Novel Surgical Approach for Large Intraosseous Subchondral Cysts of Talus: A Case Report and Technical Innovation

Abstract

Large subchondral bone cysts in the medial talar body and dome are common and can cause persistent pain and swelling during axial loading. Open debridement and bone grafting are often necessary to treat these lesions but can require extensive soft-tissue dissection or malleolar osteotomies. A 40-year-old woman presented with ankle pain and swelling for 1 year, worsening with activity and no history of trauma. X-rays showed a cystic lesion in the medial talar dome with no joint line disruption. CT confirmed the cystic lesion without bone collapse or expansion. An anterior approach to the ankle joint was extended to access the talar neck. A window was created in the talar neck to debride and curette the medial talar dome, and the void was filled with allograft. The patient was non-weight-bearing for 6 weeks, followed by gradual weight-bearing and ankle range of motion exercises starting on postoperative day 1. The patient returned to her pre-injury status within 3 months and was asymptomatic at the 6-year follow-up, with good bone graft integration and no symptoms. This technical note presents a novel approach to lesions of the medial talar body and dome through the talar neck, avoiding the need for malleolar osteotomy or disruption to the tibiotalar joint, and resulting in good functional outcomes.

Keywords: bone grafting; intraosseous lesion; novel surgical approach; subchondral cyst; talar dome.

Figure 1. Preoperative Imaging

Figure 1A shows preoperative x-ray showing radiolucent regions in the subchondral area of the medial talar dome and body of the talus, with no joint line disruption. Figure 2B (sagittal) and 2C (coronal) CT scan cuts showing radiolucent multiloculated cyst in the medial talar dome and body, without any signs of bone collapse or expansion.

Figure 2. Sequential Surgical Steps

Figure 2A shows incision from the medial malleolus to the talonavicular joint to approach medial talar neck. Figure 2B shows a final exposure of talar neck. Figure 2C shows identification of medial talar neck. Figure 2D shows confirmation of talar neck under fluoroscopy.

Figure 3. Sequential Surgical Steps

Figure 3A shows a carefully made window in the medial talar neck. Figure 3B shows an angled curette for the thorough removal of the cyst. Figure 3C shows the allograft used. Figure 3D shows the complete packing of the cyst with bone graft. Figure 3E shows postoperative fluoroscopic image showing the cyst completely filled with bone graft.

Figure 4. Sequential Radiographs

Serial yearly follow-up x-rays showing good integration of bone graft with some signs of degenerative changes and no recurrence. Figure 4A - 2017, Figure 4B - 2018, Figure 4C - 2019, Figure 4D - 2021, Figure 4E - 2022.