The stifle

Mike Farrell

doi:10.22233/9781910443286.23

The stifle

British Small Animal Veterinary Association , 404 (2018); https://doi.org/10.22233/9781910443286.23

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The stifle

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Author: Mike Farrell
From: BSAVA Manual of Canine and Feline Musculoskeletal Disorders
Item: Chapter 23, pp 404 - 446
DOI: 10.22233/9781910443286.23
Copyright: © 2018 British Small Animal Veterinary Association
Publication Date: November 2018

Abstract

The stifle joint is a complex hinge joint consisting of distinct femorotibial and femoropatellar articulations. This chapter discusses the clinical anatomy, examination, diagnosis and management of a wide range of diseases affecting the stifle. Quick Reference Guide to Imaging Techniques by Thomas W. Maddox. Operative Techniques: Patient preparation for stifle surgery; Lateral parapatellar approach; Medial parapatellar approach; Intra-articular stifle joint inspection; Meniscal inspection, partial meniscectomy and medial meniscal release; Crimped lateral fabellotibial suture; Tibial tuberosity transposition; Recession trochleoplasty; Tibial osteotomy procedures – Editor’s guide.

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Figures

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23.1

Flexed canine stifle joint with the patella luxated medially. 1a = caudolateral band of the cranial cruciate ligament; 1b = craniomedial band of the cranial cruciate ligament 2 = caudal cruciate ligament; 3 = medial meniscus; 4 = lateral meniscus; 5 = long digital extensor tendon; 6 = medial humeral condyle; 7 = tibial tuberosity. © 2018 British Small Animal Veterinary Association

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23.1 Flexed canine stifle joint with the patella luxated medially. 1a = caudolateral band of the cranial cruciate ligament; 1b = craniomedial band of the cranial cruciate ligament 2 = caudal cruciate ligament; 3 = medial meniscus; 4 = lateral meniscus; 5 = long digital extensor tendon; 6 = medial humeral condyle; 7 = tibial tuberosity.

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23.2

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23.2 Positive sit test. Note the abnormal sitting posture of the left hind limb. (Courtesy of Rob Pettitt)

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23.3

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23.3 Placement of the clinician’s knee beneath the pelvic floor frees both hands for examination of a standing dog.

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23.4

Cranial draw test. (a) Landmarks are the patella and lateral fabella for the finger and thumb of the upper hand and the tibial tuberosity and fibular head for the finger and thumb of the lower hand. A cranial force is applied to the tibia with the joint in a neutral position and in 30–60 degrees of flexion to aid in the detection of partial cranial crucial ligament (CCL) ruptures. (b) Cranial draw of 5–10 mm is common after complete CCL rupture in large-breed dogs. The caudolateral band of the CCL is taut when the stifle is in a neutral position but not when the stifle is flexed. Therefore a small amount of draw (<3 mm) with the stifle in flexion is consistent with partial CCL rupture of the craniomedial band. (c) Inappropriate technique frequently results in false-positive cranial draw. The tips of the fingers and thumb must be directly in contact with the bony landmarks. If the fingertips wrap around the landmarks as shown, they tend to apply cranial draw to skin and subcutaneous tissues. These structures displace easily in normal patients. © 2018 British Small Animal Veterinary Association

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23.4 Cranial draw test. (a) Landmarks are the patella and lateral fabella for the finger and thumb of the upper hand and the tibial tuberosity and fibular head for the finger and thumb of the lower hand. A cranial force is applied to the tibia with the joint in a neutral position and in 30–60 degrees of flexion to aid in the detection of partial cranial crucial ligament (CCL) ruptures. (b) Cranial draw of 5–10 mm is common after complete CCL rupture in large-breed dogs. The caudolateral band of the CCL is taut when the stifle is in a neutral position but not when the stifle is flexed. Therefore a small amount of draw (<3 mm) with the stifle in flexion is consistent with partial CCL rupture of the craniomedial band. (c) Inappropriate technique frequently results in false-positive cranial draw. The tips of the fingers and thumb must be directly in contact with the bony landmarks. If the fingertips wrap around the landmarks as shown, they tend to apply cranial draw to skin and subcutaneous tissues. These structures displace easily in normal patients.

