Recently there has been interest in an alternative method of aligning a total knee arthroplasty (TKA) referred to as kinematic alignment. The theoretical appeal of this method is that alignment of each patient's knee can be individualized through the use of preoperative imaging and computer software, with the goal of achieving pre-arthritic alignment through restoration of the axes of rotation of each particular knee. Clinical studies have evaluated the outcomes of this new alignment technique, but to date there have been no randomized controlled trials comparing kinematic alignment to mechanical alignment. This randomized controlled trial was conducted to compare kinematically aligned and mechanically aligned TKA outcomes of knee pain, function and motion at two years' post-op, along with a comparison of limb, knee, and implant alignment of the two methods. Forty-four patients were surgically treated with kinematically aligned TKA (figure 1) with the use of patient specific guides, and forty-four patients were surgically treated with mechanically aligned TKA with the use of conventional instruments. All patients underwent CT long leg scanograms after surgery, and outcomes data were collected at a minimum of 2 years. The patient, radiographic evaluator, and clinical evaluator were blinded as to the alignment method.Introduction:
Methods and Materials:
The development of the High Reliability Organization focused on safety in organizations such as nuclear power plants, to avoid catastrophes in an environment where accidents might be expected due to risk factors and complexity. (Figure 1) The Agency for Healthcare Research and Quality applied High Reliability Concepts to hospitals in an effort to improve safety and quality. The Institute for Healthcare Improvement has further expanded this approach to include establishing processes to ensure highly reliable care through analysis, design or redesign, using a model for improvement, and supported by technology and the physical environment. These concepts can be applied to total knee replacement by identifying key processes, conducting regular measurement and analysis, and ensuring daily problem solving to create and maintain process reliability. The application of patient specific technology to our conventional total knee replacement procedures creates an opportunity to improve both quality and safety in total knee replacement procedures. Preoperative imaging and use of computer software allows the surgeon to develop an individual blueprint for each operative procedure. A patient specific cutting guide is fabricated for use in surgery. Intra-operative measurement of bone cuts with comparison to the planned blueprint allows correction of inaccurate bone cuts during surgery. Post operative CT scanning provides a final accurate check of limb, knee and implant alignment in 3 dimensions, with comparison to the preoperative plan. Feedback from the surgeon to the engineers involved in the planning process allows daily improvement of the guide fit, cut accuracy and accuracy of limb, knee and implant alignment for these procedures. Patient reported outcome measures such as the Oxford Knee Score or WOMAC score can be carried out preoperatively and at 6 months post op, to assess reduction of pain and functional improvements resulting from the operative procedure. Ongoing annual patient surveillance using the 12 questions on the Oxford Knee Score, one question about satisfaction, and one question asking if the patient has undergone further surgery on the operative knee, can help assess the durability of the patient outcomes and the longevity of the prosthesis. Use of patient specific cutting guides, coupled with preoperative software for planning a kinematically aligned TKA, has demonstrated improved RCT outcomes at the Phoenix VA. Figure 2 compares the distribution of WOMAC scores for kinematically aligned and mechanically aligned TKA. Individualizing the alignment for each patient has narrowed the distribution of the scores, with 87% of the kinematically aligned scores better than the median score for mechanically aligned patients. There have been additional recent preoperative, perioperative and postoperative processes and checklists designed to increase quality and safety of TKA. Medical team training for preoperative briefing and post operative debriefing, use of the AAOS new STEPPS training program, monitoring post operative results with the NSQIP/VASQIP program and database give us additional tools to improve safety and quality. Coupled with patient specific alignment technology, I believe we currently have an excellent opportunity to move toward High Reliability in total knee replacement.
