Radiographic stability of ingrowth humeral stems in total shoulder arthroplasty.

BACKGROUND

Cemented and uncemented stem types are available for TSA. An early uncemented stem designed for bone ingrowth had radiographic loosening of approximately 10% at intermediate followup (mean 4.6 years). Subsequent stem modifications included circumferential metaphyseal porous coating to enhance ingrowth and reduce loosening rates.

QUESTIONS/PURPOSES: We asked whether the radiographic loosening rates would be lower after this design modification and whether the pain score and ROM would be improved.

PATIENTS AND METHODS

We reviewed the medical records and radiographs of 76 patients undergoing primary TSA with circumferential metaphyseal porous-coated stems for osteoarthritis between 1995 and 2005. All patients had a complete standardized series of radiographs preoperatively, postoperatively, and at final followup. Humeral stems were evaluated for any radiolucent lines by zone, progression of lucencies, and shift in component position. The minimum radiographic followup was 25 months (average, 52 months; range, 25-90 months).

RESULTS

There were no radiolucencies seen on the initial postoperative radiographs. Five stems had 1-mm radiolucent lines in one to four of eight zones at final followup. One had a glenoid component judged at risk. None of the humeral components were judged at risk or loose or to have shifted. The pain scores and ROM improved postoperatively.

CONCLUSIONS

Proximally coated humeral stems for TSA showed few radiolucencies and no loosening at short- to midterm followup, reflecting an improvement over previous series. We now use these stems for primary TSAs and reserve cemented stems only when uncemented fixation is not possible owing to bony deficiency.

LEVEL OF EVIDENCE

Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.