Locked plating of distal femur fractures leads to inconsistent and asymmetric callus formation

Advances in Dynamization of Plate Fixation to Promote Natural Bone Healing

The controlled dynamization of fractures can promote natural fracture healing by callus formation, while overly rigid fixation can suppress healing. The advent of locked plating technology enabled new strategies for the controlled dynamization of fractures, such as far cortical locking (FCL) screws or active plates with elastically suspended screw holes. However, these strategies did not allow for the use of non-locking screws, which are typically used to reduce bone fragments to the plate. This study documents the first in vivo study on the healing of ovine tibia osteotomies stabilized with an advanced active plate (AAP). This AAP allowed plate application using any combination of locking and non-locking screws to support a wide range of plate application techniques. At week 9 post-surgery, tibiae were harvested and tested in torsion to failure to assess the healing strength. The five tibiae stabilized with an AAP regained 54% of their native strength and failed by spiral fracture through a screw hole, which did not involve the healed osteotomy. In comparison, tibiae stabilized with a standard locking plate recovered 17% of their strength and sustained failure through the osteotomy. These results further support the stimulatory effect of controlled motion on fracture healing. As such, the controlled dynamization of locked plating constructs may hold the potential to reduce healing complications and may shorten the time to return to function. Integrating controlled dynamization into fracture plates that support a standard fixation technique may facilitate the clinical adoption of dynamic plating.

Risk Factors of Failure in 228 Periprosthetic Distal Femur Fractures: A Multicenter Study

OBJECTIVES

To identify risk factors of reoperation to promote union or to address deep surgical-site infection (DSSI) in periprosthetic distal femur fractures treated with lateral distal femoral locking plates (LDFLPs).

METHODS

DESIGN

Multicenter retrospective cohort study.

SETTING

Ten level-I trauma centers.

PATIENT SELECTION CRITERIA

Patients with Orthopaedic Trauma Association/Association of Osteosynthesis (OTA/AO) 33A or 33C periprosthetic distal femur fractures who underwent surgical fixation between January 2012 and December 2019 exclusively using LDFLPs were eligible for inclusion. Patients with pathologic fractures or with follow-up less than 3 months without an outcome event (unplanned reoperation to promote union or for deep surgical infection) before this time point were excluded. Fracture fixation constructs used medial plates, intramedullary nails, or hybrid fixation constructs were excluded from analysis.

OUTCOME MEASURES AND COMPARISONS

To examine the influence of patient demographics, injury characteristics, and features of the fracture fixation construct on the occurrence of unplanned reoperation to promote union or to address a DSSI.

RESULTS

There was an 8.3% rate (19/228) of unplanned reoperation to promote union. Predictive factors for the need for reoperation to promote union included increasing body mass index (odds ratio [OR] = 1.09; 95% confidence interval [CI]: 1.02-1.16; P = 0.01), increasing number of screws in the distal fracture segment (OR = 1.73; 95% CI: 1.06-2.95; P = 0.03), and decreasing proportion of proximal segment screws that are locking (OR = 0.17; 95% CI: 0.03-0.70; P = 0.02) There was a 4.8% rate (11/228) of reoperation to address DSSI. There were no statistically significant predictive factors identified as risk factors of the need for reoperation to address DSSI ( P > 0.05).

CONCLUSIONS

8.3% of periprosthetic distal femur fractures treated at 10 centers with LDFLPs underwent unplanned reoperation to promote union. Increasing patient body mass index and increasing number of screws in the distal fracture segment were found to be predictive factors, whereas increased locking screws in the proximal segment were found to be protective. 4.8% of patients in this cohort underwent reoperation to address DSSI.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

Far cortical locking constructs for fixation of distal femur fractures in an Asian population: A prospective observational study

BACKGROUND

The stiffness of locked plates suppresses healing process, prompting the introduction of far cortical locking to address this issue. This study aimed to demonstrate the clinical efficacy of far cortical locking constructs in treating distal femoral fractures in an Asian population.

METHODS

This multicenter prospective observational study was conducted at four university hospitals between February 2018 and February 2021. Demographic data, the presence of metaphyseal comminution, and surgical fixation details were recorded. Clinical outcomes, including single-leg standing, EQ-5D, and EQ-VAS scores, and radiologic outcomes, including the RUST score of each cortex, were evaluated and compared according to the presence of metaphyseal comminution.

RESULTS

There were 37 patients (14 men and 23 women) with a mean age of 67.3 ± 11.8 years. Twenty-two patients had metaphyseal comminution (59%), and 15 presented simple fractures in metaphyseal areas. Four patients (13%) could stand on one leg >10s at 6 weeks, and 24 patients (92%) at 1 year. EQ-5D increased from 0.022 ± 0.388 to 0.692 ± 0.347, and the mean EQ-VAS 51.1 ± 13.1 to 74.1 ± 24.1 between discharge (n = 37) and post-operative 1 year (n = 33), respectively. RUST score presented increment for time, from 6.2 ± 1.8 at 6 week to 11.6 ± 1.1 at 1 year. Radiological healing demonstrated rapid increase from week 6 (16/28, 43%) to month 3 (27/31, 87%), with no obvious increase was observed in 6 months (23/26, 89%) or 12 months (25/28, 89%). Simple metaphyseal fractures presented significantly higher RUST scores at 6 weeks and 3 months, but there was no difference in RUST scores at 6 months or 1 year according to metaphyseal comminution.

CONCLUSIONS

Plate constructs with far cortical locking screws provided safe and effective fixation for distal femoral fractures, with consistent radiological and clinical results, regardless of metaphyseal comminution.

Severity of Complications after Locking Plate Osteosynthesis in Distal Femur Fractures

Background: Locked plating for distal femur fractures is widely recommended and used. We systematically reviewed clinical studies assessing the benefits and harms of fracture fixation with locked plates in AO/OTA Type 32 and 33 femur fractures. Methods: A comprehensive literature search of PubMed, Embase, Cinahl, Web of Science, and the Cochrane Database was performed. The studies included randomized and non-randomized clinical trials, observational studies, and case series involving patients with distal femur fractures. Studies of other fracture patterns, studies conducted on children, pathological fractures, cadaveric studies, animal models, and those with non-clinical study designs were excluded. Results: 53 studies with 1788 patients were found to satisfy the inclusion and exclusion criteria. The most common harms were nonunion (14.8%), malunion (13%), fixation failure (5.3%), infection (3.7%), and symptomatic implant (3.1%). Time to full weight-bearing ranged from 5 to 24 weeks, averaging 12.3 weeks. The average duration of follow-up was 18.18 months, ranging from 0.5 to 108 months. Surgical time ranged between 40 and 540 min, with an average of 141 min. The length of stay in days was 12.7, ranging from 1 to 61. The average plate length was ten holes, ranging from 5 to 20 holes. Conclusion: This review aimed to systematically synthesize the available evidence on the risk associated with locked plating osteosynthesis in distal femur fractures. Nonunion is the most common harm and is the primary cause of reoperation. The overall combined risk of a major and critical complication (i.e., requiring reoperation) is approximately 20%.

Biomechanical analysis of combi-hole locking compression plate during fracture healing: A numerical study of screw configuration

Locking compression plates (LCPs) have become a widely used option for treating femur bone fractures. However, the optimal screw configuration with combi-holes remains a subject of debate. The study aims to create a time-dependent finite element (FE) model to assess the impacts of different screw configurations on LCP fixation stiffness and healing efficiency across four healing stages during a complete fracture healing process. To simulate the healing process, we integrated a time-dependent callus formation mechanism into a FE model of the LCP with combi-holes. Three screw configuration parameters, namely working length, screw number, and screw position, were investigated. Increasing the working length negatively affected axial stiffness and healing efficiency (p < 0.001), while screw number or position had no significant impact (p > 0.01). The time-dependent model displayed a moderate correlation with the conventional time-independent model for axial stiffness and healing efficiency (ρ ≥ 0.733, p ≤ 0.025). The highest healing efficiency (95.2%) was observed in screw configuration C125 during the 4-8-week period. The results provide insights into managing fractures using LCPs with combi-holes over an extended duration. Under axial compressive loading conditions, the use of the C125 screw configuration can enhance callus formation during the 4-12-week period for transverse fractures. When employing the C12345 configuration, it becomes crucial to avoid overconstraint during the 4-8-week period.

Plate fixation optimization for distal femoral fractures with segmental bone loss: Defining the preferred screw distribution using finite element analysis

OBJECTIVES

Distal femur fractures can exhibit extensive comminution, and open fractures may result in bone loss. These injuries are under high mechanical demands when stabilized with a lateral locked plate (LLP), and are at risk of non-union or implant failure. This study investigates the optimal LLP screw configuration for distal femur fractures with a large metadiaphyseal gap of 5 cm.

METHODS

A finite element (FE) model, validated against experimentally measured strains and displacement, evaluated pull-out forces and stress concentration on typical implants under clinical conditions corresponding with the 10 % point during the stance phase of the gait cycle.

RESULTS

Maximum stress was up to 83 % less when the ratio (Cp) between the proximal screw-distribution-length and the distance of the first screw to the fracture was less than 0.2; maximum pull-out force was 99 % less when this ratio was higher than 0.4.

