Objectives. External fixators are the traditional fixation method of choice for contaminated open fractures. However, patient acceptance is low due to the high profile and therefore physical burden of the constructs. An externalised locking compression plate is a low profile alternative. However, the biomechanical differences have not been assessed. The objective of this study was to evaluate the axial and torsional stiffness of the externalised titanium locking compression plate (ET-LCP), the externalised stainless steel locking compression plate (ESS-LCP) and the unilateral external fixator (UEF). Methods. A fracture gap model was created to simulate comminuted mid-shaft tibia fractures using synthetic composite bones. Fifteen constructs were stabilised with ET-LCP, ESS-LCP or UEF (five constructs each). The constructs were loaded under both axial and torsional directions to determine construct stiffness. Results. The mean axial stiffness was very similar for UEF (528 N/mm) and ESS-LCP (525 N/mm), while it was slightly lower for ET-LCP (469 N/mm). One-way analysis of variance (ANOVA) testing in all three groups demonstrated no significant difference (F(2,12) = 2.057, p = 0.171). There was a significant difference in mean torsional stiffness between the UEF (0.512 Nm/degree), the ESS-LCP (0.686 Nm/degree) and the ET-LCP (0.639 Nm/degree), as determined by one-way ANOVA (F(2,12) = 6.204, p = 0.014). A Tukey post hoc test revealed that the torsional stiffness of the ESS-LCP was statistically higher than that of the UEF by 0.174 Nm/degree (p = 0.013). No catastrophic failures were observed. Conclusion. Using the LCP as an external fixator may provide a viable and attractive alternative to the traditional UEF as its lower profile makes it more acceptable to patients, while not compromising on axial and torsional stiffness. Cite this article: B. F. H. Ang, J. Y. Chen, A. K. S. Yew, S. K. Chua, S. M. Chou, S. L. Chia, J. S. B. Koh, T. S. Howe. Externalised locking compression plate as an alternative to the unilateral external fixator: a biomechanical comparative study of axial and torsional stiffness. Bone Joint Res 2017;6:216–223. DOI: 10.1302/2046-3758.64.2000470

Aims. Despite limited clinical scientific backing, an additional trochanteric stabilizing plate (TSP) has been advocated when treating unstable trochanteric fractures with a sliding hip screw (SHS). We aimed to explore whether the TSP would result in less post operative fracture motion, compared to SHS alone. Methods. Overall, 31 patients with AO/OTA 31-A2 trochanteric fractures were randomized to either a SHS alone or a SHS with an additional TSP. To compare postoperative fracture motion, radiostereometric analysis (RSA) was performed before and after weightbearing, and then at four, eight, 12, 26, and 52 weeks. With the “after weightbearing” images as baseline, we calculated translations and rotations, including shortening and medialization of the femoral shaft. Results. Similar migration profiles were observed in all directions during the course of healing. At one year, eight patients in the SHS group and 12 patients in the TSP group were available for analysis, finding a clinically non-relevant, and statistically non-significant, difference in total translation of 1 mm (95% confidence interval -4.7 to 2.9) in favour of the TSP group. In line with the migration data, no significant differences in clinical outcomes were found. Conclusion. The TSP did not influence the course of healing or postoperative fracture motion compared to SHS alone. Based on our results, routine use of the TSP in AO/OTA 31-A2 trochanteric fractures cannot be recommended. The TSP has been shown, in biomechanical studies, to increase stability in sliding hip screw constructs in both unstable and intermediate stable trochanteric fractures, but the clinical evidence is limited. This study showed no advantage of the TSP in unstable (AO 31-A2) fractures in elderly patients when fracture movement was evaluated with radiostereometric analysis. Cite this article: Bone Jt Open 2024;5(1):37–45

