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Background: Acetabular fractures are uncommon in children and adolescents, mainly because of predominant cartilaginous component and strong surrounding ligaments. Although acetabular fractures at this age can lead to significant disability, there is no consensus regarding management, which continues to be controversial. Particularly, long-term outcome after operative management has not been evaluated., Case Presentation: We report a case of a 13-year-old boy skeletally immature who presented with an isolated acetabular fracture involving the posterior wall secondary to a traumatic hip dislocation. A Kocher-Langenbeck approach with a surgical luxation of the hip was used for reduction and mini-plate internal fixation of the fracture. Long-term (17-year) follow-up showed a good clinical outcome and a good congruence of the. The patient has bilateral beginning osteoarthritis due to a cam configuration of both hips CONCLUSION: We describe a case of successful operative management of an acetabulum fracture in a skelettaly immature child with a long-term follow-up. Aggressive management of this rare type of fractures may lead to durable positive outcome.

The purpose of the present study was to biomechanically compare the primary stability of our formerly described inside-out plate fixation to the classic double screw fixation for scarf osteotomy in the treatment of hallux valgus. We performed 20 scarf osteotomies on first metatarsal composite bone models. One half were fixed using a double screw technique and the other half using a locking plate inside-out technique. Using a testing device to simulate the physiologic load, the specimen was loaded until failure, and the load at failure, displacement at failure, and work at failure were recorded. The results were compared between the 2 groups and against the findings from intact sawbones. Compared with the intact bone models, the energy absorption was low for both types of osteotomy fixation. Between the 2 fixation groups, the load at failure was greater for plate fixation, although the difference was not statistically significant (p = .051). However, a statistically significant difference was found between both groups comparing work and displacement at failure (p < .001). In conclusion, the formerly described inside-out plating technique is a biomechanically reasonable alternative to screw fixation because of its primary stability after scarf osteotomy for hallux valgus., (Copyright © 2018 The American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Intramedullary nailing still remains the golden standard for the treatment of diaphyseal fractures of the long bones in adults. The operative technique is standardised and usually minimal invasive, the primary healing rate is high, and complications arise rarely. However, for problem zones (meta-diaphyseal region), in poor bone quality and in other relative contraindications for nailing (narrow medullary canal, fractures in adolescents and polytrauma) the new angular stable screw-plate-systems (LISS, LCP) offer an excellent alternative for the operative stabilisation. The high primary stability in combination with newly developed minimal-invasive techniques (MIPO = minimal invasive plate osteosynthesis) are the bases for a functional after treatment and a rapid bony consolidation with a low complication rate.

The Locking Compression Plate (LCP) is a new screw-plate system that offers the possibility of inserting conventional and locking head screws into the specially designed combination holes. It represents a further development of the PC-Fix and the LISS and was released for clinical application in March 2000. In a prospective multicentre study, the new system was used to treat 144 patients (f: 67, m: 77; average age: 51.4 years) with 169 fractures: of these, 57 were tibial fractures, 45 humerus, 19 radius and 18 femoral. After one year, clinical and radiological follow-up assessment was carried out on 127 patients with 151 fractures (88%). In 130 fractures (86%), healing took place within the expected period and without complication or secondary dislocation ("uneventful healing"). In 19 patients, a total of 27 unexpected complications occurred ("adverse events"), in which 18 revision operations were necessary in 13 patients: five for implant loosening/pull-out, four for plate failure, one for non-union, five for secondary fractures immediately adjacent to the implant after a subsequent injury and two for infection. Analysis by a committee of experts indicated that mechanical complications arose entirely from technical errors of application (incorrect fixation technique, incorrect choice of plate). No purely implant-related complications were observed. The new system can be regarded as technically mature. It offers numerous fixation possibilities and has proven its worth in complex fractures situations and in revision operations after the failure of other implants. A good knowledge of biomechanics is essential as well as precise preoperative planning.

