pISSN 1598-298X / eISSN 2384-0749J Vet Clin 34(1) : 7-12 (2017)http://dx.doi.org/10.17555/jvc.2017.02.34.1.7

7

Triple Tibial Osteotomy (TTO) for Treatment of

Cranial Cruciate Ligament Rupture in Small Breed Dogs

Tae-Hwan Kim, Subin Hong, Heesup Moon, Jeong-In Shin,

Yun-Sul Jang, Hyeonjong Choi, In-Geun Kim and Jae-hoon Lee1

Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea

(Received: November 23, 2016 / Accepted: February 14, 2017)

Abstract : Twelve dogs weighing less than 10 kg underwent unilateral TTO to stabilize the stifle joint with cranialcruciate ligament rupture. Surgical findings, intra-operative and post-operative complications were recorded.Radiographic examinations were performed for 8 weeks following surgery. Postoperative outcome was evaluated usinga visual analogue lameness scoring system. Mean preoperative PTA (the angle created by the intersection of the tibialplateau extrapolation line and the patellar tendon) was 103.8 degrees. Mean tibial wedge angle was 16.6 degrees. Meanpostoperative PTA was 92.1 degrees. Intraoperatively, fracture through the caudal tibial cortex occurred in all dogs,through the distal tibial crest cortex in 2 dogs, through the lateral tibial cortex in 2 dogs and through the fibula in1 dog. Four-week postoperative radiographs demonstrated evidence of progressive bone union at osteotomy site andcomplete unions were identified at 8 week in 10 dogs. All dogs were healed in 11 weeks. Most of dogs revealedweak lameness in 4 weeks and normal ambulation in 8 weeks postoperatively except for only one dog returned in11 weeks. Despite frequent minor complication, it appears that the TTO is an alternative procedure for managementof cranial cruciate ligament rupture in small breed dogs.

Key words : cranial cruciate ligament, triple tibial osteotomy, complication, small breed, dog.

Introduction

Proximal tibial osteotomy techniques for treatment of

CCLR recently have gained popularity. There are two alter-

nate concepts about how dynamic stabilization should be

attained with proximal tibial osteotomy. The first concept

was suggested by Slocum and Devine (24). This concept was

that the joint reaction force in the stifle during weight bear-

ing was nearly parallel to functional the long axis of the tibia.

Because of the caudo-distally sloping tibial plateau, the shear

forces in the stifle joint accountable for CTT would have a

relationship with the angle formed between the tibial plateau

and functional long axis of the tibia. They suggested that

CTT would be removed from CCL ruptured joint by reduc-

ing the tibial plateau angle (TPA) so that it was perpendicu-

lar to the functional long axis of the tibia. The surgery

techniques to accomplish this purpose were the cranial tibial

wedge osteotomy (CTWO) (25) and the tibial plateau level-

ing osteotomy (TPLO) (26). The second concept is founded

on a biomechanical model suggested by Tepic et al. This

concept was developed from study in human being that the

joint force generated in weight bearing is parallel to patellar

tendon (17). It was therefore suggested that elimination CTT

during weight bearing would be achieved by performing a

tibial tuberosity advancement (TTA), so that the patellar ten-

don was perpendicular to the tibial plateau (10).

The triple tibial osteotomy (TTO) combines three osteoto-

mies made in the proximal tibia to create a partial tibial

wedge osteotomy caudal to a partial tibial crest osteotomy.

This procedure partially levels the tibial plateau while advan-

cing the tibial tuberosity and patella tendon in an attempt to

neutralize femorotibial shearing forces across the stifle (5).

Proposed advantages of TTO over other proximal tibial

osteotomies include the need for less radical angular changes

of the tibia than would be indicated in procedure’s that solely

level the tibial plateau or advance the tibia tuberosity, mini-

mal change to the femorotibial articulating surfaces, minimal

need for specialized implants or surgical equipment and no

loss of tibial length (5,13).

There is no information in the work on the surgical find-

ings, complications and outcome associated with the TTO in

small breed dogs. The purposes of this study are to docu-

ment the surgical findings and complications of TTO for the

treatment of cranial cruciate ligament disruption in small

breed dogs.

Materials and Methods

This study was conducted under approval of ethical com-

mittee of Gyeong-sang national university laboratory animal

center (Approval number: GNU-150402-D0016). The twelve

dogs weighed less than 10 kg, and had a normal ambulation

on physical examination. The medical data was noted for

breed, age, sex, weight, affected limb and meniscal tear.

