Topic 8 · Treatment options
Subchondralplasty (Bone Substitute Injection)
Fills the cyst; does not resurface the cartilage above it. Raised and then de-emphasised by Dr. Choung.
What It Is
→ Bone under cartilage has a hole (cyst) filled with fluid. Subchondralplasty injects bone cement-like paste through a needle to fill it. The paste hardens and becomes part of your bone. Like filling a pothole in a road.
Minimally invasive technique injecting calcium phosphite paste into subchondral cysts. The paste crystallizes like cancellous bone to fill the defect [48].
Reported Outcomes
- 6-month CT: >50% of cyst replaced by bone substitute integrated with trabecular network [49]
- 1-year follow-up: Pain-free walking, preserved ROM [49]
- Patients report little to no post-op pain, same-day discharge [50]
2024-2025 Subchondralplasty Updates
Recent studies have expanded understanding of this technique [85]:
- 2024 systematic review: 78% patient satisfaction at 2-year follow-up
- Best outcomes in isolated bone marrow edema without full-thickness cartilage loss
- May be combined with microfracture or scaffolds for comprehensive treatment
Calcium Phosphate vs Other Substitutes (2024)
A 2024 comparative study examined different bone substitutes [50]:
- Calcium phosphate (AccuFill): Most commonly used, good integration
- Bioresorbable materials show promise but lack long-term data
- Injectable DBM (demineralized bone matrix) alternatives emerging
Complications
- Traditional bone-grafting has 27-63% cyst recurrence rate [48]
- Reported complications: AVN of talus, osteomyelitis (rare) [51]
- Overfilling can cause pain; intra-articular extravasation is a risk [49]
Retrograde Drilling + Bone Graft
Alternative approach: retrograde drilling has ~90% success rate for intact cartilage lesions [52]. However, failure rates can reach 20% due to inaccurate targeting [53].
Navigation-Assisted Drilling (2024-2025)
Newer navigation technologies improve accuracy [52]:
- 3D CT-based navigation: 95% accuracy in cyst targeting
- Fluoroscopic guidance: Traditional but less precise
- Patient-specific instruments emerging for complex cases
For Raymond: Dr. Choung noted the cysts are small and mostly inflammatory, making subchondralplasty not currently indicated.