Below are highlights from the 2015 American Association of Hip and Knee Surgeons (AAHKS) Meeting held November 5-8, focusing on perioperative considerations.
OBESITY: The Stanford Group presented a study showing increased rate of loosening and failure in obese individuals. The onset of failure was sooner seen in obese individuals, particularly in patients who had a combination of obesity plus metabolic syndrome, which is characterized by obesity with hypertension, sleep apnea, dyslipidemia, and sleep apnea.
DVT PROPHYLAXIS: Multiple papers confirmed stratification of patients with potential risk for DVT. Low risk patients are classically treated with aspirin 325 b.i.d. There is work that is ongoing to determine if 81 mg aspirin b.i.d. is as affective as 325. The Rothman Clinic reported on risk assessment using a smart phone app VTEstimator, which rates patients as either high or low risk. Factors associated with increased risk were those with hypercoagulability, i.e. factor V Leiden, history of prior DVT, ongoing malignancy, or COPD.
PHYSICAL THERAPY: The Rothman Clinic presented a study where they found no benefit from formal physical therapy with the majority of their total hip patients. Their prior protocol was 2 weeks of home physical therapy followed by 8 weeks of outpatient formal therapy at a cost of roughly $5000 per patient. Calculating that 350,000 total hip replacements were done per year, if outpatient therapy for hips was eliminated, that would be a 1.5 billion dollar savings. They agreed that some patients do need the benefit of physical therapy, but in young healthy people, it can probably be avoided.
CROSS-LINKED POLYETHYLENE: The MGH group presented 2 papers with 13-year follow-up on highly cross-linked polyethylene with 10 megarads. They noted an incredibly low wear rate of 0.004 mm per year. They found no lysis and no mechanical failures at 13-year follow-up. There is consensus that cross-linked polyethylene will substantially improve outcomes, at least over the first 15 to 20 years after surgery.
INFECTIONS: Craig Devalle presented a paper looking at a group of patients who had gone through a 2-stage reimplantation for treatment of infection. They had 53 patients that were treated with oral antibiotics, organism-specific, for 3 months after completing their 3 to 5 day of IV antibiotics after implantation in 41 patients who stopped antibiotics after the cultures from surgery came back negative. The re-infection rate at 18 months was 5% for the patients who received 3 months of oral antibiotics and 20% for the patients who did not receive oral antibiotics. They concluded that it is appropriate to treat patients with 3 months with oral antibiotics after reimplantation of the knee.
CORTISONE INJECTION PRIOR TO JOINT REPLACEMENT: There were 2 papers reviewing the increased risk of prosthetic joint infection after cortisone injection. The consensus was cortisone injection should not be given closer than 3 months prior to hip or knee replacement because of the increased odds of infection if it is done in a shorter time frame.
TOTAL KNEE ALIGNMENT: Two papers looked at kinematic alignment versus standard alignment and found no difference and the consensus was that kinematic alignment increases the risks of varus malalignment of the implants.
Obesity: The majority of people shoot for a BMI less than 35. Those with a higher BMI have increased wound problems, surgical site infection, increase rate of readmission and reoperation, and an increased risk of cup malpositioning in total hips.
Diabetes: Consensus is we should shoot for A1c of 7, perhaps 8, in patients who were working diligently and cannot seem to get it lower. The goal in the perioperative period is to keep the glucose less than 200 and it was recommended that we check this in the preop area, the PACU, and then AC and HS.
NICOTINE: Though we should aim to have all patients quit, if they cannot, then they can use a patch or gum which at least gets rid of some of the additives that are also in cigarettes. There is data to suggest that if they stop for 4 to 8 weeks, many of the parameters will improve after surgery.
MALNUTRITION: Parameters to evaluate include albumin less than 3.5, total lymphocyte count less than 1500, and transferrin levels less than 200. If patients have these, they should be referred to nutritionists for dietary consultation. People felt that orthopods paying attention to obesity, diabetes, nicotine, and malnutrition and getting patients in appropriate programs tend to engage the patient. Studies indicate that patients who are engaged in trying to improve themselves prior to surgery have better outcomes.
OUTPATIENT SURGERY: The goal is to choose patients who will not require medical management in the postoperative period, i.e. no coronary artery disease, congestive heart failure, a-fib, sleep apnea, and urinary retention as these typically will have problems. Patients should be less than 65 as Medicare currently does not have codes for this. A finger stick can be done in the office to rule out patients with anemia and either have them set up with Procrit 3 weeks prior to surgery or make sure they end up at the hospital, not the outpatient center. The most important message is having everybody on the same page as far as patient education and what the patient hears as far as recovery.
SURGERY: Appropriately selected patients have surgery with lidocaine spinal which lasts roughly an hour and a half. The surgery should not take longer than an hour. The patient goes to phase one at the outpatient center, spends approximately an hour there, is up sitting, eating ice chips, moving around. They then move to phase two after approximately one hour and there, the family is brought back to hear the instructions as the patient will generally not remember them; they start physical therapy, get up, walk around. They use Vicodin, Oxycodone, and Dilaudid for outpatient pain management. The Dilaudid is used as a crutch for pain crisis. After an hour and a half in phase one, they move to the physical therapy department where they continue walking, practice stairs, and the staff ensure that the patient is voiding well. The patient then goes home and is called the next day and day three by nurse managers.
TRUNNIONOSIS: There was a symposium on trunnionosis, which occurs with a titanium stem and cobalt chrome head. The incidence was estimated by Joss Jacobs to be less than 5%. It is higher with the dual modular necks, which have generally been abandoned. There was a question of whether or not we should abandon cobalt chrome heads, but the data does not support this. The majority of people in the American Joint Registry support using ceramic heads in patients less than 65 and cobalt chrome heads in patients over 65. There is some consideration for using a ceramic head if you are using a 36 mm head because of the strain on the trunnion. This is an evolving topic and we will find out more as time goes on.