A variety of precontoured plates are available for most bones in the body. When compared with traditional, manually contoured implants, these can be advantageous because they typically have clusters of screw holes in the periarticular region, allowing for multiple points of fixation in the short- end segments. They are also convenient and can save time that would otherwise be required to contour an implant, especially when a stout plate or complex multiplanar contour is required. Finally, although percutaneous and less invasive fracture surgery techniques are not implant specific, many precontoured plates have associated insertion handles and aiming jigs that can be helpful adjuncts to less invasive techniques.
However, precontoured plates do have disadvantages and limitations. In some cases, the surgeon may choose to use the implant to facilitate a reduction by affixing it to 1 fragment and drawing the other fragment to the plate. This can be done by contouring the implant by hand to fit the injured bone or with a precontoured plate. However, this reduction strategy is very sensitive to implant placement. For example, in the distal femur, placing the plate posteriorly on the distal segment can result in medialization and external rotation of the segment (ie, the "golf club" deformity). Importantly, the surgeon must also recognize that implant geometry is determined by the manufacturer to approximate typical anatomy and is not specific to any particular patient. Recent work in the proximal humerus and distal femur has demonstrated that often, the precontoured plate does not fit the patient's anatomy in the coronal plane despite an ideal plate position, usually beause of undercontouring.[45,46] In these situations, using the implant indiscriminately as a reduction template (eg, using nonlocking screws or the threaded reduction tool to pull the diaphysis to the plate) can produce deformity. In the proximal humerus, this can result in lateralization of the diaphysis and a varus malreduction. In the distal femur, it can also result in medialization of the distal segment and loss of normal limb alignment (Figure 7). Alternative strategies to prevent this include the manual contouring of the precontoured implants or the use of locking screws, which facilitates stable fixation despite a lack of plate-to-bone contact.
Radiographs demonstrating postoperative AP of two different patients with distal femur fractures treated with lateral precontoured implants. A, In this patient with a periprosthetic distal femur fracture, the diaphysis was brought into contact with the plate. Because the implant was undercontoured, lateralization of the diaphysis relative to the distal segment occurred. B, In the second patient, the more proximal, simple fracture line was clamped and fixed with an independent lag screw. To restore length, alignment, and rotation of the metaphysis, an external fixator was used for provisional fixation, and locking screws were used in the diaphysis to maintain this relationship, leaving a gap between the undercontoured region of the plate and the lateral femur. If the diaphysis had been brought into contact with the plate, a deformity similar to Figure 6A would likely have occurred.
J Am Acad Orthop Surg. 2020;28(14):585-595. © 2020 American Academy of Orthopaedic Surgeons