Bicortical screw fixation of distal fibula fractures with a lateral plate: an anatomic and biomechanical study of a new technique

Mini-Blade Plate to Obtain Length Across Lateral Malleolus Fractures: Surgical Technique and Biomechanical Evaluation

BACKGROUND

Restoration of fibular length is the main determinant in preventing mal-union and early ankle arthritis in lateral malleolus fractures. A 1/3 tubular plate fashioned into a mini-blade plate can be used to distract the distal fragment and achieve length in a controlled fashion over time. The purpose of this study was to describe the surgical technique and perform a biomechanical comparison of the blade plate to a locking plate.

METHODS

A 1/3 tubular plate is fashioned into a 135° blade plate. Blades are seated into the lateral malleolus and a distally directed force is applied on the plate to obtain length.A lateral malleolus fracture was created in 20 cadaveric ankles. The distal fragment was fixed with either a blade plate (BP, n = 10) or a locking plate (LP, n = 10). A distally directed force was applied by an Instron machine and fracture distraction, maximal load and construct stiffness were measured and compared.

RESULTS

The average maximal load was 262.06 N compared to 255.52 N for the BP and LP groups, respectively. The maximal distraction was 3.57 mm compared to 4.57 mm for the BP and LP groups, respectively. The loading pattern of the blade plate over time differed from that of a locking plate as the blades seat into bone.

CONCLUSION

A 1/3 tubular mini-blade plate demonstrates biomechanical similarities in terms of load and distraction to the more expensive locking plate. We recommend using this technique for fractures with late presentation or with significant shortening.

LEVEL OF EVIDENCE

Level V-Mechanism-based reasoning.

Twisted Plating - A Method of Distal Fibula Fixation

Objective  The literature entails various intramedullary and extramedullary methods for distal fibula fracture fixation; with no consensus yet over the ideal method of fixation. We have retrospectively analyzed the results of using a twisted and contoured 3.5 mm locking compression plate (LCP) as a posterior buttress plate. Methods  Of the 62 cases with ankle fractures managed at our institute by the senior author from 1 ^st January 2012 to 31 ^st December 2015, 41 patients met our inclusion criteria (Danis-Weber types B and C). Results  All 41 distal fibular fractures healed uneventfully, at a mean of 10.4 weeks (8-14 weeks) (Figs. 6, 7, 8 to 9) with no complications. The mean American Orthopaedic Foot & Ankle Society (AOFAS) score was 92.6 (86-100) at a mean follow-up of 31.5 months (14-61 months). Conclusions  We have achieved excellent clinical and radiological outcomes using a twisted 3.5 mm LCP as a posterior buttress by combining the advantages of posterior antiglide plating and lateral LCP.

Anatomic Feasibility of Distal Fibula Bicortical Screw Fixation With Lateral Neutralization Plating for Rotational Ankle Fractures

A common technique for fixation of rotational fibular fractures is to use an interfragmentary compression screw with a laterally positioned neutralization plate. The objective of the present investigation was to examine the anatomic feasibility of distal fibula bicortical fixation within this plating technique. A specific screw insertion technique was performed through a laterally positioned one-third tubular plate on a consecutive series of 81 intact cadaveric ankle mortises. The most distal plate hole was drilled, aimed 10° posterior to the midline of the fibula. The second-most distal plate hole was drilled, aimed 25° superiorly. The specimens were then dissected, and the screw termini were physically examined for whether they had penetrated the articular cartilage of the ankle mortise. The length of the most distal bicortical screw measured a mean ± standard deviation of 20.44 ± 2.49 (range 14 to 26) mm, with an extra-articular terminus in 95.06% of specimens. The length of the second-most distal bicortical screw measured a mean ± standard deviation of 19.68 ± 3.02 (range 12 to 28) mm, with an extra-articular terminus in 100% of the specimens. The results of the present study provide evidence that bicortical distal fibular fixation in accordance with basic fixation principles is anatomically possible and feasible with a one-third tubular plate. This could potentially obviate the need for more expensive fixation options (i.e., locked plates or anatomically contoured plates) and fixation options that are biomechanically stable but potentially anatomically impeding (i.e., posterior antiglide plating).

