The typical matrix-assisted microfracturing treatment is depicted below for the knee.*
1. Initial Arthroscopy
Typically, an initial arthroscopic examination is carried out to assess the extent of joint damage. Size and grade of the cartilage defect can be diagnosed and necessary accompanying interventions, such as the treatment of meniscal damage, can be performed.
For defects smaller than 2 cm², debridement of the cartilage defect and a standard Micro- or Nanofracturing is usually a sufficient treatment. In case a defect size larger than 2 cm² is observed during the arthroscopy, it is recommended to cover the defect area with a Cartimaix membrane after the subchondral perforation and to prevent the loss of released bone marrow cells into the joint space.
2. Preparing the Defect
Depending on the cartilage defect localization the knee joint is typically opened by a small incision (miniarthrotomy). The defect is circumscribed with a scalpel to expose healthy cartilage leaving a vertical cartilage wall. Loose and damaged cartilage is debrided down to the subchondral bone plate using a ring curette or osteotome.
3. Outline imprinting with the Template
To facilitate exact cutting of the Cartimaix membrane to the shape of the prepared defect site, each Cartimaix package contains a sterile aluminium foil (“Template”). The outline of the prepared defect can be imprinted by pressing the Template with the blank side into the lesion until the imprint mirrors the defect. According to the shaped contour the Template is cut to size. Finally, the size of the cut-to-size Template can be verified by fitting it into the defect.
4. Preparation and cut-to-size of Cartimaix
The Cartimaix membrane is removed from the sterile packaging and can be cut to size either dry or rehydrated. If the dry membrane is cut to size, a slight increase of the membrane surface after rehydration should be considered. The cut-to-size Template is now placed on the Cartimaix membrane, the unprinted side facing the smooth, dense side of Cartimaix. The membrane is cut out along the Template exactly to the contour of the prepared cartilage defect.
After removal of the Template, the cut-to-size Cartimaix membrane can be fitted into the defect area. Due to the excellent handling characteristics of Cartimaix in rehydrated state a correction of the pre-cut after fitting is easily possible.
To ensure a secure fixation of the membrane, Cartimaix should be placed within the healthy, vertical cartilage walls and should not overlap them.
Please pay attention to Cartimaix orientation during handling.
5. Establishing access to the subchondral bone marrow
After debridement and preparation of Cartimaix access to the subchondral bone marrow will be established by perforating the subchondral bone plate with a sharp awl or pick.
Recent studies show improved results for thinner and deeper perforations.20-24 Innovative instruments such as the NanoFX® system generate particularly small perforations of a defined depth to access the subchondral bone marrow. In order to maintain the mechanical stability of the remaining bone bridges, the minimum distance between perforations should not be smaller than 3-5 mm.
Finally, fibrin glue is applied to the perforated area to prepare the wound bed for the subsequent fixation of the membrane within the defect.
6. Positioning of Cartimaix
The Cartimaix membrane is placed with its open fibrous side facing the prepared lesion site. Cartimaix is fixed by digitally pressing to the fibrin glue. Additional fixing by interrupted sutures is usually not necessary, but the decision is depending on the respective operating situation and left to the preference of the surgeon. Subsequently after adhesion by the fibrin glue (about 5 minutes), the correct placement of the membrane is checked by moving the joint 10 times.
If required a redon drainage can be applied for 24 hours (without suction). Wound closure and if indicated the application of an immobilizing orthesis complete the surgery.
* The individual treatment by the surgeon may vary partially from this described procedure. The general principles of sterile handling, applicable patient medication and the general surgical techniques must be followed. Please note the Instructions For Use accompanying the product and the Limitations of Use contained therein.
NanoFx® is a trademark of Arthrosurface, Inc. (USA)