Resection arthroplasty of the hip joint in dogs and cats

Results of clinical examination, radiography and motion analysis. Department of Surgery, Faculty of Veterinary Medicine, Ludwig Maximilian University, Munich, Germany.

Authors: W. Off; U. Matis. Department of Surgery and Small Animal Reproduction, Ludwig Maximilian University, Munich, Germany.

VetCompOrthopTraumatol 2010; 23: 297-305

This article was originally published in 1997 in the magazine TierärztlichePraxis. Both authors approved its publication in English and also provided a translation.

Original source: Off W, Matis U. ResektionsarthroplastikdesHüftgelenkesbeiHundenundKatzen.

Klinische, röntgenologische und ganganalytische Erhebungen an der Chirurgischen Tierklinik der Ludwig-Maximilians-Universität München. Tierärztl Prax 1997; 25: 379–387.

Summary

From 1978 to 1989 At the Department of Veterinary Surgery of the Ludwig Maximilian University, Munich, Germany, 132 femoral head and neck osteotomies were performed in dogs and 51 in cats. Eighty-one (44%) animals underwent follow-up clinical examination and radiography at an average of 4 years postoperatively, with 17 animals also undergoing motion analysis. Functional results were rated as good in 38% of cases, satisfactory in 20% and unsatisfactory in 42% of cases. However, 96% of owners were satisfied with the results of the operation. As shown by kinetic and kinematic measurements, despite pain relief after resection of the head and neck of the femur, functional impairment resulted from the operation in both small and large dogs. These disturbances were not noticeable during fast gaits.

Prevention of hip dysplasia

Prevention of hip dysplasia consists of balanced feeding of animals, correction of excess weight, as well as culling of breeding animals with hip dysplasia from breeding.

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Introduction

Femoral head and neck osteotomy (FCH) is a relatively simple procedure that has been the subject of many studies (1, 2, 4–8, 10–12, 18–24). Techniques and surgical approach vary, as do the results of the procedure. Some researchers have relied solely on owner assessment of outcome by completing questionnaires.

This study was conducted to evaluate the effectiveness of OGBC according to clinical examination and radiography of patients after surgery, performed at the Department of Veterinary Surgery, Ludwig Maximilian University, Munich, Germany. Some dogs were also analyzed for kinetics and kinematics, since the human eye is not able to correctly evaluate the full movement of a four-legged animal.

Removal of metal structures of the clavicle

Removing the plate from the collarbone is the logical conclusion of recovery after a fracture. Thanks to the presence of metal structures, patients no longer need to wear plaster casts and uncomfortable wooden splints. It is important to remove the metal part in time. It is better to do this in the same medical institution where the surgery was performed.

If the plate is not removed in time, the patient risks getting arthrosis in the articular area, bone growths - osteophytes, damage to muscle fibers from bone growths.

Materials and methods

Between 1978 and 1989, 132 dogs and 51 cats underwent OGBC surgery. This procedure was used in cases where joint preservation was not feasible or practical (Fig. 1). The most common indication in dogs was avascular necrosis of the femoral head due to Legg-Calvé-Perthes disease; most animals suffering from this disease weighed

In all cases, a craniolateral approach to the hip joint was used. After bending the joint capsule and cutting the round ligament, the limb was rotated 90° outward. An osteotome or vibrating saw was used to perform osteotomy of the femoral head. Sometimes the lesser trochanter was also cut off. To completely remove the caudal edge of the femoral neck, the osteotome or saw was held perpendicular to the long axis of the femoral neck (Fig. 3). The goal of this intervention was to create a smooth resection plane without bony protrusions. In most cases, the joint capsule was closed to create a layer of tissue between the acetabulum and the cutting surface of the femur after removal of the head and neck (Fig. 4) (17). Toward the end of the study, some animals received two additional sutures of durable, slowly absorbable material to secure the gluteal tendons to the insertion of the rectus femoris muscle to prevent caudodorsal displacement of the femur. The wound was sutured in the usual manner. Immediately after surgery, photographs were taken in the ventrodorsal projection to determine the osteotomy plane.

Follow-up examinations of 81 animals (66 dogs and 15 cats) were carried out 7 months to 10 years after surgery (average 4 years) in our clinic.

Rice. 1. Indications for osteotomy of the femoral head and neck in 132 dogs and 51 cats.

Rice. 2. Weight distribution of 132 dogs and 51 cats who underwent osteotomy of the femoral head and neck (the weight of 5 dogs is unknown).

