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Concise Review With Video Illustration

Meniscal Root Tears: Diagnosis and Treatment

Jonathan H. Koenig, B.A., Anil S. Ranawat, M.D., Hilary R. Umans, M.D.,and Gregory S. DiFelice, M.D.

Abstract: Meniscal tears within the body of the meniscus or at the meniscocapsular junctionrepresent a well-understood and manageable condition encountered in clinical practice. In compar-ison, however, meniscal root tears (MRTs) often go unnoticed and represent a unique injury patternwith unique biomechanical consequences. Though first described decades ago, improvements inmagnetic resonance imaging and arthroscopy have only recently enhanced our diagnostic andtreatment capabilities with regard to MRTs. This review contains an anatomic description of the rootsincluding their significance in meniscal function as well as the consequences of their loss. In addition,how to properly identify MRTs and when it is appropriate to surgically repair them are described.Finally, we review the surgical techniques available in the existing literature and present anillustrative case. Key Words: Meniscus—Meniscal root—Root tear—Extrusion—Avulsion—Me-niscal repair.

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ost meniscal tears occur within the body of themeniscus or at the meniscocapsular junction. A

ariety of different patterns have been described. Me-iscal root tears (MRTs) are considered radial tears, orvulsions, at the insertion of the meniscus and ofteno unnoticed. MRTs represent a unique injury patternith unique biomechanical consequences.1-3

The meniscal ossicle, or avulsion injury of the me-iscal insertion site with a small bony fragment, is a

From Research (J.H.K.) and the Department of Orthopaedicurgery, Sports Medicine and Shoulder Service (A.S.R.), Hospitalor Special Surgery, New York, New York; Department of Radio-ogy, Jacobi Medical Center (H.R.U.), Bronx, New York; andepartment of Orthopaedic Surgery, Lenox Hill Hospital (G.S.D.),ew York, New York, U.S.A.The authors report no conflict of interest.Address correspondence and reprint requests to Gregory S.iFelice, M.D., Department of Orthopaedic Surgery, Lenox Hillospital, 130 E 77th St, 11th Floor William Black Hall, New York,Y 10021, U.S.A. E-mail: gdifelice@hotmail.com© 2009 by the Arthroscopy Association of North America0749-8063/09/2509-8693$36.00/0doi:10.1016/j.arthro.2009.03.015

Note: To access the supplementary video accompanying this

hreport, visit the September issue of Arthroscopy at www.arthroscopyjournal.org.

Arthroscopy: The Journal of Arthroscopic and Related Surg

imilar injury that was first described in 1935 based onlain radiographs.4 However, soft-tissue injury to theeniscal roots was not described until the use ofagnetic resonance imaging (MRI) began enhancing

ur diagnostic capabilities. In 1991 Pagnani et al.5

escribed isolated soft-tissue injury to the meniscaloot with associated fixed meniscal extrusion in a0-year-old football player. They treated this conser-atively and hypothesized that this would result inapid progression of degenerative chondral wear.

With the advancing technology in MRI and arthros-opy, our awareness and ability to identify injuries tohis critical area,6-10 to understand the biomechanicalonsequences of these injuries,1,3,5,7,11-13 and to de-elop strategies to surgically repair them1,3,14-22 arevolving rapidly. Currently, there is a dearth of liter-ture corresponding to MRTs. This article reviews theurrent knowledge base.

ANATOMY AND FUNCTION

Each meniscus has been classically described in 3egments: an anterior horn, a body, and a posteriororn. The structure and microstructure of the menisci

ave been well described. In addition to their menis-

1025ery, Vol 25, No 9 (September), 2009: pp 1025-1032

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1026 J. H. KOENIG ET AL.

ocapsular attachments, there are 4 meniscal root an-hors that firmly attach the medial and lateral meniscio the anterior and posterior tibial intercondylar regionr insert the menisci into this region.11

