Chapter 101 - Stifle Flashcards
What is the approximate volume of the medial femorotibial compartment (MFT) in mL?
a) 31.67 mL ± 5.77 mL
b) 41.67 mL ± 5.77 mL
c) 51.67 mL ± 2.89 mL
d) 61.67 mL ± 2.89 mL
Answer: b) 41.67 mL ± 5.77 mL
What percentage of horses show communication between the femoropatellar joint (FP) and the medial femorotibial joint (MFT)?
a) 60% to 65%
b) 70% to 75%
c) 80% to 85%
d) 90% to 95%
Answer: a) 60% to 65%
In which percentage of limbs does mepivacaine diffusion occur from the LFT to the FP?
a) 80%
b) 85%
c) 90%
d) 95%
Answer: c) 90%
The standing femorotibial joint angle is approximately:
a) 140 degrees
b) 150 degrees
c) 160 degrees
d) 170 degrees
Answer: b) 150 degrees
What is the percentage range of horses showing communication between the femoropatellar joint (FP) and the lateral femorotibial joint (LFT)?
a) 1% to 25%
b) 5% to 10%
c) 10% to 25%
d) 25% to 50%
Answer: c) 1% to 25%
At what age is the patella fully ossified in horses?
a) 2 months
b) 4 months
c) 6 months
d) 12 months
Answer: b) 4 months
How many centers of ossification does the stifle of a horse have at birth?
a) 4
b) 5
c) 6
d) 7
Answer: c) 6
What is the approximate sensitivity of ultrasonography for identifying meniscal injuries compared to arthroscopic findings?
a) 65%
b) 70%
c) 79%
d) 85%
Answer: c) 79%
The apophyseal-epiphyseal physis of the tibial tuberosity closes at what age?
a) 6 to 9 months
b) 9 to 12 months
c) 12 to 15 months
d) 15 to 18 months
Answer: b) 9 to 12 months
The lateral femorotibial compartment (LFT) has a volume of approximately how many mL?
a) 51.67 mL ± 2.89 mL
b) 61.67 mL ± 2.89 mL
c) 71.67 mL ± 5.77 mL
d) 81.67 mL ± 5.77 mL
Answer: b) 61.67 mL ± 2.89 mL
How long is the distal femoral physis open in horses?
a) 12 to 18 months
b) 18 to 24 months
c) 24 to 30 months
d) 30 to 36 months
Answer: c) 24 to 30 months
What is the maximum degree of external rotation the tibia undergoes during the screw home mechanism?
a) 5 degrees
b) 6 degrees
c) 8 degrees
d) 10 degrees
Answer: c) 8 degrees
What is the false positive rate of ultrasonography for identifying meniscal injuries compared to arthroscopic findings?
a) 30%
b) 40%
c) 56%
d) 70%
Answer: c) 56%
At what angle should the x-ray beam be directed for the caudocranial view of the stifle?
a) 0 to 10 degrees
b) 10 to 20 degrees
c) 20 to 30 degrees
d) 30 to 40 degrees
Answer: b) 10 to 20 degrees
What is the volume of the medial femorotibial compartment (MFT) of the stifle joint?
A) 41.67 mL ±5.77 mL
B) 61.67 mL ±2.89 mL
C) 50.00 mL ±4.00 mL
D) 30.00 mL ±3.00 mL
Answer: A) 41.67 mL ±5.77 mL
The standing femorotibial joint angle is approximately:
A) 140 degrees
B) 150 degrees
C) 160 degrees
D) 180 degrees
Answer: B) 150 degrees
What percentage of horses typically show communication between the femoropatellar joint (FP) and the medial femorotibial joint (MFT)?
A) 30% to 40%
B) 50% to 55%
C) 60% to 65%
D) 70% to 75%
Answer: C) 60% to 65%
How much mepivacaine diffusion occurs from the lateral femorotibial joint (LFT) to the femoropatellar joint (FP)?
A) 80%
B) 85%
C) 90%
D) 100%
Answer: C) 90%
What ligament is NOT part of the stifle joint’s supporting soft tissue structures?
A) Cranial cruciate ligament
B) Medial femoropatellar ligament
C) Radial collateral ligament
D) Lateral collateral ligament
Answer: C) Radial collateral ligament
The presence of upward fixation of the patella is indicated by:
A) Inability to extend the stifle
B) Inability to flex the stifle
C) Reduced weight bearing
D) Increased gait abnormalities
Answer: B) Inability to flex the stifle
Which imaging technique is particularly beneficial for evaluating obscured regions of the stifle?
