A Prospective Randomised Control Trial Comparing the Effect of Functional Alignment with Mechanical Axis Alignment on Outcomes after Total Knee Arthroplasty.

1. Brief Name This trial is studying the difference between the two knee alignment arthroplasty theories of mechanical alignment (MA), and functional alignment (FA). 2. Why There are no prospective studies looking at Functional alignment. Prospective studies comparing functional outcomes between the MA and KA groups have been performed but the main limitation of these studies has been the inability to accurately measure the desired deviation from neutral alignment as well as achieving the implant position to a high degree of accuracy. There is a paucity of studies using standardised techniques for intraoperative alignment and limited data relating these findings to clinical outcomes with long- term follow up. There is a need for high quality evidence on the clinical and radiological benefits of functionally aligned TKA. This study would show if there is any superior outcomes to be obtained from functional alignment. Clinical and functional outcomes should also be correlated to longer-term outcomes to better establish the “safe zone” for functional alignment. Currently the vast majority of TKA throughout the world is undertaken utilizing MA alignment. Any change to a newer technique from the current ‘gold standard’ would need to be justified by improved clinical outcomes as there is no long term longevity data for Functional Alignment. Both surgeons and patients are only able to consider the relative risks and benefits of this technique once they are defined by sound scientific evidence. This study will contribute to the body of this evidence. 3. What Materials: Knee Arthroplasty implants and surgical planning device 212698 - Stryker Australia Pty Ltd - TRIATHLON FEMORAL COMPONENT CRUCIATE RETAINING (CR) -Uncoated knee femur prosthesis 212701 - Stryker Australia Pty Ltd - TRIATHLON X3 ASYMMETRIC PATELLA - Polyethylene patella prosthesis 212702 - Stryker Australia Pty Ltd - TRIATHLON X3 SYMMETRIC PATELLA - Polyethylene patella prosthesis 213155 - Stryker Australia Pty Ltd - TRIATHLON FEMORAL COMPONENT POSTERIOR STABILISED (PS) -Uncoated knee femur prosthesis 216480 - Stryker Australia Pty Ltd - TRIATHLON X3 CRUCIATE RETAINING (CR) TIBIAL INSERT - Prosthesis, knee, internal, insert component 218001 - Stryker Australia Pty Ltd - TRIATHLON UNIVERSAL TIBIAL BASEPLATE - Uncoated knee tibia prosthesis, metallic 218019 - Stryker Australia Pty Ltd - TRIATHLON X3 CONDYLAR STABILISING (CS) TIBIAL INSERT - Prosthesis, knee, internal, insert component 218200 - Stryker Australia Pty Ltd - TRIATHLON X3 POSTERIOR STABILISED (PS) TIBIAL INSERT - Prosthesis, knee, internal, insert component Styker MAKO robotic arm (Stryker MAKO, Fort Lauderdale, FL). Patient PROMS - Forgotten Joint Score: The “Forgotten Joint” as the Ultimate Goal in Joint Arthroplasty: The Journal of Arthroplasy Volume 27, Issue 3. Pages 430-436. E1, March 2012. H Behrend et.al. - EQ5D-5L: https://euroqol.org/ - Oxford Knee Score: http://www.isis-innovation.com/outcomes - VAS Pain: Socrates: Copyright Ortholink. Pty Ltd 1997 - KOOS Jr: Validation of the KOOS, JR: A Short –form Knee Arthroplasty Outcomes Survey Clin Orthop Relat Res (2016) 474:1461-1471 Stephen Lyman PhD et al. - Kujala Anterior Knee Pain: https://www.orthotoolkit.com/kujala/ - Likert Scale 4. Procedures Patient Outcome Testing Tools a. Hand Held Dynamometer Testing, Lachmeter Arthometer Testing, 30 Second Sit to Stand Test. b. Surgical Planning i. All Patients will have pre-operative CT scan for planning as per current standard technique. ii. Prior to surgery Patient’s pre-operative plan will be formulated on the basis of their randomisation. iii. The control group will be planned to mechanical axis alignment. 1. To do this the tibia will be sized to best match with the tibial plateau size without more than 2mm overhang anterolaterally or posteriorly and no overhanging of cortices medial and laterally. The coronal angulation of the tibia will be 0° of varus/valgus and posterior slope will be 3°. Resection depth will be set to a depth of 7mm maximal resection. 2. The femur will initially be planned with the same size as the tibia and 8mm resection depths posteriorly and distally. Coronal angulation will be zero degrees varus/valgus and flexion of 3° for males and 5° for females. Size is then adjusted to allow best match to condylar radius of curvature. Femoral rotation will be set to parallel to surgical epicondylar axis. Femoral flexion angle is then altered within the range of 0-7° to optimise the anterior cut exit point. If unable to accommodate size without notching anterior cortex or having the tip of the implant achieving bony contact, size will be altered to achieve this. Medial lateral width of component will not overhang distal femur or will be downsized. iv. The investigation group will be planned with Kinematic Axis alignment. This will be changed to functional alignment intra-operatively once soft tissue balance assessed. 