Aims. The aim of this study was to determine the immediate post-fixation stability of a distal tibial fracture fixed with an intramedullary nail using a biomechanical model. This was used as a surrogate for immediate weight-bearing postoperatively. The goal was to help inform postoperative protocols. Methods. A biomechanical model of distal metaphyseal tibial fractures was created using a fourth-generation composite bone model. Three fracture patterns were tested: spiral, oblique, and multifragmented. Each fracture extended to within 4 cm to 5 cm of the plafond. The models were nearly-anatomically reduced and stabilized with an intramedullary nail and three distal locking screws. Cyclic loading was performed to simulate normal gait. Loading was completed in compression at 3,000 N at 1 Hz for a total of 70,000 cycles. Displacement (shortening, coronal and sagittal angulation) was measured at regular intervals. Results. The spiral and oblique fracture patterns withstood simulated weight-bearing with minimal displacement. The multifragmented model had early implant failure with breaking of the distal locking screws. The spiral fracture model shortened by a mean of 0.3 mm (SD 0.2), and developed a mean coronal angulation of 2.0° (SD 1.9°) and a mean sagittal angulation of 1.2° (SD 1.1°). On average, 88% of the shortening, 74% of the change in coronal alignment, and 75% of the change in sagittal alignment occurred in the first 2,500 cycles. No late acceleration of displacement was noted. The oblique fracture model shortened by a mean of 0.2 mm (SD 0.1) and developed a mean coronal angulation of 2.4° (SD 1.6°) and a mean sagittal angulation of 2.6° (SD 1.4°). On average, 44% of the shortening, 39% of the change in coronal alignment, and 79% of the change in sagittal alignment occurred in the first 2,500 cycles. No late acceleration of displacement was noted. Conclusion. For spiral and oblique fracture patterns, simulated weight-bearing resulted in a clinically acceptable degree of displacement. Most displacement occurred early in the test period, and the rate of displacement decreased over time. Based on this model, we offer evidence that early weight-bearing appears safe for well reduced oblique and spiral fractures, but not in multifragmented patterns that have poor bone contact. Cite this article: Bone Joint J 2021;103-B(2):294–298

Aims. This study aimed to analyze the correlation between transverse process (TP) fractures of the fourth (L4) and fifth (L5) lumbar vertebrae and biomechanical and haemodynamic stability in patients with a pelvic ring injury, since previous data are inconsistent. Patients and Methods. The study is a retrospective matched-pair analysis of patients with a pelvic fracture according to the modified Tile AO Müller and the Young and Burgess classification who presented to a level 1 trauma centre between January 2005 and December 2014. Results. A total of 728 patients with pelvic ring injuries were included, of whom 183 (25.1%) had a biomechanically unstable pelvic fracture. Of these patients, 84 (45.9%) had a fracture of a TP of L4 and/or L5. A total of 73 patients (13.4%) with a stable pelvic ring injury (p < 0.001) had a fracture of a TP. Patients with a fracture of a TP of L4 and/or L5 had a 5.5-fold risk (odds ratio (OR)) of having a biomechanically unstable pelvic injury. TP fractures (OR 1.6, p = 0.2) could not be confirmed as an independent predictor of haemodynamic instability. Conclusion. This is the first study that has demonstrated a positive correlation between a TP fracture of L4 and/or L5 and a biomechanically unstable pelvic ring injury. The presence of transverse process fractures of L4 and/or L5 indicates increased severity of pelvic injury and therefore can help in the planning of emergency treatment. Cite this article: Bone Joint J 2018;100-B:1214–19

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Posterior column plating through the single anterior approach reduces the morbidity in acetabular fractures that require stabilization of both the columns. The aim of this study is to assess the effectiveness of posterior column plating through the anterior intrapelvic approach (AIP) in the management of acetabular fractures.

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Proximal femur fractures treatment can involve anterograde nailing with a single or double cephalic screw. An undesirable failure for this fixation is screw cut-out. In a single-screw nail, a tip-apex distance (TAD) greater than 25 mm has been associated with an increased risk of cut-out. The aim of the study was to examine the role of TAD as a risk factor in a cephalic double-screw nail.

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The aims of this study were to identify means to quantify coronal plane displacement associated with distal radius fractures (DRFs), and to understand their relationship to radial inclination (RI).

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Distal third clavicle (DTC) fractures are increasing in incidence. Due to their instability and nonunion risk, they prove difficult to treat. Several different operative options for DTC fixation are reported but current evidence suggests variability in operative fixation. Given the lack of consensus, our objective was to determine the current epidemiological trends in DTC as well as their management within the UK.

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The aim of this study was to compare the functional and radiological outcomes and the complication rate after nail and plate fixation of unstable fractures of the ankle in elderly patients.

Aim. To quantify the micro-motion at the fracture gap in a tibial fracture model stabilised with an external fixator. Method. A surrogate model of a tibia and a cadaver leg were fractured and stabilised using a two-ring hexapod external fixator. They were tested initially under static loading and then subjected to vibration. Results. The overall stiffness of the cadaver leg was significantly higher than the surrogate model under static loading. This resulted in a significantly higher facture movement in the surrogate model. In the surrogate model there was no significant difference between the displacement applied via the vibrating platform and the fracture movement at the fracture gap. The fracture movement was however found to be statistically lower during vibration in the cadaver leg. Discussion. The significant difference in stiffness seen between the surrogate and cadaveric model is likely due to multiple factors such as the presence of soft tissues and fibula, including the biomechanical differences between the frame constructs. The fracture movement seen at 200N loading in the cadaveric leg was approximately 1mm which corresponds to partial weight bearing and a displacement shown to promote callus formation. During vibration however, the movements were far less suggesting that micromotion would be insufficient to promote healing. It may be proposed that soft tissues can alter the overall stiffness and fracture movement recorded in biomechanical studies investigating the effect of various devices or therapies