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23.5

Tibial compression (cranial tibial thrust) test. (a) The stifle is held in a neutral position by all the fingers of the upper hand except the index finger, which is used to press caudally on the tibial tuberosity. The hock is flexed with the lower hand while the upper hand maintains the same stifle flexion angle. (b) The test mimics the loading conditions that generate tibial thrust. If the tibia thrusts cranially during testing, this is a positive tibial compression test and is diagnostic of cranial cruciate ligament (CCL) insufficiency. The tibial compression test is more difficult to perform correctly than the cranial draw test but is sometimes better tolerated in the conscious patient. It is also useful for distinguishing cranial from caudal ligament ruptures. © 2018 British Small Animal Veterinary Association

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23.5 Tibial compression (cranial tibial thrust) test. (a) The stifle is held in a neutral position by all the fingers of the upper hand except the index finger, which is used to press caudally on the tibial tuberosity. The hock is flexed with the lower hand while the upper hand maintains the same stifle flexion angle. (b) The test mimics the loading conditions that generate tibial thrust. If the tibia thrusts cranially during testing, this is a positive tibial compression test and is diagnostic of cranial cruciate ligament (CCL) insufficiency. The tibial compression test is more difficult to perform correctly than the cranial draw test but is sometimes better tolerated in the conscious patient. It is also useful for distinguishing cranial from caudal ligament ruptures.

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23.6

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23.6 Patient positioning for (a) a mediolateral and (b) a caudocranial view of the stifle.

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23.7

(a) Mediolateral and (b) caudocranial radiographs showing periarticular osteophyte and enthesiophyte formation. Note the reduction in the infrapatellar fat pad size consistent with joint effusion. Periarticular osteophytosis should not be used as a predictor of the degree of cartilage pathology, particularly in dogs with cranial cruciate ligament (CCL) disease in which osteophytes can indicate a response to instability rather than acting as an indicator of the severity of osteoarthritis. (c) An intra-articular tumour (synovial sarcoma) causes impingement of the infrapatellar fat pad (arrowhead) as well as osteolysis of the femur, tibia and patella (arrowed). Ultrasonography can be used to differentiate soft tissue masses from synovial effusion. © 2018 British Small Animal Veterinary Association

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23.7 (a) Mediolateral and (b) caudocranial radiographs showing periarticular osteophyte and enthesiophyte formation. Note the reduction in the infrapatellar fat pad size consistent with joint effusion. Periarticular osteophytosis should not be used as a predictor of the degree of cartilage pathology, particularly in dogs with cranial cruciate ligament (CCL) disease in which osteophytes can indicate a response to instability rather than acting as an indicator of the severity of osteoarthritis. (c) An intra-articular tumour (synovial sarcoma) causes impingement of the infrapatellar fat pad (arrowhead) as well as osteolysis of the femur, tibia and patella (arrowed). Ultrasonography can be used to differentiate soft tissue masses from synovial effusion.

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23.8

Anatomy of the cruciate ligaments. (a) The cranial cruciate ligament dominates the cranial view. (b) The cranial cruciate ligament arises in the medial aspect of the lateral condyle and inserts in the intercondylar region. (c) The caudal cruciate ligament arises from the lateral aspect of the medial condyle and inserts on the caudal aspect of the tibia. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.8 Anatomy of the cruciate ligaments. (a) The cranial cruciate ligament dominates the cranial view. (b) The cranial cruciate ligament arises in the medial aspect of the lateral condyle and inserts in the intercondylar region. (c) The caudal cruciate ligament arises from the lateral aspect of the medial condyle and inserts on the caudal aspect of the tibia. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.9

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23.9 Stifle joint forces and cranial tibial thrust. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.10

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23.10 Anatomy of the medial and lateral menisci. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.11

(a) In a cranial cruciate ligament (CCL) deficient stifle, the medial meniscus becomes the primary restraint against cranial tibial thrust and is prone to injury, particularly in the caudal horn. The blue arrows denote the relative movement of the tibia and femoral condyle; the red arrow indicates the medial meniscus. (b–e) Common medial meniscal injuries: (b) longitudinal tear; (c) bucket-handle tear; (d) transverse tear; and (e) caudal pole avulsion (folding injury). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.11 (a) In a cranial cruciate ligament (CCL) deficient stifle, the medial meniscus becomes the primary restraint against cranial tibial thrust and is prone to injury, particularly in the caudal horn. The blue arrows denote the relative movement of the tibia and femoral condyle; the red arrow indicates the medial meniscus. (b–e) Common medial meniscal injuries: (b) longitudinal tear; (c) bucket-handle tear; (d) transverse tear; and (e) caudal pole avulsion (folding injury). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.12

Palpation of the medial aspect of the stifle often reveals a firm thickening, indicative of periarticular fibrosis, that is commonly termed ‘medial buttress’. Deep palpation using a single digit pressed into the caudomedial aspect of the stifle joint often causes a pain response in dogs with injuries to the caudal horn of the medial meniscus. © 2018 British Small Animal Veterinary Association

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23.12 Palpation of the medial aspect of the stifle often reveals a firm thickening, indicative of periarticular fibrosis, that is commonly termed ‘medial buttress’. Deep palpation using a single digit pressed into the caudomedial aspect of the stifle joint often causes a pain response in dogs with injuries to the caudal horn of the medial meniscus.

