Total knee arthroplasty (TKA) continues to be one of the most reliable methods for treating end-stage arthritis when nonoperative management has failed. Choosing which patients would benefit the most from this procedure is paramount to maximize subjective outcomes. Alternative surgical procedures to TKA may also be indicated, and they should be explored with the patient in select scenarios. This chapter focuses on the preoperative steps that should be undertaken in evaluating patients for TKA and discusses alternative nonarthroplasty options.
In general, the indications for a TKA include knee pain, mechanical instability, decreased range of motion secondary to pain, and the decreased ability to perform activities of daily living. Knee pain and the amount of knee pain during daily activities should be the primary consideration for TKA, with an improvement in function being a secondary consideration. Additionally, each insurance carrier may have a unique set of criteria that the patient must fulfill in the nonoperative setting before TKA. One should be wary of the patient who is considering a TKA mainly for improvements in range of motion or in the ability to perform a recreational event but who does not have marked pain with daily activities. The majority of patients will experience pain reduction after TKA with considerable improvement in knee function; however, an expectation of improved pain, but not necessarily completely resolved pain, should remain the main point of discussion with the patient in the preoperative period. Setting a preoperative expectation of improved pain relief, but possibly not complete resolution of pain, is important as many patients will still have some periods of discomfort that come and go postoperatively.
A description of the patient’s preoperative pain symptoms should be thoroughly recorded. This includes the severity of pain at rest and with activities such as stair use and the distance the patient is able to walk without pain. The use of preoperative narcotics or alternate analgesics, the use of an assistive device for ambulation, and pain that keeps the patient up at night or awakens them in the middle of the night are all important factors in determining the severity of a patient’s symptoms and whether a knee arthroplasty is a reasonable consideration. An accurate description of the changes in severity of the pain throughout daily activities can help the surgeon better understand provocative activities that cause pain. Severe pain and what activities provoke this severe pain should always be investigated thoroughly. In rare instances patients can be in constant and severe pain; additional sources of pain generation should be considered in those patients who have unrelenting and severe pain.
In addition to pain at rest the pain during specific activities should be evaluated. It is important to document what activities cause pain and what activities are unable to be performed because of pain. Identifying the activities the patient used to perform and the activities they would like to return to performing will guide preoperative expectation counseling. Delineation of pain during activities of daily living versus during sporting events or primarily recreational activities will help guide the preoperative discussion of pain relief. One of the most reliable indications for TKA is pain with simple daily activities that is interfering with quality of life. The expectation to return to normal daily activities is a reasonable one versus the expectation to return to high-level sporting performance that the patient may or may not be able to do after TKA. Symptoms that do not correlate with radiographic findings should be further evaluated, and caution should be considered when offering these patients the option of TKA.
A patient’s occupation should also be considered before performing a TKA. Patients whose occupation requires constant kneeling and climbing may not be well-suited for TKA. In this scenario counseling should be provided about the possibility of the patient not being able to return to the exact occupation or job description that they currently hold. The patient should also consider the option of job retraining or a less manually strenuous aspect of their current occupation, although many people under the age of 60 years will return to their previous occupation after TKA. The amount of time needed for postoperative recovery can be discussed at this time. A return to work 4 to 6 weeks postoperatively may be reasonable for patients who have a more sedentary job, whereas return to work at 8 to 12 weeks may be more realistic for patients who have strenuous jobs that allow for minimal breaks in the workday. This discussion will allow patients to plan their sick leave or time off from work with their employer. If the patient is near retirement age, they may elect to delay surgery until after retirement so as to not exhaust all sick leave and vacation time. Ultimately, the timeframe for return to work will be patient- and occupation-specific and variable based on the postoperative recovery process. Return to driving is another important consideration after TKA. Previous work suggests that reaction time to braking may return to normal around the 4- to 6-week postoperative time point, and this can be used as a guideline for resumption of driving.
Another important aspect of the patient’s history is their response to and frequency of intraarticular injections, physical therapy, bracing, and nonsteroidal analgesics. These nonoperative treatment modalities should be tried in most, if not all, patients before surgery. The length of pain relief obtained from intraarticular injections should be carefully documented. If a local anesthetic is included in the injection, the pain relief from the injection should be noted before the patient leaving the office. If marked pain relief is not obtained in the near immediate time frame after injection, alternate pain sources should be evaluated before consideration of TKA. Identifying which nonoperative treatment options have been successful and which have not is important to ensure that the surgeon does not recommend treatment options that have been tried and failed. This can frustrate the patient.