The anterior root of the medial meniscus has theargest footprint and inserts along the anterior inter-ondylar crest on the anterior slope of the tibia; theosterior root inserts just anterior and medial to theosterior cruciate ligament (PCL) on the posterioredial intercondylar eminence of the tibia. As for the

ateral meniscus, the anterior root inserts in front ofhe lateral tubercle and just lateral to the anteriorruciate ligament (ACL) insertion, with which itlends, whereas the posterior root inserts on the hor-zontal portion of the posterior intercondylar area onhe posterior slope of the lateral tubercle, just posterioro the posterolateral bundle of the ACL.6 It should beoted that the insertion of the posterior root of theateral meniscus can be somewhat variable dependingn the presence of the meniscofemoral ligament.21

The primary biomechanical functions of the meniscire load transmission and shock absorption. They ef-ectively distribute contact forces over the articulatingurfaces by increasing joint surface area. Over half ofhe contact force is transmitted by the larger medialompartment of the femur, with 40% to 70% of theotal weight being absorbed by the menisci alone.23 Inddition to stress dissipation, the menisci also haveell-documented roles in the stability of the knee

oint.5 Meniscal stability is necessary to preserve me-iscal function. The meniscal roots thus aid theseunctions by holding the menisci in place and, asairbank24 described, by serving to resist them “fromlipping away like an orange pip squeezed betweenhe fingers.”

Although there is quite a bit of biomechanicalnowledge of the human meniscus, much of it gleanedrom the meniscal transplant literature, the specificiomechanical consequences of an MRT have onlyecently been elucidated.1,3 Allaire et al.1 and Marzond Gurske-DePerio3 studied the effects of MRTs andheir repairs, showing that a posterior medial MRTaused an increase in tibiofemoral contact pressuresnd in kinematic derangements. According to Allairet al., the medial compartment showed a 25% increasen peak contact pressures, and although the lateralompartment showed no significant changes in contactressures, both compartments showed significant ki-ematic changes due to the MRT. Independently,arzo and Gurske-DePerio confirmed the work of

llaire et al., obtaining comparable results. Further- z

ore, both studies proved that arthroscopic sutureepair restored the peak contact pressures to normalevels, proving the importance of the meniscal roots ineniscal function as well as why early diagnosis and

epair are of vital importance.

IMAGING

MRI has profoundly changed our ability to imagehe meniscal root, thereby allowing us to more accu-ately define both normal and pathologic anatomy.he posterior medial meniscal root is clearly visiblen 2 contiguous coronal magnetic resonance imagess a band of low-signal fibrocartilage anchoring theosterior horn of the medial meniscus (Fig 1A) and isisible but more variable in the sagittal plane.12 Me-iscal root pathology may range from intrasubstanceucoid degeneration with or without superficial fray-

ng and attenuation to partial-thickness or full-thick-ess tears.12,25

To the degree that the meniscal root is torn, frayed,r incompetent, there may be an associated extrusionf the medial meniscal body.9,10,12,25 On the midcoro-al magnetic resonance image, defined by optimalisualization of the midsubstance medial collateraligament (MCL), the medial meniscal body may nor-ally extend central to the articular margin up to 3m (Fig 1B). Greater than 3 mm of displacement of

he medial meniscal body in the midcoronal plane isonsidered pathologic extrusion, often associated withadial tear of the medial meniscus and, specifically,

RT (Fig 2). It should be noted that the anterior hornedial meniscus often normally drapes over the tibialargin; this should not be confused with pathologic

xtrusion.MRI readily shows the normal, intact posterioredial meniscal root (Fig 1). If an MRT is identi-ed,8-10,12,25 one must determine whether there is as-ociated medial compartment degenerative cartilageear, to identify the subset of patients who mightenefit from root repair (Fig 2B). In some individualshe meniscal root may degenerate and tear as a con-equence of primary degenerative arthritis. On thether hand, acute, traumatic root avulsions (Fig 3)ay occur in the setting of MCL injuries, knee dislo-

ations, or reverse Segond fractures.17

Finally, one must differentiate between a true MRTnd a radial tear of the paracentral posterior horn ofhe medial meniscus. The root is vascularized andmenable to repair,26 whereas the paracentral poste-ior horn is not. Thus an acute root tear in the vascular

one has favorable characteristics for repair versus

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1027MENISCAL ROOT TEARS

hronic tears in the avascular paracentral region.herefore discriminating a true MRT from a radial

ear of the paracentral posterior horn is essential when

IGURE 1. Coronal fat-saturated T2-weighted magnetic resonancemages, (A) posteriorly and (B) at the level of the MCL, show theormal, intact medial meniscal root (arrow in A) and absence ofedial meniscal extrusion (arrow in B).

