the condition of the patients. Long term outcome of surgical treatment revealed lower rate of knee replacement compared with conservative treatment.

Mild to Moderate Varus Alignment in Relation to Surgical Repair of a Medial Meniscus Root Tear: A Matched-Cohort Controlled Study With 2 Years of Follow-up

Background: Increased varus alignment of the lower extremity is known to be a poor prognostic factor for the surgical repair for a medial meniscus root tear (MMRT). However, given the concept of constitutional varus, which is present in a substantial portion of the normal population, the generally accepted surgical indication for MMRT concerning a varus alignment of 5° may be unnecessarily narrow. Purpose: To compare the surgical outcomes of arthroscopic transtibial pullout repair of MMRT according to the degree of varus alignment of the lower extremity. Study Design: Cohort study; Level of evidence, 3 Methods: Patients who underwent isolated arthroscopic transtibial pullout repair of MMRT between January 2010 and July 2017 at one institution and had a minimum follow-up of 2 years were included in this study. Patients were classified into 1 of 2 groups: the experimental group (n = 22) included patients with a preoperative hip-knee-ankle angle between 5° and 10° varus (mild to moderate varus alignment) and the control group (n = 51) included those with a preoperative hip-knee-ankle angle <5° varus (neutral alignment). Clinical scores and radiographic parameters were compared between the groups to assess surgical outcomes, which were statistically matched for potential confounders (age, body mass index, the severity of cartilage lesion) by use of the inverse probability of treatment weighting. A noninferiority trial was performed comparing the experimental and control groups in terms of subjective outcomes (International Knee Documentation Committee subjective and Lysholm scores) and objective outcomes (postoperative medial meniscal extrusion and the rate of osteoarthritis progression). Results: There were no statistically significant differences in surgical outcomes between the groups in subjective and objective aspects, which were consistent before and after inverse probability of treatment weighting. Apart from the clinical improvement observed in both groups, overall degenerative changes in the knee were found, although progression rates did not differ between the groups. In terms of the noninferiority trial, the overall surgical outcomes in the experimental group were not inferior to those in the control group. Conclusion: The short-term surgical outcomes of arthroscopic transtibial pullout repair for MMRT of patients with mild to moderate varus alignment were not inferior to but rather comparable with those with neutral alignment in terms of subjective and objective aspects. Therefore, it would be inappropriate to exclude patients with a diagnosis of MMRT from being indicated for the surgery simply because of mild to moderate varus alignment.

Posterior Medial Meniscus Root Tears Potentiate the Effect of Increased Tibial Slope on Anterior Cruciate Ligament Graft Forces

Background: Increased posterior tibial slope and posterior medial meniscus root tears increase the force experienced by the anterior cruciate ligament (ACL) and predispose patients to higher rates of primary ACL injury or ACL graft failure after an ACL reconstruction (ACLR). However, the interplay among sagittal plane tibial slope, medial meniscus root tears, and ACLR graft force remains inadequately defined. Purpose/Hypothesis: The purpose was to quantify the effect of sagittal plane tibial slope on ACLR graft force at varying knee flexion angles with an intact medial meniscus, a posterior medial meniscus root tear, and a medial meniscus root repair. Our null hypothesis was that changes in slope and meniscal state would have no effect on the forces experienced by the ACLR graft. Study Design: Controlled laboratory study. Methods: Ten male fresh-frozen cadaveric human knees underwent a posteriorly based high tibial osteotomy. A spanning external fixator and wedges of varying sizes were used to stabilize the osteotomy and allow for accurate slope adjustment. After ACLR, specimens were compressed with a 1000-N axial load at flexion angles of 0° and 30° for each of the 3 meniscal states and at tibial slopes of 0° to 15° at 3° increments. Graft loads were recorded through a force transducer clamped to the graft. Results: Increasing tibial slope led to a linear increase in ACLR graft force at 0° and 30° of knee flexion. Posterior medial meniscus root tear led to significant increases in ACLR graft forces over the intact state, while root repair restored the function of the medial meniscus as a secondary stabilizer. At 30° of knee flexion, the tibial slope effect on ACLR graft force was potentiated in the root tear state as compared with the intact and root repair states—test of interaction effect: t(139) = 2.67 ( P = .009). Conclusion: Increases in tibial slope lead to a linear increase in ACLR graft forces, and this effect is magnified in the setting of a posterior medial meniscus root tear. At slopes >12°, a slope-changing osteotomy could be considered in the setting of a revision ACLR with a concomitant medial meniscus root tear. Clinical Relevance: Defining the relationship between tibial slope and varying states of meniscal insufficiency can help determine when it may be necessary to perform a slope-decreasing proximal tibial osteotomy before ACLR and meniscal repair.