The use of preoperative narcotics must also be carefully considered. Preoperative narcotic use has been shown to decrease subjective postoperative outcomes, and these patients are more likely to continue narcotic use a year after surgery. Although literature suggests a decline in subjective outcomes with preoperative opioid use, it remains debatable whether or not to counsel patients about this to temper their postoperative expectations. Cessation of preoperative narcotic use is ideal and mandatory in some practices, but this may not be possible in all patients. One approach in counseling these patients is to clearly describe in layman’s terms the effects that chronic opioid use has on pain tolerance and perceived pain in the postoperative period in order to appropriately set postoperative expectations. The topic of opioid use is covered in more detail in the next chapter.
The patient’s medical history must be considered before surgery. Comorbidities that can be optimized should be identified. More specific recommendations on perioperative medical management will be discussed later in this book. It is important to understand the medical history when counseling patients on their perioperative risks of cardiac events, deep vein thromboses, unexpected pulmonary events, periprosthetic joint infections, anesthetic complications, and even death. Although perioperative outcomes after TKA have dramatically improved from the 1970s to 2020, the possibility of perioperative risks must be considered and thoroughly discussed with the patient during the preoperative discussion.
The physical examination begins with an initial observation of the patient’s gait and their ability to transfer from chair to standing and to climb onto an examining table. The amount of pain and dysfunction observed during these activities can be helpful adjuncts to the oral history. Observation of a varus or valgus thrust, recurvatum or hyperflexibility, quadriceps inhibition, or a fixed flexion contracture can additionally give insight into the expected complexity of the case.
Routine assessment of passive and active range of motion, the ability to correct the deformity, crepitus, and peripheral circulation is important. In a varus knee tenderness along both the medial joint line and posterior lateral soft tissues is often observed because of the stretching of the lateral tissues as the varus deformity progresses. With the leg in full extension, an anterior to posterior pressure applied to the patella and palpation of the medial and lateral facets of the patella with medial and lateral patellar tilt maneuvers may elicit pain. This finding gives insight into the sensitivity of the patellofemoral joint, which may influence the surgical decision-making process.
Evaluation of the skin and any previous skin incisions that will influence the surgical approach should be documented. In general, the oldest incision should be used if it does not result in an undo strain on the surgical approach. Otherwise, the oldest and most laterally based incision should be used because of the main blood supply of the cutaneous tissues originating from the medial aspect of the limb. Careful examination of the foot and lower leg should also be performed. Findings of open ulcers, severe lymphedema, or chronic cellulitis need to be addressed prior to any elective TKA because of the increased risk of periprosthetic joint infection in patients who have these conditions. These conditions should be considered contraindications to surgery until resolved or optimized. Additionally, patients with decreased sensation in their feet, or a history of decreased sensation, without a known diagnosis of diabetes should be screened with a hemoglobin A1c test. These issues will be discussed further in subsequent chapters ( Chapter 2, Chapter 3 ).
A hip examination should always be performed because of the possibility of referred knee pain. Branches of the obturator nerve and femoral nerve innervate the anterior hip capsule. In patients who have hip arthritis or hip pathology this nerve can become inflamed and result in referred pain to the knee. Knee pain with range of motion of the hip and minimal knee pain when knee motion is isolated should alert the surgeon to the possibility of a referred pain phenomenon.
The overreaction of the patient to perceived pain and pain out of proportion to provocative maneuvers should carefully be evaluated for either a secondary gain purpose or alternate sources of pain. Hyperanalgesia of the skin or noted skin changes may represent a complex regional pain type syndrome that may be exacerbated by TKA. History of depression or anxiety noted on the oral history may correlate with an overly anxious patient during the physical examination. Patients who have pain out of proportion to radiographic and physical examination findings may have poor subjective satisfaction after knee arthroplasty surgery.
Routine radiographs include weight-bearing anteroposterior (AP), lateral, and patellofemoral views and a notch or tunnel view. Long-standing radiographs are an additional and helpful adjunct to isolated knee radiographs. The long-standing films allow for an assessment of overall limb alignment, any proximal tibial or distal femoral remodeling that has occurred secondary to the arthritic process, the presence of hardware that may influence the surgery, and the presence of femoral or tibial shaft bowing that may influence intramedullary guides. It also gives a screening shot of the pelvis for hip joint pathology. The preoperative deformity noted on radiographs, along with the correctability of the deformity on examination, will give a good preoperative estimate of the soft tissue releases that may or may not be necessary during surgery. Additionally, if conventional instrumentation is being used, the measured angle between the femoral shaft axis and the femoral mechanical axis can be measured and used for determining the angle of the distal femoral cut. This angle may not always equal 6 degrees, which is the traditionally noted resection angle for the distal femoral cut. A more patient-oriented approach with a variable distal angle measurement based on this preoperatively measured angle may be indicated and has been shown to improve patient outcomes.
