This systematic review compares the biomechanical principles of conventional plates versus locked plating systems. It covers plate-screw function (neutralization, buttress, bridge), fracture gap strain physiology, and the distinct mechanical behavior of conventional plates, PC-Fix, LCP, and LISS constructs. The central question: when does each system work, and why does one fail where the other succeeds?
The AO group built compression plating on one mechanical assumption: enough screw torque to generate enough friction to hold the plate to bone. That assumption collapses in osteoporotic or severely comminuted bone, where the available torque (≤3 Nm) is insufficient to keep the construct stable at physiological loads.
When you encounter osteoporotic bone, comminuted diaphyseal or metaphyseal fractures, or anatomy that prevents tension-side plating, reach for a locked plate. The locking mechanism bypasses friction entirely, summing fixation across all screws and converting the construct's failure mode from screw pullout to plate bending — a far more robust failure point.
For periarticular fractures demanding anatomic reduction and primary healing (think both-bone forearm, simple articular splits), conventional compression plating remains the right tool. Primary healing requires gap strain below 2%, which locked plates are not optimized to achieve.
One rule to carry into every case with a combination-hole LCP: compression first, locked screws last. Reversing that sequence creates a mechanically incoherent hybrid that achieves neither absolute nor relative stability.
This systematic review compares the biomechanical principles of conventional plates versus locked plating systems. It covers plate-screw function (neutralization, buttress, bridge), fracture gap strain physiology, and the distinct mechanical behavior of conventional plates, PC-Fix, LCP, and LISS constructs. The central question: when does each system work, and why does one fail where the other succeeds?
The AO group built compression plating on one mechanical assumption: enough screw torque to generate enough friction to hold the plate to bone. That assumption collapses in osteoporotic or severely comminuted bone, where the available torque (≤3 Nm) is insufficient to keep the construct stable at physiological loads.
When you encounter osteoporotic bone, comminuted diaphyseal or metaphyseal fractures, or anatomy that prevents tension-side plating, reach for a locked plate. The locking mechanism bypasses friction entirely, summing fixation across all screws and converting the construct's failure mode from screw pullout to plate bending — a far more robust failure point.
For periarticular fractures demanding anatomic reduction and primary healing (think both-bone forearm, simple articular splits), conventional compression plating remains the right tool. Primary healing requires gap strain below 2%, which locked plates are not optimized to achieve.
One rule to carry into every case with a combination-hole LCP: compression first, locked screws last. Reversing that sequence creates a mechanically incoherent hybrid that achieves neither absolute nor relative stability.