A) Radiography
B) Ultrasonography
C) Computed tomography (CT)
D) Nuclear scintigraphy
Answer: B) Ultrasonography
The sensitivity and specificity of ultrasonography for identifying meniscal injuries when compared to arthroscopic findings is:
A) 50% sensitivity, 70% specificity
B) 79% sensitivity, 56% specificity
C) 85% sensitivity, 90% specificity
D) 100% sensitivity, 100% specificity
Answer: B) 79% sensitivity, 56% specificity
The primary purpose of intraarticular anesthesia in stifle diagnostics is to:
A) Provide pain relief
B) Localize lameness
C) Enhance imaging quality
D) Decrease joint swelling
Answer: B) Localize lameness
How many centers of ossification does the stifle of the horse have at birth?
A) Four
B) Five
C) Six
D) Seven
Answer: C) Six
What is the main diagnostic advantage of using CT arthrography over other techniques?
A) It is the least invasive
B) It offers superior identification of soft tissue injuries
C) It provides detailed visualization of bone and cartilage injuries
D) It is the fastest imaging technique
Answer: C) It provides detailed visualization of bone and cartilage injuries
What anatomical feature allows for the “screw home mechanism” in the equine stifle?
A) The shape of the patella
B) The interaction of cruciate and collateral ligaments
C) The thickness of the menisci
D) The size of the femoral condyles
Answer: B) The interaction of cruciate and collateral ligaments
The cranial pouch of the lateral femorotibial compartment contains which anatomical structure?
A) Patellar ligament
B) Peroneus tertius tendon
C) Cranial cruciate ligament
D) Medial meniscus
Answer: B) Peroneus tertius tendon
The volume of the lateral femorotibial compartment (LFT) is approximately:
A) 30.00 mL ±1.00 mL
B) 41.67 mL ±5.77 mL
C) 50.00 mL ±2.00 mL
D) 61.67 mL ±2.89 mL
Answer: D) 61.67 mL ±2.89 mL
Which imaging technique is considered unreliable for detecting soft tissue injuries in the stifle?
A) CT
B) MRI
C) Nuclear scintigraphy
D) Ultrasonography
Answer: C) Nuclear scintigraphy
What anatomical structure is the primary site for identifying cartilage lesions in the stifle using radiography?
A) Medial femoral condyle
B) Lateral trochlear ridge
C) Patella
D) Tibial tuberosity
Answer: A) Medial femoral condyle
The cranial meniscotibial ligament is best visualized in which imaging modality?
A) MRI
B) Radiography
C) Ultrasonography
D) Nuclear scintigraphy
Answer: A) MRI
The cranial cruciate ligament can be assessed through which of the following tests?
A) Tarsal flexion test
B) Stifle flexion test
C) Patellar reflex test
D) Cranial drawer test
Answer: D) Cranial drawer test
What happens to the tibia during the “screw home mechanism”?
A) It undergoes internal rotation
B) It undergoes external rotation
C) It locks into extension
D) It flexes more than normal
Answer: B) It undergoes external rotation
What is the best view to obtain for demonstrating medial femoral condyle cysts?
A) Caudocranial view
B) Lateral view
C) Skyline view
D) Oblique view
Answer: A) Caudocranial view
At what age is the patella fully ossified in horses?
A) 2 months
B) 4 months
C) 6 months
D) 12 months
Answer: B) 4 months
Which of the following is a common indicator of stifle lameness?
A) Increased flexion of the hock
B) Shortened anterior phase of stride
C) High stepping gait
D) Increased toe wear on the contralateral limb
Answer: B) Shortened anterior phase of stride
What anatomical structure primarily contributes to the passive stay apparatus of the hindlimb?
A) Medial meniscus
B) Patellar ligament
C) Trochlear ridges
D) Femorotibial joint
Answer: B) Patellar ligament
What is the primary disadvantage of using ultrasonography in stifle diagnostics?
A) High cost
B) Limited resolution of deep structures
C) Difficulty in visualizing soft tissues
D) Operator-dependent accuracy
Answer: B) Limited resolution of deep structures
The medial and lateral femoropatellar ligaments are important for:
A) Stabilizing the femoropatellar joint
B) Enhancing joint mobility
C) Allowing for patellar movement
D) All of the above
Answer: A) Stabilizing the femoropatellar joint
What is the role of the menisci in the stifle joint?
A) Provide cushioning between femur and tibia
B) Facilitate blood flow to the joint
C) Assist in synovial fluid production
D) Stabilize the patella
Answer: A) Provide cushioning between femur and tibia
Which anatomical structure connects the lateral femoral condyle to the tibia?
A) Medial collateral ligament
B) Lateral collateral ligament
C) Cranial cruciate ligament
D) Patellar tendon
Answer: B) Lateral collateral ligament
What is the primary indicator of stifle joint effusion on physical examination?
A) Increased temperature of the joint
B) Decreased range of motion
C) Swelling around the joint
D) Increased sensitivity to palpation
Answer: C) Swelling around the joint
What is the significance of the patellar locking mechanism?
