Marchevsky Meniscal Injury

Meniscal Injury
Meniscal injury is most commonly occurs associated with cranial cruciate ligament disease.
Incidence of meniscal injury a at the time of initial surgery for 1000 cases of cranial cruciate
ligament disease was approximately 33% (1) whilst in a series of 100 cases 59% had medial
meniscal tears. (2)
Meniscal anatomy
The menisci are crescent shaped discs of fibrocartilage. The abaxial border of each meniscus is
thick tapering to a thin axial edge. The distal surface of each meniscus is flat whereas the
proximal surface is convex allowing it to “hug”
the femoral condyles and improve joint
congruity. In the abaxial two thirds of the
menisci, The collagen fibres that make up the
menisci are largely circumferential “tied”
together by radial fibres. Centrally the fibres
are generally radial. Because there are
relatively few radial fibres, tears tend to be
circumferential-­‐ the radial fibres tear and the
circumferential fibres separate abaxially and
more likely to be radial in the thinner central
portions.
Figure 1 From Veterinary Surgery Small Animal
Vol 1 Ed. Tobias and Johnston 2012
The medial meniscus is firmly attached to the
tibia via the caudal and cranial meniscal
ligaments and to the lateral meniscus via the
intermeniscal ligament. The lateral meniscus
is similarly but less firmly attached to the tibia.
In addition the lateral meniscofemoral
ligament firmly attaches it to the
intercondyloid fossa of the femur. It is also
attached to the popliteal tendon. These two
attachments cause it to move with the femoral
condyle. This explains why it is less likely to be
damaged after cranial cruciate ligament
rupture compared with the medial side.
Meniscal function
The concave proximal surfaces of the menisci increase the congruity of the femoral condyles and
the tibial plateau. They contribute in a minor way to joint stability if the cranial cruciate ligament
is intact but if ruptured the menisci adopts a more primary role. The caudal pole acts as a wedge
and stops cranial translation of the meniscus. However this predisposes to meniscal tearing (3)

Procedures that eliminate cranial tibial thrust may not address rotational forces and may explain
why meniscal injury can still occur even after surgery is performed (4)
During weight bearing the contact between the condyles and the menisci increases and they bear
between 40 and 70% of the load. During weight bearing the menisci expand and the
circumferential fibres elongate resulting in hoop stress. This stress is transmitted to the tibia
through the cranial and caudal tibio-­‐meniscal ligaments. Transection of any one of these
ligaments destroys the ability to generate the stress within the meniscus and causes a 140%
increase in peak contact pressure and 50% decrease in contact area on the femoral condyles and
tibial plateau (5).
Meniscal pathology
As noted from the meniscal anatomy, most meniscal tears are circumferential and occur in the
abaxial two thirds of the menisci. The medial meniscus is most affected because it is tightly
connected to the tibia and is wedged between the tibial plateau and the femoral condyles when
the tibia translates cranially leading to tears in the caudal pole. The tears are usually
circumferential vertical tears. They can be incomplete in which case they may not be visible as
the tear son the tibial surfaces. Only careful probing (using a small blunt right angled probe) will
detect this. This may possibly be a cause of meniscal tears that apparently occur soon after
surgery. Vertical tears may be full thickness and in which case will be seen on the femoral
meniscal surfaces and may be non displaced where they appear as a longitudinal tear or
displaced to form the classic bucket handle tears. An extension of the latter is when the torn
meniscal portion tears away at either the cranial or caudal extent. The meniscus can also detach
from the joint capsule (peripheral detachment)
Figure 2 Meniscal tear classification Modified from Thieman et al (6). A, Normal; B,
Non displaced horizontal tear; C, Bucket handle tear; D Flap tear

