Replacement of the Anterior Cruciate Ligament in the Dog

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3. small anim. Pract. Vol. 7 , 1966, pp. 351 to 359. Pergamon Press Ltd. Printed in Great Britain.

Replacement of the Anterior Cruciate Ligament in the Dog

ANDERS STRANDE Surgeery Department, Veterinary ColleEe of Norway, Oslo

Abstract-A method using the central one third of the patellar ligament, a full-length strip of the superficial one-half of the patella and a full thickness strip of the quadriceps tendon was used as a replacement for the anterior cruciate ligament in nine experimental dogs and four clinical cases. The pathology and histological picture of the stifle joints in the experimental dogs are described. The results are encouraging.

I N T R O D U C T I O N IN 1963, Jones described a new surgical technique for the reconstruction of a ruptured anterior cruciate ligament in man. Since this appeared interesting the author decided to investigate his technique.

Jones entered the knee joint through a medial parapatellar incision from 1 in. proximal to the patella to just distal to the tibial tubercle. With the knee flexed at 90” he drilled a tunnel, with a $‘g in. drill bit, from the anterior margin of the intercondylar notch, which is just visible, in a proximal and lateral direction through the lower end of the femur to emerge just proximal to the lateral femoral condyl. At the point where the drill bit emerges, a second incision is made. The canal in the femur is made semi-triangular with a curette.

“Two parallel longitudinal incisions, +j in. apart, are then made from anterior to posterior through the entire thickness of the patellar ligament (Fig. l ) , thereby isolating its central third. These parallel incisions are continued proximally across the central portion of the patella and on up into the quadriceps tendon for a distance of 1 in. beyond the superior margin of the patella. The Stryker saw is then used to remove a block of bone, triangular in cross section, from the superficial one-half of the patella. This block extends from the superior to the inferior pole of the patella. Removal is accomplished by making converging saw cuts which meet in the depth of the bone. The articular surface of the patella is not encroached upon. In this manner a new ligament, still attached below to the tibial tubercle, is constructed. I t consists, from proximal to distal of a full-thickness strip of the quadriceps tendon, 1 in. long; a full-length strip of patella which is triangular in cross section and composed of the superficial one-half of the patella and overlying periosteum and fascia; and full

Next, as Jones says:

35 1

352 A N D E R S S T R A N D E

thickness of the central one third of the patellar ligament. This new ligament is turned downwards and two heavy chromic sutures are placed through its proximal end, the portion derived from the quadriceps tendon.

Through the surgical defect in the central portion of the patellar ligament (Fig. 2) the fat pad is undermined from front to back. With the knee held in 90" of flexion, the new anterior cruciate ligament is reflected into the joint beneath the fat

tunnel in femur

-------L-- piece of quadriceps tendon

collateral lateral lig. central 1/3 of patellar lig.

FIG. 2. A+B+ C . New anterior cruciate ligament. A. 9 of patellar ligament. B. Piece of patella. C . Section of quadriceps tendon. D. Tuberositas tibia. E. Patella;

pad. With the assistance of a guide wire, the chromic sutures are drawn through the canal in the femor prepared earlier. These sutures emerge through the second incision in the lateral aspect of the thigh. They are used to draw the bone portion of the ligament up into the canal in the femur. The ligament is pulled taut after the knee has been brought to 10" of flexion. As a rule, with the drill hole placed in the

FIG. 1. A. Section of quadriceps tendon. B. Piece of patella. C. + of patellar ligament. New ligament A+B+C.

To make a better contrast in the illustration the place where the section of patellar ligament and quadriceps tendon are removcd is covcrcd with carbon paper.

FIG. 3. Dog No. 9. 9 R right stifle joint. A. New anterior cruciate ligament. B. Anterior cruciate ligament in left normal stifle joint.

