The entirety of the patient experience after contemporary total knee and total hip replacements in 2017 is markedly different from that encountered by patients just a decade ago. Ten years ago most patients were treated in a traditional sick-patient model of care and because they were assumed to require substantial hospital intervention, many cumbersome and costly interventions (e.g. indwelling urinary catheters, patient-controlled-analgesic pumps, autologous blood transfusion, continuous passive motion machines) were a routine part of the early post-operative experience. Today the paradigm has shifted to a well-patient model with a working assumption that once a patient has been medically optimised for surgery then the intervention itself, hip or knee replacement, will not typically create a sick-patient. Instead it is expected that most patients can be treated safely and more effectively with less intensive hospital intervention. While as orthopaedic surgeons we are enamored with the latest surgical techniques or interesting technologies most busy surgeons recognise that advances in peri-operative pain management, blood management, and early-mobilization therapy protocols account for the greatest share of improvements in patient experience over the past decade.

One can think pragmatically to get ahead and stay ahead of 3 predictable physiologic disturbances that adversely impact rapid recovery after knee and hip replacement: fluid/blood loss; pain; and nausea. The modern orthopaedic surgeon and his/her care team needs a simple strategy to pro-actively, not reflexively, manage each of those 3 predictable impediments to early recovery. Those surgical teams that routinely get ahead and stay ahead in each of those areas will routinely witness faster recovery, lower costs and greater patient satisfaction and that is clearly a win for patient and surgeon alike.

Effective pain management improves patient satisfaction, decreases hospital stay, and facilitates discharge to home. Today's emphasis is on a multi-modal strategy that minimises the use of opioids. Most protocols use pre-operative medications including an NSAID, acetaminophen, an oral opioid and some include gabapentin. Regional anesthesia is typically preferred over general. Both peripheral nerve blocks and periarticular local anesthetic cocktail injections have proved as effective adjuncts in decreasing early post-operative pain. Post-operative oral medications delivered on a schedule, not just as needed, often include acetaminophen, an NSAID and some include gabapentin. Oral and parenteral opioids are reserved for breakthrough pain.

Deep peri-prosthetic infection after partial or total knee arthroplasty is a disconcerting problem for patient and surgeon alike. The diagnosis of infection is sometimes obvious but frequently requires that the surgeon maintain a substantial index of suspicion for infection as the cause of pain or poor outcome after any joint arthroplasty. While surgical debridement with component retention is appropriate in a subgroup of patients with an acute peri-prosthetic infection, most delayed and chronic infections are best treated with component resection. With carefully selected patients and very aggressive debridement protocols some success has been demonstrated in Europe with single-stage exchange for infection. Most surgeons in North America, however, are unfamiliar with the very aggressive debridement techniques employed at European centers that promote single stage replant; and few surgeons in North America are currently comfortable in cementing a hinged total knee replacement in place for the typical infected TKA nor do they have the patience to re-prep and drape with an entirely new OR setup after debridement and prior to the insertion of the new implant − 2 steps that are often mentioned as important to the success of single stage exchange.

The pre-eminent role of two-stage exchange as the definitive treatment was established over 30 years ago. Two-stage exchange remains the gold-standard in treatment with an established track record from multiple centers and with multiple different types of infecting organisms. Some of the historical problems with two-stage exchange, such as limited mobility during the interval stage, have been mitigated with the development of effective articulating spacer techniques. Further, the emergence of drug resistant bacteria and the possibility of fungal infection make two-stage exchange the best choice for the majority of patients with deep periprosthetic joint infection in 2017.

