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Erschienen in:
03.06.2021 | Operative Techniken
Prone-positioned knee arthroscopy for isolated retropatellar cartilage defects with gel-type autologous chondrocyte implantation
Erschienen in: Operative Orthopädie und Traumatologie | Ausgabe 5/2021
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Objective
Treatment of isolated retropatellar cartilage defects using current gel-type regenerative methods requires settlement of the gel to the underlying subchondral bone under gravity; thus, prone positioned arthroscopy is used.
Indications
Isolated retropatellar contained cartilage defect size >2.5 cm2. Age <40 years, epiphyseal closure, cartilage defect grade 3/4 (International Cartilage Repair Society).
Contraindications
Cartilage defects at medial or lateral femorotibial compartments, at the trochlea, with degenerative genesis, rheumatoid arthritis, local infection, patellar malalignment, patellofemoral dysplasia, knee instability, knee malalignment >3°, kissing lesions.
Surgical technique
Two-stage procedure: At initial arthroscopy, chondrocytes were harvested. At the second stage, the patient was positioned prone and the leg with a thigh tourniquet was fixed in a leg holder. Removal of table extension below the knee and support of foot in sling to prevent knee hyperextension. Placement of 2 lateral portals. Lesion visualized and debrided, followed by aspiration of intra-articular fluid. A loop, placed posterior to the patellar ligament using a lasso, was used to suspend a weight to expand the patellofemoral space. The lesion was then dried using a sponge. NOVOCART® Inject (TETEC, Reutlingen, Germany) administered onto the defect. Gel was allowed to solidify for 15 min and operation was completed.
Postoperative management
Knee locked in extension using a brace for 6 weeks. Continuous passive motion applied and incrementally increased until full range of motion (ROM) at week 6. Weight-bearing as tolerated was allowed with the knee in extension. Routine clinical follow-up after 3, 6 and 12 months.
Results
Mean age of the 5 patients was 23 ± 6 (range 14–30) years; mean follow-up time after surgery 28 ± 7 (range 20–40) months. All patients returned to full activity without residual knee ROM restriction. Clinical examination at the latest follow-up revealed a Kujala score of 90 ± 12 points and Lysholm score of 95 ± 5 points. MRI showed filled cartilage defects in all patients. Mocart score was 63 ± 7 points. Cartilage was inhomogeneous and hyperintense at the repaired site. Quantitative measurement of the patella mobility of the operated knee under a translating force of 10 N showed medial and lateral displacements of 21 ± 5 and 15 ± 2 mm and on the healthy side 22 ± 5 and 19 ± 3 mm, respectively.