Understanding the Implications of the Meniscal Ossicle: Patient Presentation, Treatment, and Outcomes

The meniscal ossicle is observed in clinical practice, yet there currently is limited information on its potential clinical significance. The purpose of this study was to assess the clinical presentation, imaging findings, and clinical treatment and outcomes of a series of patients identified as having a meniscal ossicle. An institutional database was reviewed to identify knees with a meniscal ossicle. Clinical presentation, magnetic resonance imaging (MRI), treatment, and outcomes were analyzed. Radiographs were graded using Kellgren–Lawrence (KL) scores. MRIs were reviewed for the presence and location of meniscal ossicles and additional knee pathology. Knee arthroplasty rates were recorded with the remaining patients contacted to obtain final International Knee Documentation Committee (IKDC) and Tegner's scores. Failure was defined as conversion to arthroplasty or failing IKDC score (< 75.4). Forty-five meniscal ossicles in 45 patients (26 males and 19 females) with a mean age of 51 years (standard deviation [SD] = 19.0) were included. Pain was the most common presenting symptom (89%). Forty-two patients (93%) had an associated meniscus root tear on MRI. Eighteen percent of patients that did not have an ossicle on initial imaging subsequently developed an ossicle. Mean KL grades progressed significantly from baseline of 1.84 (SD = 1.0) to 2.55 (SD = 0.93 p < 0.01) on final follow-up. Thirty-nine percent of baseline radiographs showed KL grades of less than 2 compared with only 15% of follow-up radiographs (p = 0.04). Mean IKDC score obtained for patients ≤ 60 at an average follow-up of 3.1 years (SD = 3.2) was 65.2 (SD = 19.0). Eight out of 45 patients (18%) had progressed to total knee arthroplasty (TKA) by latest available follow-up. Sixty-two percent of patients met failure criteria at latest available follow-up. The meniscal ossicle is most commonly found in the posterior horn or root of the medial meniscus and is highly suggestive to be sequelae of a posterior root tear. Therefore, the presence of a meniscal ossicle should alert the orthopaedic surgeon to the high likelihood of the patient having a meniscus root tear. These patients have shown to have poor clinical outcomes and worsening arthritis.

Worsening of Radiographic Knee Osteoarthritis Following Medial Meniscus Root Tears and Non-Root Tears