Tranexamic acid (TXA) is an effective medication to limit blood loss and transfusion requirements in association with contemporary total joint arthroplasty. TXA is in a class of medications termed anti-fibrinolytics due to their action to limit the breakdown of clot that has already been formed. It is useful to note that TXA does not promote the formation of clot, it simply limits the breakdown of already established clot. A recent systematic review and meta-analysis of randomised clinical trials of TXA use in total hip replacement demonstrated: 1) a substantial reduction in the proportion of patients who required transfusion and 2) no increase in DVT or PE. Similarly a recent Cochrane Database systematic review assessed Anti-fibrinolytic Use for Minimizing Perioperative Blood Transfusion and found tranexamic acid to be effective in reducing blood loss during and after surgery and to be free of serious adverse effects. In orthopaedic surgery varying doses have been used over time. A pragmatic dosing approach for Total Knee and Total Hip patients has been used at the Mayo Clinic over the past 16 years: 1 gram IV over 10 minutes prior to incision (delivered at same time as pre-op antibiotics) followed by 1 gram IV over 10 minutes at the time wound closure is initiated. Infusion rates greater than 100 mg/minute have been associated with hypotension and thus the recommendation for 1 gram over 10 minutes. A recent review of 1500 TKA patients at Mayo Clinic revealed a very low prevalence of clinically symptomatic DVT and PE when tranexamic acid was used with 3 different thromboembolic prophylaxis regimens (aspirin and foot pumps; coumadin; low molecular weight heparin). The safety of TXA for patients with coronary stents has not been fully clarified.

115 patients undergoing primary unilateral THA were randomized to either DAA or MPA. Groups did not differ in mean age, sex, or mean body mass index. Functional results included time to discontinue gait aids, discontinue all narcotics, and independence with various activities of daily living. Activity in study subjects was measured with 5 wearable activity monitoring sensors with tri-axial MEMS accelerometers and validated custom algorithms and conducted over three days at pre-op, 2 weeks, 8 weeks, and one year. SF-12, WOMAC, and HHS scores to one year were also tabulated.

Early functional recovery slightly favoured DAA compared to MPA; time to discontinue walker (10 vs. 14.5 days), time to discontinue all gait aids (17.3 vs 23.6 days), ascend stairs with gait aid (5.4 vs. 10.3 days), and to walk 6 blocks (20.5 vs. 26.0 days). There were no other differences in early functional milestones. Activity monitoring at two weeks postoperatively slightly favoured DAA; mean steps per day were 3897 versus MPA 2,235, percent of day active, DAA 10.5% versus MPA 6.9%. There was no difference in activity monitoring pre-operatively, at two months, or at one year. There was no difference at one year with the SF-12. There was no difference in the SF-12 mental component or the HOOS at any time point. There was no loosening or subsidence of any of the components in any hip.

Both the direct anterior and posterior approach provided excellent early postoperative recovery with a low complication rate. The direct anterior patients had slightly faster recovery than the mini-posterior approach patients, with slightly shorter times to achieve milestones of function and as measured by advanced, quantitative activity monitoring at 2 weeks postoperatively.

Background

Total knee arthroplasty (TKA) overall is a very reliable, durable procedure. Biomechanical studies have suggested superior stress distribution in metal-backed tibial trays, however, these results have not been universally observed clinically. Currently, there is a paucity of information examining the survival and outcomes of all-polyethylene tibial components.

The entirety of the patient experience after contemporary total knee and total hip replacements in 2016 is markedly different from that encountered by patients just a decade ago. Ten years ago most patients were treated in a traditional sick-patient model of care and because they were assumed to require substantial hospital intervention, many cumbersome and costly interventions (e.g. indwelling urinary catheters, patient-controlled-analgesic pumps, autologous blood transfusion, continuous passive motion machines) were a routine part of the early post-operative experience. Today the paradigm has shifted to a well-patient model with a working assumption that once a patient has been medically optimised for surgery then the intervention itself, hip or knee replacement, will not typically create a sick-patient. Instead it is expected that most patients can be treated safely and more effectively with less intensive hospital intervention. While as orthopaedic surgeons we are enamored with the latest surgical techniques or interesting technologies most busy surgeons recognise that advances in peri-operative pain management, blood management, and early-mobilisation therapy protocols account for the greatest share of improvements in patient experience over the past decade.

One can think pragmatically to get ahead and stay ahead of 3 predictable physiologic disturbances that adversely impact rapid recovery after knee and hip replacement: fluid/blood loss; pain; and nausea. The modern orthopaedic surgeon and his/her care team needs a simple strategy to pro-actively, not reflexively, manage each of those 3 predictable impediments to early recovery. Those surgical teams that routinely get ahead and stay ahead in each of those areas will routinely witness faster recovery, lower costs and greater patient satisfaction and that is clearly a win for patient and surgeon alike.

