Cath Lab Digest

Locking compression plates have a number of advantages over conventional plate fixation and may provide ideal fixation for fusions of the first metatarsophalangeal joint. Accordingly, these authors examine the merits of these devices and offer salient surgical pearls.

   Arthrodesis of the first metatarsophalangeal joint (MPJ) is a well-documented, reliable and reproducible procedure for many pathologies of the first MPJ. Advances in fixation technique have led to even better results over the past 10 to 15 years and the recent advent of locking compression plates (LCPs) has made an outstanding procedure even better.

   For every article on implant arthroplasty that shows good results, there are 20 articles on first MPJ arthrodesis that show good or excellent results. Implant arthroplasty has limited use for the first MPJ and the literature supports this undeniably. For those who perform first MPJ arthrodesis on a regular basis, we will offer a closer look at a superior fixation technique, which allows patients to ambulate postoperatively. For those who do more implant arthroplasty, hopefully we will influence you to take a second look at arthrodesis.

   Conventional plate fixation has greatly evolved since its introduction for fracture stabilization and anatomical reduction. The original method involved the concept of complete fracture stability in order to promote primary bone healing, which requires rigidity and little to no bony callus formation.

   Conventional plating also requires direct contact between the plate and the bone, which can result in a loss of periosteal blood supply from too much compression. This phenomenon is referred to as “early temporary porosity” or “stress shielding,” which causes the bone beneath a plate to become porous and weak.¹ These bony defects could eventually cause re-fracturing or nonunions.²

Pertinent Pointers On The Unique Design Of Locking Plates

   Locking plates, in contrast to conventional plating, allow for some motion between fracture fragments or a fusion site. This motion promotes secondary bone healing and subsequent callus formation.

   A locking plate is often referred to as an internal fixator or a fixed-angle construct. It acts as a “simple beam,” which moves as one construct. The locking plate resists screw pullout and toggle, especially in osteoporotic or comminuted bone.³ The fixed angle construct is able to convert axial loads into compressive forces instead of shear frictional forces like one would see with the conventional plate.^3,4

   Locked plating also stabilizes a fracture without the need of plate contouring, which again helps maintain blood supply to the bone.² Wagner, et al., discuss initial clinical data for the use of locking plates for internal fixation of fractures. They note “excellent union rates, low rates of fixation failure and few associated complications.”²

   Locking compression plates combine conventional plating with locked plating techniques and the use of locking head screws for the ultimate fixed-angle construct.^1,4,5 A threaded interface between the screw heads and the body of the plate allows for angular and axial stability. This design also prevents compression of the plate into the bone, preserving osseous blood supply. When it comes to osteoporotic bone, instead of needing the screw to engage into the bone, one securely tightens the screw into the plate itself. This reduces the chance of loosening or further damage to the already weakened bone.