CONCLUSIONS

Screw configuration based on either normal or osteopenic bone quality plays an important role in determining the risk of construct failure for a major (50 mm) distal femoral metadiaphyseal segmental defect. This study provides valuable information when planning definitive fixation for distal femur fractures with extensive comminution or segmental bone defects, to mitigate the risk of implant failure and subsequent nonunion.

Retrograde Intramedullary Nailing Versus Locked Plating for Extreme Distal Periprosthetic Femur Fractures: A Multicenter Retrospective Cohort Study

OBJECTIVES

To compare clinical and radiographic outcomes after retrograde intramedullary nailing (rIMN) versus locked plating (LP) of "extreme distal" periprosthetic femur fractures, defined as those that contact or extend distal to the anterior flange.

METHODS

DESIGN

Retrospective review.

SETTING

Eight academic level I trauma centers.

PATIENT SELECTION CRITERIA

Adult patients with periprosthetic distal femur fractures at or distal to the anterior flange (OTA/AO 33B-C[VB1]) treated with rIMN or LP.

OUTCOME MEASURES AND COMPARISONS

The primary outcome was reoperation to promote healing or to treat infection (reoperation for elective removal of symptomatic hardware was excluded from this analysis). Secondary outcomes included nonunion, delayed union, fixation failure, infection, overall reoperation rate, distal femoral alignment, and ambulatory status at final follow-up. Outcomes were compared between patients treated with rIMN or LP.

RESULTS

Seventy-one patients treated with rIMN and 224 patients treated with LP were included. The rIMN group had fewer points of fixation in the distal segment (rIMN: 3.5 ± 1.1 vs. LP: 6.0 ± 1.1, P < 0.001) and more patients who were allowed to weight-bear as tolerated immediately postoperatively (rIMN: 45%; LP: 9%, P < 0.01). Reoperation to promote union and/or treat infection was 8% in the rIMN group and 16% in the LP group ( P = 0.122). There were no significant differences in nonunion ( P > 0.999), delayed union ( P = 0.079), fixation failure ( P > 0.999), infection ( P = 0.084), or overall reoperation rate ( P > 0.999). Significantly more patients in the rIMN group were ambulatory without assistive devices at final follow-up (rIMN: 35%, LP: 18%, P = 0.008).

CONCLUSIONS

rIMN of extreme distal periprosthetic femur fractures has similar complication rates compared with LP, with a possible advantage of earlier return to weight-bearing. Surgeons can consider this treatment strategy in all fractures with stable implants and amenable prosthesis geometry, even extreme distal fractures.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Do working length and proximal screw density influence the velocity of callus formation in distal tibia fractures treated with a medial bridge plate?

INTRODUCTION

Aim of our study was to evaluate the influence of working length and screw density on callus formation in distal tibial fractures fixed with a medial bridge plate.

MATERIALS AND METHODS

42 distal tibia fractures treated with a bridge plate were analyzed. Minimum follow-up was 12 months. mRUST score (modified Radiographic Union Scale for Tibial fractures) was used to assess callus formation. Working length and screw density were  measured from post-operative radiographs.

RESULTS

39 (92.9%) fractures healed uneventfully. 32 (76.19%) patients showed signs of early callus formation 3 months post-surgery. In these patients a lower screw density was used compared to patients who didn't show early callus (33.4 vs. 26.6; p = 0.04). No differences was noticed in working length.

CONCLUSION

Bridge plate osteosynthesis is a good treatment option in distal tibia fractures. In our series increasing the working length was not associated with a faster callus formation in distal tibia fractures. Conversely, a lower screw density proximally to the fracture site was associated to a faster callus growth.

What is the stable internal fixation for the unstable and osteoporotic supracondylar femoral fractures: a finite element analysis

BACKGROUND

Osteoporotic supracondylar femoral fractures (OSFF) have historically been managed by the lateral anatomical locking plate with reasonable success. However, for some kinds of unstable and osteoporotic supracondylar femoral fractures (UOSFF), especially with bone defects, unilateral locking plate (ULLP) fixation failed or resulted in implant breakage. This paper is going to explore what is the stable internal fixation for UOSFF by adding the bilateral locking plate (BLLP) fixation.

METHODS

OSFF models were divided into two groups according to the fracture line type, which would be further subdivided according to their angle of fracture line, presence of bone defect, location, and degree of bone defect. Thereafter, kinds of locking plate fixation were constructed. A 2010-N load was applied to the femoral head, and a 1086-N load was applied to the greater trochanter. In this condition, the maximum von Mises stress distribution of models were investigated.

RESULTS

Firstly, it was obviously found that the stress concentration in the BLLP group was more dispersed than that in the ULLP group. Secondly, according to the fracture line analysis, the stress value of fracture line type in "\" model group was higher than that of "/" model group. Moreover, with the increase in fracture line angle, the stress value of the model increased. Thirdly, from the bone defect analysis, the stress value of the medial bone defect (MBD) model group was higher than that of the lateral bone defect (LBD) model group. And as the degree of bone defect increased, the stress value increased gradually in the model group.

CONCLUSION

In the following four cases, lateral unilateral locking plate fixation cannot effectively stabilize the fracture end, and double locking plate internal fixation is a necessary choice. First, when the angle of the fracture line is large (30, 45). Second, when the fracture line type is "/." Third, when the bone defect is large. Fourth, when the bone defect is medial.

Bridge Plate Fixation of Distal Femur Fractures: Defining Deficient Radiographic Callus Formation and Its Associations

OBJECTIVE

To determine whether deficient early callus formation can be defined objectively based on the association with an eventual nonunion and specific patient, injury, and treatment factors.

METHODS

Final healing outcomes were documented for 160 distal femur fractures treated with locked bridge plate fixation. Radiographic callus was measured on postoperative radiographs until union or nonunion had been declared by the treating surgeon. Deficient callus was defined at 6 and 12 weeks based on associations with eventual nonunion through receiver-operator characteristic analysis. A previously described computational model estimated fracture site motion based on the construct used. Univariable and multivariable analyses then examined the association of patient, injury, and treatment factors with deficient callus formation.

RESULTS

There were 26 nonunions. The medial callus area at 6 weeks <24.8 mm 2 was associated with nonunion (12 of 39, 30.8%) versus (12 of 109, 11.0%), P = 0.010. This association strengthened at 12 weeks with medial callus area <44.2 mm 2 more closely associated with nonunion (13 of 28, 46.4%) versus (11 of 120, 9.2%), P <0.001. Multivariable logistic regression analysis found limited initial longitudinal motion (OR 2.713 (1.12-6.60), P = 0.028)) and Charlson Comorbidity Index (1.362 (1.11-1.67), P = 0.003) were independently associated with deficient callus at 12 weeks. Open fracture, mechanism of injury, smoking, diabetes, plate material, bridge span, and shear were not significantly associated with deficient callus.

CONCLUSION

Deficient callus at 6 and 12 weeks is associated with eventual nonunion, and such assessments may aid future research into distal femur fracture healing. Deficient callus formation was independently associated with limited initial longitudinal fracture site motion derived through computational modeling of the surgical construct but not more routinely discussed parameters such as plate material and bridge span. Given this, improved methods of in vivo assessment of fracture site motion are necessary to further our ability to optimize the mechanical environment for healing.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Depth camera-based model for studying the effects of muscle loading on distal radius fracture healing

BACKGROUND

Distal radius fractures (DRFs) treated with volar locking plates (VLPs) allows early rehabilitation exercises favourable to fracture recovery. However, the role of rehabilitation exercises induced muscle forces on the biomechanical microenvironment at the fracture site remains to be fully explored. The purpose of this study is to investigate the effects of muscle forces on DRF healing by developing a depth camera-based fracture healing model.

METHOD

First, the rehabilitation-related hand motions were captured by a depth camera system. A macro-musculoskeletal model is then developed to analyse the data captured by the system for estimating hand muscle and joint reaction forces which are used as inputs for our previously developed DRF model to predict the tissue differentiation patterns at the fracture site. Finally, the effect of different wrist motions (e.g., from 60° of extension to 60° of flexion) on the DRF healing outcomes will be studied.

RESULTS

Muscle and joint reaction forces in hands which are highly dependent on hand motions could significantly affect DRF healing through imposed compressive and bending forces at the fracture site. There is an optimal range of wrist motion (i.e., between 40° of extension and 40° of flexion) which could promote mechanical stimuli governed healing while mitigating the risk of bony non-union due to excessive movement at the fracture site.

CONCLUSION

The developed depth camera-based fracture healing model can accurately predict the influence of muscle loading induced by rehabilitation exercises in distal radius fracture healing outcomes. The outcomes from this study could potentially assist osteopathic surgeons in designing effective post-operative rehabilitation strategies for DRF patients.

Prediction of fracture nonunion leading to secondary surgery in patients with distal femur fractures

Aims

Several previously identified patient-, injury-, and treatment-related factors are associated with the development of nonunion in distal femur fractures. However, the predictive value of these factors is not well defined. We aimed to assess the predictive ability of previously identified risk factors in the development of nonunion leading to secondary surgery in distal femur fractures.

