Page 227 - WSAVA2018
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In cases where cruciate instability is present 2 methods exist to create and maintain distraction or cranial drawer of the tibia at arthrotomy.
The first method is the use of a self-retaining stifle joint distractor. The proximal tip of the distractor is placed in the proximal part of the intercondylar fossa. The intercondylar fossa is the origin of the caudal cruciate ligament so care should be taken when placing the proximal tip to avoid damage to the ligament.
The distal tip of the distractor is positioned caudal to and under the intermeniscal ligament. The intermeniscal ligament is not able to be visualized because it is covered by the fat pad. Gentle retraction of the Gelpi retractor distally helps retract the fat pad distally and provide better access to place the distal tip of the
stifle distractor immediately caudal to the intermeniscal ligament. Alternatively, the Senn retractor can be used for this purpose.
The intermeniscal ligament lies immediately cranial to the insertion of the cranial cruciate ligament. Even in cases of complete cranial cruciate rupture the insertional end of the cranial cruciate is visible and can be used as a guide to find the intermeniscal ligament.
Once both tips of the distractor are in the correct location the joint is distracted. Provided the distal tip is correctly positioned caudal to and loading the intermeniscal ligament it will not pull out. If the distractor is pulling out distally it is because the tip has been placed into the fat pad instead of caudal to the ligament. Slight extension
of the leg with the distractor in place will partly open the caudal aspect of the femoro-tibial joint and facilitate examination of the caudal horn of the menisci. The caudal horn of the medial meniscus is the area where the vast majority of significant meniscal injuries occur.
Various stifle distractors and sizes are available. A “speedlock” / “spinlock” locking mechanism is preferable to a ratchet locking system.
The stifle joint distractor simplifies exploration of the stifle joint in nearly all cases. Combined with a Gelpi retractor, meniscal probe and good lighting and suction it allows single-handed examination of the stifle joint.
The second method for creating effective distraction
of the stifle joint to examine the menisci involves a combination of a narrow-bladed (12mm or less) Hohmann retractor and a sharp-pointed Senn retractor and necessitates a surgical assistant.
A Gelpi retractor is placed as previously described. The Senn retractor is placed into the infrapatella fat pad and the tibia pulled cranially.
The point of the Hohmann retractor is inserted through the intercondylar space of the femur and carefully hooked over the caudal aspect of the tibial plateau taking care not to damage the caudal cruciate ligament.
The Hohmann retractor is then used to lever the tibia cranially and the femur caudally by pushing the handle of the Hohmann retractor in a caudal direction against the femoral trochlea. Use of a narrow bladed Hohmann is necessary to avoid damaging the articular cartilage of the trochlea ridges.
Single-handed exploration is not possible with this method.
Relevant meniscal anatomy: what do you need to know to diagnose and treat meniscal injury?
The menisci are biconcave, C-shaped fibrocartilaginous discs with their open part directed towards the axis of the bone. The medial and lateral menisci are
remarkably different to each other.
In cross section the menisci are wedge-shaped being thickest on their convex abaxial border and thinnest on the concave axial border. The menisci are held in position by 6 meniscal ligaments. To treat a meniscal tear to the caudal horn of the medial meniscus you will need to cut part or all of the caudal meniscotibial ligament. So..... you need to be very familiar with
the meniscal anatomy if you are going to safely and effectively treat meniscal injuries in cruciate disease cases.
Both menisci are attached to the tibia by a cranial and caudal meniscotibial ligament. Each of these 4 ligaments is a short strong ligament on the axial or central end of each meniscus.
The menisci are attached to each other by an intermeniscal ligament that joins their cranial horns and lies immediately cranial to the tibial insertion of the cranial cruciate ligament.
The caudal horn of the lateral meniscus is also attached to the caudal part of the medial femoral condyle by the meniscofemoral ligament of the lateral meniscus. The medial meniscus lacks any femoral attachment.
The medial meniscus is also firmly secured abaxially
or peripherally to the joint capsule and the medial collateral ligament. Conversely the lateral meniscus has no attachment to the lateral collateral ligament and has limited caudal capsular attachments, especially in the region of the popliteal tendon. It is only the cranial part of the lateral meniscus that has a firm capsular attachment.
It is this difference in attachment of the menisci that renders the medial meniscus less mobile than the lateral meniscus and explains the much higher incidence of damage to the medial meniscus.
Why are significant lateral meniscal injuries rare?
The lateral meniscus, because of its meniscofemoral ligament and minimal capsular attachments, moves with the lateral femoral condyle and is not subject to
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