Juvenile pubic symphysiodesis is a recently developed surgical procedure, described for the first time in 2001 (Dueland), performed on puppies to contrast the development of early forms of hip dysplasia. Performed at the right time, and with the right indications, pubic symphysiodesis can improve joint congruity; the result is achieved with a spontaneous acetabular ventroflexion promoted by arresting the growth of the pubic rami of the pelvis by means of the cauterisation of the pubic symphysis; the subsequent residual growth of the animal allows for an increased acetabular coverage of the femoral heads. Juvenile pubic symphysiodesis, which is considered as an early-age treatment for basically dysplastic puppies, has proven to be, in well selected cases, an early and minimally-invasive surgical option able to correct or effectively limit the development of hip dysplasia and therefore prevent the secondary arthritic alterations caused by dysplasia. As previously mentioned, a decreased slope of the acetabular roof is achieved by arresting pubic rami growth through the cauterisation of the pubic symphysis growth plate, which, in combination with the normal growth of the iliac bones and hence of the dorsal part of the acetabula, leads to a ventral traction and consequent ventrolateral rotation of both acetabula, thus improving joint congruity and acetabular coverage (Fig. 1).
Pubic symphysiodesis cannot be performed indiscriminately on every puppy presenting early signs of hip dysplasia; a rigorous selection of patients is in fact necessary, aimed at excluding from surgery both minimally affected dogs, in which the prognosis can be improved by just optimising environmental conditions, and subjects with a far too advanced stage of hip displasya, in which such surgical approach would not be able to stop the progression of the disease.
Similarly to triple and dual pelvic osteotomy (TPO/DPO), symphysiodesis results in a ventral rotation of the acetabulum, which allows to contrast the subluxation forces present within the hip joint; goal of the approach is to re-establish joint congruity, as well as to decrease or to arrest the progression of arthritis. Juvenile pubic symphysiodesis, like other surgical procedures used to stop or limit the development of dysplasia, implies the exclusion of the dog from breeding programmes, as the phenotype is modified by surgery. Notwithstanding the improvement in the dog’s life and welfare, pubic symphysiodesis cannot obviously modify the gene pool responsible for the development of the disorder. Consequently, although these dogs exhibit normal or almost normal hips once skeletal development is completed, they must be excluded from breeding. Before surgery, an informed consent of the owner is therefore always required.
PATIENT SELECTION
Juvenile pubic symphysiodesis has to be performed within a strict time window and under precise indications. Puppies eligible for juvenile pubic symphysiodesis are between 14 to 18 weeks of age and present signs of susceptibility to hip dysplasia, such as a predisposition to subluxation evidenced by a positive Ortolani sign, hip reduction angle (HRA) values between 15° and 35° and an angle of subluxation (AS) between 0° and 15°, DARA between 7° and 10° with a preserved rim and joint laxity with a distraction index (DI) ranging between 0,4 e 0,8. For those puppies whose values are just within the limits of the indications reported above, the prognosis varies according to existing lesions and to post-operative management. Age plays a very important role in the outcome of the operation. The right time window for surgery differs according to the breed; giant breeds (e.g. Newfoundland, Dogue de Bordeaux, Bernese Mountain Dog, Saint Bernard) are eligible for juvenile pubic symphysiodesis up to 20-22 weeks of age, whereas medium to large size breeds (e.g. Labrador Retriever, Rottweiler, German Shepherd) should be operated on within 18 weeks in order to achieve clinical effectiveness.
SURGICAL PROCEDURE
Juvenile pubic symphysiodesis is a minimally invasive surgery; a small skin incision (4-5 cm), near the pubic area, allows to cauterise the cartilage growth plate of the cranial part of the pubic symphysis, in proximity of the pubic rami (Fig. 2).
After a partial disinsertion of the prepubic tendon from the central part of the pubis, a 2-3 cm segment of the pubic symphysis is exposed, in proximity of the pubic rami. Before proceeding with cauterization, using the electrocautery needle, a thin autoclavable wooden spatula must be inserted at least 3 cm caudally beneath the cranial part of the pubis, in order to protect the abdominal organs from the electrocautery blade and avoid accidental urethral or rectal lesions (Fig. 3). Cauterisation of the growth plate is done with a full thickness insertion of the electric cautery needle or thin blade into the pubic symphysis, until coming into contact with the wooden spatula. The insertion of the needle/blade is repeated over multiple points, at a distance of about 3-4 mm one from the other, with the electric power activated for a duration of 4-5 seconds, in order to induce thermal necrosis of the germinal component of the growth plate, always in proximity of the pubic rami. In the more cranial part of the symphysis, where the section is wider, cauterisation is done with two rows of points on each side, while in the more caudal part, where the symphysis is narrower, it is done only in the central area. In order to avoid thermal damage to the surrounding tissues, abundant saline irrigations are necessary between each step of cauterisation.
An alternative procedure, described by Dueland, consists in the sequential, full thickness insertion of needle electrodes into different points of the pubic symphysis, at a distance of 2-3 mm one from the other, and using a power of 40 watts for the duration of 10-20 seconds; this approach avoids the burning of tissues as it generates a heat halo surrounding the electrode which is sufficient to thermally necrotise the cartilage growth plate; tissue combustion is avoided and no smoke is generated, as is instead the case with the previously described method. The surgical procedure is completed with the suturing of the pre-pubic tendon to the periosteum, of the subcutis and cutis.
