Since the functional link of bone structure and mechanics starts at the nanoscale, bulk mechanical techniques examining whole bone samples will fall short in isolating the effect of molecular- and fibrillar-level modifications on bone mechanics. For nano- and micromechanical testing, nanoindentation using atomic force microscopy (AFM) and micropillar compression are attractive candidates. When coupled with SEM imaging, these techniques can help visualize crack growth upon fracture ex situ and _in operando_[11; 47]. By combining EM imaging, chemical nano-/micro-analysis, and mechanical testing of pathological bone, we can gain insights into a wide range of disease states at the bone ultrastructural level and possibly understand their origin. By analogy, characterizing bones from animals/patients treated with antiresorptive drugs, for instance, bisphosphonates, can help explain the effects of these therapeutics on bone structure and mechanics--especially considering that the long-term complications from their use remain less understood--and clarify how and to what extent they help repair diseased bone tissues [48; 49]. There exists extensive literature on the multiscale characterization of healthy, normal bone tissues (Figure 1), as reviewed by others [50; 51; 52]. However, there is no systematic review emphasizing nanoscale imaging and analysis in the context of bone pathologies. In this review, we first recount the current knowledge on the roles of NCPs in bone. Next, the structural and mechanical characteristics of pathological bone tissues are discussed in relation to their healthy counterparts, highlighting the importance of ultrastructural imaging and analysis as well as the outstanding challenges in understanding bone diseases at the nanoscale. As recognizing the effects of molecular alterations in pathologic bone is critical to the design of effective, targeted therapeutics, we then discuss current and prospective strategies for repairing diseased bone. Finally, we conclude by summarizing what is known and what remains unanswered in understanding bone pathologies, starting from the nanoscale, and offer some perspectives on this topic. \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Characterization Techniques**} & \multicolumn{1}{c}{**Illustrative Examples of Information Acquired**} \\ \hline Energy dispersive X-ray (EDX) spectroscopy & \(\bullet\) & Elemental microanalysis: e.g., quantification of Ca/P ratio [14] \\  & \(\bullet\) & Similar Ca content in the cement line interior compared to interstitial or osteonal bones [22] \\ \hline Quantitative backscattered electron imaging (qBEI) & \(\bullet\) & Degree of mineralization and mineral content distribution [35; 36] \\ \hline Raman spectroscopy and mapping & \(\bullet\) & Raman biochemical signatures for the mineral and matrix (including proteoglycans and lipids) constituents of bone, and their quantitative analysis [37; 38] \\  & \(\bullet\) & In situ transcutaneous analysis of mineral and organic contents of underlying bone [39] \\ \hline Infrared spectroscopy and mapping (e.g., Fourier-transform, FTIR) & \(\bullet\) & In situ quantification of mineral content (e.g., mineral-to-matrix stoichiometry) and crystallinity of bone [40; 41] \\  & \(\bullet\) & Spatial mapping of crystalline contents [41] \\  & \(\bullet\) & Spatial variation in collagen maturity by measuring the ratio of immature-to-mature crosslinking [42] \\ \hline Atom probe tomography (APT) & \(\bullet\) & Chemically and spatially heterogeneous mineralization in bone, showing dispersed Ca-rich and -deficient clusters of size \\  & \(\bullet\) & Co-localization of Na with the mineral–collagen interface [43] \\ \hline Secondary ion mass spectroscopy (SIMS) and imaging & \(\bullet\) & Quantification and spatial mapping of organic fragment content (e.g., Ca\({}^{2+}\), Ca\({}_{4}\)H\({}_{8}\)N\({}^{+}\)) in bone at mm scale [44] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._