1. Meniscal Tears and Their Treatment
Robert S. Fawcett M.D., M.S.
York Hospital Family Medicine Residency
York, PA

2. Objectives
Discuss important points in history, physical and testing that lead to a diagnosis of damaged meniscus
Understand the short and long term outcomes of meniscectomy
Discuss the benefits and implications of surgical vs. conservative management of meniscal tear

3. Epidemiology
Overall incidence unknown, but surgical incidence is per 100,000 per year
Most common orthopedic surgical procedure
1/3 of meniscal tears are sports-related (most of the rest from MVAs)
1/3 of meniscal tears associated with ACL injury

4. The medial meniscus is somewhat semicircular in appearance
The medial meniscus is somewhat semicircular in appearance. It is approximately 3.5 cm in length in the anteroposterior dimension and considerably wider posteriorly than it is anteriorly. Its radius of curvature varies, giving it greater length in the sagittal plane than in the coronal plane. The anterior horn is attached to the tibial plateau in the area of the anterior intercondylar fossa, 6 to 7 mm in front of the ACL insertion. An intermeniscal, or “transverse,” ligament is present in 64% of individuals; this connects the anterior horn (posterior fibers) of the medial meniscus and the anterior horn (anterior fibers) of the lateral meniscus.[65] The posterior horn attaches to the posterior intercondylar fossa between the attachments of the lateral meniscus and the posterior cruciate ligament (PCL). The medial meniscus is continuously attached to the joint capsule along the entire periphery. The coronary ligament represents the tibial portion of this capsular attachment. At its midpoint, the medial meniscus is firmly attached to the femur and tibia through a robust thickening in the capsule known as the deep medial collateral ligament.
Lateral Meniscus
The lateral meniscus covers a larger portion of the tibial surface than does the medial meniscus. Its radius of curvature remains fairly constant, giving the lateral meniscus an almost circular appearance. The anterior horn is attached anterior to the intercondylar eminence, just posterior and lateral to the ACL attachment with which it partially blends. The posterior horn attaches posterior to the intercondylar eminence, just in front of the posterior end of the medial meniscus. In 50% of individuals, anterior fibers of the posterior enthesis extend to the lateral aspect of the medial femoral condyle, forming the anterior meniscofemoral ligament (ligament of Humphry).[55][65] In 76% of cases, the posterior fibers of the posterior horn cross posterior to the PCL and attach to the intercondylar fossa of the medial femoral condyle, forming the posterior meniscofemoral ligament (ligament of Wrisberg).[55] The lateral meniscus has only a loose peripheral attachment to the capsule, which is interrupted by the popliteus tendon. Lateral meniscal variants, including the most recognized discoid meniscus, have a reported prevalence as high as 16.6% (see “Special Considerations”).[43]
--DeLee and DeLee

5. Structure of the Meniscus
Medial is semicircular
Moves 2-5 mm through full ROM
Lack of motion may promote tears
Fibers from the deep medial collateral
Lateral almost a complete circle
Moves ~1 cm through full ROM
Both made of fibrocartilage
75% circumferential type 1 collagen fibers
25% radial fibers
Blood supply thru plexus from superior and inferior geniculate arteries.
Anterior horn of med meniscus attaches ant to fibers of ACL
Posterior horn is wider and attaches just posterior to fibers of ACL
Laterally, mm is anchored to medial collateral fibers.
64% of people have transverse lig connecting med and lat menisci anteriorly
Med meniscus attached to joint capsule throughout its circumference, tightly at med collateral.
Ant and post horns of semicircular lat meniscus attach lat to lat fibers of ACL.
Lat men more loosely attached than medial.
Ligaments of Humphreys and Wrisberg attach from posterior portion of lat men, run adjacent to post CL, and attach to fem cond.

6. Tears and Zones

7. Structure of the Menisci
Vascular supply good in the most peripheral 20% of the fibers
Supplied by the geniculate arteries
Inner 1/3 of the ring is avascular
Relatively thin
Nourished through synovial fluid
Middle 1/3 of the ring is combination

8. Function of the Menisci
Distribute load across the knee joint
2-4x body weight during walking
6-8x body weight during running
Axial compression is converted to “hoop stress”, or circumferential elongation in the meniscus
Lateral meniscus distributes more load than medial meniscus, which contributes to greater degeneration if disrupted
Menisci deepen the socket of the tibial plateau, contributing to stability of knee

9. Function of the Menisci
Wedge shape limits translation of femur on tibial plateau
Menisci forced posteriorly in flexion, anteriorly in extension of the knee
Menisci reduce stresses on the ACL
Menisci force synovial fluid into articular cartilage (helping to nourish the white zone) during compression.

