The current status of locked plating: the good, the bad, and the ugly

Locked plate technology has evolved in an effort to overcome the limitations associated with conventional plating methods, primarily for improving fixation in osteopenic bone. The development of screw torque and plate-bone interface friction is unnecessary with locked plate designs, significantly decreasing the amount of soft tissue dissection required for implantation, preserving the periosteal blood supply, and facilitating the use of minimally invasive percutaneous bridging fixation techniques. The locked plate is a fixed-angle device because angular motion does not occur at the plate screw interface. The use of locked plate technology allows the orthopaedic surgeon to manage fractures with indirect reduction techniques while providing stable fracture fixation. The secure 'feel' of locked plates, ease of application, and the low incidence of complications noted in early clinical reports have contributed to the proliferation of this technology. Along with reports of clinical successes, as the use of fixed angle/locked plates has increased, clinical failures are being noticed. This review will focus on the biomechanics of locked plate technology, appropriate indications for its use, laboratory and clinical comparisons to conventional plating techniques, and potential mechanisms of locked plate failure that have been observed.     

Additional fixation of medial plate over the unstable lateral locked plating of distal femur fractures: A biomechanical study

IntroductionLateral locked plating is a standard treatment option for distal femur fractures. However, the unstable conditions after lateral locked plating are increasing. The objective of this study was to investigate the biomechanical strength of additional medial plate fixation over the unstable lateral locked plating of distal femur fractures.Materials and methodsA distal femur fracture model (AO/OTA 33-A3) was created with osteotomies in the composite femur. Three study groups consisting of 6 specimens each were created for single-side lateral locked plating with 6 distal locking screws (LP-6), single-side lateral locked plating with 4 distal locking screws (LP-4), and additional medial locked plating on LP-4 construct (DP-4). A compressive axial load (10 mm/min) was applied in the failure test. Mode of failure, load to failure, and ultimate displacement were documented.ResultsAll single-side lateral locked plating (LP-4 and LP-6) showed plate bending at the fracture gap, while none of the DP-4 showed plate bending at the fracture gap. Load to failure of DP-4 (mean 5522 N) was 17.1% greater than that of LP-6 (mean 4713.3 N, p < 0.05) and 29.2% greater than that of LP-4 (mean 4273.2 N, p < 0.05). Ultimate displacement of DP-4 (mean 5.6 mm) was significantly lower than that of LP-6 (mean 8.8 mm, p < 0.05) and LP-4 (mean 9.1 mm, p < 0.05).ConclusionsAdditional fixation of medial plate significantly increased the fracture stability in distal femur fractures fixed with the lateral locked plating. Especially in the clinical situations where sufficient stability cannot be provided at the distal segment, the medial plate may be considered as a useful biomechanical solution to obtain adequate stability for fracture healing.     

Biomechanical Stability of Four Fixation Constructs for Distal Radius Fractures

Implants available for distal radius fracture fixation include dorsal nonlocked plating (DNLP), volar locked plating (VLP), radial–ulnar dual-column locked plating (DCPs), and locked intramedullary fixation (IMN). This study examines the biomechanical properties of these four different fixation constructs. In 28 fresh-frozen radii, a wedge osteotomy was performed, creating an unstable fracture model and the four fixation constructs employed (DNLP, VLP, DCPs, and IMN). Dorsal bending loads were applied and bending stiffness, load to yield 5 mm displacement, and ultimate failure were measured. Bending stiffness for VLP (16.7 N/mm) was significantly higher than for DNLP (6.8 N/mm), while IMN (12.6 N/mm) and DCPs (11.8 N/mm) were similar. Ultimate load to failure occurred at 278.2 N for the VLP, 245.7 N for the IMN, and 52.0 N for the DNLP. The VLP was significantly stronger than the DNLP and DCPs, and the IMN and DCPs were stronger than the DNLP. The VLP has higher average bending stiffness, ultimate bending strength, and resistance to 5 mm displacement than the other constructs and significantly higher ultimate bending strength than the DCPs and DNLP. There was no statistically significant difference between the VLP and IMN. VLP and IMN fixation of distal radius fractures can achieve comparable stability.     