etermining the appropriate course of treatment.(b

INDICATIONS

The indications for MRT repairs are constantlyxpanding. On the lateral side, MRTs have been

IGURE 2. Coronal fat-saturated T2-weighted magnetic resonancemages obtained in the same patient as in Fig 1, 4 months later, (A)osteriorly and (B) at the level of the MCL, show a new tear of theedial meniscal root (arrow in A), new medial meniscal extrusion

small arrow in B), and a new chondral defect at the main weight-earing surface of the medial femoral condyle (large arrow in B).

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1028 J. H. KOENIG ET AL.

ssociated with complete or partial ACL inju-ies11,21,27; thus concomitant ACL reconstruction andateral root repair comprise one indication. On theedial side, there are 2 unique injury patterns and

ndications, one acute and one chronic. An acute me-ial MRT is often associated with a multiligamentousnee injury, specifically a grade 3 tear of the MCL,here the meniscal capsular ligaments are maintainedut the meniscus tears by the root and not near theeep MCL.5 These cases are the clearest indication foroot repair because there is no underlying arthritis inhe compartment. On the other hand, chronic tears areften subtle, seemingly benign twisting knee injurieshat go on to rapid compartment degeneration if notroperly diagnosed.5 These cases are much more dif-cult because there may be some degree of underlyingompartment disease.

In these more chronic injuries, the relation betweenRTs and arthritis remains unclear. In certain casesRT leads to meniscal extrusion even in the settinghere there is no discernible arthritis. In several ret-

ospective reviews of knee MRI, authors reported thatedial femorotibial degenerative arthritis had not yet

eveloped in between 15% and 20% of patients withedial meniscal extrusion.9,12 This suggests that MRTay precede and predispose to the development ofedial compartment degenerative arthritis. This pro-

ides a rationale for MRT repair in these pre-arthritic

atients.2,5,28 However, in most series the majority of s

osterior medial MRTs were associated with medialemorotibial compartment degenerative arthritis.7,9,12,25

n these cases it appears that degenerative arthritiseads to an MRT and eventual extrusion, and thus rootepair is not indicated. Thus it is still unclear whethereniscal extrusion is a phenomenon that causes ar-

hritis or is a byproduct of arthritis, but it is likely thatdistinct populations exist.

TREATMENT AND RESULTS

Traditional treatment of the meniscal ossicle andRT was observation versus complete or partial me-

iscectomy, with predictable improvement in symp-oms, but no long-term follow-up or assessment of therogression of arthritis.5,23,28,29 Over the past 5 years,here has been an increasing interest in surgical repairf tears or avulsions at the meniscal root. Similar tohe literature with regard to rotator cuff repairs, theechniques fall into 2 broad categories: transosseousuture repairs and suture anchor repairs. All of theescribed techniques are done arthroscopically or inn arthroscopically assisted manner to avoid posteriorissections of the knee.Although West et al.27 were the first investigators to

escribe a transosseous repair for the lateral MRT,ater techniques have been described to repair theedial MRT. Raustol et al.20 described an arthro-

FIGURE 3. Coronal fat-saturatedT2-weighted magnetic reso-nance images, (A) posteriorlyand (B) at the level of theMCL, in an adolescent afteracute trauma show meniscalroot avulsion (arrow in A) andborderline extrusion of the me-dial meniscal body in associa-tion with MCL tear (arrow inB); the absence of chondralwear, making this individual agood candidate for meniscalroot repair, should be noted(Fig 4).