10. Pathophysiology
In acute knee injuries with ACL intact, medial meniscal injury is 5 times more likely than lateral
In acute knee injuries with ACL ruptured, lateral meniscus more likely to be involved
If ACL is previously disrupted, lateral meniscal injury is more likely than medial
In repetitive deep squatting, medial meniscus most likely to be injured (20:1)
Medial meniscus is tethered to joint capsule and is less stable
Lat more likely than medial with ACL due to shift of lateral femoral condyle

11. History: the Key to Diagnosis
Twisting on planted foot
Inertial forces or external forces
Acute effusion in acute injury
Waxing and waning course with pain and effusion intermittently in chronic injury
The older the patient, the less likely that history will be revealing
More likely to occur with trivial trauma
Difficult to distinguish from DJD

12. }80% }95% Physical Exam * Finding/Test Sensitivity Specificity
Joint Line Tenderness
71%
27%
McMurray
58.5%
93.4%
Apley
58%
80%
Thessaly 5o
Thessaly 20o
66%Me, 81%La
89%Me, 92%La
96%Me, 91%La
97%Me, 96%La
MRI
75-87%
87-93%
}80%
}95% *
Clinical examination is the primary diagnostic tool for intra-articular and meniscal injuries. The most common findings, similar to those of adults, are joint-line tenderness and effusion [7] [31] . Because of the diversity of pathology and the difficulty of examination in children in an acute setting, the diagnostic accuracy of clinical exam for meniscus tear has been shown to be as low as 29% to 59% in series with multiple examiners [5] [32] . In children, anteromedial or anterolateral joint-line pain may be caused by patellofemoral pain, patellar instability, iliotibial band friction, osteochondritis dissecans, or other lesions. Sensitivity of McMurray and Apley tests is estimated to be 58% with even lower specificity [5] . Two recent studies, by examiners with significant pediatric sports medicine experience, showed the diagnostic accuracy of clinical exams to be 86.3% and 93.5% overall [32] [33] . When medial meniscus tears were looked at alone, sensitivity and specificity of clinical exams were 62.1% and 80.7%, respectively [32] . Sensitivity and specificity for lateral meniscal tears were 50% and 89.2%, respectively [32] .
Comparison of knee magnetic resonance imaging findings in patients referred by orthopaedic surgeons versus nonorthopaedic practitioners . 
Arthroscopy: The Journal of Arthroscopic & Related Surgery , Volume 18 , Issue 2 , Pages
P . Sherman , B . Penrod , M . Lane , J . Ward
Abstract
Purpose: To compare the percentages of normal magnetic resonance imaging (MRI) examination results and clinically significant knee abnormalities in patients referred for MRI of the knee by orthopaedic surgery residents and staff with those of patients referred by nonorthopaedic practitioners. Type of Study: Retrospective review of MRI findings. Methods: MRI reports of 754 patients (454 men and 300 women) were retrospectively reviewed; 373 patients were referred from the Department of Orthopaedic Surgery and 381 patients were referred from nonorthopaedic practitioners. The number of normal examination results, meniscal and ligament tears, chondral abnormalities, and Baker’s cysts was tabulated and analyzed using a χ-square injury analysis. Results: The rate of normal results for nonorthopaedic practitioners was 33.9% (129 of 381) compared with 15.3% (57 of 373) for orthopaedic surgeons (P < .001). Nonorthopaedic surgeons referred 69.4% (129 of 186) of the patients who had normal examination results. The positive finding for a lateral meniscus tear was 29.2% (109 of 373) for orthopaedic surgeons compared with 19.1% (73 of 381) for nonorthopaedic practitioners, which was statistically significant (P = .002) in regard to the distribution of injuries. No difference was found in other abnormalities assessed. Conclusions: Patients referred by nonorthopaedic practitioners had significantly more normal knee MRI examination results than did those referred by orthopaedic surgeons.
*This test has not yet undergone external validation studies