Effective pain management improves patient satisfaction, decreases hospital stay, and facilitates discharge to home. Today's emphasis is on a multi-modal strategy that minimises the use of opioids. Most protocols use pre-operative medications including an NSAID, acetaminophen, an oral opioid and some include gabapentin. Regional anesthesia is typically preferred over general. Both peripheral nerve blocks and periarticular local anesthetic cocktail injections have proved as effective adjuncts in decreasing early post-operative pain. Post-operative oral medications delivered on a schedule, not just as needed, often include acetaminophen, an NSAID and some included gabapentin. Oral and parenteral opioids are reserved for breakthrough pain.

Prevalence

Periprosthetic fractures around a total knee are uncommon but not rare; various large database studies suggest 0.3–2.5%. Patients at highest risk are typically older patients and those with poor quality bone from various etiologies. Supracondylar femur fractures are often associated with a high stress zone at the metaphysis/diaphysis junction near the superior edge of femoral component.

Multiple contemporary TKA designs that sacrifice the anterior cruciate ligament and then either retain or substitute for the posterior cruciate ligament have demonstrated-records of good durability and good function across joint registries worldwide. In recent years there has been an emphasis on improving function in TKA and to that end various strategies including changes in surgical alignment targets (kinematic alignment), the addition of advanced technologies such as computer navigation and sensors in trial components, the expansion of indications for unicompartmental knee arthroplasty and the re-introduction of total knee implants that preserve both the ACL and PCL have been championed. Early ACL/PCL retaining total knee implants had mixed results with some designs failing while others championed by Cloutier and by Pritchett have had some success in regard to reasonable durability. Unfortunately those early designs, despite decent durability, did not conclusively demonstrate better function.

More recently a new bi-cruciate retaining TKA was introduced with some substantial fanfare. Unfortunately, the widely touted theoretical or potential benefits of bi-cruciate preservation (in regard to better function) have failed to materialise or have been offset by a higher than expected re-operation rate. Even some of the initial proponents of the bi-cruciate implants have noted that the short-term findings are not very encouraging. The largest report to date shows 5% vs. 1.6% all-cause revision at 1 year (BCR vs. CR, respectively) and no improvement in standardised patient reported outcome measures. Some have placed their hopes for BCR TKA on the introduction of robotic technologies or advanced sensor devices but whether those prove to be meaningful enabling technologies remains to be determined. In 2017 it appears that while bi-cruciate retaining TKA is intellectually intriguing it does require the practicing surgeon to cross “a bridge too far.”

The biomechanical rationale for osteotomy and the pathogenesis of degenerative arthrosis accompanying malalignment has been delineated well. Malalignment of the limb results in added stress on damaged articular cartilage and causes further loss of articular cartilage that subsequently exacerbates the limb malalignment. A downward spiral of progressive deformity and additional loss of articular cartilage occurs over time. Osteotomy can be used to realign the limb, reduce stress on the articular cartilage at risk and share the load with the opposite compartment of the knee. In appropriately selected patients osteotomy is a reliable operation to improve pain and function. Over the past two decades osteotomy has been viewed largely as a temporizing measure to buy time for patients before they ultimately have a total knee arthroplasty. In this role, osteotomy has largely been accepted as successful. Substantial improvements in pain and function have been documented and seem to hold up well over a 7- to 10-year period after the osteotomy. Medial opening wedge osteotomy has recently gained in popularity in the United States after a long period of use in Europe. Potential advantages of the medial opening wedge technique include the ability to easily adjust the degree of correction intra-operatively, the ability to correct deformities in the sagittal plane as well as the coronal plane, the need to make only one bone cut, and avoiding the tibiofibular joint. The downsides of the opening wedge technique include the need for bone graft to fill the created defect, a potentially higher rate of non-union or delayed union, and a longer period of restricted weight bearing after the procedure.