Introduction. Traumatized musculoskeletal tissue often exhibits prolonged time to healing, mostly due to low blood flow and innervation. Intermittent Pneumatic Compression (IPC) increases blood flow and decreases thromboembolic event after orthopedic surgery,[1] however little is known about healing effects.[2] We hypothesized that IPC could stimulate tissue repair: 1.) blood flow 2.) nerve ingrowth 3.) tissue proliferation and during immobilisation enhance 4.) biomechanical tissue properties. Methods. Study 1: In 104 male Sprague Dawley (SD) rats the right Achilles tendon was ruptured and the animals freely mobilized. Half the group received daily IPC-treatment, using a pump and cuff over the hindpaw that inflates/deflates cyclicly, 0–55mmHg (Biopress SystemTM, Flexcell Int.), and the other half received sham-treatment. Healing was assessed at 1,3,6 weeks by perfusion-analysis with laser doppler scanner (Perimed, Sweden), histology and biomechanical testing. Study 2: 48 male SD-rats were ruptured as above. Three groups of each 16 rats were either mobilized, immobilized or immobilized with IPC treatment. Immobilization was performed by plaster cast. Healing was assessed at 2 weeks with histology and biomechanical testing. Results. Study 1: At 3 and 6 weeks reperfusion increased by 21% and 23% (p< 0.05) after IPC-treatment, strengthened by the observation of elevated numbers of blood vessels and nerves. Fibroblast density was at all time points significantly increased in the IPC group. At three and six weeks the IPC treated tendons displayed an increased tissue organization confirmed by higher collagen I/III ratio in the IPC group. No differences (p = 0.10) were found regarding biomechanical strength. Study 2: Compared to mobilization, immobilization caused a downregulation (p<0.05) of all biomechanical and histological parameters, eg. maximum force decreased 80% and collagen III occurrence by 83%. However when immobilization was combined with IPC biomechanical and histological healing increased significantly compared to pure immobilization, eg. maximum force increased 63% and collagen III occurrence by 150%. Conclusion. This study demonstrated that IPC treatment can counteract biomechanical and morphological deficits caused by immobilization by enhancing proliferative soft tissue repair. Thus, IPC promotes tissue repair by stimulating tissue perfusion and nerve ingrowth as well as accelerating both fibroblast proliferation and collagen organization

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Due to the recent rapid expansion of scooter sharing companies, there has been a dramatic increase in the number of electric scooter (e-scooter) injuries. Our purpose was to conduct a systematic review to characterize the demographic characteristics, most common injuries, and management of patients injured from electric scooters.

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Our objective was to conduct a systematic review and meta-analysis, to establish whether differences arise in clinical outcomes between autologous and synthetic bone grafts in the operative management of tibial plateau fractures.

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Postoperative malalignment of the femur is one of the main complications in distal femur fractures. Few papers have investigated the impact of intraoperative malalignment on postoperative function and bone healing outcomes. The aim of this study was to investigate how intraoperative fracture malalignment affects postoperative bone healing and functional outcomes.

Aims. The aim of this paper is to review the evidence relating to the anatomy of the proximal femur, the geometry of the fracture and the characteristics of implants and methods of fixation of intertrochanteric fractures of the hip. Materials and Methods. Relevant papers were identified from appropriate clinical databases and a narrative review was undertaken. Results. Stable, unstable, and subtrochanteric intertrochanteric fractures vary widely in their anatomical and biomechanical characteristics, as do the implants used for their fixation. The optimal choice of implant addresses the stability of the fracture and affects the outcome. Conclusion. The treatment of intertrochanteric fractures of the hip has evolved along with changes in the design of the implants used to fix them, but there remains conflicting evidence to guide the choice of implant. We advocate fixation of 31A1 fractures with a sliding hip screw and all others with an intramedullary device. Cite this article: Bone Joint J 2017;99-B:128–33

