There is no question that at some point many TKAs will be cementless-the question is when. The advantages of cementless TKA include a shorter operative time, no need for a tourniquet, more suitability for MIS, no concern for cement extrusion, and the history of THA. The concerns for cementless TKA include the history to date with cementless TKA (tibia and metal-backed patella), variable bony substrate, surgical cut precision, cost, revision concerns, and the patella (for patella component resurfacers).

Cemented total knee arthroplasty remains the gold standard and has proven to provide durable results in most patients. The early experience with cementless tibial fixation was problematic due to tibial micromotion leading to pain and loosening. Screw fixed tibial components had additional problems as portals for polyethylene debris leading to tibial osteolysis. Moreover, metal-backed patellar components were associated with a high failure rate and most surgeons began to cement all three components.

Renewed interest in cementless tibial fixation is driven in part by newer materials felt to be more suitable for ingrowth and by the perceived benefit of minimally invasive surgery. One of the concerns in limited exposure total knee arthroplasty is the difficulty in preventing the extravasation of cement posteriorly. If there is evidence-based data that quad sparing non-patella everting and limited incision length facilitates rehabilitation and does not jeopardise outcome, cementless tibial fixation will be a more attractive option in some patients. An additional concern is that the tibial surface is frequently quite variable in terms of the strength of the cancellous bone. Bone cement stabilises those differences and provides a homogeneous platform for load bearing through the tibial component.

Both gap balancing and measured resection for TKA will work and these techniques are often combined in TKA. The only difference is really the workflow. The essential difference in gap balancing is that you determine femoral component rotation by cutting the distal femur and the proximal tibia, and then using a spacer to determine femoral rotation.

I prefer measured resection because I am, for most cases, a cruciate retaining surgeon. It is not ideal to determine femoral rotation based upon a gap balancing if you retain the cruciate. It is also important to maintain the joint line, especially in cruciate retention, in order to reproduce more normal kinematics and balance the knee throughout the range of flexion and extension. It is my opinion that the soft tissue balancing is easier to do with measured resection and the workflow is easier.

The sequence of cuts and soft tissue balance is different if one is a gap balancing surgeon. This is more conducive for people who are cruciate substituters, but more difficult in a varus cruciate retaining knee. In that situation, if you determine femoral rotation by gap balancing with the tibia before you have cleared the posterior medial osteophytes in the varus knee, and remove the last bit of meniscus, you could artificially over rotate the femoral component causing posteromedial laxity. The major difference is that cutting the posterior cruciate will open the flexion space and allow the surgeon easier access to the posteromedial corner of the knee before the posterior femoral cut is made. It is also important to remember that in most cases cruciate substitution surgeons will make the flexion space 2 mm smaller than the extension space to compensate for the flexion space opening when the posterior cruciate is cut. The extensor mechanism plays an important role in flexion balance and should only be tested once the patella is prepared and the patella is back in the trochlear groove. I prefer gap balancing in most revision knees as I am virtually always substituting for the posterior cruciate in that case.

My technique for measured resection is to assess the character of the knee prior to surgery. Is it varus? Is it valgus? Does it hyperextend? Does it have a flexion contracture? Would the knee be considered tight or loose? I cut the distal femur first, based upon measured resection. I use anatomic landmarks to determine femoral rotation. My most consistent landmark is the transtrochlear line, which is not always from the top of the notch to the bottom of the trochlea. I will use the medial epicondyle and the posterior reference in a varus knee, but not in a valgus knee.

The tibial cut, also by measured resection, is easier once the femur has been prepared. The patellar cut is also a measured resection. Having done a preliminary soft tissue balance based upon the deformity, I will then use trial components to finish the soft tissue balance.

In summary, both techniques can be used successfully in a cruciate substituting knee, but measured resection, in my opinion, is preferable especially in varus arthritis when the posterior cruciate is retained

In 1983 we underscored the importance of understanding the cause or mechanism of failure following total knee arthroplasty. In this article we reported that revision total knee replacement was generally unsuccessful unless the surgeon new the mechanism of failure. In the ensuing years we have collectively made improvements in instrumentation, component design and material properties such that the mechanisms of failure are now different and less common than in the earlier years.

Early failure following total knee arthroplasty is generally related to technical issues. There are a myriad of such issues but many of them relate to component positioning and soft tissue balance. Post-operative wound complications are concerning as they cause an increased incidence of deep infection. Hematoma from over anticoagulation is a particular problem that leads to stiffness and increased risk for infection. Most knee systems now have multiple sizing options and instrument systems that can improve reproducibility of component implantation. Midterm failure is often due to flexion instability which has been reported in cruciate substitution and cruciate retention knees. The instability can be global, mid flexion, flexion or a combination of all 3. Issues with extension and mid flexion instability but no flexion instability are generally those with tight extensor mechanisms. Pain and stiffness are frequently due to component malalignment. One common problem is abnormal internal rotation of the tibial component.