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23.14

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23.14 A custom hinged stifle orthosis. (Reproduced with permission from OrthoPets Europe)

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23.16

A lateral fabellotibial suture was used to treat cranial cruciate ligament (CCL) insufficiency in a 6-year-old mixed-breed dog. Lameness did not improve postoperatively. (a) Note the very distal position of the tibial bone tunnel (arrowed). Tension applied to the fabellotibial suture causes non-physiological stifle joint flexion, tibial external rotation and compression of the lateral joint compartment. There was a subsequent meniscal injury diagnosed 4 months postoperatively. (b) Revision surgery involved caudal pole hemimeniscectomy and cranial closing wedge tibial plateau levelling osteotomy (TPLO). Note the correct position of the tibial bone tunnel (arrowed). A fabellotibial suture was used due to overt stifle instability (1.5 cm draw). © 2018 British Small Animal Veterinary Association

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23.16 A lateral fabellotibial suture was used to treat cranial cruciate ligament (CCL) insufficiency in a 6-year-old mixed-breed dog. Lameness did not improve postoperatively. (a) Note the very distal position of the tibial bone tunnel (arrowed). Tension applied to the fabellotibial suture causes non-physiological stifle joint flexion, tibial external rotation and compression of the lateral joint compartment. There was a subsequent meniscal injury diagnosed 4 months postoperatively. (b) Revision surgery involved caudal pole hemimeniscectomy and cranial closing wedge tibial plateau levelling osteotomy (TPLO). Note the correct position of the tibial bone tunnel (arrowed). A fabellotibial suture was used due to overt stifle instability (1.5 cm draw).

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23.17

Multiple variations of tibial tuberosity advancement (TTA) are commercially available. The proposed advantage of these modifications is reduced technical demand compared with standard TTA. In the author’s opinion, creation and advancement of an incomplete osteotomy as shown is technically demanding. This requires meticulous precision in locating the distal extremity of the osteotomy and very patient advancement (this can take >5 minutes). The consequence of suboptimal osteotomy or advancement technique is iatrogenic fracture of the hinge of distal bone. (a) Standard TTA. (b) TTA rapid. (c) TTA2. (d) Modified Maquet Technique using a standard TTA cage. (e) Modified Maquet procedure. (b, Courtesy of Toby Gemmill; e, Courtesy of Orthomed UK) © 2018 British Small Animal Veterinary Association

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23.17 Multiple variations of tibial tuberosity advancement (TTA) are commercially available. The proposed advantage of these modifications is reduced technical demand compared with standard TTA. In the author’s opinion, creation and advancement of an incomplete osteotomy as shown is technically demanding. This requires meticulous precision in locating the distal extremity of the osteotomy and very patient advancement (this can take >5 minutes). The consequence of suboptimal osteotomy or advancement technique is iatrogenic fracture of the hinge of distal bone. (a) Standard TTA. (b) TTA rapid. (c) TTA2. (d) Modified Maquet Technique using a standard TTA cage. (e) Modified Maquet procedure. (b, Courtesy of Toby Gemmill; e, Courtesy of Orthomed UK)

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23.18

Video animation stills showing the principles and technique for (a) extra-capsular stabilization, (b) tibial plateau levelling osteotomy and (c) tibial tuberosity advancement. (Courtesy of the University of Edinburgh, available from http://www.ed.ac.uk/vet/services/cclr © 2018 British Small Animal Veterinary Association

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23.18 Video animation stills showing the principles and technique for (a) extra-capsular stabilization, (b) tibial plateau levelling osteotomy and (c) tibial tuberosity advancement. (Courtesy of the University of Edinburgh, available from http://www.ed.ac.uk/vet/services/cclr

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23.20

Mechanical complications after tibial osteotomy surgeries. (a) This diaphyseal tibial fracture occurred 1 month after a modified Maquet procedure. The fracture propagated from the drill hole at the distal limit of the advancement. (b) Surgical repair using orthogonal locking plate fixation. (c) Tibial tuberosity avulsion fracture diagnosed 4 weeks after tibial tuberosity advancement (TTA). (d) Fibular fracture and ‘rock-back’ of the tibial plateau segment diagnosed 6 weeks after tibial plateau levelling osteotomy (TPLO). © 2018 British Small Animal Veterinary Association

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23.20 Mechanical complications after tibial osteotomy surgeries. (a) This diaphyseal tibial fracture occurred 1 month after a modified Maquet procedure. The fracture propagated from the drill hole at the distal limit of the advancement. (b) Surgical repair using orthogonal locking plate fixation. (c) Tibial tuberosity avulsion fracture diagnosed 4 weeks after tibial tuberosity advancement (TTA). (d) Fibular fracture and ‘rock-back’ of the tibial plateau segment diagnosed 6 weeks after tibial plateau levelling osteotomy (TPLO).