copic technique using an accessory posteromedial

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1029MENISCAL ROOT TEARS

ortal placed at a high angle to facilitate suture pas-age using 2 Beath pins. These were passed throughhe medial root, creating a mattress stitch of No. 1olydioxanone suture, and exited anterolaterally,here they were tied over a bone bridge. Kim et al.18

escribed passing two No. 2 Ethibond sutures (Ethi-on, Somerville, NJ) using a Caspari passer with ahuttle through the medial meniscal root and thenying them over a screw and washer anteromediallyfter retrieving them through a 5-mm tunnel drilledsing an ACL guide. Petersen and Zantop22 describedsimilar technique for the lateral meniscus using anCL guide, overdrilling with a 4.5-mm drill and tying

he sutures over a button.Whereas most authors describe passing the arthro-

cope under the PCL to visualize the posterior root ofhe medial meniscus, Ahn et al.14 described the use ofposterior trans-septal portal to facilitate visualizationoming from posterolaterally with the arthroscope.heir technique describes placing the ACL guide

hrough the posteromedial portal and using a 2.9-mmannulated drill from anteromedial to pass the sutureshat are then subsequently post tied. In a follow-uprticle, they described using a double-row techniqueo theoretically maximize fixation and healing poten-ial.15 Marzo and Kumar19 described a similar trans-sseous technique; however, it did not use posteriorccessory portals, instead facilitating suture passageith the Scorpion device (Arthrex, Naples, FL). Theyrilled a 7-mm tunnel using an ACL guide and tiedheir sutures over a washer.

Arthroscopic fixation of meniscal root avulsion byse of a suture anchor construct was originally de-cribed by the senior author (G.S.D.) in the article byngelsohn et al.17 (Fig 4). The root avulsions were in

he setting of 2 multiple ligament–injured knees, andhus significant pathologic ligamentous laxity aided inisualization and repair. An accessory posteromedialortal was used for placement of the bioabsorbableorkscrew suture anchors (Arthrex), and then mat-

ress suture passage was accomplished by use of theiper device (Arthrex). Recently, Choi et al.16 de-

cribed a similar technique using a double-loadedetal anchor and accomplished suture passage using a

uture hook and a polydioxanone shuttle suture. Theheoretic advantages of suture anchor repairs are thathey avoid the need for tunnels that could interfereuring concomitant ligament reconstruction, and theyvoid the need for distal fixation that places the su-ures at risk for failure due to abrasion.

There have been limited clinical studies following

RTs and repairs. Engelsohn et al.17 confirmed me- f

iscal root healing after suture anchor repair duringecond-look arthroscopy performed for lysis of adhe-ions at 6 months postoperatively in 1 patient andbtained MRI confirmation at 9 months postopera-ively in the other patient. Ahn et al.21 recently con-rmed complete healing of posterior lateral MRT re-air through second-look arthroscopy in 8 patients at aean of 20 months. Griffith et al.30 presented the

ongest follow-up, with MRI performed at 3 yearsostoperatively that confirmed anatomic healing of theepaired posterior root avulsion fracture using a trans-sseous technique.

ILLUSTRATIVE CASE

A 15-year-old boy was riding his bike when he wastruck by a motor vehicle. He had a grade 3 concus-ion and an isolated left knee dislocation that sponta-eously reduced in the field. He was treated accordingo standard trauma protocols. The neurovascular struc-ures of the limb were intact, but the knee was grosslynstable to anterior, posterior, and valgus testing onlinical examination. An MRI scan of the left knee,btained 1 week after injury, showed an ACL tibialvulsion, a midsubstance PCL tear, and an MCL tibialvulsion. In addition, a posterior horn medial MRTas identified. Given the patient’s age and traumatic

njury pattern, he was deemed a good candidate forurgery.

Seventeen days from the initial injury, the patientnderwent surgery. An arthroscopic ACL repair withutures placed through drill holes and tied over autton was used to address the ACL avulsion. Anrthroscopic all-inside Achilles allograft PCL Retro-onstruction (Arthrex) was performed to address theCL rupture. An open MCL repair with suture an-hors was performed to address the MCL avulsion.