Methods

We conducted a retrospective cohort study of adult patients with traumatic distal femur fracture treated with lateral locking plate between 2009 and 2018. The patients who underwent secondary surgery due to fracture healing problem or plate failure were considered having nonunion. Background knowledge of risk factors of distal femur fracture nonunion based on previous literature was used to form an initial set of variables. A logistic regression model was used with previously identified patient- and injury-related variables (age, sex, BMI, diabetes, smoking, periprosthetic fracture, open fracture, trauma energy, fracture zone length, fracture comminution, medial side comminution) in the first analysis and with treatment-related variables (different surgeon-controlled factors, e.g. plate length, screw placement, and proximal fixation) in the second analysis to predict the nonunion leading to secondary surgery in distal femur fractures.

Results

We were able to include 299 fractures in 291 patients. Altogether, 31/299 fractures (10%) developed nonunion. In the first analysis, pseudo-R2 was 0.27 and area under the receiver operating characteristic curve (AUC) was 0.81. BMI was the most important variable in the prediction. In the second analysis, pseudo-R2 was 0.06 and AUC was 0.67. Plate length was the most important variable in the prediction.

Conclusion

The model including patient- and injury-related factors had moderate fit and predictive ability in the prediction of distal femur fracture nonunion leading to secondary surgery. BMI was the most important variable in prediction of nonunion. Surgeon-controlled factors had a minor role in prediction of nonunion.

Medial augmentation plating of aseptic distal femoral nonunions

BACKGROUND

Distal femur nonunions are well-recognized contributors to persistent functional disability, with limited data regarding their treatment options. In the current study, we asked whether additional medial augmentation plating is a feasible treatment option for patients with aseptic distal femoral nonunion and intact lateral implants.

METHODS

We conducted a single-center, retrospective study including 20 patients treated for aseptic distal femoral nonunion between 2002 and 2017. The treatment procedure included a medial approach to the distal femur, debridement of the nonunion site, bone grafting and medial augmentation plating utilizing a large-fragment titanium plate. Outcome measures were bone-related and functional results, measured by the Hospital for Special Surgery Knee Rating Scale (HSS) and the German Short Musculoskeletal Function Assessment questionnaire (SMFA-D).

RESULTS

Eighteen of 20 nonunions showed osseous healing at 8.16 ± 5.23 (range: 3-21) months after augmentation plating. Regarding functional results, the mean HSS score was 74.17 ± 11.12 (range: 57-87). The mean SMFA-D functional index was 47.38 ± 16.78 (range 25.74-71.32) at the last follow-up. Index procedure-associated complications included two cases of persistent nonunion and one case of infection.

CONCLUSIONS

According to the assessed outcome measures, augmentation plating is a feasible treatment option, with a high proportion of patients achieving bony union and good functional outcomes and a few patients experiencing complications.

Biomechanical design optimization of distal femur locked plates: A review

Clinical findings, manufacturer instructions, and surgeon's preferences often dictate the implantation of distal femur locked plates (DFLPs), but healing problems and implant failures still persist. Also, most biomechanical researchers compare a particular DFLP configuration to implants like plates and nails. However, this begs the question: Is this specific DFLP configuration biomechanically optimal to encourage early callus formation, reduce bone and implant failure, and minimize bone "stress shielding"? Consequently, it is crucial to optimize, or characterize, the biomechanical performance (stiffness, strength, fracture micro-motion, bone stress, plate stress) of DFLPs influenced by plate variables (geometry, position, material) and screw variables (distribution, size, number, angle, material). Thus, this article reviews 20 years of biomechanical design optimization studies on DFLPs. As such, Google Scholar and PubMed websites were searched for articles in English published since 2000 using the terms "distal femur plates" or "supracondylar femur plates" plus "biomechanics/biomechanical" and "locked/locking," followed by searching article reference lists. Key numerical outcomes and common trends were identified, such as: (a) plate cross-sectional area moment of inertia can be enlarged to lower plate stress at the fracture; (b) plate material has a larger influence on plate stress than plate thickness, buttress screws, and inserts for empty plate holes; (c) screw distribution has a major influence on fracture micro-motion, etc. Recommendations for future work and clinical implications are then provided, such as: (a) simultaneously optimizing fracture micro-motion for early healing, reducing bone and implant stresses to prevent re-injury, lowering "stress shielding" to avoid bone resorption, and ensuring adequate fatigue life; (b) examining alternate non-metallic materials for plates and screws; (c) assessing the influence of condylar screw number, distribution, and angulation, etc. This information can benefit biomedical engineers in designing or evaluating DFLPs, as well as orthopedic surgeons in choosing the best DFLPs for their patients.

Treatment of comminuted metaphyseal distal femoral fractures with a micromotion-balancing osteosynthesis: an animal study

BACKGROUND

Locking plates are commonly used in the treatment of comminuted metaphyseal distal femoral fractures. However, locking plates form a strong structure and promote asymmetrical callus formation, which is not conducive for rapid fracture healing and may increase fracture risk. To overcome this, we designed a micromotion-balancing fixation system based on locking plates.

METHODS

Six healthy pigs (Bama miniature pigs) were used to establish a model of bilateral comminuted distal femoral fracture (AO/ASIF: 33-C2). Standard drilling was performed on one of each pig's hind limbs (control group), whereas eccentric drilling was performed on the other hind limb (experimental group). Both femurs were fixed with a 3-hole locking compression plate using 5-mm-diameter screws. At 12 postoperative weeks, all pigs were euthanized and the femurs with compression plates were radiographically examined. The level of fracture healing and loosening/internal fixation failure were recorded. Bone mineral density, number of trabeculae, trabecular morphology, and calcification precipitations were assessed.

RESULTS

All pigs survived, and the fractures healed. No complications related to fracture healing, such as infection and internal fixation failure, were noted. The bone mineral density of the near and far cortical calli, number of the near and far cortical callus trabeculae, and difference in bone mineral density between the near and far cortical calli in the experimental group were significantly higher than those in the control group (p < 0.01). However, the difference in the number of trabeculae between the near and far cortical calli was significantly lower in the experimental group than in the control group (p < 0.01).

CONCLUSION

This newly designed system provides stable fixation for comminuted distal femoral fracture, increases the overall strain at the fracture site, and balances the strains at the near and far cortices to achieve uniform callus growth and fracture healing.

In silico biomechanical analysis of poller screw-assisted small-diameter intramedullary nail in the treatment of distal tibial fractures

Objective: To evaluate the biomechanical effects of Poller screws (PS) combined with small-diameter intramedullary nails in the treatment of distal tibial fractures at different locations and on different planes. Methods: Nine finite element (FE) models were used to simulate the placement of the intramedullary nail (IMN) and the PS for distal tibial fractures. Structural stiffness and interfragmentary motion (IFM) through the fracture were investigated to assess the biomechanical effects of the PS. The allowable stress method was used to evaluate the safety of the construct. Results: With the axial load of 500 N, the mean axial stiffness of IMN group was 973.38 ± 95.65 N/mm, which was smaller than that at positions A and B of the coronal group and sagittal group (p < 0.05). The shear IFM of the IMN group was 2.10 ± 0.02 mm, which were smaller than that at positions A and B of the coronal group and sagittal group (p < 0.05). Under physiological load, the stresses of all internal fixation devices and the nail-bone interface were within a safe range. Conclusion: In the treatment of distal tibial fractures, placing the PS in the proximal fracture block can obtain better biomechanical performance. The IMN fixation system can obtain higher structural stiffness and reduce the IFM of the fracture end by adding PS.

Double Plating Fixation vs Distal Femoral Replacement in the Management of Distal Femoral Fractures in Geriatric Patients

Background

Distal femur fractures are considered challenging to manage, particularly in geriatric patients. Double plating (DP) is a technique that helps with earlier rehabilitation and return to preinjury level of activity. Distal femoral replacement (DFR) is an alternative technique in the management of these fractures that may help to solve problems like associated knee osteoarthritis, osteoporosis, and severely comminuted condyles. The current study compares the functional and radiological outcomes of DFR and DP in the management of these fractures among geriatric patients.

Methods

This randomized, comparative, interventional study was performed at a university hospital. A total of 30 patients who underwent DFR or DP after distal femur fractures (AO/OTA 33 A3, 33 C) were analyzed. The primary outcome was Knee Society Score (KSS), whereas secondary outcomes included postoperative complications rate, knee range of motion, reoperation rate, and operative time.

Results

No significant difference was observed between DFR and DP except for the knee component of the KSS at a 12-month interval (P = .03) and knee range of motion at a 12-month interval (P = .001), both of which were in favor of DP. No significant difference in postoperative complications (P = .06), reoperation rate (P = 1.00), or operative time (P = .06) was noted.

Conclusions

DFR and DP had comparable functional (KSS) and radiological outcomes with no significant difference in postoperative complications, reoperation rate, or operative time.

