Saris, Daniël B.F.

Background: As the number of cartilage restoration procedures is increasing, so is the number of revision procedures. However, there remains limited information on the reasons for failure of primary cartilage restoration procedures. Purpose: To determine the common modes of failure in primary cartilage restoration procedures to improve surgical decision making and patient outcomes. Study Design: Case series; Level of evidence, 4. Methods: Patients who presented for revision after failed cartilage repair surgery were evaluated for factors contributing to failure of the primary procedure. All revision cases performed by a single surgeon at a tertiary center for failed cartilage restoration over a 6-year time frame were identified. In all cases, the medical records, preoperative radiographs, and magnetic resonance imaging scans were reviewed by 2 experienced cartilage surgeons. The cause for failure was categorized as malalignment, meniscal deficiency, graft or biologic failure, or instability. Univariate and descriptive statistics regarding patient demographics, index procedure, lesion location and size, and mechanism of failure were analyzed. Results: A total of 59 cases in 53 patients (32 male, 21 female) met the inclusion criteria. The mean patient age at the time of revision was 27.6 years, and the mean body mass index was 28.4 kg/m 2 . Failed index surgical procedures included 35 microfractures (59%), 12 osteochondral allograft transplantations (20%), 10 osteochondral autograft transfers (17%), 2 nonviable osteochondral allografts (3%), and 2 particulated juvenile chondral allografts (3%). The mean lesion size was 4.4 cm 2 . Reasons for failure included 33 cases with untreated malalignment (56%), 16 with graft failure (27%), 11 with untreated meniscal deficiency (19%), and 3 with untreated instability (5%); 4 cases demonstrated multiple reasons for failure. Conclusion: The most commonly recognized reason for failure was untreated malalignment. While biologic and graft failures will occur, the majority of failures were attributed to untreated background factors such as malalignment, meniscal deficiency, and instability. The stepwise approach of considering and addressing alignment, meniscal volume, and stability remains essential in cartilage restoration surgery.

Background: Matrix-based cell therapy improves surgical handling, increases patient comfort, and allows for expanded indications with better reliability within the knee joint. Five-year efficacy and safety of autologous cultured chondrocytes on porcine collagen membrane (MACI) versus microfracture for treating cartilage defects have not yet been reported from any randomized controlled clinical trial. Purpose: To examine the clinical efficacy and safety results at 5 years after treatment with MACI and compare these with the efficacy and safety of microfracture treatment for symptomatic cartilage defects of the knee. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: This article describes the 5-year follow-up of the SUMMIT (Superiority of MACI Implant Versus Microfracture Treatment) clinical trial conducted at 14 study sites in Europe. All 144 patients who participated in SUMMIT were eligible to enroll; analyses of the 5-year data were performed with data from patients who signed informed consent and continued in the Extension study. Results: Of the 144 patients randomized in the SUMMIT trial, 128 signed informed consent and continued observation in the Extension study: 65 MACI (90.3%) and 63 microfracture (87.5%). The improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Pain and Function domains previously described were maintained over the 5-year follow-up. Five years after treatment, the improvement in MACI over microfracture in the co-primary endpoint of KOOS pain and function was maintained and was clinically and statistically significant ( P = .022). Improvements in activities of daily living remained statistically significantly better ( P = .007) in MACI patients, with quality of life and other symptoms remaining numerically higher in MACI patients but losing statistical significance relative to the results of the SUMMIT 2-year analysis. Magnetic resonance imaging (MRI) evaluation of structural repair was performed in 120 patients at year 5. As in the 2-year SUMMIT (MACI00206) results, the MRI evaluation showed improvement in defect filling for both treatments; however, no statistically significant differences were noted between treatment groups. Conclusion: Symptomatic cartilage knee defects 3 cm 2 or larger treated with MACI were clinically and statistically significantly improved at 5 years compared with microfracture treatment. No remarkable adverse events or safety issues were noted in this heterogeneous patient population.

Abstract Isolated cartilage defects can lead to significant pain and disability, prompting the development of a number of options for restorative treatment. Each method has advantages and limitations, and no single technique has gained widespread use. We present a technique for implantation of a cryopreserved osteochondral allograft (Cartiform) for the treatment of full‐thickness cartilage defects. Cartiform is a cryopreserved osteochondral allograft composed of chondrocytes, chondrogenic growth factors, and extracellular matrix proteins. This implant allows for regenerative treatment of full‐thickness cartilage lesions in a single surgical procedure. Technique Video video See video under supplementary data.

AbstractMSCs are known as multipotent mesenchymal stem cells that have been found capable of differentiating into various lineages including cartilage. However, recent studies suggest MSCs are pericytes that stimulate tissue repair through trophic signaling. Aimed at articular cartilage repair in a one-stage cell transplantation, this study provides first clinical evidence that MSCs stimulate autologous cartilage repair in the knee without engrafting in the host tissue. A phase I (first-in-man) clinical trial studied the one-stage application of allogeneic MSCs mixed with 10% or 20% recycled defect derived autologous chondrons for the treatment of cartilage defects in 35 patients. No treatment-related serious adverse events were found and statistically significant improvement in clinical outcome shown. Magnetic resonance imaging and second-look arthroscopies showed consistent newly formed cartilage tissue. A biopsy taken from the center of the repair tissue was found to have hyaline-like features with a high concentration of proteoglycans and type II collagen. DNA short tandem repeat analysis delivered unique proof that the regenerated tissue contained patient-DNA only. These findings support the hypothesis that allogeneic MSCs stimulate a regenerative host response. This first-in-man trial supports a paradigm shift in which MSCs are applied as augmentations or “signaling cells” rather than differentiating stem cells and opens doors for other applications.