Introduction. Locking compression plate (LCP) fixation is an established method of treatment of distal third tibial fractures. No biomechanical data exists in the literature regarding their use. Additionally no data exists on the biomechanical advantage of locking screw fixation over non-locking screw fixation for these fractures. In this study the axial and torsional stiffness, axial load to failure and fatigue performance of a 3.5 mm LCP medial distal tibia Synthes plate was evaluated for the stabilisation of distal third tibial fractures. Additionally the performance of the plate in uni and bicortical locked mode as well as non-locked mode was evaluated. Methods. A standardized oblique fracture pattern was created in the tibial metaphysis of 3rd generation composite tibias, 40 mm from the distal end of the tibia (AO 43-A2.3). A 10mm fracture gap was used to model a comminuted metaphyseal fracture. A 3.5 mm medial distal tibia LCP was applied with bi or unicortical locking or bicortical non-locking screws to 5 tibias respectively. All the bio-mechanical tests were performed on a Bose 3510 Electroforce material testing machine. A ramp to load, loading profile was used to determine the static axial and torsional performance of the construct. Fatigue testing simulated a 6 week gradual weight bearing régime with the load increasing every two weeks by 400N until either 250,000 cycles were completed or the construct failed. Results. The non-locked plate demonstrated a significantly higher load to failure than both the bicortical and unicortical locked plates, 683N vs. 575N vs. 483N respectively(p<0.01). The non locked plate also demonstrated significantly higher mean axial stiffness than the bicortical locked plate and unicortical locked plate 632±13 N/mm, 337±12N/mm and 266±6 N/mm respectively (p <0.01). The non locked plate demonstrated the highest torsional stiffness followed by the bi and unicortical locking plates 1.16 ±.08 Nmm vs. 0.79 ± .06 Nmm vs.0.40 ± 0.02 Nmm respectively (p < 0.01). The non locked plate demonstrated higher endurance than the bi and unicortical locking plates over a 6 week simulated fatigue cycle with 1.75mm, 2.10mm and 2.3mm residual displacement at 1600N respectively (p < 0.01). Discussion. This is the first study that has examined the biomechanical properties of the LCP when used for distal third tibial fractures. A review of the literature suggests LCPs outperform dynamic compression plates in osteoporotic bone but demonstrates no clear biomechanical advantage in using a locking construct in non-osteoporotic bone. In our study the non locked construct outperformed the locked constructs in all parameters assessed. We conclude there is no advantage in using a locking construct for distal third tibial fractures in good quality bone

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The modified Radiological Union Scale for Tibia (mRUST) fractures score was developed in order to assess progress to union and define a numerical assessment of fracture healing of metadiaphyseal fractures. This score has been shown to be valuable in predicting radiological union; however, there is no information on the sensitivity, specificity, and accuracy of this index for various cut-off scores. The aim of this study is to evaluate sensitivity, specificity, accuracy, and cut-off points of the mRUST score for the diagnosis of metadiaphyseal fractures healing.

INTRODUCTION. Patellar tendon (PT) autograft is an excellent choice repairing anterior cruciate ligament (ACL) ruptures. Published studies testing the biomechanical characteristics after plasty usually refer to grafts with 10mm wide. The thickness of PT and geometry of the patella have been overlooked. The purpose of this study was to understand the geometry of PT and patella in our population, regarding their use in Bone - Patellar Tendon - Bone (BTB) technique, in order to evaluate their biomechanical efficiency and study their relationship with anthropometric parameters. MATERIAL. 100 individuals (50/50) who underwent knee MRI (3-Tesla). Ages between 18–65years. METHODS. Retrospective study. Standardized protocol for measuring the PT and patella based in MRI images. Interview to obtain personal data. Statistical analysis using SPSS®. RESULTS. Sample (mean ±SD): age 41 ±14years, weight 73 ±12kg, height 167 ±10cm, BMI 26,04 ±4,13; length PT/patella −41,3 ±6,1mm/29,6 ±4,2 mm, width PT/patella −25,3 ±3,2mm/43,4 ±4,14mm; thickness PT −3,79 ±1,01mm/22,8 ±2,2mm; Men have thicker and wider patella and PT than women (p<0.001). The patella is also longer in males (p<0.001). There is statistical significant relationship between weight and height to width, thickness and length of PT and patella (p<0.01). Body Mass Index (BMI) doesn't have statistical correlation with geometry of the PT and patella. DISCUSSION. The PT remains as an excellent option in ACL repair. The anatomy and quality of the graft are essential to achieving good functional results. The choice of middle third tendon to the BTB plasty does not always correspond to the 10mm width, as used in most biomechanical tests. Also patellar integrity can be at risk (when collecting the bone block) if patella geometry is not considered. To our knowledge, there is only one similar study in literature, preformed in Asian individuals. CONCLUSION. Preoperatively accessing the geometry of Patella and PT can be crucial in obtaining efficient grafts and decreasing morbidity over the extensor mechanism