Postoperative recovery, at least for the initial two months, consists in restricting the exercise freedom of the puppy, in order to try to revert the tendency to subluxate of the hip joints. During such period, puppies should not be allowed to roam freely in large open spaces, preferring instead fast-paced walks, on a leash, in order to promote muscle toning and better contrast joints laxity.
COMPLICATIONS
Both intraoperative and postoperative complications can occur. Intraoperative complications include possible urethral and rectal lesions, if the abdominal organs are not adequately protected. Such lesions are potentially extremely severe and must be avoided with the utmost care. Cauterisation of the more caudal part of the symphysis pubis can cause irritation of the obturator nerve, which crosses the obturator foramen; this may happen if the cautery-electrode is not kept at the centre of the symphysis and if it is used too close to the obturator foramen. When using an electric scalpel with a neutral plate in contact with the dog’s back, if the contact area is not broad enough and if a conductive gel is not used, skin burns in the major contact areas may result. This possible complication may be avoided by using a radio frequency electrosurgical unit, as in this case the neutral plate is not in contact with the patient. A postoperative painful oedema may occur if tissues are not cooled with sterile saline solution between each step of cauterisation.
Postoperative complications include a lack of efficacy of the procedure due to a failure of the cauterisation technique in achieving a bone fusion of the symphysis pubis; this can be confirmed with follow-up X-rays at 5-6 months, when the bone fusion should be complete (Figs. 4 and 5).
The lack of efficacy in preventing hip joint subluxation and the arthritic progression of dysplasia may also depend on a wrong patient selection, with the inclusion of subjects in which hip dysplasia is too advanced to be treated with juvenile pubic symphysiodesis. An inadequate postoperative course, with an excessive freedom in terms of exercise and play, may worsen the hip subluxation of the puppy before it may be contrasted by a sufficient acetabular rotation. In the case of an unwanted pregnancy, dystocia should also be considered as a postoperative complication, as pubic symphysiodesis also causes a narrowing of the pelvic canal. Finally, there is also the possibility that the dog may be voluntarily used for breeding, notwithstanding the phenotype change resulting from surgery, either because of fraud or simply because the new owner has not been informed about the previous surgical intervention.
Suggested readings
- Slocum B, Slocum TM. Hip – Diagnostic Tests. In: Current techniques in small animal surgery. Ed Bojrab MJ, Ellison GW, Slocum B. Baltimore: Williams&Wilkins, 1998; pp 1127–1144.
- Slocum TD, Slocum B. Radiographic character- istics of hip displasia. In: Current techniques in small animal surgery. Bojrab MJ, Ellison GW, Slocum B (eds). Williams&Wilkins, Baltimore, 1998, pp 1145–1150.
- Dueland RT, Patricelli AJ, Adams WM, Linn KA, Crump PM. Canine hip dysplasia treated by juvenile pubic symphysiodesis. Part II: two year clinical results. Vet Comp Orthop Traumatol. 2010; 23(5): 318-25. Epub 2010 Aug 25. Erratum in: Vet Comp Orthop Traumatol.2010; 23(6): 472
- Dueland RT, Adams WM, Patricelli AJ, Linn KA, Crump PM. Canine hip dysplasia treated by juvenile pubic symphysiodesis. Part I: two year results of computed tomography and distraction index. Vet Comp Orthop Traumatol. 2010; 23(5): 306-17. Epub 2010 Aug 25. Erratum in: Vet Comp Orthop Traumatol. 2010; 23(6): 472.
- Bernardé A. Juvenile pubic symphysiodesis and juvenile pubic symphysiodesis associated with pectineus myotomy: short-term outcome in 56 dysplastic puppies. Vet Surg. 2010 Feb; 39(2): 158-64.
- Vezzoni A, Dravelli G, Vezzoni L, De Lorenzi M, Corbari A, Cirla A, Nassuato C, Tranquillo V. Comparison of conservative management and juvenile pubic symphysiodesis in the early treatment of canine hip dysplasia. Vet Comp Orthop Traumatol. 2008; 21(3): 267-79.
- Manley PA, Adams WM, Danielson KC, Dueland RT, Linn KA. Long-term outcome of juvenile pubic symphysiodesis and triple pelvic osteotomy in dogs with hip dysplasia. J Am Vet Med Assoc. 2007 Jan 15; 230(2): 206-10.
- Patricelli AJ, Dueland RT, Adams WM, Fialkowski JP, Linn KA, Nordheim EV. Juvenile pubic symphysiodesis in dysplastic puppies at 15 and 20 weeks of age. Vet Surg. 2002 Sep-Oct; 31(5):435-44.
- Dueland RT, Adams WM, Fialkowski JP, Patricelli AJ, Mathews KG, Nordheim EV. Effects of pubic symphysiodesis in dysplastic puppies. Vet Surg. 2001 May-Jun; 30(3): 201-17.