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.

Should age be a factor in treatment choice of periprosthetic Vancouver B2-B3 proximal femur fractures? A retrospective analysis of mortality and functional outcomes in elderly patients.

Background and aim of the work Revision Arthroplasty (RA) is considered the treatment of choice for periprosthetic femur fractures (PFF) presenting with a loose stem. In the elderly RA may be associated with high post-operative mortality and complications. The aim of this study is to compare mortality and functional outcomes of open reduction internal fixation (ORIF) and RA for B2-B3 PFF in the elderly. Methods The study population included 29 patients (>65 years) surgically treated for B2-B3 PFF at the Orthopedic and Traumatology Unit of Cattinara University Hospital in Trieste (Italy) between January 2015 and December 2019. 16 patients were treated with ORIF and 13 with RA. Mortality and functional outcomes were analyzed. Results In-hospital (6,25% vs 7,69%) and 3 months (6,25 vs 15,38%) mortality was higher in the RA group. Mortality rates were particularly high in the > 85-year-old patients within four months from RA treatment. One year (38,46% and 16,67%) and overall mortality (69,22% and 25%) was higher after ORIF. Average time to weight-bearing and ambulation was 2.6 and 5.25 months for ORIF patients and 1.3 and 2.4 months for RA. A correlation was found between delayed weight-bearing and overall mortality. Conclusions Age is a risk factor for short term mortality following RA. Patients >85 years of age could benefit from a less invasive procedure such as ORIF. Long term outcomes are generally better for patients who undergo RA but further studies are necessary to evaluate the risk-benefit ratio of RA treatment compared to ORIF in elderly patients.

When does hip fracture surgery delay affects the length of hospital stay?

PURPOSE: To define factors influencing length of hospital stay (LOS) besides surgery delay. METHODS: We retrospectively analyzed 634 patients operated for hip fractures in 1-year period. Investigated characteristics were age, gender, American Society of Anesthesiologists score (ASA), time to surgery (first 48 h was considered early), type of surgery, anticoagulant therapy and non-routine pre-operative tests. Univariate and multivariable analysis were performed. p values < 0.05 were considered statistically significant. RESULTS: Median LOS was 12 days. Patients operated within 48 h had a LOS of 10 days, while patients operated after 48 h had 4 days longer LOS (p < 0.01). In multiple regression analyses, it was predicted that patients operated after 48 h with every 10 h delay to surgery had 7.3 h longer hospitalizations. All other factors did not influence the LOS. In early operation group, patients with hip arthroplasty had 3.3 days longer hospitalization compared to patients with osteosynthesis, every higher ASA score was associated with 1.4 days longer hospitalization, patients on anticoagulant therapy had 2.6 days longer LOS but surgery delay had no influence on LOS. Preinjury residence at a nursing home was associated with 4.4 days shorter hospitalizations compared to preinjury residence at home in both time frames. CONCLUSIONS: In patients operated in first 48 h longer LOS is associated with ASA, anticoagulant therapy and operation type but not with delay to surgery. If patients are operated after 48 h, surgery delay is the only factor increasing LOS.

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.

Operative treatment of acute shaft and neck lesser metatarsals fractures: a systematic review of the literature.

PURPOSE: Metatarsal fractures are relatively common injuries that they might lead to significant disability and chronic pain if suboptimally treated. Operative treatment is reserved for the displaced fractures. The primary aim of the herein study is to present the union time and rate, as well as the functional outcome of the surgically treated isolated lesser metatarsal shaft and neck fractures. The secondary aim is to present the related complications of each fixation method. METHODS: The electronic databases of Pubmed, Scopus, Embase and Cochrane libraries were searched from January 1990 to December 2020. PRISMA guidelines were used for data collection. We retrieved five articles including in total 154 patients, which were compatible to our inclusion criteria and they were used for this systematic review. RESULTS: A total of 75 patients were treated with percutaneous antegrade pinning resulting in AOFAS score: 96.4 ± 4.8 and time to heal 7.4 ± 1 weeks, 34 patients underwent ante/retrograde pinning resulting in AOFAS score: 95.2 ± 4.75 and time to heal 6.5 ± 1 weeks, and 45 patients underwent open reduction and internal fixation with plate and screws resulting in a time to union 10.9 ± 0.5 weeks. CONCLUSION: Our results demonstrate that K wire intramedullary nailing regardless of the specific technique (antegrade, retrograde, ante/retrograde) is associated with better outcomes compared to open reduction and internal fixation as it permits faster weight bearing and quicker rehabilitation. K-wire fixation is related to statistically significant shorter time for the fracture to heal, by approximately three weeks compared to open reduction and internal fixation. Future research should focus on studies directly comparing the different intramedullary K-wiring techniques and also K-wiring versus plate fixation.

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.

3D printing of implants for patient-specific acetabular fracture fixation: an experimental study.

