Antero-Posterior Knee Stability

Study Overview
=================
Brief Summary
-----------------
A retrospective one-time evaluation of total knee patients one year or more postoperative, to compare antero-posterior (AP) stability with the TELOS Stress device/stress x-rays and clinical outcomes. Multiple implant brand/models will be included in the study.

Official Title
-----------------
Antero-Posterior Knee Stability With Medial-Pivot, Cruciate-Substituting, and Posterior-Stabilized Total Knee Arthroplasty: A Retrospective Study

Conditions
-----------------
Osteoarthritis, Total Knee Arthroplasty, Stability, Knee Osteoarthritis

Intervention / Treatment
-----------------
* Other: Stress X-Ray


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients willing to sign the informed consent. Patients able to comply with study requirements including stress x-rays and self-evaluations. Male and non-pregnant females ages 21 - 80 years of age at the time of surgery. Patients who have undergone a primary total knee replacement, are one year or greater postoperative, and are not having any evidence of failure of their implants. Patients with a diagnosis of osteoarthritis (OA), traumatic arthritis (TA), or avascular necrosis (AVN). Patients with intact collateral ligaments. Range of motion within five degrees of full extension and a minimum of 120 degrees of flexion. Exclusion Criteria: Patients with inflammatory arthritis. Patients that are morbidly obese, body mass index (BMI) > 40. 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), excluding inhalers. 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.

Ages Eligible for Study
-----------------
Minimum Age: 21 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Medial-Pivot Knee Prosthesis<br> | Other: Stress X-Ray<br>* Antero-posterior stability of the knee measured with stress x-rays using the TELOS Stress device in 45° and 90° flexion<br>|
| Posterior-Stabilized Knee Prosthesis<br> | Other: Stress X-Ray<br>* Antero-posterior stability of the knee measured with stress x-rays using the TELOS Stress device in 45° and 90° flexion<br>|
| Cruciate-Stubstituting Knee Prosthesis<br> | Other: Stress X-Ray<br>* Antero-posterior stability of the knee measured with stress x-rays using the TELOS Stress device in 45° and 90° flexion<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Measurement of antero-posterior stability of the knee with stress x-rays. | Antero-posterior stability of the knee will be measured with stress x-rays using the TELOS Stress device in 45° and 90° flexion. Stress x-rays will be obtained during a single visit for subjects 1 year or greater post-operatively. | 1 year post-operative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Knee Society Score (KSS) | Clinical outcomes will be evaluated via the Knee Society Score (KSS) obtained during a single visit for subjects 1 year or greater post-operatively. The KSS is subdivided into a Knee Assessment score which rates only the knee joint itself, and a Functional Assessment score which rates the subject's ability to walk and climb stairs. Both scores range from 0-100, with a higher score indicating a better outcome. | 1 year post-operative | 
| Lower Extremity Activity Scale (LEAS) | Clinical outcomes will be evaluated via the Lower Extremity Activity Scale (LEAS) obtained during a single visit for subjects 1 year or greater post-operatively. The LEAS scale range is 1-18, with a higher value indicating a higher level of activity. | 1 year post-operative | 
| Forgotten Joint Score (FJS) | Clinical outcomes will be evaluated via the Forgotten Joint Score (FJS) obtained during a single visit for subjects 1 year or greater post-operatively. The FJS total score range is 0-100, with higher scores indicating a higher degree of forgetting the artificial joint, that is, a lower degree of awareness. | 1 year post-operative |