Individuals suffering from chronic knee pain, functional limitations, or a combination of the two are the best candidates to explore TKA as a potential treatment option. In general, individuals older than 60 years are better candidates due to lower postoperative expectations and diminished requirements for more intense activities. In addition, knee prostheses have a finite survivorship, so younger individuals will likely require one if not two revision procedures from the daily “wear and tear” depending on how young they are at the time of surgery. TKA candidates must undergo a proper evaluation to make sure their medical history, physical examination, and radiographic findings are consistent, and the pain may be relieved and expectations met by TKA. Physicians should also be aware of any relative and absolute contraindications (see section below), so potential candidates could be appropriately excluded from TKA or better optimized to become a future surgical candidate.

Patients should proceed with TKA when they have met two criteria. First, they must be deemed appropriate candidates for the procedure. Second, they must have attempted and exhausted nonoperative treatment for the degenerative changes in their knee(s).⁶

Over the past 5 to 10 years, there has been a shift in focus on cost containment within our health care system. Among the biggest factors dictating the significant cost of TKAs are hospital length of stay and discharge to skilled facilities after surgery. In order to mitigate these costs, outpatient or “same-day” TKA became a popular trend among joint surgeons, taking place within hospitals and free-standing surgical centers. Though this new trend decreases the overall cost of the surgery, there are serious risks with TKA operations that must not be overlooked, and careful patient selection is necessary. There is no consensus at this time, but it is imperative that physicians adopt strong screening guidelines to select suitable patients for outpatient TKA procedures.

Currently, there lacks a significant amount of literature looking at outpatient, or less than 24-hour stay, TKA. One study by Sibia et al found that older, female patients with a history of atrial fibrillation or prior TKA on the contralateral side tended to stay in hospitals longer than their counterparts after TKA.⁸ Furthermore, patients with American Society of Anesthesiologists score of 3 to 4 or patients who could not ambulate the day of the TKA demonstrated a longer recovery time compared to patients without these issues. Several other studies confirmed age, gender, presence of atrial fibrillation, and preoperative ambulation status correlated with increased length of stay after the procedure.⁹,¹⁰,¹¹,¹² Contrary to this, an elevated body mass index (BMI) has surprisingly not been shown to increase the stay postoperatively.

Another study by Meneghini et al constructed an Outpatient Arthroplasty Risk Assessment (OARA) score to help identify individuals appropriate for outpatient total joint arthroplasty (TJA).¹³ They utilized the expertise of a high-volume arthroplasty surgeon and a
perioperative internist to risk stratify patients into low-moderate risk (score ≤ 59) and not appropriate for early discharge (score ≥ 60). Previously, the main classification systems used for TKA safety were ASA-PS (American Society of Anesthesiologists Physical Status Classification System) and CCI (Charlson Comorbidity Index). The former, ASA-PS, was a screening tool created by anesthesiologists to determine operative risk, but studies have shown great variability among physician-attributed scores compromising the effectiveness of the system.¹⁴ The latter, CCI, has been effective in predicting 1-year patient mortality, but it does not specifically account for severity of symptoms. This causes the scale to lose much credibility for predicting candidates for outpatient TKA procedures.¹⁵ The OARA score was specifically created for determining who can safely undergo outpatient or short-stay TKA. It takes in to consideration comorbidities relevant to TJA and has already been utilized successfully with over 2000 patients.¹⁶ This updated study reported a 100% positive predictive value and 98.8% specificity for predicting patients that are candidates for outpatient surgery if there OARA score is between 0 and 79.

As more studies looking at outpatient patient selection criteria surface, guidelines for the selection process will continue being refined in order to balance all the risks and benefits of proceeding with an outpatient TKA.

