Supplemental Fixation of Supracondylar Distal Femur Fractures: A Biomechanical Comparison of Dual-Plate and Plate-Nail Constructs

Design and validation of finite element models for the assessment of post-fixation distal femur fracture motion

Fracture site motion is thought to play an important role in the healing of complex fractures of the distal femur via mechanotransduction. Measuring this motion in vivo is challenging, and this has led researchers to turn to finite element modeling approaches to gain insights into the mechanical environment at the fracture site. Developing a systematic understanding of the effect of different model choices for distal femur fractures may allow more accurate prediction of fracture site motion from these types of simulations. In this study, we aim to assess the effect of four different modeling choices and parameters. We looked at the effect of using bone specific density distributions vs generic values, employing landmark-based geometry generation, varying fracture alignment within clinically relevant ranges, and determining whether direct apposition of the fracture to the plate was achieved. For validation, five cadaveric femurs had fractures created and repaired with plated constructs, and these were then loaded and fracture site motion was directly measured. We found that using landmark based bone geometry and patient-specific bone density distributions had a minimal effect on the overall model predictions. Changing the alignment, particularly into varus and procurvatum could have a large (>50%) effect on predicted shear motion, as could direct apposition of the bone to the plate. These findings demonstrate that modeling choices can play an important role in simulating distal femur fracture mechanics, and it is particularly critical that patient customized models attempt to accurately represent alignment of the bone fragments and lateral plate apposition.

Relative contribution of the nail and plate to a nail-plate construct for comminuted distal femoral fractures

The purpose of this study was to assess the biomechanical contributions of the nail and the plate individually to a complete nail-plate construct in the setting of comminuted distal femur fractures. For this biomechanical study, comminuted extra-articular distal femur fractures were created in 24 synthetic osteoporotic femur models. These were then split into three groups: the nail-only group, the plate-only group, and the nail-plate group. After fixation, each specimen underwent sequential axial and torsional loading, and axial and torsional stiffness were calculated and compared. The addition of a nail to a plate-only construct increased axial stiffness by 19.7% and torsional stiffness by 59.4%. The plate-only group and nail-plate group both demonstrated significantly greater axial and torsional stiffness than the nail-only group at all levels of axial and torsional load. (p < 0.001) At 1000 and 2000 N of cyclic loading, the nail-plate group demonstrated significantly greater axial stiffness than the plate-only group (p ≤ 0.018). The nail-plate group demonstrated greater torsional stiffness than the plate-only groups at all levels of torsional loading (p < 0.001). In osteoporotic comminuted distal femur fracture models, most of the axial stiffness in a nail-plate construct comes from the plate. While the combination of the two constructs is not fully additive, the plate contributes the majority of the axial and torsional stiffness in a nail-plate construct. The supplementation of the plate with a nail primarily helps to increase resistance to rotational forces. Level of Evidence: III.

The Effects of Unitizing Nail-Plate Constructs in Distal Femur Fractures: A Biomechanical Study

OBJECTIVES

To assess the biomechanical differences between linked and unlinked constructs in young and osteoporotic cadavers in addition to osteoporotic sawbones.

METHODS

Intraarticular distal femur fractures with comminuted metaphyseal regions were created in three young matched pair cadavers, three osteoporotic matched pair cadavers, and six osteoporotic sawbones. Precontoured distal femur locking plates were placed in addition to a standardized retrograde nail, with unitized constructs having one 4.5 mm locking screw placed distally through the nail. Nonunitized constructs had seven 4.5 mm locking screws placed through the plate around the nail, with one 5 mm distal interlock placed through the nail alone. Cadaveric specimens were subjected to axial fatigue loads between 150 and 1500 N (R Ratio = 10) with 1 Hx frequency for 10,000 cycles. Sawbones were axially loaded at 50% of the ultimate load for fatigue testing to achieve runout, with testing performed with 30 and 300 N (R Ratio = 10) loads with 1 Hz frequency for 10,000 cycles.

RESULTS

In young cadavers, there was no difference in the mean cyclic displacement of the unitized constructs (1.51 ± 0.62mm) compared to the non-unitized constructs (1.34 ± 0.47mm) (Figure 4A), (p = 0.722). In osteoporotic cadavers, there was no difference in the mean cyclic displacement of the unitized constructs (2.46 ± 0.47mm) compared to the non-unitized constructs (2.91 ± 1.49mm) (p =0.639). There was statistically no significant difference in cyclic displacement between the unitized and non-unitized groups in osteoporotic sawbones(p = 0.181).

CONCLUSIONS

Linked constructs did not demonstrate increased axial stiffness or decreased cyclical displacement in comparison to unlinked constructs in young cadaveric specimens, osteoporotic cadaveric specimens, or osteoporotic sawbones.

Quantitative-MRI analysis of the effects of retrograde nailing on vascularity of the distal femur: A cadaveric study

BACKGROUND

Distal femur fractures remain treatment challenges with a considerable postoperative non-union rate. Concern remains that surgery may compromise osseous vascularity. This study aimed to determine effects of retrograde femoral intramedullary nailing (RFIN) on distal femur vascularity, and the locations of the middle genicular artery terminal branches in relation to the standard RFIN entry point.

METHODS

Five lower limb cadaveric pairs were obtained (ten specimens). Experimental limbs were randomly assigned, and contralateral limbs served as controls. An 11 mm femoral nail was implanted in experimental specimens. Controls only underwent a medial parapatellar incision with capsulotomy. Quantitative pre- and post-contrast-MRI was performed to assess arterial contributions to distal femur regions. Osseous vascularity was further evaluated with contrast-CT imaging. Next, specimens were injected with latex medium, and dissection was performed to assess extraosseous vasculature.

RESULTS

No statistically significant differences were found with quantitative-MRI in experimental and control groups for the entire distal femur or individual regions. The experimental group demonstrated a small mean decrease of 1.4% in distal femur arterial contributions. CT and anatomic dissection confirmed maintenance of middle genicular artery terminal branches. On average, 3.3 (±1.3) terminal branches entered along the posterior intercondylar notch. A mean distance of 15.2 mm (±6.9 mm) was found between the posterior RFIN entry point and these terminal branches.

CONCLUSIONS

RFIN did not significantly alter arterial contributions to the distal femur or disrupt the middle genicular artery terminal branches. However, care must be taken to ensure nail entry point accuracy given proximity of the entry point to terminal branches.

Biomechanical testing of a computationally optimized far cortical locking plate versus traditional implants for distal femur fracture repair

BACKGROUND

This study experimentally validated a computationally optimized screw number and screw distribution far cortical locking distal femur fracture plate and compared the results to traditional implants.

METHODS

24 artificial femurs were osteotomized with a 10 mm fracture gap 60 mm proximal to the intercondylar notch. Three fixation constructs were used. (i) Standard locking plates secured with three far cortical locking screws inserted according to a previously optimized distribution in the femur shaft (n = 8). (ii) Standard locking plates secured with four standard locking screws inserted in alternating plate holes in the femur shaft (n = 8). (iii) Retrograde intramedullary nail secured proximally with one anterior-posterior screw and distally with two oblique screws (n = 8). Axial hip forces (700 and 2800 N) were applied while measuring axial interfragmentary motion, shear interfragmentary motion, and overall stiffness.