Implant Failure Rates and Cost Analysis of Contoured Locking Versus Conventional Plate Fixation of Distal Fibula Fractures

The authors analyzed 330 consecutive Weber B distal fibula fractures that occurred during a 3-year period and were treated with either a contoured locking plate or a conventional one-third tubular plate to compare the cost and failure rates of the 2 constructs. The primary outcomes were failure of the distal fibular implant and loss of reduction. Secondary outcomes were surgical wound infection requiring surgical debridement and/or removal of the fibular implant, and removal of the fibular plate for persistent implant-related symptoms. No failure of the fibular plates or distal fibular fixation occurred in either group. A total of 5 patients required surgical revision of syndesmotic fixation within 4 weeks of the index surgery. Of these patients, 1 was in the contoured locking plate group and 4 were in the one-third tubular plate group (P=.610). The rate of deep infection requiring surgical debridement and/or implant removal was 6.2% in the contoured locking plate group and 1.4% in the one-third tubular plate group (P=.017). The rate of lateral implant removal for either infection or symptomatic implant was 9.3% in the contoured locking plate group and 2.3% in the one-third tubular plate group (P=.005). A typical contoured locking plate construct costs $800 more than a comparable one-third tubular plate construct. Based on a calculated estimate of 60,000 locking plates used annually in the United States, this difference translates to a potential avoided annual cost of $50 million nationally. This study demonstrates that it is possible to treat Weber B distal fibula fractures with one-third tubular plates at a substantially lower cost than that of contoured locking plates without increasing complications. [Orthopedics. 2017; 40(6):e1024-e1029.].

Distal fibula fracture fixation: Biomechanical evaluation of three different fixation implants

BACKGROUND

The goal of this study was to evaluate the biomechanical performance of three distal fibula fracture fixation implants in a matched pair cadaveric fibula model: (1) a 5-hole compression plate with lag screw, (2) a 5-hole locking plate with lag screw, and (3) the 6-hole tabbed-plate with locking screws.

METHODS

Three-dimensional motions between the proximal and distal fibular segments were measured under cyclic valgus bending, cyclic compressive axial loading, and cyclic torsional external-rotation loading. During loading, strains were measured on the surfaces of each fibula near the simulated fracture site, and on the plate, to assess load transfer. Bone quality was quantified globally for each donor using bone mineral density (BMD) measured using Dual X-ray absorptiometry (DEXA) and locally at the fracture site using bone mineral content (BMC) measured using peripheral quantitative computed tomography (pQCT).

RESULTS

Mean failure loads were below 0.2Nm of valgus bending and below 4Nm of external-rotational torque. Mean failure angulation was below 1degree for valgus bending, and failure rotation was below 7degrees for external-rotation. In the compression plate group, significant correlations were observed between bone quality (global BMD and local BMC) and strain in every one of the five locations (Pearson correlation coefficients >0.95, p<0.05). In contrast, in the locking and tabbed-plate groups, BMD and BMC correlated with far fewer strain locations.

CONCLUSIONS

Overall, the tabbed-plate had similar construct stability and strength to the compression and locking plates. However, the distribution of load with the locking and tabbed-plates was not as heavily dependent on bone quality.

Does a polyaxial-locking system confer benefits for osteosynthesis of the distal fibula: A cadaver study

BACKGROUND

In plate osteosynthesis involving the distal fibula, antiglide plating is superior to lateral plating in terms of the biomechanical properties. The goal of this study was to examine whether polyaxial-locking implants confer additional benefits in terms of biomechanical stability.

METHODS

Seven pairs of human cadaveric fibulae were subjected to osteotomy in a standardized manner to simulate an uncomplicated Weber B fracture. The generated fractures were managed with a dorsolateral antiglide plate. To this end, one fibula of the pair was subjected to non-locking plating and the other to polyaxial-locking plating. Biomechanical tests included quantification of the primary bending and torsional stiffness. In addition, the number of cycles to failure in cyclic bending loading were determined and compared. Bone mineral density was measured in all specimens.