Volar approach to distal radius fractures

The volar approach to the distal radius fracture is an important exposure in the treatment of these fractures, particularly with the growing enthusiasm for fixed-angle volar plating. With reports in the literature documenting complications associated with external fixation and dorsal plating, the volar approach has become ever more popular. Moreover, advancements in locking plate technology have expanded the indications for palmar plating beyond volar shear and volarly displaced fractures to include unstable intra-articular distal radius fractures. The surgical approach remains the same as when Henry recommended the interval between the flexor carpi radialis and the radial artery. Critical elements of the surgical technique include releasing the brachioradialis, gaining exposure all the way to the sigmoid notch, and building the intra-articular reduction, beginning with the intermediate column and moving radially. The relevant anatomy, indications and contraindications, postoperative care, and a pertinent case presentation are discussed.     

Results in treatment of distal femur fractures using polyaxial locking plate

Indications and techniques of locked plate fixation for the treatment of challenging fractures continue to evolve. As design variant of classic locked plates, the polyaxial locked plate has the ability to alter the screw angle and thereby, enhance fracture fixation. The aim of this observational study was to evaluate clinical and radiographic results in 89 patients with 90 fractures of the distal femur treated, between June 2006 and November 2011, with such a polyaxial locked plating system (Polyax™ Locked Plating System, DePuy, Warsaw, IN, USA). Seventy-seven fractures formed the report of this study. These cases were followed up until complete fracture healing or for a mean time of 77 weeks. At the time of last follow-up, 58 of 77 fractures (75.3 %) progressed to union without complication and radiographic healing occurred at a mean time of 16.3 weeks. Complications occurred in ten fractures that did not affect the healing and in nine fractures that showed delayed or non-union. The mean American Knee Society Score at the time of final follow-up was 83 for the Knee Score and 71.1 for the Functional Score. In conclusion, there is a high union rate for complex distal femoral fractures associated with a good clinical outcome in this series.     

Fixation of diaphyseal fractures with a segmental defect: a biomechanical comparison of locked and conventional plating techniques

BACKGROUND: Locking plates are an alternative to conventional compression plate fixation for diaphyseal fractures. The objective of this study was to compare the stability of various plating with locked screw constructs to conventional nonlocked screws for fixation of a comminuted diaphyseal fracture model using a uniform, synthetic ulna. Locked screw construct variables were the use of unicortical or bicortical screws, and increasing bone to plate distance. METHODS: This biomechanical study compared various construct groups after cyclic axial loading and three-point bending. Results were analyzed via one-way analysis of variance. Displacements after cyclical axial loading and number of cycles to failure in cyclic bending were used to assess construct stability. RESULTS: The constructs fixed by plates with bicortical locked screws withstood significantly more cycles to failure than the other constructs (p < 0.001). Significantly less displacement occurred after axial loading with bicortical locked screws than with bicortical nonlocked screws. Increased distance of the plate from the bone surface, and use of unicortical locked screws led to early failure with cyclic loading for constructs with locked screws. CONCLUSIONS: These results support the use of plating with bicortical locked screws as an alternative to conventional plating for comminuted diaphyseal fractures in osteoporotic bone. Bicortical locked screws with minimal displacement from the bone surface provide the most stable construct in the tested synthetic comminuted diaphyseal fracture model. The results of this study suggest use of plates with unicortical screws for the described fracture is not recommended.     

When a volar locking plate is not the right choice in fractures of the distal radius: Case based technical considerations

A volar approach is commonly used for fixation of distal radius fractures with a volar locking plate. There are certain fracture patterns for which volar locked plating is not suitable. This case based review outlines such case examples.     

Locked plating in orthopaedic trauma: a clinical update

Locked plating for fracture fixation has enjoyed widespread popularity despite a paucity of published data on outcomes. Anatomically precontoured locked plates that allow fixation in various anatomic regions are widely available. New technologies incorporate subchondral support locking pegs, polyaxial bushings, and locking washers to improve intraoperative versatility. However, limited data are available on the efficacy of these new implants. The clinical performance of locked plates generally has been good. However, several unique complications have been noted, such as difficulty with implant removal, malalignment, fracture distraction, and loss of diaphyseal fixation, especially with percutaneous techniques and unicortical screws. The expense of locked plate constructs is a concern. This technology typically costs three times more than similar unlocked constructs. Locked constructs should be reserved for problematic fractures that have demonstrated poor outcomes with unlocked constructs.     

Current concepts in locked plating

Approaches to internal fixation have become more biologic. Greater emphasis is placed on vascularity and soft tissue integrity. Locked plates, analogous to rigid internal fixators, can provide relative stability favorable to secondary fracture healing. If applied appropriately, they can avoid soft tissue compromise. The key to this new generation of plates is the locking mechanism of the screw to the plate, which provides angular stability and avoids compression of the plate to the periosteum. Favorable biomechanical and clinical results continue to expand the number of appropriate indications for use of locked plating devices, although exact indications for their use have yet to be precisely defined.     