In order to cut health care costs, bundled payment and pay-for-performance models have become increasingly popular among orthopedic surgeons.¹⁷,¹⁸,¹⁹ With such payment models, readmissions, reoperations, and discharge to skilled facilities are additional expenses, leading physicians to be more selective in choosing candidates for elective procedures, such as TKA. In order to prevent physicians and practices from taking the brunt of the financial burden, tools to anticipate the satisfaction in TKA patients postoperatively are essential. Since this economic shift in health care is relatively new, only a few of these outcome predictive tools exist. Additionally, it only seems rationale that if we can predict which patients will be the most satisfied and have the least complications one can work to optimize outcomes. Further, those at higher risk for complications or being dissatisfied can be counseled or optimized to educate them on how to improve their candidacy for surgery. After all, TKA should be a partnership between the physician and patient, with, both parties having to work on their end to achieve high levels of success.

The earliest TKA satisfaction predictive tool by Van Onsem et al consisted of a survey with 10 patient-answered questions.²⁰ This survey showed high sensitivity and positive predictive value internally, but two independent, external studies were unable to validate the predictiveness of the survey.²¹,²² The discrepancies found between studies exhibit the difficulty in finding an appropriate, outcome prediction tool. In addition, the survey by Van Onsem contained only nonmodifiable risk factors, which prevent any potential patient optimization. Kunze et al recently published an 11-question survey with eight of the questions consisting of modifiable risk factors.²³ This would allow for patient optimization before TKA if the patient did not meet the initial satisfactory threshold for the surgery. It is crucial that all factors be considered to further work on better prediction models so that we work to not limit the access to care but rather, increase the likelihood of a successful TKA outcome.

With patient satisfaction being paramount to medicine, outcome prediction tools should continue being studied and utilized preoperatively to help limit complications and achieve the best results possible for all TKA patients. It is also vital to understand that while patient-reported outcomes are an important measure, one has to consider the whole picture including radiographic follow-up as these may be predictive of failure even in a patient that is doing well score-wise.

For certain patients, TKA may not be the best option. Patients with chronic pain, that may not be purely related to the knee joint itself, should consider going to a pain clinic for alternative options to treat their pain, since TKA may not resolve their symptoms. Patients with severe rheumatoid arthritis should consider rheumatologic treatment before proceeding with TKA. There also exist several alterative surgical procedures to TKA including osteotomy, unicompartmental arthroplasty, and arthrodesis. The procedures each have their own risks and benefits, which should be carefully weighed before to proceeding with any of these surgeries.

Osteotomy of the knee is appropriate in early degenerative joint disease in patients who have maintained full range of motion and good knee stability. The goal of this procedure is to redirect the weight-bearing portion of the joint from an area of degenerated cartilage to healthy, intact cartilage. Unicompartmental arthroplasty is appropriate for individuals with isolated medial or lateral arthritis without ligamentous instability, inflammatory arthritis, and minimal patellofemoral disease. Arthrodesis of the knee is rarely indicated (young, heavy laborer is the typical candidate) but remains an option for individuals with contraindications to TKA, such as active sepsis.

It is safe to say that in regards to TKA, surgeons have several expectations, but in the end, it boils down to, if I put the knee in correctly and it is well-fixed, then I would “expect” a successful outcome. Within these expectations
are the inherent assumptions that patients will follow the physical therapy orders, work hard, wean off their pain medications, be compliant with venous thromboembolism (VTE) prophylaxis, follow-up at appropriate time intervals, and be invested in their own care and outcome. However, in the editor’s spotlight by Dr Leopold, these assumptions are challenged as he posed the following question, “But is it possible that experienced surgeons have a no-better-than-chance likelihood of anticipating whether a patient undergoing one of the most common operations orthopedic surgeons perform—TKA—will improve enough to say the procedure is worthwhile?”²⁴ It was the study by Ghomrawi et al that spurred the asking of this question as their prospective study of eight high-volume orthopedic surgeons showed that for TKA, surgeon expectation scores were not accurate in predicting who would improve after surgery.²⁵ This is why it is critical that scoring systems are developed to help predict who will benefit from TKA so that surgeons are not just relying on a feeling or hunch that this patient is a good candidate for surgery and they will fulfill our ultimate expectations.

