In Vivo Arthroscopic Behavior of the Infrapatellar Plica of the Knee

Study Overview
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Brief Summary
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Anterior knee pain has been an enigmatic problem for orthopedic surgeons. Recent studies, as well as the clinical observation of the principle investigator have suggested that arthroscopic resection of the infrapatellar plica (IPP), a vestigial remnant from embryonic development of no known clinical or biological significance, may eliminate this pain. The mechanism whereby this pain is related to the IPP is unclear. This study will document the mechanical behavior of the IPP, its kinematics, as recorded on video among a group of subjects who are undergoing arthroscopy. Radiographic visualization of the observed behavior will be obtained by injection of contrast material, and then fluoroscopic recording of a standard series of motions. The plica will then be resected to avoid any possibility of residual symptoms related to its presence. Further fluoroscopy of the knee without plical attachment, will allow the kinematic behavior to be assessed. The procedure will then be terminated.

Detailed Description
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The infrapatellar plica (IPP) of the human knee is vestigial remnant of the embryologic division between the medial and lateral compartments of the knee, present in 85.5% of knees1, felt by some to be of no clinical significance other than acting as a block to visualization an movement during arthroscopy.2 S.J. Kim 3,4, C.R. Boyd 5, and B. Demirag 2006 have documented successful relier of anterior knee pain after resection of the IPP. This study seeks to assess the relationship between knee motion, activation of the extensor apparatus, and the IPP, in essence, the kinematics of the contents of the anterior compartment of the knee. The hypothesis to be evaluated is: the infrapatellar plica is a structure of fundamental biomechanical significance, allowing the transmission of force from the extensor apparatus to the distal femur through the fat pad, and acting as a restraint and a modulator of fad pad mobility. Subjects will be identified by the PI at their office visit. The subject will be consented. The consent will be discussed and verified in a second office visit before surgery. The subject will undergo arthroscopy specifically directed toward identifying and treating known pathology. Once this is finished, if an IPP is present, it will be injected with radiographic contrast material. A series of maneuvers will be performed involving passive and active motion of the knee and active contraction of the quadriceps apparatus. Videotape recording and fluoroscopy will be undertaken. The plica will be removed. Another fluoroscopy will be performed. The patient will be followed according to the standard practice for arthroscopy and the defined pathology.

Official Title
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In Vivo Arthroscopic Behavior of the Infrapatellar Plica of the Knee

Conditions
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Anterior Knee Pain Syndrome

Intervention / Treatment
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* Procedure: observation of the behavior of the infrapatellar plica


Participation Criteria
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Eligibility Criteria
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must be Healthy subject must be >18 years of age, skeletally mature must bePending knee joint arthroscopy. may not have Active infection

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 1<br>observation of the behavior of the infrapatellar plica | Procedure: observation of the behavior of the infrapatellar plica<br>* Local anesthesia using bupivicaine will be initiated. The IPP, if present will be injected with contrast material. In order to minimize discomfort, lidocaine 1%, in as small a volume as possible, will be injected into the fat pad under direct vision to avoid any intra-articular damage from the #25 needle. Radiographic visualization will be verified and the knee taken through a full range of passive and active exercises. Active quadriceps contraction in the subject will be performed at 0, 15, 30 60 and 90 degrees of flexion. In so far as is technically possible, the behavior of the IPP will be videotaped and recorded on lateral fluoroscopy.<br>* Other names: Knee surgery;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants With Successful Recording. | Observe the behavior of the IPP of the knee by fluoroscopy. A complete recording was obtained in 2 patients: this implied that the plica,central body, and fat pad were visualized. The patients then completed a series of manouevres which demonstrated the mechanical behavior of the infrapatellar plica-fat pad complex. | During procedure, on average one hour. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Knee physiology, Anterior compartment knee, Infrapatellar plica, Ligamentum mucosum, Enthesis organ, Fat pad of the knee, Patellofemoral kinematics