A) It allows for weight-bearing without muscle contraction
B) It improves blood circulation to the joint
C) It enhances flexibility of the stifle joint
D) It prevents patellar dislocation
Answer: A) It allows for weight-bearing without muscle contraction
The presence of a “flipped” lateral meniscus indicates which type of injury?
A) Meniscal tear
B) Ligament rupture
C) Cartilage damage
D) Synovitis
Answer: A) Meniscal tear
Which joint compartment is the most commonly affected by osteochondritis dissecans in horses?
A) Femoropatellar joint
B) Lateral femorotibial joint
C) Medial femorotibial joint
D) All compartments equally
Answer: A) Femoropatellar joint
What technique is commonly used to obtain synovial fluid from the stifle joint for analysis?
A) Arthroscopy
B) Ultrasound-guided injection
C) Needle aspiration
D) Open surgical biopsy
Answer: C) Needle aspiration
In a horse with stifle lameness, which clinical sign would NOT typically be observed?
A) Focal swelling around the stifle
B) Asymmetry between limbs
C) Decreased range of motion
D) Excessive joint extension
Answer: D) Excessive joint extension
What does a positive cranial drawer sign indicate?
A) Meniscal injury
B) Rupture of the cranial cruciate ligament
C) Patellar luxation
D) Joint effusion
Answer: B) Rupture of the cranial cruciate ligament
Which imaging modality is least useful for assessing soft tissue injuries in the stifle?
A) Radiography
B) MRI
C) Ultrasonography
D) CT
Answer: A) Radiography
What is a common complication of stifle joint injections?
A) Joint effusion
B) Infection
C) Synovitis
D) Cartilage damage
Answer: B) Infection
Which stifle injury is often characterized by sudden onset of severe lameness?
A) Osteoarthritis
B) Meniscal tear
C) Ligament rupture
D) Tendonitis
Answer: C) Ligament rupture
What is the function of the peroneus tertius muscle?
A) Flexion of the stifle
B) Extension of the hock
C) Stabilization of the patella
D) Flexion of the hock
Answer: B) Extension of the hock
What is the most common reason arthroscopy is performed on the equine stifle?
A) Treatment of fractures
B) Removal of foreign bodies
C) Treatment of osteochondrosis
D) Ligament repair
C) Treatment of osteochondrosis
Which type of stifle joint effusion is more commonly associated with acute injury?
A) Chronic effusion
B) Hemarthrosis
C) Synovitis
D) Lymphatic effusion
Answer: B) Hemarthrosis
Which joint compartment remains inaccessible during arthroscopy due to intact collateral and cruciate ligaments?
A) Patellar joint
B) Tibial condyles
C) Femorotibial joint
D) Menisci
Answer: B) Tibial condyles
What percentage of stifle angle is generally used when the femoropatellar joint is in full extension during arthroscopy?
A) 90%
B) 120%
C) 150%
D) 200%
Answer: C) 150%
Which of the following drugs is used preoperatively to decrease lameness and heart rate?
A) Morphine and ketamine
B) Morphine and detomidine
C) Lidocaine and bupivacaine
D) Butorphanol and detomidine
Answer: B) Morphine and detomidine
Hand walking is recommended how long after surgery to reduce swelling?
A) 6 hours
B) 12 hours
C) 24 hours
D) 48 hours
Answer: C) 24 hours
How many synovial compartments are explored in a complete arthroscopic examination of the equine stifle?
A) 2
B) 4
C) 6
D) 8
Answer: C) 6
Figure 101-1. Anatomy of the equine stifle, cranial view, showing: a, parapatellar fibrocartilage; b, medial patellar ligament; c, medial collateral ligament; d, tibial tuberosity; e, cut stump of the biceps femoris muscle; f, middle patellar ligament; g, lateral patellar ligament; h, lateral collateral ligament; i and k, medial and lateral condyles of the tibia.
Figure 101-3. Fluoroscopic image of the LFT of an equine cadaver stifle after injection of positive contrast medium into the caudal pouch of the LFT showing distention of the proximal pocket of the caudal pouch (CP) of the LFT, the distal extension of the LFT called the subextensor recess located in the sulcus muscularis (SM), and the distal pocket of the caudal pouch of the LFT (arrows).
Figure 101-5. Cruciate ligament test used to detect rupture. The shoulder is placed against the back of the limb and the tibia is pulled caudad and released.
Figure 101-2. Anatomy of the equine stifle, lateral view, showing: a, femoropatellar joint (FP); b, middle patellar ligament; c, medial patellar ligament; d, cut stump of the lateral patellar ligament; e, long digital extensor muscle; f, lateral femoropatellar ligament; g, popliteus muscle; h, lateral tibial condyle; i, lateral digital extensor muscle.
Figure 101-4. Appearance of bilateral FP effusion
Figure 101-7. A caudal 30-degree lateral craniomedial oblique radiographic view of the stifle highlights an osteochondrosis lesion (arrow) of the lateral trochlear ridge of the femur.
