There is no straightforward answer as to “when to pull the trigger” and offer surgery to a patient with severe knee disease. Surgeons would require a patient to report chronic knee pain and has functional impairment before they proceed with an arthroplasty. How bad is the pain? Is a patient impaired enough? Are the radiographs bad enough? Is the patient too young or too old? Is the patient too overweight? Is the deformity severe enough? Some of these questions are extremely difficult to answer, and the answers have a large subjective component. Appropriate patient selection is probably one of the most understudied issues in surgery and one of the most frequent causes of suboptimal outcomes. As in all clinical medicine, history taking and physical examination are the cornerstones of making the right diagnosis and recommending the correct treatment. Additional studies such as plain radiographs, CT, and MRI have an important but secondary place in the decision-making process.
Although there is currently not a reliable “pain-o-meter,” every effort should be made to quantitate and qualify the pain that the patient is having. Details of the type, intensity, and nature of the pain should be noted. The nature of the pain needs to be described in simple terms such as dull, sharp, or electric in nature. Location and radiation of the pain and frequency and time of the day when it affects the patient are key elements. How this pain modifies the patient’s function is probably one the most crucial elements in the decision-making process. A detailed history of when the pain appeared and its relationship to spatial events is also very important. Medical legal issues can cloud the patient’s description of the problem. For instance, it has been reported that the effect of disability of patients who are receiving workers compensation can be linked with greater experience of pain and reduced treatment efficacy. Questions to be asked include: When did it begin? Did it appear spontaneously? Was there a traumatic event? Where is the location of the pain; has it gotten any worse since it began? How often is it present? When present, is the intensity the same or does it vary? Does the activity make it worse? Does it require the use of pain medication? How often? Does it wake the patient from sleep? In essence, the amount of detail for the symptom being described and how it affects the patient’s life will help identify how this problem is impairing the patient’s quality of life. Statements such as “severe pain that does not improve with medication and limits activities of daily living” are not as informative as “severe pain that deprives the patient of sleep, requires daily narcotic intake to slightly reduce its intensity, and exacerbates with minimal activity that can only be performed with the use of assisted devices.” Clearly, the latter is a description of a more severe disruption that will probably require surgery.
After all adjectives that better describe the current state of the patient’s pain have been outlined, focus needs to be directed toward the pain’s effects on function. It is essential to record activities the patient can do or is unable to do as a result of the knee problem. It is important to establish whether the limitations are directly related to the knee problem and not a consequence of other medical conditions (i.e., vascular insufficiency or heart disease). The need for assistive devices, the type of devices, and the patient’s dependence on the devices to perform activities of daily living should be clearly identified and documented. As with pain, a comprehensive characterization of the patient’s function will aid the surgeon in determining what intervention would be of greater benefit. It is appropriate to include a segment of the patient’s socioeconomic background at this time. If the patient is working, it will be important to determine how this condition limits their ability to perform their duties. A conversation on how surgery will affect the patient’s ability to work in their current job is important. The time to return to work will be different for someone who is an office clerk rather than a construction worker.
Severity of the functional impairment has been shown to affect outcome. Several reports have clearly shown that waiting too long to offer a patient knee replacement arthroplasty will result in a suboptimal outcome.
The patient’s socioeconomic and medical history will also be very helpful in the decision-making process. It is imperative that all medical events and problems a person has experienced and relevant health-related information be carefully explored and documented.
After establishing the status of the condition, expectations need to be discussed. It has been estimated that one in five primary total knee arthroplasty (TKA) patients is not satisfied with their outcome and that satisfaction (the strongest predictor) is primarily determined by unmet patient expectations. What does the patient expect to get out of this procedure? Do the expectations match what the procedure has clinically proven to achieve with regard to pain and function?