In this modern era of digital technology, it would seem that communication of a surgeon’s expectations could occur via numerous modalities prior to surgery in order to make sure that the patient was clear on what was “expected” of them. It is also clear that surgeons are aware of this need as most have turned to total joint classes, handbooks, digital applications, establishing a coach, wearable devices, etc., to reach out to patients and try to set expectations.

With patient-reported outcomes being tied to reimbursement, there is an even greater push to make sure all parties are on the same page and meeting expectations. Making sure your expectations are clear to a patient will take time and communication, which is in direct contrast to the modern practice of being a high-volume surgeon. However, patients often want to please their doctor and show them that they are recovering well, so using tools that set goals and remind patients that they are ahead or behind can be quite valuable in furthering this relationship. Gautreau recently came up with a surgeon-patient communication checklist for TKA that may offer an alternative avenue for patients and doctors to set expectations and goals for one another that are clear and well contrived.²⁶ In the end, this will likely improve satisfaction and help with the reduction in dissatisfied patients (as this stands at ˜20% currently).

While neither of the authors has had a TKA, it seems safe to say that reasonable patient expectations after TKA can be summarized as a reduction in knee pain, improved knee function, the ability to perform ADLs, restoration of disturbed sleep pattern, and the ability to return to some sporting activities. These are clearly attainable expectations but are by no stretch of the imagination the same as having no pain, restoring the ability to perform activities that they could do when they were younger but have not done in years, curing ailments in other locations, and being able to perform high-impact activities. If a patient was limited by spinal pathology or a remote condition from the knee, this will likely continue to limit them after a TKA and they should not anticipate returning to a higher level of function than this limiting factor. Additionally, there are no guarantees with surgery, and patients should understand their risk profile and the amount of work it will take to achieve their goals. If not there may be a failure to meet expectations and ultimately a dissatisfied patient. Another consideration is the timeframe for recovery as many are swayed by the fact that TKA is being performed as an outpatient, that this must be an easy and quick recovery. A recent study suggests that 1 year may be too short to be considered the final recovery and that physical and psychological support may be necessary to strive toward achieving a silent knee.²⁷

Lützner et al reported on a prospective randomized controlled trial (RCT) including 103 patients at 5 years after surgery.²⁸ They found that a higher knee score and fulfillment of expectations were correlated with higher satisfaction. Therefore it is critical to establish realistic expectations for each individual patient along with the timeframe at which they can anticipate recovery. The authors tend to take a harder line on these expectations, painting a difficult and relatively painful road to recovery. This often leads to patients overestimating the recovery, rather than being surprised by what it takes to reach full strength. We would rather have the patient state that was easier than I expected, than say I didn’t expect the recovery to be so hard. There is clearly a psychological nature to expectations, and it is important to incorporate this into your practice of indicating patients for surgery.

The last aspect of expectations includes the durability and longevity of TKA components. Patients should understand the importance of long-term follow-up and that a TKA will not last forever. The better they treat it (low-impact activity, maintaining a fit lifestyle, and regular follow-up), the longer it will likely last them. Modifying activities to keep them in the low-impact range can lead to excellent long-term survivorship. Abusing the knee by running, jumping, and high-impact activities will lead to a shorter lifespan of the replacement and revision surgery. While TKAs are currently expected to last 15 to 20 years, it is important after 10 years to make sure patients return for follow-up as wear may be relatively asymptomatic until it is “too late.” The authors like to set the expectation for follow-up prior to the initial surgery, so it is clear that the patient will assume responsibility for their joint replacement and remember to take care of it over time. Putting this out on the table early helps the patient and surgeon determine if they are truly ready for a TKA or should other treatment options be explored.