Figure 101-6. An avulsion fracture (arrow) is evident on this lateromedial stifle radiograph. The avulsed osseous fragment is evident near the distal insertion of the cranial cruciate ligament on the central intercondylar area located just lateral to the medial intercondylar eminence of the tibia (MICET). Avulsion fractures in this area can be from the cranial meniscotibial ligaments or the cranial cruciate ligament insertion sites and cannot be definitively differentiated on x-rays.
Figure 101-8. A caudocranial view of the stifle demonstrating a large subchondral bone cyst (arrows) in the medial femoral condyle.
Figure 101-9. Cranioproximal craniodistal oblique radiographic view (skyline) of the equine stifle, which is used to evaluate the patella, intertrochanteric groove of the femur, and trochlear ridges. Note the sagittal fracture of the medial aspect of the patella (arrow).
Figure 101-10. A transverse CT image section of an equine cadaveric distal femur and patella at the level of the proximal aspect of the medial and lateral femoral condyles. Injection of the caudal pouches of the femorotibial joints with shaving cream prior to imaging shows the extent of distention of these pouches. The popliteal artery and vein (arrow) run in the septum separating the caudal pouches. L, Lateral femoral condyle; M, medial femoral condyle. (
Figure 101-11. A T1-weighted VIBE magnetic resonance image of the stifle in the dorsal plane revealed a large area of bone edema, high signal (with contrast enhancement) in the subchondral bone, and extensive cartilage injury in the lateral femoral condyle (arrow) that was not evident on routine radiographs.
All compartments are observed in arthroscopy in dorsal recumbency with flexed limb wih exception of which joint compartement?
For all approaches, the stifle is placed at 90 to 100 degrees stifle angle, except for the femoropatellar joint, which is best completed in full extension (~150 degrees stifle angle), or with a slight flexion.
Each of the two femorotibial joint compartments is divided into
cranial and caudal pouches
The caudal pouch of the LFT is divided into proximal and distal pockets by
the popliteal tendon
Name the compartments of the stifle that can be evaluated
compartments can be explored:
* The FP
* The cranial pouch of the MFT
* The caudal pouch of the MFT
* The cranial pouch of the LFT
* The proximal pocket of the caudal pouch of the LFT
* The distal pocket of the caudal pouch of the LFT
what is the most common reason for FP arthroscopic exploration?
for evaluation and débridement of osteochondritis disscecans (OCD) lesions of the lateral trochlear ridges
describe the portals for the FP joint
The standard approach to the joint involves creation of a skin portal halfway between the middle and lateral patellar ligaments and halfway between the tibial crest and the distal aspect of the patella. A stab incision is made through the skin, subcutaneous tissue, and the deep fascia of the femoropatellar fat pad. Without prior joint distention, an arthroscopic cannula containing a blunt obturator is advanced through the incision and then in a 45-degree angle to skin in a proximal direction. The cannula/obturator are gently manipulated through the joint capsule up into the space under the patella and over the femoral trochlea, and then the arthroscope is inserted to evaluate the joint. Minimal movement of the scope is recommended until distension of the joint is achieved.
what structures can be observed in the FP arthroscopy?
Sequential examination of the FP includes evaluation along the entire length of both the medial and lateral trochlear ridges, the articulating surface of the patella, the attachments of the patellar ligaments onto the patella, and the suprapatellar pouch.
What should you avoid when performing the instrument portal in the FP joint?
instrument portal placement is completed with spinal needle guidance to obtain an optimal location for débridement of the specific lesion encountered. If the instrument portal is made too far lateral to the lateral patellar ligament, it may be difficult to manipulate the instrument to operate effectively on lesions of the lateral trochlear ridge.
The FP may be entered with the intent to evaluate that joint and then proceed on to evaluation of the cranial pouches of the medial and lateral femorotibial joints through the FP, which has been described as the (name the tx)
“cranial arthroscopic approach to the stifle”
for cranial arthroscopic approach what should you consider when performing the portal for arthrosocope, refer the exact point
it is recommended to place the arthroscope portal 2 cm distal to the patella between the medial and middle patellar
ligaments
what is the ideal surgical approach to the suprapatellar pouch?
Optimal portal placement is 2 cm proximal to the patellar base, and approximately 10 cm lateral to the longitudinal patellar axis in the intermuscular septum between the biceps femoris and vastus lateralis muscles. lateral instrument portal can be made cranioproximally to the previous portal or cranially along the longitudinal axis of the patella in the most proximal aspect of the pouch.
Figure 101-12. (A) A sagittal PD-weighted MR-image through the stifle demonstrating a grade III tear of the medial meniscus (arrow). (B) A transverse T2-weighted MR-image through the stifle at the level of the menisci showing an injury of the cranial meniscotibial ligament of the medial meniscus (arrow).
medial pportals are not recommended in suprapatellar pouch, why?
