Mechanical strength of intramedullary pinning and transfragmental Kirschner wire fixation for Colles' fractures

Comparative Biomechanical Analysis of Kirschner Wire Fixation in Dorsally Displaced Distal Radius Fractures

OBJECTIVE

This study aims to evaluate and compare the biomechanical performance of two Kirschner (K) wire configurations-the intra-focal and interfragmentary techniques-for the fixation of dorsally displaced distal radius fractures. The study also assesses the impact of K-wire diameter (1.6 mm vs. 2.0 mm) on mechanical stability.

METHODS

Sixty fresh turkey tarsometatarsus bones were selected and divided into four groups based on the K-wire configuration and diameter used. Fractures were created at standardized locations, and each bone was stabilized using either the intra-focal also known as modified Kapandji (Ka) or interfragmentary technique. Mechanical testing, including axial compression and flexion tests, was performed to assess the biomechanical stability of each configuration.

RESULTS

The interfragmentary configuration consistently demonstrated superior biomechanical performance compared to the intra-focal technique. Specifically, the use of 2.0 mm K-wires resulted in significantly higher axial stiffness (13.28 MPa) and load at break (3070 N) compared to the 1.5 mm wires. Confidence intervals further supported the robustness of these findings. The interfragmentary technique, especially with thicker K-wires, provided greater load-bearing capacity and stiffness.

CONCLUSION

The interfragmentary technique with 2.0 mm K-wires offers superior mechanical stability compared to the intra-focal technique, making it the preferred choice for stabilizing comminuted extra-articular distal radius fractures. These findings suggest that adopting this technique may reduce the risk of postoperative complications such as fracture displacement or malunion. Further research involving osteoporotic bone models and clinical trials is recommended to validate these findings in real-world settings.

Kirschner Wire Fixation in Dorsally Displaced Distal Radius Fractures: A Biomechanical Evaluation

Background  There is currently no consensus for the optimum configuration and number of Kirschner wires (K-wires) to use for the stabilization of dorsally displaced distal radius fractures. In this biomechanical study, we compared the load to failure and stiffness of four common K-wire configurations to identify the strongest construct for use in extra-articular dorsally displaced distal radius fractures. Case Description  We created a standard distal radius fracture model in turkey tarsometatarsi which was stabilized using two or three K-wires (1.6 mm) in four different configurations. Following a power calculation, 10 fracture models of each configuration underwent testing in cantilever bending and axial compression. Literature Review  Recent randomized trials have shown no evidence that volar locking plates are superior to K-wires for the treatment of dorsally displaced distal radius fractures. This has led to an increase in the popularity of much cheaper K-wires. Several different K-wire techniques have been described but there is no strong evidence to determine which is the optimal configuration and number of wires. Clinical Relevance  The three-wire interfragmentary configuration was stiffer than the three-wire Kapandji in axial compression and cantilever bending. There was no difference in load to failure in cantilever bending or axial compression. The three-wire interfragmentary technique is the stiffest configuration of K-wires for dorsally displaced distal radius fractures. The two-wire Kapandji technique was significantly weaker than the other configurations, especially in cantilever bending. Conclusion  The authors recommend to always use three wires for percutaneous pinning and never to use two intrafocal wires alone.

Comparison of five percutaneous pinning methods for unstable extra-articular distal radius fractures: A mechanical study using sawbones

Objectives

This study aims to mechanically compare five different extra-focal bi-cortical pin configurations (using two and three pins) employed for fixation of a simulated unstable extra-articular distal radius fracture with dorsal comminution using a sawbone model.

Materials and methods

This in vitro mechanical study was conducted between June 2019 and July 2019. A standard fracture model (Arbeitsgemeinschaft für Osteosynthesefragen [AO] type 23-A3.3) was created using a fourth generation composite artificial radius bone. Five groups with two- and three-pin configurations were tested under axial, volar, and dorsal loading with a universal test device. Mean stiffness values were compared statistically.

Results

Comparison of stiffness values from axial and volar loading tests between groups in paired comparison showed no statistically significant difference (p=0.194 and p=0.086, respectively). Dorsal loading tests showed statistically significant difference between the groups in pairwise comparison (p=0.002). Three-pin groups (Groups 3, 4, and 5) had higher stiffness values compared to two-pin groups (Groups 1 and 2) in dorsal loading tests (p=0.001). Three-pin configuration test groups with two divergent or convergent pins from the radial styloid performed better compared to both two-pin groups (p=0.01, p=0.002) in dorsal loading tests.