FINDINGS

Experimental far cortical locking plate results compared well to published computational findings. Far cortical locking femurs contained the highest axial motion within the potential ideal range of 0.2-1 mm and a sheer-to-axial motion ratio < 1.6 at toe-touch weight-bearing (700 N). At full weight-bearing (2800 N), Standard locking-plated femurs had the only axial motion within 0.2-1 mm but had an excess shear-to-axial motion ratio. Nail-implanted femurs underperformed at both forces.

INTERPRETATION

For toe-touch weight-bearing, the far cortical locking construct provided optimal biomechanics to allow moderate motion, which has been suggested to encourage early callus formation. Conversely, at full weight-bearing, the standard locking construct offered the biomechanical advantage on fracture motion.

A novel anatomical locked medial femoral condyle plate: a biomechanical study

BACKGROUND

Fixation with a distal lateral femoral plate is a standard approach in treating osteoporotic or comminuted supracondylar femur fractures. However, in clinical practice, this method may prove inadequate, necessitating the application of a plate on the medial side of the distal femur. The aim of this study is to perform a biomechanical evaluation of the newly manufactured anatomically locked plate applied to the distal medial femoral condyle.

MATERIALS AND METHODS

The plate underwent 2 biomechanical tests by simulating an AO/OTA 33A3 type supracondylar fracture model on synthetic femur bones. The samples were divided into three groups. Fracture fixations were carried out on the medial side using the distal femur medial anatomical locking plate (DFMALP) in group A samples, on the lateral side using the distal femur lateral anatomical locking plate in group B samples, and on both sides in group C samples.

RESULTS

In the axial compression test, stability was preserved 23% more in group C than in group B. During the cyclic axial compression test, total displacement was 21% less in group C than in group B. Group A was collapsed at early cycle degrees.

CONCLUSION

In our study, it was observed that the application of DFMALP in conjunction with the lateral plate in AO/OTA 33A3 fragmented supracondylar femur fractures significantly enhanced biomechanical fracture stability.

LEVEL OF EVIDENCE

This is a Level 2 prospective, randomized controlled study.

Distal femur fractures: basic science and international perspectives

Distal femur fractures are challenging injuries to manage, and complication rates remain high. This article summarizes the international and basic science perspectives regarding distal femoral fractures that were presented at the 2022 Orthopaedic Trauma Association Annual Meeting. We review a number of critical concepts that can be considered to optimize the treatment of these difficult fractures. These include biomechanical considerations for distal femur fixation constructs, emerging treatments to prevent post-traumatic arthritis, both systemic and local biologic treatments to optimize nonunion management, the relative advantages and disadvantages of plate versus nail versus dual-implant constructs, and finally important factors which determine outcomes. A robust understanding of these principles can significantly improve success rates and minimize complications in the treatment of these challenging injuries.

Comparison of radiological and functional results in osteoporotic distal femur fractures operated with single plating, lateral incision, and double plating, anterior paramedial incision: A retrospective study

Treatment of osteoporotic distal femur fractures is often complicated by a high rate of nonunion and varus collapse. For such fractures, lateral plating with lateral incision and double plating with anterior paramedial incision have shown promising results in the recent literature. The hypothesis of this study was that bilateral plating of comminuted distal femur fractures in osteoporotic patients would result in higher union rates and lower revision rates compared to an isolated lateral locking plate. The study included 56 patients (23 males, 33 females) with supracondylar femur fracture. According to the OA/OTA classification, 9 were type A3, 8 were A2, 13 were C1, 16 were C2, and 10 were C3. The mean follow-up period was 12 months, with 29 patients treated using lateral mini-incision, lateral locking plate, and 27 patients treated with anterior paramedial incision, dual plating. The clinical and radiological results were evaluated. The mean duration of radiological union in the studied population was 15 ± 2.1 months (range, 11-21 months) in the single plate group (Group A), and 13.5 ± 2.6 months (range, 9-19 months) in the double plate group (Group B). Mean ROM was 112.3° and flexion contracture 4° in Group A, and ROM 108.3° and flexion contracture 6.7° in Group B. (P = .15). The average Western Ontario and McMaster Universities Arthritis Index (WOMAC) score was 85.6 points in Group A and 83.5 points in Group B (P = .2278). The postoperative anteversion measurement in the operated extremity ranged from -15 to 19 in Group A, and from 5 to 18 in Group B. When the anteversion degrees were compared between the injured and uninjured extremities in the postoperative period, a significant difference was observed within Group A (P = .0018), but no significant difference was observed in Group B (P = .2492). Dual plate fixation using the anterior paramedial approach is an effective operative method for osteoporotic distal femur fractures. This has many advantages such as precise exposure, easy manipulation, anatomic reduction, and stable fixation. However, for surgical indications and medial bone defects > 1 cm, grafting should be performed.

What Is the Likelihood of Union and Frequency of Complications After Parallel Plating and Supplemental Bone Grafting for Resistant Distal Femoral Nonunions?

BACKGROUND

Management of resistant distal femur nonunions is challenging because patients not only have disability from an unhealed fracture, but also often have a shortened femur, stiff knee, deformities, and bone defects to address during revision surgery. Dual plating of the distal femur in such a setting can maintain stability that allows the nonunion to heal while also addressing bone defects and correcting deformities simultaneously. Dual-plating techniques that have been described lack standardization with regard to the size and type of medial-side implants and configuration of the dual-plate construct.

QUESTIONS/PURPOSES

(1) What proportion of patients achieve radiologic evidence of union after parallel plating of resistant distal femoral nonunions? (2) What improvements in function are achieved with this approach, as assessed by improvements in femoral length discrepancy, knee flexion, and patient-reported outcome scores? (3) What complications are associated with the technique?

METHODS

Between 2017 and 2020, the senior author of this study treated 38 patients with resistant distal femoral nonunions, defined here as nonunions that persisted for more than 12 months since the injury despite a minimum of two previous internal fixation procedures. During the study period, our preferred technique for treating aseptic, resistant distal femoral nonunions was to use dual plates in a parallel configuration augmented with autografts. Of 38 patients, three patients with active signs of infection who underwent resection and reconstruction using bone transport techniques and two patients older than 65 years with deficient distal femur bone stock who underwent endoprosthetic reconstruction were excluded. Of the 33 included patients, 67% (22 of 33) were male. The median age was 40 years (range 20 to 67 years). Nonunion was articular and metaphyseal in 13 patients and metaphyseal only in 20 patients. Our surgical approach was to remove existing implants, perform intraoperative culturing to rule out infection, debride the nonunion, correct the deformity, perform intra-articular and extra-articular lysis of adhesions with quadriceps release, and apply fixation using medial and lateral fixed-angle anatomic locked implants positioned in a parallel configuration. Every attempt to improve length was undertaken, and the defects were filled with autografts. A total of 97% of patients were followed until union occurred (one of 33 was lost to follow-up before union was documented), and 79% (26 of 33) were assessed for functional outcomes at a minimum of 2 years (median 38 months [range 25 to 60 months]) after excluding patients lost to follow-up and those in whom union did not occur after parallel plating. Union was defined as evidence of central trabecular bridging on AP radiographs and posterior cortical bridging on lateral radiographs. These radiologic criteria were defined to overcome difficulties in assessing radiologic healing in patients with lateral and medial plates. With parallel plating, bridging trabecular bone along the posterior cortex on lateral radiographs and the central region on AP radiographs is visualized and can be appreciated and interpreted as evidence of healing in two orthogonal planes. Preoperative and follow-up clinical assessment of knee ROM, the extent of femoral length correction based on calibrated femoral radiographs before and after surgery, and the evaluation of improvement in lower limb function based on the preoperative and follow-up differences in responses to the lower extremity functional scale (LEFS) were studied (the LEFS is scored from 0 to 80, with higher scores representing better function). Complications and secondary surgical procedures to address them were abstracted from a longitudinally maintained trauma database.