Rice. 3. Orientation of the osteotome during femoral neck osteotomy.

Rice. 4. The joint capsule was positioned between the osteotomy site and the acetabulum to avoid pain due to contact of the two bony surfaces.

a) view of the hip joint in the transverse plane before resection;

b) view after removal of the head and neck of the femur;

c) closing the joint capsule;

d) ventral view of the acetabulum after closure of the joint capsule.

Clinical parameters assessed included lameness, muscle atrophy, pain with passive movement, crepitus, caudodorsal displacement of the femur, and range of motion. These objective variables were supplemented by the owners' assessment of the following indicators:

1. duration of postoperative symptoms;
2. duration of the postoperative recovery period;
3. leaning on the affected limb during slow gait, fast gait, after strenuous physical activity and in cold or damp weather;
4. subjective assessment of the success of surgical intervention.

Scores were assigned as follows:

1. good: no lameness, the animal fully relies on the limb at all gaits;
2. satisfactory: slight lameness, sometimes stiffness, sometimes lameness without support of the limb;
3. unsatisfactory: mild to severe persistent lameness, the animal often does not support the limb, lameness after exercise, lameness when trotting and/or galloping, lameness associated with weather.

In 67 cases (55 dogs and 12 cats), radiographs were taken immediately after surgery to assess the completeness of resection of the femoral neck with or without removal of the lesser trochanter and to ensure that there were no sharp bone edges along the osteotomy line. 17 dogs were also studied in a movement assessment laboratory (18, 19). Using a treadmill with four built-in load plates, the following kinetic parameters were assessed:

1. duration of the support phase (ms);
2. peak vertical support load (% of body weight);
3. slope of the support load curve (% of body weight/sec);
4. integral (% of body weight x sec).

Kinematic data were obtained using reflective markers placed on the iliac crest, greater trochanter, lateral femoral condyle, malleolus of the fibula, and tarsus during movement.

Indications for removal of fixatives

• fracture healing after osteosynthesis;
• low quality metal product;
• limited mobility of the joint next to which the plate is located;
• damage to the fastener or displacement from the installation site;
• desire to remove a postoperative scar;
• playing sports with heavy physical exertion - the presence of an implant can lead to a re-fracture;
• installing a plate for a child or teenager - its presence will interfere with normal bone growth;
• the presence of osteoporosis – an implant on the lower limb increases the risk of recurrent fracture;
• infection of deep tissues;
• the patient’s tendency to allergic reactions to a certain type of alloy or metal;
• suppuration at the site of the surgical wound;
• removal - as one of the stages of treatment.

results

Postoperative assessment showed shortening of the limb in 68 animals (84%) (caudodorsal displacement of the femur), muscle atrophy in 61 (75%) animals, a decrease in the range of motion during extension and abduction of the pelvic limb in 60 (74%), symptoms of lameness in 45 ( 60%), symptoms or pain with passive movement of the limb in 26 (32%) and crepitus in 8 (10%) animals (Table 1). The proportion of dogs weighing more than 15 kg was small, but this group tended to have worse outcomes than smaller patients. Subjective assessment showed that the fewest postoperative problems were observed in cats. Although clinical lameness was not detected in any cat, owners of 5 of 15 cats reported shortening their stride after physical activity, with changes in weather, fast or slow gaits, or after long periods of rest. According to the owners' observations, when the operated limb was loaded with a slow gait, 69 (85%) animals looked normal, and normal function with a fast gait was preserved in 52 animals (64%). Lameness after strenuous physical activity was observed in 19 patients (23%), and in cold weather - in 20 (24%) (Table 2).

However, 78 of 81 (96%) owners considered the outcome of the operation to be successful.

The average recovery period was 4 to 6 weeks in cats and small dogs and 7 to 9 weeks in dogs weighing more than 15 kg, although the period of postoperative lameness in the latter group was on average shorter than in smaller patients. Based on information obtained from owner questionnaires and the results of repeated clinical examination, functional results were assessed as good in 38% of cases, satisfactory in 20% and unsatisfactory in 42%. There was no correlation between body weight and functional outcome (Table 3). Preoperative symptoms persisted for an average of 5 weeks in animals with good results and for an average of 7 weeks in animals with poorer results (Table 4).

Postoperative radiographs showed complete osteotomy of the femoral head and neck in 40 animals (60%), half of which also underwent resection of the lesser trochanter (Table 5).