The lateral meniscal tends to ride with the femoral
condyles and its caudal extent is largely protected.
One arthroscopic study demonstrated meniscal tears
in 77 0f 100 stifles with cranial cruciate ligament
ruptures. These tears were radial, in the cranial pole
and of unknown clinical significance. The actual
mechanism of injury is unknown but was postulated
to occur as a result of the cranial pole of the meniscus
being pinched between the lateral femoral condyle
and the lateral condylar eminence of the tibia.
Figure 3 From Ralphs SC, Whitney WO J Am
Vet Med Assoc 2002 (2) A, Radial lateral
meniscal tear
Meniscal surgery
Approach: The medial meniscus can be accessed from either a lateral or medial
arthrotomy. Laterally it is probably necessary to luxate the patella to get adequate
visualisation of the medial meniscus. Medially a mini arthrotomy can be performed
extending from the mid to distal portion of the patella to the tibial crest. Gelpi retractors
are used to open the joint in a medial to lateral direction. Visualisation is facilitated using
either a Hohmann retractor with the point placed at the back of the tibial plateau and
levered forward using the trochlear as the fulcrum. Alternatively a stifle distractor can be
used and is especially useful for non-­‐assisted arthrotomy.
Detection: A small blunt right-­‐angled probe is invaluable tool for detecting meniscal tears.
It is used to probe the tibial surface of the meniscus. This should be smooth. If the probe
catches then this is likely to be an incomplete longitudinal tear. Additionally non-­displaced
full thickness vertical tears can also be difficult to see and can be retracted
cranially. Subluxating the tibia cranial will also help detect non-­‐displaced caudal pole
tears and peripheral detachments.
Resection: The torn portion should be grasped with hemostats (toothed or otherwise)
and retracted. The attachments should be sharply transected with a number 11 blade
(partial meniscectomy). It is important to examine the remaining meniscus once the
resection has been performed to ensure that another tear is not present. If this is present
or if there is caudal detachment of the remaining portion, then a caudal pole
meniscectomy is performed. I have found very few indications for complete

meniscectomy as the cranial pole is rarely affected and there is a strong attachment to the
medial collateral ligament.
Prevention: Meniscal release has been shown to reduce the incidence of late meniscal
tears to between 1 and 3.7% (6,7,8) However it is not a benign procedure as it alters the
pressure distributions on the medial plateau, decreases the contact area and increases
peak contact pressure. (3,11) Additionally dogs that have undergone extracapsular
stabilisation and meniscectomy developed more arthritis long term than dogs in which
the meniscal remained intact. (10) Therefore there needs to be some rationale behind
performing a meniscal release. The true incidence (using only those cases that had no
meniscal pathology or resection/release at the first surgery) of post-­‐operative meniscal
tears in cases treated with TTA has been variously reported as 10% (12,13), 16% (14),
22% (13), 27% (15) and most recently a staggering 56% (16). (Interestingly this latter
paper also demonstrated a 31% incidence of post-­‐operative tears in dogs treated with
TPLO and Tightrope extracapsular stabilisation (16)) The true incidence of late meniscal
tears in dogs that have had a TPLO performed is reported at 3.7% (17), 3.8% (18), 8.2
(19) and 31% (15). In studies of dogs where extracapsular repair was performed the
incidence of late meniscal tears was 6.1% (20) 31% (15) This may suggest that a medial
meniscal release is warranted when a TTA is performed but is less indicated in cases
treated with TPLO
Meniscal tears area common problem associated with cranial cruciate ligament disease.
There is a high incidence of concurrent meniscal injury at the time of first surgery and a
significant incidence post operatively as well. Examination and careful inspection (visual
and probe) to ensure meniscal injuries are correctly diagnosed and treated. Medial
meniscal release at the time of surgery does reduce the incidence of post operative late
meniscal injury but may not be necessary in cases that have been treated with a TPLO.