General bone quality can be observed on the radiographs, along with osteophyte formation, evidence of joint effusion, and any periarticular erosions that may indicate an inflammatory rather than routine osteoarthritic joint. Sclerotic changes on one side of the joint with relative decreased mineralization on the opposite side of the joint may indicate asymmetrical loading of the joint. Observation of the size and relative position of the bony anatomy, including medial femoral overgrowth or lateral femoral hypoplasia in the valgus knee, should also be noted. It is also important to identify the rotational alignment of the knee joint with the patella facing forward in the radiography. A knee with tibia vara remodeling and relative rotation can be recognized by an increasingly overlapped position of the fibula on the tibia. This can alert the surgeon that additional surgical considerations may be needed to properly balance the knee through component positioning and soft tissue balancing. Additionally, subluxation of the tibia laterally on a standing view may indicate ligamentous stretching or an incompetent anterior cruciate ligament (ACL).
On the lateral view, evaluation of the wear pattern in the medial and lateral joint lines is important to note. The medial tibial plateau is seen as a subtle concavity, whereas the lateral plateau is relatively flat. The lateral femoral condyle can best be identified by finding the linea terminalis, which is the delineation of the patellofemoral joint from the lateral tibiofemoral joint and has an observed subtle flattening on the condyle. A wear pattern on the posterior aspect of the tibia indicates a relative flexion contracture that may also be observed on physical examination. Joint effusions are best observed on the lateral radiograph and can be identified as an increased density or haziness in the suprapatellar pouch where a clear or black region would normally be located.
The standing tunnel view adds additional information about the knee joint space, especially in knees with seemingly mild arthritic changes on routine standing AP radiographs. Using the Rosenberg technique, the standing tunnel view is a posterior to anterior projection with the knee in approximately 45 degrees of flexion. This view allows visualization of the arthritic changes, specifically joint space narrowing, in partial flexion that may be more pronounced in the valgus knee. This more impressive joint space narrowing seen on the partial flexion standing tunnel view may also be identified in some patients who have varus deformity and otherwise mild arthritic changes seen on the routine standing AP radiograph. The addition of this view may increase the detection of arthritic changes that may otherwise go undetected in a subset of the population.
A thorough history and physical examination can aid the surgeon in appropriate selection of TKA candidates and identify patients whose comorbidities require optimization to maximize patient outcomes and decrease the risk of postoperative complications. Patients may be divided into two distinct groups: (1) those whose symptoms can be explained by physical and radiographic findings and (2) those who have symptoms out of proportion to the examination findings. In these latter patients alternate sources of pain generation should be evaluated, including a synovial disease process such as pigmented villonodular synovitis; bony pathology including routine bone bruising, nondisplaced fractures, or tumors; isolated articular cartilage or meniscal pathology; a regional pain syndrome; lumbar spine pathology; and sources of referred pain. Advanced imaging such as CT scan or MRI can identify many of these subtle pathologies, and in rare cases a diagnostic arthroscopy may be indicated.
Treatment Alternatives to Arthroplasty
TKA provides reliable improvements in function and pain relief by resurfacing the articular surfaces and improving overall limb alignment. When the articular surface remains intact with minimal wear patterns or damage, alternate procedures may be indicated to improve symptoms resulting from limb malalignment or overloading of the medial or lateral compartments. These procedures may include distal femoral osteotomy, proximal tibial osteotomy, or patellar realignment surgery. Limb realignment and joint preservation procedures may be indicated in the very young and active patient who does not have an inflammatory arthritic condition and with mild to moderate wear of one compartment of the knee.
Distal Femoral and Proximal Tibial Osteotomy
The goal of the osteotomy procedure is to unload the affected side of the knee joint and to load the relatively unaffected side of the joint by realigning the distal femur or tibia to change the overall mechanical axis of the limb and redistribute the forces through the knee during weightbearing. One of the first steps in determining whether an osteotomy is prudent is identifying where the main source of the limb deformity is occurring.