PURPOSE: To test the effect of 3D printed implants, designed according to surgeon's individual plan, on the accuracy of reduction of an acetabular fracture model. METHODS: Seven identical standardized plastic bone models of an anterior column/posterior hemi-transverse acetabular fracture were used. A CT of one plastic fracture model was made. Using preoperative planning software, three surgeons independently planned the reduction and fixation procedure and designed implants and drill guides. The designed implants and guides were then 3D printed. Each surgeon first executed his plan using his 3D printed plates and guides on one fracture model and then performed another procedure on an identical model with standard implants and instrumentation. Displacement of the fragments at the weight-bearing fracture lines in the acetabulum was measured after fixation. Linear mixed effect models were used to evaluate the effect of different solutions to the same fracture pattern. RESULTS: Mean (SD) displacement of the fracture line between the ischium and stable fragment was 1.1 (0.9) mm for the standard implant and 0.8 (0.6) mm for the 3D printed implant, while the displacements of the fracture line between the stable fragment and anterior column were 0.6 (0.6) and 0.3 (0.3) for the standard and 3D printed methods, respectively (p < 0.001). Mean (SD) fracture line step-off at any fracture line for the standard implant was 1.2 (0.9) mm and 0.4 (0.4) mm for the 3D printed implant (p = 0.022). CONCLUSIONS: Patient-specific 3D printed plates and drill guides may facilitate retaining accurate reduction and fixation of select acetabular fracture patterns.

Fractures of the acetabulum: from yesterday to tomorrow.

PURPOSE: The aim of this article is to present history, state of the art, and future trends in the treatment of acetabular fractures. METHODS: Review of recent and historical literature. RESULTS: Acetabular fractures are difficult to treat. The first descriptions of this injury already appeared in ancient Greek history, but intensive development started in the second half of the twentieth century after Judet and Letournel's seminal work. Their classification is still the gold standard today. It is actually a pre-operative planning system and is used to determine the most appropriate surgical approach. The therapy of choice for dislocated fractures is open reduction and internal fixation. Recent modern techniques based on high-tech computerized planning systems and 3D printing have been successfully integrated into orthopaedic trauma practice. CONCLUSION: There is no ideal surgical approach for acetabulum fracture treatment, so new approaches have been developed in recent decades. The best outcome series have shown good or excellent results, between 70 and 80%.

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.

Acetabular loading in active abduction.

Operative fixation of fragments in acetabular fracture treatment is not strong enough to allow weight bearing before the bone is healed. In some patients, even passive or active nonweight-bearing exercises could lead to dislocation of fragments and posttraumatic osteoarthritis. Therefore, early rehabilitation should avoid loading the acetabulum in the regions of fracture lines. The aim of the paper is to estimate acetabular loading in nonweight-bearing upright, supine, and side-lying leg abduction. Three-dimensional mathematical models of the hip joint reaction force and the contact hip stress were used to simulate active exercises in different body positions. The absolute values of the hip joint reaction force and the peak contact hip stress are the highest in unsupported supine abduction (1.3 MPa) and in side-lying abduction (1.2 MPa), lower in upright abduction (0.5 MPa), and the lowest in supported supine abduction (0.2 MPa). All body positions the hip joint reaction force and the peak contact hip stress are the highest in the posterior-superior quadrant of acetabulum, followed by anterior-superior quadrant, posterior-inferior quadrant, and finally anterior-inferior quadrant. Spatial distribution of the average acetabular loading shows that early rehabilitation should be planned according to location of the fracture lines.

Preoperative planning in pelvic and acetabular surgery: the value of advanced computerised planning modules.

An experimental computer program for virtual operation of fractured pelvis and acetabulum based on real data of the fracture is presented. The program consists of two closely integrated tools, the 3D viewing tools and the surgeon simulation tools. Using 3D viewing tools the virtual model of a fractured pelvis is built. This procedure is performed by computer engineers. Data from CT of a real injury in DICOM format are used. With segmentation process each fracture segment becomes a separate object and is assigned a different colour. The virtual object is then transferred to the personal computer of the surgeon. Bone fragments can be moved and rotated in all three planes and reduction is performed. After reduction, fixation can be undertaken. The appropriate ostheosynthetic material can be chosen. Contouring of the plate is performed automatically to the reduced pelvis. The screws can be inserted into the plate or across the fracture. The direction and length of the screws is controlled by turning the pelvis or by making bones more transparent. The modeling of the plate in all three axes can be recorded as the exact length of the screws. There is also a simulation tool for intraoperative C-arm imaging in all directions. All the steps of the procedure are recorded and printed out. Postoperative matching of real operation and virtual procedure is also possible. We operated on 10 cases using virtual preoperative planning and found it very useful. The international study is still in progress. One case is presented demonstrating all the possibilities of the virtual planning and surgery. The presented computer program is an easily usable application which brings significant value and new opportunities in clinical practice (preoperative planning), teaching and research.