Table 1. Clinical signs in 66 dogs and 15 cats 7 months to 10 years (mean 4 years) after femoral head and neck osteotomy.

Table 2. Subjective information obtained from owners of 66 dogs and 15 cats after osteotomy of the femoral head and neck.

Table 3. Functional outcome depending on body weight.

Table 4. Functional outcome depending on the duration of postoperative symptoms.

The proportion of animals with satisfactory functional outcome was slightly greater after incomplete resection than after complete resection. X-rays taken during follow-up showed bone proliferation in the lesser trochanter in 34 animals (51%); 13 of these animals underwent resection of the lesser trochanter, while 21 did not (Fig. 5). Ossification in this area was noted in all cats (Fig. 6), while in dogs the incidence of osteophyte formation after complete and incomplete resection of the femoral head and neck was similar. There was no correlation between osteophyte formation and functional outcome.

On average, analysis of the movements of all dogs studied using kinetic data showed a shortening of the stance phase on the operated limb compared to the opposite limb (Table 6). In dogs weighing less than 15 kg, the peak vertical support load was slightly increased at the walk, but increased to 13% of body weight at the trot, while in dogs weighing more than 25 kg the load on the operated limb was lower by an average of 6% from body weight at both gaits. However, only one large dog has been tested on a treadmill while trotting. The slope of the ground load curve was used as a measure of force transfer, which was steeper in small dogs than in large dogs. The integral (total area under the curve), which is a measure of load impulse, was increased only in trot and decreased in other gaits due to a reduction in the duration of the stance phase (Fig. 7). The kinematic amplitudes of the hip, knee and tarsal joints varied significantly, but the graphs showed a characteristic pattern for each joint. The hip joint angle was slightly reduced in small dogs and markedly reduced in large dogs, indicating resistance to joint extension (Fig. 8).

The decrease in the angle of the hip joint was compensated mainly by extension of the tarsal joint.

Treatment of Legg-Calvé-Perthes disease in dogs

Treatment of Perthes disease in dogs can be conservative or surgical. Unfortunately, the first method rarely gives positive results. It involves keeping the pet in a cage for 4-6 months, a balanced diet and the use of anti-inflammatory drugs.

Veterinarians are confident that it is much more effective to carry out surgical treatment - resection arthroplasty. On the one hand, it relieves the dog of pain, and on the other, it completely restores the functions of the damaged limb.

Resection arthroplasty is performed on dogs of any age. Veterinarians in Moscow use different techniques to perform the operation, depending on the condition of the animal. After surgery, physical therapy and exercises are recommended to restore the pet's motor activity.

Discussion

The pioneers who pioneered the use of OGHA in veterinary medicine (21, 24) were pleased to find a promising, simple, and inexpensive method for the treatment of complex hip disorders. However, the use of OGBC as a panacea requires critical consideration. In our study, the effectiveness of OGBC was examined in a population limited to dogs and cats with predominantly chronic (weeks-long) symptoms (14, 16). Our results are consistent with those of Duff and Campbell, who found that progressive muscle atrophy and contractures associated with claudication were detrimental to surgical outcome (4). In contrast to total hip replacement, complete muscle recovery does not usually occur after OHHA (9, 15). The age of the animals did not correlate with the outcome, which is consistent with the data of Gendreau and Cawley (6).

Table 5. Radiographic and functional outcomes in 55 dogs and 12 cats immediately after femoral head and neck osteotomy surgery and at an average of 4 years after surgery.

*Follow-up examination was performed an average of 4 years after femoral head and neck osteotomy.

It was not possible to determine the effect of changes in surgical technique, in particular, interposition of the joint capsule or fixation of the greater trochanter with sutures, on the outcome retrospectively, since the medical records were incomplete. Evaluation of radiographs showed that removal of the lesser trochanter to relieve pain due to femoral-pelvic bone contact did not affect outcome; Bone proliferation in the area of ​​the resected or retained lesser trochanter did not correlate with functional outcome. The rate of unsatisfactory results after incomplete resection of the femoral neck was slightly higher than after complete resection, which is consistent with the results of Lee and Fry (10). However, the correlation between clinical presentation and radiographic findings was negligible, which is consistent with the findings of Duff and Campbell (5).

