Alexander (1992) ascribed hip dysplasia in dogs a biomechanical disease, represented by the discrepancy between primary muscular mass and rapid bone growth. In a study involving young dogs, Cardinet (1997) suggested that pelvic muscle abnormalities were related to the development of the hip dysplasia.

Sumner-Smith (2000) further elaborated that hip dysplasia is a syndrome related to abnormal musculoskeletal development predicated on a genetic predisposition, but influenced by other factors, such as rapid growth, environment, and a rich protein diet.

Since Schnelle first reported hip dysplasia in dogs in 1937, there are now more studies regarding this disease than of any other pathology related to small animals orthopedics. However, such authors are not able to assert the exact etiology of the disease. There is evidence that there is a polygenic effect responsible for primary lesion in the cartilage and muscles that provide support to the hip joint region (Smith, 1997), proven only by heredity.

One of the best accepted hypothesis currently that dogs affected with disease are born with a normal hip joint articulation and due to genetic factors, muscular strength is insufficient to maintain the femoral head in the acetabulum, thus causing laxity of the hip joint articulation and leading to articular incongruity and later articular degeneration (Numamaker, et al 1973; Alexander, 1992; Charette et al 2001).

Treatment of the dogs with hip dysplasia can be both conservative and/or surgical. The conservative treatment is based in a triad protocol including 1) pharmacologic treatment, which is aimed at pain relief and subsequent amelioration of discomfort caused by articular inflammation, by using narcotics, steroids and non-steroidal anti-inflammatories; 2) body weight control, to decrease articular overload; and 3) physiotherapy, were controlled exercise program helps maintain muscle tone and improves range of motion (Martinez, 2001).

Surgical treatments such as, pectinectomy, corrective osteotomies, excision of the femoral head, total hip replacement and several other techniques each have merits, but are not universally successful in all dogs (Matis, 2000; Bollinger et al 2002; Kinzel et al 2002).

Total hip replacement is currently considered the optimum treatment for large and giant breed dogs affected with hip dysplasia (Olmstead, 1995a, Matis, 2000; Sumner-Smith, 2000; Kinzel et al 2002).

The hip joint capsule denervation is an innovative technique in dogs reported first by Kinzel and Küpper (1997). These authors performed a selective neurectomy of the sensory fibers of the joint capsule with the sole objective of providing hip joint analgesia via denervation.

Treatment of hip dysplasia by means of denervation is based on techniques previously described for use in human patient and which is therapeutically successful, mainly for chronic articular diseases of the hands (Foucher et al, 1998).

Kinzel et al (2002b) reported good results with cranial denervation of the acetabular margin in 117 dysplastic dogs. In that same year these author published the results of 10 years of experience using the denervation technique that was performed in 269 dogs, with 92% in lameness improvement and pain remission (Kinzel et al, 2002a).

The study of the periosteal nerve fiber density of the acetabular margin conducted by Schmaedecke & Ferrigno (2004), reveal that the cranial and dorsal acetabular margin had the approximated the same nerve fiber density, and the caudal aspect of the acetabular margin had less density.

After the anatomical study, Ferriggno et al (20004) propose a cranial and dorsal denervation of the acetabular margin, and reported 966% of good results in lameness improvement and pain remission in a clinical study in 1667 dogs.

Surgical Technique

After trichotomy and standard operative preparations on both sides, cutaneous incision on the lateral side of the pelvis on only one articulation will be executed, beginning at the tip of the iliac and running down to the greater trochanter of the femur. Afterwards, the dissection of the underlying tissues, localization, isolating and removal of thee femoral bicep muscles, middle gluteus and tensor fascia lata will be performed. Hommman's retractor will be placed on the dorsal margin of the iliac so that with the result of the lever, the middle gluteus muscle can be cranially retracted to have access to the cranial-dorsal side of the acetabulum. With a curette the entire periosteum will be lifted at the cranial acetabular and dorsal margin, up to the osseous cortical.

Click on the image to see a larger view.

Figure 1. Approach of the ileal body for denervation.

References

1.  Alexandeer JW. The pathogenesis of canine hip dysplasia The Veterinary Clinics of North America, v.22, n .3, p.503-13, 1992.

2.  Foucher G, Long Prretz P, Erhaart L. Joint denervation, a simple response to complex problems in hands surgery. Chirurgie, v.123, n.2, p.183-8, 19988.

3.  Kinzel S, Küpper W. Operationsteechick und klinnische erfahrunngen zur hüftg elenksdenervaation beim hund. Der prakt ische Tierarzzt Collegium Veterinarium. v.27, p.26-299, 1997.

4.  Kinzel SS, Hein S, von Scheveen C, Küpper W. 10 Jahre erfahru ng mit der denervation der hüftgelenkkkapsel zur theerapie der hüfttgelenkdysplassie und arthrosse des hundess. Tierärztl. Wschr. v. 115, p.53-56, 2 002a.

5.  Kinzel S, von Scheveen C, Bueckker A, Stopiinski T, Küpper W. Clinical evaluation of denervation of the canine hip joint capsule: a retrospective study of 117 dogs. Veterinary Comparative Orthopedic and Traumatology. v. 15, p .51-56, 2002bb.

6.  Martinez SA. Balanced management of osteoarthritis in companion animals. In: Clinical Perspectives on Canine Joint Disease. p.32-37. NAVC, Orlando, 2001.

7.  Numamaker DM, Biery DN, Newton C.D. Femoral neck antiversion in the dog: Its radiographic measurements. Journal of American Veterinary Radiology Society, v.14, p.45-48, 1973.

8.  Sumner-Smith G. Hip dysplasia, World Small Animal Veterinary Association Scientific proceedings World Congress Amsterdam 2000, p.382-83, 2000.

9.  Schmaedecke A, Saut JPE, Ferrigno CRA. A quantitative analysis of the nerve fibers of the periosteal acetabulum of dogs, Veterinary and Comparative Orthopaedics and Traumatology. v.4, p.,2008

10. Ferrigno CRA, Schmaedecke A, Ferraz VCM. Abordagem cirúrgica inédita para denervação acetabular de cães. Pesq. Vet. Bras., v.27, n.2, p. 61-63, 2007. (doc I.1.35)

11. Ferrigno CRA, Schmaedecke A, Oliveira LM, D'avila RS, Yamamoto EY, Saut. Denervação acetabular cranial e dorsal no tratamento da displasia coxofemoral em cães: um ano de evolução de 97 casos1. Pesquisa Veterinária Brasileira 28(8):333-340, 2007.