RESULTS

Sixty-seven percent (22 of 33) of nonunions showed radiologic healing by 24 weeks, and another 24% (eight of 33) healed by 36 weeks. Six percent (two of 33) did not unite, and one patient was lost to follow-up before union was documented. In the 79% (26 of 33) of patients available for final functional outcome assessment, the median femoral shortening had improved from 2.4 cm (range 0 to 4 cm) to 1.1 cm (range 0 to 2.3 cm; p < 0.001), and the median knee ROM had improved from 70° (range 20° to 110°) to 100° (range 50° to 130°; p = 0.002) after surgery. The median LEFS score improved to 63 (range 41 to 78) compared with 22 (range 15 to 33; p < 0.001) before surgery. Serious complications, including major thromboembolic events, iliac graft site infection, knee stiffness (flexion < 60°), and medial plate impingement necessitating removal, were seen in 30% (10 of 33) of patients. Secondary surgical interventions were performed in 24% (eight of 33) of patients to address procedure-related complications.

CONCLUSION

Based on our findings, a high likelihood of union and improvements in knee and lower limb function can be expected with parallel plating of resistant distal femur nonunions using anatomic locked plates. However, the increased frequency of complications observed in our study suggests the need for improvements in dual-plating techniques and to explore possible alternative fixation methods through larger multicenter comparative studies.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Dual Plate Fixation of Periprosthetic Distal Femur Fractures

OBJECTIVES

Dual implants for distal femur periprosthetic fractures is a growing area of interest for these challenging fractures with dual plating (DP) emerging as a viable construct for these injuries. In the current study, an experience with DP constructs is described.

METHODS

DESIGN

Retrospective case series with comparison group.

SETTING

Level 1 academic trauma center.

PATIENT SELECTION CRITERIA

Adults >50 years old sustaining comminuted OTA/AO 33-A2 or 33-A3 DFPF treated with either DP or a single distal femur locking plating (DFLP). Patients with simple 33-A1 fractures were excluded. Prior to 2018, patients underwent DFLP after which the treatment of choice became DP.

OUTCOME MEASURES AND COMPARISONS

Reoperation rate, alignment, and complications.

RESULTS

34 patients treated with DFLP and 38 with DP met inclusion and follow up criteria. Average follow up was 18.2 ± 13.8 months in the DFLP group and 19.8 ± 16.1 months in the DP group ( P = 0.339). The average patient age in the DFLP group was 74.8 ± 7.3 years compared to 75.9 ± 11.3 years in the DP group. There were no statistical differences in demographics, fracture morphology, loss of reduction, or reoperation for any cause ( P >.05). DP patients were more likely to be weight bearing in the twelve-week postoperative period ( P <0.001) and return to their baseline ambulatory status ( P = 0.004) compared to DFLP patients.

CONCLUSIONS

Dual plating of distal femoral periprosthetic fractures maintained coronal alignment with a low reoperation rate even with immediate weight bearing and these patients regained baseline level of ambulation more reliably as compared to patients treated with a single distal femoral locking plate.

LEVEL OF EVIDENCE

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

Does the type of medial plate fixation matter for supplemental fixation of distal femur fractures manage with a lateral pre-contoured locked plate? A Biomechanical study

INTRODUCTION

Fixation of distal femur fractures with a lateral pre-contoured locking plate provides stable fixation and is the standard treatment in most cases, allowing early range of motion with a high rate of union. However, in situations, the stability achieved with the lateral plate alone may be insufficient, predisposing to fixation failure. The objective of the study was to compare, in synthetic bone models, the biomechanical behaviour of the fixation with a distal femur lateral pre-contoured locking plate solely and associated with a 3.5 mm proximal humeral locking plate applied upside down or a 4.5 mm helical locking compression plate on the medial side.

MATERIAL AND METHODS

A total of 15 solid synthetic left femur samples were used. A metaphysical defect at the level of the medial cortex was simulated. The samples were randomly distributed into three groups equally. All groups received a 4.5/5.0 mm single lateral 9-hole distal femur lateral pre-contoured locking plate. Group 1 had no supplementary plate. Group 2 received a supplementary 6-hole 3.5 mm proximal humeral locking plate and Group 3 received a supplementary 4.5/5.0 mm helical 14-hole narrow locking compression plate.

RESULTS

Both supplementary plate types used in groups 2 and 3 contributed to increase the apparent stiffness of the construct, but pairwise comparison showed statically significant difference only between group 1 and 3. No significant difference was observed between groups 2 and 3.

CONCLUSION

Both supplementary plates might be considered for improving the fixation in distal femur fracture in selected cases.

Combined nail-plate constructs in the management of osteoporotic native distal femoral fractures: a systematic review of the available evidence

PURPOSE

Distal femoral fractures account for 4-6% of fragility fractures. These may be managed using a combined nail-plate construct (NPC). The use of NPCs is gaining traction. Whilst several theoretical advantages exist, there is little evidence reporting on binary or patient-reported outcomes. The aim of the current study was to perform a systematic review of the available literature pertaining to NPCs and their treatment of native distal femoral fractures, appraising the outcomes and focusing on the rationale for their increasing uptake in recent literature.

METHODS

A comprehensive search of MEDLINE, EMBASE, Clinical Key, PubMed and Cochrane library was performed from date of inception up to in August 9, 2022. All study languages were included initially. A further Google Scholar search review was performed to identify any other studies not identified in the database interrogation. Studies were eligible if they reported on the use of nail-plate constructs in managing distal femoral fractures. Any outcome metric was permitted. The study was conducted in accordance with PRISMA guidelines. Risk of bias was assessed using the Methodological Index for non-randomised Studies tool. Quantitative analysis was performed using a log odds ratio random effects model. The Knapp-Hartung adjustment was utilised if the total number of included studies was < 5. Study effect sizes and appropriate plots were constructed to illustrate the outcomes data.

RESULTS

A total of four studies were eligible for inclusion. Study data was extracted and summarised with their relevant outcomes presented. The literature review demonstrated that the use of NPCs led to significantly earlier full weight bearing (p < 0.001) and had reduced non-union rates over a single construct, without affecting infection rates (12.5% vs. 5.6%; p = 0.289) and significantly lower implant failure rates (10.5% vs. 0%; p = 0.011). A meta-analysis is performed of available studies and Forrest plots presented.

CONCLUSION

The use of NPC in the management of native osteoporotic DFFs is gaining traction but the available evidence is of low grade with significant heterogeneity in small cohorts of patients. We suggest that a large-scale, multicentre prospective study should be performed, with agreed functional and radiological outcome metrics, to provide a more robust evidence base.

Biomechanical analysis of bridge combined fixation system as a novel treatment for the fixation of type A3 distal femoral fractures

Background

To compare the biomechanical parameters of AO/OTA type A3 distal femoral fractures fixed bilaterally with a bridge combined fixation system (BCFS) and lateral locking compression plate + locking reconstruction plate (LCP + LRP).

