Introduction and Instrumentation


1
Introduction and Instrumentation


1.1 Introduction


Arthroscopy is the most significant advance in small animal orthopedics that has occurred during my 50 years of professional lifetime.


image Arthroscopy provides more information about intra‐articular pathology than any other diagnostic technique. The most important advantages of arthroscopy are visual access to more joint area, magnification produced by the telescopes and video systems, excellent illumination, and a clear visual field when continuous irrigation is employed. Arthroscopy is also minimally invasive, reduces trauma, shortens operative times, and decreases recovery times. The small sizes of telescopes available today allow placement into the deepest parts of joints and combined with angulation of the field of view, 30° for most arthroscopes, provide visual access to more area of joints than can be achieved with open surgery. Arthroscopes magnify intra‐articular structures allowing visualization of anatomical details and pathologic changes that are beyond the resolution of radiographs, CT, MRI, or what can be seen with open surgery (Video 1.1). Submacroscopic lesions that elude us with open surgical exploration can be easily seen with arthroscopy. High‐intensity lighting is passed directly through the arthroscope providing perfect illumination of everything in the field of view of the telescope. Irrigation employed with arthroscopy maintains a clear field of view by continuously flushing blood and debris away from the end of the telescope. This is all done with minimally invasive technique and far less tissue trauma than with an arthrotomy. Speed is not the most important criteria or the most important advantage of arthroscopy over open arthrotomy, but for the experienced arthroscopic surgeon, anesthesia and procedure times are significantly shorter than with conventional open surgery. Postoperative recovery after arthroscopy is also much faster than following an open arthrotomy. This time comparison is an important advantage of arthroscopy. Most dogs recover to their preoperative status of lameness and pain within a few hours after arthroscopy. Many dogs are better than their preoperative level of function by the time they are released from the hospital on the day after arthroscopy. Arthroscopy is commonly performed as an outpatient procedure with a release on the same day as surgery. Activity restriction is not needed for portal site healing. The time required for healing of intra‐articular structures after arthroscopy for conditions such as OCD and medial coronoid process disease (MCPD) has not been studied or effectively compared with healing after open surgery.


There are few disadvantages of arthroscopy. The most significant disadvantage is that arthroscopy is the most difficult of all endoscopies to learn. Arthroscopy’s technical difficulty with its long slow learning process for both diagnostic applications and for performing corrective surgical procedures makes it a challenge to gain proficiency. Arthroscopy requires considerable practice, patience, and persistence to master. Reasons for arthroscopy’s difficulty are related to the small space involved, confinement by rigid bony structures, and the anatomic complexity of some joints such as the stifle. Even with its difficulties, developing proficiency with arthroscopy is within the grasp of most who are willing to make the effort and put in the time to learn. Expense of instrumentation is a relative disadvantage as the cost of the equipment and instrumentation for arthroscopy is significant but is no more than other sophisticated instrumentation used in small animal practice today. The limitation of small patient size is shrinking as instrument size decreases and as our skill level and experience increase.


Arthroscopy is indicated whenever there is a history, physical findings, imaging changes, or laboratory result suggestive of joint disease. A history of lameness, stiffness, difficulty or reluctance to get up, reluctance to go up or downstairs, reluctance to get up and down off the couch or the favorite chair, and inability to get in and out of the car or truck; combined with joint pain, swelling or thickening, crepitus, reduced range of joint motion, or joint instability on physical examination are definite reasons to perform arthroscopy. Radiographic, CT, MRI, or ultrasound abnormalities of increased joint fluid or joint capsule thickening, periarticular osteophytes, periarticular sclerosis, OCD lesions, ununited anconeal processes, ununited caudal glenoid ossification center, intra‐articular fractures or chips, periarticular bone lysis, tendon and ligament abnormalities, or any other changes involving a joint are also indications for arthroscopy. Normal radiographic, CT, MRI, or ultrasound findings do not preclude arthroscopy as a diagnostic technique if history and physical findings point to joint involvement. Arthroscopy is indicated whenever we need more information about a joint than can be obtained with any less invasive technique.