The most common complaint in TKA-eligible individuals is worsening knee pain in the affected joint that has been impacting their quality of life. This pain should be further defined based on location, timing of symptoms, and specific aggravating factors. Usually the knee pain is fairly localized early on in the pathological process, but end-stage arthritic pain can elicit pain referred several centimeters superior and inferior to the actual knee. Complaints of anterior thigh, groin, or foot pain are all indications of pathologies that are likely separate from the knee and require a thorough adjacent joint assessment. Anterior thigh and groin pain point to potential hip pathologies, while radicular pain should be suspected with complaints of pain radiating down the leg below the knee. Often the patient notes worsening knee and stiffness pain during the day and with activity, but as the arthritis progresses, the pain can persist throughout the night and at rest. If the patient complains of sudden-onset knee pain that constantly hurts and responds minimally to nonoperative treatment or night pain, the physician should have some degree of suspicion for joint sepsis or a local tumor (bone or soft tissue).

If knee pain occurs mostly with activity, specific movements and functional disability caused by the pain should be determined. In addition, the physician should work with the patient to elicit the value in continuing these activities in the future, for example, continuing to ski black diamond runs, playing full court basketball games, etc. This can help determine the appropriate treatment path, as if the activities the patient wants to return to are not compatible with what a TKA will provide, this may limit their candidacy for the procedure. All other aggravating factors for the knee pain should be elicited as well as how much this impacts crucial activities important to that specific patient. Some important factors to inquire about are the ability to perform activities of daily life such as cleaning, driving, stair climbing, personal hygiene, and sleeping. After obtaining a good baseline understanding of what the ultimate activity goals are, the physician can determine how suitable TKA is at the time (refer to expectations section, above).

Previous operative treatment to the affected knee and any nonoperative intervention for the knee pain are critical components of the history to elucidate. Any prior operative treatment could alter the decision and approach used in TKA, so operative reports should be obtained if accessible. Additionally, prior surgical procedures may give information regarding the integrity and presence of the cruciate ligaments as well as degenerative findings in all compartments of the knee (may be important when deciding on anterior cruciate ligament (ACL)/posterior cruciate ligament (PCL) retaining knees or unicompartmental knee arthroplasties [UKAs]). Nonoperative treatment can be broken into three different arenas: lifestyle management, pharmaceutical treatment, and interventional treatment. In lifestyle management, alterations in weight should be determined as this could alter the progression of the arthritic changes. Next, pharmaceutical treatment for pain or inflammation should be included in the history. Common pharmaceuticals include nonsteroidal anti-inflammatories and acetaminophen. Opioids should not be provided for the management of degenerative changes to the knee as this may make controlling postoperative pain more difficult.³⁰ AAOS clinical practice guidelines further recommend against opioid use since there is a lack of conclusive evidence exhibiting any benefits of opioids in the setting of knee osteoarthritis. Lastly, interventional treatment focused on prior physical therapy and knee injections should be elicited. The most recent injection, especially with corticosteroids, is important to determine since that could alter the scheduling of the TKA (potentially 6-week to 6-month delay).²⁵,²⁶,³¹,³² Furthermore, if an appropriate response is not found after an injection, it may be prudent to investigate other sources of the patient’s perceived knee pain. In general, all appropriate nonoperative measures should be attempted and determined to no longer be providing adequate pain relief and restoration of function before undergoing TKA.

The previous points have all mainly focused on the orthopedic history directly relating to the knee, but it is important not to have tunnel vision and dismiss pertinent medical history. Any adverse reactions to medications, specifically prophylactic antibiotics, are essential to determine to avoid potential surgical complications. Knowing any hereditary bleeding disorders or abnormal propensity
toward clotting can further help prevent issues during and after the procedure. Comorbidities, such as diabetes, high BMI, and lower back pain, have lower outcome scores postoperatively and higher potential risks, so all comorbidities should be recorded at the initial patient visit.³³ In addition, inflammatory arthritis may need to be considered as a potential cause of the knee pathology if a relevant history is present. If the patient has an inflammatory arthropathy, all disease-modifying antirheumatic drugs (DMARDs), affected joints, systemic manifestations, as well as preoperative range of motion should be documented. Interestingly, Kobayashi et al determined that inflammatory arthritis patient satisfaction improves after TKA greater than those with osteoarthritis even though their functional activity remains lower overall.³⁴ Bleeding disorders, comorbidities, inflammatory arthritis, and DMARDs are important history points to cover for each TKA candidate, and there are numerous other confounding issues that should be explored on a case-by-case basis (see contraindications section below). The patient history gives invaluable information about the pathological process, but it is only the first of three prongs in determining whether or not the patient is an appropriate candidate for TKA.

