SUMMARY 摘要
The principle of the locking compression plate (LCP) is represented by the combination of two completely different anchorage technologies and two opposed principles of osteosynthesis in one implant it combines the principles of conventional plate osteosynthesis for direct anatomical reduction with those of bridging plate osteosynthesis. Since the LCP can be used as a conventional plate using only dynamic compression, as a pure internal fixator using locking head screws,or as both combined, it provides the surgeon with multiple variations. Nevertheless, these new possibilities mean that preoperative planning and an understanding of the different biomechanical principles of osteosynthesis are essential if good clinical outcomes are to be achieved and maximum benefit is to be attained from the options offered by the LCP system. 锁定加压钢板为两种完全不同的固定技术的结合，该内植物包含两种相反的接骨术原理，即以直接解剖复位为特点的传统钢板接骨术和桥接钢板接骨术。LCP既可仅当作动力加压钢板使用，亦可通过锁定螺钉而进作为内支架使用，或是上两种方式的联合，这为外科医师提供多种选择。然而，这些新的可能性亦即意味着，若要想获得LCP系统带来的最大价值及好的临床结果，则必须理解不同的生物力学接骨术原理及做好术前准备。
The current article provides biomechanical background to and guidelines for the use of LC plates in the operative treatment of fractures and also reports experimental and clinical results obtained with LCP。
本文既提供骨折手术治疗时LCP使用的生物力学背景及指南，亦报告应用LCP获得的实验及临床结果。
INTRODUCTION
引言Since the first instance of internal fixation with a plate(carried out by Hansmann in Hamburg in 1886 (8) and the later integration of this principle into operative fracture treatment as a result of Lambotte’s work, both the implants used and the related principles of fracture treatment have been in a state of continuous development.
自第一例应用钢板内固定治疗（1886年，Hansmann在Hamburg实施）及其后 Lambotte将这些整理为骨折手术治疗的原则以来，内植物及骨折治疗的相关原则正持续发展。 While in the early years of internal fixation with plates various principles were pursued in parallel, the standardization of the indications for and techniques of internal fixation with compression plates by the Swiss Association for the Study of Internal Fixation (ASIF) was one of the achievements of the 1950s that were later taken further by the Working Group on Matters Concerned with Internal Fixation (AO). The object of the technique of operative treatment of fractures with compression internal fixation described in the first edition of the AO Manual of Internal Fixation was thus stable internal fixation with the purpose of giving the bone primary strength to allow ;early functional mobilization it was intended that this should be achieved by applying the principle of interfragmentary compression with the object of absolute stability. The dynamic compression plate (DCP) was developed to realize this objective of internal fixation, and it allowed axial compression of the fracture zone by way of eccentric drilling for compression screws. In keeping with this principle, such an internal fixation operation led to primary bone-fracture consolidation without visible callus formation. Conventional plating methods are based on the use of an adequate number of anchoring screws to press the plate against the bone with high compressive forces, creating a stable bone-implant connection. When this technique is used, biocortical screws yield the best possible anchoring force. Even tiny fragments were adapted
in the course of this interfragmentary compression, which required wide exposure of the fracture zone. Denudation of the individual fragments and exposure of the fracture zone consequently led to increased rates of infection, nonunion, and delayed healing, owing to lacking bone and soft tissue vitality.
