1. Meniscus Injuries
Ian Rice MD

2. How far we haven’t come
“…It is, however, a clinical fact that one of the semilunar cartilage, usually the internal one, does occasionally become loosened from its attachments; and, in consequence, this body is liable to be displaced either forwards or backwards, and so to interfere with the proper movements of the knee-joint…”

3. Epidemiology
Among most common injuries seen in orthopedic practice
61 cases per 100,000 per year
Arthroscopic partial menisectomy one of the most common orthopedic procedures

4. Pathoanatomy Overview
Crescent shaped and have triangular cross section
Fibers have circumferential orientation
Anterior and posterior root attachments prevent extrusion
Lateral covers 84% of the condylar surface, 12mm wide, 3-5mm thick
Medial covers 64%, 10mm wide, 3-5mm thick

5. Pathoanatomy Vascularity Genicular arteries 50% vascularized at birth
10-25% in adults
Makes healing very difficult
3 vascular zones
Red-red
Red-white
White-white

6. Collagen Organization
Pathoanatomy
Collagen Organization
Circumferential fibers
Radial Fibers
Fine superficial layer around outside
O’Connor’s textbook of arthroscopic surgery, Philadelphia, 1984.

7. Meniscal function Load Sharing Increases congruity Provides stability
Increases contact area between femur and tibia
Decreases contact stress on articular cartilage
Increases congruity
Provides stability
Aids in lubrication

8. Biomechanics
In extension, 50% of the load is absorbed
At 90 flexion, 90% load-sharing
Beyond 90, forces predominate through posterior horns

9. Meniscal excursion with knee flexion
11.2 mm excursion of lateral meniscus
5.1 mm excursion of medial meniscus
Capsule
Deep MCL
Coronary ligament
Thompson (1991) studied meniscal motion with 3-dimensional MRI and cinematic MRI. Medial meniscal excursion was approximately 5.1 mm, and lateral meniscal excursion, 11.2 mm. The posterior horn excursion has been noted to be less than that of the anterior horn, both medially and laterally. The posterior oblique ligament is firmly attached to the posterior medial meniscus, thereby limiting its displacement and rotation.
Thompson WO, Thaete FL, Fu FH, Dye FF. Tibial meniscal dynamics using three dimensional reconstruction of magnetic resonance images. Am J Sports Med. 1991;19:

10. Biomechanics
Complete removal of meniscus results in 2-3X increase in contact stress
Removal of inner 1/3 = 10% reduction in contact area and 65% increase in stress
Increase loss of meniscal tissue = increase contact stress
Medial meniscal root tears have pressures similar to complete meniscectomy

11. Evaluation
History
Twisting injury with change in direction in younger patients
Squatting or falling in older patients
Acute tear usually has insidious swelling
Joint line location
Mechanical complaints

12. Physical Exam Small effusion Joint Line Tenderness McMurray Apley
Thessaly
ROM generally normal
Bucket handle block
Tight due to effusion

13. McMurray

14. McMurray

15. Apley’s Compression Test

16. Thessaly Test

17. Imaging Plain films to assess for bony injury and OA
MRI is the gold standard of diagnosis

18. Longitudinal Vertical Tears
Typically seen in younger patients
High association with ACL tears
90% of LVT in MM and 83% in LM are associated with ACL tears

21. Bucket Handle Tears
This is a LVT with central margination
Most frequent type of displaced tear
Double PCL
Double Anterior Horn
Absent Bow

23. Horizontal Tears
Involves the free edge and propagates peripherally
Usually degenerative
Older patients

26. Radial Tears
Also involve free edge, but path is perpendicular to long axis
Drastically affect ability to resist hoop stresses
Deeper the tear, the more drastic the biomechanical consequences

27. Radial Tears

28. Radial Tear

29. Parrot Beak Tears AKA vertical flap tear Starts as a radial tear
Propagates as a longitudinal

30. Parrot Beak Tear

31. Root Tears

32. Treatment Non-surgical
Stable, longitudinal <10mm with <3-5mm displacement
Degenerative tears with concomitant OA
<3mm radial tears
Stable partial tears

33. Meniscectomy Indications Radial Flap Horizontal Complex
White-white tears

34. Meniscectomy Goal is to debride tear and leave stable rim
Preservation is ideal
80% satisfactory function at 5 yrs
Lateral debridement = faster degeneration

35. Meniscectomy Predictors of Positive Result < 40yo Normal alignment
Minimal arthritis at initial scope
Single fragment tear

36. Surgical Repair Relative Contraindications Advanced OA Complex tears
Poor tissue quality
ACL deficiency

37. Open Repair
Rarely used
Numerous studies have proven reduced surgical morbidity with arthroscopic repair
Reserved for peripheral tears in the posterior horn

38. Inside-out Repair
Suture passed on either side of tear with needle cannula
Suture is brought out of capsule
A small skin incision is made
Suture is tied down to capsule
Posterior Horn Repairs

39. Outside-In Repair Sutures passed through the meniscus from the outside
Eliminates need for larger incision
Generally suited for anterior repair
Studies have shown similar results with both techniques

40. All Inside
All-inside repair devices were developed to reduce surgical time, prevent complications resulting from external approaches, and allow access to tears of the posterior horn
Fourth-generation repair devices allow placement of sutures in the meniscus without the aid of an external incision or a suture fixator system

41. All Inside
Self-adjusting, with the anchor located behind the capsule and with a sliding knot that can be tensioned appropriately by the surgeon
Mechanical studies show comparable strength to outside-in sutures

45. Outcomes
Success rates for all techniques reported 70-95%
Second-look scopes show lower success rates of 45-91%
Ligamentous laxity decreases success rate to 30-70%
90% success reported in conjunction with ACL repair

46. Complications Failure to heal Stiffness Articular surface damage
NV structure damage

47. Transplantation Indications: Contraindications:
Recurrent pain after partial or total debridement
symptomatic with ADLs
<50yo
Contraindications:
Malalignment
Laxity
Inflammatory arthritis
Advanced OA

48. Outcomes
Widely varying reports of success (Country differences)
Subjective improvement in tibiofemoral pain
No clear long-term benefit in preventing OA has been established
Grafts seem to do better when placed with a bone block
Preserving some peripheral rim helps to avoid extrusion
Variety of meniscal scaffold options being investigated in animals

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