1861: Dr. Fergusson performed resection arthroplasty of knee for arthritis. This was followed in 1863 by Dr. Verneil with interposition arthroplasty, which inserted foreign tissue (including capsule, skin, muscle, fat chromatized pig bladder) into the joint. This technique failed to provide lasting pain control.
1940s: Knee Hemiarthroplasty: Dr.Campbell was using a variation of the aforementioned technique (using free fascial graft), when he heard about Smith-Perterson’s success using mold arthroplasty for the hip. Campbell performed a mold hemiarthroplasty of the knee by fitting metallic molds to the femoral condyles. This technique failed to provide pain relief, however, the technique was modified by Smith-Peterson, who added a stem to the the prosthesis, and this allowed some very short-term success (called the Massachusetts General Hospital Femoral Condylar Replacement). During this same time period, Drs. McKeever & MacIntosh developed a tibial hemiarthroplasty, using vitallium (the same material being used for hip hemiarthroplasty at the time), which failed due to early loosening.
MacIntosh was also very important to the progress of TKA by developing many of the instruments necessary to reliably reproduce TKA. As you notice from this section, there is a huge emphasis on implant design, yet the bone cuts required for accurate and reproducible TKA is equally challenging as making good implants. He came up with the concept of creating flexion and extension gaps, and using spacers to measure and achieve ligament balance.
1950s: Walldius Shiers attempted the first bicompartmental knee arthroplasty (replacing both the femur & tibial articular surface) using a hinge with intramedullary stems. The initial design experienced a high loosening rate, and a follow up design called the GUEPAR hinge was developed, which shifted the axis of rotation posteriorly. This design still failed due to loosening as it failed to account for the complex rotational motion of the native knee.
1970s: The 1970s were a turning point for knee arthroplasty. The first designs that lay a foundation for current implants were developed and many of the current concepts and technologies that were developed in the 70s are used today. There were two design theories that took hold. One design attempted to recreate the normal knee anatomy and thus recreate normal knee kinematics. The other design attempted to simply the process by making anatomy secondary to function. This design emphasized knee mechanics over all else. Over the past 30 years, the second approach, this mechanics over anatomy, became the predominant method for designing TKA. However, with increasing technologic and technical sophistication, the first design, that of re-creating native anatomy and kinematics, as regain interest as a means to improve TKA function and patient satisfaction.
Important advances in material science proceeded this rapid development in TKA design. The original polyethylene (“high density plastic”) was developed in 1963. The bone cement methylmethacrylate was approved for medical devices by the FDA in 1971. Furthermore, advances in total hip arthroplasty, notably pioneered by Dr. John Charnley, occurred just prior to the 1970s, and many of the theories were applied to TKA.
1971: The first bicompartmental knee arthroplasty without a hinge for stabilization was the Polycentric Knee developed by Dr. Gunston, who had previously studied in Dr. John Charnley's lab. The design recognized that knee kinematics do not occur in a single plane like a hinge, rather the femoral condyles roll/glide with a changing center of rotation throughout the arc of motion. This was the first design that did not attempt to reconstruct the knee as a "hinge" but rather attempted to preserve knee anatomy (kept the cruciate and collateral ligaments). The procedure resurfaced the femoral condyles and cemented separate cobalt-chrome semicircular implants using polymethylmethacrylate (PMMA). On the tibial side, the medial and lateral tibial compartments were resurfaced and cemented in two concave polyethylene liners. This was an Anatomic Design. This design provided short-term pain relief, survivorship was significantly improved, however the implants failed due to inadequate fixation to the bone.
Other Anatomic design TKA were developed around the same time. The Kodama-Yamamoto knee was a metal femoral implant with a single polyethylene mold for the tibial side that was minimally constrained and had a central cutout for the cruciate ligaments. This implant was modified further as the Mark I and Mark I and demonstrated fairly good survivorship. Dr. Townley designed the Total Knee Original. The femoral implant had a decreasing radius of curvature to encourage femoral rollback, and a single polyethylene tibial implant. This model was the foundation for future anatomic designs such as the Cloutier, and Natural Knee.