Objectives: Medial meniscus root tear has an established association with knee osteoarthritis (OA), but little is known about the time course of cartilage breakdown or the severity of cartilage damage when compared to meniscal tears which spare the root. The aims of this study were to compare early progressive radiographic degenerative changes in knees with medial meniscus root tears (RT) and medial meniscus tears sparing the root (non-root tears: NRT), and identify risk factors for osteoarthritic progression among patients with RT. Methods: A convenience sample of 3,121 knees from 2,656 participants was drawn from the NIH-funded multicenter Osteoarthritis Initiative (OAI) database. All knees with medial meniscus RT or NRT seen on initial baseline MRI (prevalent) or on subsequent visit MRI (incident) were included. Demographics including sex, age, body mass index (BMI), activity level, knee injury, and knee pain were recorded at index visit (visit at which meniscal injury was first seen) and compared between prevalent RT versus NRT and incident RT versus NRT groups. Radiographic OA worsening was defined as an increase in Kellgren-Lawrence Grade (KLG) at any time from the last normal MRI 12 months before meniscal tear diagnosis (T-12, available in incident tears only) to the index visit (T0), to follow-up MRI 12 months after meniscal tear diagnosis (T+12). Additionally, characteristics of RT patients with OA worsening were compared to those who did not have progressive degenerative changes. Continuous variables were compared using a student’s t-test. Categorical data were compared using Fisher’s exact and chi-squared tests. Results: Within the OAI database, 78 medial meniscus RTs (45 prevalent, 33 incident) were identified, along with 1,030 medial meniscus NRTs (775 prevalent, 255 incident). 75% of incident RTs and 40.9% of incident NRTs (p<0.0001) demonstrated radiographic OA worsening in the 24 months studied, most often concurrent with the medial meniscus root tear, progressing between the last pre-injury MRI (T-12) and the index visit (T0) (Figure 1). As compared to incident NRT, patients with incident RT were more often female, heavier, had a higher activity level, a history of knee injury, and a higher KLG (table 1). Prevalent RT and NRT groups were similar in demographics and rates of radiographic OA worsening. Demographics of patients with incident RT that underwent radiographic OA progression versus those which did not progress were similar with no significant difference in sex, age, BMI, activity level, or history of knee injury and frequent knee pain. The OA progression knees were significantly more likely to have KLG of 0 -1 on pre-RT radiographs than the group that did not progress (66.7% versus 12.5%, p=0.01). Conclusion: For participants with incident medial meniscus tear during the 4-years of OAI, RTs were associated with significantly more progression of radiographic OA than NRTs. A majority of individuals with RTs deny a severe knee injury in the twelve months preceding MRI diagnosis the tear. Compared to incident NRTs, incident RTs were significantly more likely to occur in overweight and more active women, in knees with more severe radiographic OA, and had substantially worse radiographic outcome. Knees which demonstrated radiographic OA progression after incident RT were more likely to have a normal baseline KLG than those which did not progress, but otherwise there were no significant demographic predictors of OA worsening following RT. [Table: see text][Figure: see text]

MENISCUS ROOT TEARS IN CHILDREN AND ADOLESCENTS

Background: The medial and lateral menisci function to optimize force transmission across the knee by increasing contact area between the femur and tibia, absorbing shock, and transmitting loads. Injuries to the meniscus root attachments result in extrusion of the meniscus, impaired distribution of hoop stresses, and degenerative articular wear. The purpose of this study is to describe meniscus root tears, associated injuries, and treatment in a series of pediatric patients Methods: A single-institution retrospective review was performed of consecutive pediatric patients treated for meniscus root tears from 2013 – 2017. Inclusion criteria were patients less than 19 years of age, arthroscopic evidence of a meniscus root tear, and minimum 6 months clinical follow-up. The primary outcome was surgery for revision of the meniscus repair. Results: Twenty-seven patients were identified to fit inclusion criteria. There were 15 males and 12 females with a mean age of 15.2 years (range 7 – 18 years). Basketball, soccer, and football accounted for the majority (56%) of injuries. The lateral meniscus was involved in 21 patients (78%) and the medial meniscus in 6 patients (22%). The posterior meniscus root was torn in 25 patients (93%) and anterior meniscus root in 2 patients (7%). The most common injury pattern was a lateral meniscus posterior root tear (19 patients, 70%). Associated injuries included an ACL tear (19 patients, 70%), PCL tear (6 patients, 22%), and a tear of the opposite meniscus (7 patients, 26%). Two root tears occurred in isolation, and both were of the posterior root of the medial meniscus. All patients were treated surgically with an arthroscopic transosseous root repair in addition to simultaneous treatment for their associated injuries. Mean follow-up was 14 months (range 6 – 37 months). No patients required additional surgery for their meniscus root tear. Two patients had a second surgery on the affected knee: one for revision ACL reconstruction 2 years following the primary procedure and the other for chondroplasty of the patella 2.5 years following the primary procedure. Conclusions: Meniscus root tears occur in pediatric and adolescent patients, most commonly affecting the posterior root of the lateral meniscus and occurring in association with ACL tears. The adolescent meniscus root injury pattern is unique compared to the adult population in which the medial meniscus posterior root is often injured in isolation. Inspection of the meniscus root attachments with deliberate probing to assess the meniscus roots should be a routine part of every knee arthroscopy. In our case series, transosseous root repair resulted in successful outcomes in all patients without need for any additional meniscus treatment.