1Corresponding author.E-mail : jh1000@gnu.ac.kr

8 Tae-Hwan Kim et al.

Twelve dogs had unilateral TTO procedures. The mean body-

weight of dogs was 6.25 kg (range 4.6 kg to 8.6 kg). The

mean age of the dogs was 3.4 years (range 2 years to 7

years). There were seven entire females, five entire males.

The dogs had been fasted for about 12 hours before the

operation. They were premedicated with medetomidine (0.2

mg/kg, administered subcutaneously (SC), Domitor®; Pfizer,

NY, USA) together with acepromazine (0.05 mg/kg, SC,

Sedaject®; Samu Median, Seoul, Korea) and atropine (0.04

mg/kg, SC, Atropine®, Jeil Pham., Daegu, Korea). Cefazolin

(25 mg/kg, SC, Hankook Korus Pharm Co, Seoul, Korea)

was used as a prophylactic antibiotic. After placement of a

catheter in the cephalic vein, general anesthesia was induced

with etomidate (2 mg/kg, administered intravenously (IV),

Etomidate-®Lipuro; B. Braun Melsungen AG, Germany)

titrated to effect and administered to effect preceding tra-

cheal intubation. Anesthesia was maintained with isoflurane

(TerrellTM, Piramal Critical Care, USA) in 100 percent oxy-

gen via endotracheal intubation in a circle rebreathing sys-

tem. Normal saline was administered at 10 mL/kg/hour through

the cephalic vein during the whole procedure. The dog’s

heart rate, body temperature, percutaneous blood oxygen sat-

uration (SpO2) and end tidal CO2 (Et CO2) was monitored

during anesthesia. A circulating water blanket (Medi-Therm®,

Gaymar, NY, USA) with 38~39oC was used to maintain body

temperature.

CCLR modeling preceded the TTO procedure. On the pre-

operative radiograph, the TPA was defined according to the

conventional method (3,20). The patellar tendon, the patellar

tendon angle (PTA) and the correction angle (CA) were

defined as previously described (5,8,23). Pre-operative radio-

graphic calculations were as follows (Fig 1). Tibial plateau

(TP) was defined by estimating the position of the surface of

the medial tibial condyle, which was slightly convex in

shape. The location of the tibial plateau was determined by

identifying the cranial and caudal points and drawing a line

between them. The cranial most point of the medial tibial

condyle was visible as a small discrete step. The caudal point

was the point of insertion of the caudal cruciate ligament-the

apex of popliteal notch was a useful point of reference. A

line marking the cranial edge of the straight patellar liga-

ment (PL) was drawn. Position a straight-edge cranial to the

stifle and slide it caudally until it first touches points on the

patella and tibial crest. The distance between theses points

was the PL length. The tibial crest osteotomy (TCO) was

drawn with exactly the length of PL. The TCO was made

parallel to the axis of the tibial shaft and was usually parallel

to the cranial aspect of the tibial crest. A line was created by

drawing a line perpendicular to TP starting from the proxi-

mal end of PL. the correction angle (CA) was angle between

PL and the line. The angle of the tibial wedge osteotomy was

calculated according to the currently recommended formula;

wedge angle (WA) = 0.6 X CA + 7.3o (22). The central axis

of the wedge was located exactly halfway along the TCO. It

was drawn in the central axis of the wedge as a line extend-

ing caudally and perpendicularly from the TCO line at its

mid-point.

Surgery was performed as described by Bruce et al (5)

with the minor modifications that no meniscal release proce-

dures were performed (Fig 2). The dog was positioned in lat-

eral recumbency with the affected leg down and parallel to

the operating table, which was to explore the medial aspect

of the stifle joint. Carprofen (2.2 mg/kg, PO, twice daily,

Carprofen®, Zoetis, USA), cefadroxil (25 mg/kg, PO, bid,

Cefaxil®; Koruspharm, Jecheon, Korea) and famotidine (0.5

mg/kg, PO, bid, Famotidine®; NELSON, Korea) were given

for 7 days.

Radiographs were taken immediately following surgery, 2,

4 and 8 weeks postoperatively. On the postoperative radio-

graphs, the TPA and patellar tendon angle (PTA) were mea-

sured (3,20). The intended wedge angle was substracted from

the preoperative TPA to give the anticipated postoperative

TPA. The difference between the anticipated and the achieved

postoperative TPA was calculated. On radiographic examina-

tion following surgery, major complications were defined as

those that required further surgery or treatment. Other com-

plications were considered to be minor.

Visual lameness of the dogs was evaluated at stance, walk

and trot in preoperative TTO surgery, 4 weeks and 8 weeks.

