Autologous Chondrocyte Implantation (ACI/MACI)

Added August 6, 2026 — the longest MACI-in-the-talus follow-up there is, and it was written by the two surgeons this site tells him to call

→ This page was the thinnest on the site, and it was missing the one paper that connects the treatment to the specific people who might deliver it. Found by enumerating every cartilage publication by the UC Davis surgeons rather than by searching this week's literature.

Kreulen C, Giza E, Walton J, Sullivan M — “Seven-Year Follow-up of Matrix-Induced Autologous Implantation in Talus Articular Defects”, Foot & Ankle Specialist 2018 [382]. Dr. Kreulen and Dr. Giza are the UC Davis foot-and-ankle surgeons already named on the Next Steps tab — Giza is the MASCOT principal investigator — and this site had never cited the paper that most directly qualifies them for the recommendation.

• Prospective series of 10 patients who “had failed previous arthroscopic treatment”; 9 available at seven years
• AOFAS 61.8 → 78.3 (P = .05), with significant SF-36 improvements in physical functioning, bodily pain and social functioning
• Authors' conclusion: MACI “provides a stable midterm chondral replacement strategy for osteochondral lesions that fail initial microfracture”
• The limits matter as much as the result: n=9, single arm, no control group, Level IV. And the “failed previous treatment” here means failed arthroscopic treatment — microfracture and debridement — not a failed structural allograft. It is a closer analogue than most of the MACI literature, which is primary-lesion work, but it is not his situation

→ Why it is worth knowing before the call: it means the surgeon running the trial has personally followed a revision MACI cohort for seven years. That is a far better conversation opener than the trial protocol, and it is a fair question to ask him — how did those nine patients do, and how are they doing now?

20-Year Follow-Up Data (2024)

→ ACI: Two surgeries. First, surgeon takes healthy cartilage cells and a lab grows millions more (4-6 weeks). Second surgery implants them. MACI grows cells on a scaffold membrane for easier implantation.

A landmark 2024 study evaluated first-generation ACI with minimum 20-year follow-up [90]:

• AOFAS improved from 40.4 to 82.7 at final follow-up (p<0.0005)
• Pain NRS improved from 7.8 to 4.8 (p<0.0005)
• All patients preserved their ankle joints without needing major revision surgery
• Some decline in outcomes and activity restrictions reported over time

MACI Systematic Review (2024)

A 2024 systematic review of 166 MACI patients [91]:

Indications

• MACI recommended for defects >2 cm² [24]
• Requires two surgeries (biopsy + implantation)
• Higher cost due to cell culture process
• Best for larger lesions where BMS/scaffolds are insufficient

Revision Context (2024)

The 2024 revision systematic review found ACI had the best pooled PRO performance in non-primary OLTs, but the dataset was tiny (only 7 ankles) [148]. DGOU 2024 also notes there is no evidence of added benefit of ACI over acellular scaffolds in the talus [128].

For Raymond: ACI/MACI is more compelling when the problem is primarily cartilaginous. A bone-supported graft wearing out points more toward osteochondral or osteoperiosteal reconstruction.

Added August 25, 2026 — how much to trust the failure rates on this page depends on who was counting

→ A new review compared MACI studies that planned their follow-up in advance (prospective) against ones that looked back at old charts (retrospective). The carefully-watched patients showed a 4.3% graft failure rate; the looked-back-at charts showed 0.06%. Same procedure — a seventy-fold difference, produced entirely by how the counting was done.

A USC / Harbor-UCLA systematic review of 28 MACI studies (1,484 knees) split the literature by design and found graft failure reported at 4.30% in prospective studies versus 0.06% in retrospective ones (P=.0043), while hypertrophy, reoperation and complication rates did not differ by design [439]. All knees — but this page’s numbers are the reason it is carried. The talar MACI evidence here is small case series: the 10-patient Kreulen/Giza seven-year cohort [382] is prospective, which by this review’s logic makes its honesty about outcomes more, not less, credible; the older talus series behind the 78–95 AOFAS range and “89% success” figures above are mostly retrospective — exactly the design this review finds essentially never reports a graft failure. The practical reading: treat retrospective success rates on this page as ceilings, and give prospective series’ less flattering numbers the greater weight. It also sharpens the question this page already suggests asking Dr. Giza about his nine patients — not just “how did they do” but “how many grafts failed, and how was failure defined.”