Intraoperative fractures during primary total hip arthroplasty (THA) can occur on either the acetabular or the femoral side. A range of risk factors including smaller incision surgery, uncemented components, prior surgery, female sex, osteoporosis, and inflammatory arthritis have been identified. Acetabular fractures are rare but when they do occur often are underrecognised. It is not uncommon for intraoperative acetabular fractures to be discovered only postoperatively. Intraoperative acetabular fractures are associated with cementless implants and a number of identified anatomic risk factors. Factors related to surgical technique, including excessive under-reaming, excessive medialization with aggressive reaming, and implant designs such as an elliptical cup design are associated with higher risk. Treatment of acetabular fractures is dependent on whether they are diagnosed intraoperatively or postoperatively. When discovered intraoperatively, supplemental fixation should be added in the form of additional screw fixation, placing a pelvic plate, or using an acetabular reconstruction cage and morselised allografts. Acetabular reamings, obtained during preparation of the acetabulum, can be used for local bone graft. The goal should be stability of both the fracture and acetabular cup. Postoperatively, weight bearing and mobilization protocols may require modification, with many surgeons choosing a period of toe-touch weight-bearing in such cases. Acetabular fractures found postoperatively require the surgeon to make a judgement on the relative stability of the implant and the fracture to determine if immediate revision surgery or protected weight-bearing alone is appropriate.

On the femoral side intraoperative fractures can occur around the greater trochanter, the calcar, or in the diaphysis. Fractures of the greater trochanter are problematic because of their tendency to displace due to the attachment of the abductors and the strong force they apply. Tension band wiring techniques will work for many greater trochanteric fractures while a trochanteric plate may be occasionally called for. With either form of fixation strong consideration should be given to 6–8 weeks of protected weight bearing postoperatively. Short longitudinal cracks in the medial calcar region are not rare with uncemented implants. Calcar fractures that do not extend below the lesser trochanter can often be managed with a single cerclage cable. Calcar fractures extending below the lesser trochanter should be scrutinised with additional intraoperative xrays; longer longitudinal cracks can be managed with 2 cables while more complex fractures that exit the diaphysis demand a change to a distally fixed implant and formal fracture reduction. Distal diaphyseal fractures are relatively uncommon in the primary setting, but not rare in the revision setting. When recognised intraoperatively, distal diaphyseal fractures can be treated effectively with cerclage cables. Distal diaphyseal longitudinal cracks noted postoperatively do not typically mandate a return to the OR and instead can be managed with 8 weeks of protected weight bearing.

The biomechanical rationale for osteotomy and the pathogenesis of degenerative arthrosis accompanying malalignment has been delineated well. Malalignment of the limb results in added stress on damaged articular cartilage and causes further loss of articular cartilage that subsequently exacerbates the limb malalignment. A downward spiral of progressive deformity and additional loss of articular cartilage occurs over time. Osteotomy can be used to realign the limb, reduce stress on the articular cartilage at risk and share the load with the opposite compartment of the knee. In appropriately selected patients osteotomy is a reliable operation to improve pain and function. Over the past two decades osteotomy has been viewed largely as a temporizing measure to buy time for patients before they ultimately have a total knee arthroplasty. In this role, osteotomy has largely been accepted as successful. Substantial improvements in pain and function have been documented and seem to hold up well over a 7 to 10 year period after the osteotomy. Medial opening wedge osteotomy has recently gained in popularity in the United States after a long period of use in Europe. Potential advantages of the medial opening wedge technique include the ability to easily adjust the degree of correction intraoperatively, the ability to correct deformities in the sagittal plane as well as the coronal plane, the need to make only one bone cut, and avoiding the tibiofibular joint. The downsides of the opening wedge technique include the need for bone graft to fill the created defect, a potentially higher rate of non-union or delayed union, and a longer period of restricted weight bearing after the procedure.