Technical Trick: Supplemental Medial Column Screw Fixation of Distal Femur Fractures Treated With a Laterally Based Locked Plate

SUMMARY

Given known failure rates after lateral plating of distal femur fractures, there is an increasing interest in augmenting fixation to improve outcomes. The addition of medial plates or intramedullary nails have been described with promising results, decreasing nonunion and varus collapse rates. However, the use of dual implants increases implant costs, adds surgical complexity, and requires a second surgical approach that may increase morbidity. A supplemental, percutaneously placed, medial column screw may provide a less invasive means of improving stability and achieving fracture union compared with lateral plating alone.

Management of Comminuted Fracture of Mandible Using Titanium Mesh

Comminuted mandibular fractures are common following a high-velocity injury to the face and jaws. The inherent nature of injury and damage to the underlying hard and soft tissues often complicate the management of comminuted fractures. Traditionally, comminuted fractures were managed by closed reduction and external skeletal fixation. Titanium mesh serves as an excellent alternative in the management of comminuted mandibular fractures. The present case report presents the successful management of comminuted mandibular fractures using titanium mesh.

Locked Lateral Plating Versus Retrograde Nailing for Distal Femur Fractures: A Multicenter Randomized Trial

OBJECTIVES

The 2 main forms of treatment for distal femur fractures are locked lateral plating and retrograde nailing. The goal of this trial was to determine whether there are significant differences in outcomes between these forms of treatment.

DESIGN

Multicenter randomized controlled trial.

SETTING

Twenty academic trauma centers.

PATIENTS/PARTICIPANTS

One hundred sixty patients with distal femur fractures were enrolled. One hundred twenty-six patients were followed 12 months. Patients were randomized to plating in 62 cases and intramedullary nailing in 64 cases.

INTERVENTION

Lateral locked plating or retrograde intramedullary nailing.

MAIN OUTCOME MEASUREMENTS

Functional scoring including Short Musculoskeletal Functional Assessment, bother index, EQ Health, and EQ Index. Secondary measures included alignment, operative time, range of motion, union rate, walking ability, ability to manage stairs, and number and type of adverse events.

RESULTS

Functional testing showed no difference between the groups. Both groups were still significantly affected by their fracture 12 months after injury. There was more coronal plane valgus in the plating group, which approached statistical significance. Range of motion, walking ability, and ability to manage stairs were similar between the groups. Rate and type of adverse events were not statistically different between the groups.

CONCLUSIONS

Both lateral locked plating and retrograde intramedullary nailing are reasonable surgical options for these fractures. Patients continue to improve over the course of the year after injury but remain impaired 1 year postoperatively.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Influence of plate size and screw distribution on the biomechanical behaviour of osteosynthesis by means of lateral plates in femoral fractures

Distal femoral fractures are fractures associated with high rates of morbidity and mortality, affecting to three different groups of individuals: younger people suffering high-energy trauma, elderly people with fragile bones and people with periprosthetic fractures around previous total knee arthroplasty. They have been classically treated with conventional plates and intramedullary nails and more recently with locked plates that have increased their indications to more types of fractures. The main objective of the present work is the biomechanical study, by means of finite element simulation, of the stability achieved in the osteosynthesis of femoral fractures in zones 4 and 5 of Wiss, by using locked plates with different plate lengths and different screw configurations, and analysing the effect of screw proximity to the fracture site. A three dimensional (3D) finite element model of the femur from 55-year-old male donor was developed, and then a stability analysis was performed for the fixation provided by Osteosynthesis System LOQTEC® Lateral Distal Femur Plate in two different fracture zones corresponding to the zones 4 and 5 according to the Wiss fracture classification. The study was focused on the immediately post-operative stage, without any biological healing process. The obtained results show that more stable osteosyntheses were obtained by using shorter plates. In the cases of longer plates, it results more convenient disposing screws in a way that the upper ones are closer to fracture site. The obtained results can support surgeons to understand the biomechanics of fracture stability, and then to guide them towards the more appropriate osteosynthesis depending on the fracture type and location.

Biomechanical study of the stiffness of the femoral locking compression plate of an external fixator for lower tibial fractures

BACKGROUND

A locking compression plate (LCP) of the distal femur is used as an external fixator for lower tibial fractures. However, in clinical practice, the technique lacks a standardized approach and a strong biomechanical basis for its stability.

METHODS

In this paper, internal tibial LCP fixator (Group IT-44), external tibial LCP fixator (Group ET-44), external distal femoral LCP fixator (Group EF-44, group EF-33, group EF-22), and conventional external fixator (Group CEF-22) frames were used to fix unstable fracture models of the lower tibial segment, and anatomical studies were performed to standardize the operation as well as to assess the biomechanical stability and adjustability of the distal femoral LCP external fixator by biomechanical experiments.

RESULTS

It was found that the torsional and flexural stiffnesses of group EF-44 and group EF-33 were higher than those of group IT-44 and group ET-44 (p < 0.05); the flexural stiffness of group EF-22 was similar to that of group IT-44 (p > 0.05); and the compressive stiffness of all three EF groups was higher than that of group ET-44 (p < 0.05). In addition, the flexural and compressive stiffnesses of the three EF groups decreased with the decrease in the number of screws (p < 0.05), while the torsional stiffness of the three groups did not differ significantly between the two adjacent groups (p > 0.05). Group CEF-22 showed the highest stiffnesses, while group ET-44 had the lowest stiffnesses (P < 0.05).

CONCLUSIONS

The study shows that the distal femoral LCP has good biomechanical stability and adjustability and is superior to the tibial LCP as an external fixator for distal tibial fractures, as long as the technique is used in a standardized manner according to the anatomical studies in this article.

[Related factors of revision of distal femoral fractures treated with lateral locking plate]

OBJECTIVE

To analyze the factors related to the need for revision surgery due to nonunion or internal fixation failure after the treatment of distal femoral fracture with lateral locking plate (LLP).

METHODS

Retrospective analysis was made of the clinical data of 130 cases with distal femoral fracture treated in our hospital from March 2005 to March 2019. SPSS 17.0 software (univariate analysis and Logistic regression analysis) was used to analyze the general condition [gender, age, body mass index (BMI), comorbidities, smoking history], injury related factors (energy of injury, open or closed injury, AO/OTA classification of fracture, fracture area distribution), operation related factors (operation time, reduction quality, postoperative infection) and construct characteristics of internal fixation.

RESULTS

Twelve of 130 patients who were included in the study underwent revisional surgery, with a revision rate 9.2%. Univariate analysis showed that there were significant differences in age, BMI, AO/OTA classification, fracture area distribution, operation time, reduction quality, length of plate/fracture area, length of plate/fracture area above condylar between the two groups (P < 0.05). Logistic regression analysis showed that AO/OTA classification (A3), supracondylar involved fracture, operation time, reduction quality and the length of the plate/fracture area above the condylar were the possible related factors (P < 0.05). Destruction of the medial support ability of the femur in comminuted type A3 fracture, supra-condylar cortex area fracture involvement, increase of the bending stress of the LLP due to poor fracture reduction quality, damage of the blood supply of fracture end due to long-time operation, and stress concentration caused by insufficient length of plate might be risk factors of revisional operation after the treatment of distal femoral fracture with LLP. For the patients who needed revision after LLP treatment, additional use of medial minimally invasive plate fixation and autologous bone transplantation, change to intramedullary nail fixation were commonly used clinical treatment strategies.

CONCLUSION

AO/OTA classification (A3), supracondylar involved fracture, long operation time, poor reduction quality and the length of the plate/fracture area above the condylar were the possible predictive factors of the revision in distal femoral fractures treated with lateral locking plate. The appropriate application of the locking plate and operation strategy are the key to reduce the revision rate in distal femoral fractures.

DISTAL FEMORAL FRACTURES FROM HIGH-ENERGY TRAUMA: A RETROSPECTIVE REVIEW OF COMPLICATION RATE AND RISK FACTORS

Objective

Determine complications' incidence and risk factors in high-energy distal femur fractures fixed with a lateral locked plate.

Methods

Forty-seven patients were included; 87.2% were male, and the average age was 38.9. The main radiographic parameters collected were distal lateral femoral angle (DFA), distal posterior femoral angle (DPLF), comminution length, plate length, screw working length, bone loss, and medial contact after reduction and plate-bone contact, location of callus formation, and implant failure. The complications recorded were nonunion, implant failure, and infection.

Results

Complex C2 and C3 fractures accounted for 85.1% of cases. Open fractures accounted for 63.8% of cases. The mean AFDL and AFDP were 79.8 4.0 and 79.3 6.0, respectively. The average total proximal and distal working lengths were 133.3 42.7, 60.4 33.4, and 29.5 21.8 mm, respectively. The infection rate was 29.8%, and the only risk factor was open fracture (p = 0.005). The nonunion rate was 19.1%, with longer working length (p = 0.035) and higher PDFA (p = 0.001) as risk factors. The site of callus formation also influenced pseudoarthrosis (p = 0.034).

Conclusion

High-energy distal femoral fractures have a higher incidence of pseudoarthrosis and infection. Nonunion has greater working length, greater AFDL, and absence of callus formation on the medial and posterior sides as risk factors. The risk factor for infection was an open fracture. Level of Evidence III; Retrospective Cohort Study .

