Vanguard™ Deep Dish Rotating Platform Knee Clinical Evaluation

Vanguard™ Deep Dish Rotating Platform Knee Clinical Evaluation

This study is being conducted on the Vanguard™ Deep Dish Rotating Platform (DD RP) to evaluate the clinical efficacy of the DDRP components.

This study is designed to evaluate the safety and efficacy of Vanguard™ Deep Dish Rotating Platform Knee (mobile bearing knee) as compared to Vanguard Cruciate Retaining Knee (fixed bearing knee). This trial was conducted as the randomised, controlled study.

Implant loosening and polyethylene wear in fixed-bearing knee prostheses were recognized as major causes of late failure. The mobile bearing knee have the theoretical advantages of potentially minimizing the polyethylene wear and reducing implant to bone interface stress in order to reduce the incidence of implant loosening. Therefore, the aims of this study were to prove the Vanguard deep dish rotating platform knee is at least as effective in clinical outcome as the widely used current design of knee replacement and better in long term survivorship.

The efficacy of the device was determined by the relief of pain, restoration of function and range of motion. The durability of device was determined by the absence of revision/removal and radiological integrity. To assess the safety of the device, all post operative complications were recorded either device related or otherwise. Patient satisfaction was determined by answers to patient outcome questionnaires (Oxford Knee Score, WOMAC and Lower Extremity Activity Scale).

Between June 29, 2009 and March 5th 2012, 326 cases were enrolled in the study. In total 117 cases were implanted with the Vanguard fixed bearing cruciate retaining knee; the control arm, and 209 cases were implanted with the Vanguard DDRP. All of these patients fulfilled the inclusion/exclusion criteria. From the 4 participating sites, 2 of them (both located in the Netherlands, Zuyderland Hospital and Bravis Hospital) performed a randomized controlled trial (RCT). In the RCT, 40 cases were assigned to the Trial Arm (Vanguard DDRP), and 51 to the control arm (Vanguard CR). The UK site enrolled cases only in the Vanguard DDRP arm and the French site enrolled in both arms, but non-randomized. Total 326 patients are enrolled in the study.

Inclusion Criteria:

• Patients with a pre-operative Knee Society Score of < 70
• Patients scheduled to undergo primary total knee replacement with any of the following indication: Painful and disabled knee joint resulting from osteoarthritis, Traumatic Arthritis, Rheumatoid Arthritis; One or more compartments are involved
• Need to obtain pain relief and improve function
• Ability and willingness to follow instructions, including control of weight and activity level, and to return for follow-up evaluations
• A good nutritional state of the patient
• Full skeletal maturity of the patient, patients who are at least 18 years of age
• Patients of either sex
• Consent form read, understood, and signed by patient

Exclusion Criteria:

Absolute contraindications include the following diagnoses:

• Patients with a pre-operative Knee Society Score of >= 70
• Infection
• Osteomyelitis
• Previous partial or total prosthetic knee replacement on the operative side
• Patients who are less than 18 years of age
• Sepsis
• Patients who had body mass index >= 40

Relative contraindications include the following factors:

• Uncooperative patient or patient with neurological disorders who are incapable of following directions or who are predictably unwilling to return for follow-up examinations
• Osteoporosis or marked bone loss, which may preclude proper fixation of the prosthesis
• Metabolic disorders, which may impair bone formation
• Osteomalacia
• Distant foci of infections, which may spread to the implant site
• Rapid joint destruction, marked bone loss, or bone resorption apparent on roentgenogram
• Vascular insufficiency, muscular atrophy, or neuromuscular disease in the affected limb.
• Incomplete or deficient soft tissue surrounding the knee