Flexible fixation and fracture healing: do locked plating 'internal fixators' resemble external fixators?

External and internal fixators use bone screws that are locked to a plate or bar to prevent periosteal compression and associated impairment of blood supply. Both osteosynthesis techniques rely on secondary bone healing with callus formation with the exception of compression plating of simple, noncomminuted fractures. External fixation uses external bars for stabilization, whereas internal fixation is realized by subcutaneous placement of locking plates. Both of these "biologic" osteosynthesis methods allow a minimally invasive approach and do not compromise fracture hematoma and periosteal blood supply. Despite these similarities, differences between the two fixation methods prevail. Locked plating "internal fixators" allow a combination of biomechanical principles such as buttressing and dynamic compression. Periarticular locking plates are anatomically contoured to facilitate fixation of articular fractures. They allow for subchondral stabilization using small-diameter angular stable screws as well as buttressing of the joint and the metaphyseal component of a fracture. Biomechanically, they can be far stiffer than external fixators, because subcutaneous plates are located much closer to the bone surface than external fixator bars. External fixators have the advantage of being less expensive, highly flexible, and technically less demanding. They remain an integral part of orthopaedic surgery for emergent stabilization, for pediatric fractures, for definitive osteosynthesis in certain indications such as distal radius fractures, and for callus distraction.     

Effects of near cortical slotted holes in locking plate constructs

The development of locked plating has led to substantial improvements in fracture fixation. This is particularly evident in periarticular fractures, in which conventional nonlocking plates are unable to support the articular surface from a single side. Initially, locked plating appeared to be the ideal solution for these situations and reduced the necessity for double plating and secondary bone grafting. However, with increasing use of locked plating, it became evident that the plate-bone interaction is rigid and may lead to impaired bone healing. The near cortical locking holes increased the construct stiffness and appeared to interfere with local healing. Slotted near cortical locking holes might improve this drawback. This review summarizes the current knowledge of the healing process associated with different types of near cortical locking options.     

Operative treatment of femoral shaft fractures in children and adolescents

Although femoral shaft fractures constitute fewer than 2% of all fractures in children and adolescents, their treatment has produced many pieces of literature and years of controversy. Prevailing opinion has favored nonoperative and operative treatment, and a variety of techniques have been advocated to avoid complications such as nonunion, limb-length discrepancy, malalignment, osteonecrosis, and growth disturbance. Currently, operative methods of treatment generally are favored to allow early ambulation and shorter hospital stays and to avoid detrimental psychological and social effects often associated with prolonged nonoperative treatment, and to avoid complications. Options for operative fixation include external fixators, flexible and locked intramedullary nails, and compression and bridge plating. Although all of these can obtain good results in particular situations, there is no clear consensus of the indications for each. My choice for fixation of each fracture is based on consideration of a number of factors, including the age and size of the child, associated injuries, the location and pattern of the fracture, and the social situation of the child. In general, I prefer flexible nailing for younger children (6-10 years old) and locked nailing for adolescents at or near skeletal maturity. Bridge plating may be chosen for segmental, grossly comminuted fractures, whereas external fixation usually is reserved for severely comminuted or severe open fractures for which internal fixation is not appropriate.     

Repair of mandibular fractures: plating vs. traditional techniques.

The treatment of mandibular fractures is a challenge for the otorhinolaryngologist-head and neck surgeon. Recent technologic advances have resulted in the development of rigid fixation techniques that hold promise for the early and optimal restoration of mandibular structure and function. The purpose of this article is to review the dental and orthopedic principles used in our mandibular fracture management, describe compression plating methodology, and discuss optimal techniques for its use. Results using rigid fixation procedures were compared with those using a variety of more traditional techniques in a retrospective analysis of 57 cases. The advantages, limitations, and indications for use of plating technology are discussed, and prevention of complications is emphasized.     

