Anterior Knee Pain in Mobile Bearing Versus Fixed Bearing in TKA

Effect of Using Mobile Bearing on the Incidence Rate of Anterior Knee Pain in Primary Total Knee Arthroplasty Without Patellar Resurfacing (A Randomized Controlled Clinical Trial)

Osteoarthritis is the most common cause of chronic joint disease, and its incidence has increased due to the high average life expectancy, in addition to the high incidence of obesity. Total knee arthroplasty is currently an accepted treatment for severe degenerative conditions and there are various implant systems with special features depending on component geometry, degree of fit of the articular surfaces, and fixation techniques. A tibial component with mobile polyethylene has been developed as an alternative to fixed polyethylene because it has theoretical advantages in terms of increasing the range of motion, reducing wear conditions, and reducing the incidence of anterior knee pain when the articular surface of the patella is not resurfaced.

The study is a randomized controlled clinical trial where the sample will be collected within one year from the date of approval of the Scientific Research Council at Damascus University. The sample consists of a group of patients who will undergo a total primary knee arthroplasty without patellar resurfacing following primary arthritis knee. The patients will be randomly divided into two groups. The first will be a primary total knee arthroplasty with a mobile bearing, and the second group with a fixed bearing. Then the patients will be followed for at least one year. The data of the patients included in the study will be collected before the surgical operation, then the surgery; followed up for at least two years after it, and then compared between the two groups in terms of a range of motion and functional and clinical results according to the Knee Society Score (KSS) and the anterior knee pain scale, and patient satisfaction assessment according to the Forgotten Joint Scale (FJS).

The prostheses will be cruciate scarifying cemented DePuy Synthes PFC Sigma with a Mobile Bearing system without resurfacing the patella.

The prostheses will be cruciate scarifying cemented DePuy Synthes PFC Sigma with a Fixed Bearing system without resurfacing the patella.

Anterior knee pain will be assessed by the clinical anterior knee pain rating system described by Waters and Bentley (AKPS). The scale is composed of 13 items that evaluate subjective symptoms and functional limitations. The minimum score is 0 points and the maximum score is 100 points. An athlete with no sign of anterior knee pain would have a score of 100. All subjects with a positive AKPS (score less than 100) underwent a further assessment to determine patellofemoral pain diagnosis.

Clinical and functional outcomes will be assessed by Knee Society Score (KSS). The knee society score (KSS) contains questions in 2 sections: knee joint (pain, range of motion, stability) and function (walking distance, ability to climb stairs). When calculating the score, deductions are taken for assistive devices and flexion contractures, misalignment, or extension lag. The Knee Society Score is divided into three sessions: it consists of the Knee Score (100 points), the Knee Function (100 points), and the patient classification system. The classification system separates the patients into three categories depending on their medical conditions - A: unilateral or bilateral (contralateral knee operated successfully); B: unilateral -contralateral knee symptomatic; C: multiple arthritis. The two scores are initially marked at zero and points are assigned or deducted according to specific criteria.

Patient satisfaction will be assessed by Forgotten Joint Scale (FJS). The FJS-12 consists of twelve equally-weighted questions that are each answered on a five-level Likert scale aimed to measure patient satisfaction. The questionnaire was developed with the consideration that joint awareness is a very important and highly discriminative outcome parameter, especially in patients with good-to-excellent joint function. Answers to each question are individually scored and summed to create a raw composite score that is normalized to range from 0 (worst condition) to 100 points (best condition)

Inclusion Criteria: Patients with expected primary total knee arthroplasty Exclusion Criteria: Mediolateral instability Infective arthritis Severe deformity Revision Patients with severe obesity according to the Body Mass Index (BMI < 35).

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