Surgeons have widely disparate views on how to improve outcomes for patients following total knee arthroplasty. Over the past decade we have witnessed a remarkable transformation of the entire process of care surrounding total knee arthroplasty. The entirety of the patient experience after contemporary total knee replacement in 2015 is markedly different from that encountered by patients just a decade ago. Ten years ago most patients were treated in a traditional sick-patient model of care and because they were assumed to require substantial hospital intervention, many cumbersome and costly interventions (e.g. indwelling urinary catheters, patient-controlled-analgesic pumps, autologous blood transfusion, continuous passive motion machines) were a routine part of the early postoperative experience. Today the paradigm has shifted to a well-patient model with a working assumption that once a patient has been medically optimised for surgery then the intervention itself, knee replacement, will not typically create a sick-patient. Instead it is expected that most patients can be treated safely and more effectively with less intensive hospital intervention. While as orthopaedic surgeons we are enamored with the latest surgical techniques or interesting technologies most busy surgeons recognise that advances in perioperative pain management, blood management, and early-mobilization therapy protocols account for the greatest share of improvements in patient experience over the past decade.

With that paradigm shift in the hospital/surgical part of the total knee experience comes renewed interest and emphasis on function after TKA. Most surgeons are well aware of a “satisfaction gap” between the results of total hip replacement and total knee replacement. While studies report varying percentages (based on the definition of satisfaction and particular patient populations) what is clear is that 10–20% of patients are not fully satisfied after knee replacement. Researchers have highlighted some of this discordance with the introduction of the Forgotten Joint Score. These researchers and others can consistently point to higher satisfaction or fewer residual symptoms in patients who have undergone hip arthroplasty versus knee arthroplasty. What is also interesting to note, however, is that even amongst otherwise healthy control patients there are more baseline symptoms referable to the knee than to the hip. This may indicate that with knee arthroplasty we are chasing a more elusive target than is the case in hip arthroplasty.

Most surgeons today would agree that alignment plays an important role in TKA function and survival, but certainly factors other than alignment are also important in determining the survival of modern total knee replacements. The evidence suggests that ideal alignment after knee replacement is probably very specific for any given patient and influenced by individual differences. There is a complex interplay between limb alignment, component rotation, sizing, ligament balance, and gait dynamics. Moving forward, more attention needs to be devoted to function in knee replacement in order to improve patient satisfaction. While the mechanical axis has been useful, future improvements are dependent on hitting better targets. The historic focus on radiographic outliers to explain total knee failures has been incomplete at best and has possibly dulled and constrained our collective intellectual curiosity.

For 3 decades surgeons have vigorously debated whether it is reasonable to offer simultaneous bilateral total knee replacement (TKA) to patients. Even after this substantial period of time there remain no randomised clinical trials that have addressed this issue and thus, it remains difficult to fully evaluate both the relative risks and the absolute risks of bilateral simultaneous versus staged bilateral knee replacement. What has emerged over the past couple of decades, however, is an understanding that there is a subset of patients with substantial comorbidities such as pre-existent cardiac disease and advanced age for whom bilateral simultaneous knee replacement seems unwise. For younger or otherwise healthy patients the debate continues in 2016 and seems to be focused less on the data itself than on how individual surgeons come to reconcile the differences between Relative Risk and Absolute Risk. When data is pooled from multiple retrospective studies of simultaneous versus staged bilateral TKA there are 2 clear trends that appear in the data. First, the relative risk of certain substantial complications (cardiac, thromboembolic, neurologic, gastrointestinal, and death) seems to be higher after simultaneous bilateral TKA than after staged bilateral TKA. Oakes and Hanssen highlighted these differences in Relative Risk noting that for each of those 5 outcomes there was a 2 to 5 times greater incidence of these complications after bilateral versus unilateral TKA. At the same time, however, it is clear that for most medically uncomplicated patients the Absolute Risk of a major complication is still fairly low — it is likely that >93% of such patients can undergo simultaneous bilateral TKA without encountering a major complication. Individual surgeons and individual patients often view those kinds of statistics in markedly disparate ways. One set of surgeons and patients will view the Relative Risk as most important and be decidedly concerned about the 2–5 times higher risk of certain complications. Another set of patients and surgeons will look at the Absolute Risk as most important and determine that it is decidedly most likely (>93%) that an individual healthy patient will make it through bilateral simultaneous TKA without major medical complications. Overall the conclusions of Oakes and Hanssen from a decade ago remain relevant in 2016: the overall risk of a peri-operative complication is higher with simultaneous bilateral TKA … and this is particularly true for the risk of peri-operative death. While some surgeons and some patients will decide that the increases in Relative Risk is offset by the fairly low Absolute Risk of complications and thus, feel comfortable with bilateral simultaneous TKA, other patients and other surgeons will not.