Arthroscopy is most commonly performed in the shoulder, elbow, and stifle in dogs. Arthroscopy is less commonly performed on the radiocarpal, hip, and tibiotarsal joints. Arthroscopy is easier to perform in large dogs but has been done effectively in dogs as small as seven pounds. Arthroscopy has also been performed in the shoulder, elbow, and stifle of cats but its use is largely unexplored in this species. The same positioning, procedures, techniques, and portals that are used in dogs are used for cats.


Conditions that have been diagnosed with arthroscopy (Table 1.1) include osteochondritis dissecans (OCD) of the shoulder, stifle, elbow, and tibiotarsal joints (Van Bree and Van Ryssen 1998); partial and complete cranial and caudal cruciate ligament ruptures; meniscal injuries; medial coronoid processes disease (MCPD); ununited caudal glenoid ossification center (UCGOC), ununited anconeal process (UAP), ununited supraglenoid tubercle, degenerative joint disease (DJD); intra‐articular fractures; immune‐mediated arthritis; synovitis; partial or complete bicipital tendon rupture; injury to other intra‐articular soft tissues of the shoulder, soft tissue injury of intra‐articular structures of the elbow, radiocarpal, stifle, and hip joints; septic arthritis; and neoplasia. Arthroscopic assessment of femoral head and acetabular articular cartilage condition in young dysplastic dogs have been used for case selection and to predict results with pelvic osteotomy surgery. Cartilage injury or chondromalacia secondary to instability, deformity, or inflammatory processes is more easily identified and the extent of damage scored more accurately than with open surgery.


Table 1.1 Diagnoses with arthroscopy.
























All joints Degenerative joint disease
Chondromalacia
Neoplasia
Synovitis/villus synovial proliferation
Intra‐articular Fractures
Immune‐mediated polyarthropathies
Septic arthritis
Shoulder joint OCD of the humeral head
Bicipital tendon ruptures – partial and complete
Medial glenohumeral ligament and subscapularis tendon injuries
Lateral glenoid labrum separations
Ununited caudal glenoid ossification center
Ununited supraglenoid tubercle
Supraspinatus tendon injuries
Glenoid cartilage defects
Elbow joint Medial coronoid process pathology/fragmentation
Lateral coronoid process pathology/fragmentation
OCD of the humeral condyle
Ununited anconeal process
Joint incongruity/growth deformity
Incomplete humeral condyle ossification
Radiocarpal joint Radial carpal bone fractures
Chip fractures of the dorsal margin of the distal radius
Ligament and joint capsule tears
Hip joint Hip dysplasia
Dorsal joint capsule tears
Aseptic necrosis of the femoral head
Stifle joint Cranial cruciate ligament ruptures – partial and complete
Caudal cruciate ligament ruptures – partial and complete
Meniscal injuries
OCD of the femoral condyle
Medial patellar luxation/lateral patellar ligament rupture
Long digital extensor tendon injuries
Popliteal tendon avulsion
Cruciate stabilization failure
Hock joint OCD of the talus

Operative procedures currently being performed with arthroscopy (Table 1.2) include removal of OCD cartilage flaps and debridement of the cartilage defects in the shoulder, elbow, stifle, and tibiotarsal joints (Bertrand et al. 1997; Bilmont et al. 2018; Cook et al. 2001; Gielen et al. 2002; McCarthy 1999; Miller and Beale 2008; Olivieri et al. 2007; Person 1989; Rochat 2001; Van Bree and Van Ryssen 1998); coronoid process fragment removal (McCarthy 1999; Rochat 2001) and coronoid process revision or subtotal coronoidectomy (McCarthy 1999), free joint body (arthrolith) removal (Smith et al. 2012), bicipital tendon transection (Bergenhuyzen et al. 2010; Cook et al. 2005; Rochat 2001), carpal chip removal (McCarthy 2005), partial and total meniscectomy (Ertelt and Fehr 2009; Ridge 2006; Ritzo et al. 2014; Rochat 2001), cruciate ligament debridement (Rochat 2001), meniscal release (Austin et al. 2007; Kim et al. 2016; McCarthy 1999), ununited caudal glenoid ossification center removal (McCarthy 2005), ununited supraglenoid tubercle removal (McCarthy 2005; Serck and Wouters 2019), ununited anconeal process removal (McCarthy 2005), screw fixation of ununited anconeal process fragments, osteophyte removal in chronic degenerative joint disease of the elbow and tarsus (McCarthy 2005), intra‐articular repair of ruptured cranial cruciate ligaments (Bolia and Böttcher 2015; Person 1987; Winkels et al. 2010), fixation of avulsed ligament attachments, medial patellar luxation management (Bevan and Taylor 2004), assisted repair of intraarticular fractures (Beale and Cole 2012; Bright and May 2011; Cole and Beale 2020; Cusack and Johnson 2013; Deneuche and Viguier 2002; Perry et al. 2010), intra‐articular management of shoulder instability (Franklin et al. 2013; Mitchell and Innes 2000; Ridge et al. 2014), neoplasia management (Arias et al. 2009; Scherrer et al. 2005), septic arthritis management (Fearnside and Preston 2002; Luther et al. 2005), and more. The majority of procedures and publications relate to application of arthroscopy in dogs, but this technique has also been performed in cats (Bardet 1998; Beale and Cole 2012; Bright 2010; Cole and Beale 2020; Cusack and Johnson 2013; Mindner et al. 2016; Ridge 2009; Serck and Wouters 2019; Staiger and Beale 2005).


