Two studies find similar long-term survivorship of cemented all-polyethylene and metal-backed glenoid components

In analyzing 20 or more years of total shoulder arthroplasty results, Mayo Clinic investigators studying the fate of glenoid components recently identified male gender as a risk factor for revision and said lucencies around cemented metal-backed implants are concerning.

The first study, led by Tyler J. Fox, MD, and published in the Journal of Shoulder and Elbow Surgery, found a direct relationship between the type of glenoid component and component revision rates.

In the second study, which appeared in the Journal of Bone and Joint Surgery, Mayo Clinic researchers found an 83% lucency rate with cemented metal-backed glenoid implants at minimum radiographic follow-up of 2 years.

“The high rate of glenoid periprosthetic lucency is concerning and requires additional follow-up and investigation,” the study’s first author, Nattapol Tammachote, MD, and colleagues wrote in their abstract. “These results are not better than those that have been reported for all-polyethylene cemented glenoid components."

Component differences

Fox’s study included six styles of glenoid components implanted in 1,542 shoulders of 1,337 patients operated on between Jan. 1, 1984 and Dec. 31, 2004. Investigators determined survivorship by implant type at 5, 10 and 15 postoperative years or less with newer designs.

They found the type of implant was significantly associated with revision (P < .001). A metal-backed ingrowth design fared the worst with 86% survivorship at 5 years, 79% survivorship at 10 years and 67% survivorship at 15 years follow-up.

By comparison, survivorship of some cemented all-polyethylene designs reached 99% at 5 years and 94% at 15 years postoperatively. Men had a higher risk for glenoid revisions. Investigators also reported there was an increased risk of revision for post-traumatic arthritis and avascular necrosis compared to degenerative arthritis.

“Survival is improved with cemented, all-polyethylene glenoid components,” Fox and colleagues wrote in their abstract.

Treatment for osteoarthritis

Tammachote’s study involved 100 cemented metal-backed glenoid components implanted during total shoulder arthroplasties (TSAs) performed for shoulder osteoarthritis between 1985 and 1991. The researchers followed 95 of the cases for 2 years minimum through revision (mean, 10.8 years).

Results using the modified Neer rating system were excellent in 47 shoulders. Pain relief and motion improved following implantation of cemented metal-backed glenoids for osteoarthritis, investigators noted.

In commenting on the findings, Winston J. Warme, MD, of the University of Washington Medical Center in Seattle, told Orthopedics Today, “The topic of glenoid component survival is timely and relevant as glenoid loosening remains a common failure mechanism in patients undergoing TSA.”

Another study Warme cited reported a glenoid component loosening rate of 63% with failed TSA.

“Of particular concern is the finding that glenoid periprosthetic lucency was present in 69 (83%) of 83 shoulders at a minimum radiographic follow-up of 2 years,” he said.

In another report by Martin et al, there was a seven times higher annual risk of revision with metal-backed among patients with radiographic signs of failure, Warme added.

“The finding that male patients and those with post-traumatic arthritis and avascular necrosis were at increased risk for failure is well established and is the putative rationale for the interest in alternative glenoid techniques in the younger, more active patient,” he said.

References:
Fox TJ, Cil A, Sperling JW et al. Survival of the glenoid component in shoulder arthroplasty. J Shoulder Elbow Surg. 2009; Mar 16 [Epub ahead of print].
Martin SD, Zurakowski D, Thornhill TS. Uncemented glenoid component in total shoulder arthroplasty. J Bone Joint Surg Am. 2005;87:1284-1292.
Tammachote N, Sperling JW, Vathana T, et al. Long-term results of cemented metal-backed glenoid components for osteoarthritis of the shoulder. J Bone Joint Surg Am. 2009;91:160-166.