Conclusion

Our data demonstrated that the three-pin configuration with two divergent or convergent Kirschner wires from the styloid and a third wire from the dorsal/ulnar cortex had higher stiffness values compared to two-pin configurations in dorsal loading tests. When indicated, we suggest the use of a three-pin construct. Particularly in cases with a risk of volar angulation, we recommend a three-pin configuration with two divergent or convergent bi-cortical Kirschner wires.

[Over-reduction after distal radius fracture pinning in young active patients: Prevention by multiple mixed pinning]

Over-reduction is a classical complication following pinning of distal radius fractures. Indeed, the pinning techniques derived from Kapandji's technique do not allow anterior stabilization. A literature review and our experience show that it is an underestimated complication that can affect up to one-third of cases, but that is well tolerated if the anterior tilt is less than 20°. Excessive angulation of the dorsal intrafocal K-wires becomes a significant risk factor beyond 60°. Volar comminution of the fracture is an obvious predisposing factor. We will outline our ideas on the topic and present a new pinning technique, which has reduced the over-reduction rate to below 3 %: multiple mixed pinning combines two dorsal intrafocal K-wires with two trans-styloid K-wires along the anterior and posterior cortices of the radius to provide true sagittal stabilization of the fracture. This technique is suitable for fractures without major instability or associated anterior comminution-Milliez types 1 and 2 are its best indications. In our practice, there still is a place for pinning of non-complex fractures in young active subjects. More than 20° malunion in flexion can lead to symptoms; in this instance, isolated opening osteotomy of the radius is the most suitable technique.

Dorsally displaced distal radius fractures: comparative study of Py's and Kapandji's techniques

INTRODUCTION

Within the framework of a regional clinical study, the radiographic results of Py's and Kapandji's fixation techniques for dorsally displaced distal radius fractures were compared.

PATIENTS AND METHODS

A prospective randomised monocenter and multi-operator study (phase III clinical trial) comparing the Py's (isoelastic pinning) and Kapandji's (intrafocal pinning) techniques was conducted. Two comparable groups were established: the Py (P) and Kapandji (K) groups. The frontal radial tilt (FRT), sagittal radial tilt (SRT), radial length and ulnar variance were measured. Analysis of subjective and objective function was based on the range of motion according to six parameters, the DASH and Jakim scoring systems. The quality of anatomical restoration was assessed arthroscopically during pin removal at 6 postoperative weeks.

RESULTS

Ninety-seven patients were included in the study with a follow-up period of 1 year. The preoperative FRT was 15.17° and SRT was -19.2°. At one-year follow-up, the FRT was 25.5° in the PY group and 22.6° in the K group (p=0.009), the SRT was 10.5° in the PY group and 6.7° in the K group (p=0.04). For fractures with postero-medial fragment and Gerard Marchand's fractures, the DASH score at last follow-up was 22 in the Py group, 42 and 32 respectively in the K group. The Jakim score was 71 in the PY group and 58 in the K group (p=0.03) for fractures with postero-medial fragment. There was no report of tendon rupture in our study.

DISCUSSION

Besides the good results achieved with both pinning techniques in the treatment of distal radius fractures, this series also underlines the importance to adapt the type of fixation to the fracture pattern and patient.

CONCLUSION

Pinning for treating dorsally displaced distal radius fractures appears a suitable option provided that the indications and the surgical technique for each method are respected. However, pinning is not suitable for all types of fractures.

LEVEL OF EVIDENCE

Level II. Randomised prospective therapeutic study.

BIOMECHANICAL EVALUATION OF PLATE OSTEOSYNTHESIS FOR AO TYPE C2 FRACTURE OF THE DISTAL RADIUS — A CADAVER STUDY

An AO type C2 distal radius fracture was simulated in a cadaver model by creating a metaphyseal defect of 5 mm and an intra-articular defect of 2 mm. Five different methods of plate osteosynthesis were tested biomechanically in each of six fresh cadaveric hands. Biomechanical testing suggested that cement augmented plating plus screws in the distal fragment was the strongest. Dorsal and volar plating plus screws on both sides of the distal fragment had the same effect of restoring stiffness and load transmission pattern as fixation with double plating plus volar screws alone. Fixation with plating plus dorsal screws was significantly weaker than these three methods, and double buttress plating with no screws in the distal fragments was the weakest.