MIPPO技术下LCP锁定固定减少锁钉个数后应力遮挡效应的有限元研究

目的比较经锁定固定减少锁钉个数后骨痂应力均值的变化,研究LCP锁定固定减少锁钉个数对应力遮挡效应的影响,为MIPPO术中应用不同类型的接骨板和固定方式提供生物力学依据。方法应用有限元法根据LCP的锁定与加压结合孔,建立胫骨上端骨折LCP锁定固定后带骨痂的三维有限元模型。对模型进行力学有限元分析,得出不同工况和内固定方式下骨痂应力情况。结果骨痂在锁定固定减少2个锁钉条件下的应力均值大于减少1个锁钉条件下的应力均值,根据配对t检验结果两者差异具有统计意义。锁定固定减少2个锁钉导致的应力遮挡率小于减少1个锁钉条件下的应力遮挡率。结论 MIPPO技术下LCP锁定固定均采用锁定钉固定时应该减少不必要的锁钉,使在提供稳定固定的同时减少应力遮挡效应,促进骨痂的生成和骨痂改建塑形,有助于骨折愈合。     

Metaphyseal locking plate as an external fixator for open tibial fracture: Clinical outcomes and biomechanical assessment

ObjectiveThis study aimed to evaluate the outcome of using a metaphyseal locking plate as a definitive external fixator for treating open tibial fractures based on biomechanical experiments and analysis of clinical results.MethodsA metaphyseal locking plate was used as an external fixator in 54 open tibial fractures in 52 patients. The mean follow-up was 38 months (range, 20–52 months). Moreover, static axial compression and torsional tests were performed to evaluate the strength of the fixation techniques.ResultsThe average fracture healing time was 34.5 weeks (range, 12–78 weeks). At 4 weeks postoperatively and at the final follow-up, the average Hospital for Special Surgery knee score was 85 (range, 81–100) and 94 (range, 88–100), respectively, and the American Orthopaedic Foot and Ankle Society score was 88 (range, 80–100) and 96 (range, 90–100), respectively. Based on the static test result, the axial stiffness was significantly different among groups (p = 0.002), whereas the torsional stiffness showed no significant difference (p = 0.068).ConclusionsClinical outcomes show that the use of locking plate as a definitive external fixator is an alternative choice for tibial fractures after obtaining appropriate fracture reduction. However, external locked plating constructs were not as strong as standard locked plating constructs. Therefore, the use of external locked plating constructs as a definitive treatment warrants further biomechanical study for construct strength improvement.     

Fracture pattern and fixation type related to loss of reduction in bicondylar tibial plateau fractures

IntroductionBicondylar tibial plateau fractures can be treated with locked plating applied from the lateral side with or without additional application of a medial plate (dual plating). Recent studies demonstrate that these injuries can be sub-grouped based upon their morphology by computed tomography (CT). The purpose of this study is to evaluate the relationship between fracture pattern, method of fixation and loss of reduction in bicondylar tibial plateau fractures.Patients and methodsPreoperative CT scans and postoperative plain films were evaluated on a consecutive series of bicondylar tibial plateau fractures. Fracture patterns were classified by CT. Angular alignment was measured immediately postoperatively and again at clinical and radiographic union to assess loss of reduction.ResultsA total of 140 patients were studied. Sixty-six (47%) had a single large medial fragment with the articular surface intact, 19 (14%) had a medial articular fracture line with a mainly sagittal component and 55 (39%) had a coronal fracture through the medial articular surface. A total of 129 patients had been treated with lateral locked plating alone whilst 11 patients (all with a coronal fracture of the medial condyle) underwent dual plating.There was little loss of reduction (median subsidence 0.5°) when lateral locked plating was employed alone in patients with a single medial fracture fragment or with a sagittal medial fracture line. When lateral locked plating was used in the presence of a medial coronal fracture line, there was a significantly higher rate of subsidence (median 2.0°) compared to those with no medial fracture line (p = 0.002). Patients with coronal fracture lines treated with dual plating had significantly less loss of reduction that those treated with lateral locked plating (p = 0.01).ConclusionsMost patients with bicondylar tibial plateau fractures do well when treated with lateral locked plating. However, those with a medial coronal fracture line tend to have a higher rate of subsidence and loss of reduction when lateral locked plating is employed alone. These fractures may be better treated with dual plating if the soft tissues allow.Level of evidenceLevel III (retrospective comparative study).     

锁定钢板结合植骨治疗SanderⅢ、Ⅳ型跟骨骨折

目的探讨切开复位锁定钢板内固定结合植骨治疗SanderⅢ、Ⅳ型跟骨骨折的疗效。方法对32例跟骨骨折患者（36足）采用切开复位锁定钢板内固定并髂骨植骨治疗。结果术后切口均无感染。32例均获随访,时间6—18（10．4±3．3）个月。未发现关节面塌陷、复位丢失、螺钉固定不良现象。功能及疗效按照Maryland足部评分系统评价：优22例,良6例,可3例,差1例,优良率为87．5％。结论锁定钢板内固定结合髂骨植骨治疗SanderⅢ、Ⅳ型跟骨骨折是一种有效的方法,充分的术前准备、熟悉跟骨的解剖形态、术中精准的复位、内固定的技巧、时机的掌握是手术成功的关键。     