The Locking Compression Plate (LCP), in combination with the LISS and the PHILOS, is part of a new plate generation requiring an adapted surgical technique and new thinking about commonly used concepts of internal fixation using plates. The following guidelines are needed to avoid failures and possible complications in the hands of surgeons not yet confident with the new implant philosophy. The importance of the reduction technique and minimal-invasive plate insertion and fixation is addressed to keep bone viability undisturbed. Understanding of mechanical background for choosing the proper implant length and the type and number of screws is essential to obtain a sound fixation with a high plate span ratio and a low plate screw density. A high plate span ration decreases the load onto the plate. A high working length of the plate in turn reduces the screw loading, thus fewer screws need to be inserted and the plate screw density can be kept low. Knowledge of the working length of the screw is helpful for the proper choice of monocortical or bicortical screws. Selection is done according to the quality of the bone structure and is important to avoid problems at the screw thread bone interface with potential pullout of screws and secondary displacement. Conclusive rules are given at the end of this chapter.

The Medoff sliding plate was designed to treat unstable intertrochanteric and subtrochanteric fractures. This plate has a dual sliding capability along both the femoral shaft and neck in order to improve bone coaptation, interfragment compression and hence load-sharing between bone and implant in hip fractures. In a retrospective study of 63 patients (mean age 82 (51-98) years) with intertrochanteric (n 44) and high subtrochanteric fractures (n 19), we assessed the results with the Medoff sliding plate. All patients, except 1 lost to follow-up, were examined clinically and radiographically. 14 patients died within 1 year, and in the other, the mean follow-up was 15 (6-30) months. 1 technical failure occurred, leading to a single reoperation. The low technical failure rate suggests that the Medoff sliding plate with combined compression modus is suitable for treating intertrochanteric and high subtrochanteric fractures.

Mechanical unloading of the plated bone segment is observed after plate osteosynthesis because the implant takes over a part of the physiological loading. Strain reduction in the bony tissue depends on the rigidity of the plate (cross-sectional area, geometrical form, and modulus of elasticity). The aim of the present study was to calculate theoretically the effect of plate position relative to bending direction on the overall bending stiffness of the composite system plate-bone. To calculate the rigidity, a cylindrical bone model with mechanical characteristics similar to a sheep tibia and a rectangular plate cross-section corresponding to a DC-plate with either a modulus of elasticity of steel or titanium was used. Calculations under different bending directions were performed according to the laws of the linear bending theory and the composite beam theory. The bending stiffness of a plate osteosynthesis reaches a minimum and a maximum respectively, in cases in which the bending moment acts in the direction of the main axis of the area moment of inertia of the plate. The minimum is present with the plate bent vertically, the maximum with the plate bent horizontally, e.g. on the tension side of the composite system--on the assumption that the bone structure opposite the plate is capable of withstanding compressive loading. For steel and titanium plates, factors of 2 and 2.25 respectively were calculated between the minimum and the maximum bending stiffnesses of the osteosynthesis. The bending rigidity of the plate alone has only a minimal effect on the total stiffness of the osteosynthesis. With a plate bent vertically, the difference between steel and titanium plates was 18%, with the plate bent horizontally (situated on the tension side), it was only 7%. The bending stiffness of a plate osteosynthesis depends on the cross-section, the geometrical form, and the modulus of elasticity of the plate, as well as on the plate position relative to the bending direction of the composite system. The modulus of elasticity of the plate is relatively unimportant, while with a given plate the individual plate position relative to the bending direction is of crucial importance. Thus, changing the modulus of elasticity of the plate cannot solve the problem of implant induced unloading of the bone cortex because the bending stiffness of the composite system depends much more on the plate position relative to the bending direction.

After plate osteosynthesis changes in bone biology and bone mechanics are observed in the plated bone segment. Compromise of the vascular supply in the plate bed leads to a remodelling process and to a temporary porosity in the bone cortex underneath the plate. In addition, the plate takes over some of the physiological loading of the bone, which in turn alters the normal strain distribution of the cortical bone tissue. The aim of the present study is to determine the tissue deformation of the sheep tibia in vivo and the changes in tissue strain due to plating with plates of different rigidities. Measurements were performed on the intact bone at the mid diaphysis using the strain gauge technique. With different connections on the tension bridge (Wheatstone bridge), the strain was measured separately for pure axial loading, bending, and torsion before and after plating with a 4.5 mm stainless steel or titanium DCP. Under physiological load the sheep tibia is mainly deformed in torsion (62%) and bending (33%), and much less in axial loading (5%). Plating with a steel plate reduces the overall tissue strain by 18%, with a titanium plate by 13%. This reduction is mainly due to a reduction in axial tissue strain due to axial loading and bending and less to the reduction of tissue strain under torsion. In our in vivo model, plating with steel or titanium plates leads to a reduction of the physiological tissue strains. The difference between the different plates is small due to the fact that the high tissue strain under torsion is only slightly affected by plating. Thus, from the purely mechanical point of view and with regard to preserving normal tissue strains as much as possible, titanium plates offer little advantage compared with stainless steel plates. But, titanium as an implant material may offer advantages with respect to tissue compatibility and infection resistance.