13. Thessaly Test? Done with pt standing, first on normal leg
Flex knee 5 degrees, rotate body on fixed leg back and forth 3 times, holding examiner’s hands for stability
Flex further to 20 degrees and repeat
Repeat on affected leg
Positive is pain at joint line or feeling of locking or catching

14. Value of MRI as Diagnostic Tool
Studies do NOT prove it superior to composite clinical exam
Many false positives appear
MRI has high NEGATIVE predictive value
Sensitivity and specificity keep getting better as technology improves
How will MRI result change treatment?
No surgeon would touch a knee without one
Helps with planning procedure
Tears are seen as high-grade signal areas within the substance of the meniscus. Radiologists user grading system to delineate these signal changes, with grade 0 being normal meniscus, grade 1 and 2 high signal intrameniscal areas that do not abut the free meniscal edge, and grade 3 high signal area that tracks to the edge of the meniscus. Grade 3 changes are the only changes consistent with clinically significant meniscal tear and, for this reason, care must be used when interpreting MRI images and reports. Care must also be used when interpreting signal changes in a patient who has had previous meniscal surgery, as MRIis often unreliable in these cases.

15. Bucket Handle Tear

16. Oblique Tear

17. Treatment Options Total meniscectomy Partial meniscectomy
Meniscal repair
Inside out
Outside in
All inside
Conservative (No operative intervention)

18. Consequences of Meniscectomy
As early as 1948 Fairbanks noted increased osteophyte formation and femoral cartilage deterioration in meniscectomized knees
Total meniscectomy remained a common procedure until the 1980’s
In medial meniscectomy, load bearing surfaces are halved, doubling stress on tibial plateau
If 15-30% of meniscus is removed, forces between tibia and femur increase up to 350%
It is now appreciated that menisci serve many functions, including increasing contact area and congruency of the femoral-tibial articulation. The menisci load-share and reduce contact stresses across the joint. It is estimated that menisci transmit up to 50% to 70% of the load in extension and 85% in 90° of flexion [21] . Baratz and Fu showed that, following total menisectomy, the contact area decreased by 75% and contact stresses increased 235% [22] . They also documented deleterious effects of partial menisectomy, demonstrating that contact stresses increased in proportion to the amount of meniscus removed. Excision of narrow bucket-handle tears of the medial meniscus increased contact stress by 65%, and 75% resection of the posterior horn increased contact stresses equivalently to that of total menisectomy [22] . Repair of meniscal tears reduced contact stresses to normal. Other studies corroborate the mechanical importance of the meniscus [

19. Meniscus Repair Used in longitudinal tears
Many fixation devises, none better than sutures, though some are faster
Outside in, inside out, and all inside technique
Inside out most useful in posterior or lateral tears.
Outside in most useful for anterior tears.
All inside techniques involve specialized darts or anchors or arrows with methods of insertion and are not as secure

20. Criteria for Meniscal Repair vs. Partial Meniscectomy
Criterion
Repair
Ptl. Meniscectomy
Distance from rim
<3mm
>3mm
Mobility of fragment
Stable
Mobile
Age of injury
Recent
Old
Ret. To Play
Later
Sooner
Age of patient
Younger
Older
Some small, nondisplaced meniscal tears in the outer vascular region may heal spontaneously or become asymptomatic [5] [17] [18] . Nonoperative treatment consists of rehabilitation of the injured knee with the avoidance of pivoting and sports for 12 weeks.
The majority of meniscal tears in pediatric patients are large and require surgical treatment [5] [17] [18] . Arthroscopic management is standard with partial menisectomy (Fig. 2) or meniscal repair using outside-in, all inside (Fig. 3) , or inside-out techniques (Fig. 4) [17] [18] [36] . We believe that, in children and adolescents, meniscal repair should be attempted, instead of partial menisectomy, for middle third and outer third meniscal tears because of the theoretical greater healing potential at this age. Long life span and poor results of total and near-total menisectomy, and lack of longer-term results of partial menisectomy, encourage meniscal salvage attempts. Inside-out techniques are useful for anterior horn medial or lateral meniscal tears (Fig. 4) . Meniscal-body and posterior-horn tears are repaired b the traditional inside-out repair with vertical or horizontal sutures. Zone-specific cannulas can direct the flexible suture needles to appropriate positions to avoid neurovascular structures. We routinely make an incision posteromedially or posterolaterally to identify and retrieve the suture needles and tie the sutures at the joint capsule, protecting the saphenous nerve and vein medially and the peroneal nerve laterally. Newer all-inside devices have facilitated meniscal repair in adults (Fig. 3) . Reports of articular cartilage damage from heads of bioabsorbable arrows and darts exist [17] [18] and many of the devices extend too far through the capsule in a pediatric knee, with potential for pain and neurovascular injury. We prefer more recent all-inside low-profile suture devices for posterior horn tears in adolescent knees. For smaller tears without substantial displacement, we use these devices alone. For larger tears with displacement, eg, bucket-handle tears, we use them in a hybrid manner with inside-out sutures (Fig. 5) . Regardless of instrumentation used, surgical principles are important to maximize meniscal healing and include preparation of the repair site using abrasion or trephination, anatomic reduction of the meniscal tear, adequate strength and durability of repair devices, and protected knee mobilization.

