Locking Plates-Panacea or Overkill
Journal Title: Journal of Bone and Joint Diseases - Year 2018, Vol 0, Issue 0
Abstract
Orthopaedic fraternity has been taken to storm by locking plates in this decade. It is a welcome trend to seek opinion on social media by posting a x-ray but the dangerous trend is to give instant expert comment” Locking plate”. This has led to the rampant use of these plates leading to reports of unacceptable rate of failures. Implants are blamed for our failure, calling it Implant failure. This is another trend. Faulty technique (e.g. too stiff construct) and uncritical use of locking plates for a broad range of undifferentiated indications (e.g. nonunion) has led to new patterns of failure of fracture fixation in recent years. No doubt, locked plates have introduced a new and exciting dimension to fracture fixation but they should be applied with specific intent and indications; as such their role is continuously being redefined There is no change in concept of fracture healing. Primary healing without callus occurs by compression, preventing micro motion at fracture site, provided by absolute stability while in comminuted type of fractures certain degree of micro motion helps in healing by callus formation, provided by relative stability. While planning management of a fracture, we have to answer a question. Will this fracture unite (1) by compression and needs absolute stability given by conventional compression plates or (2) by relative stability, given by nails or locking plates when used as bridge plate as in cases of comminuted fractures or(3) this needs application of both the principles ,given by combi holes locking plate. Any plate whether conventional or locking, can be used in any or every fracture depending on the mode of its application. We should be aware of the function we want from that plate in that particular situation. Any plate can perform six different functions depending on the mode of its application. 1. Compression mode- When a plate is applied to achieve compression on fracture site as in cases of transverse and short oblique fractures. 2. Neutralization mode- In this type of plating, lag screw is used to achieve compression at fracture site. Here the aim is not to achieve compression by plate .It has already been achieved by lag screw. 3. Buttress mode – is used to give support where fracture may collapse due to unstable fracture pattern as in cases of medial or lateral tibia plateau fractures. 4. Anti-glide mode- Plate is applied in such a way that it prevents slipping of the fragment when the force is applied along the long axis of bone. Fragment is firmly wedged between the plate and main fracture surface. Fixation of post-medial fragment in tibia plateau fractures is a classic example of this type of fixation. 5. Bridging or Span mode- It is used in cases of comminuted fractures where one does not want to dissect the fracture area to avoid de -vitalization of fracture fragments. 6. Tension mode- When plate is solely applied on tension side of fracture and converts tensile force in to compression force. An example of such use is in fracture olecranon Why we need locking plates. Fracture fixation in osteoporosis was a problem. Conventional plate fixation invariably used to get loose. Standard bi- cortical screws were unable to get proper hold .Various methods like augmentation of screws with cement etc. were tried to prevent the loosening ofscrew. Locked plates were developed in response to a need to adequately stabilize fractures in osteoporotic bones. There are definite following advantages of locking plate if used in proper indication. 1. Pre contouring of plate is not required. 2. Periosteal blood supply is preserved as plate does not compress the cortical bone 3. A third advantage to the use of Locking plate screw system is that the screws are unlikely to loosen from the plate. 4. This systems have shown to provide more stable fixation than conventional one. Indications Main indications for the use of a locking plate include four different principals (1)Compression Principle, used in osteoporotic diaphyseal fractures where locking plate with combi holes can be used. Initially compression is achieved by eccentric placement of conventional screws , followed by locking screws (2) Neutralization Principle, also for osteoporotic diaphyseal fractures – where oblique fracture is initially compressed by conventional lag screws and then locking plate is applied as neutralization plate which definitely have better pull out strength (3) Bridging Principle(locked internal fixator) This is a classic and ideal indication for fracture fixation with locking plates (4) In comminuted metaphyseal intra-articular fractures; again by (“combi hole” principle) Contraindications Despite the widespread use of locking plates and their wide range of indications, few contraindications must be acknowledged and respected. A typical contraindication to the use of a locking plate is a simple fracture pattern in healthy bone that requires inter- fragmentary compression. Percutaneous locking plate fixation of simple fractures with use of a minimally invasive technique is another contraindication. This concept violates the principle of the fracture gap width in relation to strain and thus leads to nonunion. Finally, in displaced intra-articular fractures, these injuries require anatomic open reduction and rigid inter-fragmentary compression. Relative contraindication is the cost of implant in a Fracture that can be stabilized satisfactorily with conventional plates, for example, diaphyseal forearm fractures have shown healing rates in excess of 90%with conventional plates. Certain principles of locking plate are still controversial and are in phase of continuous evolution .However common mechanical reasons for failure include inadequate plate length or strength and stiff fracture constructs due to use of too many screws which can lead to nonunion and eventually plate failure. The causes of failure should be examined carefully in both the literature and one’s own practice in order to learn from mistakes and refine our techniques In general; Success begins with a formal pre-operative planning. Precise pre-operative plan reduces the guesswork and increases the likelihood of technical success. There is lot of emphasis on pre- op planning during every symposium held on locking plates. Do we really do? .Let us plan now. Put X-Ray in view box. Decide whether the fracture needs locking plate or conventional plate will be good enough or we need Locking plate with provision of compression (combi holes locking plate). These are the few questions; we have to answer to our selves. What is the fracture zone length .What should be plate length. It should be more than two times of fracture zone length in comminuted fractures. What should be the working length Distance between the proximal and distal screw in closest proximity to the fracture is defined as the “working length” of the plate. Plate working length has been shown to influence construct stiffness, plate strain and cyclic fatigue properties of plate. However controversy still exists regarding the effect of plate working length on stiffness and resistance to fatigue failure. Number and position of screws should be marked on x-rays. Screws should be spread evenly, and ideally there should be at least one empty hole between each pair of holes filled with screws, When the bridging principle is used, even distribution of force over a long working plate length with relatively few screws appears to provide a stable stimulus for indirect bone-healing and callus .For the treatment of peri-articular fractures, few screws are needed in the diaphysis but more screws may be required near the articular surface.. Despite the necessity of mastering these nuances, the use of locking plates will likely to increase, particularly with the increasing prevalence of fragility fractures. But the success of locking plates depends on adherence to established principles of operative fracture care and learning the tricks of the specific technology. Dr. Naresh Chand
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Naresh Chand
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Obituaries
Dr K K Srivastava was born on 26th Sept 1936. He did his MBBS in 1958 from KGMC Lucknow and MS in 1962 from the same institution. He started his lecturership at KGMC in 1962 till 1965. He worked at Willingdon Hospital (n...