Another key aspect is a thorough understanding of the attempts to manage the problem without surgery. A detailed history of the use of antiinflammatory and analgesic drugs has to be obtained. The use of oral pharmacological agents to manage the patient’s problem needs to be documented, and in most cases these agents should be tried before offering surgery. The frequency and appropriateness of these oral pharmacological agents needs to be assessed by the surgeon. Intraarticular injections should also be tried before surgical intervention. The type and timing of any intraarticular injection needs to be noted because recent data have demonstrated an increased risk of infection after injections are performed within 3 months of a surgical intervention. Hyaluronic acid and corticosteroids are key modalities in the nonoperative management of severe knee pain. The use of platelet-rich plasma or stem cells remains controversial and has not been shown to be safe and effective in the treatment of arthritis. Additional modalities that need to be considered include physical therapy and bracing, although both of these are temporary solutions; their effectiveness has been questioned particularly in the face of severe radiological changes.
The opioid crisis in the United States clearly illustrates the importance of addressing narcotics and their use for any type of chronic pain that has a surgical solution. It has been well established that patients who have been exposed to high opioid doses for a prolonged period of time will display less favorable response to any pain management treatment after surgery.
Planning the postdischarge process after knee arthroplasty should be a key portion of the preoperative evaluation. The proper aftercare of patients requires a detailed assessment of the socioeconomic status of the patient. Having a significant other, having social support, and belonging to a faith group have been shown to improve outcomes. Attempts should be made to send the patient straight home after surgery. Several studies have shown that discharge disposition to home results in improved outcomes after TKA compared with discharge to skilled nursing facilities. It is imperative to determine the robustness of the patient’s support group. Information about living arrangements, availability of relatives to accompany the patient in the aftercare process, and rehabilitation will aid the discussion on how the patient can prepare in case of undergoing the procedure.
A detailed evaluation of the patient’s medical history must be performed. Most of these issues have been addressed in prior chapters. However, the importance of such information will elucidate not only the patient’s probabilities of surgical morbidity and mortality but also the potential for complications related to the procedure. Based on this fact (i.e., comorbid conditions), individuals can be classified into one of two groups: (1) medically stable ( Figs. 5.1 and 5.2 ) medically unstable. Patients who are medically unstable will require a multidisciplinary approach. In general, patients will require a preoperative workup that will contain a general medical evaluation including laboratory tests, electrocardiogram, and chest radiography. Drug history of the patient should determine which medication needs to be discontinued, bridged, and/or continued without negative effects. Sources of infection such as dental, dermatological, urinary, or respiratory must be ruled out. Age has not been found to be an absolute contraindication for surgery, however, age-related comorbidities should be considered.
In addition to the aforementioned, it is important to evaluate the patient’s nutritional status and vitamin D levels. Lavernia et al. have previously reported that there was a direct correlation between patients undergoing joint arthroplasty who presented preoperatively with low levels of total lymphocyte count (TLC: calculated by multiplying the total number of white blood cells by the percentage of lymphocytes) and albumin and increased length of stay, operative time, and resource consumption compared with patients with normal levels. Calcifediol is the serum marker commonly used to determine a patient’s vitamin D status. Although there is no consensus on what level defines the low end of the normal range and its associations with pathological conditions, research has shown that suboptimal levels of vitamin D are associated with lower preoperative and postoperative objective scores in total hip arthroplasty. Modification of most risk factors or personal habits that could lead to potential complications has been addressed in previous chapters.
In the set of complex cases ( Fig. 5.2 ) one can encounter patients with severe comorbid conditions that will require evaluation and clearance by a subspecialty physician. These may require specific additional testing such as echocardiogram and stress test for complex cardiac conditions and lower extremity Doppler studies in patients with previous deep vein thrombosis (DVT) or vascular insufficiency ( Fig. 5.3 ). There is an intricate relationship between the patient’s medical history and the intraoperative and postoperative planning as certain conditions will demand specific needs. Will this case require the use of specific blood loss prevention tools? Should the anticoagulation therapy be more aggressive due to this condition? Is there a need to prolong antibiotic use for this immunocompromised disorder? Due to the elective nature of TKA, optimization of all possible comorbid conditions will serve the patient better in minimizing the risk for complications during or after the procedure.
