The impact of scapular notching on reverse shoulder glenoid fixation

J Shoulder Elbow Surg. 2013 Jul;22(7):963-70. doi: 10.1016/j.jse.2012.10.035. Epub 2013 Jan 16.


Background: Scapular notching is a well-documented complication of reverse shoulder arthroplasty. The effect of scapular notching on glenoid fixation is unknown.

Materials and methods: This study dynamically evaluated reverse shoulder glenoid baseplate fixation and assessed the effect of scapular notching on fixation in composite scapulae. A cyclic test was conducted to simulate 55° of humeral abduction in the scapular plane as a 750-N axial load was continuously applied to induce a variable shear and compressive load. Before and after cyclic loading, a displacement test was conducted to measure glenoid baseplate displacement in the directions of the applied static shear and compressive loads.

Results: For the scapulae without a scapular notch, glenoid baseplate displacement did not exceed the generally accepted 150-μm threshold for osseous integration before or after cyclic loading in any component tested. For the scapulae with a scapular notch, glenoid baseplate displacement exceeded 150 μm in 2 of the 7 samples before cyclic loading and in 3 of the 7 samples after cyclic loading. The average pre-cyclic glenoid baseplate displacement in the direction of the shear load was significantly greater in scapulae with a scapular notch than those without a scapular notch both before (P = .003) and after (P = .023) cyclic loading.

Conclusions: Adequate glenoid baseplate fixation was achievable in most cases in scapulae with a severe scapular notch; however, the fact that this micromotion threshold was not met in all scapulae with a notch is concerning and implies that severe notching may play a role in initial glenoid baseplate stability.

MeSH terms

  • Arthroplasty, Replacement / adverse effects
  • Arthroplasty, Replacement / methods
  • Biomechanical Phenomena
  • Compressive Strength
  • Humans
  • Joint Instability / etiology
  • Joint Instability / prevention & control
  • Joint Prosthesis*
  • Models, Anatomic
  • Models, Educational
  • Prosthesis Design / methods*
  • Prosthesis Failure*
  • Range of Motion, Articular / physiology
  • Scapula / physiopathology*
  • Scapula / surgery
  • Shoulder Joint / surgery*
  • Stress, Mechanical