早年时期钢板内固定遵循着不同的原则，二十世纪五十年代，瑞士内固定协会标化了加压钢板内固定手术技术及手术适应症，随后这些理论由AO进一步发展。第一版AO内固定手册描述骨折加压钢板内固定治疗的目的是坚强内固定，以便术后初期骨骼有足够强度来早期活动，而这可通过骨折块间加压达到骨折端绝对稳定得以实现。动力加压钢板的发展实现了这一内固定目的，它通过偏心钻孔、加压螺钉的放置完成骨折区轴向加压。与这一原则相映，如此内固定手术可导致无可见骨痂形成的一期骨愈合。传统钢板固定方法基于采用足够数量螺钉通过高压应力将钢板固定于骨面而产生稳定骨-内植物连接。应用此技术时，双皮质螺钉固定产生可能的最大把持力。然而，很小的骨折块采用折块间减压技术时，亦要求广泛的骨折区暴露。单个骨折块的剥离及骨折区的暴露因骨、软组织活力的丧失而随之导致感染、骨不连和骨折延迟愈合。
During the 1980s, the principle of absolute stability through interfragmentary compression, which is still valid today in the operative treatment of joint fractures,was increasingly reconsidered against the backdrop of the raised complication rates for osteosynthesis with compression plate systems performed to treat diaphyseal fractures. Not the smallest factor in these considerations was that of the outcomes obtained with medullary nailing, a technique that led to satisfactory treatment results by way of secondary bone healing with callus formation though absolute stability was not achieved. Logically, this led to the concept of internal fixation with bridging plates (1, 7) for the treatment of diaphyseal fractures. According to this principle, the fracture zone of fragmented fractures of a shaft or metaphysis remains undisturbed during surgery following realignment taking account of the axis, length, and rotation, and the bridging plate is anchored in the main fragments proximal and distal to the fracture. In contrast to conventional internal fixation, then, this form of internal fixation yields only relative stability and the secondary bone healing with callus formation is thus no longer an undesirable side-effect, but rather the object of treatment. The nonexposure of the fracture zone means that additional devascularization of bone fragments is avoided. In view of this, the term ?biological plate osteosynthesis― has been introduced for bridging internal fixation (1, 18).
二十世纪八十年代，这一今天仍适用于关节内骨折的治疗原则-骨折块间加压坚强内固定，伴随加压钢板系统治疗骨干骨折后并发症发生率的增高被重新斟酌。髓内钉固定后伴有骨痂形成的二期骨折愈合带来的良好临床结果是促人思考原因之一，因为绝对稳定并无骨痂形成。逻辑上，这引出桥接钢板内固定治疗骨干骨折的原则。根据该原则，骨折手术治疗时，不干扰骨干及干骺端骨折碎块，仅恢复骨折端力线、长度及去旋转，通过桥接钢板技术将远、近主骨块固定。与传统内固定相反，该种内固定方式仅相对稳定，伴有骨痂形成的二期骨愈合不再是临床不想看到的，而是内固定治疗的目的。不暴露骨折区意味着避免格外骨折块失活。有鉴于此，术语生物钢板接骨术因桥接内固定而引入。 Principle and Development of the Locking Compression Plate 锁定加压钢板原理及发展
The revolutionary new aspect of the locking compression plate (LCP) is the combination of two completely different anchorage technologies in one implant.
锁定加压钢板革新之处为一种内植物接合了两种完全不同的内固定技术。
Development of the LCP principle is based on experience gained with the PC-Fix and LISS
systems. In contrast to these systems, the LCP with combination holes gives surgeons the opportunity to combine principles of internal fixation and dynamic compression, depending on the fracture site. The LCP can be used as a compression plate, a locked internal fixator, or a combination of both, depending on the patient’s individual situation (4, 16).
LCP原则的发展基于pc-fix和LISS系统获得的实践。与这些系统相对，拥有联合孔的LCP让术者根据骨折的位置而选择内固定和动力加压。根据患者个体情况，LCP可作加压钢板、锁定内支架或两种结合用。 Application of LCP LCP应用
Relative to conventional plate osteosynthesis, the new generation of LCP requires an adaption to the surgical technique. The importance of the reduction technique and minimally invasive plate insertion and fixation relates to ensuring that bone viability is undisturbed.Understanding of the biomechanical background of bridging plate osteosynthesis is essential if good clinical results are to be obtained. Most of the pitfalls encountered by surgeons using the LCP system have nothing to do with the implants and must be attributed to nonobservation of important basic principles of the concept of biological osteosynthesis (24). These principles are summarized below.
