The accuracy of positioning of a custom-made implant within a large acetabular defect at revision arthroplasty of the hip

Abstract

We evaluated the accuracy with which a custom-made acetabular component could be positioned at revision arthroplasty of the hip in patients with a Paprosky type 3 acetabular defect. A total of 16 patients with a Paprosky type 3 defect underwent revision surgery using a custom-made trabecular titanium implant. There were four men and 12 women with a median age of 67 years (48 to 79). The planned inclination (INCL), anteversion (AV), rotation and centre of rotation (COR) of the implant were compared with the post-operative position using CT scans. A total of seven implants were malpositioned in one or more parameters: one with respect to INCL, three with respect to AV, four with respect to rotation and five with respect to the COR. To the best of our knowledge, this is the first study in which CT data acquired for the pre-operative planning of a custom-made revision acetabular implant have been compared with CT data on the post-operative position. The results are encouraging.

Additive manufacturing in orthopaedics: Clinical implications

“…4 Revision surgery and limb-reconstruction surgery are technically demanding. 1,[10][11][12] There are many problems such as distorted soft tissue and bony anatomy, variable bone stock and quality, and prosthetic placement. All of these difficulties were present in this case.…”

“…2,13,14 In response to these two problems, customised implants with the addition of plates, shaped specifically for the altered anatomy, and jigs to aid in the accurate placement of screws, have been developed. 2,12 In the case report described above the goals of the surgery were to provide a pain-free, stable hip joint with an improved range of motion to allow for prosthetic use. The problems faced included the patient's dysplastic acetabulum and soft tissue contracture.…”

Additive manufactured metallic implants for orthopaedic applications

“…The early case series are encouraging in various field of complex orthopaedic procedures, like bone tumour surgery [8][9][10]14], revision hip surgery [6,7,11], spinal implants [12][13][14] and trauma fracture fixation and reconstruction [15,16]. The additive manufacturing technology may address the reconstructive challenges that off-the-shelf, standard implants cannot provide for implant-size or disease-specific surgical requirement.…”

“…The early clinical results of the new technique were satisfactory in limb function and implant alignment in two studies [6,7]. Patients' CT images were first analysed with reference to bone quality and geometry of the acetabular bone defects (Fig.…”

“…The standard traditional implants may not address the reconstructive challenges such as severe bone deformity or bone loss after implant loosening and bone tumour resection. With the advent of digital technologies in medical imaging, computer programming in three-dimensional (3D) modelling [1] and computer-assisted tools [2][3][4][5] in precise implant placement, there has been increasing interest in using patientspecific implants for complex orthopaedic reconstruction [6][7][8][9][10][11][12][13][14][15][16].…”