Outcomes following a Multimodal Pain Protocol in Total Knee Arthroplasty

Participants will be divided into 2 main cohorts for study purposes. The first cohort will be a retrospective review of all total knee replacements performed within the last year (2011) at Cairns Base Hospital. It is hoped to recruit approximately 100-150 participants into this study. This cohort will not adhere to our multi-modal analgesic pathway. There will therefore be a wide array of anaesthesic modalities ranging from central catheter techniques such as spinals, epidurals, combined spinal-epidurals (CSE), to general anaesthesia (GA), to peripherally placed catheters such as femoral nerve blocks (FNB) or fascia iliaca blocks (FIB) applied to this cohort of patients. The second cohort of participants will be a prospective review of all total knee replacements performed at Cairns Base Hospital from the date of ethics approval onwards for however long it is required to recruit approximately 100-150 participants into this cohort. The second cohort of patients will strictly adhere to the multi-modal analgesic pathway described below. Participants will have either a GA or single shot spinal anaesthetic given at the discretion of the anaesthetist. Participants will also receive a single shot femoral nerve block prior to commencement of surgery while in the induction bay administered by the anaesthetist. During the surgery, the surgeon will inject local anaesthetic (Bupivocaine 0.2%/Ropivocaine 0.5% - 100ml) into the posterior capsule of the knee prior to commencement of cementing the knee. A Total Knee Arthroplasty is a lengthy procedure with complicated steps lasting approximately an hour and a half to 2 hours depending on surgeon skill, instrumentation and deformity of the knee. After the patient has been anaesthetized, the patient will be prepped & draped, after which a midline parapatella approach is performed down to the knee joint. Osteophytes will be removed and the patella subluxated laterall to allow full access to the femur and tibia. The ACL is dissected out, and the osteoarthritic portions of the distal femur and proximal tibia will be resected. Specific jigs/guides will be utilised to allow for correction of varus/valgus or rotational deformity of the knee and to shape the femur and tibia to receive the definitive implants. Trial implants will be inserted first to determine if any further correction is required before the definitive implants are placed. If adequate, the knee joint is thoroughly washed and depending on the implants utilised, cement may be used to hold the femoral component in place or there may be a specific hydroxyapatite coating on the femoral component allowing bony ingrowth. The tibial component is always cemented in place. A highly cross-linked polyethylene insert is then placed between the femoral and tibial components to allow gliding of the implants. The knee is then washed again, and the retinaculum repaired over the knee joint, the wound closed in layers and a dressing placed over the wound. Patient’s will then be placed on a Patient Controlled Analgesia (PCA) overnight and be reviewed by the Acute Pain Team/Service in the morning. Formal bloods and x-rays will be ordered and participants will be visited by the physiotherapist during the day. Mobility will be determined by whether patient achieved transfer from bed – chair whether with minimal/heavy assistance, and whether patient was able to mobilise with aid of a frame/rollator with guidance from the physiotherapist.