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Patients returned to functional level after second-generation patellofemoral joint ACI
Identifying the relative contributions of ACI in the future may be valuable to treatment.
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Investigators reported good success at about 2-year follow-up when they treated cartilage lesions in the patellofemoral joint sized 502 mm2 with a predominantly second-generation cartilage repair technique. Most of the lesions were on the patella in the 75 knees treated in a military population of 74 active, young high-demand patients.
In a presentation at the American Orthopaedic Society for Sports Medicine Annual Meeting, Nicholas J. Zarkadis, DO, CPT, MC, said, “We have identified the potential predictors of failure for [autologous chondrocyte implantation] ACI in the patellofemoral joint. We demonstrated that ACI can be performed in the patellofemoral joint and can return approximately 75% of our active population to their preoperative level of function and that, regardless of outcome, the patients can expect improvement in their knee pain.”
In an interview with Orthopedics Today, Brian R. Waterman, MD, a study investigator and senior author, noted that female patients, tobacco use, a periosteal patch and age younger than 30 years at the time of ACI were factors associated with failure.
ACI yielded good results
The retrospective study included U.S. military and Tricare beneficiaries who underwent ACI for Outerbridge grade 3 or 4 patellofemoral chondral defects. The procedures were performed at two military medical centers between 2007 and 2014. The surgeries involved autologous, cultured chondrocytes (Vericel Corp.) and type I/III collagen bilayer membrane or periosteal patch.
Investigators performed a univariate analysis to determine whether there were any significant independent predictors of surgical failure. Surgical failure was defined as a revision chondral procedure or later conversion to patellofemoral knee arthroplasty.
Source: Brian R. Waterman, MD
The patients had a median age of about 34 years and some of them used tobacco at the time of surgery.
Among the 16 failures in the series, four patients (5.3%) required secondary surgery, including one revision and three cases of patellofemoral arthroplasty. At an average of 1.9 years postoperatively, 14 patients underwent medical discharge due to persistent knee pain, Zarkadis said at the meeting.
According to results, investigators found no surgical or demographic factors that were significantly associated with an adverse clinical outcome.
“However, just because somebody experienced a ‘clinical failure’ with inability to return to military duty, this did not mean they did not have statistically significant improvements in their pain,” Waterman said.
ACI contributions
The retrospective study design and short-term outcomes were limitations of the study, as well as “limited patient-reported outcome measures and lack of a control group,” Zarkadis said in his presentation.
According to Waterman, it would be valuable to eventually identify the relative contributions of the tibial tubercle osteotomy alone vs. combined chondral restoration with ACI or with matrix-assisted ACI (MACI).
“It would also be interesting to look at how the newer, third-generation MACI technique bears out at short to longer-term follow-up and whether it surpasses the results documented with second-generation ACI for patellofemoral chondral defects,” Waterman said. – by Susan M. Rapp and Casey Tingle
Editor’s note: On Jan. 3, the original order of appearance of Figures 1 and 2 in the article was changed to their currently displayed order.
- Reference:
- Zarkadis NJ, et al. Paper #122. Presented at: American Orthopaedic Society for Sports Medicine Annual Meeting; July 20-23, 2017; Toronto.
- For more information:
- Nicholas J. Zarkadis, DO, CPT, MC, can be reached at William Beaumont Army Medical Center, 5005 N. Piedras St., El Paso, TX 79920; email: nickzarkadis@gmail.com.
- Brian R. Waterman, MD, can be reached at Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157; email: brian.r.waterman@gmail.com.
Disclosures: Waterman reports he is a trainer and speaker for Vericel. Zarkadis reports no relevant financial disclosures.