These authors conducted a retrospective review of 171 total shoulder arthroplasty (TSA) patients with minimum 2-year clinical followup to determine whether resorption was associated with inferior outcomes or higher rates of radiographic loosening. The inclusion criteria identified consented patients treated with the same primary third-generation TSA system (Turon; DJO) with complete preoperative data and minimum 2-year follow-up clinical and radiographic data. The senior author performed all TSA procedures. A press-fit technique was used for humeral stem insertion in all cases. Humeral stem size was based on the first sequential broach that obtained rotational stability, typically achieving metaphyseal fixation rather than diaphyseal fixation. Morsalized bone graft from the humeral head was placed into the prepared humeral canal shortly before impaction of the final stem. The glenoid was prepared using standard noncannulated reamers, creating a concentrically matched surface for the glenoid component, often partially correcting glenoid version. The glenoid component was cemented in all cases, with pressurization of cement into the prepared glenoid surface and placement of cement behind the component prior to impaction.
Calcar resorption was identified in 110 patients (64.3%).
No significant overall differences were observed between the patients with and without calcar resorption.
Subgroup analysis showed that patients with grade 3 resorption had a higher incidence of glenoid radiolucencies (50%, P ..001) and patients with a progression from grade 1 to grade 3 had higher incidences of glenoid (50%) and humeral (9%) radiolucencies.
Comment: It is surely of note that almost two thirds of these patients had medical calcar osteolysis. The authors point out pathologic processes may lead to bone resorption of the medial calcar, ranging from more benign conditions such as stress shielding and remodeling to more concerning processes such as debris induced osteolysis from glenoid and third-body wear or an evolving infection. The association of glenoid loosening shown in the tables and in figure 2 (above) may indeed be due to polyethlene wear. The possibility of infection can only be examined by taking cultures at the time of a revision surgery, which was not a part of this study.
In the figure below, one can see a case of the association of calcar absorption and glenoid component failure in a case where the three month films showed some superior displacement of the humeral component relative to the glenoid.
No significant overall differences were observed between the patients with and without calcar resorption.
Subgroup analysis showed that patients with grade 3 resorption had a higher incidence of glenoid radiolucencies (50%, P ..001) and patients with a progression from grade 1 to grade 3 had higher incidences of glenoid (50%) and humeral (9%) radiolucencies.
Comment: It is surely of note that almost two thirds of these patients had medical calcar osteolysis. The authors point out pathologic processes may lead to bone resorption of the medial calcar, ranging from more benign conditions such as stress shielding and remodeling to more concerning processes such as debris induced osteolysis from glenoid and third-body wear or an evolving infection. The association of glenoid loosening shown in the tables and in figure 2 (above) may indeed be due to polyethlene wear. The possibility of infection can only be examined by taking cultures at the time of a revision surgery, which was not a part of this study.
Patients seen to have calcar bone resorption deserve close followup to detect early evidence of prosthetic loosening.
In our practice we avoid placement of cement behind the component prior to impaction out of concern that this thin layer of cement will fragment as the component is loaded.
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