Gert Kristensen, M.D. Aalborg, Denmark. Norway 2007

Transcription

1 Gert Kristensen, M.D. Aalborg, Denmark

2 ????? Treatment???????? How do we treat meniscus lesions in year 2007?

3 Role of the menisci?! Load distribution! Shock-absorbtion! Mechanic stabilization! Lubrication! Proprioception

4 Role of menisci in load distribution on the cartilage Contact area Load 5 Intact knee meniscectomy

5 Menisci fills the empty space between the femoral and tibial condyle in the knee Medial condyle Lateral condyle

6 Menisci fills the empty space between the femoral and tibial condyle in the knee Medial condyle Lateral condyle

7 3D-reconstruction from MR-microscopy! Lat. Fem.! Meniscus! Lat. tibia Setton et al. 1999

8 Tibio-femoral contact pressure maps in vitro A AMIS ET AL

9 Consequence of meniscectomy: 8Grade of cartilage lesion dependent on size of meniscal resection 8Meniscus healing dependent on communication with vascular area

10 Consequence of meniscectomy: Radiological changes after meniscectomy (107 knees,, 5 mth - 14 years)

11 Consequence of meniscectomy: Newer literature confirms a higher incidence of Fairbanks changes even after arthroscopic resection, latest F. Chatain with 22.3% increase in joint space narrowing

12 Meniscus anatomy Ultrastructure of the meniscus Semi-circular fibres are basis for the hoop-forces

13 Menisci transforms axial load to tensile load, the so called hoop-forces + load - load

14 Meniscus load transmission! 50% in straight knee! 85% in 90 0 flexed knee! This is due to a decrease in condyle radius during flexion

15 Consequence of meniscectomy: If normal load is concentrated on a smaller area the load in this area becomes abnormal Leads to osteoarthritis

16 The role of the meniscus as stabilizor 20 Anterior displacement in mm: Normal knee ACL cut Flexion (degree) Med. Meniscus cut ACL AND Meniscus cut

17 That s s why the anterior drawer test doesn t t function if medial meniscus is intact

18 Thus an intact meniscus is of great importance for the normal function of the knee

19 Menisci are mobile structures!

20 Menisci are mobile structures!

21 Posterior excursion of menisci during flexion: Medial meniscus: 5.1 mm Lateral meniscus: 11.2 mm (Thompson, Fu 1991)

22 Lubrication! 74% weight is water! Compression squeezes out water into joint space! Allow smoother gliding of surfaces! Also increases contact area

23 Blood supply to the medial meniscus

24 Blood supply to the lateral meniscus

25 RED/ RED RED/ WHITE WHITE/WHITE

26 ! Vascular supply to the menisci originates from medial and lateral genicular arteries

27 Vertical Sutures?

28 Vascular supply to the meniscus is affected by vertical sutures (Albrecht-Olsen a study in pigs personal communication) Suture

29 Meniscus structure Central 2/3 radial and circumferential Peripheral 1/3 circumferential fibers

30 Meniscus structure!femoral lamina!tibial lamina

31 NERVE INNERVATION! Nociceptors! Mechanoreceptors! The menisci are a source of proprioceptive information regarding position, direction, velocity,, acceleration and deceleration of the knee

32 Meniscus nerve supply

33 Meniscus nerve supply! Free nerve endings have been localized in the meniscus! At least 3 different mechanoreceptors have been identified so far! The anterior and posterior horns have the richest nerve supply! Menisci no doubt play a role in proprioception

34 Meniscus nerve supply! Free nerve endings have been localized in the meniscus! At least 3 different mechanoreceptors have been identified so far! The anterior and posterior horns have the richest nerve supply! Menisci no doubt play a role in proprioception

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