Medial portals are not recommended because of decreased maneuverability from abdominal interference, thick musculature at the site, and the risk of damage to major nerves and vessels
Cranial pouch of the medial femorotibial compartment what are the arthroscopic approaches?
3 most common approaches:
cranial approach
cranial approach of MFT through FP
lateral approach
mention the landmarks for lateral approach of the MFT joint
For the lateral approach to the cranial pouch of the MFT, the arthroscope portal is located caudal to the lateral patellar ligament, cranial to the long digital extensor tendon, and 2 cm proximal to the tibial crest with the stifle joint at 90 degrees. With a No. 11 blade, the portal is made through the skin and the deep fascia. Using a blunt obturator, the arthroscopic cannula is directed medially and slightly caudally to penetrate the synovial membrane in the axial aspect of the MFT.
mention the landmarks for cranial approach of the MFT joint
For the cranial approach to the cranial pouch of the MFT, the arthroscope portal is located between the middle and medial patellar ligaments about 2 cm proximal to the tibial crest. With a No. 11 blade, the portal is made through the skin and the deep fascia. Using a blunt obturator, the arthroscopic cannula is directed through the fat pad and in a slightly proximal, caudad, and axial direction, until the synovial membrane is penetrated.
mention the landmarks for cranial approach through FP also known as “cranial arthroscopic approach to the stifle” of the MFT joint
has been described as the “cranial arthroscopic approach to the stifle,” involves placing the arthroscope in the FP, with secondary entry into the cranial pouch of the MFT (and/or LFT), using arthroscopic hook scissors to incise the synovial fold at the distal end of the trochlear ridges (Figure 101-13). Specifically, with the stifle joint mildly flexed (~120-degree stifle angle), the FP is entered as described earlier, with the arthroscope portal placed 2 cm distal to the distal aspect of the patella and 2 cm medial to the middle patellar ligament. Following examination of the FP, an instrument portal is created in the FP 2 cm lateral to the middle patellar ligament, at the same level as the first arthroscopic portal. Arthroscopic hook scissors are introduced through this portal and are used to elevate and cut the slit-like synovial membrane identified overlying the cranial and distal aspects of the medial femoral trochlear ridge (Figure 101-14, A). The arthroscope is then advanced through the slit into the MFT (see Figure 101-14, B).
Figure 101-13. The arthroscopic approach to the cranial pouch of the MFT through the FP. In image A (lateral view) the arthroscope and hook scissors are drawn in the appropriate intraoperative positions, with the skin portals placed close to the distal border of the patella. In image B (cranial view) the arthroscope and hook scissors are shown bisecting the synovium into the MFT at the distal aspect of the medial trochlear ridge. The dotted lines represent the medial, middle, and lateral patellar ligaments.
Is prior distension of the MFT necessary before arthroscope placement?
Generally not necessary.
Where is the arthroscope portal located in the lateral approach to the cranial pouch of the MFT?
Caudal to the lateral patellar ligament, cranial to the long digital extensor tendon, and 2 cm proximal to the tibial crest.
What blade is used to create the portal in the lateral approach of MFT joint?
A No. 11 blade.
What is the direction of the arthroscopic cannula insertion in the lateral approach of MFT joint?
Medially and slightly caudally.
In the cranial approach to the cranial pouch of the MFT, where is the portal located?
Between the middle and medial patellar ligaments, 2 cm proximal to the tibial crest.
What tissue does the cannula pass through in the cranial approach?
The fat pad.
What is the purpose of the FP approach in the cranial pouch of the MFT?
It allows access to the cranial pouch of the MFT (and/or LFT) with a single arthroscope portal.
Where is the arthroscope portal located in the FP approach?
2 cm distal to the distal aspect of the patella and 2 cm medial to the middle patellar ligament.
What tool is used to incise the synovial fold in the FP approach?
Arthroscopic hook scissors
What happens if the synovial membrane is thickened in chronic joint disease?
Hook scissors may be ineffective, and an arthroscopic scalpel is used instead.
What joint angle is recommended for better visualization in the FP approach?
A 150-degree stifle angle.
Where is the instrument portal generally placed with all approaches of MFT joint?
Between the medial and middle patellar ligaments.
What structures are evaluated in the cranial pouch of the MFT?
Cranial meniscotibial ligament, medial meniscus, tibial condyle, and femoral condyle.
How is the caudal cruciate ligament observed in these approaches of MFT joint?
Through the synovial membrane.
Why might the lateral approach to the MFT joint be preferred by some surgeons?
It allows easier arthroscope placement and better visualization of the medial femoral condyle and medial meniscus.
What benefit does the FP approach provide for compartment evaluation?
It permits evaluation of all three stifle compartments from a single portal.
How does the FP approach reduce the risk of meniscal damage?
By providing controlled and atraumatic entry, minimizing blind obturator insertion.
What view is particularly enhanced with the The approach to the cranial pouch of the MFT through the FP approach?
