Clinical Experience With the Zimmer Trabecular Metal (TM) Glenoid in Total Shoulder Arthroplasty

Total shoulder arthroplasty is successful in relieving pain and restoring function to the joint, but chronic loosening of the glenoid implant remains a common complication. The Zimmer Trabecular Metal (TM) Glenoid is a monoblock implant for reconstructive total shoulder arthroplasty. To date, no published clinical data is available to confirm evidence on the effectiveness of this specific product.

The purpose of this prospective study is to obtain both short and long-term clinical outcomes data on the Zimmer TM Glenoid by analysis of standard scoring systems and radiographic analysis. The TM Glenoid Component is intended to function within Zimmer, Inc.'s Bigliani/Flatow (B/F) Complete Shoulder Solution. The device is a monoblock glenoid component comprised of a Trabecular Metal base, and is designed to interface and articulate with Zimmer, Inc.'s B/F humeral components. The Trabecular Metal Glenoid is designed with an articular surface that is manufactured from ultra-high molecular weight polyethylene (UHMWPE). The base of the implant has a cruciate TM keel that provides stability and initial fixation using a press-fit between the implant and the bone. Long-term fixation is provided by biological ingrowth into the TM material. Surgical fixation of the trabecular metal device will be obtained via press-fit. Surgical fixation of the comparison all-polyethylene glenoid component will be with Palacos/CoPal bone cement

This is a multi-centre, randomized controlled study to evaluate the clinical and radiological performance of the TM Glenoid in a series of patients with adequate glenoid bone stock receiving a total shoulder replacement. The comparison group will be a consecutive series of randomized patients with implanted cemented all-polyethylene glenoid component. This study will be descriptive in nature and seeks to demonstrate the superiority (or non-inferiority) of the TM Glenoid over cemented all-polyethylene glenoid components.

Inclusion criteria

• Age - 18 years minimum and 80 years of age maximum.
• Gender - male and female.
• Primary Diagnosis: Primary Glenohumeral Osteoarthritis
• Informed Consent - patient has signed a 'Patient Informed Consent form'
• Surgery date: Beginning on January 1, 2012
• KEY Inclusion Criteria: The critical inclusion criteria for patient selection for TM or Cemented glenoid prosthesis are based on adequacy of glenoid bone stock/quality at time of implantation. Pre-operative CT scans and intra-operative decision of the surgeon at time of surgery will determine the issue of bone stock/quality.

Exclusion criteria

• Age > 80 years
• Significant Bone Loss (classified as concentric vs eccentric; contained vs uncontained) on pre-operative CT scan requiring cemented prosthesis.
• Evidence of major joint trauma, infection, avascular necrosis, cuff tear arthropathy, inflammatory arthropathy, chronic dislocation, massive rotator cuff tear or previous shoulder surgery (other than arthroscopic debridement)
• Preoperative computed tomography scans of the shoulder that showed insufficient glenoid bone stock to allow for implantation of a glenoid prosthesis
• Active joint or systematic infection, significant muscle paralysis, or Charcot arthropathy
• Life expectancy of less than 2 years or unacceptably high operative risk
• Inability to speak or read English
• Psychiatric illness or cognitive deficit that precluded informed consent
• Unwillingness to be followed up for 5 years