Biomechanical comparison of locked plating and spiral blade retrograde nailing of supracondylar femur fractures

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.

Fractures of the distal femur in elderly patients: retrospective analysis of a case series treated with single or double plate

Introduction

We evaluated the radiologic and clinical outcomes of a lateral incision single plate with and a single-incision double plating in elderly patients with osteoporotic distal femoral fractures.

Materials and methods

We performed a retrospective study of 82 cases of distal femoral fractures from May 2004 to June 2018. Group A consisted of 42 patients who underwent single-plate fixation. Group B consisted of 40 patients who underwent double-plate fixation. The mean patient age was 77 years (67–87 years) and 76 years (64–86 years) in groups A and B, respectively. All patients were evaluated for procedure duration, time to union, range of knee motion, Lysholm knee score, and presence of complications.

Results

The average procedure time was 81 min (66–92 min) and 110 min (95–120 min) in groups A and B, respectively (p = 0.33). One case in group B required bone grafting after 5 months. The average time to union was 14 weeks (9–19 weeks) and 12.2 weeks (8–19 weeks) (p = 0.63), and the mean range of knee motion was 105° (90–125°) and 110.7° (90°–130°) (p = 0.37) in groups A and B, respectively. There was no significant statistical difference between the two groups in the Lysholm knee score (p = 0.44) and knee society score (p = 0.53).

Conclusion

The clinical and radiological outcomes were similar in the 2 groups. In elderly patients, double plate fixation for distal femoral fractures is an useful method for several advantages such as adequate exposure, easy manipulation, anatomical reduction and stable fixation.

[Distal femoral fractures in geriatric patients : Does time to surgery affect revision and mortality?]

BACKGROUND

For proximal femoral fractures the time to surgery has been reported to influence the mortality rate. To date, detailed analyses in geriatric patients with distal femoral fractures are not available.

MATERIAL AND METHODS

A monocentric study with retrospective data retrieved from an electronic database was performed. The study included distal femoral fractures with surgical treatment between 2006 and 2017 in patients aged 65 years and older. A total of ten variables were evaluated and two outcome measures were investigated: revision and mortality in relation to time of surgery within 24 h or later. The minimum follow-up was 2 years. For patients who were still alive the Parker score was calculated. The null hypothesis was that time to surgery does not affect revision and mortality.

RESULTS

A total of 57 consecutive patients with 60 fractures and an average age of 82.5 years (65-97 years) were included. Most of the fractures were supracondylar (n = 42). All but three fractures were treated with internal fixation. The revision rate was 17.5% (peri-implant fractures n = 4, infections n = 2, non-union n = 2, impaired wound healing n = 2 and secondary dislocation n = 1). The 1‑year mortality rate was 20%. No significant effects on revision (p = 0.414) and survival rate (log rank 0.175) were observed for patients treated within 24 h or later. After a mean postoperative period of 5.5 years, the mean Parker score for 18 living patients was 5.9.

CONCLUSION

Time to surgery demonstrated no significant effects with respect to revision and mortality. Multicenter studies are absolutely necessary to increase the sample size and statistical power.

The Old Supracondylar Fracture of Femur Treated by Gradual Deformity Correction Using the Ilizarov Technique Followed by the Second-Stage Internal Fixation in an Elderly Patient With Osteoporosis

Background:

The supracondylar nonunion of femur in elderly individuals is rare and challenging to manage. Nothing in English literatures or guidelines is available regarding this particular fracture characterized by osteoporosis, soft-tissue contracture, shortening, and joint stiffness. We report a case of an elderly patient with a supracondylar nonunion of the femur, which was successfully treated using staged Ilizarov techniques and dual plating.

Case Presentation:

An 84-year-old female patient was admitted to our orthopedic department for her pain and soft-tissue swelling around the right knee with claudication and shortening deformity of the affected extremity. She denied any specific history of trauma and had sought traditional Chinese medical attention for 6 months before she presented to our hospital. Diagnosis of the right femoral supracondylar nonunion was made based on the X-ray and computed tomography. Ilizarov external fixator was carried out for successive and slow distraction and gradual correction of the shortening deformity, in consideration of the nonunion was still present. Subsequently, internal fixation with dual plating of the distal femur was performed. Excellent function and patient satisfaction were observed at 6 months of follow-up.