RESULTS

Bone mineral density was comparable in both groups. Primary stability was higher in the polyaxial-locking group under torsional loading, and higher in the non-locking group under bending loading. The differences, however, were not statistically significant. All specimens except for one fixed-angle construct failed the cyclic loading test. The number of cycles to failure did not differ significantly between polyaxial-locking and non-locking fixation.

CONCLUSION

In a cadaveric Weber B fracture model, we observed no differences in biomechanical properties between polyaxial-locking and non-locking fixation using an antiglide plate. Based on the biomechanical considerations, no recommendation can be made regarding the choice of the implant. Further biomechanical and clinical studies are required.

CLINICAL RELEVANCE

Information on the behavior of polyaxial-locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.

Fixation of distal fibula fractures: an update

Level of Evidence:

Level V, expert opinion.

Biomechanical comparison of a lateral polyaxial locking plate with a posterolateral polyaxial locking plate applied to the distal fibula

BACKGROUND

Polyaxial locking plates are becoming popular for the fixation of distal fibula fractures. This study establishes how construct stiffness and plate loosening, measured as range of motion, differs between lateral and posterolateral plate location.

METHODS

Seven matched pairs of cadaver fibulae were osteotomized in standardized fashion to produce a Weber type B distal fibula fracture. The fragments were fixated with an interfragmentary lag screw and polyaxial locking plates, with one fibula in each pair receiving a posterolateral anti-glide-plate, and the other a lateral neutralization-plate. In a biomechanical test, the bending and torsional stiffnesses of the constructs and the ranges of motion (ROM) were measured and subjected to a paired comparison.

RESULTS

The laterally plated group had a higher median (interquartile range) bending stiffness (29.2 (19.7) N/mm) and a smaller range of motion (2.06 (1.99) mm) than the posterolaterally plated group (14.6 (20.6) N/mm, and 4.11 (3.28) mm, respectively); however, the results were not statistically significant (pbending=0.314; pROM=0.325). Similarly, the torsional stiffness did not differ significantly between the two groups (laterally plated: 426 (259) Nmm/°; posterolaterally plated: 248 (399) Nmm/°; ptorsion=0.900). The range of motion measurements between the two groups under torsional loading were also statistically insignificant (laterally plated: 8.88 (6.30) mm; posterolaterally plated: 15.34 (12.64) mm; pROM=0.900).

CONCLUSION

In biomechanical cadaver-model tests of Weber type B fracture fixation with polyaxial locking plates, laterally plated constructs and posterolaterally plated constructs performed without significantly difference. Therefore, other considerations, such as access morbidity, associated injuries, patient anatomy, or surgeon's preference, may guide the choice of plating pattern. Further clinical studies will be needed for the establishment of definitive recommendations.

CLINICAL RELEVANCE

Information on the behavior of polyaxial locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.

Biomechanical comparison of 4 different lateral plate constructs for distal fibula fractures

BACKGROUND

Displaced lateral malleolar fractures are often treated with reduction and surgical stabilization. However, there has not been a comprehensive laboratory comparison to determine the most appropriate device for treating these patients. This study subjected a range of contemporary lateral fibular plates to a series of mechanical tests designed to reveal performance differences.

METHODS

Forty fresh frozen lower extremities were divided into 4 groups. A Weber B distal fibula fracture was simulated with an osteotomy and stabilized using 1 of 4 plate systems: a standard Synthes one-third tubular plate with interfragmentary lag screw, a Synthes LCP locking plate with lag screw, an Orthohelix MaxLock Extreme low-profile locking plate with lag screw, or a TriMed Sidewinder nonlocking plate. Controlled monotonic bending and cyclic torsional loading were applied and bending stiffness, torsional stiffness, and fracture site motion were quantified. Resistance to cyclic torsional loading was determined by quantifying the number of loads withstood before excessive rotation occurred. Correlation between bone mineral density and each of the mechanical measures was determined.

