Faculty Bibliography

Stress fractures of the pubic rami are rare occurrences and most frequently occur in association with total hip arthroplasty (THA). Reported historically with both cemented and noncemented THA components, postoperative stress fractures likely occur secondary to a rapid postoperative increase in patient activity following years of disability. Though stress fractures of the pubic rami should be considered in the differential diagnosis of groin pain following THA, they require a high degree of suspicion. Diagnosis may be achieved via bone scan after ruling out alternative causes of postoperative groin pain and after accounting for associated medical conditions. Treatment is minimally invasive, requiring a limited period of weightbearing and activity modifIcation, often with full resolution of groin pain and a return to postoperative activity levels

The issue of athletic participation after hip and knee arthroplasty has become more relevant in recent years, with an increase in the number of young and active patients receiving joint replacements. This article reviews patient-, surgery-, implant-, and sports-related factors, and discusses currently available guidelines that should be considered by the physician when counseling patients regarding a return to athletic activity after total joint arthroplasty. Current evidence regarding appropriate athletic participation after total hip arthroplasty, resurfacing hip arthroplasty, total knee arthroplasty, and unicondylar knee arthroplasty is reviewed

Reverse total shoulder arthroplasty (rTSA) implants are intended to restore stability and function to shoulders with rotator cuff deficiency. The implant consists of a glenosphere projecting from a glenoid baseplate and articulating in a socket at the proximal end of a humeral component. Despite the demonstrated clinical efficacy, little information is available regarding the joint forces about this construct and the stability of the glenoid component against these forces. Our hypotheses were that the joint forces about the rTSA were comparable to that about a normal shoulder joint, and that the micromotion between the baseplate and the scapula against these loads would be sufficiently low to induce bone ingrowth. To investigate this, a custom testing rig was constructed to simulate active shoulder elevation in fresh-frozen shoulder specimens. The forces about the rTSA were calculated and found to include compressive and shear forces up to 0.7 and 0.4 BW, respectively. In contrast to a normal shoulder, where the joint forces peak at 90 degrees of abduction, forces about the rTSA were highest at about 60 degrees of abduction. These forces were then applied in cyclic loading conditions to the glenoid baseplate, and the micromotion of the implant relative to the bone was measured in the four quadrants of the component. For two different rTSA designs (DePuy Delta III(R) and Encore RSP(R)) and in the entire range of the fixation testing, the cyclical micromotions were always less than 62 microm. Thus, under loading conditions similar to physiological shoulder elevation, micromotion of the glenoid component was sufficiently low and within previously published limits to induce bone ingrowth