In the valgus knee the overall limb deformity tends to occur in the distal femur, and a varus-producing medial distal femoral closing wedge osteotomy just proximal to the adductor tubercle may be performed to correct this deformity. This allows for good bone-to-bone contact and improved healing potential at the osteotomy site. Closing wedge osteotomy, however, may be more technically challenging because the wedge resection needs to be carefully calculated preoperatively. Over- or underresection of the wedge is difficult to correct intraoperatively. An alternative to medial closing wedge varus osteotomy is an opening lateral wedge osteotomy with bone grafting of the osteotomy site. The opening wedge allows for a more controlled titration of the limb deformity correction. The tradeoff is an increased risk of nonunion postoperatively because of the need to bone graft the osteotomy site.
In the varus knee the anatomical deformity often arises from the proximal tibia resulting in relative tibia vara. A valgus-producing medial opening tibial wedge osteotomy is often performed in this setting and can provide satisfactory limb alignment correction. Just as in the distal femur, a proximal tibia lateral closing wedge osteotomy is an alternative to the medial opening wedge. This tends to be technically more demanding, introduces the need to address the proximal fibula, and can lead to more infrapatellar scarring with patella baja and a more distorted joint line for future knee arthroplasty. In some cases the overall contribution of limb deformity will be from both the distal femur and the proximal tibia, and a combined osteotomy may be indicated.
An osteotomy may be considered if there is relative isolation of the arthritic process in one aspect of the joint with minimal or mild arthritic changes in the opposite compartment, which will ultimately see increased loads and stress after the osteotomy procedure. Additional factors to consider include:
Life expectancy. Young patients who would be expected to outlive their knee prosthesis may consider an osteotomy to bridge them to a knee arthroplasty surgery or, in some scenarios, help them avoid this procedure. In young patients both loosening of the implant and wear of the polyethylene need to be considered.
Activity level. Patients who desire to perform very high-impact activities postoperatively may not be suitable candidates for TKA. The risk of periprosthetic fracture and rapid polyethylene wear in these patients may not outweigh the benefits of arthroplasty surgery.
Factors that are not necessarily contraindications to an osteotomy procedure include:
Mild patellofemoral disease or the presence of patellar osteophytes especially with minimal joint space narrowing. Some patients will have radiographic findings of patellofemoral arthritis but have minimal sensitivity or pain from the compartment, and they may still be indicated for an osteotomy procedure. A careful clinical examination to determine how much, if any, pain is coming from the patellofemoral joint should be performed.
The presence of mild arthritic changes in the opposite compartment. In the very young patient the benefits of osteotomy may still outweigh the risks of progression of the arthritic process in the compartment that is not being loaded during weightbearing. Preoperative counseling about the longevity of the osteotomy procedure and the potential for incomplete pain relief is imperative. The notion that this procedure may be a bridge to a knee arthroplasty later in life should be conveyed to the patient.
Knee instability factors must also be considered before an osteotomy.
A positive pivot shift or Lachman test may indicate ACL deficiency that may need to be addressed at the time of the osteotomy. In young active patients who have arthritis isolated to one compartment and symptomatic ACL instability an extraarticular ACL reconstruction may be indicated at the time of the osteotomy procedure. Modern intraarticular ACL reconstruction may also be considered as a staged procedure.
Patients who have a lax or damaged medial collateral ligament (MCL) in need of an osteotomy also pose a marked challenge. Reconstruction of the MCL with allograft or autograft may be indicated at time of the osteotomy. In some instances the resulting change in tension of the medial-sided tissues, if a lateral closing or medial opening wedge proximal tibial osteotomy is performed, may provide enough stability.
Intraarticular pathology such as meniscal damage or chondral defects can also be addressed at the time of surgery either in open fashion or arthroscopically. Multiple options are available as cartilage restoration procedures, and they should be done in conjunction with the osteotomy if indicated.
Several factors are clear contraindications to an osteotomy.
Advanced age where a prosthesis would likely last the remainder of the patient’s lifetime is one contraindication.
Patients who have limited range of motion and marked flexion contracture preoperatively will likely not obtain the clinical success of patients with satisfactory preoperative range of motion.
Arthritis secondary to an inflammatory disease process or marked synovial disease process should preclude patients from osteotomy consideration.
Uncorrectable knee instability due to ligamentous, capsular, and surrounding soft tissue injury is a contraindication. Additionally, alternative options should be considered for rough or a severely worn articular surface that results in a depressed joint surface.