相对传统钢板接骨术，新一代LCP要求适应该手术技术。复位技术及确保骨活力的微创钢板固定技术不得违犯。若想获得良好临床结果，必须理解桥接钢板接骨术生物力学背景。术者应用LCP遭遇的陷阱大部分与内植物无关，此应归因于忽视生物接骨术重要的基本原则。这些原则综述如下。 Length of the LCP LCP的长度
One of the most important steps in the application ofLCP is selection of plates of appropriate length. The lesser soft tissue trauma resulting from the less extensiveexposure of the bone has been seen as a reason for usingshort plates in the past with conventional plating systems, but this no longer applies when LCP are used. Inthis case longer plates can be selected without associated traumatization of the soft tissues, and the lengthselected needs to take account only of the biomechanical situation in the fracture. When the internal fixation is planned the object should be to keep plate loading,which is influenced by both the length of the plate and the placement of the screws, as low as possible. In thecase of LCP the ideal plate length can be determined by the plate span width and the plate screw density (20):the plate span width is the quotient of plate length divided by overall fracture length. This quotient should generally be more than 2-3 for comminuted fractures and higher than 8-10 in the case of simple fractures (6).应用LCP最重要的一步是选好适当长度的钢板。过去，在应用传统钢板时，因钢板越短，要求骨折的剥离越少，软组织创伤就越小而选用短钢板，这一原则不再适用于LCP。此时，因长钢板使用时并无伴随的软组织损伤，钢板长度的选择只需考虑骨折生物力学的需要。实施内固定时，目的是尽可能降低钢板载荷，而钢板载荷受钢板长度荷螺钉位置影响。理想的LCP长度由钢板的跨越宽度及螺钉的密度决定：钢板跨越宽度为钢板长度与骨折总长度相除之商。对于粉碎性骨折而言商数应为2-3倍，对简单骨折则为8-10倍。 Number and Positioning of Screws 螺钉数目和位置
A second value is of equal importance: screw density (quotient of screws inserted divided by number ofplate holes). Experience has shown that this value shouldbe under 0.4-0.5. In contrast to conventional plateosteosynthesis, when LCP are used it is no longer possible to recommend a
definite number of screws or cortices to be used in each fragment. Anchorage in the main fragments proximal and distal to the fracture zone remains important nevertheless, it is much more important that the number of screws inserted is as small as is consistent with the provision of high plate leverage so that screw loading is kept low. Two monocortical screws should be the minimum for each main fragment, to keep the construct stable. For safety reasons, we generally recommend two to three screws per main fragment, so that stability will be ensured even if insertion of one of the screws is less than optimal. The use of biocortical screws in each fragment does not improve the situation from the aspect of screw failure, but does improve that of the interface between screw and bone, and it is therefore recommended that at least one of the screws in the main fragment (6) should be a biocortical screw. Axial pullout of the screws is determined by the outer diameter of the screw. An increase from 4.5mm (conventional cortical screw) to 5.0mm (Locking Head screw) provides already 70% holding force in a monocortical Locking Head screw (LHS) compared to a 100% of the holding force of a conventional bicortical 4.5mm screw.
同样重要的第二数值为螺钉密度（即为植入螺钉数目除以钢板螺孔数之商）。经验显示该值应小于0.4-0.5。与传统钢板接骨术相比，应用LCP时不再推荐每块骨折块固定的确切的螺钉数或皮质数。骨折远、近端主骨块的固定仍然重要，但更重要的是尽可能少的植入螺钉数与高钢板力矩一致，以使螺钉载荷更小。为保持内固定结构体稳定，至少应用两枚单皮质螺钉固定主骨块。从安全角度考虑，即使多置入一枚螺钉并非更佳，但为确保稳定，我们一般推荐每主骨块固定两至三枚螺钉。双皮质螺钉的应用并未改善螺钉失败，但其增加螺钉-骨结合，因此建议每主骨块至少使用一枚双皮质螺钉。螺钉的轴向拔出力由螺钉外径决定。外径从4.5mm（传统螺钉）增至5.0mm（锁定螺钉），使得单皮质使用的锁定螺钉提供传统双皮质固定的普通螺钉的70%把持力。
The positions of the screw holes actually used relative to the fracture are also very important when LCP are used. Dynamic loading tests have shown that in the case of fractures where there is no bone contact between the main fragments (comminuted fractures), when screws are not inserted in the holes at each side of the fracture, with an effective increase in the length of bone bridged, this leads to premature failure of the implant. In these biomechanical tests, plate failure was regularly found to occur at the DCP screw hole on which finite element analysis revealed the most intense Misse stresses (27). Such stress is reduced by increasing the bridging length, since the forces are distributed over a larger area of the plate. In the case of simple fractures with bone contact when fracture spaces are small this is not a problem. On the other hand, additional screws increase the stress on the implant, as greater loads are required to achieve bone contact (27). On the basis of these results, it can be recommended that in the case of simple fractures where there is bone contact one or two combination holes be left unused on each side of the fracture space, while in the case of complex fractures with an extensive fragmented zone and resultant lack of bone contact the holes closest to the fracture should be used. A small interval between plate and bone also causes attenuation of the leverage exerted on the bone-implant complex, while a sufficiently long plate increases the axial rigidity, as mentioned above (6). However, an aiming device should be used in every case during drilling for the locking head screws, since axial deviation of thedirection of drilling by more than 5° leads to significantly impaired stability (10).