Of the 81 dogs and cats, 38% had limb function assessed as good on average 4 years after surgery, 20% as satisfactory, and 42% as unsatisfactory. These results may seem poor compared to other studies, but it should be noted that most of these studies were based on owner opinion (1, 2, 4, 7, 8, 10–12, 20–22, 24). The vast majority (96%) of our patient owners also rated the outcome as favorable.

Despite the lameness and lack of weight bearing on the limb, some dogs did not show any pain or limitation in range of motion that may be responsible for the lameness.

Passive movement of the operated limb caused pain in only about 33% of animals, while lameness was observed in 56% of cases, and more animals had other signs of dysfunction, such as muscle atrophy (Table 1). Consequently, the cause of lameness is not always obvious. In the absence of pain, the lameness may be mechanical due to scarring. The results of the movement analysis showed functional impairment in all 17 dogs after OHA. These animals showed a reduction in support contact time regardless of body weight, even if lameness was not noticeable on clinical examination. In small dogs, the vertical support force during stride was almost equal on both pelvic limbs, while in (a relatively small number of) large dogs this force was reduced on the operated limb, presumably due to the animal's desire to spare it.

Rice. 5. X-rays of an 8-month-old, 5-kg Jack Russell Terrier with Legg-Calvé-Perthes disease. Ventrodorsal view of the pelvis:

a) before surgery;

b) immediately after surgery with complete resection, including the lesser trochanter;

c) 8 months after surgery, slight proliferation of bone tissue without deterioration of function.

Rice. 6. X-rays of a two-year-old cat weighing 3.5 kg with repeated dislocation of the hip joint. Ventrodorsal view of the pelvis:

a) before surgery;

b) immediately after surgery with incomplete resection of the lesser trochanter; pronounced proliferation of bone tissue in the area of ​​the lesser trochanter without deterioration in function.

With the exception of one dog, kinetic studies at trotting have only been performed in small dogs; the results showed increased load on the operated limb. This phenomenon was noted by Dueland et al in a comparative study of total hip replacement and OGHA, which led the authors to question the superiority of hip replacement over OGHA in quadrupeds (3). However, gait analysis in people with shortened limbs suggests that the increased load is caused by a shift in the center of gravity toward the shortened side (13).

In our study, owners often noted that dogs avoided trotting. During trotting, pairs of limbs move diagonally towards each other, and at some point one of the pelvic limbs bears approximately 60–80% of the body weight. It is unknown whether avoidance of the trot is associated with the occurrence of this short-term severe loading or with a decrease in the ability to extend the hip joint. Based on our kinematic data, dogs with a reduced range of motion in the hip joint after OHA compensate for this mainly due to greater extension at the tarsal joint.

In conclusion, the present study revealed discrepancies between the results of objective clinical assessment and subjective observations of owners of animals who have undergone OHBI. This clearly shows that the effectiveness of surgical treatment should not be determined using questionnaires. The currently accepted view that small dogs compensate better than large dogs for the effects of OHCA should be reconsidered in light of our results from the movement analysis. Reduction of pain after OHHA comes at the expense of some impairment of limb function, even in small dogs, where lameness may be difficult to detect with the naked eye due to their rapid movements. Thus, OHA should be limited to exceptional circumstances when joint preservation is not possible or infection or other contraindications preclude joint replacement, even in small dogs (16).

Table 6. Results of motion analysis of 17 dogs after osteotomy of the femoral head and neck.

Rice. 7. Ground force curve of a 5.8 kg Yorkshire terrier 6 years after osteotomy of the right femoral head and neck during a) walking and b) trotting. Y axis: N = Newtons; X-axis: time in seconds; F1 = right thoracic limb; F4 = left thoracic limb; F2 = right pelvic limb; F3 = left pelvic limb.

Rice. 8. Schematic representation of the hip and stifle angle of a 44.5 kg Saint Bernard dog 6 years and 7 months after osteotomy of the right femoral head and neck; a) right pelvic limb, b) left pelvic limb.

Green: hip angle; red: knee joint angle; y-axis: angle (degrees); x-axis: time (sec).

Removal of spinal metal structures

Spinal surgeries using metal structures are prescribed in extreme cases when conservative treatment does not give the desired result. Only in isolated cases is it necessary to remove the metal structure due to the need for re-operation on a fixed spinal motion segment or if unforeseen complications occur.

There are 2 main techniques for fixing the spine: rigid and dynamic fixation. In the first case, the metal structures used provide complete immobility of unstable vertebrae. The only drawback of such systems is that the patient’s physical capabilities are limited by the implants themselves.

