Robert Botte, DVM, Diplomate ACVS Veterinary Surgical Service San Diego, California. Kyon Symposium 2010 Zurich

Transcription

1 Robert Botte, DVM, Diplomate ACVS Veterinary Surgical Service San Diego, California Kyon Symposium 2010 Zurich

2 ! Special Considerations " Anatomic variation " Precise implant placement " Factors affecting amount of advancement " Use of oversized plates! Complications

3 ! Dogs vary in size! Variation in proximal tibia! Potential complications " Poor osteotomy location " Poor plate placement " Poor cage placement

4 Proximal Tibia Variation! Tibial Tuberosity Length! Insertion Point of Patellar Tendon! Cranial Border (Tibial Crest)! Area proximal to the insertion 11

5 Cranial border variation 37 kg Labrador P7 + C9 45 kg rottweiler P5 + C12

6 Tibial Tuberosity Length 25 kg Staffordshire terrier 33 kg Labrador retriever

7 Need more advancement with short TT length 25 kg Staffordshire terrier 33 kg Labrador retriever

8 Preoperative planning, non-digital radiographs

9 Preoperative planning, digital radiographs Patellar tendon origin Femoral condyle center Tibial condyle center 10 cm K-wire Tracing on clear transparency

10 Standard Use of TTA Drill Guide

11 Measuring Osteotomy Location

12 TTA Plate Used as a Drilling Template

13 Drill most distal fork hole first

14 Visualize all 4 landmarks simultaneously Osteotomy Patellar tendon insertion Distal cranial Border Cranial cortex of tibia

15 Mark location for most proximal fork prong

16 Align drill guide with mark

17 Inspect plate position

18 ! Small dogs! Unusual anatomy! Open physis! Oversized plate

19 Unusual Anatomy Low PT insertion point Short TT length Indistinct cranial border kg German Shepherd Mix

20 Unusual anatomy 25 kg German Shepherd Mix

21 Indistinct vs. Distinct Cranial Border 31 kg Staffordshire terrier 42 kg German shepherd

22 Indistinct vs Distinct Cranial Border Poor plate position Good plate position

23 Indistinct vs Distinct Cranial Border

24 Dealing with Indistinct Cranial Border Adjust plate position or Use new long TTA plate

25 Left leg - 5 hole standard plate Indistinct Cranial Border Right leg 5 hole long plate 31 kg Staffordshire terrier 31 kg Staffordshire terrier

26 Common tangent method to measure amount of advancement 90º Common tangent 12

27 ! Cage taper! Patellar tendon insertion height! Anatomy proximal to patellar tendon insertion! Patellar tendon insertion direction of movement! Proximal displacement of cut segment! Cage location proximodistal

28 Cage Taper 5 mm 7 mm 9 mm Adapted from Lafaver et al. Veterinary Surgery 2007;36:

29 Effect of cage taper and anatomy on advancement + +

30 Anatomic variation proximal to patellar tendon insertion can affect advancement + A A

31 Anatomic variation proximal to patellar tendon insertion can affect advancement +

32 Direction of movement of patellar tendon insertion

33 Patellar tendon insertion moves in a different direction than that measured by the common tangent method

34 Proximal displacement of the cut segment affects advancement

35 Less advancement with no proximal displacement

36 More advancement with proximal displacement

37 ! Limb not fully extended when radiographed! Cage taper and anatomic variation! Direction of patellar tendon insertion movement! Saw kerf

38 Computer simulation to determine the amount of advancement to achieve 90 degrees to common tangent

39 Draw line representing patellar tendon at 90 degrees to common tangent

40 Simulate osteotomy and rotate tibial tuberosity segment

41 Measure X to determine the advancement required to move the patellar tendon 90 degrees to the common tangent

42 ! To increase osteotomy length and cage size! Repair of patellar luxation after TTA! Following broken plate screw

43 Plate and cage combinations Commonly Used Combinations Plate size Cage size 3, 4 hole 6 mm 5, 6 9 mm 6, 7, 8 12 mm 7, 8 15 mm Questionable Combinations Plate size Cage size 4 hole 9 mm 5 12 mm

44 Potential problem with cage too wide and plate too short (osteotomy too short) Potential fracture at lower edge of cage Adapted from Lafaver et al. Veterinary Surgery 2007;36:

45 Complication resulting from P4 + C9? Post TTA 7 week post TTA 30 kg English bulldog

46 Oversized 5 hole plate to accommodate 9 mm cage, fork cut to 4 prongs to avoid P4 + C9. Distal cranial border Distal cranial border 25 kg English bulldog

47 5 hole plate with 4 prong fork

48 ! 6 cases Is a longer osteotomy with an oversized plate warranted? " 3 English bulldog " 1 tibial tuberosity fracture! Needs further study " Is it beneficial? # Should P4 + C9 and P5 + C12 be avoided? " Is it safe? Stress riser/tibia fracture at distal osteotomy?! Alternative new long TTA plate in select cases

49 Less concern about P4 + C9 and P5+C12 with low patellar tendon insertions because of extra osteotomy length proximal to the insertion P5 + C12 42 kg Labrador ret

50 Oversized plate for patellar luxation after TTA healed 33 kg Labrador retriever

51 Patellar luxation after TTA healed osteotomy

52 Tibial tuberosity transposition and oversized plate

53 6 hole plate replaced with 7 hole plate, fork cut to 6 prongs to avoid original plate screw holes

54 Oversized plate after screw head sheared off 31 kg pit bull terrier

55 Major Complications 25 (5.2%)! 5 (1.0%) Septic arthritis! 4 (0.8%) Tibial tuberosity fracture! 4 (0.8%) Subcutaneous infection! 4 (0.8%) Medial patellar luxation! 3 (0.6%) Screw insertion errors! 2 (0.4%) Pivot shift, 1 dog bilateral! 1 (0.2%) Fixation failure! 1 (0.2%) Periosteal reaction proximal tibia! 1 (0.2%) Draining tract

56 Minor Complications 23 (4.7%)! 10 (2.1%) Partial wound dehiscence! 6 (1.2%) Trauma to LDE tendon! 4 (0.8%) Lick granuloma! 3 (0.6%) Minor wound drainage

57 ! 8 (1.6%) Partial wound dehiscence! 5 (1.0%) Septic arthritis! 3 (0.6%) Subcutaneous infection! 3 (0.6)% Lick granuloma! 1 (0.2%) Tibial tuberosity fracture! 1 (0.2%) Fixation failure! 1 (0.2%) Plate removal for draining tract! 1 (0.2 %) Pivot shift! 1 (0.2%) Patellar luxation

58 Key factors to reduce TTA complications include:! Accurate implant placement! Accurate osteotomy location! Sufficient tibial tuberosity advancement

59 QUESTIONS??