The view of the caudal cruciate ligament.
What precaution is advised during curettage of medial femoral condylar cysts in the cranial approach?
Avoid letting debris fall into the FP + lavage of supra patellar pouch
What complication is associated with synovial sepsis in the cranial approach?
In cases of synovial sepsis, the cranial approach eliminates the natural synovial barriers between compartments, and care should be taken to avoid contaminating compartments that are not already affected
why cranial approach is beneficial for sepsis of LFT joint?
access to the distal synovial extension of the LFT (the subextensor recess located in the sulcus muscularis), a common location of fibrin and debris accumulation, is improved.
Figure 101-14. The arthroscopic approach to the cranial pouch of the MFT through the FP. (A) Arthroscopic view of the hook scissors engaging the synovium over the cranial and distal aspect of the medial trochlear ridge of the femur. (B) Arthroscopic view of the transected synovium located over the cranial and distal aspect of the medial trochlear ridge of the femur and the proximal medial femoral condyle. The arthroscope is advanced through the opening to enter the MFT.
Figure 101-15. (A) Arthroscopic view of the cranial pouch of the MFT as viewed from the lateral approach showing the medial femoral condyle (FC), the medial meniscus (M), and the tibial condyle (TC). (B) A probe can be used to elevate the cranial pole of the meniscus and meniscotibial ligament, exposing parts of the medial tibial condyle.
What is the location of the subextensor recess in relation to the LFT?
In the sulcus muscularis.
What anatomical structure can be inadvertently damaged with blind obturator insertion?
The meniscus.
What direction is the arthroscope directed in the cranial approach of MFT joint?
Slightly proximal, caudad, and axial.
What is the joint angle for examining the caudal pouch of the MFT in dorsal recumbency?
Approximately 90 degrees.
What aids in confirming adequate portal placement in the caudal MFT approach?
Spinal needle placement and joint distension.
Where is the portal placed for the caudal pouch of the MFT?
1 cm proximal and parallel to a line from the tibial crest to the medial condyle, and 3 cm caudal to the medial collateral ligament.
What structures are visible in the caudal pouch of the MFT approach?
The caudal aspect of the medial femoral condyle and proximal medial meniscus.
How is the caudal cruciate ligament located in the caudal MFT pouch?
It is located extrasynovially and can be found with a probe through the synovial lining.
What is a benefit of the more caudal MFT approach?
It provides better visualization of the axial medial meniscus and caudal cruciate ligament.
What does the cranial intercondylar approach examine?
The axial caudal MFT, including the caudal cruciate ligament and medial meniscotibial ligament.
Where is the cranial intercondylar approach portal located?
Between the medial and middle patellar ligaments with the stifle flexed at 90–100 degrees.
what is the purpose of the smooth-shafted conical obturator in the cranial intercondylar approach?
To guide the cannula visually into the intercondylar space.
Figure 101-16. Schematic representation of the arthroscopic portals used to explore the caudal pouches of the MFT and LFT. a, The portal to the proximal pocket of the lateral caudal pouch is located at the level of the lateral femoral condyle, 2.5 cm proximal to the distal level of the lateral meniscus and 3 cm caudal to the lateral collateral ligaments; b, the portal to the distal pocket of the lateral caudal pouch is located at the level of the lateral meniscus, through the popliteal tendon, 1.5 cm caudal to the lateral collateral ligament; c, the medial portal is located at the level of the medial femoral condyle, 1 cm proximal to the distal level of the medial meniscus and 3 cm caudal to the medial collateral ligame
What complication may arise from puncturing the caudal joint capsule in the MFT?
Scoring of the medial femoral condyle.
Figure 101-17. Arthroscopic view of the caudal pouch of the MFT of the stifle showing the medial femoral condyle (M), the medial meniscus (MM), and a probe placed on the caudal cruciate ligament (Cr) located behind the synovial membrane.
What steps are taken when using the cranial MFT incision to enter the cranial LFT?
The synovial septum cranial to the intercondylar eminence is identified, and the arthroscope sbustituted by canula/obturator and inserted caudolaterally behind the long digital extensor tendon to the far side of the joint
What joint angle is used for the cranial pouch of the LFT?
Approximately 90 degrees (or 90–120 degrees for FP approach).
what are the three approaches to arthroscopy of the cranial pouch of the LFT?
