No differences in early results of a hybrid glenoid compared with a pegged implant.
BACKGROUND
Glenoid component loosening after total shoulder arthroplasty is one of the most common causes of failure. A hybrid glenoid that uses peripherally cemented pegs and a central press-fit post may improve implant longevity.


OBJECTIVE
We asked, compared with polyethylene pegged glenoid implants, do hybrid glenoid implants with a titanium post provide (1) better ingrowth with fewer radiolucencies, (2) better outcome and pain scores, and (3) lower risk of complications and revisions?


METHODS
Between 2009 and 2010, 126 patients underwent primary total shoulder arthroplasty for osteoarthritis. Patients were included in this retrospective study if they consented for inclusion in a shoulder arthroplasty registry, had complete baseline and 2-year data, and had complete radiographs. Eighty-three (67%) were available at an average followup of 3.2 years (range, 24-45 months). Forty received a conventional all-polyethylene pegged glenoid and 43 received a hybrid component. During the period in question, four of the participating surgeons used only one implant, and four used only the other; there was one high-volume surgeon in each of the study groups. Radiographs were taken at the 2-year followup and analyzed for radiolucent lines. CT scans were obtained randomly for 10 patients with hybrid glenoid implants to assess bone ongrowth. American Shoulder and Elbow Surgeons score, VAS score, complications and revisions were recorded.


RESULTS
At final followup, radiolucent lines between the two study groups were not different (hybrid, 1.0 ± 0.4; pegged, 1.6 ± 0.3; mean difference, 0.6; 95% CI, 0.85-1.72; p = 0.323). Final VAS pain scores were not different (hybrid, 1.2 ± 0.2; pegged, 1.5 ± 0.3; p = 0.056). Change in American Shoulder and Elbow Surgeons scores were not different (hybrid, 33.7 ± 7.3; pegged, 35.5 ± 8.2; p = 0.283). There were no differences in complication risk (hybrid, one of 43 [2.3%]; pegged, three of 40 [7.5%]; relative risk, 2.3; 95% CI, 0.82-3.12; p = 0.061).


CONCLUSIONS
With the numbers available and at early followup, there were no differences between the hybrid and pegged glenoids in terms of fixation, functional outcome, pain scores, and complications. CT scans confirmed bone ongrowth on the porous titanium post in a small subcohort of patients. Further studies are needed to determine how this new implant will perform with time. Until then, its use should be initiated with caution.


METHODS
Level III, therapeutic study.
Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA. GulottaL@hss.edu.
Lawrence V
LV
Gulotta
Coastline Orthopaedics, Fountain Valley, CA, USA.
K Lauchlan
KL
Chambers
Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA.
Russell F
RF
Warren
Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA.
David M
DM
Dines
Hospital for Special Surgery, 535 E 70th Street, New York, NY, 10021, USA.
Edward V
EV
Craig
D000368:Aged; D019643:Arthroplasty, Replacement / Q000009:adverse effects / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012042:Registries; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D014025:Titanium; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D020959:Polyethylene; D014025:Titanium