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23.21

(a) Mineralization of the cranial cruciate ligament (CCL) and menisci is common in cats with degenerative CCL disease but can also be seen in clinically normal cats. (b) In the author’s experience, the feline femorofabellar ligament is weaker than the equivalent ligament in dogs, which creates a higher risk of fabellar avulsion after lateral fabellotibial suture placement. A screw and washer have been used in this case to create a femoral anchor point. © 2018 British Small Animal Veterinary Association

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23.21 (a) Mineralization of the cranial cruciate ligament (CCL) and menisci is common in cats with degenerative CCL disease but can also be seen in clinically normal cats. (b) In the author’s experience, the feline femorofabellar ligament is weaker than the equivalent ligament in dogs, which creates a higher risk of fabellar avulsion after lateral fabellotibial suture placement. A screw and washer have been used in this case to create a femoral anchor point.

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23.22

Caudal cruciate ligament rupture occurred secondary to septic arthritis as a late complication after tibial tuberosity advancement (TTA) surgery to treat complete CCL rupture. Note the caudal displacement of the tibial eminences relative to the femoral condyles. © 2018 British Small Animal Veterinary Association

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23.22 Caudal cruciate ligament rupture occurred secondary to septic arthritis as a late complication after tibial tuberosity advancement (TTA) surgery to treat complete CCL rupture. Note the caudal displacement of the tibial eminences relative to the femoral condyles.

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23.23

CT scan showing deformities in a 22-month-old Akita with grade III medial patellar luxation of the right hindlimb (left on the image). Note the distal femoral varus, the medial luxated position of the patella and the internal rotation of the tibia and tibial tuberosity. The left hindlimb (right on the image) has mild distal femoral varus. (Courtesy of Gareth Arthurs) © 2018 British Small Animal Veterinary Association

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23.23 CT scan showing deformities in a 22-month-old Akita with grade III medial patellar luxation of the right hindlimb (left on the image). Note the distal femoral varus, the medial luxated position of the patella and the internal rotation of the tibia and tibial tuberosity. The left hindlimb (right on the image) has mild distal femoral varus. (Courtesy of Gareth Arthurs)

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23.24

(a) Diffuse full-thickness cartilage erosion is present on the medial trochlear ridge of this 2-year-old French Bulldog with grade III medial patellar luxation (MPL) (medial is to the right of the image). (b) A RidgeStop™ implant was used to cover the cartilage defect and increase the height of the medial trochlear ridge. Quadriceps realignment was also performed via tibial tuberosity transposition. © 2018 British Small Animal Veterinary Association

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23.24 (a) Diffuse full-thickness cartilage erosion is present on the medial trochlear ridge of this 2-year-old French Bulldog with grade III medial patellar luxation (MPL) (medial is to the right of the image). (b) A RidgeStop™ implant was used to cover the cartilage defect and increase the height of the medial trochlear ridge. Quadriceps realignment was also performed via tibial tuberosity transposition.

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23.25

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23.25 Distal femoral and proximal tibial osteotomies have been performed to treat excessive distal femoral and proximal tibial varus and torsion.

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23.26

(a) A block recession sulcoplasty had been performed but there was recurrent patellar luxation and almost complete necrosis of the cartilage surface of the osteochondral graft. (b) The trochlea has been resected (K-wires were used for soft tissue retraction) and the base-plate has been screwed into place. (c) The patellar groove prosthesis in situ. © 2018 British Small Animal Veterinary Association

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23.26 (a) A block recession sulcoplasty had been performed but there was recurrent patellar luxation and almost complete necrosis of the cartilage surface of the osteochondral graft. (b) The trochlea has been resected (K-wires were used for soft tissue retraction) and the base-plate has been screwed into place. (c) The patellar groove prosthesis in situ.