Table 1.2 Operative procedures performed with arthroscopy.


















Shoulder joint OCD cartilage flap removal and lesion debridement
Bicipital tendon transection
Ununited caudal glenoid ossification center fragment removal
Ununited supraglenoid tubercle fragment removal
Intra‐articular soft tissue injury stabilization
Intra‐articular or assisted fracture repair
Elbow joint Medial coronoid process fragmentremoval/process revision
OCD cartilage flap removal and lesion debridement
Anconeal process removal
Osteophyte resection
Intra‐articular or assisted fracture repair
Radiocarpal joint Carpal chip removal
Intra‐articular or assisted fracture repair
Stifle joint Cruciate ligament debridement/removal
Meniscectomy – partial/total
OCD cartilage flap removal and lesion debridement
Meniscal release
Intra‐articular or assisted fracture repair
Hock joint OCD cartilage flap removal and lesion debridement
Free joint body and tarsal chip fracture fragment removal
Intra‐articular or assisted fracture repair

1.2 Instrumentation and Equipment


1.2.1 Arthroscopes


Rigid telescopes used for arthroscopy range in size from 1.9 to 5.0 mm diameter. Telescopes in use today are designed using what is termed a Hopkins rod lens system (Figure 1.1) for image transmission that has dramatically improved image quality over previous lens systems. Telescopes commonly used for small animal arthroscopy (Table 1.3) include a long 2.7 mm arthroscope also called the 2.7 mm multipurpose rigid telescope (MPRT), a 4.0 mm arthroscope, a short 2.7 mm arthroscope, a 2.4 mm arthroscope, and a 1.9 mm arthroscope (Figure 1.2). These telescopes all have a 30° visual angle, but other angles are available (Figure 1.3). Each has advantages, disadvantages, and specific best applications.


The 2.7 mm MPRT was for years promoted as the telescope of choice for arthroscopy in small animals because it had the best optics of all the small telescopes and its length allows it to be used for multiple endoscopic techniques. This recommendation has changed with improvement of the optics of the 2.4 mm arthroscope, which now equals or exceeds those of the 2.7 mm MPRT. The 2.4 scope is shorter, 11 cm vs 18 cm, smaller, with a better blunt obturator design making it much easier to insert and use in the small joints of our patients. This size and design allow procedures to be performed with less joint damage.


One of the previous arguments for recommendation of the 2.7 mm MPRT was that it can be used for many endoscopic techniques commonly performed in small animal practice and is why this endoscope is termed the MPRT. The larger size of this telescope and the design of the blunt obturator increase the difficulty of establishing a telescope portal for arthroscopy. The other major disadvantage of this telescope is its length, which makes manipulations more difficult for arthroscopy with the finite movements needed for maneuvering the visual field within small joints combined with the long fulcrum produced by a video camera on the end of the telescope. The demands of arthroscopy for effective application in small animals today combined with the need for continued improvement in technique and results no longer allow us to substitute a multipurpose telescope, when a better single application instrument is available. The 2.4 mm arthroscope is currently the telescope of choice for small animal practice.

Photo depicts a diagram of the Hopkins rod lens system shown in the telescope at the bottom and a conventional lens system in the telescope at the top. Hopkins rod lenses are the standard design for arthroscopes in current use today.

