Anatomical and Biomechanical Stability of Single/Double Screw-Cancellous Bone Fixations of Regan-Morry Type III Ulnar Coronoid Fractures in Adults: CT Measurement and Finite Element Analysis

Intelligent anatomic design of porous radial head prosthesis and microscopic-macro biomechanical finite element analysis in the long-term after replacement surgery

BACKGROUND

The microporous structure of porous titanium alloy may affect osteoblast differentiation and reduce effective elastic modulus (EEM) of the prostheses. Therefore, the biomechanics-based anatomic design of porous radial head prosthesis (PRHP) may help promote bone healing and reduce postoperative complications.

METHODS

A microscopic-macro virtual testing platform (VTP) was built to design cells with excellent mechanical properties, further, to construct the PRHP. An intelligent anatomic platform of healthy human elbow-forearms was developed to construct finite element (FE) models of solid radial head prosthesis (SRHP) and PRHP replacement for Mason type III fractures. Axial and valgus loads were applied for surgical model validation and microscopic-macro biomechanical analysis.

RESULTS

The order of ultimate compressive load (UCL) and yield strength (YS) of five types of cells is NEWTET>KAGOME>NEWPYRAMID>TET>PYRAMID. Under the same porosity conditions, UCL and YS of the double and four-layer lattice structures of NEWTET decreased by 62.39%, 69.46% and 61.70%, 70.21% compared to the single-layer, respectively. The EEM of NEWTET-based PRHP is 17.66% of that of SRHP. Compared with the SRHP replacement, PRHP replacement reduced the humeral cartilage stress by 18.96%-19.51%.

CONCLUSIONS

NEWTET cell has better microscopic mechanical properties and bone-growth adaptability. The EEM of NEWTET-based PRHP closely resembles cortical bone. Compared with SRHP replacement, microscopic-macro biomechanical performance in long-term after PRHP replacement is closer to that of a normal elbow joint. The microscopic-macro VTP and human intelligent anatomic elbow-forearm FE analysis systems provide efficient, accurate, and smart tools for the design of porous prostheses in joint replacement surgery.

Surgical Treatment of Coronoid Fracture With Elbow Varus Posteromedial Rotatory Instability: An Instructional Review

Varus posteromedial rotatory instability (VPMRI) of the elbow is one of the complex elbow instability. The primary sites of injury encompass fractures of the anteromedial coronoid process and injuries to the lateral collateral ligament of the elbow. Some patients may present with involvement of the medial collateral ligament of the elbow. Owing to its distinctive injury mechanism and imaging characteristics, this condition is infrequent in clinical practice and susceptible to misdiagnosis and missed diagnosis. Literature reviews indicate that conservative management of VPMRI is associated with numerous complications, such as persistent pain, traumatic arthritis, and chronic elbow instability. Consequently, surgical intervention has emerged as the recommended treatment modality. Nonetheless, the lack of systematic research on VPMRI in clinical practice has been inconclusive regarding the optimal internal fixation techniques and surgical approaches. Therefore, investigating the treatment modalities, surgical techniques, and internal fixation strategies for VPMRI associated with coronoid fractures holds substantial importance for informing clinical management. In this review, we systematically synthesize the existing literature on coronoid fractures with VPMRI for offering a valuable reference for future clinical treatment.

Digital smart internal fixation surgery for coronal process basal fracture with normal joint spaces or radius-shortening: Occult factor of radius-ulna load sharing

BACKGROUND

Reasonable postoperative humeroradial and humeroulnar joint spaces maybe an important indicator in biomechanical stability of smart internal fixation surgery for coronoid process basal fractures (CPBF). The aim of this study is to compare elbow articular stresses and elbow-forearm stability under smart internal fixations for the CPBF between normal elbow joint spaces and radius-shortening, and to determine the occult factor of radius-ulna load sharing.

METHODS

CT images of 70 volunteers with intact elbow joints were retrospectively collected for accurate three-dimensional reconstruction to measure the longitudinal and transverse joint spaces. Two groups of ten finite element (FE) models were established prospectively between normal joint space and radius-shortening with 2.0 mm, including intact elbow joint and forearm, elbow-forearm with CPBF trauma, anterior or posterior double screws-cancellous bone fixation, mini-plate-cancellous bone fixation. Three sets of physiological loads (compression, valgus, varus) were used for FE intelligent calculation, FE model verification, and biomechanical and motion analysis.

RESULTS

The stress distribution between coronoid process and radial head, compression displacements and valgus angles of elbow-forearm in the three smart fixation models of the normal joint spaces were close to those of corresponding intact elbow model, but were significantly different from those of preoperative CPBF models and fixed radius-shortening models. The maximum stresses of three smart fixation instrument models of normal joint spaces were significantly smaller than those of the corresponding fixed radius-shortening models.

CONCLUSIONS

On the basis of the existing trauma of the elbow-forearm system in clinical practice, which is a dominant factor affecting radius-ulna load sharing, the elbow joint longitudinal space has been found to be the occult factor affecting radius-ulna load sharing. The stability and load sharing of radius and ulna after three kinds of smart fixations of the CPBF is not only related to the anatomical and biomechanical stability principles of smart internal fixations, but also closely related to postoperative elbow joint longitudinal space.