应用LCP时，相对骨折处而言螺孔位置也非常重要。动态载荷测试显示，当骨折处无骨接触（粉碎性骨折）时，若螺钉未置在骨折两边的螺孔，随桥接骨长度的增加，内植物将更早失败。在这些生物力学测试中，使用有限元对DCP分析发现，Misse应力最大的钢板螺孔处常常失败。该应力可通过增加桥接长度减小，因载荷分布于钢板更长区域。当骨折间隙小
时，有折块端接触的简单骨折不是问题。另一方面，增加螺钉将提高内植物应力，因此时要使骨折端接触需更大载荷。基于这些结果，建议有骨折断面接触的简单骨折可不固定骨折两端螺孔，而骨折范围大、无断面接触的粉碎骨折则需固定。内植物-骨界面小间隙消弱结构体杠杆作用，但如上所述，足够长的钢板提高内植物装置轴向刚度。然而，植入锁定螺钉钻孔时应使用瞄准装置，因为钻孔方向轴向偏移大于5o可导致稳定性明显受损。
The principles detailed above apply to bridgingosteosynthesis to be performed for correction of diaphyseal and metaphyseal fractures. In the case of metaepiphyseal fractures this principle can be deviated frominsofar as the combination holes in the area of the joint allow anatomical realignment and internal fixation in keeping with the principle of interfragmentary compression, while at the same time the metaphyseal region can be well served by a bridging osteosynthesis. The number of screws in the area of the joint depends solely on the object of refixation with interfragmentary compression. This combination of two different principles of internal fixation in a single implant is one of the main advantages of the LCP. In cases where both – conventional screw and locking head screws are applied – it is necessary to apply the LHS after the conventional screw.If the conventional screw would be applied after the LHS, the screw – bone interface would be overloaded and the screw would be worthless. 上述祥则适用于骨干及干骺端骨折的桥接固定。应用于干骺端骨折时，与骨折块间加压原则一致，可通过联合孔对关节内骨折块实施解剖复位固定，而同时，在干骺端则可施行桥接钢板技术。关节区域螺钉数仅依赖于骨折块间加压再固定目的。两种不同内固定原理在同一钢板结合是LCP主要优点之一。当普通螺钉和锁定螺钉同时应用是，应先使用普通螺钉。若普通螺钉后使用，螺钉-骨界面载荷将过大、螺钉亦无效。 Shaping of the LCP LCP塑形
In conventional plate osteosynthesis, stability is provided by adapting the implant to the bone. The screwsare used to apply a compressive preload at the interfacebetween plate and bone. This means that accurate shaping of the plate is essential. When the LCP is used as an internal fixator, exact adaptation of the implant to the bone surface is not necessary. Nevertheless, even in the case of diaphyseal fractures it can be beneficial to bend the plate between the screw holes in such a way as to ensure that the different screws face in different directions, increasing resistance to detachment in keeping with the principle of polyaxial anchorage. This is of most benefit in bone affected by osteoporosis. It is also beneficial to bend the LCP in the area of the metaphysis,though in this case no more than a rough adaptation is necessary, to prevent an extreme amount of space between the plate and the bone. This ensures less stress on the soft tissue and also leads to diverging directions of the screws, affording increased resistance of the osteosynthesis to detachment.
普通钢板内固定时，稳定性由内植物施加于骨而提供。此时螺钉在钢板-骨界面产生加压预载荷。这意味着钢板需精确塑形。当LCP用作内支架时，内植物无需与骨面精确匹配。然而，甚至在骨干骨折时，遵照多轴固定原则，为保证不同螺钉位于不同方向以提高内植物抵抗分离阻力，在两螺孔间折弯钢板是有益的。这在骨质疏松性骨折时最为重要。同样，在干骺端时，LCP无需精确塑形，但适当折弯仍为有益。因为这保证软组织更小应力，也致使螺钉改变方向而提供更大阻力对抗结构体分离。 Anatomically Preshaped LCP 解剖型LCP
Since it is not necessary for the plates to be tailored precisely to the bone for each patient, in the further course of the LCP’s development preshaped plates were devised for use in fractures in
锁定加压钢板原理及临床应用