Replacement of the scope in the LFT after MFT evaluation, medial approach, and FP approach.
describe the landmarks for medial approach to the cranial pouch of LFT
For the medial approach to the cranial pouch of the LFT, the arthroscope portal is best located 2 cm proximal to the tibial crest, midway between the medial and middle patellar ligaments. The arthroscope is directed caudolaterally to enter the LFT. Prior distension of the LFT with saline appears beneficial with this approach.
describe the landmarks for FP approach to the cranial pouch of LFT
placed in dorsal recumbency with the stifle joint maintained at full extension The standard approach to the joint involves creation of a skin portal halfway between the middle and lateral patellar ligaments and halfway between the tibial crest and the distal aspect of the patella. A stab incision is made through the skin, subcutaneous tissue, and the deep fascia of the femoropatellar fat pad. Without prior joint distention, an arthroscopic cannula containing a blunt obturator is advanced through the incision and then in a 45-degree angle to skin in a proximal direction. The cannula/obturator are gently manipulated through the joint capsule up into the space under the patella and over the femoral trochlea, and then the arthroscope is inserted to evaluate the joint.
because the arthroscope does not need to be removed from its medial position to be driven into the LFT after the incision is made with the hook scissors at the distal end of the lateral trochlear ridge. Improved exploration of the distal extension of the LFT, the subextensor recess containing the long digital extensor tendon, and peroneus tertius is achieved with the cranial approach.
can you see the cranial cruciate ligament upon arthro exam of the cranial pouch of LFT?
yes the cranial cruciate ligament is seen lying extrasynovially within medium septum
name the structures visible in the cranial pouch of LFT joint
- Lateral femoral condyle
- laretal tibia condyle
- cranial cruciate ligament extraynovially within the septum
- cranial lateral meniscotibial ligament
lateral - lateral trochlear ridge
the cranial approach to the LFT is best to evaluate which structures?
distal extension of the LFT,
the subextensor recess containing
the long digital extensor tendon,
peroneus tertius is achieved with the cranial approach
the opening into the distal synovial diverticulum of the long digital extensor tendon and peroneus tertius (subextensor recess) can only be accessed by which approach?
cranial approach
How is the horse positioned for examination of the caudal pouch of the MFT?
In dorsal recumbency with the stifle at approximately 90 degrees.
Where is the arthroscope portal located in the caudal pouch of the MFT approach?
1 cm proximal to a line from the tibial crest to the medial tibial condyle, and 3 cm caudal to the medial collateral ligament.
Where is the caudal cruciate ligament located in this approach?
Extrasynovially, accessible through the synovial lining with a probe.
Why is spinal needle placement helpful in the caudal pouch of the MFT?
It helps confirm adequate portal location and trajectory for cannula/obturator placement.
What structures can be examined in the caudal pouch of the MFT?
The caudal aspect of the medial femoral condyle and the proximal medial meniscus.
What alternative approach allows better visualization of the caudal MFT?
A more caudal approach 6-8 cm caudal to the medial collateral ligament. 1-2 cm cranial to the medial saphenous vein and cranioproximal to the palpable gracilis muscle
What key anatomical landmark assists in locating the more caudal MFT portal?
The medial saphenous vein.
Why might the cranial intercondylar approach be used in the MFT?
For enhanced visualization of the medial femoral condyle’s axial aspect and caudal cruciate ligament.
how many surgical approach are described for the caudal pouch of the MFT?
- caudal approach (1cm proximal to the tibia 3 cm caudal to the medial colat lig)
- second more caudal approach 6 to 8 cm caudal to the medial collateral ligament
- cranial intercondylar approach
What degree of stifle flexion is used in the cranial intercondylar approach?
90-100 degrees.
Where is the portal placed in the cranial intercondylar approach to the MFT?
Between the medial and middle patellar ligaments.
How is the second portal located in the cranial intercondylar approach?
By visually guiding a spinal needle into the intercondylar space between the caudal cruciate ligament and medial femoral condyle.
if you want to visualize the caudal axial aspect of the medial femoral condyle, the caudal cruciate ligament, and the caudal medial meniscotibial ligament of the caudal MFT what approach should you use?
cranial intercondylar approach
describe the surgical procedure of the cranial intercondylar approach
With the stifle flexed at 90 to 100 degrees, the scope is inserted with the portal placed between the medial and middle patellar ligaments
The location of a second arthroscopic portal is then determined by visualization of a spinal needle advancing into the intercondylar space between the caudal cruciate ligament and medial femoral condyle from just proximal and caudal to the intercondylar eminence. The site of the portal is generally just lateral to the middle patellar ligament, 50% to 60% of the distance from the tibial crest to the patella. A smooth-shafted conical obturator is visually guided as described earlier for the spinal needle, and the arthroscope canula is placed over the obturator. Puncture of the caudal joint capsule, scoring of the medial femoral condyle in the intercondylar space, and periarticular fluid accumulation are frequently encountered, though of little apparent clinical significance. A caudomedial instrument portal can be created as described earlier for débridement of lesions
What are the artroscopic approachs for the LFT cranial pouch?
- replacement of the scope in the LFT after evaluation of MFT on cranial approach
- medial approach
- approach through the FP
All approach are done 90 degree joint angle
What alternative angle can the stifle be positioned for the FP approach to the LFT?
90–120 degrees.
