Single-Stage Autologous Chondrocyte Co-Implantation on a Hyaluronan Scaffold for the Treatment of Knee Cartilage Lesions: A Case Series of 16 Patients with Clinical Outcomes up to Five Years

Background The isolation of autologous primary articular chondrocytes in the operating room and their direct, single-stage, reimplantation for the treatment of knee-cartilage lesions is still a new concept. Existing single-stage autologous chondrocyte implantation (ACI) variants have used either an osteochondrally placed scaffold or allogeneic cells to co-implant with the chondrocytes. There are no reports yet on clinical outcomes of a single-stage autologous-chondrocyte co-implantation strategy using autologous bone-marrow cells and a chondrally placed scaffold. We hypothesized that such a strategy would be safe and result in improved patient-reported outcomes. Our purpose was to describe clinical outcomes and re-interventions in the five years following the surgery. Methods A prospective case series was initiated including 16 patients (4 female, 12 male) suffering from single or multiple, focal, partial- thickness or full-thickness knee cartilage lesions that resulted from trauma or overuse. Mean age at baseline was 36.8 (± 11.5) years. Mean total lesion size was 4.5 (± 2.3) cm2. During the surgery, articular chondrocytes were isolated from cartilage and mononuclear bone-marrow cells were isolated from marrow aspirate. The cells were washed, counted, mixed, and then seeded onto a hyaluronan-based scaffold that was placed in the lesion before cell seeding. A specific physical therapy schedule was adhered to. Patients were followed-up for five years and filled in KOOS and IKDC Subjective questionnaires at baseline and at 3, 6, 12, 24, 36, 48, and 60 months post surgery. One patient was treated for both knees and reported different follow-up scores for the left and right knee. Results The patient-reported outcomes, in general, improved over the first three years following surgery and then tended to decline very slightly up to the five-year time point. Clinically and statistically significant improvements over baseline were reported for KOOS Pain at 3 and 4 years post surgery, for KOOS Other Symptoms and Activities of Daily Living at 1 year and onward, for KOOS Sport & Recreation and Quality of Life at 3 years and onward, and for the IKDC Subjective at 1 year and then again at 3 years and onward. Re-interventions were done for two patients: one received intraarticular injections with MSCs (8 months postoperatively), another was given a knee washout for septic arthritis while a meniscus implant was removed (3 weeks postoperatively). Patient satisfaction at final follow-up was predominantly good. The intraoperative cell-isolation time was significant, roughly 1½ hours, but was frequently used for concurrent interventions. The amount of intraoperatively obtained articular chondrocytes was ±0.9 million per case. Conclusion Co-implantation of intraoperatively isolated articular chondrocytes and mononuclear bone-marrow cells on a hyaluronan scaffold is a safe and efficacious strategy in the treatment of focal symptomatic knee-cartilage lesions. Clinical Relevance The technique studied is a single-stage variant of autologous chondrocyte implantation (ACI). The chondrocytes and co-implanted bone-marrow cells are isolated, washed, and counted, which allows for a controlled and well-documented description of the biologicals of the treatment.