Micromotion-based balanced drilling technology to increase near cortical strain

Objective

A micromotion-based balanced drilling system was designed based on a locking plate (LP) and far cortical locking (FCL) concept to maintain the balance of micromotions of the cortex on both sides of a fracture region. The system was tested by axial compression test.

Methods

The fracture gap was set to 2 cm, and locking screws with a diameter of 5 mm and a locking plate were used to fix it. The diameters of the two sections of the stepping drill were 3.5 mm and 5.0 mm, respectively. One of the matching drilling sleeves was a standard sleeve (eccentricity, 0 mm) and the other was an eccentric sleeve (proximal eccentricity, 1 mm). A model of the fixed locking plate (AO/ASIF 33-A3) for distal femoral fractures with a gap of 2 cm was established based on data from 42 artificial femurs (SAWBONE). According to the shape of the screw holes on the cortex, the fixed fracture models were divided into a control group (standard screw hole group X126, six cases) and an experimental group (elliptical screw hole group N, 36 cases). The experimental group was further divided into six subgroups with six cases in each (N126, N136, N1256, N1356, N12356, N123456), based on the number and distribution of the screws on the proximal fracture segment. The control, N126, and N136 groups were subjected to an axial load of 500 N, and the other groups were subjected to an axial load of 1000 N. The displacements of the kinetic head, far cortex, and near cortex were measured. The integral structural stiffness of the model and the near cortical strain were calculated. The data of each group were analyzed by using a paired t-test.

Results

When the far cortical strains were 2%, 5%, and 10%, the near cortical strains in group N126 were 0.96%, 2.35%, and 4.62%, respectively, significantly higher than those in the control group (X126) (p < 0.05). For a different distribution of the screws, when the far cortical strains were 2%, 5%, and 10%, the near cortical strains in group N126 were significantly higher than those in group N136 (p < 0.05). However, there was no significant difference between the near cortical strains in the two groups with four screws (p > 0.05). For different numbers of screws, the near cortical strains in the three-screw groups were significantly higher than those in the four-screw groups (p < 0.05), and there was no significant difference in near cortical strains among the four-, five-, and six-screw groups (p > 0.05).

Conclusion

The proposed drill and matching sleeves enabled a conventional locking compression plate to be transformed into an internal fixation system to improve the balanced motion of the near and far cortices. Thus, strain on a fracture site could be controlled by adjusting the diameter of the drill and the eccentricity of the sleeve.

Optimal design and biomechanical analysis of sandwich composite metal locking screws for far cortical locking constructs

In the interests of more flexible and less stiff bridge constructs to stimulate bone healing, the technique of far cortical locking has been designed to improve locked plating constructs in terms of stress concentration, stress shielding, and inhibition of issues around fracture healing. However, far cortical locking screws currently lack objective designs and anti-fatigue designs. This study investigates an optimization algorithm to form a special locking screw composed of various metals, which can theoretically achieve the maintenance of the excellent mechanical properties of far cortical locking constructs in terms of fracture internal fixation, while maintaining the biomechanical safety and fatigue resistance of the structure. The numerical results of our study indicate that the maximum von Mises stress of the optimized construct is less than the allowable stress of the material under each working condition while still achieving sufficient parallel interfragmentary motion. Numerical analysis of high cycle fatigue indicates that the optimized construct increases the safety factor to five. A high cycle fatigue test and defect analysis indicates that the sandwich locking constructs have better fatigue resistance. We conclude that the sandwich locking construct theoretically maintains its biomechanical safety and fatigue resistance while also maintaining excellent mechanical properties for fracture internal fixation.

Scattering and clustering the proximal screw construct in unilateral locking plate osteosynthesis of distal femoral fractures

INTRODUCTION

The importance of fixation construct in locking compression plate (LCP) is not well enlightened until recently. The aim of this study was to investigate radiological and clinical outcomes of scattering and clustering of the proximal screw fixation construct in unilateral LCP treatment of the distal femoral fractures.

MATERIALS AND METHODS

Patients who were treated for distal femoral fractures using unilateral LCP between January 2014 and December 2019 in our institute were included in this retrospective study. They were divided into groups 1 (35 cases, scattered proximal screw fixation) and 2 (35 cases, clustered proximal screw fixation). Mean follow-up period was 23.6 months for group 1 and 21.3 months for group 2. Medical history, patient demographics, injury characteristics, and surgical characteristics were reviewed and analyzed. Radiological findings including time to callus formation, bridging callus formation, union, and symmetry of the union were assessed and compared between the groups. Clinical outcomes included total blood loss during the operation, postoperative range of motion, and number of revision surgery.

RESULTS

The time for callus formation (5.8 weeks in group 1 vs. 4.1 weeks in group 2, p = 0.009) and bridging callus formation (12.5 weeks in group 1 vs. 10.7 weeks in group 2, p = 0.009) was significantly earlier in group 2. Despite similar union rates between groups, the mean time for radiological union was longer in group 2 (10.7 vs 7.4 months, p = 0.001). Though statistically insignificant, more asymmetric union was observed in group 2 (17 vs 11 cases).

CONCLUSIONS

Despite a delay in initial callus and bridging callus formation, scattering the proximal screws was better in achieving earlier and more balanced radiographic union than the clustered fixation. We recommend to avoid bridging more than five holes in the whole plate fixation construct to lessen the asymmetric callus formation and to prevent eventual plate breakage.

The geriatric distal femur fracture: nail, plate or both?

Surgical fixation of distal femur fractures in geriatric patients is an evolving topic. Unlike hip fractures, treatment strategies for distal femur fractures are ill-defined and lack substantive high-quality evidence. With an increasing incidence and an association with significant morbidity and mortality, it is essential to understand existing treatment options and their supporting evidence. Current fixation methods include the use of either retrograde intramedullary nails, or plate and screw constructs. Due to the variability in fracture patterns, the unique anatomy of the distal femur, and the presence or absence or pre-existing implants, decision-making as to which method to use can be challenging. Recent literature has sought to describe the advantages and disadvantages of each, however, there is currently no consensus on a standard of care, and little randomized evidence is available that directly compares intramedullary nails with plating. Future randomized studies comparing intramedullary nails with plating constructs are necessary in order to develop a standard of care based on injury characteristics.

A preclinical model of post-surgery secondary bone healing for subtrochanteric femoral fracture based on fuzzy interpretations

Mechanobiology plays an essential role in secondary bone fracture healing. While the introduction of newer type of plates, e.g. locking plate (LP), is becoming increasingly popular for complex femoral fractures, the conventional technique involving dynamic compression plate (DCP) remains the standard choice. The difference between the two techniques lies primarily in their screw fixation mechanisms. The present study applied 3D dynamic fracture healing scheme modelled on a subtrochanteric femur fracture, regulated by both finite element (FE) analysis and Fuzzy logic control in order to understand the spatio-temporal healing phenomena for both LP and DCP. The study further examined the influence of the two screw fixation mechanisms in determining the comparative progression of fracture healing. The problem was solved iteratively in several healing steps running in loop and accordingly, the local tissue concentrations and material properties were updated. The predicted results accorded well with various previous experimental observations. The study found an initial delay in healing associated with DCP. However, as the healing progressed, there was no significant difference in overall callus modulus. The presented preclinical model may further help predict bone healing for different implantation techniques, and thus can serve as a non-invasive tool for evaluating relative merits of extramedullary plating techniques.

Practical approach to the native distal femur fractures in the elderly: A rapid review over the recent trends

Significant work has been done in recent years on treatment strategies for distal femur fractures. Inclusive reviews on periprosthetic fractures of distal femur have been carried out recently, but there is a lack of such reviews on the subject of native distal femur fractures in the recent literature. In this narrative review, we are set out to address the latest updates on geriatric non-periprosthetic distal femur fractures, and perform a rapid review over different treatment options, arriving at a summarized proposed treatment algorithm.

[Distal femoral fractures]

CLINICAL ISSUE

Fractures of the distal femur represent rare but serious injuries with a high 1‑year mortality. An increasingly older patient population requires adapted treatment concepts.

STANDARD TREATMENT PROCEDURE

Surgical treatment using angular stable plating and retrograde nailing is the standard procedure. Conservative treatment is only indicated in cases of low demands and high perioperative risks of the patient.

TREATMENT INNOVATIONS

Primary double plate osteosynthesis and primary implantation of a distal femoral replacement represent new treatment procedures and show promising initial results in the collective of geriatric patients.

DIAGNOSTIC WORK-UP

Conventional radiographs in 2 planes and computed tomography with multiplanar and 3D reconstructions should be performed to enable an adequate assessment of the indications and treatment planning.

PERFORMANCE

Nonunion rates of plate and nail osteosyntheses range from 4% to 10%. No significant differences in long-term results can be observed. The results regarding double plate osteosynthesis and distal femoral replacement so far do not show any disadvantages compared to the existing procedures but there is still insufficient data for general recommendations.

ASSESSMENT

Complex fractures with extensive reconstructive procedures and treatment by distal femoral replacement should be performed in specialized centers.