General principles for the clinical use of the LCP

The basic principles of an internal fixation procedure using a conventional plate and screw system (compression method) are direct, anatomical reduction and stable internal fixation of the fracture. Wide exposure of the bone is usually necessary to gain access to and provide good visibility of the fracture zone to allow reduction and plate fixation to be performed. This procedure requires pre-contouring of the plate to match the anatomy of the bone. The screws are tightened to fix the plate onto the bone, which then compresses the plate onto the bone. The actual stability results from the friction between the plate and the bone. Anatomical reduction of the fracture was the goal of conventional plating technique, but over time a technique for bridging plate osteosynthesis has been developed for multifragmentary shaft fractures that, thanks to a reduction of vascular damage to the bone, permits healing with callus formation, as seen after locked nailing. Since the damage to the soft tissues and the blood supply is less extensive, more rapid fracture healing can be achieved. The newly developed, so-called locked internal fixators (e.g.PC-Fix and Less Invasive Stabilization System (LISS)), consist of plate and screw systems where the screws are locked in the plate. This locking minimizes the compressive forces exerted by the plate on the bone. This method of screw-plate fixation means that the plate does not need to touch the bone at all, which is of particular advantage in so-called Minimal Invasive Percutaneous Osteosynthesis (MIPO). Precise anatomical contouring of a plate is no longer necessary thanks to these new screws and because the plate does not need to be pressed on to the bone to achieve stability. This prevents primary dislocation of the fracture caused by inexact contouring of a plate. The LISS plates are precontoured to match the average anatomical form of the relevant site and, therefore, do not have to be further adapted intraoperatively. The development of the locked internal fixator method has been based on scientific insights into bone biology especially with reference to its blood supply. The basic locked internal fixation technique aims at flexible elastic fixation to initiate spontaneous healing, including its induction of callus formation. This technology supports what is currently known as MIPO. The development of the Locking Compression Plate (LCP) has only been possible based on the experience gained with the PC-Fix and LISS. With reference to the mechanical, biomechanical and clinical results, the new AO LCP with combination holes can be used, depending on the fracture situation, as a compression plate, a locked internal fixator, or as an internal fixation system combining both techniques. The LCP with combination holes can also be used, depending on the fracture situation, in either a conventional technique (compression principle), bridging technique (internal fixator principle), or a combination technique (compression and bridging principles). A combination of both screw types offers the possibility to achieve a synergy of both internal fixation, methods. If the LCP is applied as a compression plate, the operative technique is much the same as conventional technique, in which existing instruments and screws can be used. The internal fixator method can be applied through an open but less invasive or an MIPO approach. An indirect closed reduction is necessary when using the LCP in the internal fixator method bridging the fracture zone. A combination of both plating techniques is possible and valuable, depending on the indication. It is important to command a knowledge of both techniques and their different features.     

Innovations in locking plate technology

Plating techniques remain the mainstay for managing most periarticular and selected long bone fractures. However, movement toward more biologically appropriate plating techniques is occurring in an attempt to minimize soft-tissue stripping, decrease the need for bone grafting, and improve union rates. Internal fixation with locking plates creates a toggle-free, fixed-angle construct. Early data on the biomechanical and clinical performance of these implants are encouraging. Current indications for locked plating include periarticular fractures, typically those with metaphyseal comminution. Although impressive union rates have been reported, malunion remains a concern, especially when percutaneous techniques are used. Further clinical and biomechanical research on locking plate technology is needed to define its place fully alongside existing technology in orthopaedic trauma.     

Early healing with locked condylar plating of periprosthetic fractures around the knee

Management of periprosthetic fractures around the knee is often difficult because of poor bone quality, comminution, and constraints imposed by the existing prosthesis. Locked condylar plates may provide more reliable fixation for these fractures than traditional methods of fixation. Eleven patients with periprosthetic fractures around the knee were treated with open reduction and internal fixation using a locked condylar plate. All 9 acute fractures and 1 of 2 periprosthetic nonunions healed at an average of 21 weeks, and no patient required additional surgery. Nine fractures healed in anatomical alignment, whereas 1 healed in 5 degrees valgus. The remaining periprosthetic nonunion developed a persistent nonunion with subsequent hardware failure. The average range of motion was 4 degrees to 92 degrees . Locked plating systems are highly effective for the management of complex periprosthetic fractures around the knee. They result in reliable fracture healing and permit early motion in complex fractures.