To begin, identify the tip of the greater trochanter, the cranial border of the proximal femur, the iliac wing, and the ischiatic tuber on the anesthetized dog. Then draw a line to make a skin incision. Perform the Ortolani subluxation test to confirm hip subluxation before making an incision.
Incise the skin sharply with a surgical knife, starting from the cranial dorsal iliac spine. Then turn ventrally along the cranial border of the proximal femur and stop distally to the greater trochanter. Make an incision through the subcutaneous fat down to the fascia.
Sharply separate and incise the superficial leaf of the fascia lata muscle along the cranial border of the biceps femoris muscle. Retract the biceps femoris muscle caudally. After identifying the fatty triangle, separate it with blunt-tipped dissecting scissors and index finger to provide access to deeper layers.
Using a surgical knife, incise the intermuscular septum between the superficial gluteal muscle, the middle gluteal muscle, and the tensor fascia lata muscle. With a handheld retractor, separate and retract the superficial and middle gluteal muscles dorsally to expose the insertion of the deep gluteal muscle. Use blunt-tipped dissecting scissors to undermine the deep gluteal muscle close to the greater trochanter.
Pre-place a stay suture on the deep gluteal tendon approximately one to 1.5 centimeters proximal from its insertion on the greater trochanter. Using a surgical knife, perform a complete deep gluteal tenotomy close to the bone. Use blunt-tipped dissection scissors to free the deep gluteal muscle from the underlying joint capsule.
Then with the help of the periosteal elevator and index finger, subperiosteally elevate the deep gluteal muscle from the ileum and retract it dorsally. Using a periosteal elevator, partially free the iliacus muscle from the caudoventral border of the iliac shaft, and identify the insertion of the rectus femoris muscle. Remove all remaining soft tissue from the exposed iliac shaft for accurate positioning of the 3D hip implant.
Scratch the periosteum to stimulate bone ingrowth for secondary implant fixation. Identify the articularis coxae muscle, caudal to the rectus femoris muscle overlying the joint capsule. Check the 3D hip implant before positioning and check the locking mechanism of the drill guide on the implant.
Confirm a positive Ortolani subluxation test before implantation. Fit the 3D hip implant into the iliac shaft, ensuring the implant's flange hook under the ventral border of the exposed caudoventral iliac shaft, just cranial to the bony prominence. Check that the rim extension part of the implant overlays the craniodorsal part of the hip joint capsule without capturing any deep gluteal muscle.
Verify the implant position by visualizing and probing for optimal bone contact in all four exposed screw holes. Then confirm the absence of space between the iliac flange and the caudoventral iliac shaft. Drill the hole for the first screw.
Then measure the screw length and temporarily fix the implant in the desired position with one titanium self-tapping locking screw. After intraoperative fluoroscopy of the hip joints, ensure that the curvature of the rim extension part of the implant is congruent with the curvature of the femoral head and acetabular rim. Once correct positioning is confirmed, insert three titanium self-tapping locking screws in the remaining screw holes to fix the implant to the ileal shaft.
Next, execute flexion, extension, and abduction movements of the hip joint to check for femoral head or neck impingement. Perform the Ortolani subluxation test to confirm the reversal of hip laxity. Reattach the cut ends of the insertional tendon of the deep gluteal muscle using a locking loop suture pattern and one to two mattress synthetic, absorbable, monofilament sutures.
Repair the gluteal fascia and tensor fascia lata in a simple interrupted pattern. Close the subcutaneous tissue with an absorbable suture and skin with a non-absorbable suture in a simple interrupted pattern. To confirm the implant positioning and screw placement, perform postoperative imaging, consisting of CT scan of the hips or hip orthogonal radiographs in lateral oblique, and ventral/dorsal views.
