Special Issue “Advanced Imaging in Orthopedic Biomechanics”

Continued advances in medical imaging are increasingly resulting in promising developments, for example in producing high-resolution visualization of musculoskeletal systems and thus having a high impact in clinical assessments [1,2,3,4,5]. This is accompanied by a significant reduction in invasiveness, for example in ionizing radiation [6,7], as well as a decrease in cost and improved device ergonomics [8,9]. As such, advanced imaging techniques have become increasingly popular clinical diagnostic tools among orthopedists, physiatrists, and physical therapists [4,5]. They are also becoming an integral part of many biomechanical studies in orthopedics due to their potential positive developments regarding functional assessments, as well as for many new and original highly innovative applications [10,11,12]. The latter includes the planning and the execution of personalized and minimally invasive surgeries supported by three-dimensional printing of implantable medical devices [13,14,15,16]. Advanced imaging also indicates the necessity for representative computational models of highly complex musculoskeletal systems for use in clinical applications or to understand biomechanical behaviors that are still controversial or not entirely clear [17,18]. To this end, the purpose of this Special Issue was to gather studies in which the biomechanics of the human body are highly supported by new, more advanced and accurate medical imaging systems [19,20] and relevant data processing techniques [21,22,23,24]. Taking into consideration the entire kinetic chain of the human body, including the totality of interconnected parts (i.e., joints, muscles, and ligaments) and how they work together to execute a specific movement, advanced imaging has been involved in every area and application with interesting and original implications. Starting from the trunk of the human body, including the spine, numerical simulations using finite element analysis based on cranio-cervical computed tomography data have enabled observations of how intervertebral disc wear has affected the biomechanical response of the cervical region, providing useful information on possible force-related injuries to potentially be used to propose better physiotherapy procedures [Contributions 1]. In a very multifactorial way, it is possible to relate the shape of the intervertebral foramina to factors such as age, sex, and motor neuron level to improve conservative and surgical treatment of spinal pathologies using computed tomography [Contributions 2]. Staying in the context of the spine, guidelines can be identified for the development of a more accurate spinal deformity assessment method to improve the diagnosis of scoliosis [Contributions 3]. Cervical vertebral bone mineral density and related age-dependent changes can be detected with alternative tools based on cone-beam computed tomography to diagnose osteoporosis [Contributions 4]. Moving down to the hip, and specifically to related bone oncology, the combined use of computed tomography and magnetic resonance imaging allows for consistent overall surgical procedures, through pre-surgical virtual planning and design of patient-specific surgical instrumentation, for massive hip reconstruction with safer margins for tumor removal [Contributions 5]. Regarding the knee, a joint that should be more appropriately studied under loaded conditions, dynamic MRI represents an emerging technology that should be given much more consideration for safe investigations of the functional interaction between the hard and soft tissues of the joint [Contributions 6]. On the other hand, it has again been confirmed that knee MRI data can be used in finite element analysis to obtain interesting information on the effect of varus/valgus loading configurations in bones after total knee arthroplasty with a hinged implant design [Contributions 7]. By moving even further distally, the overall biomechanics of the ankle–foot complex can be further studied and more thoroughly understood with the help of cutting-edge medical imaging techniques. Indeed, it has been shown that, in the context of dynamic modeling of the human ankle, the mechanical behavior of the joint obtained with the ligament attachment sites of the ankle detected by MRI at 3.0 T is closer to that obtained by direct observation than that obtained by MRI at 1.5 T [Contributions 8]. On the other hand, the importance of cone-beam technology for computed tomography under weight-bearing conditions in the foot and ankle has been extensively reported in two reviews. In detail, a critical discussion of the evidence provided so far in terms of advantages, limitations, and future areas of development is provided [Contributions 9], as well as promising advances in new three-dimensional techniques for automated measurements and bias reduction, particularly for syndesmotic measurements [Contributions 10]. Remaining in the context of the foot, due to the ability of computational models to accurately predict tissue behavior under concrete circumstances, more precise knowledge of foot pressure behavior has been provided through engineering methods that rely on medical imaging data, such as computed tomography, to create customized prosthetic devices and orthoses [Contributions 11]. Similar conclusions can be extended to the upper extremities, particularly the elbow and its biomechanics [Contributions 12].

Through this Special Issue, the guest editors hope to have drawn attention to the relevance of new and more accurate advanced medical imaging techniques, both in orthopedics and related biomechanical evaluations. The authors’ contributions covered different anatomical compartments and various data processing methodologies, highlighting the multidisciplinary and translational nature of investigative procedures. This not only confirms that medical imaging is broadly supportive of biomechanical research but that the two are synergistic with each other in identifying better treatments for patients, with psychosocial and economic benefits for the population as a whole.