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23.27

(a) Mediolateral and (b) caudocranial radiographs showing osteochondrosis of the lateral femoral condyle in a 5-month-old Hungarian Vizsla. Note that marked stifle effusion causes compression of the fat pad (white arrow) as well as the fascial plane caudal to the stifle joint. Flattening of the lateral femoral condyle can be seen on both views (arrowheads) and sclerosis can be seen in the adjacent subchondral bone on the mediolateral view. The black arrow shows the typical location of the extensor fossa that appears as an indentation in the contour of the lateral femoral trochlear ridge and should not be mistaken for an OC lesion. (c) The normal extensor fossa (arrowed) in this 1.5-year-old Newfoundland affected by a partial cranial cruciate ligament (CCL) rupture is very obvious. This appearance is common in giant-breed dogs. © 2018 British Small Animal Veterinary Association

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23.27 (a) Mediolateral and (b) caudocranial radiographs showing osteochondrosis of the lateral femoral condyle in a 5-month-old Hungarian Vizsla. Note that marked stifle effusion causes compression of the fat pad (white arrow) as well as the fascial plane caudal to the stifle joint. Flattening of the lateral femoral condyle can be seen on both views (arrowheads) and sclerosis can be seen in the adjacent subchondral bone on the mediolateral view. The black arrow shows the typical location of the extensor fossa that appears as an indentation in the contour of the lateral femoral trochlear ridge and should not be mistaken for an OC lesion. (c) The normal extensor fossa (arrowed) in this 1.5-year-old Newfoundland affected by a partial cranial cruciate ligament (CCL) rupture is very obvious. This appearance is common in giant-breed dogs.

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23.28

Osteochondral autograft transfer in a 7-month-old Labrador Retriever with osteochondrosis. Note (a) the harvest site in the non-weight-bearing sulcus terminalis of the femoral trochlea and (b) the transposed graft in situ, which should have a surface contour that is continuous with the surrounding cartilage. © 2018 British Small Animal Veterinary Association

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23.28 Osteochondral autograft transfer in a 7-month-old Labrador Retriever with osteochondrosis. Note (a) the harvest site in the non-weight-bearing sulcus terminalis of the femoral trochlea and (b) the transposed graft in situ, which should have a surface contour that is continuous with the surrounding cartilage.

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23.29

(a) Computed tomographic and (b) photographic images of a SynaCart® implant used for resurfacing a medial condylar osteochondrosis lesion. (Courtesy of Noel Fitzpatrick) © 2018 British Small Animal Veterinary Association

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23.29 (a) Computed tomographic and (b) photographic images of a SynaCart® implant used for resurfacing a medial condylar osteochondrosis lesion. (Courtesy of Noel Fitzpatrick)

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23.30

(a) Mediolateral radiograph showing left patellar tendon rupture in a 4-year-old Rhodesian Ridgeback. A penetrating injury had been sustained 10 days previously. Note the patella alta caused by lengthening of the patellar tendon mechanism. (b) The normal stifle joint is shown for comparison. (c) Patellar tendon rupture can be seen in this 1-year-old Labrador Retriever. This mediolateral radiograph was taken 6 weeks after tibial tuberosity transposition. © 2018 British Small Animal Veterinary Association

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23.30 (a) Mediolateral radiograph showing left patellar tendon rupture in a 4-year-old Rhodesian Ridgeback. A penetrating injury had been sustained 10 days previously. Note the patella alta caused by lengthening of the patellar tendon mechanism. (b) The normal stifle joint is shown for comparison. (c) Patellar tendon rupture can be seen in this 1-year-old Labrador Retriever. This mediolateral radiograph was taken 6 weeks after tibial tuberosity transposition.

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23.31

Surgical reconstruction of the patellar tendon (left is medial). (a) The patellar defect was reconstructed and the primary repair has been internally augmented using a hamstring graft. Note the defect in the donor bed along the medial aspect of the tibia (yellow arrow), and the transposed graft sutured to the abaxial borders of the patellar tendon (white arrow). (b) A transarticular external skeletal fixator has been used to protect an internal patellar tendon reconstruction. The four pins transfixing the femur are placed from lateral to medial and the four tibial pins are placed from medial to lateral to maximize the use of safe corridors. © 2018 British Small Animal Veterinary Association

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23.31 Surgical reconstruction of the patellar tendon (left is medial). (a) The patellar defect was reconstructed and the primary repair has been internally augmented using a hamstring graft. Note the defect in the donor bed along the medial aspect of the tibia (yellow arrow), and the transposed graft sutured to the abaxial borders of the patellar tendon (white arrow). (b) A transarticular external skeletal fixator has been used to protect an internal patellar tendon reconstruction. The four pins transfixing the femur are placed from lateral to medial and the four tibial pins are placed from medial to lateral to maximize the use of safe corridors.

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23.32

Mediolateral radiographs of the stifle joint of a 6-year-old Springer Spaniel taken (a) immediately and (b) 6 weeks postoperatively following TTA surgery. Note the severe insertional thickening of the patellar tendon (arrowed). © 2018 British Small Animal Veterinary Association

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23.32 Mediolateral radiographs of the stifle joint of a 6-year-old Springer Spaniel taken (a) immediately and (b) 6 weeks postoperatively following TTA surgery. Note the severe insertional thickening of the patellar tendon (arrowed).

