The Napkin Sketch That Changed Knee Surgery
Discover how a late-night idea between a surgeon and an engineer evolved into the world's leading partial knee implant over the past 50 years
Great ideas often start in humble places. For the Oxford® Partial Knee, that place was a napkin, sketched upon late one night, by two visionaries: Mr. John Goodfellow, a surgeon, and Professor John O’Connor, an engineer at Oxford University.
Fifty years ago, knee replacement surgery looked very different. Traditional implants often struggled to replicate natural movement, placing stress on the components. In the 1970s, the major failure mechanism for knee replacements was the polyethylene wear caused by high stress through a patient’s range of motion.1
Goodfellow and O’Connor believed there was a better way. They shared a singular vision: to create a device that not only replaced the diseased bone but also restored the knee’s natural physiological movement. This approach reduced stress on the polyethylene bearing and aimed to extend the life of the joint replacement.2-3
Solving a Complex Problem
The pair realized that to mimic natural knee movement, the implant needed to move freely. Their goal was two-fold. First, they aimed to reduce the wear on the polyethylene (plastic) parts.2-3 Second, they wanted to preserve the patient’s healthy ligaments and remove only the diseased portion of the knee. By keeping the healthy parts of the knee intact, they could help the joint return to a more natural, pre-diseased state.4-6
This collaboration between engineering precision and surgical expertise resulted in the first fully congruous mobile bearing partial knee.7 Unlike fixed‑bearing implants, this design allowed plastic bearings to move freely between metal surfaces, significantly reducing wear.2-3
Initially, the team explored applying the concept to total knee replacements. However, after carefully analyzing patient results and clinical data, they discovered the design’s true strength lay in partial knee replacements - specifically for patients with arthritis on just the inner (medial) side of the knee.
Evolution Through the Decades
Over the last five decades the fundamental design features that made it revolutionary in the 1970s are still in use today because they work. Meanwhile, there have been refinements that have brought the implant to where it is today. Innovations such as the Microplasty® Instrumentation and reproducible technique expanded sizing options and cementless technology have helped deliver greater efficiency,8 reproducibility9 and continued global adoptions of the Oxford Partial Knee.
A Global Legacy
Today, the Oxford Partial Knee stands as a testament to that late-night collaboration decades ago. It has market approval in over 50 countries and is the most widely used partial knee implant in the world, accounting for over 50% of the global market share.10 It has maintained 94% survivorship in the UK Joint Registry for decades.11 Available in both cemented and cementless options, it also boasts one of the longest clinical histories of any orthopedic implant currently available.8,12-14
From a simple sketch to a global standard of care, the story of this implant reminds us that transformative, innovative ideas don’t always begin in operating rooms or laboratories. Sometimes, they start with two people, a shared conviction, and a napkin. Fifty years later, the idea on a late-night drawing continues to restore mobility, preserve natural movement and allow patients around the world to get back to activities they loved before knee pain.15
As we celebrate the 50 years of the Oxford Partial Knee, we’ll be sharing stories, breakthroughs and people who shaped its legacy. Stay with us and follow along on LinkedIn as we look back at five decades of innovation and forward to the future of knee restoration.
Important Safety Information
The Oxford Partial Knee is intended for use in individuals with osteoarthritis or avascular necrosis limited to the medial compartment of the knee and is intended to be implanted with bone cement. The Oxford Partial Knee is not indicated for use in the lateral compartment or for patients with ligament deficiency. Potential risks include, but are not limited to, loosening, dislocation, fracture, wear and infection, any of which can require additional surgery.
The Oxford Cementless Partial Knee System is indicated for use in unilateral knee procedures with osteoarthritis or avascular necrosis limited to the medial compartment of the knee. It is intended to be implanted without the application of bone cement for patients whose clinical condition would benefit from a shorter surgical time compared to the cemented implant. The Oxford Partial Knee is not indicated for use in the lateral compartment or for patients with ligament deficiency, or for use in simultaneous bilateral surgery or planned staged bilateral procedures. Potential risks include, but are not limited to, loosening, dislocation, fracture, wear and infection, any of which can require additional surgery. For a full list of product indications, contraindications and warnings, please see the associated product IFU.
References
1. Patel NG, et al. 50 years of total knee arthroplasty. Bone Joint 360. 2019;8(3):3-7. doi:10.1302/2048-0105.82.360688
2. Arthur LW, et al. Polyethylene bearing wear is comparable for cemented and cementless Oxford unicompartmental knee replacements: Ten-year results of a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2024 Feb;32(2):405-417. doi: 10.1002/ksa.12042. Epub 2024 Jan 31. PMID: 38298004.
3. Ghosh P, et al. Low polyethylene creep and wear following mobile-bearing unicompartmental knee replacement. Knee Surg Sports Traumatol Arthrosc. 2021 Oct;29(10):3433-3442. doi: 10.1007/s00167-020-06243-7. Epub 2020 Sep 17. PMID: 32940731; PMCID: PMC8458199.
4. Price AJ, et al. Simultaneous in vitro measurement of patellofemoral kinematics and forces following Oxford medial unicompartmental knee replacement. J Bone Joint Surg Br. 2006;88(12):1591-1595. doi:10.1302/0301-620X.88B12.18306
5.Mullaji AB, et al. Mobile-bearing medial unicompartmental knee arthroplasty restores limb alignment comparable to that of the unaffected contralateral limb. Acta Orthop. 2017;88(1):70-74. doi:10.1080/17453674.2016.1253327
6. National Joint Registry of England Wales, Northern Ireland, the Isle of Man and Guernsey. 21st Annual Report 2024
7. Capella M, et al. Mobile bearing and fixed bearing total knee arthroplasty. Ann Transl Med. 2016;4(7):127. doi:10.21037/atm.2015.12.64
8. Stempin R, et al. Midterm Results of Cementless and Cemented Unicondylar Knee Arthroplasty with Mobile Meniscal Bearing: A Prospective Cohort Study. Open Orthop J. 2017 Oct 31;11:1173-1178. doi: 10.2174/1874325001711011173. PMID: 29290853; PMCID: PMC5721307
9.Alvand A, et al. New instrumentation system for cementless mobile-bearing unicompartmental knee arthroplasty improves surgical performance particularly for trainees. Knee. 2021;31:46-53. doi:10.1016/j.knee.2021.05.001
10.Internal Summary_202100608_GLBLPKRMRKT
11. National Joint Registry of England Wales, Northern Ireland, the Isle of Man and Guernsey. 21st Annual Report 2024
12. Jackson WF, et al. 40 years of the Oxford Knee. Bone Joint J. 2016;98-B(10 Supple B):1-2. doi:10.1302/0301-620X.98B10.38076
13. Price AJ, Svard U. A second decade lifetable survival analysis of the Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res. 2011;469(1):174-179. doi:10.1007/s11999-010-1506-2
14.Mohammad, H. R., et al. (2018). Long-term outcomes of over 8,000 medial Oxford Phase 3 Unicompartmental Knees—a systematic review. Acta Orthopaedica, 89(1), 101–107. https://doi.org/10.1080/17453674.2017.1367577
15. Walton, NP. Patient-Perceived Outcomes and Return to Sport and Work: TKA Versus Mini-Incision Unicompartmental Knee Arthroplasty. J Knee Surg. 2006;19:112-116.
