PMC9926365_01
Case 1. (a) Anteroposterior and (b) Zanca preoperative radiographs showing right clavicular mal- union, bone loss of the medial clavicle, surrounding heterotopic ossification and sterno-osseous pseudarthrosis. The scapula is protracted and in a fixed lateral displacement.
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There was malunion of the residual medial clavicle through a previous transclavicular graft tunnel, and heterotopic ossification between the medial extent of the remaining clavicle and the first rib and sternum with a distal pseudarthrosis, causing the persistent scapular ptosis (Figure 1).
Case 1. Implant design. A custom cemented medial clavicle replacement with a hydroxyapatite-coated rough collar region (Stanmore Implants Worldwide, Elstree, London, United Kingdom). The custom metallic sternal tray (Stanmore Implants Worldwide, Elstree, London, United Kingdom) was fixed with two 3.5 mm interlaminar cortical screws into the cancellous bone of the manubrium sterni, and the UHMWPE liner was cemented into the tray.. UHMWPE: ultra high molecular weight polyethylene.
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A custom cemented medial clavicle replacement with a hydroxyapatite-coated rough collar region (Stanmore Implants Worldwide, Elstree, London, United Kingdom) was implanted (Figure 2). The custom metallic sternal tray (Stanmore Implants Worldwide, Elstree, London, United Kingdom) was fixed with two 3.5 mm interlaminar cortical screws into the cancellous bone of the manubrium sterni (Figure 2), and the ultra high molecular weight polyethylene liner was cemented into the tray.
PMC9926365_02
Case 2. (a) Three-dimensional reconstruction of the preoperative CT images showing osteonecrosis of the medial end of the left clavicle, loss of the normal SCJ articular surfaces with deformity, and axial rotation of the clavicle at the nonunion site; (b) Implant design. The medial spherical 'head' was of smaller dimension than in the first case. Perforations were designed in the clavicle implant to facilitate reconstruction of both the intrinsic and extrinsic ligaments. The prosthesis was coated with hydroxyapatite to facilitate soft tissue (muscle) adherence; (c) Detail of the sternal tray and liner: note the perforations in the tray for the attachment of the polyurethane mesh hood (neo-'capsule'). These facilitated attachment of remaining capsular tissue and reinforcement with the mesh hood. The sternal tray was press-fit into the instrumented sternal resection and fixed with intralaminar manubrial 3.5 mm cortical screws.
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An implant, based on that used in the former case, was designed with the addition of perforations in the sternal metal tray to facilitate the attachment of a polyurethane mesh hood (Artelon, Lavendar Medical, United Kingdom) posteriorly, medially and anteriorly to reconstruct the intrinsic capsular ligaments for improved stability (Figure 3).
Case 2. Anteroposterior (a) and Zanca (b) radiographic views at the 6-month postoperative review. Both prostheses remain secure, and the SCJ remains enlocated 2 years after implantation.
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Radiographs showed no concerns regarding the sternal prosthesis while there was a 2 mm lucent zone at the tip of the clavicular prosthesis the significance of which was uncertain (Figure 4).