Methods

Twelve A3 distal femoral fracture models with medial cortical defects of the distal femur were created using synthetic femoral Sawbones. BCFS and LCP + LRP were used for bilateral fixation, with six in each group. Axial compression and torsion tests were performed on the two groups of fracture models to determine their stiffness during axial compression and the Torsional stiffness during torsion tests. Axial compression failure tests were performed to collect the vertical loads of the ultimate failure tests.

Results

In the test conducted on the fixed type A3 distal femoral fracture models, the axial stiffness in the BCFS group (group A) (1,072.61 ± 113.5 N/mm) was not significantly different from that in the LCP + LRP group (group B) (1,184.13 ± 110.24 N/mm) (t = 1.726, P = 0.115), the Torsional stiffness in group A (3.73 ± 0.12 N.m/deg) was higher than that in group B (3.37 ± 0.04 N.m/deg) (t = 6.825, P < 0.001),and the ultimate failure test of type A3 fracture model showed that the vertical load to destroy group A fixation (5,290.45 ± 109.63 N) was higher than that for group B (3,978.43 ± 17.1 N) (t = 23.28, P < 0.05). Notably, intertrochanteric fractures occurred in groups A and B.

Conclusions

In the fixation of type A3 distal femoral fractures, the anti-axial compression of the BCFS group was similar to that of the LCP + LRP group, but the anti-torsion was better.

Nail Plate Combination Fixation Versus Lateral Locked Plating for Distal Femur Fractures: A Multicenter Experience

OBJECTIVES

To (1) report on clinical, radiographic, and functional outcomes after nail-plate fixation (NPF) of distal femur fractures and (2) compare outcomes after NPF with a propensity matched cohort of fractures treated with single precontoured lateral locking plates.

DESIGN

Multicenter retrospective cohort study.

SETTING

Ten Level 1 trauma centers.

PATIENTS/PARTICIPANTS

Patients with OTA/AO 33A or 33C fractures.

INTERVENTION

Fixation with (1) retrograde intramedullary nail combined with lateral locking plate (n = 33) or (2) single precontoured lateral locking plate alone (n = 867).

MAIN OUTCOME MEASUREMENTS

The main outcomes of interest were all-cause unplanned reoperation and presence of varus collapse at final follow-up.

RESULTS

One nail-plate patient underwent unplanned reoperation excluding infection and 2 underwent reoperation for infection at an average of 57 weeks after surgery. No nail-plate patients required unplanned reoperation to promote union and none exhibited varus collapse. More than 90% were ambulatory with no or minimal pain at final follow-up. In comparison, 7 of the 30 matched lateral locked plating patients underwent all-cause unplanned reoperation excluding infection (23% vs. 3%, P = 0.023), and an additional 3 lateral locked plating patients were found to have varus collapse on final radiographs (10% vs. 0%, P = 0.069).

CONCLUSIONS

Despite a high proportion of high-energy, open, and comminuted fractures, no NPF patients underwent unplanned reoperation to promote union or demonstrated varus collapse. Propensity score matched analysis revealed significantly lower rates of nonunion for NPF compared with lateral locked plating alone. Larger studies are needed to identify which distal femur fracture patients would most benefit from NPF.

LEVEL OF EVIDENCE

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

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.

Clinical Application of Nail-Plate Fixation in the Treatment of Complex Proximal Third Humeral Fracture: A Case Report and Literature Review

BACKGROUND

Proximal humeral fractures with increasing incidence are common over the past decades. Among them, the complicated and displaced ones, especially combined with the proximal third humeral shaft fractures, need to be treated surgically. Humeral intramedullary nail and locking plate are the most frequently used options. However, few studies address the application of nail-plate combination for management.

CASE PRESENTATION

A 49-year-old man struck by a car was referred to our emergency trauma center. The X-ray and three-dimensional computed tomography (CT) showed a complex proximal humeral fracture with proximal third shaft fracture. No evidence of other associated injuries and neurovascular symptom of the injured left upper limb was shown by physical examination. Nail-plate fixation was performed to restore the anatomic integrity of proximal humerus. The injured arm was maintained in a broad arm sling for 14 days after surgery. The active as well as positive movements under the instruction were encouraged as long as the pain could be tolerated from postoperative day 2. One year after the surgery, the fracture was healed, and the patient regained normal shoulder motion. The good clinical outcomes were obtained by application of nail-plate fixation to treat complex proximal third humeral shaft fractures. Thus, this surgical intervention could be performed as an alternative.

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.

Effect of Implant Linkage on Axial and Rotational Stiffness of Nail-Plate Constructs for Comminuted Distal Femoral Fractures

OBJECTIVES

To determine the effect of linking the intramedullary nail and the laterally applied locking plate to treat comminuted distal femur fractures and allow for immediate weight bearing.

METHODS

Comminuted extra-articular distal femur fractures were created in 16 synthetic osteoporotic femurs and split into 2 groups: linked versus unlinked. In the linked construct, in addition to standard plate fixation and proximal locking of the nail, 2 nonthreaded locking bolts (prototypes) were placed through both the plate and the nail. In the unlinked construct, the same number of screws affixed the plate to the bone but were directed around the nail, and separate distal interlocking screws were placed for nail fixation. Each specimen underwent sequential axial and torsional loading, and axial and torsional stiffness were calculated and compared.

RESULTS

On average, the unlinked constructs demonstrated a greater axial stiffness at all levels of axial loading, and linked constructs demonstrated greater average rotational stiffness. However, there were no statistically significant differences ( P > 0.189) between the linked and unlinked groups at any axial or torsional load.

CONCLUSION

In distal femur fractures with metaphyseal comminution, there were no significant differences in axial or torsional stiffness when linking the plate to the nail. Linking the construct seems to provide no significant mechanical advantage compared with the unlinked environment, but it may be a useful strategy to reduce nail "traffic" in the distal segment with no significant disadvantage.

Three-dimensional computed tomography mapping techniques in the morphometric analysis of AO/OTA 33A and 33C distal femoral fractures: a retrospective single-center study

Purpose: Complex distal femoral fractures involve a challenging set of considerations that must be known to provide optimal management. This study aimed to determine the location and frequency of fracture lines and comminution zones in AO/OTA types 33A and 33C distal femoral fractures using three-dimensional computed tomography mapping. Methods: Seventy-four consecutive eligible patients were included. Fracture fragments for each patient were reconstructed, virtually reduced, and adjusted to match the distal femoral template. Then, all fracture lines and comminuted areas were extracted in transparent mode, and corresponding heat maps were constructed. Finally, these maps, along with the quantitative analysis findings of the counts and volumes of each fragment, were used to summarize the characteristics of the fractures. Results: Thirty-four females and 40 males [average age, 58 years (range, 18-92 years)] presented with a distal femoral fracture. There were 53 AO/OTA type 33A fractures, and 21 AO/OTA type 33C fractures. These two patterns differed significantly on fracture fragment count, comminuted zone fracture fragment count, and mean comminuted zone fracture fragment volume (p < 0.05). Most of the fracture line heat zones were in the femoral epiphysis, intercondylar notch of the femur, and patellofemoral joint. The comminuted area heat regions were mostly found on the lateral, anterior, and posterior femoral diaphysis, with less involvement on the medial side. Conclusion: Our findings may serve as a guide for the surgical approach selection of complex distal femur fractures, the placement strategy of the internal fixation, and the optimization of the osteotomy plan for biomechanical studies.

