PMC9619140_01
MRI of the right knee presurgical. (A) 60 to 70% incomplete radial/flap tears in the posterior horn of the medial meniscus with a flap tear component in direction to the pars intermedia. (B) Arthroscopic evaluation of the right knee after partial meniscectomy with the 18 x 8 mm defect.
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Fig. 1A shows the MRI of the right knee presurgery. Fig. 1B shows the right knee after partial meniscectomy with the 18 x 8 mm defect. Tibial Osteotomy (HTO, with TomoFixTM, DePuy Synthes, Oberdorf, Switzerland) was performed and at the same time, after partial meniscectomy (Fig. 1B) the patient was arthroscopically treated with implantation of a demineralized bone block (Spongioflex(R), 18x10x6mm, DIZG gGmbH, Berlin, Germany) as a partial medial meniscus substitute (Fig. 2). The block was secured with 4 inside-out sutures (Etibond 0, Ethicon, Somerville, NJ).
MRI of the right knee 7 weeks after surgery. (A) Slight hyperintense signal of the implant; violet line: implant length; red line: whole length of meniscus in sagital plane; (B) axial reconstruction showing the sagittal plane level (green line: AP-implant length) of A, red line: length of the block.
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MRI on the right knee was performed as scheduled after 7 weeks, 16 weeks, and 1 year postoperatively. MRI examination on the right knee, 7 weeks (Fig. 3) after surgery, showed only a slight hyperintense signal with no visible reduction of the implant size.
MRI of the right knee 16 weeks after surgery. (A) Isointense signal of the implant, yellow line. Implant length, green line: whole meniscus length in sagital plane; (B) axial reconstruction showing the sagittal plane level (blue line) of A.
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Four- and 12 months postsurgery, it was not possible to distinguish the implant and native meniscal tissue in the sagittal plane, because of the isointense signal (Figs. 4 and 5).
MRI of the right knee 12 months after surgery. (A) Isointense signal of the implant compared to the anterior horn, green line: whole length meniscus, implant not any more visible. (B) Axial reconstruction showing the sagittal plane level (green line) of A.
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Four- and 12 months postsurgery, it was not possible to distinguish the implant and native meniscal tissue in the sagittal plane, because of the isointense signal (Figs. 4 and 5).
MRI of the left knee presurgical. (A) 60 to 70% incomplete radial/flap tears in the posterior horn of the medial meniscus with a flap tear component in direction to the pars intermedia. (B) Arthroscopic evaluation of the right knee after partial meniscectomy with the 13 x 10 mm defect.
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Fig. 6A shows MRI of the left knee presurgical and Fig. 6B the left meniscus after partial meniscectomy. After partial meniscectomy (Fig. 6B), a demineralized bone block (13 x 10 x 6 mm, Spongioflex(R), Fig. 7) was implanted into the defect of the posterior horn (no HTO performed).
Demineralized bone block in situ after fixation on the left knee.
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The block was secured with 4 inside-out sutures (Etibond 0) as described above (Fig. 7).
MRI of the left knee 6 weeks after surgery. (A) Isointense signal of the posterior horn, green line: whole length meniscus, implant not any more visible. (B) Axial reconstruction showing the sagittal plane level of A. Radial tear still visible (white arrow).
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The MRI of the left knee, 6 weeks (Fig. 8) and 3 months (Fig. 9) postsurgery showed an isointense signal of the posterior horn of the medial meniscus. The radial tear was visible after 6 but less after 12 weeks, Figs. 8 and 9, respectively.
MRI of the left knee 12 weeks after surgery. (A) Isointense signal of the posterior horn, blue line: whole length meniscus, implant not any more visible. (B) Axial re-construction showing the implant and the plane level of A, radial tear less visible than after 6 weeks (white arrow), violet line: block length of implant; red line: whole length meniscus, implant block visible in this axial reconstruction.
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Instead, the implant was clearly visible in the axial reconstruction after 12 weeks (Fig. 9). The radial tear was visible after 6 but less after 12 weeks, Figs. 8 and 9, respectively.