Dynamic fixation systems are more expensive and require more professionalism of the surgeon.

Literature:

1. Berzon JL, Howard PE, Covell SJ, et al. A retrospective study of the efficacy of femoral head and neck excisions in 94 dogs and cats. Vet Surg 1980; 9:88–92.
2. Bonneau NH, Breton L. Excision arthroplasty of the femoral head. Canine Pract 1981; 8, 2: 13–25.
3. Dueland R, Bartel DL, Antonson E. Force-plate technique for canine gait analysis of total hip and excision arthroplasty. J Am Anim Hosp Assoc 1977; 13, 5: 547–552.
4. Duff R, Campbell JR. Long term results of excisional arthroplasty of the canine hip. Vet Rec 1977; 101: 181–184.
5. Duff R, Campbell JR. Radiographic appearance and clinical progress after excision arthroplasty of the canine hip. J Small Anim Pract 1978; 19, 8: 439–449.
6. Gendreau C, Cawley AJ. Excision of the femoral head and neck: The long-term results of 35 operations. J Am Anim Hosp Assoc 1977; 13, 5: 605–608.
7. Hofmeyr CFB. Excision arthroplasty for canine hip lesions. Mod Vet Pract 1966; 47, 2: 56–58.
8. Junggren G.L. A comparative study of conservative and surgical treatment of Legg-Perthes' disease in the dog. Anim Hosp 1966; 2:6–10.
9. Kosfeld HU. Der totale Hüftgelenkersatz beim Hund. Klinische, röntgenologische und ganganalytische Erhebungen in den Jahren 1983 bis 1993. Diss med vet, München 1996.
10. Lee R, Fry PD. Some observations on the occurrence of Legg-Calvé-Perthes' disease (Coxaplana) in the dog, and an evaluation of excision arthroplasty as a method of treatment. J Small Anim Pract 1969; 5:309–317.
11. Lippincott C.L. Excision arthroplasty of the femoral head and neck utilizing a biceps femoris muscle sling. Part Two: The caudal pass. J Am Anim Hosp Assoc 1984; 20: 377–384.
12. Lippincott C.L. A summary of 300 surgical cases performed over an 8 year period: excision arthroplasty of the femoral head and neck with a caudal pass of the biceps femoris muscle sling (Scientific Meeting Abstract). Vet Surg 1987; 16, 1: 96.
13. Lüttschwager P. Zum Einfluä statischer und muskulärer Dysbalancen auf die Bewegungsasymmetrie beim Laufen mit unterschiedlichen Geschwindigkeiten. Dipl.-Arbeit 1992, Sporthochschule Köln.
14. Matis U, Waibl H. ProximaIe Femurfrakturen bei Katze und Hund. Tierärztl Prax 1985; Suppl.1: 159–178.
15. Matis U, Knobloch S, Off W. Der Hüftgelenkersatz beim Hund. 9 Jahre Erfahrung an der Chirurgischen Tierklinik der Ludwig-Maximilians-Universitat München. 1. Seminar des AMC New York, Tegernsee, 1992 (Abstract).
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17. Matis U, Schebitz H, Waibl H. Zugang zum Hüftgelenk von kraniolateral. In: Operationen an Hund und Katze, 2. Aufl. Schebitz H, Brass W (Hrsg.) Berlin: Blackwell.
18. Off W. Klinische und ganganalytische Erhebungen zur Resektionsarthroplastik des Hüftgelenks bei Hund und Katze in den Jahren 1978 bis 1989. Diss med vet München 1993.
19. Off W, Matis U. Ganganalyse beim Hund. Teil 2: Aufbau eines Ganglabors und bewegungsanalytische Untersuchungen. Tierärztl Prax 1997; 25: 303–311.
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Who is indicated for hip replacement surgery?

These are patients who have varying degrees of lameness in the hind limbs that is not relieved by anti-inflammatory drugs.

All candidates undergo an orthopedic and neurological assessment. It is very important to exclude neurological problems that may resemble orthopedic ones in their clinical course. Orthopedic problems necessarily exclude rupture of the anterior cruciate ligament and pathology of the hock joint. Rupture of the anterior cruciate ligament in dogs is the leading cause of pelvic limb lameness. The youngest age for hip replacement is 10 months. Today, there are practically no restrictions on the body weight of patients. There are different sizes of implants that can suit toy and giant breeds.