Dr. Coventry, at the Mayo Clinic, developed the Geomedic knee in conjunction with Mr. Averill (engineer at Howmedica) . The Tibial component was solid polyethylene and conformed closely to the femoral component. It preserved the cruciate ligaments . However, due to the highly conforming articular geometry, in combination with cruciate preservation, there was a kinematic conflict that lead to early loosening. The implant was not a hinge, but the motion was too restricted. It was recognized that articular geometry and surrounding soft tissue both guide knee motion, yet, both cannot strongly guide motion otherwise there is conflict. While the design was generally considered a failure, derivations of its design were continued by Zimmer, and lead to successful implants such as the Miller-Gallante unicondylar knee, which is considered the first successful UKA. The Nextgen by Zimmer is also a variation of the Geomedic.
1970: Drs. Michael Freeman (surgeon) and SAV Swanson (Professor of Mechanical Engineering) developed the Freeman-Swanson bi-compartmental knee prosthesis, which is truly the first iteration (the fountainhead) of the current TKA, in both theory and design. In theory, the goal of the implant was to emphasize mechanical stability and prioritize function over preservation of anatomy. Dr. Freeman recognized that many of the knees requiring arthroplasty had significant angular deformity and therefore he decided that mechanical alignment was best achieved by sacrificing the cruciate ligaments. The implants were placed for mechanical alignment, not anatomic alignment.
Furthermore, without cruciate ligaments, the tibial eminence could be removed, offering multiple advantages. Instead of making many small bone cuts to reproduce the complex knee anatomy, simple parallel bone cuts could be made (one across the entire tibia) to facilitate the surgery and thus its reproducibility. Freeman introduced the idea of creating parallel cuts in the knee, perpendicular to the mechanical axis. He introduced intramedullary guides to achieve proper angulation of these cuts.
Freeman employed MacIntosh’s concept of spacer blocks for gap balancing. Laminar spreaders were first used for ligament balancing by Freeman after a visit from a South African doctor: Van Vuren. Freeman essentially standardized the basic steps for TKA (with one interesting difference. For the final implants he put the femur first, and then slid the tibial component into place like pushing a drawer back into a dresser).
The other advantage of removing the cruciates and the tibial eminence, was that a single cut across the tibia gives a larger bone surface area for the tibial implant, which then allows for a larger implant with better distribution of joint forces. However, Freeman later realized that removal of the tibial crest without replacing it with a tibia post, allowed for medial-lateral instability that caused implant failure.
Removing the cruciate ligaments also simplified the TKA kinematics. Implant stability and kinematics depended not on the surrounding soft tissue but rather through highly constraining articular geometry (concave tibial component). The femoral condyles were simplified to a single radius of curvature that matched the tibia. There was no posterior rollback, rather the kinematics were described as a “roller-in-trough” design.
The femoral component was made of cobalt-chrome. The tibial component was made of polyethylene. And there was just one implant size!
The patellofemoral joint was not addressed. The femoral component lacks an anterior flange.
1973: Freeman and Swanson produced the next generation of their implant by added the anterior flange to the femoral component and a patellar button to resurface the patella. This implant was named the ICLH (Imperial College London Hospital).
The next generation of design was the Freeman-Samuelson Knee which developed a tibial post to provide improved medial-lateral stability.
1971: At the same time that Dr. Freeman and associates were making great strides in the UK, a friend of his from medical school at Corpus Christie College in Cambridge UK, Dr. John Insall, was working with Dr. Chitranjan Ranawat and Dr. Peter Walker at HSS to develop a total condylar knee. Their first design was the Duocondylar Knee. In contrast to the Freeman-Swanson, the Duocondylar knee was based on recreating knee anatomy and native kinematics by preserving the cruciate ligaments. The tibial component was two flat pads (one for the medial and one for the lateral compartment) which did not attempt to control kinematics nor provide stability. This design relied on native soft tissue balance. Early results from this implant indicated that preservation of soft tissue (particularly the cruciate ligaments) impeded the correction of many deformed knees, and preservation of the tibial eminence prevented sturdy implantation of the components.
