Case report: Three-dimensionally printed patient-specific acetabular cage for revision surgery of aseptic loosening in a dog with micro total hip replacement

Abstract

A 2-year-old castrated male Pomeranian dog was presented for regular follow-up after micro total hip replacement (mTHR) 16 months prior to presentation. Clinically, the dog did not show any noticeable lameness of the left hindlimb, except for external rotation during walking. However, radiographic findings, namely rotation and medialization of the acetabular cup with a periprosthetic lucent line and bone formation medial to the acetabulum, were interpreted as aseptic loosening of the acetabular component. Because the dog was incompatible with the conventional THR revision method owing to severe bone defects in the acetabulum, a patient-specific titanium acetabular cage prosthesis with biflanges and four cranial and one caudal screw hole was designed for revision surgery. A custom-made acetabular cage was prepared, and it had a 12-mm polyethylene cup fixed with polymethylmethacrylate bone cement and positioned in the acetabulum. After the custom-made acetabular cage was anchored to the pelvic bone with the five cortical screws, reduction of the prostheses was achieved smoothly. The dog showed almost normal limb function without external rotation of the left hindlimb 2 weeks postoperatively. Bone remodeling and stable implant position were noted on radiographic images 3 years after revision surgery, with no evidence of loosening. Based on the clinical outcomes, the use of a custom-made acetabular prosthesis can be an effective treatment option for revision arthroplasty in acetabula with severe bone loss and structural changes in small-breed dogs.

Use of a custom‐made acetabular cage to treat aseptic loosening following cemented total hip replacement in a giant breed dog

“…[16][17][18]21 Treatment techniques rely on the extent, the localisrration and the severity of bone loss. 9,[16][17][18][19]21 In our case, deficiency of the medial acetabular medial wall and loss of the caudal pillar were the major concerns. These precluded several surgical options for revision surgery.…”

“…An acetabular reinforcement ring was considered an appropriate option, as the goals of the reconstruction were to provide stability for the acetabular component and restore the centre of rotation of the hip. 2,9,21,22 Different devices have been developed in human medicine with different components, such as acetabular shell, anti-protrusion cage, flanges and/or hook among others. 18,21,23,24 The custom-made implant we used was designed based on the Burch-Schneider ring in human medicine, and on previous reports published in veterinary medicine showed satisfactory outcomes.…”

“…[1][2][3][4][5][6] Complication rates after THR range from 7% to 20%, including coxofemoral luxation, infection, septic or aseptic implant loosening, periprosthetic fractures, implant failure, acetabular cup displacement, pulmonary embolism, extraosseous cement granuloma formation, sciatic nerve lesion. [7][8][9][10][11][12][13] Debonding at the cement-bone and implant-cement interfaces can occur through septic and aseptic mechanisms including bone resorption. 8,9,14,15 The ensuing instability within the acetabular cup results in lameness.…”

“…[7][8][9][10][11][12][13] Debonding at the cement-bone and implant-cement interfaces can occur through septic and aseptic mechanisms including bone resorption. 8,9,14,15 The ensuing instability within the acetabular cup results in lameness. 15,16 Depending on the type of acetabular cup, stability relies on supportive structures, including the dorsal acetabular rim, cranial and caudal bone pillars and the medial acetabular wall, in addition to intrusion of cement into keyholes made into the ilium.…”

“…22 Finally, a Pomeranian dog was treated with a patient-specific acetabular cage for an aseptic loosening 16 months after a micro-THR with excellent outcomes 3 years postoperatively. 9 Acetabular reinforcement implants may be considered as treatment in dogs for acetabular defects.…”