MECHANICAL STUDY ON DORSAL STABILITY OF INTRAMEDULLARY OSTEOSYNTHESIS ASSOCIATED WITH EXTERNAL FIXATION (ULSON'S METHOD)

Objective: To evaluate the Ulson intramedullary fixation method, with external fixation in which the level of the external locking of the Kirschner wires is varied, and without external fixation. Methods: Eighteen porcine tibias were used. Transverse osteotomy was performed in the region of the tuberosity, and two intramedullary Kirschner wires were inserted into each specimen, using three different assembly patterns: Group I: locking with external minifixator at a height of 3.0 cm; Group II: locking at a height of 4.5 cm; Group III: without external locking. Mechanical shear tests were then conducted, to determine the maximum load, proportionality limit and coefficient of rigidity. Results: There were no significant differences in maximum load or proportionality limit between the groups. The coefficient of rigidity was higher in Group II. Conclusion: The locking height for the Kirschner wires in Ulson's method, within the limits evaluated, did not harm the stability of the fracture fixation system.

Stability of volar locking plate systems for AO type C3 fractures of the distal radius: biomechanical study in a cadaveric model

BACKGROUND

The purpose of the present study was to compare the relative stability of five volar locking plates (all of which are available for the treatment of intraarticular fractures of the distal radius) under loading conditions simulating the physiological forces that occur during early active mobilization.

METHODS

Five plating techniques were applied to surgically simulated AO type C3.2 distal radius fractures in formalin-fixed cadavers. The specimens were tested with a servohydraulic materials testing machine with 250 N of axial compression load for 3000 cycles. After cyclic loading, the specimens were loaded until they demonstrated failure in axial compression. The five fixation systems studied included a DRV locking plate (group 1), a Stellar plate (group 2), an Acu-Loc plate (group 3), AO Locking Distal Radius System 2.4 (group 4); and a Matrix SmartLock plate (group 5).

RESULTS

None of the plate fixations tested failed during the cyclic loading. Group 2 had a higher elastic limit than groups 4 and 5. There were no significant differences among the five groups for the failure load. Failure occurred at the distal portion of the fixation system, at the ulnar side locking pin, or the locking screw was bent (groups 1, 2, 3); the ulnar side locking screw was broken (groups 3, 4); the locking screw became loose (group 4); and the ulnar side locking screw was uncoupled from the screw hole (group 5).

CONCLUSIONS

All of the five volar plate fixation systems provided sufficient stability to permit 3000 repeated motions of the digits after surgery for AO type C3 distal radius fractures.

Solitary giant hemangioma of the humerus

Osseous hemangiomas are mainly seen in the skull or spine and rarely occur in other bones. They are small lesions usually localized in the metaphyseal and diaphyseal regions. This article describes a rare case of a giant intraosseous hemangioma occupying nearly the whole humerus for 28 years. Initially, the patient, a 36-year-old woman, had been misdiagnosed with fibrous hyperplasia of the left humerus. We intended to curette the lesions and transplant fibula to fill the bone defect, but the initial surgical attempt could not be completed due to massive intraoperative bleeding. In the second surgery, she was treated by blocking the blood flow of the subclavian artery temporarily through a balloon catheter, curetting lesions, and filling the defect of bone with bone cement and K-wires. At 12-month follow-up, there was no evidence of local recurrence of hemangioma or loosening of bone cement. However, longer-term follow-up is needed to confirm the success of the surgery. Although hemangiomas of long bone are rare, they should be considered in the differential diagnosis of bone tumors.

[Dynamic biomechanical study of a new osteosynthesis system for distal radius fractures]

The aim of this study was to evaluate the stability in compression of a new implant for fractures of the distal radius. Of all the displacements found with this fracture, shortening is the one most difficult to maintain by osteosynthesis. We tested the properties of a central-medullary steel nail 9 cm length, of diameter 5 mm, curvilinear, introduced at the radial styloid, combining proximal unicortical and distal bicortical locking. The biomechanical laboratory tests were carried out on 10 human radii taken from 5 male anatomical subjects of ages ranging from 48 to 88 years. A wedge-shaped defect in the metaphyseal zone was created to reproduce posterior shortening in these Pouteau-Colles' fractures. The same anatomical subject received the two types of osteosynthesis: an intramedullary nail and a styloid pinning. The force-displacement curves showed that intramedullary osteosynthesis with this interlocking nail is an assembly three times more resistant to compression than bi-styloid pinning. Stabilization of this fracture in porotic bone has to rely on distal screw purchase in the subchondral bone, which seems to us to be the only element able to resist compressive forces. This new implant should make it possible to restore and preserve the length of the radius whilst maintaining reduction in all three dimensions. Given its good biomechanical results, this nail constitutes a viable possibility for minimally invasive internal fixation of these fractures and warrants a clinical trial.

