Radiographic assessment of ingrowth total shoulder arthroplasty

Sixty-two primary ingrowth total shoulder arthroplasties, performed between 1989 and 1992 and with a minimum radiographic and clinical follow-up of 2 years or until the time of revision surgery (mean, 4.6 years), were reviewed. To combine data on both the distribution and the thickness of periprosthetic lucency and change in component position, criteria were used to determine whether a component was radiographically "at risk" for clinical component loosening. A glenoid component was "at risk" when a complete lucent line was present, some part of it being 1.5 mm or greater in width, or when 2 of 3 or 3 of 3 independent observers identified migration or tilt of the component. A humeral component was "at risk" when a lucent line 2 mm or greater in width was present in 3 or more of 8 zones or when at least 2 of 3 independent observers identified tilt or subsidence of the component. Four (6.5%) of the 62 glenoid components and 6 (9.7%) of the 62 humeral components were judged to be "at risk." There were no identifiable patient, disease, or surgical characteristics associated with the development of an "at risk" glenoid or humeral component. Currently, despite this very favorable radiographic assessment, we reserve the use of a tissue ingrowth glenoid component for those patients with bone loss precluding bone cement fixation with a keel type of implant. Because advantages exist for use of a tissue ingrowth humeral component, a press-fitted component with ingrowth surfaces is currently used unless bone deficiencies prevent secure fixation without cement.