1. To achieve this the tibia will be sized to best match with the tibial plateau size without more than 2mm overhang anterolaterally or posteriorly and no overhanging of cortices medial and laterally. The resection depths will be set to 7mm medially and laterally. (N.B. This may exceed 6° of varus angulation but this will be adjusted intra-operatively). 2. The same size femur is then used as starting size. 6.5mm resections are planned medially and laterally from the distal and posterior condyles.(N.B. this may result in excessive valgus but this will be adjusted intra-operatively). Femoral flexion angle is then altered within the range of 0-7° to optimise the anterior cut exit point. If unable to accommodate size without notching anterior cortex or having the tip of the implant achieving bony contact size will be altered to achieve this. Medial lateral width of component will not overhang distal femur or will be downsized. 3. Tibial slope is then matched to native slope whilst not exceeding combined femoral flexion and tibial slope of more than 10°. If this value exceeds 10° then tibial slope is reduced. d. A standard anaesthetic approach involving Spinal anaesthetic involving 2.5mls of heavy bupivacaine and 30-60mcg buprenorphine(dependant on patient size and comorbidities). An Adductor block is then performed with ultrasound guidance using bupivacaine. Sedation or GA is then undertaken as per patient preference for comfort and anxiety. If the anaesthetic is required to be altered for any reason it will be done so at the discretion of the Consultant Anaesthetist in the best interests of the patient and any variation will be recorded. e. Surgical approach is consistent for both groups. Following Anaesthetic and IDC insertion a pre-prep is undertaken with alcohol based skin prep. A tourniquet is then applied and inflated to 300mm Hg immediately prior to skin preparation and draping. The surgical area is then protected with an iodine occlusive dressing (Ioban). f. The incision is midline with a medial parapatellar approach. Trackers and checkpoints are inserted into the femur and tibia, The ACL is resected if present. g. Registration is then undertaken. Osteophytes are then removed from distal femur and medial tibia. A pre-resection balancing workflow is then undertaken with maximal soft tissue gaps measured at 10 degrees of flexion and 90 degrees of flexion. h. The aim is to balance the knee within the alignment principles of each treatment arm such that extension is balanced from medial to lateral to within 1mm (2mm acceptable) and balanced from extension to flexion on the medial side to within 1mm (2 mm acceptable). The lateral flexion gap is allowed to be lax with the resections described above. The lateral flexion gap should not be tighter than the medial flexion gap. i. Once plan is balanced the TKA is executed utilising robotic arm assisted technique with soft tissue releases as required if balance not achieved within component positioning limits of each technique. j. The first 30 patients in each group that consent to the use of verasense pressure measures (adding 5 minutes to procedure time) will have intra-operative compartment pressures measured at 10, 45 and 90 degrees of flexion. j. The procedure is expected to be between 90 and 120 minute duration 5. Who Provided The surgeries will be performed by two orthopaedic surgeons familiar with the surgical techniques. Patient assessment will be performed by three orthopaedic trained physiotherapists. 6. How Patients suitable for knee arthroplasty will be identified by the consultant orthopaedic surgeons. If suitable, the research physiotherapists will contact the patients to inform them of the study. Patients will be emailed the consent form and PIF. Patients will then consult the research physiotherapist at their preoperative appointment, and be enrolled in the study if they wish. Interventions will be provided to one participant at a time as it is a surgical technique for the entire study cohort. Clinical testing will be provided face to face, one patient at a time. Patient reported outcome measures will be emailed to patients using the software, SOCRATES. Patients can fill their surveys out at home. If required they can also complete their surveys on available ipads in the consulting rooms. 7. Where All surgeries will be carried out at St. John of God Hospital, Subiaco. 8.When and how much The surgery will occur once. Patients will complete their PROMS and clinical testing outcomes at the pre-operatively, 6 week, 3month, 12 month and 2 year time points. 9.Tailoring Patients will be randomised to two groups, MA and FA.