A Single-Center, Epidemiological Study of the Survivorship of the DePuy Sigma HP Unicompartmental Knee Prosthesis

• Five-Year Survivorship [ Time Frame: Five Years Post-Op ] [ Designated as safety issue: No ]
  The primary endpoint of the study is to determine the five-year survivorship of the Sigma® HP Partial Knee System with failure defined as revision for any reason.
  
  

• Five-Year Survivorship Alternately Defining Failure and Two-Year Survivorship [ Time Frame: Two Years and Five Years Post-Op ] [ Designated as safety issue: No ]

  One secondary endpoint of the study is to determine the five-year survivorship of the prosthesis with alternately defining failure as: failure of implant, failure secondary to infection, failure secondary to progression of arthritis, failure secondary to periprosthetic fracture.

  We also want to determine the two-year survivorship with failure defined as revision for any reason.

  
  
• Functional Outcomes [ Time Frame: Five Years Post-Op ] [ Designated as safety issue: No ]
  Another secondary endpoint of the study is to analyze the functional outcomes for five-year data based on the Knee Society score and the KOOS (Knee Injury and Osteoarthritis Outcome Score) score, reported as changes from the pre-operative score. By using both rating systems, an appropriate evaluation of the functional outcome of the surgery should be obtained.
  
  
• Radiographic Outcomes [ Time Frame: Pre-Operatively, Two and Five-Year Post-Op ] [ Designated as safety issue: No ]
  Another secondary endpoint of the study is to determine the radiographic outcomes based upon the radiographic assessment using the Knee Society scoring system, reported as changes from the pre-operative assessment. Additionally, we want to radiographically assess lucencies at the bone cement and implant cement interface to measure wear and loosening of the prosthesis.
  
  
• Adverse Advents [ Time Frame: Post-Operatively ] [ Designated as safety issue: Yes ]
  We also want to examine the type and frequency of adverse events as a secondary endpoint of the study. Safety will be evaluated with summary of adverse events.
  
  

This study is an epidemiological Level IV-Case Series clinical study that will study the survivorship of the Sigma® HP Partial Knee System in a consecutive series of patients. All patients who received the Sigma® HP Partial Knee System between August 21, 2008 and October 31, 2009 will be available to include in the study. Data will be collected preoperatively, intra-operatively, and post-operatively at intervals of 6 weeks, 6 months, 1 year, 2 years, and 5 years. Data will be analyzed for survivorship status at the 2- and 5-year follow-up visits. Other data, including functional outcomes, radiographic outcomes, and wear will be analyzed at the 5-year follow-up visit. Subjects will participate in the study for five years after their surgery.