K. Lin (New York, US)Hospital for Special Surgery
Presenter Of 2 Presentations
10.2.8 - Magnetic Resonance Quantification of Meniscus Vascularity in Pediatric Versus Adult Knees
Despite advances in surgical techniques, implant technology, and biological augmentation, one innate limitation to meniscus healing is lack of vascularity. Ability to quantify meniscal vascularity has been limited with previous techniques, and minimal data exists describing differential vascular zones in the skeletally immature meniscus. The objective of this study is to use quantitative contrast-enhanced magnetic resonance imaging (MRI) to compare meniscal vascularity in pediatric specimens to adults. We hypothesize that the developing meniscus has greater and more uniform vascularity throughout all zones.
Methods and Materials
We utilized 10 fresh-frozen human cadaveric knees (5 immature knees, age 0-6 months; 5 mature knees, age 34-67 years). Gadolinium-enhanced MRI was performed using a previously established vascularity quantification protocol. Regions of interest corresponding to peripheral and central zones of the meniscus were identified on pre-contrast coronal images, and signal enhancement (normalized against background tissue) was compared between pre-and post-contrast images (Figure 1).
Quantitative MRI demonstrated increased perfusion in the peripheral zones compared to the central zones (2.3:1 in immature knees and 3:1 in mature knees) in the medial and lateral menisci separately, and both menisci aggregated (Figure 2). Overall, the medial and lateral menisci had similar levels of perfusion in all specimens (45.9% ± 8.3% medial vs. 54.1% ± 8.3% lateral in immature knees; 50.5% ± 11.3% medial vs. 49.5% ± 11.3% lateral in mature knees). Immature specimens demonstrated greater overall normalized meniscal signal uptake, with the 0-month specimen demonstrating the greatest proportional signal enhancement.
While blood flow to peripheral zones is greater than to central zones in both immature and adult menisci, younger menisci receive proportionally greater overall blood flow compared to adults, including greater blood flow to the inner zone, challenging the conventional wisdom of the central zone being avascular.
16.4.3 - Patellar Osteochondral Allograft Transplantation Using Femoral Hemicondyle Allografts: Magnetic Resonance and Clinical Outcomes
Osteochondral allograft transplantation (OCA) of the patella is limited by the availability of suitable size-matched patella donor tissue. The purpose of this study was to assess magnetic resonance imaging (MRI) and clinical outcomes of patients treated with non-orthotopic patellar OCA using a femoral hemicondyle (FH) donor.
Methods and Materials
A prospective institutional registry review identified 43 patients treated with patellar OCA using FH donor from 2009 to 2016. OCA plugs were harvested from FH at the trochlea-condyle junction and implanted using press-fit technique (Figure 1). Bone, cartilage, and ancillary features on postoperative MRI were graded by a blinded musculoskeletal radiologist using the Osteochondral Allograft MRI Scoring System (OCAMRISS). VAS, IKDC, and KOS-ADL scores preoperatively and at 1 year postoperatively were compared using the paired t-test.
Mean age was 36.6 years (range, 22 to 55 years), and mean body mass index 25.8 (range, 21.9 to 41.3), 61% female. Mean preoperative tibial tubercle to trochlear groove distance (TT-TG) was 14.0 mm (range, 5.5 to 19.8 mm). Donor specimens were 73%, 16%, and 11% lateral hemicondyle, medial hemicondyle, and whole distal femur allograft, respectively. On MRI at 11.4 months (range, 6 to 22 months) postoperative, mean total OCAMRISS score was 9.0 (range, 7 to 11). Mean bone, cartilage, and ancillary subscores were 2.6, 3.7, and 2.6, respectively. 59% of grafts demonstrated full osseous integration with crossing trabeculae and no discernable cleft, 65% demonstrated absence of cystic change at graft interfaces (Figure 2). At latest follow-up (mean 46.5 months, range 12-85 months), postoperative improvements in VAS (5.0 to 3.4; P=0.03), IKDC (45.4 to 63.0; P = 0.01) and KOS-ADL (62.7 to 75.1; P = 0.005) were noted.
OCA using non-orthotopic FH donor is a viable option for treatment of patellar osteochondral lesions, as it leads to improved pain and patient-reported outcomes, and good osseous incorporation on MRI.