Surgical technique of an innovative patient-specific metal implant for talar osteochondral lesions

Abstract

Purpose: Treatment strategies for osteochondral defects (OCDs) of the ankle have substantially increased over the last decade. The development of a small metallic implant to fill the defect has led to the second-generation patient-specific metal implant (Episealer Talus® Implant) designed based on computed tomography and magnetic resonance imaging images.

Methods: There is a pool of patients falling into the so-called 'treatment gap', a grey zone composed of active patients with symptomatic OCDs in the context of an otherwise healthy joint, or patients with a failed primary treatment. To minimize the risk of perioperative complications, there are a series of tips and tricks that can be considered.

Results: Correct execution of the operative approach, proper positioning of the guides, posterior capsule and deep deltoid ligament release and the use of Hintermann spreader allow a perfect visualization of the OCDs minimizing the risk of iatrogenic lesions. Correct execution of the medial malleolus osteotomy, release of soft tissue, proper triplanar alignment of the custom-made guide, its strong stabilization during the reaming and the use of vigorous washes minimizes the potential damage on healthy cartilage. Correct sinking of the implant is crucial; the goal is to place the Episealer Talus at least 0.5 mm below the cartilage surface. Filling a large subchondral cyst with the cancellous bone can be useful to provide better stability of the implant.

Conclusion: Episealer Talus for talar OCDs possibly represents an additional tool for surgeons and patients. It is important to avoid mistakes during implant placement.

Levels of evidence: Level V, expert opinion.

Keywords: ankle; custom‐made implant; osteochondral lesions.

Figure 1

The Damage Marking Report based on computed tomography/magnetic resonance imaging scans (above) and the final design of the Damage Marking Report (below).

Figure 2

Custom‐made surgical tools set and definitive implant.

Figure 3

Ankle medial approach. (a) Capsulotomy of the ankle and positioning of a Hohmann retractor; (b) Incision of retinaculum flexor to expose tibialis posterior tendon; (c) Positioning of the Hohmann retractor to protect the tibialis posterior tendon and positioning of the Medial Malleolus Osteotomy Guide.

Figure 4

Checking guide (Osteotomy Depth Metre) for the right length of the saw.

Figure 5

Medial exposure of the talar dome. (a) Malleolar osteotomy is initiated and (b) Subsequently terminated with an osteotome; (c) Overturning of the medial malleolus; (d) Increasing the articular space between tibia and talus using a Hintermann distraction forceps.

Figure 6

Identification of the osteochondral lesion. (a) Positioning of the Epiguide on the medial talar dome edge; (b) Insertion of the Pin Socket inside the Epiguide.

Figure 7

Creation of the implant housing. (a) Reaming with the Epidrill; (b) Final drill using the Adjustment Socket, for an accurate submillimetric adjustment of the depth; (c) Check of the implant recession by using the Epidummy, an exact replica of the shape of the final implant.

Figure 8

Definitive implant housing. Note the pen marks for the direction of rotation.

Figure 9

Placing the Episealer talus into the drilled hole.

Figure 10

Anatomical reduction of the medial malleolus and osteosynthesis with two compression screws.

Figure 11

Postoperative x‐rays for medial osteochondral defect.

Figure 12

Ankle lateral approach. (a) Lateral capsulotomy of the ankle is performed by removing a part of the joint capsule; (b) Removing the anterior talofibular ligament + calcaneofibular ligament as ‘one flap of tissue’ and anterior dislocation of the talus with a Hintermann spreader.

Figure 13

Implant of the temporary (on the left) and final (on the right) component.

Figure 14

External capsule‐ligamentous reconstruction with a nonanatomical technique using Bunnell sutures.

Figure 15

Postoperative x‐rays for lateral osteochondral defect.