Arthrodesis and Defect Bridging of the Upper Ankle Joint with Allograft Bone Chips and Allograft Cortical Bone Screws (Shark Screw®) after Removal of the Salto-Prosthesis in a Multimorbidity Patient: A Case Report

Abstract

The case describes the revision of an upper ankle prosthesis because of loosening. When ankle replacement is the first choice and actual bone quality does not allow a replacement of the prosthesis, arthrodesis is the only way of reducing pain and gaining stability. The amount of missing bone due to the removed prosthesis was severe. Shark Screws®, made of human allograft cortical bone, were used to fix an allograft femoral head and tibia as well as fibula and talus to each other for stabilization. This was performed without any autologous bone graft and without metal screws. The human matrix of the cortical allograft allows the creation of new vessels followed by osteoblastic activity and production of new bone. The revascularization of the allografts reduces the risk of infection and wound problems. Over time, the patient's bone metabolism allows the allografts to be remodeled into the patient's bone. The case reported here had severe multimorbidity. The loosening of the prosthesis mainly affected the ability to perform housework, mobility, enjoying leisure, and it had a great impact on the emotion and well-being of the patient. One year after surgery, the patient is very satisfied to be able to walk without pain and scratches for about 90 min.

Keywords: allograft; arthrodesis; case report; cortical bone screw (Shark Screw®); multimorbidity; upper ankle joint.

Conflict of interest statement

K.P. and E.P. are shareholders of Surgebright GmbH. The authors D.F., G.H.B. and M.C. declare that there are no conflicts of interest regarding the publication of this article.

Figures

Figure 1

X-rays: (a,b) before implantation of Salto-prosthesis, pre-OP 2005; X-rays show severe osteoarthrosis of the upper ankle with deformity of joint endplates, osteophyte formation and subchondral sclerosis, as well as periarticular calcifications; (c,d) post-surgical 2006, implanted Salto-prosthesis; with regular post-surgical status; (e,f) X-ray at a routine control performed in 2016 demonstrated beginning of bone resorption and lytic–cystic defects in the periphery of the tibial component while still regularly around the stem of the prosthesis and the talar component.

Figure 2

Pre-surgical images 2020: (a,b) X-rays, (c–e) CT scans of the patient; (a,b) large cysts are present in the tibia and in the talus, compared to the images from the year 2016 (Figure 1), a massive increase in bone resorption and cyst formation is seen around the tibial component under involvement of the stem of the prosthesis. Therefore, an increasing tilt of the joint surface of the tibial component can be seen as a sign of incipient dislocation; (c–e) CT scans confirm the X-ray findings with massive bone resorption, pathologic fracture of the lateral tibial cortical surface and instability of the tibial prosthesis component.

Figure 3

Surgical procedure: (a) Salto-prosthesis and necrotic talus; (b) after removal of the Salto-prosthesis bony defects and metal abrasion is visible; (c) bony defects on talus and tibia with metal abrasion.

Figure 4

Preparation of the fibula: (a,b) Shifting the split and pedicled fibula downward; (c) The fibula was fixed with a Shark Screw® diver (left screw) and with Shark Screws® cut (all 5 mm in diameter) toward the tibia.

Figure 5

Filling the bony defects: (a) Preparation of the tricortical chip, for supporting the distal cortical tibia. (b) Insertion of the tricortical chip under the distal lateral tibial area, as an additional load-bearing column. (c) One femoral head was shaped and was inserted into the tibia. (d) Drawing of the procedure performed: red: inserted allograft, violet: empty cavities, later filled with demineralized bone matrix, Sc: Shark Screw® cut, Sd: Shark Screw® diver.

Figure 6

Filling the defects: Filling the gap between fibula and tibia and smaller defects with demineralized bone matrix (DBM), inserted femoral head clearly visible.

Figure 7

Arthrodesis of the upper ankle joint: (a) Temporary placement of the drill wires and fixation of the fibula to the tibia; (b) Placement of a Shark Screw® diver from the tibia through the inserted femoral head for fixation of the talus.

Figure 8

X-rays just after surgery. Arthrodesis was performed with 6 Shark Screws® and a huge amount of allograft (femoral head and tricortical chip). (a) Ap-view; (b) lateral view.

Figure 9

(a,b) X-ray; (c–f) CT scans 12 weeks after surgery with a clearly visible formation of callosal bone being seen around the screws with the beginning of bony consolidation.

Figure 10

(a,b) X-rays; (c–f) CT scans 1 year after surgery. There is extensive callosal bone superstructing the distal fibular and tibia. It is clearly seen that, in particular, the situation within the distal tibia and the talus is in the status of good bony consolidation. No evidence of bone resorption or insufficiency of screws can be seen.

Figure 11

ROW-CT-3D-reconstruction 1 year after surgery. The arthrodesis of the fibula with the tibia is clearly visible.