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23.33

(a) Mediolateral and (b) caudocranial radiographs of the stifle of a 2-year-old Domestic Shorthaired cat presenting after unknown trauma with a moderate weight-bearing lameness and plantigrade stance affecting the right pelvic limb. Note the distolateral displacement of the lateral fabella and small fragments of bone. This is pathognomic for lateral gastrocnemius avulsion. (c) Normal fabellar asymmetry in a 10-year-old West Highland White Terrier. (a, b Courtesy of Alex Belch) © 2018 British Small Animal Veterinary Association

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23.33 (a) Mediolateral and (b) caudocranial radiographs of the stifle of a 2-year-old Domestic Shorthaired cat presenting after unknown trauma with a moderate weight-bearing lameness and plantigrade stance affecting the right pelvic limb. Note the distolateral displacement of the lateral fabella and small fragments of bone. This is pathognomic for lateral gastrocnemius avulsion. (c) Normal fabellar asymmetry in a 10-year-old West Highland White Terrier. (a, b Courtesy of Alex Belch)

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23.34

Popliteal muscle avulsion in a 10-month-old Saluki with moderate weight-bearing lameness of the right pelvic limb. (a) Note the lucency distal to a sclerotic line that demarcates the proximal margin of the origin of the popliteal tendon (arrowed). There is also distal displacement of the popliteal sesamoid bone (arrowhead); compare with the (b) normal contralateral limb (arrowed). (c) The caudocranial radiograph shows a lucent defect (arrowed). © 2018 British Small Animal Veterinary Association

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23.34 Popliteal muscle avulsion in a 10-month-old Saluki with moderate weight-bearing lameness of the right pelvic limb. (a) Note the lucency distal to a sclerotic line that demarcates the proximal margin of the origin of the popliteal tendon (arrowed). There is also distal displacement of the popliteal sesamoid bone (arrowhead); compare with the (b) normal contralateral limb (arrowed). (c) The caudocranial radiograph shows a lucent defect (arrowed).

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23.35

(a) The Biomedtrix canine total knee replacement (TKR) is only suitable when the collateral ligaments are intact. (b) This custom-made hinged TKR was used to treat end-stage osteoarthritis secondary to multi-ligamentous instability. (Courtesy of Noel Fitzpatrick) © 2018 British Small Animal Veterinary Association

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23.35 (a) The Biomedtrix canine total knee replacement (TKR) is only suitable when the collateral ligaments are intact. (b) This custom-made hinged TKR was used to treat end-stage osteoarthritis secondary to multi-ligamentous instability. (Courtesy of Noel Fitzpatrick)

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23.36

Mediolateral radiograph showing complete stifle arthrodesis 1.5 years postoperatively in an 8-year-old Domestic Shorthaired cat that had previous unsuccessful surgical reconstruction of a traumatic multi-ligamentous injury. The radiograph shows the cranial plate position and a 120-degree flexion angle. © 2018 British Small Animal Veterinary Association

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23.36 Mediolateral radiograph showing complete stifle arthrodesis 1.5 years postoperatively in an 8-year-old Domestic Shorthaired cat that had previous unsuccessful surgical reconstruction of a traumatic multi-ligamentous injury. The radiograph shows the cranial plate position and a 120-degree flexion angle.

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23.37

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23.37 Patient positioning for a mediolateral view of the stifle. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.38

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23.38 Patient positioning for a caudocranial view of the stifle. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.39

Patient positioning for a stressed caudocranial view of the stifle. Placing ties as shown will stress the lateral aspect of the joint. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.39 Patient positioning for a stressed caudocranial view of the stifle. Placing ties as shown will stress the lateral aspect of the joint. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.40

Multiplanar reconstruction (MPR) CT positive contrast arthrograms of the right stifle of a 10-year-old female Labrador Retriever with late (medial) meniscal injury post tibial plateau levelling osteotomy (TPLO) surgery. Contrast medium is seen filling the region normally occupied by the medial meniscus (crosshairs) and contrasts with the normal lateral meniscal filling defect (solid arrows). Note the metal streak artefacts as a result of the TPLO implants (dashed arrows). © 2018 British Small Animal Veterinary Association

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23.40 Multiplanar reconstruction (MPR) CT positive contrast arthrograms of the right stifle of a 10-year-old female Labrador Retriever with late (medial) meniscal injury post tibial plateau levelling osteotomy (TPLO) surgery. Contrast medium is seen filling the region normally occupied by the medial meniscus (crosshairs) and contrasts with the normal lateral meniscal filling defect (solid arrows). Note the metal streak artefacts as a result of the TPLO implants (dashed arrows).

