Total Knee Arthroplasty



Total Knee Arthroplasty


Steven Haas, MD

Benjamin F. Ricciardi, MD

Davis V. Reyes, PT, DPT, OCS


Dr. Haas or an immediate family member has received royalties from Innovative Medical Products and Smith & Nephew; is a member of a speakers’ bureau or has made paid presentations on behalf of Smith & Nephew; serves as a paid consultant to Smith & Nephew; has stock or stock options held in Ortho Secure; has received research or institutional support from Smith & Nephew; and has received nonincome support (such as equipment or services), commercially derived honoraria, or other non-research–related funding (such as paid travel) from APOS Medical & Sports Technologies. Neither Dr. Reyes nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article.



Introduction

With the increasing number of total knee arthroplasties (TKAs) being performed in the United States each year, it is more important than ever that clear rehabilitation guidelines and principles be instituted in order to ensure success of the surgery. Such guidelines and principles should be based on stages of healing, objective measurements, best-practice therapeutic exercise progressions, clinical research, and typical time frames for the resolution of major impairments and achievement of functional milestones. Utilization of such guidelines and principles will allow for more effective management of the initial phases postoperatively and throughout the continuum of care. Physical therapists are challenged in today’s healthcare climate, in which progressive limitations in rehabilitation coverage each year require physical therapists to address a wide range of postsurgical impairments with fewer visits. The following is an overview of updated best-practice postoperative rehabilitation guidelines and principles.

TKA is a resurfacing procedure. The femur is resurfaced with a metal implant 8 to 10 mm thick. The tibia in resurfaced with a metal implant that accepts a polyethylene inset. The patella in resurfaced with a 7- to 9-mm polyethylene implant in most cases. The collateral ligaments are left in place to support the knee in most cases. The anterior cruciate ligament (ACL) is often absent or attenuated from the arthritis, and the remnant is excised. The posterior cruciate ligament (PCL) can be retained or substituted by the implant with equal success.

The indications for TKA are pain and/or dysfunction caused by cartilage damage to the knee. The most common reason is osteoarthritis, but other causes include rheumatoid arthritis, posttraumatic arthritis, and osteonecrosis. While the average age for a TKA patient is approximately 65 years old, patients in their 50s are more often undergoing TKA. This is likely due to increases in sports-related injuries and obesity rates in the United States. While there is no absolute age-related contraindication, TKA in patients under 40 is uncommon. Patients in their 80s and even 90s have been shown to benefit from TKA, but they must be medically cleared for the procedure.

Contraindications for conventional arthroplasty include active infection, poor bone stock (including acute fracture), and patients unable to comply with rehabilitation.


Surgical Procedure

Knee arthroplasty is performed through a midline approach, but may be modified based on preexisting incisions. The joint is opened by incising the extensor mechanism medially around the patella, starting in the quadriceps tendon. Alternatively, an incision is made into the vastus medialis, allowing lateral mobilization of the patella. With this access, the menisci are excised as well as the ACL. Depending on implant design, the PCL may be excised or retained. The collateral ligaments must be retained but may be mobilized, especially in the case of varus or valgus deformity. Cutting jigs then create precise cuts in the femur and tibia to ensure accurate alignment and good motion. The metal femoral and tibial component is fixed into place with cement. Soft tissue and collateral ligament balance is a critical component in ensuring stability. The modular plastic trays assist in adjusting soft-tissue tension. The patella may be resurfaced. The tracking of the patella is checked and may require a lateral release. Secure layered closure is critical to infection-free healing.


Postoperative Rehabilitation

Rehabilitation of knee arthroplasty is critical to a successful outcome. It allows the patient to overcome mobility, strength, and motion defects that have developed over time.



Acute Phase (First 3 Days–2 Weeks)

In the initial days after surgery, the goal is to functionally prepare the patient for a safe discharge home or to an inpatient rehabilitation center. The primary emphasis during this phase is on patient education, transfer training, gait training, stair training, initiation of knee range of motion (ROM), remedial strengthening of the involved lower extremity, and adaptive functional mobility. Preoperative “prehabilitation” can improve strength and ROM and aid in postoperative rehabilitation, especially in the acute phase. Preoperative therapy can also educate patients, allowing them to achieve their therapy landmarks more quickly and discharge from hospital sooner.