Figure 1.1 A diagram of the Hopkins rod lens system shown in the telescope at the bottom and a conventional lens system in the telescope at the top. Hopkins rod lenses are the standard design for arthroscopes in current use today.


Source: Photo courtesy of KARL STORZ: © KARL STORZ SE & Co KG, Germany.


Table 1.3 Telescopes used for small animal arthroscopy.















































Arthroscope diameter Telescope length (cm) Telescope angle (°) Telescope part number (Karl Storz)
4.0 mm 18 30 64230 BWA
12 30 a67728 BWA
Endocameleon 8 15 T0 90 (Variable) 28731 AE
2.7 x Long (MPRT) 18 30 a 64029 BA
2.7 mm Short 11 30 a 67208 BA
2.4 mm 11 30 a 64300 BA
1.9 mm 10 30 a 64301 BA
6.5 30 28305 BA

a Shown in Figure A I 2.

Photo depicts arthroscopes commonly used in small animal practice from bottom to top: the long 2.7 mm multipurpose rigid telescope (MPRT), 4.0 mm arthroscope, short 2.7 mm arthroscope, 2.4 mm arthroscope, and 1.9 mm arthroscope. These telescopes all have a viewing angle of 30 degrees. The 2.7 mm multipurpose telescope has a working length of 18 cm; the 4.0 mm, short 2.7 mm, and 2.4 mm arthroscopes have a working length of 11 cm; and the 1.9 mm arthroscope with 6.5 cm working length. These telescopes are all autoclavable.

Figure 1.2 Arthroscopes commonly used in small animal practice from bottom to top: the long 2.7 mm multipurpose rigid telescope (MPRT), 4.0 mm arthroscope, short 2.7 mm arthroscope, 2.4 mm arthroscope, and 1.9 mm arthroscope. These telescopes all have a viewing angle of 30°. The 2.7 mm multipurpose telescope has a working length of 18 cm; the 4.0 mm, short 2.7 mm, and 2.4 mm arthroscopes have a working length of 11 cm; and the 1.9 mm arthroscope with 6.5 cm working length. These telescopes are all autoclavable.


Source: Photo courtesy of KARL STORZ: © KARL STORZ SE & Co KG, Germany.

Schematic illustration of a diagram showing the angle of view of telescopes used for arthroscopy. Thirty degrees is the angle of view of all commonly used telescopes for arthroscopy. Zero degree and seventy degrees arthroscopes are available but are rarely used.

Figure 1.3 A diagram showing the angle of view of telescopes used for arthroscopy. Thirty degrees is the angle of view of all commonly used telescopes for arthroscopy. Zero degree and seventy degrees arthroscopes are available but are rarely used.


Source: Photo courtesy of KARL STORZ: © KARL STORZ SE & Co KG, Germany.


A 2.7 mm arthroscope is available with a working length of 11 cm. Its shorter length is an advantage over the 2.7 mm MPRT for arthroscopy making handling the telescope in small joints much easier. The only other advantage of this telescope over the 2.4 mm arthroscope is that it is more robust with less chance of breakage, especially when used by a beginner. Disadvantages are that the optics are not as good as either the 2.4 mm arthroscope or the 2.7 mm MPRT and the blunt obturator design makes portal placement more difficult.


The 1.9 mm arthroscopes are available in 10 mm and 6.5 mm lengths. The smaller size of these telescopes is an advantage for use in smaller joints such as the radiocarpal joint, tibiotarsal joint, and for use in small dogs or cats. Their disadvantages are that they are fragile breaking more easily, the field of view is significantly smaller increasing the difficulty of joint visualization, and the optics are not as good making them less effective for documentation purposes.


Four‐millimeter diameter telescopes are also available for use in small animals but are too large for most joints in most patients. A 4 mm arthroscope has been used in the stifle joint of larger dogs and in the shoulder joint in giant breeds. Four‐millimeter telescopes are available in lengths of 18 cm and a shorter 12 mm version. A 4.0 Endocameleon arthroscope is a new addition to the armamentarium for large joint arthroscopy with a variable direction of view from 15° to 90°.


The shorter length arthroscopes have another advantage in that they can be held in a pistol grip fashion with the surgeon’s index finger on the skin at the portal site to accurately and easily maintain a constant depth of telescope insertion. This greatly reduces the number of times the field of view is lost because the telescope is inserted too deep or the telescope is inadvertently pulled out of the joint. This is particularly important for beginners.