Conclusion:

The protocol of Ilizarov technique with subsequent internal fixation of dual plating seems to be an efficient solution to the supracondylar nonunion of femur in elderly patients with osteoporosis. The advantage of the protocol is that it allows knee joint motion, avoids neurovascular complications, and gentle correction of soft-tissue contractures.

Comparative analysis of the biomechanical behavior of anterograde/retrograde nailing in supracondylar femoral fractures

Supracondylar femoral fractures account for a noticeable percentage of the femoral shaft fractures, affecting two etiological groups: high energy trauma in young men, with good bone quality, and older women with osteoporotic femur. Surgical treatment of those kind of fractures remains controversial, with different surgical options such as plate and sliding barrel locking condylar plate, less invasive stabilization system (LISS) or intramedullary nailing, which has emerged as a new fixation choice in the treatment of that type of fractures. The present work performs a comparative study about the biomechanical behavior of anterograde and retrograde nailing in supracondylar femoral fractures type A, in order to determine the best choice of nailing and locking configuration. A three-dimensional finite element model of the femur was developed, modeling femoral supracondylar fracture and different nailing configurations, both for anterograde and retrograde nails. The study was focused on the immediately post-operative stage, verifying the appropriate stability of the osteosynthesis. The obtained results show a better biomechanical behavior for anterograde nails, providing a better stability from the point of view of global movements, lower stresses in screws, and less stress concentration in cortical bone. So, for the analyzed fractures and osteosyntheses types, anterograde nailing has demonstrated to be a better surgical option, being an excellent indication in supracondylar fractures of femur, with clear benefits compared to retrograde nailing, providing a better stabilization which enables for a more satisfactory fracture healing.

Dual Plating of the Distal Femur: Indications and Surgical Techniques

Dual-plating of the distal femur is required in some cases to achieve stable fixation. The indications of a medial plate in addition to the lateral plate are medial supracondylar bone loss, low trans-condylar bicondylar fractures, medial Hoffa fracture, peri-prosthetic distal femur fractures, non-union after failed fixation with single lateral plate, poor bone quality and comminuted distal femur fractures (AO type C3). We recommend orthogonal plate configuration with locked plates by a single incision or dual incision approach as per surgeon choice.

Comparison of Less Invasive Stabilization System Plate and Retrograde Intramedullary Nail in the Fixation of Femoral Supracondylar Fractures in the Elderly: A Biomechanical Study

Objective

To compare the biomechanical stabilities of less invasive stabilization system (LISS) plate and retrograde intramedullary nail (IMN) for the comminuted femoral supracondylar fracture fractures in the elderly.

Methods

Sixteen pairs of embalmed cadaver femurs were obtained to simulate a comminuted supracondylar femur fracture (AO/OTA33‐A3) gap model. All left‐side specimens were fixed with LISS plate, and retrograde IMN were applied to the right‐side specimens. All specimens were tested in torsional, axial and cyclic load mode on an Instron testing machine.

Results

The mean torsional stiffness for LISS plate group was 34.1% greater than retrograde IMN group (2.90 vs. 1.91 Nm/degree, P = 0.002), but the mean axial stiffness was greater for the retrograde IMN (199.16 vs. 303.93 N/mm, P < 0.001). The total deformation of LISS plate caused by cyclic axial loading was greater than retrograde IMN (4.17 vs. 3.57 mm, P = 0.014). Significantly less mean irreversible deformation was detected in LISS plate than in retrograde IMN (1.64 vs. 1.69 mm, P = 0.699). Failure loads of the constructs were significantly different between the two groups (LISS plate: 2941±128 N; retrograde IMN: 4022±176 N, P < 0.001).

Conclusion

For comminuted femoral supracondylar fractures in the elderly, the tested instruments can both maintain sufficient biomechanical stabilities, but retrograde IMN is superior to LISS plate in deformation of fracture site.

Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices

Objectives

Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs.

Methods

Synthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests.

Results

The method of loading was found to affect the gap stiffness strongly (by up to six times) but also the magnitude of the plate stress and the location and magnitude of strains at the bone-screw interface.

Conclusions

This study demonstrates that the method of loading is responsible for much of the difference in reported stiffness values in the literature. It also shows that previous contradictory findings, such as the influence of working length and very large differences in failure loads, can be readily explained by the choice of loading condition.