PRACTICAL RECOMMENDATIONS

The gold standard is still surgical treatment by means of minimally invasive angular stable plate or retrograde nail osteosynthesis. Complex fracture forms require individual treatment planning considering all currently available treatment options.

Primary fibular grafting combined with double plating in distal femur fractures in elderly patients

PURPOSE

To report functional and radiological outcomes of using primary fibular graft together with double plating in distal femoral fractures in the elderly.

METHODS

A retrospective study on 30 elderly patients with comminuted distal femoral fractures managed by primary fibular grafting and double plating through an anterior midline approach has been conducted. Only isolated distal femoral fractures type 33-A3, 33-C2, and 33-C3 were included. The patient's mean age was 75.3 years. Evaluation included operative time, blood loss, time to union, knee range of motion, Sanders scoring, and presence of complications.

RESULTS

The average follow-up period was 26.6 months. Mean intraoperative blood loss was 401 ml, and mean operative time was 216 min. All patients had a knee range of motion (90-120°) during follow-up. Time for union ranged from 16 to 23 weeks with a mean of 18.4 weeks, with no cases of non-union. A total of 22 patients (73.3%) showed excellent functional outcomes, and the remaining eight (26.7%) showed good functional outcomes according to the Sanders scoring system. Only two cases (6.6%) had superficial wound infections managed conservatively. No post-operative deformity, loss of reduction, or implant failure was observed until the end of follow-up period.

CONCLUSION

Primary fibular grafting combined with double plating of comminuted distal femur fractures in patients above 70 years is an effective technique with higher rates of union and lower re-operation rates compared to other fixation modalities.

Current concepts in fracture healing: temporal dynamization and applications for additive manufacturing

Objectives

Current surgical fracture treatment paradigms, which use rigid metallic constructs to heal bones, provide reasonable clinical outcomes; however, they do not leverage recent advances in our understanding of bone healing and mechanotransduction throughout bone healing. The objective of this review was to investigate the efficacy and potential clinical applicability of surgical techniques and implants that deliberately introduce interfragmentary motion throughout the healing process.

Methods

The authors searched PubMed and Google Scholar databases for articles reporting on fracture repair using dynamic locking plates, dynamized surgical techniques, and reverse dynamization. Data collection also included assessment of additively manufactured (AM) implants that provide dynamic mechanical behaviors.

Results

Forty articles were included for final review. It was found that accelerated rates of fracture healing can be achieved with staged 2-part surgeries or dynamic implant designs. Temporal dynamization, where static fixation of bones is followed by the introduction of micromotion and controlled loading, has been shown to improve callus volume and accelerate the healing response. Reverse dynamization, where micromotion is encouraged during early callus formation and arrested later, may represent a significant advance for the treatment of critical defect injuries. Advances in AM techniques will likely provide the ability to create high-resolution implants capable of dynamized and reverse dynamized modalities.

Conclusions

There is no one-size-fits-all approach to optimization of fracture healing. However, it has been clearly demonstrated that fracture treatment can be enhanced by systematically altering the construct stiffness throughout the different phases of healing, which may be achieved with AM implant designs.

Nail diameter significantly impacts stability in combined plate-nail constructs used for fixation of supracondylar distal femur fractures

Objectives:

Plate-nail (PN) combinations have been described for fixation of supracondylar distal femur fractures. Small diameter retrograde intramedullary nails (rIMN) are commonly used. The purpose of this study was to investigate the effect of nail diameter on construct stability. We hypothesized that a larger diameter rIMN would not significantly change the stiffness of the PN construct when tested in torsional or axial loading.

Methods:

Twelve synthetic osteoporotic femurs were used to compare nail diameters in an extraarticular supracondylar distal femur fracture model (Orthopaedic Trauma Association/Arbeitsgemeinschaft für Osteosynthesefragen type 33-A3). Constructs were fixed with a 12-hole 4.5 mm pre-contoured lateral distal femoral locking plate combined with either a 9 mm (n = 6) or an 11 mm (n = 6) retrograde intramedullary nail (rIMN). Specimens were cyclically loaded in torsion and axial compression. The primary outcome was construct stiffness, calculated using the average slope of the force-displacement curves.

Results:

The 11 mm PN construct was approximately 1.6 times stiffer than the 9 mm PN construct averaged across all torsional loads (2.39 +/− 0.41 Nm/deg vs 1.44 +/− 0.17 Nm/deg) and approximately 1.3 times stiffer than the 9 mm PN construct averaged across all axial loads (506.84 +/− 44.50 N/mm vs 376.77 +/− 37.65 N/mm). There were no construct failures.

Conclusions:

In this biomechanical model, nail diameter had a significant effect on both torsional and axial stiffness in PN constructs. While the use of smaller diameter rIMNs has been proposed to allow for easier placement of implants, the effect on overall construct stiffness should be considered in the context of the patient, their fracture and desired postoperative weight bearing recommendations.

Level of Evidence: N/A

Influence of therapeutic grip exercises induced loading rates in distal radius fracture healing with volar locking plate fixation

BACKGROUND AND OBJECTIVE

Therapeutic exercises could potentially enhance the healing of distal radius fractures (DRFs) treated with volar locking plate (VLP). However, the healing outcomes are highly dependant on the patient-specific fracture geometries (e.g., gap size) and the loading conditions at the fracture site (e.g., loading frequency) resulted from different types of therapeutic exercises. The purpose of this study is to investigate the effects of different loading frequencies induced by therapeutic exercises on the biomechanical microenvironment of the fracture site and the transport of cells and growth factors within the fracture callus, ultimately the healing outcomes. This is achieved through numerical modelling and mechanical testing.

METHODS

Five radius sawbones specimens (Pacific Research Laboratories, Vashon, USA) fixed with VLP (VRP2.0+, Austofix) were mechanically tested using dynamic test instrument (INSTRON E3000, Norwood, MA). The loading protocol used in mechanical testing involved a series of cyclic axial compression tests representing hand and finger therapeutic exercises. The relationship between the dynamic loading rate (i.e., loading frequency) and dynamic stiffness of the construct was established and used as inputs to a developed numerical model for studying the dynamic loading induced cells and growth factors in fracture site and biomechanical stimuli required for healing.

RESULTS

There is a strong positive linear relationship between the loading rate and axial stiffness of the construct fixed with VLP. The loading rates induced by the moderate frequencies (i.e., 1-2 Hz) could promote endochondral ossification, whereas relatively high loading frequencies (i.e., over 3 Hz) may hinder the healing outcomes or lead to non-union. In addition, a dynamic loading frequency of 2 Hz in combination of a fracture gap size of 3 mm could produce a better healing outcome by enhancing the transport of cells and growth factors at the fracture site in comparison to free diffusion (i.e. without loading), and thereby produces a biomechanical microenvironment which is favourable for healing.

CONCLUSION

The experimentally validated numerical model presented in this study could potentially contribute to the design of effective patient-specific therapeutic exercises for better healing outcomes. Importantly, the model results demonstrate that therapeutic grip exercises induced dynamic loading could produce a better biomechanical microenvironment for healing without compromising the mechanical stability of the overall volar locking plate fixation construct.

Boundary Conditions Matter - Impact of Test Setup On Inferred Construct Mechanics in Plated Distal Femur Osteotomies

The mechanics of distal femur fracture fixation has been widely studied in bench tests that employ a variety of approaches for holding and constraining femurs to apply loads. No standard test methods have been adopted for these tests and the impact of test setup on inferred construct mechanics has not been reported. Accordingly, the purpose of this study was to use finite element models to compare the mechanical performance of a supracondylar osteotomy with lateral plating under conditions that replicate several common bench test methods. A literature review was used to define a parameterized virtual model of a plated distal femur osteotomy in axial compression loading with four boundary condition sets ranging from minimally to highly constrained. Axial stiffness, longitudinal motion, and shear motion at the fracture line were recorded for a range of applied loads and bridge spans. The results showed that construct mechanical performance was highly sensitive to boundary conditions imposed by the mechanical test fixtures. Increasing the degrees of constraint, for example by potting and rigidly clamping one or more ends of the specimen, caused up to a 25x increase in axial stiffness of the construct. Shear motion and longitudinal motion at the fracture line, which is an important driver of interfragmentary strain, was also largely influenced by the constraint test setup. These results suggest that caution should be used when comparing reported results between bench tests that use different fixtures and that standardization of testing methods is needed in this field.

Comparison between external locking plate fixation and conventional external fixation for extraarticular proximal tibial fractures: a finite element analysis

Background

Good clinical outcomes for locking plates as an external fixator to treat tibial fractures have been reported. However, external locking plate fixation is still generally rarely performed. This study aimed to compare the stability of an external locking plate fixator with that of a conventional external fixator for extraarticular proximal tibial fractures using finite element analysis.

Methods

Three models were constructed: (1) external locking plate fixation of proximal tibial fracture with lateral proximal tibial locking plate and 5-mm screws (ELP), (2) conventional external fixation of proximal tibial fracture with an 11-mm rod and 5-mm Schanz screws (EF-11), and (3) conventional external fixation of a proximal tibial fracture with a 7-mm rod and 5-mm Schanz screws (EF-7). The stress distribution, displacement at the fracture gap, and stiffness of the three finite element models at 30-, 40-, 50-, and 60-mm plate–rod offsets from the lateral surface of the lateral condyle of the tibia were determined.

