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NCT Number: NCT02501733

Medacta GMK Sphere® Multicenter Post-Market Outcomes Study

This study is to average Forgotten Knee Score (FJS) of those patients receiving the Medacta GMK Sphere® knee at the two and five year time points. 70 subjects, enrolled at the data coordinating center in Medacta GMK Sphere® vs Posterior Stabilized study (WIRB Pro Num: 20141994) and randomized to the Sphere arm, will have their data utilized for this study.

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Key information

Conditions

Osteoarthritis Arthritis Joint Diseases Musculoskeletal Diseases Rheumatic Diseases

Age range

21 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Norhtwestern University, Chicago, Illinois, United States

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Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients willing to sign the informed consent
  • Patients able to comply with follow-up requirements including postoperative weight bearing restrictions and self evaluations.
  • Male and non-pregnant female patients ages 21 - 80 years of age at the time of surgery.
  • Patients requiring a primary total knee replacement.
  • Patients with a diagnosis of osteoarthritis (OA), traumatic arthritis (TA), or avascular necrosis (AVN).
  • Patients with intact collateral ligaments.

Exclusion criteria

  • Patients with inflammatory arthritis.
  • Patients that are morbidly obese, body mass index (BMI) > 40.
  • Patients with a history of total or unicompartmental reconstruction of the affected joint.
  • Patients that have had a high tibial osteotomy or femoral osteotomy.
  • Patients with neuromuscular or neurosensory deficiency, which would limit the ability to assess the performance of the device.
  • Patients with a systemic or metabolic disorder leading to progressive bone deterioration.
  • Patients that are immunologically compromised, or receiving chronic steroids (> 30 days).
  • Patients bone stock is compromised by disease or infection, which cannot provide adequate support and/or fixation to the prosthesis.
  • Patients with knee fusion to the affected joint.
  • Patients with an active or suspected latent infection in or about the knee joint.
  • Patients that are prisoners.

Treatment and study plan

Medacta GMK Sphere® Medial Knee Prosthesis

Device

There is no consensus within the Arthroplasty community as to whether a traditional post and cam-style Posterior Stabilized total knee device is superior to a medial-pivot, more congruent device. However, the majority of surgeons seem to prefer the former, though there is a minority that uses the latter device with great success.

To date, there have been few prospective trials directly comparing these devices, and none with the latest generation of Total Knee Arthroplasty implants. Almost all such studies have been retrospective and/or utilizing older generation devices.

Other names: Total Knee Arthroplasty, Total Knee Prosthesis

Primary outcomes

  1. Evaluate the change in Forgotten Knee Scores (FJS) of those patients receiving the Medacta GMK Sphere from baseline to years 2 and 5 post-operatively.

    Time frame: Baseline, 2 and 5 year time points

    Knee function-patients ability to forget the artificial joint in everyday life.

Secondary outcomes

  1. Total Knee Society Score (KSS)

    Time frame: Pre-operative, 6 weeks, 3-6 months, 1,2,3,4 and 5 years.

    Total Knee Society score questionnaire to assess pain and function

  2. Krackow Activity Scale (KAS)

    Time frame: Pre-operative, 6 weeks, 3-6 months, 1,2,3,4 and 5 years

    The Krackow Activity Scale (KAS) lower extremity activity scale.

  3. Radiographic Analysis

    Time frame: Pre-operative, 6 weeks, 3-6 months, 1,2,3,4 and 5 years

  4. AP long standing X-ray

    Time frame: Pre-operative and 6 weeks

    Determine degree of Varus or Valgus

Sponsors and collaborators

Lead sponsor

Medacta USA

Industry

Registry information

Official study title

Medacta GMK Sphere® Medial Pivot, Cruciate Substituting Multicenter, Post-Market Outcomes Study

Important dates

Study start
2015
Primary completion
2024
Study completion
2024
First posted
Jul 17, 2015
Registry last updated
Sep 25, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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