21. Meniscus Repair--Recovery
Pts must wear brace with pwb for 2 weeks
Sedentary workers back to work in 1 week
Laborers back in 6-8 weeks
Athletes back in weeks
76% “excellent” results after 10 years* *

22. Partial Meniscectomy Done when tear involves interior 70%
May be done when athlete wants to resume activity ASAP
Done with mobile fragments
10-35 minute arthroscopic procedure under regional or general anesthetic
Mobile areas removed
Edges contoured to “prevent further tears”
Immediate partial weight bearing allowed
Crutches for 1-2 days

23. Partial Meniscectomy--Recovery
Sedentary workers back to work in 1 week
Laborers back in 2-4 weeks
Athletes back in 2-6 weeks
88% “excellent” results at 15 years*
*Burks RT, Metcalf MW, Metcalf RW; 15 yr f/u of arthroscopic partial meniscectomy; Arthroscopy 1997; 13:673-9.

24. Conservative Therapy
Not an option if knee locked, fragment not reduced
Symptom relief with post-exercise RICE
Symptom relief with NSAIDS, immobilization
Physical therapy focusing on closed chain exercise of quadriceps and hamstrings
Failure includes recurrent effusion, recurrent locking or pain that interferes with ADLs
No randomized trials

25. Conservative Study Result
Retrospective review of 3612 arthroscopies
Identified 80 “stable” tears (<3mm movement) for whom nothing was done
70 were longitudinal, 10 were radial
Only 6 needed subsequent surgery, 4 of which had had additional trauma
32 patients had “second look” surgery
17/22 longit. tears, 0/6 radial tears healed completely
Weiss CB, Lundberg M, DeHaven KD, Gillquist J; Non-operative treatment of meniscal tears. JBJS A(6):

26. Conservative Study Results
“Stable” tears at ACL reconstruction left to heal and 2nd look removing ACL hardware
Lateral: 74% healed, 6% incompletely healed, 14% unhealed
Medial: 56% healed, 6% incompletely healed, 24% unhealed
Healing rate was “length dependent”
Yagashita et al. Am J Spts Med (8):1953

27. Conservative Study Results
32 patients
30 lateral and 10 medial meniscal tears along with 25 ACL tears and 7 PCL tears
Arthroscoped initially with repeat at 3 mo.
Lateral meniscus: 69% completely healed and 18% incompletely healed
Medial meniscus: 58% completely healed and 0% incompletely healed
Ihara H, Miwa M, Takayanagi K, Nakayama A. Clin Orthop Relat Res Oct;(307):

28. Ihara: Results Without Surgery
Injury
Results at 2nd Look
Lat Meniscus
69% healed completely,
18% healed partially
Medial Meniscus
58% healed completely
0% healed partially
Ant. Cruc.
Ligment
80% healed “satisfactorily”
Post Cruc.
Ligament
3/7 (40%) healed “satisfactorily”