These contraindications may lead many surgeons to consider arthroplasty options versus an osteotomy, especially with the improved success of unicompartmental knee arthroplasty (UKA) and cementless TKA. However, in patients in their 30s or early 40s an osteotomy should be considered and discussed prior to undertaking an irreversible procedure such as a UKA or TKA. Any discussion about osteotomy must include the facts that, in general, osteotomy is less predictable than TKA, may lead to incomplete pain relief, and may be a bridge to a TKA later in life. Also, it is important to consider the increased planning and possible difficulty of a future TKA after a periarticular osteotomy is performed.
Currently, the most common indication for knee arthrodesis is a patient who has failed multiple treatments and surgeries for periprosthetic joint infection. Although not a common procedure in modern practice, it may be the most reliable option in certain patient populations. Patients who have nonreconstructible extensor mechanism disruption or a paralytic condition of the femoral nerve may still benefit from this option.
When considering knee fusion, there must be a notion that the joint is so unreconstructible that a knee arthroplasty would not be a reliable option or that failure of the prosthesis (including a hinge or distal femoral replacing prosthesis) would be so imminent or catastrophic that a fusion would be a more reliable treatment option. Fusion after TKA is often more technically challenging than a primary knee arthrodesis because of the bone loss from a multiply revised knee. This may result in marked shortening of the limb or bone grafting of the defect. Internal fusion nails and external fixation devices are effective and should be used in this clinical scenario.
Ultimately, this option should be considered the final option for the treatment of knee pathology. Conversion of a knee arthrodesis to a TKA in the future is a technically difficult procedure with limited success and is usually not a viable option for most patients who have a fusion. Patients must understand there is obligatory shortening of the fused side of at least three-fourths of an inch to allow for adequate swing through of the limb and push off on the opposite side. This shortening may be even more severe if there is bone loss at the time of fusion surgery. They must also understand that fusion is performed mainly for pain relief and to obtain a stable knee rather than to provide a high-performing limb postoperatively.
Informed consent starts with the formation of a relationship with the patient and family to create an environment in which an open dialog can occur. Patient participation in the treatment decision-making process is paramount. The surgeon should offer guidance through discussion of the risks and benefits of the most reliable treatment options. Patient education packets and knee models in the office can help patients make an informed decision. A description of a TKA as a resurfacing of the knee joint surface rather than a complete replacement of all the bones in the knee is helpful. As not all patients learn in the same manner, information for patients to take home are often necessary.
As with any elective procedure, the surgeon should never pressure or urge patients to get a joint arthroplasty but rather should create a dialog that allows the patients to determine whether a knee arthroplasty is the correct procedure for them. The patient is the only one who knows how much pain they are in on a daily basis and can decide whether major surgery is worth the risks of the procedure. There is a fundamental difference between “offering surgery” and “recommending surgery” to patients.
It is important to describe a knee arthroplasty as a procedure that should markedly decrease knee pain but may not result in a “perfect” knee. The resulting knee kinematics after TKA do not recreate the normal knee kinematics of the native knee no matter what knee implant design or advanced technology is used. TKA should be offered as a reliable option to treat debilitating pain. It also generally affords good functional outcomes for performing daily activities. Although there is a subset of patients who are able to perform a higher level of recreational activities, this should not be guaranteed to the patient, and they must understand that they may have to give up certain recreational sporting activities postoperatively. A brief discussion of prosthesis longevity should also be undertaken, especially in the younger patient population. This may bring into consideration alternate nonarthroplasty surgical options or simply a continuance of nonoperative management of the arthritic process.
Although knee arthroplasty has come a long way in terms of rapid patient discharge, it still should be conveyed to patients that this is a major surgical procedure and appropriate risks and benefits should be discussed. A careful discussion of the risk of periprosthetic joint infection and what this would entail in regard to further surgical procedures and medical management should be had with the patient. Helping patients to understand the effects that diabetes, obesity, and smoking have on their risk of infection may help persuade patients to work on the medical comorbidities that are modifiable for them to be optimized before surgery. Additionally, other complications that could markedly affect postoperative recovery such as deep vein thromboses, cardiac events, and significant stiffness in the form of arthrofibrosis should be discussed with the patient. Although rare, a special discussion of peroneal nerve palsy should be had with all patients with valgus knee deformity. Additionally, patients should understand that full knee recovery may take 12 to 18 months and that they will notice changes in strength and function up to a year after the surgical procedure.
Ultimately, the final decision to undergo TKA must come from the patient. They must be comfortable with this decision and be both mentally and physically prepared for the procedure and its recovery. They should be comfortable that they have exhausted all other nonoperative options and that TKA is the next most reliable option to treat their long-standing chronic knee pain.