( f a c i n g p . 352)

R E P L A C E M E N T O F T H E A N T E R I O R C R U C I A T E L I G A M E N T 353

intercondylar notch just posterior to the margin of the articular cartilage on the lower end of the femur, the ligament can be drawn into the canal to a depth where only the distal end of the patellar fragment projects into the intercondylar notch. The remainder of the patellar fragment is then deep in the canal created in the femur. If the lower end of the patellar fragment is too prominent in the intercondylar notch, it can be readily rongeured away without weakening the artificial cruciate ligament. The chromic sutures which have been brought out through the hole in the lateral aspect of the femur are then used to secure the tendon to the lateral aspect of the femur by passing them through the periosteum. Fixation to the bone has not been necessary since the bone block is wedged so tightly in the femur that the sutures are probably unnecessary. Absence of the pre-existing drawer sign can then be demon- strated. The surgical defect in the quadriceps tendon and in the patellar ligament are closed from side to side with interrupted sutures.”

MATERIAL A N D M E T H O D In nine experimental dogs varying in age from 6 months to 8 years old and

weighing from 10 to 35 kg, 0 - 5 cm of the anterior cruciate ligament was removed. The technique which Jones used in the drilling of the tunnel in the femur was changed: instead of starting the drilling in the intercondylar notch it was started at the lateral condyle of femur a little above the insertion of the lateral femorotibial ligament using a 4 or 5 mm drill tub.

The tunnel emerged at the insertion of the anterior cruciate ligament on the medial side of the lateral condyle. This technique is the most frequently used in canine stifle surgery. The piece of the quadriceps tendon was taken so that it was long enough to be sutured to the lateral femoro-tibia1 ligament with stainless steel wire No. 00 after passing through the tunnel. A dental drill with a saw of 3 cm diameter and 0 . 5 mm thickness was used to saw the cut in the patella. A solution containing penicillin and streptomycin was deposited into the joint, the dog remained on these antibiotics for 5 days. The limb was supported in a Thomas splint for 14 days with slight flexion of the stifle joint. After surgery both stifle joints were X-rayed in the anterio-posterior plane and in the lateral medial plane. I n the last position the stifle joint was slightly flexed, and an attempt was made to produce the anterio- posterior drawer movement.

The dogs were checked monthly for the state of lameness and the anterio- posterior drawer movement. The degree of lameness was classified in categories from 9 to 4 degrees. With 3 degree, the lameness was only visible to a specialist. With 1 degree, the lameness was just visible to a layman. With 4 degrees the dog did not put any weight on the affected limb. The stifle joints were also X-rayed every third month in the positions mentioned above. Three of the dogs were killed after 3 months. three after 6 months and three after 9 months. Both stifle joints were examined and photographed in colour and black and white. Sections were taken from the bony tunnel containing the piece of patella, and from the new anterior cruciate ligament where it was free in the joint cavity. In the non-operated stifle joint sections were taken of the normal anterior cruciate ligament and the patellar ligament. They were


fixed in formalin. The bony sections were decalcified with Decal*, and then embedded in paraffin, cut in slices of 10 p thickness, and stained with haematoxylin- eosin and van Gieson stain for collagen fibres.

RESULTS 3 months after surgery

Dog 3. Bedlington Terrier, male, l-yr-old, weight 11 kg. After 2 months the dog walked freely and showed a lameness of 1 degree. No antero-posterior drawer movement, but a partial medial luxation of the patella was observed. After 3 months the lameness was reduced to 4 degree.

Pathological examination. The stifle joint was slightly enlarged with some thickening of the joint capsule. A few excrescences at the inner border of the medial femoral condyle were seen. The cartilage on the ridge of the medial condyle was slightly worn down by the subluxated patella. The new anterior cruciate ligament was strong and taut. I t was partly adherent to the anterior part of the posterior cruciate ligament. Both the menisci were normal as was the rest of the joint cartilage. Nothing abnormal was observed in the other stifle joint.

Dog 8. Poodle, male, 5-yr-oldY weight 10 kg. After 2 months the dog showed 1 + degrees of lameness with no antero-posterior drawer movement. After 3 months the dog ran and jumped showing no sign of lameness, but there was still some atrophy of the muscles in the affected limb.

Pathological examination. The stifle joint was slightly enlarged. No increased synovial fluid and no excrescences were observed. The new anterior cruciate ligament was strong and taut. The defect in the patellar ligament and the groove in the patella were healed. Nothing abnormal was observed in the other stifle joint.