Management of Non-union Distal Femur Fractures With Augmentation Nail Plate Construct

Background and objective A non-union distal femur fracture is a challenging fracture to treat. Common treatment modalities for non-union distal femur fractures include dual plating, intramedullary nails, ilizarov, and hybrid fixators. Despite the availability of a wide armamentarium of constructs, the clinical and functional outcome of these modalities is often complicated by significant morbidity, joint stiffness, and delayed union. The augmentation of the intramedullary nail with a locking plate results in a robust architecture, improving the likelihood of union. The use of this nail plate construct improves biomechanical stability and restores limb alignment, which enables early rehabilitation and weight bearing and lowers the likelihood of fixation failure. Methodology A prospective study was conducted at the Government Institute of Medical Science, Greater Noida, from January 2021 to January 2022 on 10 patients with non-union of the distal femur. All the patients were operated on with nail plate construct. The minimum follow-up period was 12 months. Results A total of 10 patients with a mean age of 55 years were included. Six were earlier treated with an intramedullary nail and four with extramedullary implants. All patients were managed with implant removal and fixation with nail plate construct and bone grafting. The average duration of the union was 10.3 months. The International Knee Documentation Committee (IKDC) score improved from 30.6 preoperatively to 67.3 postoperatively. Only one patient developed a superficial infection, which was managed by wound debridement and targeted antibiotic therapy. Conclusion In our experience, this relatively novel technique of combining nail plate constructs offers encouraging outcomes in the management of non-union of distal femur fractures, especially in elderly and osteopenic patients.

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.

Orthogonal plating of distal femur fractures: A biomechanical comparison with plate-nail and parallel plating constructs

Purpose

This study compared the biomechanical properties of orthogonal plating with plate-nail and parallel plating constructs for supracondylar distal femur fractures.

Methods

A supracondylar distal femur fracture was simulated using 15 synthetic osteoporotic femurs. Constructs included: (1) plate-nail (lateral locked distal femoral plate + retrograde intramedullary nail); (2) parallel plating (lateral locked distal femoral plate + medial 4.0 mm compression plate); and (3) orthogonal plating (lateral locked distal femoral plate + posterior one-third tubular plate). Specimens underwent nondestructive loading, fatigue loading, and loading to failure. Gapping at the fracture was measured using a three-dimensional motion capture system. Baseline torsional and axial stiffness, stiffness and strain after fatigue loading, and load to failure were determined. A case example of orthogonal plating is also presented.

Results

There was no difference in baseline torsional (p = 0.51) and axial stiffness (p = 0.53). Stiffness after fatigue loading was highest with parallel plating, with no difference between the plate-nail and orthogonal plating constructs (p = 0.84). Strain after fatigue loading was lowest in the parallel plating group (0.54 ± 0.19%), followed by the plate-nail (2.89 ± 0.83%) and orthogonal plating groups (3.04 ± 0.51%).

Conclusion

Orthogonal plating demonstrated comparable baseline stiffness to plate-nail and parallel plating constructs, and similar biomechanical performance in fatigue loading to plate-nail constructs. All specimens had ≤3% strain after fatigue loading, suggesting sufficient stability for fracture healing. The benefits of enhanced stability from dual-implant fixation may be achieved through orthogonal plating while avoiding an additional medial surgical approach, and therefore warrants further investigation as a novel alternative for distal femur fracture fixation.

Medial and lateral dual plating of native distal femur fractures: a systematic literature review

Introduction

Lateral locked plating (LLP) development has improved outcomes for distal femur fractures. However, there is still a modest rate of nonunion in fractures treated with LLP alone, with higher nonunion risk in high-energy fractures, intra-articular involvement, poor bone quality, severe comminution, or bone loss. Several recent studies have demonstrated both the safety and the biomechanical advantage of dual medial and lateral plating (DP). The purpose of this study was to evaluate the clinical outcomes of DP for native distal femoral fractures by performing a systematic review of the literature.

Methods

Studies reporting clinical outcomes for DP of native distal femur fractures were identified and systematically reviewed. Publications without full-text manuscripts, those solely involving periprosthetic fractures, or fractures other than distal femur fractures were excluded. Fracture type, mean follow-up, open versus closed fracture, number of bone grafting procedures, nonunion, reoperation rates, and complication data were collected. Methodologic study quality was assessed using the Coleman methodology score.

Results

The initial electronic review and reverse inclusion protocol identified 1484 publications. After removal of duplicates and abstract review to exclude studies that did not discuss clinical treatment of femur fractures with dual plating, 101 potential manuscripts were identified and manually reviewed. After final review, 12 studies were included in this study. There were 199 fractures with average follow-up time of 13.72 months. Unplanned reoperations and nonunion occurred in 19 (8.5%) and 9 (4.5%) cases, respectively. The most frequently reported complications were superficial infection (n = 6, 3%) and deep infection (n = 5, 2.5%) postoperatively. Other complications included delayed union (n = 6, 3%) not requiring additional surgical treatment and knee stiffness in four patients (2%) necessitating manipulation under anesthesia or lysis of adhesions. The average Coleman score was 50.5 (range 13.5-72), suggesting that included studies were of moderate-to-poor quality.

Conclusions

Clinical research interest in DP of distal femoral fractures has markedly increased in the past few decades. The current data suggest that DP of native distal femoral fractures is associated with favorable nonunion and reoperation rates compared with previously published rates associated with LLP alone. In the current review, DP of distal femoral fractures was associated with acceptable rates of complications and generally good functional outcomes. More high-quality, directly comparable research is necessary to validate the conclusions of this review.

Cerebral Palsy: Current Concepts and Practices in Musculoskeletal Care

Cerebral palsy is a neurologic disorder characterized by a spectrum of motor and cognitive deficits resulting from insults to the developing brain. The etiologies are numerous and likely multifactorial; an increasing portion of cases may be attributable to genetic causes, although the exact mechanisms responsible remain poorly understood. Major risk factors include intrauterine stroke and prematurity and neonatal infection, trauma, and hypoxia, which may occur in the prenatal, perinatal, or postnatal period. The Gross Motor Function Classification System (GMFCS) is a widely used tool to establish a child's level of function and to guide treatment; however, additional metrics are necessary to formulate long-term prognoses. Goals of care are to maximize function and independence, which directly correlate with overall quality of life, and family participation is key to establishing goals early in treatment. Nonpharmaceutical treatments include physical, occupational, and speech therapy, as well as bracing, equipment, and technology. There is a breadth of medical interventions for managing hypertonia, including medications, botulinum toxin injections, intrathecal baclofen pumps, and selective dorsal rhizotomy. Orthopedic interventions are indicated for symptomatic or progressive musculoskeletal sequelae. Treatments for dysplastic hips and/or hip instability range from soft tissue releases to bony procedures. Neuromuscular scoliosis is managed with posterior spinal fusion because bracing is ineffective against these rapidly progressive curves. The degree of care varies considerably depending on the child's baseline GMFCS level and functional capabilities, and early screening, diagnosis, and appropriate referrals are paramount to initiating early care and maximizing the child's quality of life.

