As per current standard of care for focal articular cartilage lesions of the acetabulum, the unstable cartilage will be debrided and removed from the subchondral bone using a mechanical shaver until a stable margin is obtained. A ring curette will be used to remove the calcified cartilage layer and create a border of healthy cartilage tissue that can support the marrow clot. Through the mid-anterior portal, specialized 90˚ awls will then be placed with the tip perpendicular to the subchondral bone of the acetabulum, and a mallet will be used to penetrate the subchondral bone with perforations 3 mm deep to access the bone marrow elements. This is done until the defect is homogeneously covered with micro-perforations 2-3 mm apart.

Those allocated to the AMIC treatment group will also receive microfracture. Once the walls of the debrided lesion are confirmed to be stable with a probe, the exact size of the defect will be measured for templating of the scaffold. The dry Chondro-Gide® matrix will be prepared by cutting it to 10% smaller than the focal defect (as it increases in size about 10% after moistening). Once the cartilage lesion is dried manually, the implant will then be secured to the defect in a press-fit fashion to the surrounding cartilage. Manual pressure is then applied to secure the implant into the defect and the hip is released from traction and rotated to facilitate further fixation of the graft. Traction is then applied to arthroscopically confirm position and fixation of the implant.

AMIC is a novel approach in which the microfracture technique has been enhanced by the use of a type I/III collagen matrix (Chondro-Gide®; Geistlich Pharma AG, Wolhusen, Switzerland). In this single-step procedure, the matrix is placed over the defect to stabilize the fragile blood clot that arises from microfracture and to provide infrastructure for repair tissue formation. Essentially, the matrix covers the defect and serves as a protective shield that contains the cells and minimizes the impact of shear forces when moving the hip on the delicate blood clot. At the same time, it functions as the roof of a biological chamber that forms over the defect. The biocompatible collagen material provides an environment for cell growth and is replaced by native tissue over time.

The iHOT-33 is designed to measure hip-specific health-related quality of life changes after treatment of active young patients with hip disorders. The total score is calculated as a simple mean of the responses ranging from 0 to 100, with 100 representing the best possible quality-of-life score.

To measure hip pain. The total score is calculated as a single response ranging from 0 to 100, with 100 representing the worst possible pain.