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23.41

Ultrasonogram of the stifle of a dog. The patella (P) can be seen proximally with some normal patellar tendon (T); more distally near the insertion there is hypoechoic tissue and loss of normal tendon fibre pattern (R), indicating severe pathology (rupture/partial rupture) of the distal part of the tendon. © 2018 British Small Animal Veterinary Association

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23.41 Ultrasonogram of the stifle of a dog. The patella (P) can be seen proximally with some normal patellar tendon (T); more distally near the insertion there is hypoechoic tissue and loss of normal tendon fibre pattern (R), indicating severe pathology (rupture/partial rupture) of the distal part of the tendon.

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23.42

Patient preparation for stifle surgery. (a) Dorsal recumbency allows the best appreciation of limb alignment and facilitates the medial approach to the stifle. (b) Four sterile drapes have been placed (use of adhesive drapes, as in this case, is optional). (c) A piece of sterile drape material, or a sterile glove, can be used to grasp the unsterile foot dressing. This is secured with sterile cohesive bondage material (e.g. Vetrap). (d) A large waterproof drape can be fenestrated and passed over the limb. This is especially useful in operations involving significant surgical site irrigation. © 2018 British Small Animal Veterinary Association

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23.42 Patient preparation for stifle surgery. (a) Dorsal recumbency allows the best appreciation of limb alignment and facilitates the medial approach to the stifle. (b) Four sterile drapes have been placed (use of adhesive drapes, as in this case, is optional). (c) A piece of sterile drape material, or a sterile glove, can be used to grasp the unsterile foot dressing. This is secured with sterile cohesive bondage material (e.g. Vetrap). (d) A large waterproof drape can be fenestrated and passed over the limb. This is especially useful in operations involving significant surgical site irrigation.

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23.43

Lateral parapatellar approach. (a) Incision along the cranial border of the biceps femoris muscle. (b) The biceps femoris muscle and fascia lata are retracted. (c) Retraction of the infrapatellar fat pad exposes the intra-articular structures. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.43 Lateral parapatellar approach. (a) Incision along the cranial border of the biceps femoris muscle. (b) The biceps femoris muscle and fascia lata are retracted. (c) Retraction of the infrapatellar fat pad exposes the intra-articular structures. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.44

Medial parapatellar approach. (a) Incision into the sartorius muscle. (b) Luxation of the patella and stifle flexion exposes the intra-articular structures. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.44 Medial parapatellar approach. (a) Incision into the sartorius muscle. (b) Luxation of the patella and stifle flexion exposes the intra-articular structures. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.45

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23.45 Limited medial approach. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.46

Correct use of Gelpi retractors and stifle distractors. (a) Two sizes of stifle distractors are available (Veterinary Instrumentation) for large- and small-breed dogs, although the large size (a) can be introduced into the stifle joint of small-breed dogs, if the cranial cruciate ligament (CCL) is ruptured. (b) One or two Gelpi retractors are introduced into the joint to expose the femoral trochlear groove and intercondylar notch. The stifle distractors are introduced into the intercondylar fossa from cranial to caudal; they must be fully closed and should be introduced with the tips pointing medially and laterally to minimize the chance of iatrogenic trauma to the cartilage surfaces. The tips should be positioned as caudally as possible to improve distraction of the caudal compartment of the joint. The stifle distractors are rotated through 90 degrees and slowly ratcheted open. Positioning the upper tip more caudally in the intercondylar fossa than the lower tip on the tibial plateau induces cranial translation of the tibia and improves access to the caudal compartment. If access to the caudal compartment of the stifle is suboptimal, a second stifle distractor can be inserted with the jaws positioned deep to the jaws of the first distractor. This provides even distraction of the joint and can significantly improve access for inspection of the caudal poles of the menisci (see Equipment Extras above). © 2018 British Small Animal Veterinary Association

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23.46 Correct use of Gelpi retractors and stifle distractors. (a) Two sizes of stifle distractors are available (Veterinary Instrumentation) for large- and small-breed dogs, although the large size (a) can be introduced into the stifle joint of small-breed dogs, if the cranial cruciate ligament (CCL) is ruptured. (b) One or two Gelpi retractors are introduced into the joint to expose the femoral trochlear groove and intercondylar notch. The stifle distractors are introduced into the intercondylar fossa from cranial to caudal; they must be fully closed and should be introduced with the tips pointing medially and laterally to minimize the chance of iatrogenic trauma to the cartilage surfaces. The tips should be positioned as caudally as possible to improve distraction of the caudal compartment of the joint. The stifle distractors are rotated through 90 degrees and slowly ratcheted open. Positioning the upper tip more caudally in the intercondylar fossa than the lower tip on the tibial plateau induces cranial translation of the tibia and improves access to the caudal compartment. If access to the caudal compartment of the stifle is suboptimal, a second stifle distractor can be inserted with the jaws positioned deep to the jaws of the first distractor. This provides even distraction of the joint and can significantly improve access for inspection of the caudal poles of the menisci (see Equipment Extras above).

