Functional MRI techniques can be applied to noninvasively assess the biochemical health of cartilage after osteochondral allograft transplantation. The MRI findings correlated with certain patient-reported outcomes in the early postoperative period. Relative glycosaminoglycan content and the collagen structure of allograft cartilage may undergo time-dependent degeneration. A patient's perception of clinical outcome and quality of life is likely multifactorial and is impacted by more than the health of the allograft cartilage.
To best re-create the native glenohumeral anatomy, surgeons should consider the use of an autograft of the inferior coracoid or an osteochondral allograft of the lateral distal tibia for the reconstruction of osseous glenoid defects.
Bipartite patella can be classified into three unique subtypes; type I, II, and III. The following case series describes three representative cases of each subtype and a spectrum of location-specific treatment options for surgical care of the symptomatic bipartite patella.
The protocol for delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) was adapted for the evaluation of transplanted osteochondral allograft cartilage. Eight patients with focal grade 4 cartilage defects of the femoral condyle were treated with single cylindrical osteochondral allografts. At 1 and 2 years, dGEMRIC image sequences were acquired and regions of interest (ROIs) were drawn in repair and native control cartilage. Mean T1 values of region of interest were used to calculate established dGEMRIC metrics. The correlation was measured between the ΔR1 and R1 -Post metrics for repair and native cartilage. T1 times were measured in deep and superficial zones of cartilage. A strong correlation was identified between full-thickness, deep, and superficial ΔR1 and R1 -Post values for native cartilage and repair cartilage for all years (range: 0.893-1.0). The mean T1 times and ΔR1 rate between deep and superficial regions of articular cartilage were statistically different for all regions of the distal femora analyzed at 1 year and 2 years after osteochondral allograft transplantation (P<0.05). The dGEMRIC pre-Gadolinium scan is unnecessary when evaluating transplanted osteochondral allograft cartilage. The observation of stratified T1 and ΔR1 values indicates a need to re-evaluate the methodology behind the placement of region of interest in dGEMRIC.
This algorithm can be applied to any 2D- or 3D-IR acquisition sequence used in conjunction with dGEMRIC. Application of the algorithm improves the reliability of T1 calculations and allows the number of TIs to be reduced, leading to shorter scan times in dGEMRIC.
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