Late failure in our institution is generally seen due to wear and loosening from earlier designs with inferior polyethylene. Late hematogenous infection occurs in people with immunocompromise, severe diabetes and diagnoses that alter the patient's ability to mount an immune response. The newest epidemic in total knee failure has been that of periprosthetic fracture. As these patients are becoming older and with worse proprioception, they are at greater risk. Generalised osteopenia and increased activity also increase the risk of fracture. Total knee arthroplasty represents a remarkable improvement in the care of the patient with knee arthritis. It is only by focusing upon and decreasing the causes of failure that we will advance use of this procedure in patient care.

This session will deal with common problems and challenges in knee arthroplasty surgery. It will include discussion of indications, surgical options, surgical technique, and management of complications.

This symposium is intended to focus on common problems that face all of us as orthopaedic surgeons rather than deal with issues that are almost never encountered. The panel includes a group of experienced surgeons who deal with such problems in their own practice.

Aging of Population – Baby Boomers, Millennials, Generation X

Burden of TJR in USA – Estimated ∼ 4 million US adults currently live with TKR (4.2% of the population aged 50 or older) – Females (4.8%); Males (3.4%)

Prevalence increased with increasing age

Estimated lifetime risk of primary TKR – 7.0% for males, 9.5% for females

Changes in Resident Education – Resident Work Hour Restrictions

Changes in Fellowship Education – Presumed shortage of fellowship trained arthroplasty surgeons, BWH Data

Changes in Healthcare Paradigm – Hospital – Margin/Mission, Efficiency, Contribution Margin, Ambulatory Centers

Academic/Community Practice – Revenue Driven, Diminished Education/Research Incentive

Arthroplasty Education – Time Restraints, Surgical Volume, Exposure to Options – CR/CS TKR, Revision TKR/THR, Femoral Cementing in THR

“Mind's EYE”

CME Training/Evidence-Based Medicine

Learn Basic Principles of Arthroplasty

“Be Neither the First nor Last to Embrace a New Technology”

“Always Act in the Best Interests of Your Patient”

It is important to remember that osteoarthritis is a noninflammatory condition that can affect 1, 2 or all 3 compartments of the knee. Moreover, this disease is a continuum from very mild to very severe involvement of the soft tissue, articular cartilage and bone. For this reason, a variety of nonsurgical and surgical options are indicated. The rheumatologist and/or orthopedist must understand the stage of the disease and fit that both to the pathology, age, activity level, and functional needs of the patient. For that reason, each of the options discussed today have an indication.

The important issue about tricompartmental replacement is that we have improved technology and technique and the indications of today are broader than those of 20 years ago. Hopefully, they will continue to evolve both in terms of materials and instruments. The American Rheumatologic Association (ARA) has stated that joint replacement has been the major improvement in the care of the arthritic patient. The tricompartmental solution is the treatment of choice in patients with inflammatory arthritis such as rheumatoid arthritis as well as the solution in osteoarthritic patients with tricompartmental disease. There is an indication for osteotomy, unicompartmental replacement and perhaps patellofemoral replacement. I think the next frontier will be to find disease modifying osteoarthritic drugs (DMOADS) that will provide disease intervention as the DMARDs have done in rheumatoid arthritis. Moreover, cartilage repair combined with osteotomy will hopefully allow us to prevent progression of this disease.

There is no question that excellent long-term results have been demonstrated with all-polyethylene tibial components. Moreover, improvements in polyethylene to increase wear resistance, maintain mechanical strength, and improve oxidative resistance lend even greater credence to the use of an all-polyethylene tibial component. There are several issues of concern. In revision knee replacement for reasons such as patellofemoral problems where the components are otherwise ideal, the arthrotomy performed during the revision usually creates a slight laxity requiring a thicker polyethylene or even a different tibial conformity. With an all-polyethylene tibia, this would require full component revision. It is also true that, even after careful trial reduction, the surgeon occasionally will find that the final construct is slightly lax requiring a thicker final insert. This again is difficult in the situation of all-polyethylene tibia. One of the advantages of an all-polyethylene tibia is to avoid back-sided wear that posed a substantial problem in the past. Most component systems have successfully dealt with a problem of back-sided wear making the advantage of a nonmodular all-polyethylene tibia moot. Finally, in a modular system, the surgeon has the advantage of cementing all components with the tibial trial and then having the ability to remove the trial component, clear the back of the knee and insert the final insert. Lowering health care costs is a laudable and necessary endeavor. We must choose TKR implants to fit patient demand and not overuse or underuse technology and know the true cost of the implants we use.