Visual lameness was graded using a modified scoring sys-

tem (12): 0 = no detectable lameness (clinically sound); 2 =

barely detectable lameness; 4 = mild lameness; 6 = moderate

lameness; 8 = severe lameness (carries limb when trotting);

10 = non-weight bearing (could not be more lame).

The visual lameness score was measured in preoperative

TTO surgery, 4 weeks and 8 weeks. Statistical analysis was

Fig 1. Preoperative surgical plan for the TTO surgery. CA is the

correction angle formed between the patellar tendon and a line

originating at the cranial-most aspect of the patella and perpen-

dicular to the tibial plateau. PTA is the angle created by the

intersection of the tibial plateau extraspolation line and the

patella tendon. TPA is tibial plateau angle. PT is patellar tendon.

TWO is tibial wedge osteotomy. TCO is tibial crest osteotomy.

The dotted line bisects and is perpendeicular to the TCO.

Triple Tibial Osteotomy (TTO) for Treatment of Cranial Cruciate Ligament Rupture in Small Breed Dogs 9

performed using SPSS 21.0 (SPSS Inc, Chicago, Ill, USA).

A repeated measure ANOVA (RM-ANOVA) was used to

investigate the change from preoperative lameness. P-value

less than 0.05 was considered to be statistically significant.

The results expressed with a means ± standard deviation (S.D).

Results

The TTO surgery was performed on 4 left- stifle joints and

8 right-stifle joint. The duration of lameness before TTO sur-

gery was 1 ± 0.5 weeks. All dogs had no gross pathological

changes observed in the medial meniscus on arthrotomy.

On the preoperative and the immediate postoperative ra-

diographs, The TPA, PTA, and others were measured (Table

1). The mean preoperative stifle joint extension angle was

130.1 ± 3.7o. The mean preoperative PTA was 103.8 ± 4.8o and

the mean preoperative TPA was 25.7 ± 7.1o. The mean in-

tended WA was 16.6 ± 1.7o.

On postoperative radiographs, the postoperative TPA was

different from the anticipated TPA by 9.1 ± 6.6o. The mean

postoperative PTA was 92.1 ± 2.1o and the mean postopera-

tive TPA was 11.0 ± 5.4o.

In ten TTO procedures (83%), incomplete osteotomy of

the tibial crest had been achieved with an intact segment of

the cranial tibial cortex preserved at the distal end of tibia

crest following tuberosity advancement. The ten closed

wedge osteotomies were stabilized with 2.0 mm tibial pla-

teau leveling osteotomy (TPLO) plate (Veterinary Instrumen-

tation, Henry schein®, Shefield, UK). In two dogs, the closed

wedge osteotomies were stabilized with 2.4 mm TPLO plate

Fig 2. TTO procedure; Three linear (TCO line and WA line) osteotomy. A. The TCO was completed with an oscillating saw (the TCO

proximal end should terminate within the non-articular part of the proximal tibia, caudal to the patellar ligament insertion and cranial

to the cranial edge of the meniscus). B. A saw blade was used to cut a full thickness wedge from the proximal tibia and was orientated

slightly caudally to cut the caudal and caudo-lateral parts of the lateral tibia. C. The tibia wedge was closed. The plate was then fixed

to the bone using cortical screws.

Table 1. Radiographic measurements (degree)

Pre EA Pre PTA Pre TPA CA WA (mm) WA PO PTA PO TPAAnt PO

PTA

PO TPA

-Ant PO TPA

1 130.3 105.0 41.0 16.2 3.0 17.0 90.7 14.9 24.0 −9.1

2 126 98.3 30.8 12.6 6.0 14.9 89.5 17.7 15.9 1.8

3 132.7 104.0 23.5 16.8 2.0 17.4 96.5 6.0 6.1 −0.1

4 134.9 103.0 27.0 15.2 4.0 16.4 92.6 11.6 10.6 1.0

5 137.4 105.5 21.0 16.2 4.0 17.0 93.3 7.9 4.0 3.9

6 132.0 98.5 13.4 12.6 2.6 14.9 91.6 6.0 −1.5 7.5

7 125.0 108.7 28.0 18.6 5.0 18.5 89.7 16.8 9.5 7.3

8 127.0 99.0 27.0 12.1 3.0 14.6 90.4 19.5 12.4 7.1

9 129.0 114.5 31.0 21.6 2.6 20.3 95.4 12.8 10.7 2.1

10 128.0 99.6 18.0 12.4 8.0 14.7 91.0 2.0 3.3 −1.3

11 131.0 107.0 26.0 17.0 2.0 17.5 92.0 9.0 8.5 0.5

12 128.3 103.0 22.0 15.1 3.0 16.4 92.0 8.0 5.6 2.4

Mean ± SD 130.1 ± 3.7 103.8 ± 4.8 25.7 ± 7.1 15.5 ± 2.9 3.8 ± 1.8 16.6 ± 1.7 92.1 ± 2.1 11.0 ± 5.4 9.1 ± 6.6 1.9 ± 4.6

