Surgical Approach to Full Thickness Cartilage Defect With Patellar Instability: Combined Matrix-Associated Chondrocyte Implantation (MACI) and Medial Patellofemoral Ligament (MPFL) Reconstruction

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Background: Cartilage injury in the setting of acute patellar dislocation is a devastating condition that can lead to decreased quality of life and can progress to early osteoarthritis of the knee if not treated adequately. Indications: Matric-associated chondrocyte implantation (MACI) with concomitant medial patellofemoral ligament reconstruction (MPFLR) is indicated for young, high-demand patients with a symptomatic, full-thickness chondral lesions >2 cm2 that have failed an initial trial of conservative management or are found to have evidence of extensive cartilage damage or loose body that is not amenable to fixation. Technique Description: The MACI technique requires a 2-stage procedure. An initial diagnostic arthroscopy aids in characterization of the chondral lesion with regard to lesion size, depth, and morphology. Hyaline cartilage was harvested and autologous chondrocytes are seeded onto a MACI scaffold to grow. At the second stage, an MPFLR is planned alongside MACI. First a midline incision is made. Notably, instead of performing the capsulotomy at this stage, we proceed with the dissection for the MPFLR first creating a plane between layer #2 and #3 for easier graft retrieval later. The defect site is prepared, and the MACI graft is seated in the defect and secured. Medial patellofemoral ligament reconstruction is then begun by fixing the preloaded semitendinosus allograft to the patella. Shottle point is confirmed via fluoroscopy and dissection down to the femoral condyle is performed. The graft is retrieved between the 2 layers that were dissected earlier in the procedure and fixed within the femoral tunnel. Finally, the synovial layer is closed deep to the MPFL graft and the vastus medialis oblique (VMO) layer is closed superficial to it before closing the wound in the standard fashion. Results: The MACI procedure demonstrates high rates of satisfaction for relief of pain and significant improvements in clinical outcomes with generally low incidence of complications. Matric-associated chondrocyte implantation has been shown to be superior to microfracture in the treatment of larger (>3 cm2) symptomatic articular defects at 5 years. Discussion/Conclusion: Matric-associated chondrocyte implantation procedure with concomitant MPFLR should be considered in indicated patients with full thickness cartilage defects that are not amenable to fixation. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.