There is no question that excellent long-term results have been demonstrated with all-polyethylene tibial components. Moreover, improvements in polyethylene to increase wear resistance, maintain mechanical strength, and improve oxidative resistance lend even greater credence to the use of an all-polyethylene tibial component. There are several issues of concern. In revision knee replacement for reasons such as patellofemoral problems where the components are otherwise ideal, the arthrotomy performed during the revision usually creates a slight laxity requiring a thicker polyethylene or even a different tibial conformity. With an all-polyethylene tibia, this would require full component revision. It is also true that, even after careful trial reduction, the surgeon occasionally will find that the final construct is slightly lax requiring a thicker final insert. This again is difficult in the situation of all-polyethylene tibia. One of the advantages of an all-polyethylene tibia is to avoid back-side wear that posed a substantial problem in the past. Most component systems have successfully dealt with the problem of back-side wear making the advantage of a nonmodular all-polyethylene tibia moot. Finally, in a modular system, the surgeon has the advantage of cementing all components with the tibial trial and then having the ability to remove the trial component, clear the back of the knee and insert the final insert.

Cementless femoral fixation in total knee replacement has proven to be successful in many studies. There is a recent report by Berger et al, on failure of cementless fixation in a high flexion TKR design. This was with a FiberWire material that had good ingrowth characteristics but was not ideal in terms of immediate fixation.

Cementless patellar fixation to date has required a metal backed patella, which has proven to be problematic in most design. For this reason, most surgeons who resurface the patella do so with an all-polyethylene cemented design.

The major controversy is cemented tibial fixation. This is problematic when performed with ancillary screw fixation due to screw osteolysis. There are newer designs that have shown promise but cemented tibial fixation remains the gold standard.

It is true that early designs of cementless hips were associated with poor results, but newer designs have led to cementless fixation in total hip arthroplasty as the gold standard. It is clear that with newer materials, ancillary biologics and improved design that cementless total knee fixation will eventually prevail. At the present time, the wine needs to stay in the cellar for now.

To wake up in the morning facing a complex total hip revision can be unpleasant. Modern designs have greatly facilitated dealing with the most difficult revision situations both on the acetabular and femoral side. The surgeon faces blood loss, dislocation, infection, and a litany of other potential complications. Our advances in total hip revision have been outstanding but can pose very complex issues.

Total knee revision on the other hand is easier. The surgeon needs to ask a series of questions pre-operatively and intra-operatively. Pre-operatively, one must know the mechanism of failure. You also need to know “what is missing” in terms of skin, soft tissue, extensor mechanism, bone and ligaments.

Intra-operatively, the surgeon must know the difference between the flexion and extension gap, the position of the joint line, the extent of the bone loss and whether it is load bearing or non-load bearing, the ligamentous stability and the intramedullary shaft. Most modern knee revision designs allow the surgeon to create a paradigm to deal with all of these potential problems.

There, of course, are complex problems of malalignment, periprosthetic fracture and other deformities that add a level of complexity but most of these can be dealt with using standard revision designs without requiring custom prostheses.

The performance of ultra-high molecular weight polyethylene (UHMWPE) used in total joint replacement prosthesis depends on its wear resistance, oxidation resistance and mechanical properties. Several studies have now established that radiation crosslinking by applying a dose of 50–100 kGy gamma or electron beam radiation followed by remelting to quench free radicals fulfils the criterion of high wear resistance as well as oxidation resistance. However, post-irradiation remelting leads to a decrease in several mechanical properties of UHMWPE including fracture toughness and resistance to fatigue crack propagation, which are deemed important for components in joints where they are subjected to high stresses, such as in tibial components.

In this study, we used uniaxial compression and high-pressure crystallization to disentangle UHMWPE, expecting that this would assist in increasing its crystallinity since disentangled polymer chains would be more readily incorporated into crystalline lamellae, thereby increasing overall crystallinity. This could then result in an increase in some mechanical properties of irradiated, remelted UHMWPE since high crystallinity is associated with high modulus and yield stress. Uniaxial compression of irradiated, remelted GUR 1050 UHMWPE at 130C to a compression ratio up to 2.5 followed by remelting to recover crystallographic orientation showed no statistically significant increase in crystallinity (p> 0.05, ANOVA). High-pressure crystallization at 500 MPa and temperatures in a range of 130-220C also did not show statistically significant increase in crystallinity of irradiated, remelted UHMWPE. However high-pressure crystallization at 500MPa pressure and 240C, where crystallization occurs via the hexagonal phase, increased the crystallinity from 46.2% to 56.4% (p< 0.05, ANOVA).

We conclude that high-pressure crystallization via the hexagonal phase is more effective than uniaxial compression followed by strain recovery or high-pressure crystallization via the orthorhombic phase in increasing the crystallinity of irradiated, remelted UHMWPE, with potential to recover some mechanical properties.