Pre; Preoperative, PO; postoperative, EA; Angle of stifle joint, Ant; Anticipated, TPA; Tibial Plateau Angle, CA; Correction Angle, WA;Wedge Angle PTA; Patellar Tendon Angle

10 Tae-Hwan Kim et al.

(Veterinary Instrumentation, Henry schein®, Shefield, UK).

Supplementary implants were applied in the two procedures

with fracturing of the tibial crest osteotomy at the distal end

of tibia crest. These additional implants were a cerclage wire.

Four different complications were detected intra-operatively

(Fig 3). Meaningfully, in all dogs, the caudal cortex of the

tibia fractured during the TTO procedure (Fig 3A). In two

dogs, fracture through the distal end of the tibial crest osteot-

omy occurred during the procedure, requiring a cerclage wire

(Fig 3 B). Proximal fibular fracture was occurred in only one

dog (Fig 3 C). In two dogs, tibial lateral cortex defect was

occurred (Fig 3 D).

We define a major complication as an undesirable develop-

ment that required further diagnostic investigation or surgi-

cal treatment. Follow-up examinations were performed for 8

weeks after TTO procedure. Post-operative major complica-

tion did not occurred in 8 weeks. Minor complications

including bruising and swelling occurred in five dogs (41%).

The dogs were healed in 2 weeks uneventfully.

Four weeks postoperative radiographs demonstrated evi-

dence of progressive bone union at the osteotomy site and

fractured sites in all dogs. Eight weeks postoperative radio-

graphs demonstrated radiographic union in 10 dogs (83%). In

consequence, all dogs healed in 11 weeks (100%).

The visual lameness score varied from 6 to 9 before TTO

surgery. Ten dogs (83%) revealed weak lameness (grade 2 of

10) in 4 weeks and normal ambulation in 8 weeks postoper-

atively except for only one dog returned in 11 weeks.

Discussion

TTO surgery is used to change the biomechanics of the sti-

fle to overcome CTT in dogs with CCLR. The TTO is prox-

imal tibial osteotomy procedure incorporating features of the

TPLO procedure and TTA procedures. The purpose of the

TTO procedure is to reduce the PTA to 90o. The mean post-

operative PTA achieved of 92.1o, compares favorably with

94.1o achieved by Bruce et al (5), with the 93.5o achieved by

Renwick et al (22) and also with the 95.5o achieved using the

TTA technique (10). Although the postoperative mean PTA is

almost 90o, the TTO technique failed to achieve the aim of

the PTA 90o. Thus, dynamic stability of the stifle cannot be

assured. The mean wedge angle removed during the surgical

procedures was 16.6o. This angle was slightly larger than the

mean wedge angle previously reported by Bruce et al (5) of

11.5o, by Renwick et al (22) of 15.9o and by Moles and oth-

ers (16) of 13.6o. The most likely examination for the differ-

ences is resulted from variations in stifle joint flexion angles

on preoperative wedge angle formula (16). The radiographic

protocol for TTO demands the stifle to be positioned medio-

laterally at flexion angle of 135o in order to determine the

amount of tibial tuberosity advancement involved to ensure

PTA 90o (5). This positioning is difficult to be achieved accu-

rately. The difficulty provides a potential cause of error in

determining the exact wedge osteotomy angles demanded

preoperatively and postoperative assessment of the tibial pla-

teau to patella tendon angles achieved (11). This source of

inaccuracy is similar for the TTA procedure and is compara-

ble to the previously reported inter-observer variability in

measuring tibial plateau slopes of up to 6o (6).

Bruce et al concluded that measurement of the TPA is not

needed when performing the TTO (18). However, Renwick

and others suggested that measurement of the TPA is neces-

sary to avoid over-correction of the TPA and also to identify

cases that may not be ideal candidates for the technique (9).

