## 4 Discussion  
The overall aim of this study was to engineer a porous scaffold with comparable properties to that of native cartilage and understand the effects of degradation on the physiochemical and mechanical properties of cartilage tissue engineering. First, a porous scaffold (porosity \(\sim\)86%) was fabricated by 3D printing. The utilisation of 3D printing to fabricate scaffolds has the benefit of enabling defined architectural structures, including specialised models for cartilage tissue engineering. Pore interconnectivity has been shown to have a favourable impact on cell proliferation, migration, and infiltration depth, and a high degree of porosity (\(\sim\)90%), with an open pore network, is best for interacting and integrating with the host tissue [28; 29]. The scaffold displayed open pores and an interconnected polymer network with minimal defects in the polymer matrices (Figure 1c,e), with the ramp, equilibrium, and dynamic moduli of the scaffold being comparable with the native cartilage suggesting its suitability to be utilised for cartilage tissue engineering [30; 31; 32; 33]. Figure 13: Effect of accelerated degradation on compressive properties (n = 4, Ave \(\pm\) std. dev. ). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{47 \({}^{\circ}\)C} & Degradation & \multirow{2}{*}{0} & \multirow{2}{*}{3} & \multirow{2}{*}{7} & \multirow{2}{*}{10} & \multirow{2}{*}{14} & \multirow{2}{*}{21} & \multirow{2}{*}{28} \\  & Time (Days) & & & & & & & \\ \cline{2-7}  & Mn (g/mol) & 125,481 & 92,506 & 76,770 & 64,700 & 53,481 & 23,584 & 9585 \\ \hline \end{tabular}
\end{table} 
Table 3: Molecular weight of scaffolds during degradation at 47 \({}^{\circ}\)C.  
To determine if a bioresorbable scaffold can provide adequate supporting functions within the timeframe necessary for tissue regeneration, monitoring the changes to the scaffold's overall characteristics over the degradation phase is crucial. The media chosen to perform the degradation studies was PBS. Although this solution does not replicate body fluid (the absence of enzymes that would be present in the host), studies in the past comparing the degradation profiles of polymers in PBS and in vivo found a close match [34; 35; 36]. On degrading the scaffolds at physiologically relevant conditions (37 \({}^{\circ}\)C), the scaffolds maintained their volumetric structure. This may be because a high porosity results in a low degradation rate in PLGA 85:15 [37], as the polyesters have an acid-catalysed process where the rate of degradation is dependent on the internal concentration of the acidic byproducts. In this study, a high diffusion rate from the porous scaffold may have resulted in a low buildup of acidic products, leading to a gradual degradation of the underlying scaffold. The degradation traits are in line with the heterogeneous degradation mechanism suggested by [PERSON] et al. [38]. On day 56 of degradation, the mass loss reported was within 10% for all the samples tested, which indicated that the scaffolds were still far from total breakdown and retained their original structure. [PERSON] et al. [9] reported swelling of the PLLGA 85:15 discs began only after a loss in mass; however, in this study, swelling occurred before any mass loss, which could be attributed to increased scaffold wetting due to high porosity. This may have resulted in the polyester linkages within the polymer chains being more vulnerable to hydrolysis by concentrating more water molecules close to them [19]. Since the flow of media in a scaffold is crucial for nutritional and metabolic exchanges in the articular cartilage, the capacity of a scaffold to absorb and retain water with minimal structural changes is a crucial property for creating a viable scaffold for cartilage tissue regeneration [28]. To further confirm the slow release of the acidic oligomers from the polymeric matrix, pH variation during the incubation time was evaluated, as local changes in acidity can influence the growth of tissues in vivo [3].