Tranexamic acid (TXA) is an effective medication to limit blood loss and transfusion requirements in association with contemporary total joint arthroplasty. TXA is in a class of medications termed anti-fibrinolytics due to their action to limit the breakdown of a clot that has already been formed. It is useful to note that TXA does not promote the formation of a clot, it simply limits the breakdown of already established clots. A recent systematic review and meta-analysis of randomised clinical trials of TXA use in total hip replacement demonstrated: 1) a substantial reduction in the proportion of patients who required transfusion and 2) no increase in DVT or PE. Similarly a recent Cochrane Database systematic review assessed Anti-fibrinolytic Use for Minimizing Perioperative Blood Transfusion and found tranexamic acid to be effective in reducing blood loss during and after surgery and to be free of serious adverse effects. In orthopaedic surgery, varying doses have been used over time. A pragmatic dosing approach for Total Knee and Total Hip patients has been used at the Mayo Clinic over the past 16 years: 1 gram IV over 10 minutes prior to incision (delivered at same time as pre-operative antibiotics) followed by 1 gram IV over 10 minutes at the time wound closure is initiated. Infusion rates greater than 100 mg/minute have been associated with hypotension and thus the recommendation for 1 gram over 10 minutes. A recent review of 1500 TKA patients at Mayo Clinic revealed a very low prevalence of clinically symptomatic DVT and PE when tranexamic acid was used with 3 different thromboembolic prophylaxis regimens (aspirin and foot pumps; coumadin; low molecular weight heparin). The safety of TXA for patients with coronary stents has not been fully clarified.

The entirety of the patient experience after contemporary total knee and total hip replacements in 2016 is markedly different from that encountered by patients just a decade ago. Ten years ago most patients were treated in a traditional sick-patient model of care and because they were assumed to require substantial hospital intervention, many cumbersome and costly interventions (e.g. indwelling urinary catheters, patient-controlled-analgesic pumps, autologous blood transfusion, continuous passive motion machines) were a routine part of the early post-operative experience. Today the paradigm has shifted to a well-patient model with a working assumption that once a patient has been medically optimised for surgery then the intervention itself, hip or knee replacement, will not typically create a sick-patient. Instead it is expected that most patients can be treated safely and more effectively with less intensive hospital intervention. While as orthopaedic surgeons we are enamored with the latest surgical techniques or interesting technologies most busy surgeons recognise that advances in peri-operative pain management, blood management, and early-mobilization therapy protocols account for the greatest share of improvements in patient experience over the past decade.

One can think pragmatically to get ahead and stay ahead of 3 predictable physiologic disturbances that adversely impact rapid recovery after knee and hip replacement: fluid/blood loss; pain; and nausea. The modern orthopaedic surgeon and his/her care team needs a simple strategy to proactively, not reflexively, manage each of those 3 predictable impediments to early recovery. Those surgical teams that routinely get ahead and stay ahead in each of those areas will routinely witness faster recovery, lower costs and greater patient satisfaction and that is clearly a win for patient and surgeon alike.

Effective pain management improves patient satisfaction, decreases hospital stay, and facilitates discharge to home. Today's emphasis is on a multi-modal strategy that minimises the use of opioids. Most protocols use pre-operative medications including an NSAID, acetaminophen, an oral opioid and some include gabapentin. Regional anaesthesia is typically preferred over general. Both peripheral nerve blocks and periarticular local anesthetic cocktail injections have proved as effective adjuncts in decreasing early post-operative pain. Post-operative oral medications delivered on a schedule, not just as needed, often include acetaminophen, an NSAID and some included gabapentin. Oral and parenteral opioids are reserved for breakthrough pain.