During the cranial approach of MFT if you want to use ame incision for LTF the artrhoscope is returned to intercondylaree reference point in MFT, then synovial spetum cranial to intercondylar eminence of tibia and arthro replaced with cannula obturator. Where is the cannula/obturator are inserted in?
canula/obturator assembly is then inserted caudolaterally behind the long digital extensor tendon to the far side of the joint, without prior distension of the LFT, and the arthroscope replaced in the canula.
What structure acts as a landmark for re-entering the cranial pouch of the LFT after examining the MFT?
The intercondylar reference point in the MFT.
What is visualized upon entering the cranial pouch of the LFT?
The cranial cruciate ligament lying extrasynovially within the medium septum.
What anatomical structure limits scope manipulation in the LFT’s cranial pouch?
The smaller size of the cranial pouch compared to the MFT.
What approach is used to explore the subextensor recess of the LFT?
The cranial approach.
Where does fibrin and debris commonly accumulate in the LFT during synovial sepsis?
In the subextensor recess.
How is the horse positioned for evaluation of the caudal pouch of the LFT?
Dorsal recumbency with the stifle at 90 degrees.
Where is the portal located for examining the proximal pocket of the caudal LFT pouch?
2.5 cm proximal and parallel to a line from the tibial crest to the lateral tibial condyle, 3 cm caudal to the lateral collateral ligament.
What effect does lateral tarsal rotation have on the popliteal tendon during LFT caudal pouch examination?
Loosens the popliteal tendon, creating a tunnel for arthroscope insertion.
Insertion of the arthroscope into the tunnel still does permit visualization of the lateral meniscus or of the tibial condyle ?
No, insertion of the arthroscope into the tunnel still does not permit visualization of the lateral meniscus or of the tibial condyle.
Where is the portal for examining the distal pocket of the caudal LFT pouch?
On a line from the tibial crest to the lateral tibial condyle, 1.5 cm caudal to the lateral collateral ligament.
What structure is directly passed by when entering the distal pocket of the LFT?
The popliteal tendon.
What structures can be examined in the distal pocket of the LFT caudal pouch?
Caudal lateral meniscus, lateral femoral and tibial condyles, intraarticular popliteal tendon.
What anatomical structure must be avoided near the lateral collateral ligament during LFT evaluation?
The common peroneal nerve.
Where is the popliteal artery situated in relation to the femoral condyles?
Directly between the medial and lateral femoral condyles on the caudal aspect.
What is the main risk of crossing between pouches in the caudal aspect of the LFT?
Injury to the popliteal artery and vein, major deep blood supply to the stifle.
What new technique allows stifle evaluation in a standing horse?
Diagnostic needle arthroscopy.
describe the landmarks for the examination of the proximal pocket of the caudal pouch of the LFT
is located 2.5 cm proximal and parallel to a line drawn from the tibial crest to the lateral condyle of the tibia, and 3 cm caudal to the lateral collateral ligament (see Figure 101-16).6
describe the landmarks for the examination of the distal pocket of the caudal pouch of the LFT
The arthroscope portal that permits examination of the distal pocket of the caudal pouch of the LFT is located on a line drawn from the tibial crest to the lateral condyle of the tibia and 1.5 cm caudal to the lateral collateral ligament (see Figure 101-16). Entrance at this level is directly through the popliteal tendon, permitting examination of the caudal lateral meniscus, part of the caudal aspects of the lateral femoral and tibial condyles, and the intraarticular portion of the popliteal tendon (Figure 101-18).
What equipment is used in needle arthroscopy?
An 18-gauge, 100-mm disposable arthroscope.
What leg positioning may be used during needle arthroscopy?
The leg may stand on the ground or be held flexed.
What advantage does needle arthroscopy provide over traditional methods?
It avoids general anesthesia, lowers costs, and shortens postoperative recovery.
What is a limitation of needle arthroscopy compared to traditional arthroscopy?
A smaller field of view.
What areas can be evaluated with needle arthroscopy?
All intraarticular structures in the FP, MFT, and LFT, including caudal pouches.
How is the arthroscope introduced into the LFT cranial pouch during the FP approach?
Through an incision made with hook scissors at the lateral trochlear ridge’s distal end.
Figure 101-18. Arthroscopic appearance of the distal pocket of the caudal pouch of the LFT, which permits examination of the caudal aspect of the lateral meniscus (LM), part of the caudal aspect of the lateral femoral condyle (L), and the intraarticular portion of the popliteal
tendon (P).
Figure 101-19. Diagnostic standing arthroscopy using a needle arthroscope, showing the cannula placed in the caudal MFT (From Frisbie DD, Barrett MF, McIlwraith CW. Diagnostic stifle joint arthroscopy using a needle arthroscope in standing horses. Vet Surg 2014;43:12-18. Image courtesy of Vet Surg.
Figure 101-20. Mild (A) and severe (B) cartilage injury to the distal aspect of the medial femoral condyle in two different horses.
