The Role of Intra-Operative Intracapsular Blocks in Post-Operative Pain Management Following Total Knee Arthroplasty
The Role of Intra-Operative Intracapsular Blocks in Post-Operative Pain Management Following Total Knee Arthroplasty
The purpose of this study is to use a new combination of anesthesia techniques in an attempt
 to minimize early pain after surgery and improve the patient's ability to participate more
 fully with physical therapy. Total knee replacement patients who participate will receive the
 standard anesthesia. This includes a spinal nerve block as well as a femoral nerve block. The
 study is looking at the added benefits of including an injection of numbing medication
 (Bupivicaine) to the back of the knee. This injection occurs during surgery. In order to
 compare the outcomes we will also have a group of patients who will receive a saline
 injection as opposed to the numbing medication. Patients are randomly assigned to a group.
 Outcomes are measured up until twenty-four hours following the surgery.
Research Summary

 Purpose of Study This prospective, randomized, blinded controlled trial will be conducted to
 evaluate post-operative pain control and physical therapy outcomes in primary total knee
 arthroplasty (TKA) with the use of spinal analgesia and intra-operative posterior capsular
 injections of ropivicaine 0.5% in conjunction with a continuous femoral nerve catheter.

 We believe the results of this study will show an improvement in pain control and physical
 therapy outcomes compared to traditional methods of analgesia in post-op total knee
 arthroplasty. To the best of our knowledge, there are no studies in the literature using this
 combination of femoral nerve analgesia and posterior capsular injection.

 Certainly regional anesthesia methods such as femoral nerve blocks used alone or in
 conjunction with sciatic nerve blocks have improved patient pain outcome measures in total
 knee arthroplasty. Several studies have shown a beneficial effect of intra-articular
 analgesia after capsular closure. We believe our study design will combine the beneficial
 effects of the aforementioned methods, and ultimately improve patient pain, therapy effort,
 and safety through less narcotic use.

 Our goal is to share these results in a peer-reviewed journal, and at national orthopaedic or
 anesthesia meetings. The data collected will ideally improve care and safety in the
 post-operative total knee arthroplasty patient.

 Background and Significance Post-operative pain control in total knee arthroplasty is an area
 of great study in the orthopaedic surgery and anesthesia literature. The use of
 spinal/epidural alone or in combination with regional anesthesia is well studied in the
 recent literature. These techniques have significantly improved patient pain management,
 physical/occupational therapy outcomes, and shortened time to discharge.

 Additionally, intra-articular injection of local anesthetic after capsular closure has been
 studied recently. Several studies have demonstrated a beneficial effect of intra-articular
 local anesthetic on pain outcome measures (6, 8, 9, 10, 15). Although other studies have
 reported more equivocal results. The impact of capsular analgesia has on post-operative pain
 is intriguing. Decreased afferent pain perception by the capsular nerves from local
 anesthetic may improve outcomes, especially in sensory distributions where regional
 anesthesia is inadequate or not performed.

 Much study has centered on regional anesthesia, specifically the use of single shot or
 continuous femoral nerve blockade (4, 5, 11, 14, 16). Such studies have demonstrated a
 statistically significant decrease in total narcotic use, sedation scores, and visual analog
 pain scores. Femoral nerve blockade is now an accepted method of post-op pain control in the
 total knee arthroplasty patient.

 Further investigation has centered on the addition of sciatic nerve blockade to femoral nerve
 block (1-3, 7, 12, 13). Several studies demonstrate a further improvement in pain outcomes
 compared to isolated femoral nerve anesthesia. Sciatic nerve blocks can slow physical therapy
 efforts secondary to a dense motor blockade. Equivocal results have been reported in other
 studies due to this motor block, however, the sensory component appears to provide improved
 pain outcome measures.