Physical examination should focus on overall gait, skin inspection, palpation of the joint, neurovascular status, range of motion, and ligamentous stability of the knee and adjacent joints.

An antalgic gait is common, and any excessive valgus or varus deformity should be noted particularly if leads to a medial or lateral thrust. Furthermore, a Trendelenburg gait can suggest the presence of hip pathology, which could be a source of referred pain to the knee. The foot should be assessed to look for excessive pronation or supination that can contribute to worsening standing alignment of the knee. Often the foot can accentuate a limb deformity at the knee and on occasion may need to be corrected prior to knee surgery. It is important to watch your patient ambulate, and this is often the first aspect of the physical examination you will notice as they stand up to move to introduce themselves. The act of standing up from the chair (or inability to do so) and how they initially move would be telling how limited the patient actually is.

Next, the skin around the knee should be inspected for any active lesions, prior incisions, or other abnormalities. Some lesions may even point to the cause of arthritis, as is the case with psoriatic arthritis. All active skin lesions around the knee should be closely monitored, since surgical intervention in the presence of such lesions is associated with high rate of postoperative infection.³⁵ Typically, standard arthroscopy portal scars can be ignored, yet open procedures about the knee must be respected and if possible to incorporate these scars (particularly if wide and associated with immobile skin) into the TKA incision. If there are multiple incisions, try to use the lateral most incision to gain access to the knee joint.

Palpation of the joint should follow in order to determine where there is tenderness around the knee joint and will be used to assess consistency with other findings of the preliminary examinations. Though knee tenderness can occur diffusely throughout the joint in the setting of arthritis, specific areas of tenderness can help surgeons decide the appropriate surgical treatment. Most commonly, anterior knee and peripatellar pain can indicate the need for patellar resurfacing, since not all surgeons routinely perform this during TKA. Additionally, patella stability and apprehensive nature of lateral pressure on the patella should be assessed and noted. Once tenderness has been assessed, a neurovascular examination should begin with palpation of dorsalis pedis and posterior tibial pulses. Abnormal pulses could indicate vascular disease, which could limit tourniquet use during TKA, as well as a preoperative vascular consultation. Preoperative neurological deficits should be noted so that any incidental neurological damage occurring during the procedure could be clearly denoted.

Lastly, the range of motion and any ligamentous abnormalities should be evaluated. Range of motion is imperative to measure, since most times preoperative range of motion is predictive of postoperative range of motion.³⁶,³⁷,³⁸ Furthermore, any flexion contracture or extensor lag should be clearly measured and recorded, as should recurvatum (this may impact the procedure, i.e., performed and implants needed). Patients often have a misconception that they are guaranteed to regain lost motion after TKA, so the physician should attempt to clarify this fallacy preoperatively. The discussion should estimate ±10° range of motion from what they initially have in the office (more or less may depend on the intensity or lack thereof with postoperative physical therapy). After assessing the range of motion, ligamentous stability should be tested to confirm intact medial collateral ligament (MCL), lateral collateral ligament (LCL), PCL, and ACL, as well as any varus or valgus deformities that could be flexible and can be corrected preoperatively. It is important to note physical examination findings in correlation with the history provided and ultimately the radiographs that are obtained to make sure the pain and symptom pattern are consistent.

In addition to examining the knees, the physician should do an assessment of the back as well as the hips since pain can often be referred to the knee from these areas. Using the information from the patient history as well as the physical examination, the physician should move on to the third and final prong for determining the appropriate TKA candidate—radiographic analysis.

