- See:
-
Discoid Meniscus::
-
Types of Meniscal Tears;
- Discussion:
- in shape
medial meniscus resembles a C, whereas lateral meniscus is
more sharply curved and resembles an O that is unclosed medially;
- lateral meniscus is much more of closed circle in uniform width from anterior to posterior;
- it has more of tibial surface than does
medial meniscus & posteriorly is attached in intercondylar
area to PCL via ligaments of Humphry (the anterior menisco-femoral ligament) &
Wrisberg (
posterior meniscal femoral ligament);
- lateral meniscus is 4-5 mm thick, and has a width of 10-12 mm;
- the lateral meniscus bears upto 70% of medial compartment contact pressures;
- Soft Tissue Attachments:
- unlike medial meniscus there is no attachment to its adjacent collateral ligament (
LCL);
- it is attached to the tibial plateau via the coronary (menisco-femoral) ligament, except
in the region of the popliteal hiatus;
- posteriorly the lateral meniscus is attached to the medial femoral condyle, via
meniscofemoral ligaments;
- Partial Meniscectomy:
- menisci trasmit upto 70% of joint loads;
- partial menisectomy may increase peak loads upto 65% whereas total meniscectomy may
increase peak loads upto 235%;
- the radiographic consequences of total menisectomy have been characterized by Fairbank and include:
joint space narrowing, squaring of the condyle, and ridge formation;
- in the report by C. Hoser et al, the authors studied the outcome of partial lateral meniscectomy of 31
knees in 29 patients whose knees were otherwise normal;
- mean follow-up was 10.3 years;
- according to the Lysholm score, 14 knees were rated as excellent, four as good, five as fair and
eight as poor, with a mean score of 80.5 points;
- radiologically, only one lateral compartment was classified as grade 0, eight as grade 1, nine
as grade 2, 11 as grade 3, and two as grade 4 according to Tapper and Hoover;
- no significant (p < 0.05) correlation was found between the amount of tissue resected and the
subjective, clinical and radiological outcome;
- although early results of lateral meniscectomy may be satisfactory, we have demonstrated that
in the long term there was a high incidence of degenerative changes, a high rate of
reoperation (29%) and a relatively low functional outcome score;
- ref: Long-term results of arthroscopic partial lateral meniscectomy in knees without associated damage
C. Hoser et al. J Bone Joint Surg [Br] 2001;83-B:513-6.
- Lateral Meniscal Repair:
- if tear is w/in 3 mm of the periphery, it is considered vascular;
- area 3-5 mm from periphery is grey zone, & > 5 mm from periphery is considered avascular;
- unstable tears or tears within vascular zone that are > 7 mm are repairable;
- Misc:
-
meniscal cysts:
- associated w/ lateral meniscal tears which extend into the capsule;
- in most cases, the meniscus tear is of horizontal cleavage type;
- pain located to the joint line;
- palpable and visible mass is usually noticed w/ the knee in extension (may diminish w/ flexion);
- mass is most often located at the joint line (anterior to the LCL), but may be located at distal aspect of iliotibial band;
- open excision is usually required;
- references:
- Arthroscopic treatment of cysts of the menisci. A preliminary report.
JS Parisien.
CORR. Vol 257. 1990. p 154-158.
-
Arthroscopic treatment of cysts of the lateral meniscus.
- Arthroscopic treatment of meniscal cyst.
RKN Ryu and AJ Ting.
Arthroscopy Vol 9. 1993. p 591-595.
"Aggressive" nontreatment of lateral meniscal tears seen during anterior cruciate ligament reconstruction.
Isolated lateral meniscectomy: a study of 26 patients with isolated tears.
LA Yocum et al.
JBJS. 61-A. p 338. 1979
The effects of arthroscopic partial lateral meniscectomy in an otherwise normal knee: a retrospective review of functional, clinical, and radiographic results.
Partial lateral meniscectomy in athletes.
The effect of lateral meniscectomy on motion of the knee.
Arthroscopic treatment of cysts of the lateral meniscus.
Lateral meniscal variant with absence of the posterior coronary ligament.