A significant advance in telescope technology is that most telescopes are now autoclavable. The autoclavable telescopes are labeled as autoclavable. This greatly facilitates instrument turnaround and practice efficiency.


1.2.2 Sheaths and Cannulas


1.2.2.1 Telescope Sheaths


Arthroscopes are used with a cannula or sheath to protect the telescope and provide a channel for fluid inflow (Figure 1.4 and Table 1.4). A specifically matched sheath is required for each specific telescope size. Telescope sheaths come with a sharp trocar and a blunt obturator. The blunt obturator is preferred because it causes less damage to joint cartilage when establishing the telescope portal. Sheaths for the smaller telescopes used in small animal practice typically have a single fixed stopcock with a Luer lock connector used for fluid inflow. Cannulas are also available with two stopcocks and stopcocks that rotate on the cannula. All sheaths have a locking mechanism that fixes the cannula to the telescope. This locking mechanism is very important as it protects the telescope from being damaged. When locked in place, the distal tip of the telescope is aligned with the distal tip of the sheath and this protects the distal lens of the telescope. More importantly, when the telescope is locked in place, the sheath protects against excessive bending stresses along the telescope shaft. This locking mechanism also creates a watertight seal at the proximal end of the sheath so that irrigating fluid flows into the joint. It is very important that the telescope is properly locked in place for fluid flow, to prevent interference of the tip of the cannula with the visual field, and most importantly, to prevent telescope damage.


The locking mechanism of telescope cannulas has evolved over time from a rotating ring to a sliding box and, more recently, to a snap‐in design with spring‐loaded locks (Figure 1.5). The rotating ring is the traditional coupling mechanism being the oldest and simplest configuration for locking the telescope to the cannula. This design works well, has withstood the test of time for dependability, and is easy to use. The sliding box or automatic lock design is slightly easier to use, is more secure than the traditional coupling mechanism, but can become hard to slide over time eventually sticking and becoming inoperable. The snap‐in coupling is the most recent locking mechanism, is the easiest to use, and provides secure attachment of the telescope to the cannula.

Photo depicts arthroscope sheaths with blunt obturators from left to right: blunt obturator for the 2.7 mm long arthroscope or MPRT, sheath for the 2.7 mm long arthroscope or MPRT telescope with a single rotatable stopcock and with a blunt obturator inserted, blunt obturator for the 2.4 mm telescope, sheath for the 2.4 mm arthroscope with a single fixed stopcock, blunt obturator for the short 2.7 mm arthroscope, sheath for the short 2.7 mm arthroscope with a single rotatable stopcock, an operating cannula with a blunt obturator in place, sheath for the1.9 mm arthroscope with a single fixed stopcock and with a blunt obturator inserted, and an egress cannula with a blunt obturator in place.

Figure 1.4 Arthroscope sheaths with blunt obturators from left to right: blunt obturator for the 2.7 mm long arthroscope or MPRT, sheath for the 2.7 mm long arthroscope or MPRT telescope with a single rotatable stopcock and with a blunt obturator inserted, blunt obturator for the 2.4 mm telescope, sheath for the 2.4 mm arthroscope with a single fixed stopcock, blunt obturator for the short 2.7 mm arthroscope, sheath for the short 2.7 mm arthroscope with a single rotatable stopcock, an operating cannula with a blunt obturator in place, sheath for the1.9 mm arthroscope with a single fixed stopcock and with a blunt obturator inserted, and an egress cannula with a blunt obturator in place. The telescope cannulas in this image all have the snap‐in coupling design.


Source: Photo courtesy of KARL STORZ: © KARL STORZ SE & Co KG, Germany.