Dog 9. English Setter, male, 6-yr-oldY weight 24 kg. After 2 months the dog showed 13 degrees of lameness with a slight antero-posterior drawer movement. After 3 months the lameness was reduced to + degree.

Pathological examination. The stifle joint was enlarged with increased synovial fluid. A few excrescences were seen at the outer borders of the femoral condyles. The new anterior cruciate ligament was strong and taut (Fig. 3). An area of necrosis 5 x 6 mm had formed in the cartilage of the lateral condyle of the femor. The corresponding cartilage in the tibia was worn down. Both the menisci were normal. The non-operated stifle joint was normal, except that a similar necrosis to that seen in the other stifle joint was found in the cartilage of the medial condyle of the femur.

The histological picture was similar in these three dogs and will be described together. A cross section of the tunnel in the femur with the piece of the patella showed the following features: in the central part of the tunnel a few osseous bars with pyknotic cells were observed. All round the tunnel there was rich vascularized

*“Decal”: Omega Chemical Co., Garden City Park, New York.


connective tissue forming new osseous bars along the border of the tunnel. Almost the whole piece of the patella had been absorbed and rebuilt.

The free new anterior cruciate ligament: near the tibial attachment the ligament looked like the normal patellar ligament, although some small necrotic areas partly replaced by connective tissue were observed. Near the attachment of the ligament to the piece of the patella in the femoral tunnel very little of the normal structure of the patellar ligament could be seen. Necrotic areas replaced by newly formed connective tissue, which in some placed had started to form bundles, predominated in the picture.

6 month after surgery Bog 2. Elkhound, male, 3-yr-old, weight 18 kg. After 2 months the dog showed

a lameness of 1 degree with some antero-posterior drawer movement. After 4 months the dog showed no sign oflameness . After 6 months there was still some atrophy of the muscles in the affected limb.

Pathological examination. The joint and joint capsule were thickened and the synovial fluid slightly increased. There were a few excrescences on the condyles of the femur. The new anterior cruciate ligament was thin and not very strong. The posterior cruciate ligament was increased in thickness due to granulation tissue. The menisci were normal and so was the other stifle joint.

Dog 6. German Shepherd, female, 8-yr-old, weight 34 kg. Two months after surgery the dog showed a lameness of 1 & degrees with some antero-posterior drawer movement. After 3 months the lameness was reduced to & degree and the same degree of lameness was seen after 6 months, although the antero-posterior drawer movement could not then be produced. Muscle atrophy in the limb was not strongly marked.

Pathological examination. The joint was enlarged, specially at the tibial attachment of the medial ligament. The synovial fluid and the joint capsule were increased. A few excrescences were found at the femoral condyles. The new anterior cruciate ligament was solid and taut. The medial meniscus was torn at its concave border. The corresponding cartilage in the tibia was slightly worn down.

Dog 1. German Shepherd, female, 6-yr-old, weight 32 kg. After 2 months the dog showed a lameness of 1 & degrees and distinct antero/posterior drawer movement. After 3 months the lameness was reduced to 1 degree and a little less antero-posterior drawer movement could be produced. After 6 months the dog ran and jumped freely, but showed a lameness of & degree when under strain. Some antero-posterior drawer movement was still present.

Pathological examination. There was distinct atrophy of muscles in affected limb, and also enlargement of the stifle joint, especially on the medial side. There was increased synovial fluid and marked thickening of joint capsule and the surrounding tissue. The new anterior cruciate ligament was ruptured at its attachment to the femoral condyle. The remainder of the ligament was adherent to the joint capsule.


There were many excrescences along the borders of the femoral condyles and the spine of tibia. The medial meniscus was torn at its concave border and it was ruptured in two places. The tibial cartilage corresponding to this position showed some erosions. The other stifle joint was normal.

The histological picture in these three dogs was similar so they are described together. The bony tunnel in the femur was reduced to half its original size by newly formed bone. No remains of the transplanted piece of patella were seen. Instead of bone the centre of the tunnel was filled with richly vascularized connective tissue. The free ligament in Dog 2 consisted of connective tissue and granulomatous tissue. No remains of the patellar ligament were observed. In Dog 6, scattered areas with almost normal structure of the patellar ligament mixed with necrotic foci and abundant newly formed connective tissue sometimes arranged in bundles were seen. In dog 10 the most of the remains of the patellar ligament which was adherent to the joint capsule looked like the original patellar ligament.

