Abstract
Background:
Microfracture is an established technique for cartilage regeneration but is limited by many factors such as small defect size, intralesional osteophytes, and lower quality of cartilage regeneration. Therefore, methods to improve results after microfracture like additional matrix augmentation or autologous cell addition are promising techniques. An all-arthroscopic surgical technique for matrix-augmented bone marrow stimulation will be presented here.
Indications:
Cartilage lesions of moderate size (>1 cm2) that appear too large or unsuitable for pure microfracture but do not yet meet the criteria for autologous cartilage transplantation (>2.5 cm2). The exact size of suitable lesions is currently evolving with only few evidence-based data available.
Technique Description:
The arthroscopic procedure largely follows the standard microfracture technique. First, the cartilage defect is extensively debrided with removal of calcific cartilage layer. Stable cartilage margins have to be created with removal of all unstable fragments. The resulting well-defined defect is then measured with the use of a marking probe. The subchondral bone is then penetrated and opened using a microfracture awl. Next, the matrix based on hyaluronic acid (Hyalofast) is cut to the appropriate size. All joint fluid is removed, and the matrix is inserted through a previously placed canula and modeled into the defect with the probe. When the defect is well contained, no other fixation material is necessary. Otherwise, the matrix can be additionally fixed using fibrin clue. Cell application (dependent on regulatory issues) can be performed. Before closure, the joint should be moved to ensure safe fixation of the matrix.
Results:
Currently, there are only insufficient data to exactly define the defect size for microfracture or matrix-assisted bone marrow stimulation. Some studies show an advantage of using biomaterials compared with microfracture alone, but further studies are necessary.
Discussion/Conclusion:
The presented arthroscopic matrix-assisted bone marrow stimulation is a technically simple, inexpensive way of treating cartilage defects and should therefore be considered when treating affected patients. It can be used in a variety of joints. An additional combination with bone marrow–derived mesenchymal stem cells might be promising but is subject to country-specific regulatory issues.
This is a visual representation of the abstract.
Video Transcript
Hi everyone,
Thanks for watching our video demonstrating the surgical technique of arthroscopic matrix-assisted bone marrow stimulation for cartilage defects by Chris Lutter, Robert Lenz, and Thomas Tischer from the University of Rostock, Germany.
There are no relevant disclosures.
In a nutshell: Microfracture might be improved by matrix augmentation. The indication is cartilage lesions greater than 1 cm2. For the arthroscopic technique: First, perform a standard microfracture technique, followed by preparation of the hyaluronic matrix, removal of joint fluid, insertion of the matrix, and final check of stability. Regarding the results, there is currently only limited evidence regarding the long-term outcome. Conclusion: This is a simple and inexpensive technique that can be used in different joints; additional stem cell application is possible but subject to regulatory issues.
The presented case is a 27-year-old woman. She had a trauma during cross-fit 2 months ago. Anteroposterior and lateral radiographs (non-weightbearing) were unremarkable. Her clinical presentation was also quite normal, with a full range of motion, stable joint, and a straight weightbearing axis with intermittent clicking during movement. The magnetic resonance image showed a 1.3 × 1.6 cm full-thickness cartilage defect of the lateral femoral condyle.
The patient was scheduled for arthroscopic treatment performed without leg holder and using a tourniquet. Arthroscopy showed a healthy femoropatellar and medial compartment and the cartilage lesion on the lateral femoral condyle. A huge free cartilage body (1.2 × 1.5 cm) was identified and removed.
Improved visualization can be achieved using a shaver. Next, a probe can be used to identify unstable cartilage margins that should be removed using a sharp rongeur, which provides the advantage of undermining the unstable flaps and creating sharp margins.
Now, sizing of the defect is important to establish the indication for matrix-assisted bone marrow stimulation, which should be greater than 1 cm2 to justify the additional costs of the matrix with currently no evidence-based defined upper size limits.
Defect preparation is performed using different-sized curettes, removing the calcified cartilage layer and creating sharp margins to healthy cartilage.
The Hyalofast matrix from PlasmaConcept (Germany), which is available in 2 sizes of 2 × 2 and 5 × 5 cm, is then cut to the appropriate size using scissors and checked with a ruler.
Within the following step of the procedure, the bone marrow penetration is performed using a standard microfracture technique using awls with 3- to 4-mm distance in between the holes. Drilling of the subchondral bone using, for example, Kirschner wires represents an alternative technique.
A cannula is then introduced into the joint for easy insertion of the matrix later on. The arthroscopic fluid is removed by suction, for example, with the shaver.
The defect is visualized, and the matrix, prepared and cut to the appropriate size as shown before, is inserted into the knee joint. This step is performed using an arthroscopic grasper. The grasper is then removed and replaced by an arthroscopic probe. This probe is now used to carefully mold the matrix into the prepared cartilage defect. The matrix subsequently absorbs blood and becomes increasingly sticky, which simplifies modeling. The entire process, shown here in real time, is quite simple and fast. Continuous modeling is performed to perfectly fit the matrix into the defect.
The final aspect of the matrix can now be seen, and the joint is moved to check for stability of the matrix. If there are any concerns for instability, additional fibrin glue fixation can be used. Also, additional stem cell augmentation can be performed if permitted by regulatory authorities. The skin is then sutured in a standard fashion. No drain is used.
This technique can also be combined with bone grafting or used in other compartments of the knee such as the patella as well as other joints such as ankle, shoulder, or hip.
Specific complications that differ from a standard microfracture procedure could be the following: delamination of the matrix and insufficient cartilage regeneration, especially with insufficient rehabilitation. Potential allergic reactions to the matrix might occur but have not been reported to the best of our knowledge so far.
The rehabilitation is similar to other cartilage regenerative procedures. We recommend initial joint immobilization for 1 to 2 days to secure the matrix fixation. The time of non-weightbearing or limited weightbearing depends greatly on the size and location of the defect and is recommended for up to 6 to 9 weeks. Continuous passive motion is recommended between 3 and 6 weeks. Return to sport also greatly depends on cartilage defect size, location, and sports performed (eg, biking vs soccer).
Studies described a benefit in favor of matrix augmentation when directly comparing matrix augmentation versus microfracture alone after 2 years (Sofu et al) and 5 years (Volz et al). The use of the Hyalofast matrix and additional bone marrow aspirate concentrate is a viable and effective option that is mainly affected by lesion size and number and not by age as shown by Gobbi et al. However, the current evidence is overall insufficient for matrix-assisted bone marrow stimulation, and further studies are required.
On this last slide, we present the recommended literature on the topic presented in this video.
We hope you enjoyed our video, and if you have any questions or comments, feel free to contact us!
Footnotes
Submitted February 25, 2021; accepted March 1, 2021.
One or more of the authors has declared the following potential conflict of interest or source of funding. T.T. is a paid consultant for Arthrex and Bauerfeind. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