Patient Education

In the acute phase, patients are advised to be as active as tolerated in order to minimize deconditioning, improve upright activity tolerance, initiate functional ROM, and to regain general mobility. Patients are typically advised against sitting for extensive periods of time to avoid static positions that could foster stiffening of the involved knee. Patients should alternate between walking, sitting, and bed rest with leg elevation, with decreasing bed rest as time after surgery passes. Patients are also advised against excessive standing or walking. Although regular upright activity can maintain healthy functioning of peripheral vasculature, too much activity can exacerbate swelling, overwhelm peripheral vasculature, and be counterproductive to the healing process. A balance between activity and rest is necessary. The therapist will need to monitor individualized responses to activity and modify activity accordingly.

In addition to general activity guidelines, patients are instructed on elevation of the involved lower extremity and regular use of cold modalities in order to manage postoperative swelling and pain. When this is performed concomitantly with the intake of prescribed anti-inflammatory drugs and the optional use of compression stockings, postoperative swelling can be managed appropriately. There are a variety of cold mediums available, such as gel and ice packs, that simply provide cryotherapy, whereas some commercial devices combine cryotherapy with pneumatic compression for the intention of mobilizing edema. While there are advantages and disadvantages to both, there is currently no evidence that one form is superior in managing postoperative swelling in the initial phases or throughout the duration of recovery. The modality of cryotherapy itself, however, has been demonstrated to control generalized swelling, decrease muscle hypertonicity, and provide analgesic effects, which patients and therapists have found beneficial in efforts to recover ROM and manage pain throughout rehabilitation.

Another component of patient education in the acute phase of rehabilitation is advising the patient in the use of adaptive equipment for activities of daily living (ADLs) such as reachers, long-handled shoe-horns, and long-handled bath sponges, as well as sock aides that facilitate modified function. The use of such devices can be phased out as the patient increases ROM of the involved knee and regains strength, endurance, balance, and independent mobility.

In the acute phase and throughout all phases of postoperative rehabilitation, one of the hallmarks of physical therapy is teaching patients various functional movement strategies through transfer and gait training. Education is provided on proper mechanics of transferring into and out of bed as well as transferring into and out of chairs, car seats, and toilets with the use of adaptive equipment. If necessary, equipment such as raised seat cushions and raised toilet seats can be provided to facilitate sit-to-stand movement. Education is also provided on appropriate mechanics to initially negotiate stairs nonreciprocally and then reciprocally when adequate strength and ROM are achieved. Finally, educational instruction is provided on proper mechanics to reestablish normalized gait. A patient’s ability to execute these activities will be commensurate with the patient’s progress in knee ROM as well as level of strength and balance. Full independence and complete proficiency can be attained in 1 to 2 months in a motivated patient with a straightforward arthroplasty or can take upward of 3 to 4 months of intensive rehabilitation.


Range of Motion

Initiation of ROM in the acute phase is vital to the success of this surgery. Based on the literature, the following knee flexion ROMs are necessary to perform the associated functional activities:




























Walking 65°
Ascend stairs 65°
Descend stairs 90°–100°
Sitting and rising from a standard chair 95°–100°
Biking 105°
Kneeling 125°
Squatting >130°

It is important to remember that the single best predictor of postoperative ROM is preoperative motion. The providers must know patients’ pre- preoperative condition to accurately assess their postoperative progress and counsel appropriately for outcomes.

Attaining more than 130° of knee flexion after TKA will allow patients to perform the more difficult activities of kneeling and squatting. However, if a patient regains a minimum of 110° to 120° of knee flexion, one should be able to perform the more essential ADLs without difficulty. In terms of knee extension ROM, there are no studies currently that establish how much range is necessary to be fully functional and reflect a successful outcome. Ideally, patients should achieve 0° of knee extension because maintenance of a flexion contracture, especially one that is greater than 15°, has been shown to increase energy expenditure and increase the patient’s likelihood of developing clinical issues in both the involved and noninvolved knee. Patients can also develop clinical issues in the lumbar spine, hip, and ankle from compensatory movement. Initiation of knee ROM in the acute phase can be accomplished by employing a continuous passive motion (CPM) machine multiple times a day for various durations. Some postoperative protocols utilize such devices. Although
the efficacy of such machines in expediting ROM and improving functional outcome scores is questionable in the literature, they can provide the advantage of promoting early knee flexion and moderating pain through continuous reciprocal movement. The disadvantages are that such devices may increase blood loss and wound complications. They may even increase pain, undermine knee extension, and foster dependency on the device in regaining motion passively rather than doing so actively. Such devices are used in conjunction with assistive and active range of motion (AROM) exercises. Further improvements in ROM can be obtained by the patient stretching independently and by the therapist’s utilization of a wide spectrum of skilled manual techniques. Techniques such as passive light manual stretching of the quadriceps and hamstrings can help patients flex and extend beyond what they are willing to achieve independently and elongate immature fibrotic tissue. In this author’s clinical opinion, performance of passive knee flexion stretching supine or sitting is recommended, as these positions allow the therapist to maintain visual as well as verbal communication with the patient. When knee flexion stretching is performed prone, the benefit of visual communication is lost and the position itself puts unnecessary pressure on the knee. Other beneficial techniques include patellar mobilizations and soft-tissue massage, which can help break down adhesions, improve muscle extensibility, minimize pain, and mobilize swelling. All of these, when combined, can help progress ROM.