9 months after surgery Dog 4. Collie mixed breed, female, 9-months-oldY weight 14 kg. After 2 months

the dog showed a lameness of 14 degreeswithsomeantero-posterior drawer movement. After 4 months the lameness was reduced to 4 degree. After 9 months the dog only showed a little lameness when under strain. There was still distinct antero-posterior drawer movement and atrophy of the muscles of the limb.

Pathological examination. Synovial fluid was increased, the joint capsule thickened and discoloured a brownish colour. Many excrescences along the borders of the femoral condyles, and also some erosions in the cartilage both in the patellar grove on the femur and the medial condyle of the tibia were observed. The new anterior cruciate ligament was ruptured at the attachment to the femoral condyle. The rest of the ligament was adherent to the tibial spine. The medial meniscus was torn at its concave border. The other stifle joint was normal.

Dog 5. Spitz, female, l-yr-old, weight 12 kg. Two months after surgery the dog showed a lameness of 2 degrees with slight antero-posterior drawer movement. After 4 months there was 1 degree lameness, and after 6 months no lameness and no antero-posterior drawer movement. There was still some atrophy of muscles in the affected limb after 9 months. A slight subluxation of the patella to the medial side was observed.

Pathological examination. The newly formed anterior cruciate ligament was solid and taut with a diameter of from 4 to 6 mm. The other joint tissue and the other stifle joint seemed to be normal.

Dog 7. Spitz, female, 9 months old, weight 12 kg. After 2 months the dog showed a lameness of 1 degree and no antero-posterior drawer movement. After 3 months no lameness was observed, but there was still marked atrophy of the muscles in the limb. It was not until after 9 months that the muscle atrophy had almost disappeared.


Pathological examination. The newly formed anterior cruciate ligament was solid and taut. Nothing abnormal was seen in the other joint tissue or in the other stifle joint.

Histological picture in these three dogs. The tunnel in the femur had almost been reconstructed by newly formed osseous tissue, and the remaining tunnel was filled with connective tissue. The new anterior cruciate ligament in Dog 5 looked almost like a normal patellar ligament, while in Dog 7 it consisted of bundles of connective tissue arranged more like a normal anterior cruciate ligament.

In July 1964, four clinical cases with rupture of the anterior cruciate ligament were operated using the same technique.

31 1/64 Poodle, female, 5-yr-oldY weight 9 kg. The dog suddenly became lame in the left hind limb after playing 5 days before. Surgery revealed a total rupture in the middle of the anterior cruciate ligament. Three months after surgery the dog showed a lameness of 1 degree with no antero-posterior drawer movement. Six months after surgery the dog was free from lameness even after walking for several hours. Unfortunately the dog developed diabetes mellitus and was put to sleep recently without the author’s knowledge.

315/64 Airedale Terrier, male, 3-yr-oldY weight 22 kg. The dog suddenly became lame, and stopped putting any weight on left hind limb 2 days before when he was out playing. Surgery revealed a total rupture of the attachment to the femur of the anterior cruciate ligament. Some chondroid-like pearls were seen together with fresh bloodclots on the remaining brush-like ends of the ligament. Together with some excrescences along the femoral condyles this indicated that there had been an earlier partial rupture of the ligament. Three months after surgery the dog showed a lameness of 1Q degrees with a slight antero-posterior drawer movement. Six months after surgery the dog was almost free from lameness. One year after surgery the dog jumped and ran freely. The left stifle joint was thicker than the right one. No antero-posterior drawer movement could be produced.

325164 Stover, female, 5-yr-oldY weight 22 kg. The dog suddenly became lame and stopped putting any weight on the limb after running in the forest the day before. Surgery revealed a total rupture of the anterior cruciate ligament at its attachment to the tibia. Three months after surgery the dog showed a lameness of 13 degrees with very little antero-posterior drawer movement. Six months after surgery the dog showed a slight lameness after being under strain. One year after surgery no lameness could be observed although the affected stifle joint was somewhat thicker than normal and there was still some atrophy of the muscles. The owner had used the dog quite a lot in hare hunting during the winter, and had no complaints regarding the dogs’ mobility.

