Meniscus – Anatomic, Biologic, and

Biomechanical Factors That Affect

Tear Prognosis

Jeremy M. Burnham, MDUPMC Sports Medicine

July 22, 2017 – AOSSM Annual Meeting

What Affects Prognosis?

McDermott, Amis JBJS (Br) 2006

• 75% decrease in contact area

• 235% increase in peak pressures

What Affects Prognosis?

• Tear Factors

– Location

– Vascular Zone

– Tear Size

– Tear Pattern

• Injury

– Acute vs. Chronic

– Concomitant Injuries

– Alignment & Stability

• Patient

– Age, BMI, Activity

McDermott, Amis JBJS (Br) 2006

Meniscus Vascularity

• Entire meniscus is vascular at birth,

but inner 1/3 avascular by nine months

• In adults, outer 10-30% is vascular

• Formation of a clot is essential for

healing, and tears in the red-red zone

(outer 1/3) are most likely to heal

• Fibrin clots, abrading synovium

adjacent to repair, and “freshening up”

the tear site are ways to improve

healing

Meniscus Vascularity

Patient Age

• Older patients have less cellularity and decreased healing

response

– Retears more frequent in patients >30 (Eggli et al. AJSM 1995)

– Older patients had longer time to failure (Bach et al. J Knee Surg

2005)

• Mixed Clinical Results

– No RCTs

– Selection bias (most surgeons won’t repair degenerative tears)

Older Patients, Chronic Tears

• RCT, Level I Evidence

• 102 pts with knee pain and degenerative tear of the PH

of the medial meniscus

• Excluded: trauma, ligament deficiency, systemic

arthritis, osteonecrosis

Older Patients, Chronic Tears

Older Patients, Chronic Tears

• Average duration of symptoms prior to treatment ~8 mths

– Nonop: Medicine, PT 3x/wk for 3 wks, HEP for 8 wks

– Operative: Partial menisectomy

• Pain improved more quickly in operative group, but no difference

at 2 years

• No differences in satisfaction, Lysholm, or OA progression at 2

years

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Chronic, Complex Pattern, Older Patients

Acute Tears, Young or Old Patients

• Cohort study

• 339 meniscus repairs (136 <40y, 45 >40y)

• 4.4 to 12% lost to follow up

• Minimum follow-up 10 years

• All inside-out repairs

• No postoperative PRO difference (Lysholm, WOMAC, SF-12)

between groups

Acute Tears, Young or Old Patients

• Patients <40 and >40 improved similarly after meniscus repair

• Failure rate at minimum of 10 years ~5% in both groups

Meniscus Tear Pattern

• Tear Pattern

– More reparable tears found in

unstable as compared to stable

knees

– Double longitudinal and complex

tears have low rate of healing

– Horizontal cleavage tears may

be asymptomatic

– Partial radial tears in avascular

region may require only

debridement

– Complete radial tears and root

tears are equivalent to total

meniscectomy

(Starke et al. 2009; Image from Meniscus Tears, Noyes & Barber-Westin)

Radial Tear

Radial Tear

Tear Pattern - Meniscal Root Tears

• 9 fresh frozen cadaver knees

• Axial load of 1000N at 0, 30, 60, and 90 degrees

• Fuji pressure sensitive film

Meniscal Root Tears

Meniscal Root Tears

Radial Tear Near Root

Radial Tear Near Root

• 6 fresh frozen knees

• 1000 N Load at 0, 30, 45, 60, and 90 degrees

• Intact, Root avulsion, radial tear, and repair of each

• Tekscan sensors

Radial Tear Near Root

Radial Tear Near Root

Malalignment

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Concomitant Injury

• Concomitant Injury

– Meniscal repairs tend to heal better in association

with ACL reconstruction

• Stabilization of the knee decreases microtrauma

• Marrow elements introduced into the joint

Concomitant

Failure to Address Instability

27Trojani, KSSTA, 2011

Meniscus Repair - Outcomes

• 2012 systematic review of 13 studies (minimum 5 year follow-up)

• Pooled failure rate was 23% (or survival was 77%)

• Medial meniscus failure rate (24%) greater than lateral meniscus (20%)

• Failure rate similar between non weight bearing (25.7%) and partial

weight bearing (21.7%)

• Failure rate similar between immobilization (23.7%) and early motion

(22.7%)

Meniscus Repair - Outcomes

• Limitations:

– Variety of tear patterns and locations

– Variable population

– Missing information

Meniscus Repair - Outcomes

• 2012 systematic review of 19 studies

• 311 relevant patients (139 inside-out, 172 all inside)

• Pooled failure rate 17% for inside-out, 19% for all-inside

• Lysholm 88 for inside-out, 90 for all-inside (MCID 10)

• No difference in Tegner activity levels

Meniscus Repair - Outcomes

• Shorter operative time for all-inside (not quantifed)

• 9% nerve irritation in inside out versus 2% for all-inside

• Unable to quantify differences in chondral damage or scuffing

• Heterogenous studies

• No cost analysis

Acute Tears, Young or Old Patients

• Patients <40 and >40 improved similarly after meniscus repair

• Failure rate at minimum of 10 years ~5% in both groups

Meniscus Repair

• 293 Patients Patients <20 years old, single institution

• 129 primary repairs, 149 meniscectomies, 46 discoid saucerizations

• Mean follow-up 40 months (19-62 months)

• 13% revision rate

– Primary Repair Group = 18% Revision Rate

– Bucket Handle = 47% Revision Rate

– 76% were acute reinjury, 77% within one year

Repair vs. Meniscectomy

If 10% of meniscectomies changed

to repairs, would save $43 million

• Repairs may fail

more, but still more

cost effective

• Improves Outcomes

• Decreases overall

costs of treatment

Summary – Prognostic Indicators

Summary – Prognostic Indicators

• Success rate of repairs reported between 76-94%

• Repair more cost-effective

• Tear-specific

– Posterior radial tears = total menisectomy

– bucket handle = 47% failure of repair

• Patient-specific

– Older patients have less healing response, but can be less

functionally demanding

– Studies are mixed, results probably equivalent

• Injury-specific

– Chronic, degenerative tears = nonop

– ACL recon = improved healing, more repairable patterns

Thank You

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