 Femoral nerve blockade is a well-accepted modality for analgesia in total knee arthroplasty.
 However, femoral nerve block alone does not provide adequate anesthesia to the posterior
 aspect of the knee. We believe that intra-operative injection of ropivicaine 0.5% into the
 posterior capsule will provide analgesia analogous to the sensory component of a sciatic
 nerve block, while eliminating the limiting effects of the motor blockade. The combination of
 femoral nerve block and intra-operative posterior capsular injection will ideally yield
 improved pain management and physical therapy efforts above a baseline femoral nerve block.

 Design and procedures This is a prospective double-blinded, randomized trial consisting of
 two study groups: posterior capsular saline injection (control), and the experimental
 posterior capsular ropivicaine 0.5% injection group. All patients will receive spinal
 anesthesia and a continuous femoral nerve block. Each group will include 45 patients (n = 90
 patients).

 All patients will have an elective primary total knee arthroplasty performed. No revision or
 bilateral cases will be included. Exclusion criteria will include patients with a known
 allergy to ropivicaine or fentanyl, a known history of narcotic abuse or chronic pain, a
 known diagnosis of peripheral neuropathy or complex regional pain syndrome, or a significant
 impediment to physical therapy participation.

 Following the informed consent process, patients will receive a continuous femoral nerve
 block via catheter placed by experienced regional anesthesiologists at our institution. Each
 patient will also receive spinal anesthesia for intra-operative pain control. A standard
 midline skin incision with medial para-patellar arthrotomy will be performed followed by
 implantation of either a Next Gen (Zimmer/Warsaw, IN), or Natural Knee II (Zimmer, Warsaw,
 IN), or Posterior Femoral Component (PFC) Sigma (DePuy, Warsaw, IN) system. Prior to surgery,
 patients will be randomized to the saline or ropivicaine groups. Both groups will receive
 their respective injection prior to implantation of the components.

 The posterior capsule of the knee will be divided in to four quadrants, each receiving a
 saline or ropivicaine injection per randomization. Safety measures will include standard
 pre-injection aspiration to check for vascular blush and intra-operative Doppler ultrasound
 to identify vascular structures in the posterior knee. Additionally, the anesthesiologist
 will not be blinded, as he/she will be responsible for assuring the appropriate medication is
 used, and will be closely monitoring for cardiac arrhythmias in the unlikely event that an
 intravascular injection occurs. Post-operatively, a standard bulky dressing will be applied.
 All patients will be weight bearing as tolerated post-operative day 1. A fentanyl PCA will be
 initiated in the PACU, and will be continued until post-operative day 2. Dosing will be
 calculated based on lean body mass. Continuous femoral nerve blockade will continue until
 post-operative day 2 as well.

 Outcomes will include total PCA narcotic use, visual analog pain scale with a diagram to
 localize pain, and Ramsey sedation scores. This data will be collected at the following
 intervals: in the PACU, 4, 8, 12, and 24 hours post-operatively. We will also measure
 post-operative day 1 knee range of motion, total ambulation distance, and time to straight
 leg raise. A standard, Institutional Review Board (IRB) approved, data collection sheet will
 be utilized.

 We hypothesize that total post-operative narcotic use, visual analog pain scores, and Ramsey
 sedation scores will be significantly lower in the study group (posterior capsular
 ropivicaine 0.5% injection). Additionally, we anticipate the knee range of motion, total
 ambulation distance, and time to straight leg raise to be significantly improved as well.
Inclusion Criteria:

 -  The subject is scheduled to undergo elective total knee replacement at Duke University
 Hospital.

 -  The subject has signed the written consent form.

 Exclusion Criteria:

 -  Known allergy to ropivacaine or hydromorphone.

 -  Known history of narcotic abuse or alcohol abuse.

 -  Known history of chronic pain.

 -  Known diagnosis of peripheral neuropathy or complex regional pain syndrome.

 -  Significant impediment to physical therapy participation.

 -  The surgery is a revision case.

 -  Patient is undergoing bilateral Total Knee Replacement.