Results

The conventional external fixator showed higher stiffness than the external locking plate fixator. In all models, the stiffness decreased as the distance of the plate–rod from the bone surface increased. The maximum stiffness was 121.06 N/mm in the EF-11 model with 30-mm tibia–rod offset. In the EF-7 model group, the maximum stiffness was 40.00 N/mm in the model with 30-mm tibia–rod offset. In the ELP model group, the maximum stiffness was 35.79 N/mm in the model with 30-mm tibia–plate offset.

Conclusions

Finite element analysis indicated that external locking plate fixation is more flexible than conventional external fixation and can influence secondary bone healing. External locking plate fixation requires the placement of the plate as close as possible to the skin, which allows for a low-profile design because the increased distance from the plate to the bone can be too flexible for bone healing. Further experimental mechanical model tests are necessary to validate these finite element models, and further biological analysis is necessary to evaluate the effect of external locking plate fixation on fracture healing.

A systematic review of the use of titanium versus stainless steel implants for fracture fixation

Background:

Controversy exists regarding the use of titanium and stainless steel implants in fracture surgery. To our knowledge, no recent, comprehensive review on this topic has been reported.

Purpose:

To perform a systematic review of the evidence in the current literature comparing differences between titanium and stainless steel implants for fracture fixation.

Methods:

A systematic review of original research articles was performed through the PubMed database using PRISMA guidelines. Inclusion criteria were English-language studies comparing titanium and stainless steel implants in orthopaedic surgery, and outcome data were extracted.

Results:

The search returned 938 studies, with 37 studies meeting our criteria. There were 12 clinical research articles performed using human subjects, 11 animal studies, and 14 biomechanical studies. Clinical studies of the distal femur showed the stainless steel cohorts had significantly decreased callus formation and an increased odds radio (OR 6.3, 2.7-15.1; P < .001) of nonunion when compared with the titanium plate cohorts. In the distal radius, 3 clinical trials showed no implant failures in either group, and no difference in incidence of plate removal, or functional outcome. Three clinical studies showed a slightly increased odds ratio of locking screw breakage with stainless steel intramedullary nails compared with titanium intramedullary nails (OR 1.52, CI 1.1-2.13).

Conclusion:

Stainless steel implants have equal or superior biomechanical properties when compared with titanium implants. However, there is clinical evidence that titanium plates have a lower rate of failure and fewer complications than similar stainless steel implants in some situations. Although our review supports the use of titanium implants in these clinical scenarios, we emphasize that further prospective, comparative clinical studies are required before the conclusions can be made.

[Research on the nature of micromovement and the biomechanical staging of fracture healing]

Objective

To explore the nature of micromovement and the biomechanical staging of fracture healing.

Methods

Through literature review and theoretical analysis, the difference in micromovement research was taken as the breakthrough point to try to provide a new understanding of the role of micromovement and the mechanical working mode in the process of fracture healing.

Results

The process of fracture healing is the process of callus generation and connection. The micromovement is the key to start the growth of callus, and the total amount of callus should be matched with the size of the fracture space. The strain at the fracture end is the key to determine the callus connection. The strain that can be tolerated by different tissues in the fracture healing process will limit the micromovement. According to this, the fracture healing process can be divided into the initiation period, perfusion period, contradiction period, connection period, and physiological period, i.e., the biomechanical staging of fracture healing.

Conclusion

Biomechanical staging of fracture healing incorporates important mechanical parameters affecting fracture healing and introduces the concepts of time and space, which helps to understand the role of biomechanics, and its significance needs further clinical test and exploration.

A Retrospective Study of Postoperative Development of Implant-Induced Osteoporosis in Radial-Ulnar Fractures in Toy Breed Dogs Treated with Plate Fixation

OBJECTIVE

 This study aimed to evaluate implant-induced osteoporosis (IIO) development in toy breed dogs treated using internal fixation with digital radiographs as the index of pixel values.

STUDY DESIGN

 There were 226 cases (236 limbs) of toy breed dogs with radial-ulnar fractures. Pixel values were measured on radiographs immediately, 2 weeks and 1 to 12 months after surgery. The ratio of pixel values (PVR) represented the bone mineral areal density based on the humeral condyle in the same image. The dogs were grouped based on the fixation methods, age and status of destabilization.

RESULTS

 There was a significant decrease in the PVR at 1 to 12 months postoperatively for all cases. There were not any significant differences in PVR of antebrachial fractures between those repaired with plates using locking head screws, cortex screws or a combination of locking and cortex screws. Implant-induced osteoporosis persisted at 1 to 12 months postoperatively in dogs aged ≧6 months, while the PVR increased after 3 months in dogs aged <6 months. Based on the destabilization method, there was a significant increase in the PVR at 3 months in the plate removal group.

CONCLUSION

 This study suggests that IIO occurs in small dogs treated with plates and screws. Moreover, patients aged < 6 months showed an early postoperative recovery of bone mineral areal density. Further, screw and plate removal could contribute to the recovery of bone mineral areal density.

Biomechanical behavior of retrograde intramedullary nails in distal femoral fractures

Fractures of the distal femur affect three different groups of individuals: younger people suffering high-energy trauma, elderly people with fragile bones and people with periprosthetic fractures around previous total knee arthroplasty. Main indications of intramedullary nailing are for supracondylar fractures type A or type C of the AO classification. The main objective of the present work is to analyze, by means of FE simulation, the influence of retrograde nail length, considering different blocking configurations and fracture gaps, on the biomechanical behavior of supracondylar fractures of A type. A three dimensional (3D) finite element model of the femur from 55-year-old male donor was developed, and then a stability analysis was performed for the fixation provided by the retrograde nail at a distal fracture with different fracture gaps: 0.5 mm, 3 mm y 20 mm, respectively. Besides, for each gap, three nail lengths were studied with a general extent (320 mm, 280 mm and 240 mm), considering two transversal screws (M/L) at the distal part and different screw combinations above the fracture. The study was focused on the immediately post-operative stage, without any biological healing process. In view of the obtained results, it has been demonstrated new possibilities of blocking configuration in addition to the usual ones, which allows establishing recommendations for nail design and clinical practice, avoiding excessive stress concentrations both in screws, with the problem of rupture and loss of blocking, and in the contact of nail tip with cortical bone, with the problem of a new stress fracture.

The effect of surgeon-controlled variables on construct stiffness in lateral locked plating of distal femoral fractures

Background

Nonunion following treatment of supracondylar femur fractures with lateral locked plates (LLP) has been reported to be as high as 21 %. Implant related and surgeon-controlled variables have been postulated to contribute to nonunion by modulating fracture-fixation construct stiffness. The purpose of this study is to evaluate the effect of surgeon-controlled factors on stiffness when treating supracondylar femur fractures with LLPs:

Does plate length affect construct stiffness given the same plate material, fracture working length and type of screws?

Does screw type (bicortical locking versus bicortical nonlocking or unicortical locking) and number of screws affect construct stiffness given the same material, fracture working length, and plate length?

Does fracture working length affect construct stiffness given the same plate material, length and type of screws?

Does plate material (titanium versus stainless steel) affect construct stiffness given the same fracture working length, plate length, type and number of screws?

Methods

Mechanical study of simulated supracondylar femur fractures treated with LLPs of varying lengths, screw types, fractureworking lenghts, and plate/screw material. Overall construct stiffness was evaluated using an Instron hydraulic testing apparatus.

Results

Stiffness was 15 % higher comparing 13-hole to the 5-hole plates (995 N/mm849N vs. /mm, p = 0.003). The use of bicortical nonlocking screws decreased overall construct stiffness by 18 % compared to bicortical locking screws (808 N/mm vs. 995 N/mm, p = 0.0001). The type of screw (unicortical locking vs. bicortical locking) and the number of screws in the diaphysis (3 vs. 10) did not appear to significantly influence construct stiffness (p = 0.76, p = 0.24). Similarly, fracture working length (5.4 cm vs. 9.4 cm, p = 0.24), and implant type (titanium vs. stainless steel, p = 0.12) did also not appear to effect stiffness.

Discussion

Using shorter plates and using bicortical nonlocking screws (vs. bicortical locking screws) reduced overall construct stiffness. Using more screws, using unicortical locking screws, increasing fracture working length and varying plate material (titanium vs. stainless steel) does not appear to significantly alter construct stiffness. Surgeons can adjust plate length and screw types to affect overall fracture-fixation construct stiffness; however, the optimal stiffness to promote healing remains unknown.

Hybrid locked medial plating in dual plate fixation optimizes the healing of comminuted distal femur fractures: A retrospective cohort study

OBJECTIVES

Dual plate fixation has been reported to be effective in the treatment of comminuted distal femur fractures (DFFs). However, optimized use of the medial plate and screws is less studied. This study aimed to evaluate the effect of a hybrid configuration of the medial plate in dual plate fixation of comminuted DFFs in promoting fracture healing.

