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The purpose of this study was to evaluate the relative contribution of the reverse shoulder arthroplasty (RSA) humeral stem length on initial implant fixation, which may contribute to the long-term success of uncemented shoulder implants. Three RSA humeral components were randomly divided into the following testing groups: (1) 100% Stem length (n = 7); (2) 50% Stem length (n = 7); (3) 0% Stem length (n = 7). Each humeral stem was press-fit into twenty-one 4th Generation Osteoporotic Sawbones humeri. Torque and compressive axial load were applied to the humerus for 10,000 cycles at ±2.5 Nm and −392 N, respectively. Rotational micromotion of the implant was measured. Micromotion for all 3 testing groups was below the 150 µm micromotion threshold throughout testing. The overall micromotion in Group 2 was significantly larger than Group 1 (P <.001) and Group 3 (P <.001). Overall micromotion between Group 1 and Group 3 were not significantly different (P =.686). All stem lengths studied maintained micromotion below the 150 µm threshold, suggesting that any of these treatment groups would provide adequate initial fixation to allow bony on-growth. Clinically, stemless or short-stemmed prosthesis design offer theoretical benefits such as the degree of freedom for humeral stem placement independent of diaphysis. This study concluded that the zero-length stem will allow for this and provide adequate fixation comparable to the full-length stem. Basic Science Study. [ABSTRACT FROM AUTHOR]

Revision total shoulder arthroplasty is performed for a variety of patient symptoms, including shoulder pain, instability, or stiffness. The technical reasons found for revision include component loosening or malposition. Removing the humeral stem during revision can increase morbidity and blood loss during a procedure. The ability to use a universal stem that can be utilized in both anatomic and reverse shoulder arthroplasty can be beneficial in three main areas. For revision surgeries, cost is much less, OR time is decreased, and complications are much less frequent. [ABSTRACT FROM AUTHOR]

Cemented humeral stem fixation in shoulder joint arthroplasty has been, and continues to be the “gold standard” to ensure satisfactory implant orientation and stability. The most commonly performed type of shoulder arthroplasty is hemi-arthroplasty in the face of comminuted fracture. Appropriate stem height and version relative to the glenoid is paramount in obtaining a satisfactory result. This has been proven to be reliably reproducible through cement fixation of the stem with careful reattachment of the tuberosities. Total shoulder arthroplasty in rheumatoid patients with questionable bone stock likewise has relied upon “cementation” of the humeral component to ensure secure fixation, prevent loosening and avoid subsidence. In younger patients it is tempting to want to avoid cement in the proximal humerus, nonetheless most studies have demonstrated loosening of the humeral component not to be problematic once cement has been used. In addition, newer modular componentry allows head removal (without stem removal) providing ready access to the glenoid should glenoid revision be needed. The ability to add antibiotics within the cement mantle in high-risk patients additionally affords an advantage in treating and/or avoiding infection. Survivorship studies have not demonstrated any advantage of cementless versus cement fixation of the humeral component in shoulder arthroplasty. Temporizing techniques such as cup arthroplasty and hybrid techniques such as placing tantalum weave surfaces proximally for enhanced tuberosity fixation may have a role, but do not replace the long-standing efficacy of cement fixation of the humeral component in the vast majority of patients requiring shoulder arthroplasty. [ABSTRACT FROM AUTHOR]

There is an increasing shift toward the use of uncemented stems in total shoulder arthroplasty (TSA) and a rapidly growing collection of stem designs and geometries. However, there are limited data in the literature analyzing the performance or the optimal fixation technique of these various designs. Twenty-nine patients underwent TSA with a press-fit humeral stem using cancellous fixation. Radiostereometric analysis was used to detect stem loosening postoperatively. At 2-year follow-up, radiolucencies were detected in 4 of 26 stems with no clinical evidence of component loosening. Cancellous fixation of the humeral stem appears adequate for a stable bone–prosthesis interface in TSA. [ABSTRACT FROM AUTHOR]