UW Shoulder and Elbow Academy: Trabecular metal glenoid components

Cemented versus Uncemented Fixation of Second Generation Trabecular Metal Glenoid

In 2003, the first generation Trabecular MetalTM (Zimmer, Warsaw, IN, USA) metal backed polyethylene glenoid component was introduced. The first generation Trabecular MetalTM-backed glenoid components exhibited a high failure rate due to fracture at the component keel/tantalum disc interface and was taken off the market in 2005. The second-generation TM glenoid was introduced in 2009.

Apparently surgeons implant this glenoid component using either cement or using a press-fit without cement. Cementation is performed with cement applied on the component’s back side, covering only the peripheral polyethylene surface.

This study compared outcomes for two surgeons, one of whom routinely cemented the glenoid component and utilized a lesser tuberosity; the second surgeon routinely implanted the glenoid component without cement and utilized a subscapularis peel.

Minimum 5 year followup was available for 55 shoulders; 27 in the cemented group (21 with full radiographic follow-up) and 28 in the uncemented group (22 with full radiographic follow-up).

No patients required revision surgery.

Groups had similar preoperative ROM, but uncemented patients had greater follow-up forward flexion (p=0.03), external rotation (p<0.01) and lateral elevation (p=0.03) when compared to cemented patients.

ASES scores (89.8 cemented vs. 94.1 uncemented, p=0.21) were also similar.

The uncemented group demonstrated significantly higher rates of radiolucent lines and higher frequency of mild metal debris. Mid-term radiographs showed a metal debris rate of 24% in the cemented group and 27% in the uncemented group.

No implants required revision.

Below are the radiographs showing a shoulder with a cemented TM glenoid at 5.7 year followup. There is intra-articular metal debris, radiolucency, and superior translation of the humeral head on the glenoid component.

Comment: While the significance of metal debris has not been rigorously defined, it may indicate migration of the component as reflected in the table above.

It is noted that the insertion of this component requires removal of a substantial amount of bone, which may complicate revision (see prior post at this link).

In total shoulder arthroplasty, cement on the backside of the component is unnecessary if the bone is properly prepared and the glenoid component properly seated.

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