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.

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:

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.

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.

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.

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.