Radiographic imaging is quintessential for confirming the arthritic etiology of the knee pain. It is important to
note that some studies show little correlation between the severity of arthritic changes and initial clinical symptoms.³⁹ Due to this, imaging alone cannot be used as a reliable surgical candidacy determinant. However, the worse the degenerative disease is radiographically, the earlier the patient will typically feel better postoperatively.⁴⁰ Alternatively, if imaging shows no arthritic changes, a different diagnosis should be considered as TKA may not be indicated for such a patient.

The traditional radiographic views obtained for suspected knee arthritis include standing anteroposterior, Rosenberg (skier’s view/flexed PA radiograph), lateral, and patellofemoral (Merchant or sunrise) views (Fig. 28-1).⁴¹ The anteroposterior view must be standing to allow for observation of joint space narrowing under physiological conditions. An anteroposterior radiograph with the knee flexed exposes any joint space narrowing in the posterior aspect of the femur, which is difficult to observe on any other view. The lateral view shows any osteophytes or subchondral cysts at the posterior aspect of the affected knee. The patellofemoral view depicts any arthritic changes associated with the patella as well as patella tracking. This is important since some surgeons may opt out of patellar resurfacing if the patella is minimally affected. A full limb length radiograph can be utilized to determine mechanical axis deviations, other bony deformities, as well as a quick look at changes in the patient’s hips and ankles. Bone defects, quality, and abnormalities should be looked for as this could impact the surgical candidacy of the patient and/or the implants that may be required for the procedure.

After obtaining the appropriate views, the pathognomonic signs of arthritis are joint space narrowing, subchondral cysts, subchondral sclerosis, and the presence of osteophytes.⁴² The Kellgren-Lawrence Classification System helped standardize the description of the osteoarthritis by creating a 0 to 4 grading scale. This scale allows clinicians to grade the knee in a simplified manner from 0 (no osteoarthritis present) to 4 (severe osteoarthritis present).⁴² The K-L classification system was used as one of the scoring criteria in a recently published predictive outcome scale for patient satisfaction after TKA.²³ In general, radiographic evidence helps confirm the arthritic process, but it should not be used as the sole screening tool for the disease. A recent study by Alosh et al attempted to look at radiographic findings that were predictive of patient satisfaction and found that lateral compartment osteophytes and lateral patellar osteophytes were strongly associated with patient satisfaction.⁴³

Patient history, physical examination findings, and radiographic analysis should all be used in conjugation to determine the TKA candidacy of each individual. Below will highlight conditions that warrant specific consideration when considering a patient a candidate for TKA with these concomitant findings on history, physical, or
radiologic examination. This will be followed with contraindications for TKA as we again look for the clear picture of all aspects corroborating a patient’s candidacy for the procedure.

Despite improving materials, pathways, and surgical techniques, it is important to consider a patient’s age prior to TKA as implants will likely not last “forever,” and with younger patients placing greater demands on the implants, there remains a question of how long and how much can they take. Charette et al recently reported a higher cumulative revision rate at 1 (3.4% vs. 1.8%), 2 (5.0% vs. 2.4%), and 5 (7.3% vs. 3.7%) years in patients younger than 55 years compared to those older than this age.⁴⁴ Another study by Karas and colleagues found a survivorship of 83.9% at 13 years for all-cause reoperations in patients between 45 and 54 years old.⁴⁵ In the 298 TKAs they reviewed, 20 died and 30 were lost to follow-up, leaving 248 knees. They found at an average of 13-year follow-up revisions occurred in, nine for tibial loosening, eight for deep infection, seven for polyethylene wear, and three for failed ingrowth of a cementless femoral component. Based on the fact that younger patients will likely need a revision in the future, and coupled with some of these early failure concerns, it is important to make the patient aware of these findings and risks prior to their TKA. The majority of cases are successful, yet these higher early to midterm failure rates are concerning. While younger age is not an absolute contraindication for TKA, it must be considered and discussed with the patient prior to surgery, as they may be likely signing up for one or two additional procedures in their lifetime.