There has been a recent increase in interest for non-cemented fixation in total knee arthroplasty (TKA), however, the superiority of cement fixation is an ongoing debate. Whereas the results based on Level III and IV evidence show similar survivorship rates between the two types of fixation, Level I and II evidence strongly support cemented fixation. United Kingdom, Australia, Sweden, and New Zealand registry data show lower failure rates and greater usage of cemented than non-cemented fixation. Case series studies have also indicated greater functional outcomes and lower revision rates among cemented TKAs. Non-cemented fixation involves more patellofemoral complications, including increased susceptibility to wear due to a thinner polyethylene bearing on the cementless metal-backed component. The combination of results from registry data, prospective randomised studies, and meta-analyses support the current superiority of cemented fixation in TKAs.

Cement Technique: 1. Proper exposure with adequate length of incision; 2. Pulsatile lavage to the cut to clean the cancellous bone; 3. Drill holes in the sclerotic bone surfaces; 4. Heated Simplex cement at a doughy state; 5. Apply cement on the cut bony surfaces including the posterior femoral condyles and pressurised, apply cement on the components as well and; 6. Further pressurization in extension with trial insert.

Contemporary techniques to perform total knee arthroplasty use either conventional instrumentation with intramedullary and extramedullary referencing or use a computer navigation system that requires insertion of femoral and tibial tracking pins and an intra-operative registration process. Much of the initial enthusiasm for computer navigation in TKA has waned as many of these systems have proved cumbersome, time consuming and expensive with no substantial evidence of a clinical benefit. Patient specific instrumentation is an additional option that is now widely available which seeks to harness some of the accuracy of computer navigation while improving intra-operative surgical efficiency. In 2015 there are now patient specific options available from multiple vendors and these vary in several different ways including: alignment goals; imaging modality; pin guide vs. cutting guide; all plastic vs. metal-plastic composite; and the degree of surgeon input into pre-operative planning. In all systems but one alignment is typically set relative to the mechanical axis; one system uses so-called kinematic alignment. Imaging can be done via CT, MRI, or MRI in conjunction with a hip-knee-ankle radiograph. The guides that are produced are typically made of a plastic material and in some cases are meant only to position pins onto which traditional metal cutting guides are then placed. In some systems the plastic guides come pre-assembled with an integrated metal cutting-guide that allows resection of the distal femur or proximal tibia in one step; in other systems cutting is intended to be carried out through a plastic captured guide. Finally there is wide variability in the degree of surgeon involvement in the pre-operative planning for the guides, ranging from no involvement in the so-called kinematic approach all the way to the ability for surgeons to dictate the depth, location, flexion-extension angle, varus-valgus angle, and rotation in some systems. At this point relatively little comparative data exists to objectively compare one system versus another.

Surgeons most likely to find substantial benefit from patient specific instrumentation are those who perform moderate numbers of TKA each year but who have inconsistent surgical scrub teams. For those surgeons, substantial surgical inefficiency can be attributable to the scrub team's unfamiliarity with the complex instrumentation needed for TKA. Patient specific instrumentation can bypass many of those relatively complex instruments and allow the surgeon to complete TKA in a timely and efficient manner. For TKA subspecialists, patient specific instrumentation may have an appeal from a precision standpoint or from an ease-of-room turnover perspective but are unlikely to yield major intra-operative time savings at this point. In the future, combining patient specific instruments with size-specific disposable instruments that are financially and environmentally favorable may make this technology more applicable to even broader groups of surgeons.

Deep periprosthetic infection after hip or knee arthroplasty is a disconcerting problem for patient and surgeon alike. The diagnosis of infection is sometimes obvious but frequently requires that the surgeon maintain a substantial index of suspicion for infection as the cause of pain or poor outcome after any joint arthroplasty. While surgical debridement with component retention is appropriate in a subgroup of patients with an acute periprosthetic infection most delayed and chronic infections are best treated with component resection. The pre-eminent role of two-stage exchange as the definitive treatment was established over 30 years ago. Two-stage exchange remains the gold-standard in treatment with an established track record from multiple centers and with multiple different types of infecting organisms. Some of the historical problems with two-stage exchange, such as limited mobility during the interval stage, have been mitigated with the development of effective articulating spacer techniques. Further, the emergence of drug resistant bacteria and the possibility of fungal infection make two-stage exchange the best choice for the majority of patients with deep periprosthetic joint infection in 2015.