MATERIALS AND METHODS

We retrospectively analyzed 62 patients with comminuted DFFs (AO/OTA 33-A3/33-C2/33-C3) from January 2015 to March 2020, who were either fixed with lateral locked plating augmented with hybrid locked medial plating (LP-HLMP, n = 32) or lateral locked plating (LLP, n = 30) alone. Specifically, compression screws were applied in the middle of the medial plate and flanked by locking ones at both ends. Baseline characteristics, radiological and clinical outcomes were reviewed and analyzed. Multivariate logistic regression analysis was used to identify predictive factors for early fracture healing, and risk factors for delayed union/nonunion.

RESULTS

Demographics including age, gender, smoking, diabetes, and injury mechanism were comparable between the two groups. Reduction quality was better in the LP-HLMP group (p < 0.001). Although the LP-HLMP group experienced longer duration of surgery (125 min vs. 100 min, p < 0.001), sign of healing at 3 months was more obvious in this group (75%, 24/32 vs. 30%, 9/30; p < 0.001). The LP-HLMP group also presented with higher union rate (93.8%, 30/32 vs. 56.7%, 17/30; p = 0.001) and lower reoperation rate (0%, 0/32 vs. 13.3%, 4/30; p = 0.049). Kolment score showed no statistical significance between the two groups. Multivariate analysis revealed that younger age (< 60 years) (OR 5.99, 95%CI 1.16 - 31.03; p = 0.001) and LP-HLMP fixation (OR 45.90, 95% CI 4.78 - 440.56; p = 0.001) predict early healing; while smoking (OR 17.80, 95% CI 2.41 - 131.49; p = 0.01) and fracture translation (OR 3.49, 95% CI 1.46 - 8.32; p = 0.01) were identified as risk factors for delayed union/nonunion.

CONCLUSION

Hybrid locked medial plating in this study favors the healing of comminuted DFFs and reduces reoperation. Additionally, smoking and suboptimal reduction (translation) predict delayed union/nonunion.

Comparing Intramedullary Nailing Versus Locked Plating in the Treatment of Native Distal Femur Fractures: Is One Superior to the Other?

INTRODUCTION

Distal femur fractures make up < 1% of all fractures and 3-6% of all femur fractures. In the literature, both intramedullary nailing (IMN) and locked plating (LP) have shown favorable results, but there is no consensus on a gold standard. The purpose of this systematic review is to compare outcomes of native distal femur fractures treated via IMN versus LP in an effort to determine if one is superior to the other.

METHODS

Systematic review of MEDLINE, EMBASE, and Cochrane Library databases was conducted according to PRISMA guidelines. Only articles published within the last ten years were included. Evidence and study quality were evaluated with the MQOE and Oxford Criteria.

RESULTS

Forty-six articles were included in the review. Fractures treated with IMN were found to have a 93.9% union rate, an average time to union of 19.2 weeks, an average arc of motion of 105.1 degrees, with an average of 14.4 degrees of malalignment. Fractures treated with LP were found to have a 90.2% union rate, an average time to union of 20.5 weeks, an average arc of motion of 104 degrees, with an average of 12.6 degrees of malalignment.

CONCLUSION

Compiled data comparisons revealed no differences in union rate, malalignment, time to union, average arc of motion, or complication rates requiring a return to the operating room. Until higher level randomized data is available, either IMN or LP are acceptable methods of treatment for native distal femur fractures.

Axial Micromotion Locking Plate Construct Can Promote Faster and Stronger Bone Healing in an Ovine Osteotomy Model

Fixing bone fractures with controlled axial interfragmentary micromotion improves bone healing; however, the optimal type of implant construct for this purpose is still lacking. The present study describes a novel axial micromotion locking plate (AMLP) construct that allows axial interfragmentary micromotion of 0.3 or 0.6 mm. We investigated whether the AMLP constructs enhance bone healing compared to an ordinary locking plate (LP) using an ovine osteotomy model. The stiffness of the constructs was tested under axial loading. We created a 3-mm osteotomy in the left hind leg tibia of sheep that was then stabilized with a 0.3- or 0.6-mm AMLP or LP construct (n = 6/group). Bone healing was monitored weekly by X-ray radiography starting from week 3 after surgery. At week 9, the specimens were collected and evaluated by computed tomography and torsional testing. We found that the AMLPs had a lower stiffness than the LP; in particular, the stiffness of the 0.6-mm AMLP construct was 86 and 41% lower than that of the LP construct for axial loads <200 and >200 N, respectively. In the in vivo experiments, tibial osteotomies treated with the 0.6-mm AMLP construct showed the earliest maximum callus formation (week 5) and the highest volume of bone callus (9.395 ± 1.561 cm³ at week 9). Specimens from this group also withstood a 27% greater torque until failure than those from the LP group (P = 0.0386), with 53% more energy required to induce failure (P = 0.0474). These results demonstrate that AMLP constructs promote faster and stronger bone healing than an overly rigid LP construct. Moreover, better bone healing was achieved with an axial micromotion of 0.6 mm as compared to 0.3 mm.

Infected Non-Union of the Distal Femur

The reported levels of non-union in the lateral locking plate differ widely, with some early studies showing rates of less than 6% and up to 17%-21% in more recent studies. We report a case where better results were shown by a non-union treated with distal femoral nailing with allogenic grafting.

Influence of gap distance between bone and plate on structural stiffness and parallel interfragmental movement in far-cortical locking technique - a biomechanical study

Sufficient interfragmental movement is the key to successful fracture healing in the theory of secondary bone healing. The far-cortical locking technique enables both stiffness reduction and parallel motion for ideal callus formation and fracture healing, but the influence of plate-bone gap on the performance of far-cortical locking technique remains unclear. The current study conducted a series of finite element analyses with mechanical validation to clarify this issue. Plate-bone gaps were assigned by 1, 2, 3, and 4 mm in a simulated mid-shaft fracture model fixed with locking plate and six semi-rigid locking screws. Axial compressive load to 500 N was applied to the fixation structure to evaluate the structural stiffness, pattern of interfragmental movement (parallel motion), and stresses on the screws. Results revealed the increased plate-bone gaps reduced the structural in order (315.3, 288.8, 264.9, and 243.4 N/mm). Tilting angles for determining parallel interfragmental movement (1.58°-1.85°) and stresses on semi-rigid screws for evaluating implant safety were not severely altered. Greater stresses were found on the screws adjacent to the fracture site in all simulated models. The current study suggested that 1 mm gap between the locking plate and the bone shall be ideal in view of parallel motion achieved balanced callus formation in far-cortical locking technique. Issue of reducing structural stiffness with limited plate-bone gap distance should be further investigated.

Interfragmentary lag screw and locking plate combination in simple distal femoral fractures: A finite element analysis

OBJECTIVE

The aim of this study was to evaluate the strength of the locking plate and lag screw construct that is applied in two different working lengths on the simple distal femur fracture model with a finite element analysis (FEA) method.

METHODS

From the computerized tomography scan data of a 60-year-old healthy male, the AO/OTA 33A1-type fracture model was simulated; the fracture gap was stabilized with the models of locking plate construct with (groups C and D) or without an interfragmentary lag screw (groups A and B). Furthermore, 102-mm plate (groups A and C) and 82-mm plate working lengths (groups B and D) were tested using FEA. Two loading conditions (axial compression and torsion) were applied at the center of the femoral head. Construct stiffness, interfragmentary micromotion, and the peak von Mises stress (VMS) on the plate were assessed.

RESULTS

Group D provided the highest axial stiffness (1347 N/mm), and group A was the weakest (439 N/mm). With the lag screw, shear micromotion remained generally low compared with that without the screw for all axial and torsional load levels and for both plate working lengths, i.e., 0.23 mm with lag screw versus 0.43 mm without lag screw (102 mm working length, 700 N). The percentage decreases of shear micromotion under axial (350/700/1400 N) and torsional loads for the 102-mm working length were >22% and 73%, respectively; while those for the 82-mm working length were >28% and 33%, respectively. The reduction of axial micromotion was observed with the lag screw for all axial load levels as well as for both plate working lengths, i.e., 0.33 mm with lag screw versus 0.87 mm without lag screw (102-mm working length, 700 N). The percentage decreases of axial micromotion under axial loading (350/700/1400 N) for 102 mm and 82 mm working lengths were >42% and 50%, respectively. The peak VMS on the plate stayed generally low with lag screw compared with without lag screw throughout all tested load levels, as well as for both plate working lengths, i.e., 124.26 MPa versus 244.39 MPa (102 mm working length, 700 N). The percentage decreases of the peak VMS under axial (350/700/1400 N) and torsional loads for the 102-mm working length were >40% and 69%, respectively, while those for the 82-mm working length were >47% and 61%, respectively.

CONCLUSION

The current FEA concludes that in a simple distal femur fracture, adding a lag screw to a locking plate construct provides better torsional stability with a 102-mm plate working length and better axial stability with a 82-mm plate working length. Additionally, the strength of the materials is increased and implant failure can be minimized by using this technique.