SLR - November 2014 - Benjamin Saviet

Autologous Chondrocyte Implantation of the Ankle: 2- to 10-year Results

References: Kwak SK, Kern BS, Ferkel RD, Chan KW, Kasraeian , Applegate GR. Autologous Chondrocyte Implantation of the Ankle: 2- to 10-year results. Am J Sports Med. 2014 Sep; 42(9): 2156-64.

Scientific Literature Review

Reviewed By: Benjamin Saviet, DPM
Residency Program: Steward-St. Elizabeth’s Medical Center, Brighton, MA

Podiatric Relevance: Osteochondral lesions of the talus that are refractory to first line surgical therapy of arthroscopy, microfracture or drilling are difficult for both the patient and podiatric surgeon. Patients may continue to experience pain and podiatric surgeons have few options for further treatment. This study aimed to evaluate the long term results of one of the surgical procedures of choice for patients who have already failed initial surgical intervention: autologous chondrocyte implantation.

Methods: The study was a prospective cohort of 32 consecutive patients, 29 of whom were available for follow up, who had previously failed first line surgical therapy for osteochondral lesions of the talus. Patients were subsequently treated with implantation of autologous chondrocytes harvested arthroscopically from the intertrochanteric region of the knee. Procedures were performed by a single surgeon over an eight year period. Inclusion criteria were 15-50 years old, focal lesions >1cm2, persistent pain after previous surgery and with non-operative management, and MRI showing defect of cartilage and subchondral bone. Patients were evaluated using the AOFAS ankle-hindfoot scale, Tegner activity score, simplified symptomatology evaluation as well as return to sport and willingness to undergo procedure again. Second look arthroscopy was performed in 85% of patients and MRI reevaluation in 83 percentof patients. Patients were followed for an average of 70 months (24-129 months).

Results: In this cohort of patients, no intraoperative or post-op complications were experienced. The average AOFAS ankle hindfoot scores improved significantly from 50.1 pre-operatively to 85.9 at final follow up. Tegner scores, which measure participation in sports (average 6.0 for male, 5.6 for women), improved significantly from 1.6 to 4.3. No correlation was found between size of lesion repaired and AOFAS scores post-operatively. 93 percent of patients reported that they would undergo the procedure again. Of the 29 ankles pre-operatively reported as poor (n=26) or fair (n=3), nine were post-operatively rated excellent, 14 good and five fair, leaving only one patient with a poorly rated ankle post-operative. The nine patients with larger defects who underwent the "sandwich" procedure all reported good or excellent outcomes. Second look arthroscopic procedures in 25 patients showed no exposed bone in any of the ankles and 22 of the ankles were graded normal or nearly normal although 11 required debridement of hypertrophic periosteum. MRI re-evaluation post-operatively of 24 patients showed that all had good or moderate fill of prior lesions, but heterogenous results were noted for surface regularity and residual bone marrow edema

Conclusions: The authors conclude from their results that ACI is a good and predictable surgical procedure for patients that have failed prior surgical treatment of osteochondral lesions of the talus. They also conclude that the repair is durable by compiling results for an average of 102 months from their initial treatment group. The authors state that the use of knee chondrocytes as donor cells provide good outcomes with low donor site morbidity, but do not exclude the possibility of using ankle chondrocytes in the future as they may be more stress resistant. The authors also conclude that large defects are well treated with ACI and that size of initial defect may predispose patients to failure of initial surgical intervention.

This study shows that autologous chondrocyte implantation for osteochondral defects of the talus can be successful in eliminating pain and achieving positive short- and long-term outcomes. While many patients report good outcomes with initial therapy of marrow stimulation techniques like debridement, microfracture and drilling, this procedure adds to the podiatric surgeon's armamentarium for those lesions that remain painful after first line intervention. The procedure appears to do an exceptional job with large defects that are likely to fail first line surgical therapy and may be indicated as initial intervention for defects larger than 1.5cm2. A downside of this study was the numerous surgical procedures. Patients failed initial surgical intervention for their osteochondral lesion, underwent knee arthroscopy for chondrocyte harvest and had at least one more surgery for implantation of the harvested chondrocytes with many undergoing an arthroscopic procedure of the ankle months later for a total of four surgeries. In practice, the procedure could likely be streamlined to only two surgeries (chondrocyte harvest and ACI) if patients present with large lesions that would likely fail standard initial therapy. Other downsides of the study are lack of a control group that would have allowed for randomization and the small size of the study (n=32). From the podiatric perspective, harvesting cells from the knee necessitates collaboration with orthopedic surgeons.  In the future, harvesting chondrocytes from within the foot and ankle may provide an alternative to this if donor site morbidity can be kept low and quality of cells can be maintained.

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