Mechanobiology of indirect bone fracture healing under conditions of relative stability: a narrative review for the practicing clinician.

BACKGROUND AND AIM: Mechanical influence on secondary fracture healing remains an incompletely understood phenomenon. This is of special importance in biological osteosynthesis, where stability is sacrificed for the sake of an optimal biological fracture environment. Under condition of relative stability, a wide range of biomechanical conditions can be achieved. Mechanobiology, which studies mechanical influences on biological systems has become a large, interdisciplinary field. The aim of this article is to present a comprehensive synthesis of the literature for the practicing clinician, with insights relevant to their practice of fracture care. METHODS: The MEDLINE online database (Pubmed) was searched in September 2021 for relevant articles Results: The search provided 816 results, which were scanned by the first author by the title and abstract. With relevance to the research topic, 59 articles were chosen and read in detail. Another 70 articles were added by screening the references of relevant articles. A total of 129 articles were read and analysed Conclusions: Mechanical environment plays a crucial role in the fracture healing process. The definition of an optimal mechanical environment still evades us, due to the complexity of the problem. Computational models could replicate the complex mechanical environment of bone healing in humans but require detailed knowledge of mechano-transduction and material properties of healing tissues. The literature reminds us of the importance of adequate stiffness of constructs used under conditions of relative stability. Hopefully, further research in this field will result in not only empirical but more accurate and evidence-based assessments of osteosynthesis fixations.

Reduction of trochanteric fractures in lateral view is significant predictor for radiological and functional result after six months.

OBJECTIVES: The goal of our retrospective study was to determine which radiological parameter after fixation of trochanteric fractures type AO 31 A2 is most important for the position of the fracture after six months. The additional goal was to find how the end position influences mechanical failure and the mobility of the patients. PATIENTS AND METHODS: We analysed 92 patients operated in one-year period for A 2 type trochanteric fractures with sliding hip screw or proximal femur intramedullary nail. They were divided in two groups according to the radiological position of the proximal fragment six months after the surgery. In group A we had 46 patients with satisfactory and in group B 46 patients with unsatisfactory position. In anteroposterior view we evaluated neck-shaft angle (NSA) and medial cortical support (MCS) and in lateral view anterior cortical support (ACS). Unsatisfactory position was recognized if NSA was in varus or ACS or MCS were negative. We compared the groups regarding basic patients characteristics (age, gender, ASA score, preinjury mobility, and degree of osteoporosis), type and quality of fixation, the position of the fracture (postoperatively and after 6 months), mechanical failure and mobility after 6 months. Statistical significance level was set to p ≤ 0.05. RESULTS: Basic patients' characteristics as well as type and quality of fixation did not significantly differ between the groups. After the injury the difference between the groups in reduction quality was significant in lateral view (ACS; p=0.001), while after half a year there were significant differences in both views: NSA (p=0.003), ACS and MCS (both p<0.001). Proximal fragment position after six months statistically significant correlated with postoperative ACS in B group (r = 0.386, p = 0.008), but not with NCA nor with MCS. There were also significantly more fixation failures in group B (p<0.001) and less patients regain preinjury mobility (p=0.029). CONCLUSIONS: In trochanteric fractures reduction in lateral view is the most important prognostic factor for favourable radiological result after half a year. Unsatisfactory position of the proximal fragment after six months influences mechanical failures and walking ability.

Patient-specific template and electromagnetic navigation assisted bilateral periacetabular osteotomy for staged correction of bilateral injury-induced hip dysplasia: a case report.

Periacetabular osteotomy (PAO) for pelvic fracture sequelae presents a challenge in hip preservation surgery due to a combination of complex conditions involving post-traumatic altered anatomy and technically demanding procedure, with high surgical risk involved. To address these challenging conditions and evade potential devastating complications, a combination of patient-specific template (PST) and electromagnetic navigation (EMN) guidance can be used to increase the safety of the procedure and the accuracy of the acetabular reorientation. Herein we report our experience utilizing a combined PST- and EMN-assisted bilateral PAO for staged correction of bilateral severe, injury-induced hip dysplasia. The presented case report describes a unique method of successful surgical treatment of severe, bilateral injury-induced hip dysplasia with combined 3-D printing technology (PST) and intra-operative electromagnetic computer-assisted navigation (EMN) aided technically demanding surgical procedure (PAO), which emphasizes the benefits of PST and EMN use in hip preservation surgery in patients with complex pathoanatomic circumstances.

Management of acute bone loss following high grade open tibia fractures.

INTRODUCTION: Optimal treatment for acute post-traumatic bone loss in the tibia remains unclear. Distraction osteogenesis (DO) and induced membrane technique (IM) have been established as the mainstays of treatment. Aim of this article is to review the current evidence regarding the use of these two methods. METHODS: A review of the MEDLINE database was performed with strict inclusion and exclusion criteria focusing on treatment of the acute bone loss after open tibia fractures with DO and IM. Bone union rate was taken as the primary outcome and infection rate as secondary outcome. RESULTS: Four studies out of 78 on the use of the DO and three studies out of 18 on the use of the IM technique matched the inclusion criteria. Union rate in the DO group ranged between 92% and 100%, with infection rates between 0 and 4%. In the IM group, union was reached in 42% to 100% of cases, with septic complications occurring in 12% to 43%. Differences in union rate and infection rate reached statistical significance. DISCUSSION: We found a considerable evidence gap regarding treatment of bone loss in high grade open tibia fractures. The limitations of our study prevented us from drawing clear causative conclusions on the results. Although our study points to higher union rates and lower infection rate with the use of the DO technique, the results remain preliminary and further high-level evidence is needed to establish the roles of DO and IM in treatment of acute bone loss in open tibia fractures.