Boundary lubrication A monolayer of lubricant molecule (lubricin) adsorbed on each surface (boundary) of the joint prevents direct cartilage to cartilage (articular) contact Fluid-film lubrication Cartilage surfaces are separated by a fluid film 1. Hydrodynamic lubrication: 2. Squeeze film lubrication: 2. Elastohydrodynamic lubrication: Combination of hydrodynamic and squeeze film Mixed…
Tag: Biomechanics
Surgical Skills 
Biomechanics in MIPO (Minimally Invasive Plate Osteosynthesis)
1. Provides optimal environment for fracture healing: 2. Relative stability of fracture: 3. Acts as internal fixator: 4. Plate length and Number of screws in Bridge plate function: 5. Plate working length: References:
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Z-effect and Reverse Z-effect in PFN
‘Z-effect’ and ‘Reverse Z-effect’ are complications relating to differential migration of screws that arise from fixation of unstable proximal femoral fractures with Proximal Femoral Nail (PFN) having 2 interlocking head screws. The 4 patterns of unstable intertrochanteric fracture hip are: Z-effect: The Z-effect involves the lateral migration of the lag…
Surgical Skills 
Orthopedic Screw Insertion Mnemonic
Don’t Marry Too Soon DRILL Choose the correct drill bit Insert the drill bit correctly in the chuck Tighten the chuck sufficiently Start the drill home perpendicular to the surface Maintain adequate pressure Maintain the proper direction Irrigation with normal saline should be commenced simultaneously with drilling Keep the drill…