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23.47

Partial meniscectomy for a bucket-handle tear. After the caudal attachment is sectioned, a radial cut is made at the cranial extent of the injured section. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.47 Partial meniscectomy for a bucket-handle tear. After the caudal attachment is sectioned, a radial cut is made at the cranial extent of the injured section. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.48

A 2–2.5 mm drill hole is created from medial to lateral starting 5–8 mm caudal to the point of insertion of the patellar tendon (arrowed). The cranial tibial muscle is sharply dissected from cranial to caudal to expose the lateral exit of the tibial bone tunnel. The free end of the suture is passed from medial to lateral through the tibial tunnel. © 2018 British Small Animal Veterinary Association

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23.48 A 2–2.5 mm drill hole is created from medial to lateral starting 5–8 mm caudal to the point of insertion of the patellar tendon (arrowed). The cranial tibial muscle is sharply dissected from cranial to caudal to expose the lateral exit of the tibial bone tunnel. The free end of the suture is passed from medial to lateral through the tibial tunnel.

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23.49

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23.49 Lateral fabellotibial suture with a crimped configuration. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.50

(a) An oscillating saw is used to separate the tibial tuberosity. (b) Tibial tuberosity transposition stabilized with two Kirschner wires and a tension-band wire in a 2.5-year-old Labrador Retriever. There is evidence of a rectangular recession trochleoplasty. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.50 (a) An oscillating saw is used to separate the tibial tuberosity. (b) Tibial tuberosity transposition stabilized with two Kirschner wires and a tension-band wire in a 2.5-year-old Labrador Retriever. There is evidence of a rectangular recession trochleoplasty. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.51

A fine-toothed hard-backed saw blade. This is similar to the X-ACTO saw but is stiffer, resulting in improved handling during recession sulcoplasty. (Courtesy of Veterinary Instrumentation) © 2018 British Small Animal Veterinary Association

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23.51 A fine-toothed hard-backed saw blade. This is similar to the X-ACTO saw but is stiffer, resulting in improved handling during recession sulcoplasty. (Courtesy of Veterinary Instrumentation)

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23.52

Wedge recession trochleoplasty. (a) Following removal of a wedge-shaped section, a parallel cut is made in the opposite side to the direction of patellar luxation. (b) After removal of the second section, the original wedge is replaced. The caudal ridge has been removed to secure a tight fit. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.52 Wedge recession trochleoplasty. (a) Following removal of a wedge-shaped section, a parallel cut is made in the opposite side to the direction of patellar luxation. (b) After removal of the second section, the original wedge is replaced. The caudal ridge has been removed to secure a tight fit. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.53

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23.53 Intraoperative view of a wedge recession trochleoplasty.

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23.54

Block recession trochleoplasty. (a) Parallel incisions in the trochlear ridges, angled at approximately 10 degrees axially. (b) Following resection of cancellous bone, the osteochondral block is replaced. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. © 2018 British Small Animal Veterinary Association

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23.54 Block recession trochleoplasty. (a) Parallel incisions in the trochlear ridges, angled at approximately 10 degrees axially. (b) Following resection of cancellous bone, the osteochondral block is replaced. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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23.55

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23.55 Intraoperative view of a block recession trochleoplasty.

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23.56

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23.56 Preoperative image used for templating of CWO-TPLO surgery; lines to measure the TPA are shown.

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23.57

Postoperative mediolateral radiograph showing the ostectomy site reduced and compressed with implants in situ. Locking implants are used for greater stability. The adjusted TPA can also be calculated from this image. © 2018 British Small Animal Veterinary Association

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23.57 Postoperative mediolateral radiograph showing the ostectomy site reduced and compressed with implants in situ. Locking implants are used for greater stability. The adjusted TPA can also be calculated from this image.

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23.58

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23.58 Mediolateral radiograph of the tibia used to measure TPA and template the radial TPLO.

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23.59

Postoperative mediolateral radiograph showing the tibial osteotomy reduced and compressed with implants in situ. The adjusted TPA can be calculated from this image. © 2018 British Small Animal Veterinary Association

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23.59 Postoperative mediolateral radiograph showing the tibial osteotomy reduced and compressed with implants in situ. The adjusted TPA can be calculated from this image.

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23.60

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23.60 Mediolateral preoperative radiograph for calculation of tibial tuberosity advancement and planning of implant size and position.

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23.61

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23.61 Mediolateral postoperative radiograph showing implant positioning and osteotomy location following a forked Kyon TTA technique.