Introduction. It was the purpose to evaluate the biomechanical changes that occur after optimal and non-optimal component placement of a hip resurfacing (SRA) by using a subject specific musculoskeletal model based on CT-scan data. Materials and Methods. Nineteen hips from 11 cadavers were resurfaced with a BHR using a femoral navigation system. CT images were acquired before and after surgery. Grey-value segmentation in Mimics produced contours representing the bone geometry and identifying the outlines of the 3 parts of the gluteus medius. The anatomical changes induced by the procedure were characterised by the translation of the hip joint center (HJCR) with respect to the pelvic and femoral bone. The contact forces during normal gait with ‘optimal’ component placement were calculated for a cement mantle of 3 mm, a socket inclination of 45° and anteversion of 15°. The biomechanical effect of ‘non-optimal placement’ was simulated by varying the positioning of the components. Results. There was a significant (p<0.01) shortening of the muscle length with the ‘optimal’ component placement for all parts of the gluteus medius with the largest shortening of the posterior part by 6mm. This was caused by a significant shortening of the femoral offset by 2.3mm (p<0.01). Because of a significant (p<0.01) medialisation of the HJCR by 4 mm, there was no significant increase in contact force. The hip joint contact forces increased by 0.5% per mm HJCR displacement. Each millimeter of cranial and lateral displacement of the femoral HJCR increased the contact force by 0.5% and 1%, respectively. The contact stresses changed significantly by 0.8% and 0.2% per degree of socket inclination and anteversion. The contact force increased 1% per mm lateral displacement of the acetabular HJCR. Discussion. Optimal placement of the SRA components did not completely restore the biomechanics of the native hip joint. The contact forces were not increased due to the compensatory effect of the medialisation of the acetabular HJCR. This suggests that reaming to the acetabular floor should be conducted in SRA. Femoral component displacement in the cranial and lateral direction significantly increased the hip joint loading. Errors of socket placement in the coronal and sagital plane significantly increased the contact stresses. Accumulative errors of both component displacements could lead to increased contact stresses of 18% to 23% with socket inclinations of 50° and 55°. Surgeons should reconsider continuing the SRA procedure if a neck length loss and lateralisation of the HCJR by >5 mm is anticipated as this would increase the contact stresses by >12%

Introduction. The degeneration of the adjacent segment in lumbar spine with spondylodesis is well known, though the exact incidence and the mechanism is not clear. Several implants with semi rigid or dynamic behavior are available to reduce the biomechanical loads and to prevent an adjacent segment disease (ASD). Randomized controlled trials are not published. We investigated the biomechanical influence of dynamic and semi rigid implants on the adjacent segment in cadaver lumbar spine with monosegmental fusion (MF). Materials and Methods. 14 fresh cadaver lumbar spines were prepared; capsules and ligaments were kept intact. Pure rotanional moments of ±7.5 Nm were applied with a Zwick 1456 universal testing machine without preload in lateral bending and flexion/extension. The intradiscal pressure (IDP) and the range of motion (ROM) were measured in the segments L2/3 and L3/4 in following situations: in the native spine, monosegmental fusion L4/5 (MF), MF with dynamic rod to L3/4 (Dynabolt), MF with interspinous implant L3/4 (Coflex), and semi rigid fusion with PEEK rod (CD Horizon Legacy) L3-L5. Results. Under flexion load all implants reduced the IDP of segment L2/L3, whereas the IDP in the segment L3/4 was increased using interspinous implants in comparison to the other groups. The IDP was reduced in extension in both segments for all semi rigid or dynamic implants. Compared under extension to the native spine the MF had no influence on the IDP of the adjacent disc. The rod instrumentation (Dynabolt, PEEK rod) lead to a decreased IDP in lateral bending tests. The ROM in L3 was reduced in all groups compared to the native spine. The dynamic and semi rigid stabilization in the segment L3/4 limited the ROM more than the MF. Discussion. The MF reduced the ROM in all directions, whereas the IDP of the adjacent segment remained unaffected. The support of the adjacent segment by semi rigid and dynamic implants decreased the IDP of both segments in extension mainly. This fact is an agreement with other studies. Compared to our data, no significant effect on the adjacent levels was observed. Interestingly, in our study, the IDP of the adjacent segment is unaffected by MF. The biomechanical influence in the view of an ASD could be comprehended, but is not completely clear. The fact of persistent IDP in the adjacent segment suggests that MF has a lower effect on the adjacent segment degeneration as presumed. Biomechanical studies with human cadaver lumbar spines are limited and depend on age and degenerative situation. The effect on supporting implants on adjacent segment disease in lumbar spine surgery has to be investigated in clinical long term studies