For the meniscal root repair (Fig 4, Video 1 [onlinenly, available at www.arthroscopyjournal.org]), anrthroscopic suture anchor technique (4.5-mm poly-ther-etherketone Corkscrew anchor, double loadedith No. 2 FiberWire [Arthrex]) was performed.iven the pathologic laxity encountered at the time of

urgery, the accessory posteromedial portal that wassed was placed in routine fashion and afforded us theppropriate angle for anchor insertion. (It should beoted that in ligamentously stable knees, a high pos-eromedial portal is usually necessary to accomplishppropriate anchor placement.) Next, the insertion siteas roughened with an arthroscopic rasp and shaver.nce the anchor was placed, a Scorpion suture passer

rom the anteromedial portal was used to pass the No.

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1030 J. H. KOENIG ET AL.

IGURE 4. Illustrative case of MRT suture anchor repair (also shown in Video 1, online only, available at www.arthroscopyjournal.org): Arthroscopiciews of medial meniscus in left knee of an adolescent boy 17 days after traumatic multiligamentous knee injury (ACL-PCL-MCL, medial MRT). For allmages (A-F), the view is from the anterolateral viewing portal and the probe is in the anteromedial working portal. (A) Anterolateral view of middle onehird of medial meniscus (right-facing arrow) showing the tibia (left-facing arrow) and amount of extrusion (gap between arrows). This image correlatesxactly with Fig 3B, although the extrusion is somewhat more pronounced given the distension from the arthroscopy. (B) Critical view of medial MRThowing posterior horn (probe), meniscal root (asterisk), and tear junction (arrow). (C) Same critical view with accessory posteromedial portal in place andRT debrided. The meniscal root (asterisk) and tear junction (arrow) are clearly visible. (D) Same view now showing 4.5-mm polyether-etherketone

orkscrew anchor (Arthrex), double loaded with No. 2 FiberWire (Arthrex), in place. (E) Same view of medial meniscus through anterolateral portal afternal MRT repair. (F) Similar view still through anterolateral portal but with scope in notch looking down on root repair.

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1031MENISCAL ROOT TEARS

FiberWire, in mattress fashion, through the avulsedeniscal root. Arthroscopic knot tying was performed

n standard fashion to repair the root back to its formernsertion, and the repair was found stable to probing.he patient’s knee was immobilized with limitedeight bearing for 4 to 6 weeks. Passive range-of-otion exercises were begun at 2 weeks with isometric

uadriceps contractions in extension. After 6 weeks,eight bearing was progressed and closed-chain

trengthening was begun.

CONCLUSIONS AND FUTURECONSIDERATIONS

MRTs are unique injuries with unique biomechani-al consequences in terms of load bearing and subse-uent progression of arthritis (Table 1). There appearso be a group of patients who have acute traumatic

RTs with extrusion and minimal compartmental dis-ase who are amenable to repair, theoretically restor-ng the critical biomechanics of the meniscus. Surgicaltrategies focused on MRT have been developed andre currently being refined. However, at present, therere few long-term data to determine the outcomes ofur interventions, and future research is necessary inhis field. In addition, although recent research hashed light on the anatomy and consequences of medialRT, more research is needed to determine the causes

nd biomechanical results of lateral MRT. Althoughhey have different anatomic insertions, treatmentechniques associated with medial MRTs are applica-le to those of lateral MRTs.

REFERENCES

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TABLE 1. Keys to Success When Treating MRT

nderstanding unique insertional anatomy of meniscal roots andtheir relation to other structures

eviewing biomechanical consequences of medial MRTsing MRI in diagnosis and discernment of MRT v radial tearof paracentral meniscal horn: only the root is amenable torepair

dentifying ideal candidates for surgical repair: young patientswith clear traumatic MRT and preserved chondral surfaces

hoosing most appropriate arthroscopic technique using sutureanchors or bone tunnels

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