1) Fitzpatrick N, Solano M: Predictive variables for complications after tibial plateau
leveling osteotomy with stifle inspection by arthrotomy in 1000 consecutive dogs. Vet
Surg 39:460, 2010
2) Ralphs SC, Whitney WO: Arthroscopic evaluation of menisci in dogs with cranial
cruciate ligament injuries: 100 cases (1999–2000). J Am Vet Med Assoc 221:1601, 2002.
3) Pozzi A, Kowaleski MP, Apelt D, et al: Effect of medial meniscal release on tibial translation
after tibial plateau leveling osteotomy. Vet Surg 35:486, 2006
4) Pacchiana PD, Morris E, Gillings SL, et al: Surgical and postoperative complications associated
with tibial plateau leveling osteotomy in dogs with cranial cruciate ligament rupture: 397 cases
(1998–2001). J Am Vet Med Assoc 222:184, 2003.
5) Pozzi A, Kim S, Lewis D: Effect of transection of the caudal menisco-­‐tibial ligament on
femorotibial contact mechanics. Vet Surg 39:489, 2010
6) Wolf RE, Scavelli TD, Hoelzler MG et al: Surgical and postoperative complications associated
with tibial tuberosity advancement for cranial cruciate ligament rupture in dogs: 458 cases
(2007–2009) J Am Vet Med Assoc 240:1481 2012
7) Fitzpatrick N, Solano M: Predictive variables for complications after tibial plateau
leveling osteotomy with stifle inspection by arthrotomy in 1000 consecutive dogs. Vet
Surg 39:460, 2010
8) Gatineau M, Dupuis J, Planté J; Moreau M: Retrospective study of 476 tibial plateau
levelling osteotomy procedures: Rate of subsequent ‘pivot shift’, meniscal tear and other
complications VCOT 24: 333 2011
9) Thieman K, Pozzi A, Ling C, et al: The contact mechanics of simulated meniscal tears in
cadaveric dog stifles. Vet Surg 38:803, 2009.
10) Innes JF, Bacon D, Lynch C, et al: Long-­‐term outcome of surgery for dogs with cranial
cruciate ligament deficiency. Vet Rec 147:325, 2000.
11) Pozzi A, Litsky AS, Field J, et al: Pressure distributions on the medial tibial plateau
after medial meniscal surgery and tibial plateau levelling osteotomy in dogs. Vet Comp
Orthop Traumatol 21:1, 2008.
12) Hoffmann DE, Miller JM, Ober CP, et al Tibial tuberosity advancement in 65 canine
stifles VCOT 19 219 2006

13)Dymond NL Goldsmid SE Simpson DJ: Tibial tuberosity advancement in 92 canine
stifles: initial results, clinical outcome and owner evaluation. Aust Vet J 88, 281 2010
14) Stein S, Schmoekel H: Short-­‐term and eight to 12 months results of a tibial tuberosity
advancement as treatment of canine cranial cruciate ligament damage. J Small Anim Pract
49:398, 2008
15) Lafaver S, Miller NA, Stubbs WP, et al: Tibial tuberosity advancement for stabilization of the
canine cranial cruciate ligament-­‐deficient stifle joint: surgical technique, early results, and
complications in 101 dogs. Vet Surg 36:573, 2007.
16) Christopher SA Beetem J, Cook JL: Comparison of Long‐Term Outcomes Associated
With Three Surgical Techniques for Treatment of Cranial Cruciate Ligament Disease in
Dogs Vet Surg 432 329 2013
16) Priddy NH, Tomlinson JL, Dodam JR. Complications with and owner assess-­‐ ment of
the outcome of tibial plateau leveling osteotomy for treatment of cranial cruciate ligament
rupture in dogs: 193 cases (1997–2001). J Am Vet Med Assoc 222:1726 2003
19) Kalff S, Meachem S, Preston C, Vet Surg 40 952 2011 Incidence of medial meniscal
tears after arthroscopic assisted tibial plateau leveling osteotomy.
20 Casale SA, McCarthy RJ: Complications associated with lateral fabellotibial suture
surgery for cranial cruciate ligament injury in dogs: 363 cases (1997–2005). J Am Vet Med
Assoc 234:229, 2009.
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