1974: These same designers (Insall et al) took the lessons from the Duocondylar implant and focused their efforts on the alternative theory of design: functional TKA (similar to the Freeman-Swanson). They then developed the Total Condylar (TC) prosthesis at HSS, which was strongly influenced by the ICLH design, and was truly the first TKA with reliable and reproducible functional outcomes and long-term survivorship. Similar to the ICLH, the cruciates were sacrificed, the femoral condyles were symmetric yet unlike the ICLH, there was a more anatomic change in the radius of curvature posteriorly (there were 2x radii, smaller poteriorly). There was an anterior flange with a trough to help with patellar tracking (there was a patellar button). The tibial component was polyethylene that was partially conforming (a “double-dish” shape, which was less conforming than the ICLH) and a lip anterior/posterior to prevent dislocation. The tibial component additionally had a very short post to replace the tibial eminence and give some medial-lateral stability. This was a Cruciate Sacrificing Design (cruciates removed, no post to replace).
This design was an improvement on the ICLH by utilizing both articular geometry and soft tissue tension to provide stability and kinematic guidance. The first implant was done at HSS by Dr. Insall.
It was completely congruent in extension and flexion. The main issue was that the significant conformity and congruency of the tibial design prevented any femoral rollback and thus limited knee flexion, and there were some cases of posterior subluxation in flexion.
1975: Total Condylar II. Despite using semicongruent articular geometry and a small tibial eminence, instability was still a problem with the TC design. During flexion, the femur could sublux anteriorly. To address this instability, the TC II created a central tibial post to engage the femur in flexion and prevent anterior subluxation (early version of the posterior stabilized design), yet the increased forces encountered through this post lead to higher loosening rates and this model was not continued for long,although it was the first foray into PS-design. Other variations of the TC design, led by Dr. Ranawat, include the Press-Fit Condylar (PFC) and PFC Sigma (DePuy).
1974: Dr. Eftekhar was the first to design the metal tibial baseplate with variable tibial polyethylene inserts. His design joined with the Mark I design (a derivation of the Kodama-Yamamoto knee). The initial tibial poly inserts came in sizes 6, 10, and 15.
1975: At the same time the New Jersey Knee was developed by Dr. Pappas and Buechel, which was the first implant with a mobile bearing and rotating platform, and was called the LCS (low contact stress).
1975: An HSS-trained surgeon, Dr. Merril Ritter was introduced to the TC prosthesis and requested a variation to the tibial component: cut out a posterior inlet to allow for preservation of the PCL. This was the origin of the CR-TKA.
1978: The Insall-Burstein prosthesis corrected the limitations of the Total Condylar Prosthesis by creating the first Posterior-Stabilized design: a central cam on the femur which engaged the back of tibial post at 70° of flexion and drove the contact point posteriorly during flexion to create femoral rollback. Most of the current PS designs derive from this Insall-Burstein knee. The major limitation of the IB knee was the high incidence of patellar dislocation. Since then, an asymmetric anterior flange was developed (higher laterally) to improve patellofemoral tracking.
REFERENCES
1. Gunston, F.H., Polycentric knee arthroplasty. Prosthetic simulation of normal knee movement: interim report. Clin Orthop Relat Res, 1973(94): p. 128-35.
2. Yamamoto, S., S. Nakata, and Y. Kondoh, A follow-up study of an uncemented knee replacement. The results of 312 knees using the Kodama-Yamamoto prosthesis. J Bone Joint Surg Br, 1989. 71(3): p. 505-8.
3. Goldberg, V.M. and B.T. Henderson, The Freeman-Swanson ICLH total knee arthroplasty. Complications and problems. J Bone Joint Surg Am, 1980. 62(8): p. 1338-44.
4. Insall, J., et al., Total condylar knee replacment: preliminary report. Clin Orthop Relat Res, 1976(120): p. 149-54.