In this study, the preoperative mean TPA was 25.7 ± 7.1o and

the postoperative mean TPA was 11.0 ± 5.4o. A subgroup of

dogs was identified with below average TPAs and relative

large CAs. In this subgroup (dog no.5, 6 and 10), advancing

the tibial tuberosity to the recommended position using the

TTO procedure may have resulted in a less than 5o TPA. In

vitro studies of the TPLO where the TPA is reduced have

shown loading of the caudal cruciate ligament when the TPA

is 6o or less (21,29). And an in vitro study of TTA where the

TPA was unchanged showed caudal tibial translation when

the PTA was less than 90o (1). Because there are no in vitro

studies to assess the effect of combined TTA and TPA reduc-

tion, it is logical idea that when using the TTO, if the TPA is

reduced to less than 5o, the effect of increased loading of cau-

dal cruciate ligament is likely to be at least equal to if not

greater than the loading created at the same angle in perform-

ing a TPLO (22). Thus in these three dogs (dog no. 5, 6, 10),

we reduced the TPA to 5o, as recommended for the TPLO

method (1).

The combined osteometer and saw guide is too big to

Fig 3. Intra-operative complications. A. In all dogs, the caudal

cortex of the tibia fractured during the TTO procedure. B. In two

dogs (No. 2 and 3 dogs), fracture through the distal end of the

tibial crest osteotomy occurred during the procedure, requiring a

cerclage wire. C. Proximal fibular fracture was occurred in only

one dog (No. 6 dog). D. In two dogs (No. 1 and 11 dogs), tibial

lateral cortex defect was occurred.

Triple Tibial Osteotomy (TTO) for Treatment of Cranial Cruciate Ligament Rupture in Small Breed Dogs 11

apply on small breed dogs. So the wedge osteotomy angle was

converted into length. The difference between the antici-

pated and the achieved postoperative TPA was 1.9 ± 4.6o,

which was the similar result achieved by Renwick et al (9).

Fracture through the caudal tibial cortex occurred in all

dogs. The tibial wedge osteotomy should be gradually closed

by applying upward pressure on the foot. The resultant action

served to gradually close the gap between wedge osteoto-

mies but at the same time keeping the caudal tibial cortex

intact (18). It has been hypothesized that the caudal tibial

fracture occurred because the tibial wedge osteotomy was

rapidly closed. Different types of tibial tuberosity fractures or

avulsions have previously been reported with TPLO, TTA

and TTO (4,5,22). Only 17% of stifles (dog no.1 and 3) in

our study, fracture of tibial crest from the distal flexion point

appeared. The two dogs had larger CA than the average angle.

Age related brittleness of the bone and increased advance-

ment of the tibial tuberosity associated with large closing-

wedge osteotomies may account for this tibia fracture (15). It

is recommended that the use of additional implants in the tib-

ial crest segment during TTO only if intraoperative fracture

occurs at the tibial crest flexion hole (28). Moles et al recom-

mend stabilization using K-wire and a tension band wire

(22). In our study, cerclage wire was placed to stabilize the

fractured bone, maintained for 8 weeks postoperatively. Fib-

ular fracture has been recorded as a complication with other

tibial plateau levelling technique (7,19,27). This complica-

tion was not regarded clinically significant in our study and it

was left without treatment. In addition, it would be consider

delayed bone healing of osteotomy sites as a potential com-

plication. It also needed careful applications of angle of the

osteotomies, because of the individual variation of shape and

small size of the tibia in small breed dogs.

The visual lameness score ranged from grade 6 to 9 before

TTO procedure. Ten dogs (83%) had a grade 2 of 10 in 4

weeks. And normal ambulation in 8 weeks postoperatively

except for only one dog which was returned in 11 weeks. In

other studies, lameness score was 2.4 of 5 at 6 weeks postop-

eratively and still was same score (2.1 of 5) at 7-10months

after ECR (14). And dogs had a 2 of 5 lameness score at 8

weeks after TPLO (2). Our result showed faster recovery

than other procedures on visual lameness score.

There are limitations in this study. Significant point is the

lack of any in vitro or kinetic studies on the TTO. For exam-

ple, it is unidentified how a less than 0o TPA affects stifle

joint shear force when the PTA is 90o. Or does a change in

PTA of only 2o induce a stable stifle if the pre-operative PTA

is 92o. Further retrospective or prospective studies are required

to document long-term complications and clinical outcomes

for TTO.

TTO surgery, like TPLO and TTA, is used to change the

biomechanics of the stifle to overcome cranial tibial thrust in

dogs suffering from cranial cruciate ligament disruption. Our

outcomes for TTO procedure in small breed dogs are similar

to those previously reported for large breed dogs. Despite

frequent minor complication, it appears that the TTO is an

alternative procedure for management of CCLR in small

breed dogs.

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