29. Cochrane Review 2002 No evidence for comparing surgery to no treatment
Partial is better than total meniscectomy:
Less operative time
Enhanced recovery rate
Improved long term stability
Arthroscopic is better than open meniscectomy
Quicker recovery post-op
No long term advantages have been shown
A Cochrane library review evaluated "the effects of common surgical interventions in the treatment of meniscal injuries of the knee. The four comparisons under test were: a) surgery versus conservative treatment, b) partial versus total meniscectomy, c) excision versus repair of meniscal tears, d) surgical access, in particular arthroscopic versus open.
Three trials, involving 260 patients, which addressed two (partial versus total meniscectomy; surgical access) comparisons were included. Partial meniscectomy may allow a slightly enhanced recovery rate as well as a potentially improved overall functional outcome including better knee stability in the long term. It is probably associated with a shorter operating time with no apparent difference in early complications or re-operation between partial and total meniscectomy. The long-term advantage of partial meniscectomy indicated by the absence of symptoms (symptoms or further operation at six years or over: 14/98 versus 22/94; Peto odds ratio 0.55, 95% confidence interval 0.27 to 1.14) or radiographical outcome was not established. The results available from the only trial comparing arthroscopic with open meniscectomy were very limited in terms of patient numbers and length of follow-up. However it is likely that partial meniscectomy via arthroscopy is associated with shorter operating times and a quicker recovery.
Reviewers' conclusions: The lack of randomised trials means that no conclusions can be drawn on the issue of surgical versus non-surgical treatment of meniscal injuries, nor meniscal tear repair versus excision. In randomised trials so far reported, there is no evidence of difference in radiological or long term clinical outcomes between arthroscopic and open meniscal surgery, or between total and partial meniscectomy. Partial meniscectomy seems preferable to the total removal of the meniscus in terms of recovery and overall functional outcome in the short term." (1)

30. Summary: What We Know
The meniscus, torn or intact, helps to stabilize and dissipate axial force in the knee
Degenerative changes develop more frequently in meniscectomized (total or partial) than in normal knees (Williams, others)
When meniscal repairs fail, pts are often engaging in the same activity as initial injury
Longitudinal tears heal more readily than radial tears and simple or bucket handle tears heal more readily than complex ones

31. Summary: What We Know
Peripheral tears (in the vascularized area) heal more readily than central tears (Noyes, Krych)
Meniscal tears are accompanied by ligament tears in many cases
Repairing both meniscus and ligaments (when both injured) improves outcomes (Noyes)
Ligamentous pathology with meniscal tears makes degenerative changes more likely

32. What We Know
Younger pts do better with meniscal repair than older patients (Mintzer)
Less surgery is better than more surgery
Arthroscopy better than open
Partial better than complete meniscectomy (Cochrane)

33. What We Don’t Know Whether no surgery is better than less surgery
Whether operating on stable radial tears improves outcomes
How to tell without surgery that conservative treatment is a reasonable option
Whether and how long to immobilize the acute tear
If a repair is undertaken, what timing and type of repair has the best outcomes
If no repair is done, whether and when to do a “second look”

34. Bibliography
Karachalios T, Hantes M, Zibis AH, et al. Diagnostic accuracy of a new clinical test (the Thessaly test) for early detection of meniscal tears. J Bone Joint Surg 2005;87:955–62.
Krych AJ, McIntosh AL, Voll, Michael AE, Stuart J, Dahm DL. Arthroscopic Repair of Isolated Meniscal Tears in Patients 18 Years and Younger. Am. J. Sports Med. 2008; 36; 1283 originally published online Mar 4, 2008.
Manson TT, Cosgarea AJ. Meniscal injuries in active patients. Advanced Studies in Medicine November-December 2004, 4(10):
Muellner T, Weinstabl R, Shabus R, Vecsei V, Kainberger F; The diagnosis of meniscal tears in athletes: a comparison of clinical and magnetic resonance imaging investigations. Am J Sports Med 1997; 25:7-12.
Ihara H, Miwa M, Takayanagi K, Nakayama A. Clin Orthop Relat Res (307):
Johnson MJ, et al. (1999). Isolated arthroscopic meniscal repair: A long-term outcome study (more than 10 years). American Journal of Sports Medicine, 27(4): 44–49.
Mintzer CM, Richmond JC, Taylor J. Meniscal repair in the young athlete. Am J Sports Med 1998;26:630-3.
Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscal tears extending into the avascular zone in patients younger than twenty years of age. Am J Sports Med 2002;30:
Weiss CB et al. Non-operative treatment of meniscal tears. JBJS A(6):
Howell JR Handoll HHG. Surgical treatment for meniscal injuries of the knee in adults (Cochrane Review). In: The Cochrane Library, Issue 3, Oxford: Update Software.
Williams RJ et.al. MRI evaluation of isolated arthroscopic partial meniscectomy patients at a minimum five year follow-up. HSSJ :35-43.