Biomechanical and anatomical considerations for dual plating of distal femur fractures: a systematic literature review

INTRODUCTION

Distal femur fractures are challenging injuries historically associated with high rates of nonunion and varus collapse with operative management. As a result, clinical and research interest in dual plating (DP) of distal femur fractures has seen a dramatic increase in recent years. The purpose of this study was to systematically review the literature regarding vascular anatomy and biomechanics of distal femur fractures treated with DP constructs.

MATERIALS AND METHODS

A systematic literature review of two medical databases (PubMed & Scopus) was performed to identify peer-reviewed studies on the anatomy and biomechanics regarding DP of distal femur fractures. A total of 1,001 papers were evaluated and 14 papers met inclusion criteria (6 anatomy and 8 biomechanics). Methodological quality scores were used to assess quality and potential bias in the included studies.

RESULTS

In the biomechanical studies, DP constructs demonstrated greater axial and rotational stiffness, as well as less displacement and fewer incidences of failure compared to all other constructs. Vascular studies showed that the femoral artery crosses the mid-shaft femur approximately 16.0-18.8 cm proximal to the adductor tubercle and it is located on average 16.6-31.1 mm from the femoral shaft at this location, suggesting that medial plate application can be achieved safely in the distal femur. The methodological quality of the included studies was good for biomechanical studies (Traa score 79.1; range 53-92.5) and excellent for anatomical studies (QUACs score 81.9; range 69.0-88.5).

CONCLUSIONS

Existing biomechanics literature suggests that DP constructs are mechanically stronger than other constructs commonly used in the treatment of distal femur fractures. Furthermore, medial distal femoral anatomy allows for safe application of DP constructs, even in a minimally invasive fashion. Dual plating should be considered for patients with distal femur fractures that have risk factors for instability, varus collapse, or nonunion.

Plate configuration for biological reconstructions of femoral intercalary defect - a finite element evaluation

BACKGROUND AND OBJECTIVE

Biological reconstruction was commonly used for femoral intercalary defect. The initial stability by plate fixation was believed to have an effect on bone union and implant failure. Our study was proposed to explore relationship of plate configuration and initial stability for femoral intercalary reconstruction using allo-/autograft.

METHODS

Femoral intercalary defect models were established with four different plate configurations: (1) Single lateral bridging plate, SLP (2) Lateral bridging plate + Orthogonal adjuvant plate, LP+OAP (3) Lateral bridging plate + Medial adjuvant plate, LP+MAP (4) Lateral bridging plate + Medial bridging plate, LP+MP. A diaphysis defect of 12 cm was simulated, and the removed native femoral bone was used as a structural allograft with the osteotomy gap of 2 mm. Models were analyzed by finite element simulations under an axial compression of 2000N and an axial moment of 10 Nm, respectively.

RESULTS

Axial load: (1) The peak von Mises stress of SLP, LP+OAP, LP+MAP, LP+MP were 993.50 MPa, 335.63 MPa, 240.03 MPa, 281.73 MPa, respectively and LP+MAP was the lowest (p < 0.01); (2) The mean displacement of SLP, LP+OAP, LP+MAP, LP+MP was 0.765, 0.130, 0.121, 0.235 mm, respectively. LP+MAP showed the best stability while SLP had a crash in the medial proximal gap; (3) The LP+MAP configuration had the most uniform stress distribution and the lowest maximum von Mises stress of 79.7 MPa within plates. Axial torsional load: (1) The peak von Mises stress of SLP, LP+OAP, LP+MAP, LP+MP were 431.66Mpa, 120.73 MPa, 72.31 MPa, 109.86 MPa, respectively; (2) The rotation angle of SLP, LP+OAP, LP+MAP, LP+MP was 4.30°, 1.35°, 1.20°, 1.57°, respectively. All of LP+OAP, LP+MAP and LP+MP showed an optimal torsional stability.

CONCLUSIONS

For femoral intercalary reconstruction using allo-/autograft fixed by plates, LP+MAP and LP+MP configurations showed superior stability in terms of axial compression and torsion load by FE simulation. A better stability was believed to be associated with higher union rate and lower hardware failure rate.

Proximal tibia and tibial plateau nail-plate combinations: technical trick and case series

Proximal tibia fractures and combined tibial shaft-plateau injuries are increasingly common. Prolonged nonweightbearing may result in poor outcomes, particularly in elderly patients. Nail-plate combination constructs offer an attractive solution to facilitate early weight-bearing in these complex problems. We describe strategies and tips for these constructs and present the results of a small patient series treated with this technique.

Distal femoral replacement or internal fixation for management of periprosthetic distal femur fractures: A systematic review

BACKGROUND

The number of periprosthetic fractures above a total knee arthroplasty continues to increase. These fractures are associated with a high risk of morbidity and mortality. Techniques for addressing these fractures include open reduction internal fixation (ORIF) and revision arthroplasty, including distal femoral replacement (DFR). The primary aim of this review is to compare mortality and reoperation rates between ORIF and DFR when used to treat periprosthetic distal femur fractures.

METHODS

A systematic review including MEDLINE, Embase and Cochrane Library databases was completed from inception to April 10, 2021. Studies including a comparator cohort were meta-analyzed.

RESULTS

Fourteen studies were identified for inclusion, of which, five had sufficient homogeneity for inclusion in a meta-analysis. 30-day and 2-year mortality was 4.1% and 14.6% in the DFR group. There was no statistically significant difference between ORIF and DFR (log Odds-Ratio (OR) = -0.14, 95 %CI: -0.77 to 0.50). The reoperation rate in the DFR group was 9.3% versus 14.8% for ORIF, with no difference between groups (log OR = 0.10, 95 %CI: -0.59 to 0.79). There was no difference in rates of deep infection (log OR = 0.22, 95 %CI: -0.83 to 1.28). Direct comparison of functional outcomes was not possible, though did not appear significant.

CONCLUSION

DFR in the setting of periprosthetic distal femur fractures is equivalent to ORIF with respect to mortality and reoperation rate and thus a safe and reliable treatment strategy. DFR may be more reliable in complex fracture patterns where the ability to obtain adequate fixation is difficult.

Fixation of Extra-articular Proximal Tibia Fractures: Biomechanical Comparison of Single and Dual Implant Constructs

OBJECTIVES

This biomechanical study seeks to define the relative effectiveness of contemporary single and dual implant constructs for fixation of an extra-articular proximal tibia fracture model.

METHODS

An extra-articular proximal tibia fracture model was created using synthetic tibias. Four constructs were tested. Constructs included (1) lateral locked plate (LLP), (2) intramedullary nail (IMN), (3) combined LLP and IMN (PN), and (4) LLP and medial locked plate. Specimens were axially loaded through the medial plateau to evaluate construct stiffness and the ability to resist varus collapse.

RESULTS

Dual implant constructs were stiffer than single implant constructs in this model. Although DP and PN were stiffer than IMN at all loads tested, the difference was notable only for DP at higher loads. Isolated LLP provided insufficient stability to be tested at higher loads.

CONCLUSION

Dual plate fixation provides the greatest resistance to varus collapse. In the clinical setting, consideration must be given to the fracture morphology, desired construct stiffness, and soft-tissue envelope in selecting the optimal construct to be used.

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.

Double fixation for complex distal femoral fractures

For complex distal femoral fractures, a single lateral locking compression plate or retrograde intramedullary nail may not achieve a stable environment for fracture healing.

