Autologous Chondrocyte Implantation for Treatment of Cartilage Defects of the Knee: What Predicts the Need for Reintervention?

Jungmann PM, Slazmann GM, Scmal H, Pestka JM, Sudkamp NP, & Niemeyer P. American Journal of Sports Medicine. 2012;40(1): 58-67. 

Autologous chondrocyte implantation (ACI) aims to repair a chondral defect within the knee by harvesting and growing the patient’s cartilage that is then placed in the defect.  The procedure has shown relatively favorable outcomes; however, it still carries a failure rate ranging from 10 to 20 %.  Failure of ACI results in a need for another surgery.  The purpose of this study was to identify risk factors associated with the need for a second (corrective) surgery after ACI. This study identified 88 patients (21.3%) from a larger cohort (n = 413) who needed a second knee surgery within 5 years after various ACI surgical procedures (completed by multiple surgeons).  All 88 patients had at least 2 years follow-up (maximum = 11.8 years). Diagnoses were made during arthroscopic revision surgery, and analyses were made on 12 prognostic (pre-operative) factors (e.g., body mass index [BMI], gender, age).  The authors identified four factors as potential risk factors for failure (needing a second/corrective surgery).  Patients who were female, had more than one previous surgery on the same joint for any condition, had previous bone marrow stimulation (e.g., microfracture), or had ACI surgical technique involving a periosteal patch were identified as having an increased incidence of reintervention.  Surgeon, BMI, and age were not associated with an increased risk of requiring a second surgery.

Clinically, we need to be aware of these potential risk factors as patients are opting for ACI surgery.  Awareness that females are more at risk for ACI failure is important; however, there is not much that we can do clinically regarding this beyond education or suggesting alternative treatments.  More interestingly, in the athletic population, ACI is sometimes viewed as a surgery to complete once they are done competing.  It would be interesting to see physical activity information, as this was not reported for this cohort of patients.  However, some athletes are counseled into receiving microfracture (drilling of subchondral bone) surgery first, and then if this fails to try ACI.  This study indicates that this recommendation should be reconsidered and that it, in fact, may increase the likelihood of ACI surgeries failing.  For ACI to be successful, it may be more appropriate if we viewed ACI as a primary option, as opposed to a “back-up plan.”  More than one previous surgery was also identified as a potential factor that increases the likelihood of ACI failure.  The types of previous surgeries are not indicated, but as sports medicine professionals, we should be investigating how to mitigate this seemingly unmodifiable risk factor.  Lastly, as the ACI surgical techniques are evolving it seems that the type of ACI surgery may have an effect on the outcome.  This study looked at three different ACI techniques (i.e., periosteal patch-covered ACI, Chondro-Gide-covered ACI, and matrix associated Bio-Seed-C), and identified that the periosteal patch-covered technique is associated higher incidence of reintervention.  As patients are considering which surgeon or technique to have, we, as clinicians, can help to inform the decisions that they are making.  Interestingly enough, the follow-up time identified in this study to define a successful ACI intervention was five years.  Following these patients for a longer period of time could prove advantageous in identifying the need for any reintervention, and their progression towards osteoarthritis.  Furthermore, this cohort only included patients who did not have concomitant ligament/meniscal surgeries.  It would be interesting to see the outcomes of this surgery in other cohorts to determine whether or not this is a viable option in these cohorts as well.  What are your thoughts on when ACI should be attempted?  Has anyone had an athlete or patient who has undergone any ACI technique?

Written by: Nicole Cattano
Reviewed by: Jeffrey Driban

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Matrix-induced Autologous Chondrocyte Implantation (MACI) in the Knee

Jungmann PM, Salzmann GM, Schmal H, Pestka JM, Südkamp NP, & Niemeyer P (2012). Autologous chondrocyte implantation for treatment of cartilage defects of the knee: what predicts the need for reintervention? The American Journal of Sports Medicine, 40 (1), 58-67 PMID: 21969180