Biomechanical stability of a fixed-angle volar plate versus fragment-specific fixation system: cyclic testing in a C2-type distal radius cadaver fracture model

PURPOSE

To compare the biomechanical stability of 2 recently introduced fixation systems in an intra-articular, dorsal comminution distal radius fracture model.

METHODS

AO/ASIF type C2 fractures were simulated in 10 matched pairs of fresh-frozen cadaveric arms randomized between fixed-angle volar plate and fragment-specific fixation systems. Specimens were loaded in extension cyclically for 2,000 repetitions followed by a single cycle to failure. Initial, intermediate, and final stiffness values and failure load values were obtained and compared.

RESULTS

Both systems were able to sustain physiologic cyclic loading. The fragment-specific system was significantly stiffer than the fixed-angle volar plate system for the ulnar segment in both the precycle and postcycle values. No other comparisons were significant with respect to stiffness. No significant difference in load to failure was found between the systems with respect to ulnar, radial, or overall fragment displacement.

CONCLUSIONS

Both fixed-angle volar plate and fragment-specific fixation systems performed comparably in a simulated early postoperative motion protocol. Fragment-specific fixation had improved stiffness characteristics only with respect to the smaller ulnar-sided fragment.

Complications encountered while using thin-wire-hybrid-external fixation modular frames for fracture fixation. A retrospective clinical analysis and possible support for "Damage Control Orthopaedic Surgery"

One hundred ninety eight adult patients who had sustained long bone fractures were treated by external fixation from admission to bone healing and consolidation. Of these, 135 had sustained high-energy injuries, 39 of them had suffered multi-system injuries. Superficial pin track infection was the most common complication, occurring predominantly in pins located in the femur, upper tibia and upper humerus. There were no cases of deep infection or osteomyelitis. One patient with a femoral shaft fracture developed a DVT although he was on preventive low molecular weight heparin, i.e. sc Clexane 40 mg daily. There were no cases of PE or ARDS. External fixation systems are a minimal invasive surgical modality, which allow three-dimensional fracture fixation after closed or minimal open reduction. They require a good command of surgical anatomy, but provide an optimal preservation of the fracture's soft tissue envelope, the critical biological factor for new bone formation and fracture healing. Recent publications have suggested that in the critically ill patient, minimally invasive fracture fixation surgery may prevent the perpetuation of a reactive, life threatening inflammatory reaction (the "second hit") which may induce the development of multiple organ dysfunction (MODS).

Biomechanics in uniaxial compression of three distal radius volar plates

PURPOSE

A new fixed-angle volar plate for a dorsally displaced distal radius fracture was designed with the aim of avoiding soft tissue problems due to dorsal plating. The purpose of this study was to compare the biomechanical properties of this new plate with 2 existing volar plates in a cadaver model.

METHODS

Three different plates were applied on surgically simulated unstable extra-articular distal radius fractures in formalin-fixed cadaver radiuses. Group 1 (volarly placed AO titanium Distal Radius plates [Synthes Ltd, Paoli, PA]; n = 6), group 2 (volarly placed titanium Symmetry plates [DePuy ACE Co, El Segundo, CA]; n = 6), and group 3 (volarly placed newly designed titanium plates; n = 6) were tested to failure under axial compression with a materials testing machine. Specimens of all 3 groups had similar bone mineral density.

RESULTS

Group 3 specimens had significantly greater elastic limit and ultimate strength than the other 2 groups. Specimens of group 3 had the greatest rigidity, although this was statistically insignificant compared with the other 2 groups. All plates (groups 1, 2, 3) failed in apex volar angulation.

CONCLUSIONS

The newly designed plate fixation system is the strongest of the systems tested and may offer adequate stability for the treatment of a distal radius fracture in which the dorsal and/or volar metaphyseal cortex is comminuted severely.

A cadaveric model for biomechanical study of fixation methods for AO type C2 fractures of distal radius: design and testing with dorsal plating fixation

Fracture of the distal radius is a common injury. Functional recovery correlates well with restoration of anatomy and early motion. Various fixation methods have been proposed to achieve this. To evaluate the stability of different treatment options, a cadaveric model for biomechanical study of fixation methods for AO type C2 fracture of distal radius was designed and its efficacy assessed in the present experiment.