Most discussions of alignment after TKA focus on defining “malalignment”; the prefix mal- is derived from Latin and refers to bad, abnormal or defective and thus by definition malalignment is bad, abnormal or defective alignment. No one then wants a “malaligned” knee. The intellectually curious, however, might switch the focus to the other end of the spectrum and ask what does an ideally aligned knee look like in 2015? Is there really one simple target value for alignment in all patients undergoing TKA? Is that target broad (zero +/−3 degrees mechanical axis) or is it a narrow target in which a penalty, in regard to durability or function, is incurred as soon as you deviate even 1 degree? Is that ideal target the same if we are evaluating the functional performance of the TKA versus the durability of the TKA or could there be 2 different targets, one that maximises function and one that maximises durability? Is that target adequately described by a single 2-dimensional value (varus/valgus alignment in the frontal plane) as measured on a static radiograph? Is that value the same if the patient has a fixed pelvic obliquity, a varus thrust in the contralateral knee or an abnormal foot progression angle?

It is revealing to ask “do we understand TKA alignment better in 2015 than in 1979…?” Maybe not. We allowed ourselves over the past 2 decades to be intellectually complacent in regard to questions of ideal alignment after TKA. The constraints on accuracy imposed by our standard total knee instruments and the constraints on assessment imposed by 2-dimensional radiographs made broad, simple targets like a mechanical axis +/− 3 degrees reasonable starting points yet we have not further worked to verify if we can do better. It is naïve to think that the complex motion at the knee occurring in 6-dimensions over time can be reduced to a single static target value like a neutral mechanical axis and have strong predictive value in regard to the success or failure of an individual TKA. We assessed 399 knees of 3 different modern cemented designs at 15 years and found that factors other than alignment were more important than alignment in determining the 15-year survival.

Until more precise alignment targets can be identified for individual patients or sub-groups of patients then a neutral mechanical axis remains a reasonable surgical goal. However, the traditional description of TKA alignment as a dichotomous variable (aligned versus malaligned) defined around the broad, generic target value of 0 +/− 3 degrees relative to the mechanical axis is of little practical value in predicting the durability or function of modern TKA.

Over the past decade there has been a shift in the approach to management of many femoral neck fractures. As noted by Miller et al. those trends are reflected in the practice patterns of surgeons applying for board certification through the American Board of Orthopaedic Surgeons. From 1999 to 2011 there was a trend toward total hip arthroplasty and corresponding small decreases in the use of hemi-arthroplasty and internal fixation for treatment of femoral neck fractures. For many years the treatment approach has been a simple diagnosis-related algorithm predicated upon classification of the fracture as displaced (historically treated with hemi-arthroplasty) or non-displaced (historically treated with internal fixation). More recently, however, the focus has shifted to a patient-centered approach. In the patient-centered approach factors such as age, functional demands, pre-existent hip disease and bone quality should all be considered. In the contemporary setting it is still important to distinguish between displaced and non-displaced fracture patterns. Non-displaced femoral neck fractures, regardless of patient age or activity, are well-suited to closed reduction and internal fixation, most commonly with three cannulated screws. The union rate is high in non-displaced fractures treated with internal fixation and the benefits of preserving the native hip joint are substantial. Displaced femoral neck fractures in younger active patients, particularly those without pre-existent hip arthritis, are best treated with early anatomic reduction and internal fixation. While a subgroup of young, active patients who undergo ORIF may fail, the benefits of native hip preservation in that group are again substantial. Displaced femoral neck fractures in older patients or those with substantial pre-existing hip arthritis are best treated with arthroplasty. The biggest practice change has been the trend to total hip arthroplasty as opposed to hemi-arthroplasty for a subgroup of patients. Total hip arthroplasty is now favored in almost all active, cognitively well-functioning patients as the degree of pain relief is better and the risk of reoperation is lower in the current era (32mm and 36mm femoral heads). Hemi-arthroplasty, either uni-polar or bi-polar, remains an appropriate treatment for cognitively impaired patients who also have limited functional demands in whom the risk of dislocation is particularly high.