Microstructural scaffold (patch) insertion without autologous cell implantation for repairing symptomatic chondral knee defects

5.1 Haematoma, after the autologous matrix-induced chondrogenesis (AMIC) procedure, developed in 1 patient in a case series of 38 patients (40 knees) with full-thickness chondral and osteochondral defects of the femoral condyles and patella. The haematoma was excavated. Bleeding and swelling of the knee after surgery was reported in 12% (6/49) of patients in a case series of 49 patients, all of which resolved spontaneously within 1 week. Swelling, which resolved in a few days, was reported in 22% (17/79) of patients in a case series of 82 patients with chondral or osteochondral knee lesions.

5.2 Muscle vein thrombosis was reported in 1 patient in a case series of 27 patients with 32 chondral lesions treated with AMIC. This complication resolved after treatment.

5.3 Effusion 'after tumbling' was reported in 1 patient in the case series of 27 patients. This complication resolved after treatment.

5.4 Knee stiffness was reported in 23% (9/40) patients in the case series of 38 patients (40 knees) after the procedure. This was reported in patients in the chondral patella group. Patients regained full range of motion after mobilisation under anaesthesia.

5.5 Revision surgery, because of pain and limited function of the knee, was done in 10% (5/49) of patients in a case series of 49 patients with large osteochondral knee lesions treated with a biomimetic osteochondral scaffold. In 2 patients with osteonecrosis of the medial femoral condyle, unicompartmental knee replacement was done in 1 patient and a valgus high tibial osteotomy was done in the other patient. In 2 patients with osteochondritis dissecans, autologous osteochondral transplantation revision surgery was done in 1 patient and osteochondral allograft transplantation and varus femoral osteotomy was done in the other patient. The fifth patient, who was lost to follow-up, had treatment at another centre. Revision surgery was done in 8% (2/27) of patients due to symptoms of grinding, catching, pain or swelling after the procedure in the case series of 27 patients. Clinical improvement was not seen in these patients.

5.6 In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed the following anecdotal adverse events: delamination of repair tissue and the need for surgical removal of this tissue, and hypertrophy. They considered that allergic reaction to materials used in preparation or preservation of scaffold was a theoretical adverse event.