Compare the clinical and patient reported outcomes of the Vanguard XP Knee System to the Vanguard CR Knee System in patients with antero-medial osteoarthritis of the knee with an intact anterior cruciate ligament.

The purpose of the proposed ALLIKAT study (All Ligaments Left in Knee Arthroplasty Trial) is to evaluate the early outcome of a Total Knee Replacement device that retains both cruciate (Vanguard XP) by comparing it with a control group of patients implanted with an established single cruciate retaining device (Vanguard CR). The study also aims to examine short and long term descriptive cohort outcome data. A small preference cohort group of 60 patients receiving the Vanguard XP Knee System will be recruited alongside the RCT group. This data will be used to confirm the external validity of the RCT group and to contribute to the safety data for the British Orthopaedic Association's Beyond Compliance Programme.

Evaluation will include intra-operative and post-operative complications, longer term survivorship and patient reported outcome measures.

Inclusion Criteria:

• Primary Osteoarthritis of the knee involving one or more compartments of the joint.
• Intact Anterior and Posterior Cruciate Ligaments.
• Intact collateral ligaments.
• Correctable coronal deformity.
• No more than 15 degrees of fixed flexion deformity.

Exclusion Criteria:

• Age under 18 years.

• Revision knee replacement surgery.

• Rheumatoid Arthritis.

• Traumatic aetiology.

• History or clinical signs of ACL rupture.

• Previous arthroscopy related to ACL injury or reconstruction.

• Correction of a flexion contracture that may require extensive resection of distal femur.

• Altered pain perception and / or neurologic affection (for example as a complication arising from diabetes).

• Unable to consent for themselves.

• Patients with language or cognitive issues that may prevent them completing the follow up requirements.

• Contraindications for the device:

  • Cementless application of components.
  • BMI ≥40 kg/m2.
  • Use of Anterior Stabilized Bearings.
  • Patients with severe pre-operative varus or valgus deformity ≥ 15 degrees.
  • Correction or revision of previous joint replacement procedure on index knee.
  • Infection.
  • Sepsis.Osteomyelitis.
  • Osteoporosis (requiring treatment).

• Relative contraindications include:

  • Unco-operative patient or patient with neurologic disorders who is incapable of following directions.
  • Osteoporosis.
  • 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, neuromuscular disease.
  • Incomplete or deficient soft tissue surrounding the knee, including the anterior cruciate ligament.