Various types of double fixation constructs have been featured in the current literature. Double-plate construct and nail-and-plate construct are two common double fixation constructs for distal femoral fractures.

Double fixation constructs have been featured in studies on comminuted distal femoral fractures, distal femoral fracture with medial bone defects, periprosthetic fractures, and distal femoral non-union.

A number of case series reported a generally high union rate and satisfactory functional outcomes for double fixation of distal femoral fractures.

In this review, we present the state of the art of double fixation constructs for distal femoral fractures with a focus on double-plate and plate-and-nail constructs.

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

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.

Failure of dual plating in a complex open distal femur fracture as the result of major trauma

A 61-year-old polytrauma patient was admitted with a right distal comminuted metaphyseal femoral fracture with intra-articular extension (Orthopaedic Trauma Association 33C2.3 classification) among other injuries. Due to the high degree of comminution and massive bone loss, this was initially managed with a dual plating open reduction internal fixation. Dual plating has shown to be a superior fixation method than single variable angle locking compression plate (VA-LCP) plating providing greater fixation in metaphyseal bone. Our case reports the failure of dual plating which required removal of metalwork and subsequent fixation using intramedullary nail and plate technique. Failure of dual plating is not well documented in the literature. The most recent radiographs taken 15 months postrevision surgery show that the bone has started to heal with evidence of callus formation.

Impact on periosteal vasculature after dual plating of the distal femur: a cadaveric study

Although dual plating of distal femur fractures has been described for injuries at risk of varus displacement, the vascular insult to the medial distal femur utilizing this technique is unknown. The aim of this study was to evaluate the perfusion of the medial distal femoral periosteal arteries after supplemental medial plating of the distal femur.

Methods

Fifteen human fresh-frozen cadaveric femora were thawed and randomized to lateral locked plating alone or with supplemental medial plate fixation. Conventional submuscular medial plating was performed using a 12-hole small fragment plate and multiple cortical screws. The superficial femoral artery was injected with latex dye. Specimens were dissected. The patency of the medial distal femoral periosteal vessels was evaluated.

Results

Four vessels were consistently observed traversing the distal medial femur: the transverse and descending (d-MMPA) branches of the medial metaphyseal periosteal artery, and the transverse and longitudinal branches of the descending geniculate artery. The anterior longitudinal arch (ALA) was present in 13 of 15 specimens and was fed by the d-MMPA. The median number of periosteal arteries occluded by the medial plate was 2 (6 out of 8 specimens). The d-MMPA was occluded in 6 of 8 medially plated femurs, resulting in a complete lack of perfusion of the ALA.

Conclusions

Submuscular medial plating of the distal femur compressed the d-MMPA in the majority of specimens. This vessel gives rise to the ALA, which lacked perfusion in these specimens. This vascular insult could affect the healing of metaphyseal distal femur fractures treated with dual plating.

Maintaining the Neutral Axis in the Treatment of Distal Femur Fractures Via Dual Plate or Nail Plate Combination Technique: When and How?

SUMMARY

Distal femur fractures in the elderly have been historically treated with locked plating or retrograde intramedullary nailing with good, reliable results. However, in certain more complex fracture patterns (native or periprosthetic), increased density of fixation via dual-plate or nail plate combination can help achieve immediate weight-bearing. It can also potentially increase rates of union by shifting and maintaining the neutral axis, distributing forces more evenly across the fracture site. Here, we discuss the indications, pros and cons of both dual-plate and nail plate combination techniques in a concise case-based format.

Biomechanics of Osteoporotic Fracture Care: Advances in Locking Plate and Intramedullary Nail Technology

Osteoporotic fractures are extremely common and will continue to increase. Methods of internal fixation must address challenges presented by architectural changes of weakened bone. The goals of surgery are to provide mechanically stable internal fixation with minimal biologic insult that provides rapid rehabilitation and early mobilization. Novel techniques and technology that reinforce preservation of periosteal blood supply and utilization of biomechanically stable constructs diminish failure rates. Advents in locking plate technology, intramedullary nail designs, bone augmentation, and multiple implant constructs maximize strength while mitigating axial, torsional, and bending failure modes to provide optimal patient outcomes.

Optimal Fixation of the Capitellar Fragment in Distal Humerus Fractures

OBJECTIVES

To determine if orthogonal or parallel plate position provides superior fixation of the separate capitellar fragment often present in intra-articular distal humerus fractures. We hypothesized that orthogonal plating would provide stiffer fixation given a greater number of opportunities for capitellar fixation and screw trajectories perpendicular to the fracture plane offered by a posterolateral plate compared with a parallel plate construct.

METHODS

Ten matched pairs of cadaveric distal humeri were used to compare parallel and orthogonal plating in a fracture gap model with an isolated capitellar fragment. The capitellum was loaded in 20 degrees of flexion using a cyclic, ramp-loading protocol. Fracture displacement was measured using video tracking software. The primary outcome was axial stiffness for each construct. Secondary outcomes included maximum axial and angular fracture displacement.

RESULTS

The parallel plate construct was more than twice as stiff as the orthogonal plate construct averaged across all loads (1464.8 ± 224.0 N/mm vs. 526.3 ± 90.8 N/mm, P < 0.001). Average axial fracture displacement was 0.15 ± 0.03 mm versus 0.53 ± 0.10 mm for parallel versus orthogonal plating, respectively (P = 0.003). Angular fracture displacement was minimal for both constructs (0.009 ± 0.001 degrees vs. 0.028 ± 0.006 degrees for parallel vs. orthogonal constructs).

CONCLUSIONS

Despite fewer points of fixation, a parallel plate construct provided stiffer fixation with less displacement of the simulated capitellar fracture fragment than an orthogonal plate construct in this biomechanical study. In the setting of an articular fracture, in which absolute stability and primary bone healing are desirable, parallel fixation should be considered even in fractures with a separate capitellar fragment if the size of fragment and fracture orientation allows.

Supplemental medial small fragment fixation adds stability to distal femur fixation: A biomechanical study

INTRODUCTION

Bridge plating of distal femur fractures with lateral locking plates is susceptible to varus collapse, fixation failure, and nonunion. While medial and lateral dual plating has been described in clinical series, the biomechanical effects of dual plating of distal femur fractures have yet to be clearly defined. The purpose of this study was to compare dual plating to lateral locked bridge plating alone in a cadaveric distal femur gap osteotomy model.

MATERIALS AND METHODS

Gap osteotomies were created in eight matched pairs of cadaveric female distal femurs (average age: 64 yrs (standard deviation ± 4.4 yrs); age range: 57-68 yrs;) to simulate comminuted extraarticular distal femur fractures (AO/OTA 33A). Eight femurs underwent fixation with lateral locked plates alone and were matched with eight femurs treated with dual plating: lateral locked plates with supplemental medial small fragment non-locking fixation. Mechanical testing was performed on an ElectroPuls E10000 materials testing system using a 10 kN/100 Nm biaxial load cell. Specimens were subject to 25,000 cycles of cyclic loading from 100-1000 N at 2 Hz.

