**7. Clinical and biomechanical studies regarding plates with polyaxial stability for fractures of distal radius and proximal humerus**

Among the elderly, distal radius is the second most common fracture location after hip fractures. Mauck et al. [39] presented a wide variety of fracture patterns. Dorsal and metaphyseal radius fractures are usually treated with closed reduction

*Recent Advances in Biomechanics*

(**Figure 16**).

tered in the XS-nail group.

of the soft tissue interposition.

caused by direct trauma.

recover faster and with better long-term results.

fragments connected by the Kirschner wire [37].

soft tissues due to the intramedullary position.

93.2% of the cases [38] (**Figure 17**).

As a result, an implant that allows compression of the entire fracture surface was needed. To achieve this, the XS nail entitled Tension Band Compression Nail (TCN) was developed and placed centrally in the patella; this implant allows equally distributed compression on the whole surface by muscular distraction [35] (**Figure 15**). In a biomechanical study, the authors divided 30 sawbone patellas into four types of fractures. Proximal third, middle, distal third, and Y-pattern fractures were obtained by osteotomy. Osteosynthesis was carried out using one XS nail, two XS nails, and standard AO tension band. The three-part Y-pattern fractures were fixed with an additional circular wire system (cerclage) in the AO tension band group

Plastic and total deformations were recorded, while the sawbone patellas were submitted to a force of 250 and 500 N at 30°. The batch with XS nail sets the lowest value in the entire lot. The highest deformation occurred in the AO tension band group, and a significant gap appeared between the fragments. No gap was regis-

Smaller differences were recorded in the Y-pattern group based on the strength of the circular wire put in close contact with the bone that was added to the tension band group. We must mention that in real clinical cases this is not possible because

The experimental data show that the XS nail system is a viable alternative to the AO tension band due to its good fixation of the fragments and less deformation under physiological loading. This implant's characteristics will allow patients to

Tension band wiring of olecranon fractures has been the standard choice since 1963. However, migrations of the Kirschner wires and cerclage failure were reported in up to 80% of the cases [36]. Even a numerical model of the tension band wiring technique proved that high von Mises stresses were seen at the bridge between two

The plate osteosynthesis alternative may aggravate a soft tissue lesion, usually

The intramedullary XS nail is a new form of osteosynthesis that allows uniform compression of the fracture surfaces by central positioning the implant. Moreover, increased fixation in the cortical bone can be obtained by locking the 4.5 mm nail with threaded 2.4 mm wires. The surgical technique is easy and protective for the

In a clinical study from 2006, 80 olecranon fractures were treated with XS nail osteosynthesis, and after a follow-up period of 16 months, the results were good in

The XS nail represents, in our opinion, a future possibility in the treatment of olecranon fractures, especially in the elderly population, where bone quality is deficient.

*(A) TCN with locking aiming device; (B) Kirschner wire aiming device; and (C) compression screw* 

**120**

**Figure 15.**

*placement.*

and cast immobilization or K-wire fixation. However, the fracture is most often unstable, and the reduction is not always maintained. Therefore, all unstable fractures or articular fractures have to be treated surgically. Due to the stability deficiency of the osteosynthesis with standard plates, depending on the type of fracture, an additional ventral, dorsal, or even radial fixation with a high degree of complexity is necessary. Studies showed that this type of osteosynthesis was accompanied by complications related to tendons lesions and a high risk of secondary dislocation or angulation.

Since the 1990s, plates with angular stability started to be used more often in the treatment of distal radius fractures. Initially being used for simple metaphyseal fractures, angular stability plates were later used in complex fractures depending on the fracture pattern. Different types of screws had to be adapted to the different articular fragments, which needed to be fixed. Moreover, an articular positioning of the screws had to be avoided, and this was followed by unavoidable issues regarding stability [40].

Thus, multidirectional (polyaxial) plates with multiple angulation possibilities were developed. The screws can be inserted perpendicularly on the plate surface or at an angle of 10° distal/proximal, medial, or lateral, offering the possibility for insertion at plate level in positions very close to the articular surface. Depending on the bone structure and the multiple fracture trajectories, fixation of fracture fragments is always possible in the adequate position (**Figure 18**).

Because these implants require large incisions with soft tissue damage and deperiostation, a new type of implant was developed [41]. The XS radius (XSR) nail is a 4.5- or 3.5-mm straight nail that is introduced after drilling and inserting a guide wire inside the medullary canal. It is then locked using threaded wires in three different directions (**Figures 19** and **20**).

The authors tested the osteosynthesis with angular stable plate and XS nail on 16 osteotomized sawbones that replicate AO/A3 fractures of the distal radius. We registered the deformation after we subjected them to 1000 alternating load cycles from 20 to 200 N (**Figures 21** and **22**).

The experimental study showed a reduced deformation of the XS nail system compared to the plates with angular stability. The deformation amplitude was only 0.31 mm in the XS nail system compared to 0.42 mm in the angular stability plate [41].