RESULTS

There was no difference in angulation or bending stiffness between plates. All plates except the LCP showed greater lateral deflection than in the other bending directions. Bending stiffness was lowest in lateral distal fragment deflection for all 4 plates. There was a positive correlation between bone mineral density and bending stiffness for all plate types. There was no difference in fracture site rotation between plate types in internal or external torsion, but internal rotation of the distal fragment consistently exceeded external rotation. Torsional stiffness in external rotation exceeded stiffness in internal rotation in nearly all specimens. LCP plates performed relatively poorly under cyclic torsion.

CONCLUSIONS

Significant differences in plate performance were not demonstrated. The effects of bone quality variability and differences in interfragmentary screw purchase resulted in data dispersion that confounded absolute ranking of plate performance.

CLINICAL RELEVANCE

Identification of an optimal lateral fibular plating system has the potential to improve the clinical outcome of malleolar fracture fixation, particularly when patient conditions are unfavorable.

A biomechanical comparison of one-third tubular plates versus periarticular plates for fixation of osteoporotic distal fibula fractures

OBJECTIVES

The purpose of this study was to test the biomechanical properties of locking and nonlocking plates using one-third tubular and periarticular plate designs in an osteoporotic distal fibula fracture model.

METHODS

Twenty-four cadaveric specimens, whose bone mineral densities were obtained using dual x-ray absorptiometry scans, were tested. The fracture model simulated an OTA 44-B2.1 fracture. The constructs included (1) nonlocking one-third tubular plate, (2) locking one-third tubular plate, (3) nonlocking periarticular plate, and (4) locking periarticular plate. The specimens underwent axial loading followed by torsional loading to failure. Statistical analysis was performed using Kruskal-Wallis testing and further analysis with Mann-Whitney testing.

RESULTS

The periarticular plates had greater rotational stiffness compared with the one-third tubular plates (P = 0.04). The nonlocking plates had greater torque to failure than the locking plates (P = 0.01). The nonlocking one-third tubular plate had greater torque to failure than the locking one-third tubular plate (P = 0.03). No significant differences were found in any of the comparisons regarding axial stiffness.

CONCLUSIONS

In biomechanical testing using an osteoporotic model of OTA 44-B2.1 fractures, periarticular plates were superior to one-third tubular plates in rotational stiffness only. Locking plates did not outperform their nonlocking counterparts. Periarticular plates should be considered when treating osteoporotic distal fibula fractures, but one-third tubular plates and nonlocking plates provide adequate fixation for these injuries.

Biomechanical analysis of the impact of fibular osteotomies at tibiotalar joint: A cadaveric study

BACKGROUND

Osteotomy of the fibula is a common orthopedic procedure performed for various indications, including harvesting fibula for grafting purposes. The effect of fibular osteotomy and need for tibiofibular syndesmotic fixation fusion at different levels on tibiotalar joint is matter of debate. We performed a biomechanical analysis of the impact of fibular osteotomies at different levels and whether the fixation of distal tibiofibular joint mitigates instability caused by the osteotomy.

MATERIALS AND METHODS

Six lower limb specimens from fresh adult cadavers were used to prepare leg-foot models. The specimens were assigned to six status according to the level of osteotomy and whether fixation of distal tibiofibular joint was performed or not. Each specimen was then loaded axially to 700 N by the material testing machine, and the tibiotalar joint contact area and peak pressure were measured using an electronic pressure sensor.

RESULTS

The contact area and the pressure of tibiotalar joint showed significant changes when compared to the normal specimen. All osteotomy specimens had a decreased tibiotalar contact area and an increased peak pressure. This positively correlated with proximity of level of osteotomy to the lateral malleolus.

CONCLUSIONS

Through this study, we found that fibular osteotomy had an adverse effect in terms of decreasing the contact surface of tibiotalar joint that led to increased peak pressure in the joint. However, bone fusion and screw fixation of the distal tibiofibular joint reduced these adverse effects.