A study recently published in the American Journal of Sports
Medicine highlighted previous knee surgery, bone marrow stimulation,
periosteum patch covered technique and female gender as significant predictors
of re-intervention after
autologous chondrocyte implantation for
cartilage defects of the knee.
The researchers examined eight other risk factors for re-intervention
after autologous chondrocyte implantation (ACI) in 413 patients at a 2-year to
11.8-year follow-up that did not show a statistically significant influence,
including body mass index, patient age, number of defects, defect size,
parallel treatment, legion origin and location, and smoking. A subset of 88
patients of the 413 patients (23.1%) underwent revision surgery.
“We identified various risk factors associated with an increased
risk for the need for re-intervention after ACI,” study investigator Pia
M. Jungmann, MD, from the Department of Orthopedics and Trauma Surgery directed
by Prof. Norbert P. Südkamp at Freiburg University Hospital in Germany,
told Orthopedics Today. “All these factors should be taken
into account when indicating ACI.”
Risk factors for ACI
In addition to analyzing each potential risk factor separately, the
researchers used logistic regression models and a Cox regression model for
survival analysis, including forward and backward regression, to strengthen
results and to exclude differences in follow-up.
“With all these statistical analyses, we actually found the same
result, which underlines the importance of this study because the same risk
factors were filtered and identified in each model,” Jungmann said.
A grade III ICRS full-thickness isolated cartilage defect of the
medial femoral condyle is pictured. Surgeons made an indication for ACI in this
This intraoperative image shows a patient treated with
autologous chondrocyte implantation for a full- thickness cartilage defect of
the medial femoral condyle.
Images: Niemeyer P
She added, “Risk for re-intervention is just one specific parameter
in a complex context and only one outcome parameter. Need for re-intervention
does not necessarily mean ‘treatment failure’ because these patients
can still have a good outcome after this re-intervention and profit from
Jungmann noted that the study builds on previous work conducted by head
author, Philipp Niemeyer, MD, PhD. In one such study, Niemeyer and colleagues
analyzed characteristic complications after ACI. In a further study, they
discovered that ACI after failed microfracture was significantly associated
with inferior outcomes. Additional studies concluded that cell quality during
transplantation had an effect on the clinical outcome of ACI.
“We restricted the observation plan to 5 years to eliminate
differences in the operation technique mainly, not only in the survival
analysis but also in the other, statistical analyses. This would need to be
extended in future studies,” Jungmann said, adding that the minimum 2-year
follow-up study showed a mean time to failure of 1.8 years. – by Jeff
- Jungmann PM, Salzmann GM, Schmal HS, et al. Autologous chondrocyte
implantation for treatment of cartilage defects of the knee: What predicts the
need for reintervention? Am J Sports Med. 2012; 40:1:58-67.
- Niemeyer P, Pestka JM, Kreuz PC, et al. Characteristic
complications after autologous chondrocyte implantation for cartilage defects
of the knee joint. Am J Sports Med. 2008;36:2091-2099.
- Niemeyer P, Pestka JM, Salzmann GM, et al. Influence of cell
quality on clinical outcome after autologous chondrocyte implantation. Am
J Sports Med. 2011. Published online Dec 14, 2011.
- Pestka JM, Bode G, Salzmann G, et al. Clinical outcome of
autologous chondrocyte implantation for failed microfracture treatment of
full-thickness cartilage defects of the knee joint. Am J Sports
Med. 2011. Published online Nov 5, 2011.
- Pia M. Jungmann, MD, can be reached at the Department of Radiology
and Biomedical Imaging, Musculoskeletal and Quantitative Imaging Research,
University of California San Francisco, 185 Berry St., Suite 350, San
Francisco, CA 94107; email: email@example.com.
- Disclosure: Niemeyer received grants for limited educational
purposes from TiGenix and Stryker.