There has been an evolution in the AO/Association for the Study of Internal Fixation plating technique during the past 3 decades that includes the use of longer plates and fewer plate screws, fewer lag screws outside the plate, fewer unicortical screws at the plate periphery, and greater use of the 95 degrees blade plate to achieve balanced fixation of proximal and distal shaft fractures. These changes reflect an evolving technique of plate osteosynthesis that emphasizes indirect reduction techniques, biologic internal fixation, and improved biomechanics. Outcome data suggest that there has been an improvement with time that is reflected by shorter time to union, a decrease in the frequency of implant failures, delayed unions, nonunions, malunions, number of reoperations, and in overall rate of failure. The best predictor of success was the length of plate by logistic regression analysis. With the evolution of plating techniques and a greater emphasis on biology of fracture healing, the incidence of complications and failures has decreased after femoral shaft plating. Plate osteosynthesis of the femoral shaft is particularly advantageous in many situations and can be quite successful (87% success rate in Group III).

A new technique to achieve a reliable fusion of the hip joint through an anterior approach with use of a ventral low contact dynamic compression plate and a lateral 6.5 mm lag screw is presented in detail. The advantages of this technique are that the approach does not jeopardize the vascularity of the femoral head, that the fixation on the pelvic side uses the strong bone stock of the sciatic buttress, and that the hip abductor muscles and greater trochanter are preserved. The authors also present the indications and the results of their experience with 12 patients. The followup period averaged 24.8 months (range, 10-42 months). Ten patients (83%) achieved a solid fusion by radiologic and clinical criteria. Although a moderately symptomatic nonunion developed in 1 patient, another patient went on to a painful nonunion to whom another attempt for fusion has been recommended. According to the hip score of Merle d'Aubigné and Postel, the average figures for pain and ambulation increased from 3.2 points to 5.0 points and from 2.7 points to 4.5 points, respectively, after surgery. Six of the 12 patients regained the ability to work in their former jobs or in new occupations. Eight patients felt no or minor restrictions in doing their former sports activities. Patient satisfaction was high with a majority reporting minor discomfort mainly around the fused hip.

The continually evolving understanding of bone biology and the analysis of clinical complications have led to a modified approach in internal fixation using plates. Anatomical reduction of the fragments in comminuted diaphyseal and metaphyseal fractures itself is no longer a goal. Important reduction aims are the correct length of the bone, and axial and torsional alignment. The preservation of the viability of the bone fragments is the key to unimpaired fracture healing. The primary stability of an osteosynthesis seems to be of minor importance for bone healing. More important is the rapid integration of unreduced but vital fragments into the fracture callus which buttresses the fracture area opposite the plate reducing the risk for overload and fatigue failure of the implant. Additional primary bone grafting leeds to local vascular disturbance of the bone and is rarely indicated. Indirect reduction technique with the aid of the fracture table or the distractor and a minimal but optimal use of implant material is the new concept to achieve undisturbed fracture repair in metaphyseal and diaphyseal fractures. In articular fractures the anatomic restoration of the articular surface can be obtained by the combination of indirect reduction technique (ligamentotaxis, soft tissue taxis) and accurate direct reduction of certain strategic fragments. Modifications of the plate design (limited contact, point contact) which minimize additional vascular damage to the bone help to accomplish this new concept.

Our continuously evolving understanding of bone biology has led to a new approach to plate fixation. In comminuted fractures, anatomical reduction of all fragments is no longer a goal in itself. Preservation of the viability of the bone fragments seems to be the key to unimpaired fracture healing in internal fixation. The rapid integration of unreduced but vital fragments into the fracture callus functions as a bio-buttress system and prevents fatigue fracture of the implant. To realize the new concept of biological internal fixation, the limited contact dynamic compression plate, which minimizes vascular damage to the plated bone segment, has been developed.

To realize the new concept of biological internal fixation the limited contact dynamic compression plate was developed. It minimizes vascular damage to the plated bone segment. It should lead to a more versatile and efficient application of internal fixation using plates.