The physical examination is the cornerstone of the assessment pyramid. A number of conditions will mimic knee problems and will fool the surgeon into offering surgery to a patient who needs a spine procedure or a hip arthroplasty. Patients should be observed at all times while in the examining room. Careful analysis of the patient getting up from the chair, walking in the room, and getting on the examining table will help the surgeon determine the degree of disability. General appearance and hygiene is to be accounted for; inadequate oral and overall hygiene can lead to potential infection-related complications. The severity of a deformity can be assessed on weight-bearing and during gait. This important part of the assessment can also reveal the overall strength, disability, and discomfort the patient is experiencing as a consequence of the condition.
A detailed examination of the extremity and assessment of the status of the skin (i.e., presence of previous incisions, sites of superficial infection), range of motion, ligament balance, stability, and patellar tracking will relate to the surgeon’s ability to estimate technical difficulty, which is essential in the planning process. A large number of prior surgeries or a transverse incision around the knee may be an indication for a plastic surgery consultation. Muscle and rotational flaps need to be considered when encountering this scenario. Peripheral circulation and the presence of vascular insufficiency are important aspects to consider as they can also lead to potential complications. All the examinations need to include a detailed hip examination. The hip should be examined with the patient supine and sitting down. Although spine, hip, and knee disease can coexist, it is important to determine which one to address first. A practical way to determine which joint is responsible for most of the patient’s symptomatic presentation is an injection of local anesthetic into the knee or the hip; identifying the location that results in the most positive relief of the patient’s symptoms provides a better understanding of the path to take. Although the reports of knee pain can be confirmed, the decision of which condition to be addressed first must be discussed or evaluated in depth to determine what intervention would bring the greatest benefit.
A thorough neurological examination is also needed. It should include the assessment of reflexes, sensation, and presence of clonus or pathological reflexes such as Babinski.
Patient evaluation for TKA requires routine radiographic imaging, which will help assess the severity of the disease and confirm the diagnosis. Weight-bearing anteroposterior (AP), lateral, intercondylar or notch, patellofemoral, and, ideally, long standing weight-bearing views should be performed.
The AP view should be obtained with the patient in a standing position. Assessment of joint space of both the medial and lateral compartments can help determine the amount of cartilage damage. The varus and valgus alignment and degree of the deformity will affect the technical aspects of the procedure. Bone quality, presence of associated osteophytes, and subchondral changes are also to be noted; these can be related to degenerative changes. These findings might not be as evident in patients who present with an inflammatory condition ( Fig. 5.4 ).
Long standing AP weight-bearing views of the lower extremities can help assess the overall mechanical alignment of the lower extremity. The mechanical alignment refers to the angle formed by a line drawn from the center of the femoral head to the medial tibial spine and another line from the tibial spine and the center of the ankle joint. This angle should be approximately 5 to 6 degrees for men and 6 to 7 degrees for women. It is essential to ensure that the patient is in neutral rotation of the legs to obtain the most accurate measurements. This view allows determination of the varus/valgus alignment of the knees, leg length discrepancy, and the presence of extraarticular deformities (i.e., bowing of the femur or tibia). An asymmetrical enlargement of one knee noted on a long standing view suggests the presence of a flexion contracture. This finding must be recorded as it implies the potential for increased difficulty during the procedure and an automatic adjustment in the amount of bone taken from the femur. This hip-to-knee-to-ankle view is key in the complete evaluation of the mechanical axis of the extremity. This view allows the visualization of any coronal curvature in the tibia or femur and any disease in the hip or ankle joints. This curvature on the femur or the tibia will affect the cutting angle on the transverse cuts of both the femur and the tibia when the anatomical axes are used to make the bony resections. At this point, it is important to clarify the difference between the anatomical axis and the mechanical axis of each individual bone as well as the extremity ( Fig. 5.5 ). The mechanical axis is used and represents the static mechanics of the leg. The anatomical axis is used in surgery to make the transverse cuts to both bones, tibia and femur. These cuts are key determinants in the coronal orientation of the extremity. Another important parameter to evaluate in these coronal views is the joint line orientation ( Fig. 5.6 ). Any major deviation of the joint line from the horizontal will result in abnormal kinematics in the gait cycle.