337164 German Shepherd, male, 3&yr-old, weight 32 kg. The dog suddenly became lame in the right hind limb after exercise 1 week previously. Surgery revealed a total rupture through the middle of the anterior cruciate ligament. Six months after surgery the dog was almost free from lamneess. At this time the dog became lame


in the left hind limb. The lameness lasted a couple of weeks, and was probably due to a partial rupture of the anterior cruciate ligament in the left stifle joint.

The last 4 months the owner had used the dog extensively and he had no complaint regarding the dog’s mobility. Examination 1 yr after surgery showed that the dog’s mobility seemed to be normal. The muscles in the hind limbs were well grown. Both the stifle joints were enlarged. No antero-posterior drawer movement could be produced. X-ray of both stifle joints showed a marked arthritis.

DISCUSSION In the nine experimental dogs the new anterior cruciate ligament had ruptured

in two of them. The rupture occurred at the same place, i.e. at the junction between the patellar ligament and the piece of the patella. This seems to be the weakest point in the transplanted ligament. This was also apparent at operation, and furthermore this region gets the poorest nourishment. Except for the terminal portion nearest the tuberosity of tibia the transplanted ligament degenerates and is eventually rebuilt forming a new ligament. The terminal portion almost retains its normal construction, probably because it keeps most of its normal blood supply. The further from this attachment to the tuberosity of tibia, the poorer the blood supply will be. Most of the ligament which lies free in the joint cavity will therefore not obtain the necessary blood supply and has to be revascularized. The piece of patella in the bone tunnel degenerates and will be replaced by normal osseous tissue. After 6 months, half of the tunnel is reconstructed and after 9 months there is only a spur left on the tunnel.

Most of the dogs were almost free from lameness after 3 months despite of the fact that some of them had got a little arthritis. In the two dogs, No. 10 and No. 4, where the transplanted ligament had ruptured, it is interesting to note that No. 10 only showed slight lameness when euthanasied after 6 months and No. 4 was almost free from lameness when euthanasied after 9 months. Both of them had developed severe arthritis.

The results obtained both in the experimental dogs and the clinical cases are encouraging; it is suggested that this method will become one of the best choices when replacing a ruptured anterior cruciate ligament.

REFERENCE JONES, K. G. (1963) J . Bone Jt Surg. 45A, 925-932.

Sammendrag-Det beskrives en ny metode ti1 B erstatte et overrevet ligamentum cruciatum anterius i kneleddet hos hund. En bruker den midterste tredjedelen av ligamentum-patella i hele dets tykkelse, et tilsvarende bredt stykke av ytterste halvpart av patella og et tilsvarende bredt stykke av senen ti1 musculus quadriceps femoris fra dew tilheftning proksimalt pB patella. Operasjonsmetoden er brukt pa ni forsokshunder og fire kliniske tilfelle av ligamentruptur. Pa forsokshundene ble kneleddene undersokt makro og mikroskopisk etter avlivningen. Resultatet etter operasjonene var oppmuntrende.

R6sumLUne mtthode comportant l’utilisation du centre tiers du ligament rotulien, toute une longueur de la moitit superficielle de la rotule ainsi que toute une tpaisseur du tendon quadriceps a t t t appliqute pour remplacer le ligament cruciforme anttrieur chez neuf chiens d’exptrience et


quatre cas cliniques. La pathologie et l’image histologique des grassets chez les chiens d’exptrience furent dtcrites, et les rtsultats en furent encourageants.

Zusammenfassung-Eine Methode, die das zentrale Drittel des Ligamentum patellae, einen Streifen in voller Lange der oberflachlichen Halfte der Patella und einen Streifen der ganzen Dicke der Sehne des Quadriceps benutzt, wurde als Ersatz fur das Ligamentum cruciatum in 9 Experiment Hunden und 4 klinischen Fallen angewandt. Die Pathologie und Histologie der Kniegelenke der Experiment Hunde wurden beschrieben. Die Resultate waren ermutigend.

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Replacement of the Anterior Cruciate Ligament in the Dog