At the other extreme, in the elderly, excellent results have been reported after TKA; however, these patients are typically not as healthy and require appropriate medical optimization and tight control of their comorbidities postoperatively. For the senior author (BL), it is not necessarily the number of the age but the whole package/physiologic age and concomitant comorbidities that have to be considered when indicating a patient for a TKA. Motivated elderly patients often outperform younger ones; and if carefully selected, octogenarians and nonagenarians can have successful results after TKA. Kodaira et al reported on 1003 TKAs in patients >80 years old at the time of surgery and found no different in improvements in outcomes scores.⁴⁶ An increased length of stay, confusion, delayed wound healing, and acute heart failure occurred more frequently in their elderly cohort.

As such for younger patients, specific considerations include the possibility of using cementless technology for long-term implant fixation, assuring appropriate alignment is achieved, and using the least amount of constraint possible in an effort to improve the longevity of the TKA construct. Alternatively, for elderly patients, meticulous care of the soft tissues (be careful with adhesive dressings and skin tears), tight control and optimization of comorbidities, management of potentially “soft” bone, and the use of cemented implants can help achieve successful results even for patients in their 80s and 90s.

Obesity is a growing epidemic in the United States and is partially responsible for the increasing number of TKAs being performed annually. In fact ˜37% of adults, or 1.12 billion people, are expected to be clinically obese by 2030, particularly among the developed countries in the world.⁴⁷ Clement and Deehan reported on 4740 TKAs and found that patients with increasing BMI class were noted to have an associated earlier age at the time of knee surgery.⁴⁸ Many overweight patients may be faced with the difficult task of trying to lose weight in the setting of a knee or knees that will not function to do higher level physical activity. A significant number of these patients revert to bariatric surgery to lose weight, which has controversial results with concerns for significant morbidity, malabsorption, and malnutrition after these operations. Further specifics for timing of such a procedure, also remains controversial and it is likely better for patients to work on weight loss without bariatric surgery. The senior author (BL) suggests a nutrition consult and referral for an exercise program for patients with a BMI over 40. Many of these patients, despite their weight in pounds, will be malnourished with suboptimal total protein and albumin levels. Ideally, a targeted weight loss program that is sustainable would be preferred to binge diets, with a goal to get below a BMI of 40 and closer to 35. Keeney et al reported that even losing a minimum of 20 pounds prior to TKA is associated with a shorter length of stay and decreased odds for discharge to nursing facility postoperatively.⁴⁹ Additionally, any associated medical comorbidities such as sleep apnea, peripheral vascular disease (PVD), lymphedema, and diabetes should be optimized preoperatively if they are present. It is important to take the whole clinical picture into consideration, and while not trying to restrict access to care, it is important that patients understand the significant added risk that obesity adds to their surgery. Unfortunately, restricting TJA from this population has not been successful in promoting weight loss and better incentives and programs are needed to optimize these patients.⁵⁰ This is a good
opportunity to turn “cherry-picking” into “cherry growing” by getting the patient the help they need prior to an elective surgery.

Despite the concerns for performing TKA in morbidly and super morbidly obese patients, there are reports of improved outcomes after surgery and with meticulous techniques only slightly higher rates of complications. This led Hakim and colleagues to suggest that morbid obese patients are appropriate candidates for TKA and can still enjoy significant benefit from the surgery.⁵¹ With many studies reporting excellent functional improvement in obese patients, there does seem to be a higher rate of periprosthetic infection in this cohort.⁵² Other associated complications in obese TKA patients include higher readmission rates, delayed/poor wound healing, superficial and deep infections, MCL injury, and extensor mechanism injuries.⁵³ Patients of all obesity classes should have these risks discussed with them in the light of the potential benefit and opportunity for risk reduction with weight loss (Table 28-1). As such, special considerations for obese patients include meticulous surgery in regards to the adjacent ligaments of the knee and the skin/soft tissues. Longer incisions and extensile approaches for exposure are important so as to not have excessive retraction on the MCL and patellar tendon. Further considerations include adding short stems to the femur and or tibia, leaving the patella unresurfaced, and the possibility of using intramedullary guides to make cuts (as the tibia and ankle may be hard to palpate).