Table 1.4 Telescope sheaths used for small animal arthroscopy.
























































Arthroscope Sheaths part number (Karl Storz) Obturators part number (Karl Storz)
4.0 mm/18 cm/30° (64 230 BWA) 64124AR 65127BS/BT
4.0 mm/12 cm/30° (64 728 BWA) 64126KR 64129BT
4.0 mm Endocameleon/18 cm (28 731 AE) 28 136 EC 28126 BC/BT
2.7 mm/18 cm/30° (64 029 BA) a64128 AR 63122 AS/AB
Snap in 28132S 28132BC/BT
2.7 mm/11 cm/30° (67 208 BA) a64147 BN 64147 BS/BT
Snap in 26133DS 28133BC
2.4 mm 10 cm/30° (64 300 BA) a64303 BN 64303 BU/BV
Snap in 28303BN 28302BU/BV
1.9 mm/11 cm/30° (64 301 BA) 64 302 BN 64302 BS/BT
1.9 mm/6.5 cm/30° (28 305 BA) a28306 BN 64306 BS/BT
Snap in 64306BN 64306BS/BT

a Shown in Figure A I 4.


1.2.2.2 Operative Cannulas


Operative portals are established with a cannula (Figure 1.6 and Table 1.5) or using a free passage technique where instruments are placed through the soft tissues overlying the joint without using a cannula. Conflicting opinions exist about which technique is best, but both are effective with each having its indications, advantages, and disadvantages. When a cannula is used, access for instrumentation is established and maintained by placing the cannula into the joint at the operative portal site. This technique has the advantage of facilitating reinsertion of instruments. The disadvantages of operative cannulas are that they limit the size of instruments that can be placed into the joint and the size of tissue fragments that can be removed. Operative cannulas can interfere with instrument manipulation because of small joint size with very short distances between the joint capsule and operative sites. Operative cannulas are also difficult to keep in place tending to come out with instrument and tissue removal.

Photo depicts locking mechanism designs for attaching sheaths to telescopes. From left to right: A snap-in coupling mechanism with spring-loaded locks, a traditional rotating ring locking mechanism, and an automatic lock.

Figure 1.5 Locking mechanism designs for attaching sheaths to telescopes. From left to right: A snap‐in coupling mechanism with spring‐loaded locks, a traditional rotating ring locking mechanism, and an automatic lock.


Source: Photo courtesy of KARL STORZ: © KARL STORZ SE & Co KG, Germany.

Photo depicts operating cannulas for arthroscopy from left to right: a 5.5 mm operating cannula with its blunt obturator in place, a 4.5 mm operating cannula with a blunt obturator, a 2.5 mm operating cannula with a sharp trocar in place, and a 3.5 mm operating cannula with a blunt obturator. Rubber gaskets for these cannulas are used when indicated.

Figure 1.6 Operating cannulas for arthroscopy from left to right: a 5.5 mm operating cannula with its blunt obturator in place, a 4.5 mm operating cannula with a blunt obturator, a 2.5 mm operating cannula with a sharp trocar in place, and a 3.5 mm operating cannula with a blunt obturator. Rubber gaskets for these cannulas are used when indicated.


Source: Photo courtesy of KARL STORZ: © KARL STORZ SE & Co KG, Germany.


For free passage of instruments without a portal cannula, joint access is created with a sharp incision into the joint using a no. 11 blade followed by blunt dissection through tissues overlying the joint using a curved mosquito hemostat. Instruments are passed into the joint directly through the tissues. This technique has the advantages of allowing passage of larger instruments, removal of larger pieces of tissue, eliminating interference of the cannula during operative instrument manipulation, and eliminating the problem of the cannula being displaced by removal of instruments and tissues. The primary disadvantage of this technique is increased difficulty of instrument reinsertion through the operative portal. A combination of the two techniques has been employed using the one that best fits the current procedure or stage of the procedure.


Operative cannulas that have been used for small animal arthroscopy are 2.5 mm diameter for 2.0 mm instruments, 3.5 mm diameter for 2.8 mm instruments, 4.5 mm diameter for 3.5 mm instruments, and 5.5 mm diameter for 4.8 mm instruments. Cannulas come with sharp trocars or blunt obturators for insertion and are supplied with rubber gaskets to prevent fluid leakage when instruments are in place. If increased pressure in the joint is needed for a specific procedure, the gaskets are used. There are no valves or stopcocks in these cannulas, so they do not hold fluid in the joint when an instrument is not in place. Gaskets increase the resistance of instrument insertion or removal and increase the tendency for cannulas to be removed when instruments are withdrawn.


Table 1.5 Operating cannulas used for small animal arthroscopy.





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Nov 28, 2021 | Posted by in SMALL ANIMAL | Comments Off on Introduction and Instrumentation
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Cannula diameter (mm)