Abstract
Introduction:
Studies have demonstrated both clinical and radiological success of reverse shoulder arthroplasty (RTSA), with follow-up approaching 10-years. To date, most RTSA studies involve cemented fixation of the humeral components, and most involving uncemented RTSAs have used implants not necessarily designed for bony ingrowth. Cementless fixation utilizing proximally porous-coated (PPC) femoral implants has shown long term survivorship approaching 99% at greater than 10-years follow-up in total hip arthroplasty. Currently, the number of commercially available PPC RTSA implants is steadily growing, but there has been no published study examining clinical and radiographic outcomes in PPC, press-fit humeral stems. We hypothesized that the clinical and radiographic results of uncemented RTSA utilizing a PPC humeral stem would be similar to cemented RTSA stems when followed for at least 2-years.
Methods:
A prospective, IRB approved RTSA outcomes registry with 261 patients that underwent RTSA by one fellowship-trained orthopaedic surgeon between 2005 and 2008 was reviewed. Inclusion criteria were diagnosis of cuff tear arthropathy or severe rotator cuff deficiency refractory to all other treatments, and minimum 2-year clinical and radiographic follow-up. Exclusion criteria were proximal humeral fractures, glenohumeral instability, rheumatoid arthritis, incomplete follow-up, and revision arthroplasty. Outcome measures included active forward elevation (aFE), active external rotation (aER), active internal rotation (aIR), Constant-Murley score (CS), Subjective Shoulder Value (SSV), visual analogue scale (VAS) pain, and American Shoulder and Elbow Surgeons (ASES) score. Radiographs at 2 weeks, 3 months, 1 year, 2 years and yearly thereafter were evaluated for humeral component position, osteolysis, humeral component radiolucent lines (RLLs), stress shielding, and scapular notching. Statistical analysis was conducted by an independent institutional statistician.
Results:
The cemented (n = 37) and uncemented (n = 64) cohorts demonstrated comparable age and gender. Average follow-up was 32.4 months in the uncemented group (range 23–52) and 37.0 months in the cemented group (range 23–70). Both cohorts demonstrated significant improvements from preoperative to most recent follow-up in CS, ASES score, SSV, VAS pain, aFE, and aIR (P < 0.05). The cemented cohort showed a significant improvement in aER (P < 0.01), but the uncemented cohort did not (P = 0.14). There was no significant difference when comparing the degree of improvement in any of these values between the cemented and uncemented cohorts (P > 0.05). Radiographically, there was no evidence of humeral component loosening, osteolysis, or component failure observed in either cohort at any time point. There was no significant difference (P = 1.0) in the incidence of humeral component RLLs between the cemented (n = 1) and uncemented (n = 2) cohorts. Stress shielding was observed in 5 uncemented shoulders and 0 cemented shoulders, however this was not significantly different (P = 0.15). There was no significant difference (P = 0.30) in the incidence of scapular notching between the cemented (n = 8) and uncemented (n = 10) cohorts.
Conclusion:
Cementless fixation of a porous-coated RTSA humeral stem provides equivalent clinical and radiographic outcomes compared to cemented stems at minimum 2-year follow-up. With advantages such as decreased operative time, no risk of cement-related complications, and ease of revision, cementless fixation may provide several benefits over cemented fixation. Longer-term studies are needed comparing outcomes of cemented versus cementless RTSA.
