Total knee replacement Genesis 2 (PS) with bi-convex patella (Smith and Nephew) surgical technique
Subscribe to get full access to this operation and the extensive Knee Surgery Atlas.
Learn the Total knee replacement Genesis 2 (PS) with bi-convex patella (Smith and Nephew) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Total knee replacement Genesis 2 (PS) with bi-convex patella (Smith and Nephew) surgical procedure.
The Genesis II knee replacement is a popular bicondylar TKR design which has a proven track record. Dating from the mid 1990s, the Gen II was designed by James Rand, Bob Bourne and Richard Laskin, to incorporate a number of specific design features to optimise performance.
The key benefits of the Genesis II are:
- Asymmetric posterior femoral condyles – the medial posterior condyle was reduced from 9.5mm to 7mm thick to create an ‘external rotation’ of the femoral component relative to the tibia, without changing the trochlea position by physically rotating the component externally relative to the femoral bone. This improves femorotibial contact geometry throughout range as well as optimising patella tracking.
- The coronal geometry is rounded at its edges to improve femoro-tibial contact further and also reducing edge loading which subsequently reduces wear.
- The trochlea groove is sigmoid shaped to allow the patella to be ‘met’ by the femoral component laterally and as the patella medialises on its journey to the tibial tubercle, it is supported underneath by the trochlea of the femoral component.
- The tibial baseplate is asymmetric to optimise tibial coverage for improved sizing and fixation, thus allowing transfer of load through the whole tibial plateau.
- The tibial stem is offset medially from the centre of the tibial component to mirror the native anatomic metaphyseal – diaphyseal mismatch of most patients, which on average is 3mm.
- The Genesis II system was introduced with Cruciate retaining, quickly adding posterior stabilised and there are both uncemented and cemented options
- The Genesis II is available with Cobalt Chrome or Oxinium Femoral components; the Oxinium bearing surface has been shown to reduce where rates in vitro and be clinically safe at 10 years in patients.
- Polyethylene tibial liners are available in standard or highly crosslinked forms (Ultra High Molecular Weight Polyethylene), although the high flexion liner is only available in UHMWPE.
In terms of which variant of Genesis II to choose, I have settled on cemented fixed bearing posterior stabilised with cobalt chrome femoral components for ‘standard’ TKRs. I will always try and perform a partial knee replacement if possible, but once I have made the decision that the whole joint is involved I chose to resurface the patella in all patients. For this I choose the biconvex inset Genesis patella as this allows careful fine tuning of patella construct thickness as described in this operation technique and also the Orthoracle technique Smith and Nephew Journey patello-femoral replacement .
The Biconvex Inset Patella has a 2.3% revision rate at 10 years according to Erak et al; they found that in a series of 521 inset patellae, in 431 patients, there were 14 revisions at 10 years which equates to a 2.7% revision rate. However in the same study at 10 years post implantation, in non-revised patients, there was only a 7.8% incidence of anterior knee pain which is a very low level.
In younger higher demand patients I use the Oxinium femoral component with UMWPE High Flex polyethylene liners; the age bracket for change is around 60-65 years of age in my opinion but this is more dependant on biological age, weight and function of the patient.
Author: James Murray FRCS
Institution: The Avon Orthopaedic Centre, Southmead Hospital, Bristol, UK
- Each operation and the questions associated become a named course in the CPD section
- The operative technique itself is read as a lesson as is any company implant information if this is being assessed.
- You’ll need to tick the box to confirm this has been done and can do this immediately if you have already read the op tech.
- The vast majority of operations have a 10-15 MCQ quiz covering all aspects of the decision making and the technique
- There are four possible answers of which one is correct (or on occasion more correct) than the others.
- There are additional quiz modules on the surgical steps, the implants and problem cases being added continually
- The course is completed once all the lessons are read and quizzes submitted and passed.
- On successful completion of each quiz you will receive validated CPD points that add to the certificate in your CPD folder.
- Your dashboard also will contain a record of the time you have spent logged onto and using the site.
- The timer suspends after 5 minutes though if there is no activity.
- When you restart you will resume at the same point in the module.
- Once you have completed each quiz you will need to feedback on the module first then click “submit” and your paper will be marked.
The pass mark is 75%.
- If you fall below this level you will be directed back to re-read the slides where you’ve tripped up.
- Once these have been read you can re-do just the questions you failed on.
- Once you have passed the quiz you can return at a future stage & resit .
- Operation Quiz – 1 CPD point
- Surgical steps Quiz – 1/4 CPD point
- Implants Quiz – 1/4 CPD point
- Problem case Quiz – 1/2 CPD point
One CPD point equates to one hour of academic activity
Welcome to the Professional Development question section. The objective of taking these tests is to demonstrate that you have understood all aspects of the assessment and management of patients requiring surgical intevention. On successful completion you will receive a certificate accredited by both the Royal College of Surgeons of both England and Edinburgh as well as the British Orthopaedic Association.
Our content is designed for both Surgeons in independent practice and Surgeons in training.