Cite this article: A. MacLeod, A. H. R. W. Simpson, P. Pankaj. Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices. Bone Joint Res 2018;7:111–120. DOI: 10.1302/2046-3758.71.BJR-2017-0074.R2.

A double-plating approach to distal femur fracture: A clinical study

BACKGROUND

Locked plating is one of the latest innovative options for treating supracondylar femur fractures with relatively low failure rates. Single lateral plating was often found to have a relative higher failure rate. No clinical studies of double-plating distal femur fixation have thus far been reported. The aim of this study is to present our clinical experience with this surgical approach.

PATIENTS AND METHODS

Thirty-two patients (26 females and 6 males, mean age 76 years, range 44-101) were included in the study. Eight of them patients had a periprosthetic stable implant fracture and two patients were treated for a nonunion.

RESULTS

All fractures, excluding one that needed bone grafting and one refracture, healed within 12 weeks. One patient needed bone grafting for delayed union and one patient needed fixation exchange due to femur re-fracture at the site of the most proximal screw. Two patients developed superficial wound infection and one patient required medial plate removal after union due to deep infection.

CONCLUSIONS

Based on these promising results, we propose that the double-plating technique should be considered in the surgeon's armamentarium for the treatment of supracondylar femur fractures, particularly in patients with poor bone quality, comminuted fractures and very low periprosthetic fractures.

Retrograde dynamic locked intramedullary nailing for aseptic supracondylar femoral nonunion after dynamic condylar screw treatment

OBJECTIVE

Supracondylar femoral nonunions after dynamic condylar screw (DCS) treatment are uncommon, and few studies have addressed an optimal treatment technique for this disorder. Re-insertion of a new plate may not be secure because of bony defects in the distal fragment, created by the lag screw of the DCS.

MATERIALS AND METHODS

Forty-two consecutive adult patients with 42 supracondylar femoral nonunions were treated with removal of the DCS, re-alignment of the knee axis, and insertion of a retrograde dynamic traditional femoral locked nail. When necessary, a humeral plate was augmented to reinforce rotational stability.

RESULTS

A final group of 36 patients with 36 nonunions were followed for an average of 2.8 years (range 1.1-6.2 years). All nonunions healed with a union rate of 100 %, and the average time to union was 4.2 months (range 2.5-5.5 months). Complications included two malunions. There were no instances of nonunion or deep infection. Satisfactory knee function among 36 patients improved from 8.2 % preoperatively to 86.1 % at the last follow-up (p < 0.001). All 36 patients could walk without aids.

CONCLUSION

The described technique may be an excellent alternative treatment for an aseptic supracondylar femoral nonunion after DCS treatment. The technique is not difficult, and the union rate and satisfactory rate are high.

Do elderly patients fare worse following operative treatment of distal femur fractures using modern techniques?

BACKGROUND

The purpose of this study was to compare the functional outcomes and quality of life of older and younger patients with similarly treated distal femur fractures.

METHODS

We conducted an assessment of 57 patients who sustained distal femur fractures (Orthopaedic Trauma Association Type 33B, C) and underwent surgical treatment at our academic medical center. Patients were divided into 2 groups for analysis: an elderly cohort of patients aged 65 or older and a comparison cohort of patients younger than age of 65. A retrospective review of demographics, preoperative ambulatory status, radiographic data, and physical examination data was collected from the medical records. Follow-up functional data were collected via telephone at a mean of 2.5 years (range 6 months-8 years) using a Short Musculoskeletal Functional Assessment (SMFA). All patients underwent standard operative treatment of either nail or plate fixation.

RESULTS

There was no statistical difference in gender, fracture type, surgical technique, surgeon, or institution where the surgery was performed. The percentage of patients with healed fractures at 6-months follow-up was not significantly different between the cohorts. The elderly cohort had slightly worse knee range of motion at 3, 6, and 12 months postoperatively but there was not a statistically significant difference between the groups. The SMFA Daily Activity, Functional, and Bother indices were significantly worse in the older cohort (P < .01, P = .01, P = .02, respectively). However, there was no significant difference in the SMFA Emotional or Mobility indices.

CONCLUSION

Despite lower quality of life and functional scores, this study suggests that relatively good clinical outcomes can be achieved with surgical fixation of distal femoral fractures in the elderly patients. Age should not be used as a determinate in deciding against operative treatment of distal femur fractures in the elderly patients.