To provide the theoretic basis for treatment and to increase the understanding of the tear patterns of the discoid meniscus, we observed the collagen orientation of the discoid meniscus.
Ten meniscus specimens were used to observe the collagen fibril orientation of the complete type of the discoid lateral menisci. The samples were observed layer by layer under a polarizing filter microscope by using Sirius red staining, and they were also observed under a scanning electron microscope.
The lateral discoid meniscus is classified into 7 layers based on collagen fibril orientation. The femoral surface of the discoid meniscus is covered by dense and well-arranged thick fibrils, which very much resembles a bunched streak. The fibrils show a sagittal isotropic-arranged orientation. However, the tibial surface shows an irregular and anisotropically arranged orientation. In the outer layer, a meshwork of thin fibrils has been observed. The collagen fibrils in the inner layer are radially orientated from the lateral side to the medial side. In the central layer, the peripheral collagen fibrils are displayed as dense bundles running in a circumferential pattern, whereas its medial zone shows as thin, loosely, and irregularly arranged fibrils without a bundle formation. The anterior and posterior zones of the central layer show the collagen fibrils with a straight arrangement in the radial direction.
In the lateral middle zone of discoid meniscus, the collagen fibrils run parallel to the periphery of the meniscus. Therefore, it would be ideally suited for resisting hoop stresses. From this anatomic study, it is apparent that the peripheral portion of the meniscus is constructed to bear a load.
It is strongly recommended that the peripheral portion of the discoid meniscus should be preserved when a resection of the meniscus is mandatory.
[Show abstract][Hide abstract] ABSTRACT: In previous studies, 5% to 20% of patients with a discoid lateral meniscus eventually require surgery bilaterally for symptomatic discoid menisci. However, there are little published data specifically on children who require treatment for discoid menisci in both knees. The purpose of this study is to identify differences in clinical and arthroscopic findings between children who require bilateral versus unilateral treatment for symptomatic discoid lateral menisci.
We retrospectively reviewed the records of all patients aged 18 years or younger requiring treatment of discoid lateral meniscus between 1998 and 2007. Data were collected on 16 patients (32 knees) with symptomatic bilateral discoid menisci and 60 patients treated unilaterally with an asymptomatic contralateral knee.
At initial presentation, children who were treated bilaterally for discoid menisci were younger than those treated unilaterally (10.4 vs. 12.5 y; P=0.021). Patients under 12 years of age were 4.6 times more likely to eventually require surgery on both knees (P=0.015). Watanabe classification was as follows: complete, 65% bilateral versus 30% unilateral; incomplete, 22% bilateral versus 68% unilateral; and Wrisberg, 13% bilateral versus 2% unilateral (P<0.001). The odds of current or future bilateral symptoms requiring treatment were 4.5 times higher in patients with a complete discoid meniscus (P=0.0017) and 8.4 times higher in those with a Wrisberg type (P=0.048). A tear of the lateral meniscus was more likely to be found intraoperatively in unilateral knees than bilateral (90% vs. 72%; P=0.037).
Patient education and long-term follow-up are important for children who present with a discoid meniscus at a young age or with a complete or Wrisberg type, as these patients may be at increased odds of symptomatic discoid meniscus in the contralateral knee, even several years later. Furthermore, evaluation and treatment of discoid lateral meniscus requires vigilance for meniscal tears.
Prognostic study, level III.
[Show abstract][Hide abstract] ABSTRACT: Background: Presently, the treatment options available for patients with horizontal degenerative cleavage tears of the meniscus are limited. These tears are considered an indication for partial or subtotal meniscectomy because when the tear is located within an avascular area, it is difficult to induce healing. However, meniscectomy is not ideal because it disrupts the normal anatomical structure and function of the meniscus. Purpose: To examine the clinical and arthroscopic outcomes following meniscal repair of degenerative horizontal cleavage tears using fibrin clots. Study Design: Case series; Level of evidence, 4. Methods: Vertical sutures were placed in the meniscal tear, and the cleft was filled with fibrin clots before the sutures were tightened. We repaired 18 menisci in 18 consecutive eligible patients using a previously described technique. Three patients with anterior cruciate ligament (ACL) injury who underwent simultaneous ACL reconstruction and 5 patients who did not undergo follow-up arthroscopy within 12 months were excluded. The remaining 10 menisci in 10 patients were evaluated in this study. The mean age of the patients was 35.8 ± 16.5 years, and the mean postoperative follow-up time was 40.8 ± 5.4 months. Pre-and postoperative Lysholm scores, International Knee Documentation Committee (IKDC) subjective scores, and Tegner activity levels were compared. The arthroscopy findings were evaluated at a mean postoperative time of 6.7 ± 2.9 months. Results: The mean Lysholm score improved significantly from 69.3 ± 16.3 points preoperatively to 95.4 ± 3.6 points postoperatively (P < .005). The mean IKDC subjective score also improved significantly from 26.5% ± 19.0% preoperatively to 87.8% ± 7.5% postoperatively (P < .001). The Tegner activity level recovered to the preinjury level in 6 patients and to 1 level below the preinjury level in 4 patients. The follow-up arthroscopies showed complete healing in 7 patients (70%) and incomplete healing in 3 patients (30%).
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