Strengthening

In the acute phase, remedial strengthening of the lower extremity is often initiated. It is accomplished with primarily open-chain exercises to moderate excessive weight bearing through the involved knee. Exercises in this stage of recovery are intended to activate and reeducate muscles that have been inhibited prior to and compounded as a result of surgery. The muscle group primarily affected is the quadriceps. Reeducation and strengthening can be accomplished through a progression of a combination of isometric, concentric, and eccentric exercises. A simple example of this is to position a patient sitting on a chair or at the edge of a bed with an ankle weight around the ankle for introduction of progressive resistance, if necessary. The patient is instructed to straighten the knee, which concentrically activates the quadriceps. The patient then holds the contraction isometrically at end range for several seconds (Figure 43.1). Finally, the patient lowers the leg twice as slow to eccentrically activate the quadriceps. Incorporating neuromuscular electrical stimulation via an electrical stimulation device, primarily when the patient presents with knee extensor lag, may assist in regaining quadriceps activation. Reeducation and strengthening of core, hip, and ankle musculature
simultaneously can ensure reintegration of complementary muscle activity and provide a more complete exercise program.






Figure 43.1 A, B, Photographs of seated active range of motion knee extension. Movement: The patient is seated and actively extends involved knee. Purpose: Remedial quadriceps strengthening by utilizing weight of lower limb as resistance. The movement/strengthening exercise can also used as an assessment tool by therapists to assess degree of quadriceps strength in early stages of recovery. If patients are unable to straighten the knee fully with full engagement of the quadriceps muscle, this indicates use of electrical stimulation to facilitate greater activation and recruitment. This approach has been proven by research to help in the recovery of quadriceps strength.


Pain Management

One of the main hindrances in progressing through all phases of rehabilitation is pain. Many patients are aware that they will experience varying degrees of postoperative pain despite the provision of pain medication. Many will assume that the level of pain they are experiencing is the level they will have to endure for the duration of their recovery. This should not be the case. During the formative stages of recovery, it is important for physical therapists to establish open communication with the patient to continually explore whether the patient’s pain medication regimen is adequate enough to allow toleration of not only daily activity but also the rigors of physical therapy. If it is not, encouraging the patient to consult with the surgeon and/or pain management team again is indicated. A recuperative pain service may be consulted to assist in managing postoperative pain after discharge from the hospital. Once pain is adequately managed, use of palliative soft-tissue techniques can assist even further with pain management. If the pain is not well controlled, the patient will have difficulty improving ROM, achieving functional milestones, and experiencing a successful outcome.


Subacute Phase: Postoperative Phase II (Weeks 2–8) and Postoperative Phase III (Weeks 9–16)

The primary emphasis during this stage is continuing to improve ROM and assisting the patient to regain the level of strength, endurance, and balance necessary to perform higher levels of daily functional activity. Examples of such activities include negotiating multiple flights of stairs as well as returning to and tolerating the demands of work. In light of projected trends, in which younger patients (<65 years old) will undergo arthroplasty as well as older patients being more active in later decades of life, the scope of this phase of rehabilitation has expanded. The goals can include assisting patients to achieve the foundation of strength, endurance, and balance in order to promote desired recreational activity.


Patient Education

Instructions are provided on modifying activity based on the patient’s progress with rehabilitation. Some patients who are highly motivated may be advised to scale back activity to allow adequate rest and to foster healing while others may need to be encouraged to actively participate in exercises to facilitate overall progress. Patients are advised to continue edema management with elevation of the affected leg in conjunction with the use of cryotherapy. If a significant amount of edema develops below the knee, patients may be encouraged to discuss with their medical doctor or surgeon whether compression stockings can be used as an adjunct to control swelling. As more ROM, strength, and balance are recovered, the use of assistive devices can be phased out and transfer and gait training is fine-tuned for normalized movement.

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Oct 14, 2018 | Posted by in ORTHOPEDIC | Comments Off on Total Knee Arthroplasty
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