Although both implants showed good biomechanical results, the deformation recorded in the XS group proved to be 20% lower than the plate group. The XS nail has the advantages of a simple operation technique, the intraosseous positioning, and saving the pronator quadrates; however, very comminuted fractures are better treated with multidirectional (angular) locking plate [40, 41].

To date, no consensus has been reached regarding the optimal treatment of proximal humerus fractures [42]. Instability and fragment displacement usually require surgical treatment for a better quality of life. Highly comminuted fractures

#### **Figure 18.**

*(A) Polyaxial stability plate; (B and C) AO/C2 type distal radius fracture, carpal scaphoid fracture; (front and lateral view); (D and E) reduction and osteosynthesis of radius fracture with polyaxial stability plate + additional K wires and osteosynthesis of the carpal scaphoid fracture with Herbert screw + K wire.*

**123**

**Figure 21.**

**Figure 19.**

**Figure 20.**

*Clinical and Experimental Biomechanical Studies Regarding Innovative Implants in Traumatology*

*(A) XS nail in sawbone with aiming device and (B) multidirectional locking of the XS nail with threaded K wires.*

*(A) X-ray view of AO/A3 proximal radius fracture and (B) reduction and osteosynthesis with XS nail.*

will necessitate hemi or total shoulder arthroplasty, but the vast majority of fractures can be treated by osteosynthesis with multidirectional angular stability plates

*(A) Angular stable plate and XS nail osteosynthesis and (B) alternating load test.*

or other types of plates (**Figures 23** and **24**).

*DOI: http://dx.doi.org/10.5772/intechopen.91728*

*Clinical and Experimental Biomechanical Studies Regarding Innovative Implants in Traumatology DOI: http://dx.doi.org/10.5772/intechopen.91728*

#### **Figure 19.**

*Recent Advances in Biomechanics*

ary dislocation or angulation.

and cast immobilization or K-wire fixation. However, the fracture is most often unstable, and the reduction is not always maintained. Therefore, all unstable fractures or articular fractures have to be treated surgically. Due to the stability deficiency of the osteosynthesis with standard plates, depending on the type of fracture, an additional ventral, dorsal, or even radial fixation with a high degree of complexity is necessary. Studies showed that this type of osteosynthesis was accompanied by complications related to tendons lesions and a high risk of second-

Since the 1990s, plates with angular stability started to be used more often in the treatment of distal radius fractures. Initially being used for simple metaphyseal fractures, angular stability plates were later used in complex fractures depending on the fracture pattern. Different types of screws had to be adapted to the different articular fragments, which needed to be fixed. Moreover, an articular positioning of the screws had to be avoided, and this was followed by unavoidable issues regarding stability [40]. Thus, multidirectional (polyaxial) plates with multiple angulation possibilities were developed. The screws can be inserted perpendicularly on the plate surface or at an angle of 10° distal/proximal, medial, or lateral, offering the possibility for insertion at plate level in positions very close to the articular surface. Depending on the bone structure and the multiple fracture trajectories, fixation of fracture

fragments is always possible in the adequate position (**Figure 18**).

treated with multidirectional (angular) locking plate [40, 41].

different directions (**Figures 19** and **20**).

from 20 to 200 N (**Figures 21** and **22**).

Because these implants require large incisions with soft tissue damage and deperiostation, a new type of implant was developed [41]. The XS radius (XSR) nail is a 4.5- or 3.5-mm straight nail that is introduced after drilling and inserting a guide wire inside the medullary canal. It is then locked using threaded wires in three

The authors tested the osteosynthesis with angular stable plate and XS nail on 16 osteotomized sawbones that replicate AO/A3 fractures of the distal radius. We registered the deformation after we subjected them to 1000 alternating load cycles

The experimental study showed a reduced deformation of the XS nail system compared to the plates with angular stability. The deformation amplitude was only 0.31 mm in the XS nail system compared to 0.42 mm in the angular stability plate [41]. Although both implants showed good biomechanical results, the deformation recorded in the XS group proved to be 20% lower than the plate group. The XS nail has the advantages of a simple operation technique, the intraosseous positioning, and saving the pronator quadrates; however, very comminuted fractures are better

To date, no consensus has been reached regarding the optimal treatment of proximal humerus fractures [42]. Instability and fragment displacement usually require surgical treatment for a better quality of life. Highly comminuted fractures

**122**

**Figure 18.**

*(A) Polyaxial stability plate; (B and C) AO/C2 type distal radius fracture, carpal scaphoid fracture; (front and lateral view); (D and E) reduction and osteosynthesis of radius fracture with polyaxial stability plate + additional K wires and osteosynthesis of the carpal scaphoid fracture with Herbert screw + K wire.*

*(A) XS nail in sawbone with aiming device and (B) multidirectional locking of the XS nail with threaded K wires.*

#### **Figure 20.**

*(A) X-ray view of AO/A3 proximal radius fracture and (B) reduction and osteosynthesis with XS nail.*