RESULTS

Two (2/8) specimens in the lateral only group failed catastrophically prior to completion of testing. All dual plated specimens survived the testing regimen. Dual plated specimens demonstrated significantly less coronal plane displacement (median 0.2 degrees, interquartile range [IQR], 0.0-0.5 degrees) compared to 2.0 degrees (IQR 1.9-3.3, p = 0.02) in the lateral plate only group. Dual plated specimens demonstrated greater bending stiffness compared to the lateral plated group (median 29.0 kN/degree, IQR 1.5-68.2 kN/degree vs median 0.50 kN/degree, IQR 0.23-2.28 kN/degree, p = 0.03).

CONCLUSION

Contemporary fixation methods with a distal femur fractures are susceptible to mechanical failure and nonunion with lateral plates alone. Dual plate fixation in a cadaveric model of distal femur fractures underwent significantly less displacement under simulated weight bearing conditions and demonstrated greater stiffness than lateral plating alone. Given the significant clinical failure rates of lateral bridge plating in distal femur fractures, supplemental fixation should be considered, and dual plating of distal femurs augments mechanical stability in a clinically relevant magnitude.

[Clinical application of lower extremity axial distractor in closed reduction and retrograde intramedullary nail fixation of distal femoral fractures]

Objective

To explore the efficacy and advantages of the lower extremity axial distractor assisted closed reduction and retrograde intramedullary nail internal fixation in the treatment of distal femoral fractures.

Methods

The clinical data of 49 patients with distal femoral fractures treated with retrograde intramedullary nail internal fixation between April 2016 and December 2018 were retrospectively analyzed. According to the different methods of intraoperative reduction, the patients were divided into trial group (29 cases, using lower extremity axial distractor to assist closed reduction) and control group (20 cases, using free-hand retraction reduction). There was no significant difference in general information between the two groups ( P>0.05), such as gender, age, side of injury, cause of injury, and fracture classification. The operation time, intraoperative blood loss, intraoperative fluoroscopy frequency, and callus formation time were recorded and compared between the two groups. The function of the affected limb was evaluated according to the Schatzker-Lambert standard at 1 year after operation.

Results

All patients successfully completed the operation. In the control group, there was 1 case with open reduction and internal fixation, and the rest of the two groups were closed reduction. There was no significant difference in operation time, intraoperative blood loss, and intraoperative fluoroscopy frequency between the two groups ( P>0.05). There was no complication such as vascular or nerve injury and iatrogenic fracture, etc. during and after operation, and the incisions healed by first intention. Except for 2 patients in the trial group who were lost to follow-up at 3 months after operation, the rest of the patients were followed up 12-36 months, with an average of 16.0 months. There was no significant difference in the callus formation time between the two groups ( t=2.195, P=0.145). During the follow-up, postoperative knee joint stiffness occurred in 1 case in the control group, which improved by strengthening the knee joint function exercise and removing the internal fixator; the rest were not found to be associated with delayed or nonunion fractures, knee stiffness, and internal fixation complication. The function of the affected limb was evaluated according to the Schatzker-Lambert standard at 1 year after operation, the trial group achieved excellent results in 22 cases, good in 4 cases, and fair in 1 case, with an excellent and good rate of 96.3%; in the control group, the results were excellent in 16 cases, good in 3 cases, and fair in 1 case, with an excellent and good rate was 95.0%; showing no significant difference in the excellent and good rate between the two groups ( χ ²=0.451, P=0.502).

Conclusion

The lower extremity axial distractor assisted closed reduction and retrograde intramedullary nailing for the treatment of distal femoral fractures is convenient, which has satisfactory efficacy.

Nail plate combination in the upper extremity: surgical technique and clinical application

Nail plate constructs (NPC) have shown promising results in complex lower extremity peri-articular fractures as well as in peri-prosthetic fractures. The combination of both implants allows for improved mechanical stability and immediate weight bearing. The use of NPC has not been described in the upper extremity in the literature. We herein describe potential indications and surgical technique for NPC usage for complex upper extremity trauma and reconstruction.

Extreme Nailing or Less Invasive Plating of Lower Extremity Periarticular Fractures

Periarticular fractures of the lower extremity can be difficult injuries to stabilize effectively. Modern advances in technique and implant design now allow many of these fractures to be fixed with an extreme intramedullary nail. When nailing is not possible, less invasive plating through percutaneous incisions is a reliable option. The decision to perform extreme nailing is multifactorial and is based on the fracture pattern, the condition of the soft tissues, the medical condition of the patient, and the importance of earlier or immediate weightbearing.

Technical Trick: Dual Plate Fixation of Periprosthetic Distal Femur Fractures

Treatment of periprosthetic distal femur fractures remains challenging due to assuring adequate distal fixation. Traditional treatment options include lateral locked plating and retrograde nailing, although recently dual implant constructs have been explored with promising results. Allowing immediate weight-bearing in this patient population has benefits with regards to rehabilitation and outcome. Recent literature has focused on nail-plate constructs, however plate-plate constructs are preferred at our institution as they do not require arthroplasty component compatibility, facilitate the coronal plane reduction, and allow for immediate weight-bearing.

Distal locking of short cephalomedullary nails decreases varus collapse in unstable intertrochanteric fractures - a biomechanical analysis

INTRODUCTION

Peritrochanteric fractures are a growing problem and complications relating to operative fixation of these fracture, including varus collapse and screw cutout, are common in elderly osteoporotic patients. We hypothesize that unlocked nails will demonstrate increased varus collapse and inferior construct stiffness in specimens with increased diaphyseal medullary diameter.

MATERIALS AND METHODS

Sixteen non-cadaveric osteoporotic biomechanical femur specimens were utilized in this study, with eight specimens having an artificially large femoral canal to represent Dorr C femurs. All femurs were instrumented with a short cephalomedullary nail with and without distal cross-lock screw fixation and had an unstable intertrochanteric fracture created in a repeatable pattern. Specimens underwent cyclic compression to a maximal load of 1000N with segmental motion quantified through the use of visual tracking markers. Statistical comparisons were performed using one-way ANOVA with Tukey post-hoc analysis to determine differences between specific groups. Significance was defined as p<0.05.

RESULTS

Unlocked short cephalomedullary nails showed increased varus collapse due to motion of the nail within the femoral canal in capacious femoral canals compared with narrow femoral canals and distally cross-locked nails. The coronal deformation of the wide canal unlocked group (17.9 ^o±2.6^o) was significantly greater in the varus direction than any other fixation under compressive load of 1000N. There was no significant difference in varus angulation between the wide canal or narrow canal locked groups (11.1^o±8.7^o vs. 8.2^o±1.7^o respectively, p=0.267). The narrow canal unlocked group (13.7^o±2.4^o) showed significantly greater varus angulation than the narrow canal locked (p=0.015). The wide canal unlocked group showed significantly greater varus angulation than the wide canal locked group (p=0.003). Motion between the femoral shaft and the cephalomedullary nail (toggling of the nail within the shaft) was significantly greater in narrow or wide canal unlocked specimens, 7.94^o±2.13^o and 10.2^o±1.7^o respectively, than in the narrow or wide canal locked specimens, 2.4^o±0.2^o and 4.2^o±0.5^o respectively (p<0.05) CONCLUSION: Unlocked short intramedullary fixation for unstable peritrochanteric fractures results in increased varus collapse under axial compression. This study supports the use of distal cross-locking of short intramedullary fixation for unstable peritrochanteric fractures in patients with capacious femoral canals secondary to osteoporosis who might otherwise be as risk for varus collapse, device failure, and malunion.