Total knee arthroplasty (TKA) is a commonly performed surgical

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1 WHITNEY MEIER, DPT, OCS 1 PhD, MPT 2 PT, PhD, OCS 3 PT, PhD, ATC 3 MD 4 PT, PhD, CHT 5 Total Knee Arthroplasty: Muscle Impairments, Functional Limitations, and Recommended Rehabilitation Approaches Total knee arthroplasty (TKA) is a commonly performed surgical procedure designed to alleviate knee pain and improve function in individuals with knee osteoarthritis (OA) or rheumatoid arthritis. More than TKAs are performed each year in the United States and this number is expected to nearly double by ,69 Despite the high incidence of knee replacement and the availability of postoperative rehabilitative approaches, the resultant muscle impairments are not well defined and are an understudied area of postoperative care. 1 Of particular interest to rehabilitation professionals is the acute profound postoperative deficit in quadriceps muscle strength 5,42,52,55,67,70,79,85 The number of total knee arthroplasty (TKA) surgeries performed each year is predicted to steadily increase. Following TKA surgery, self-reported pain and function improve, though individuals are often plagued with quadriceps muscle impairments and functional limitations. Postoperative rehabilitation approaches either are not incorporated or incompletely address the muscular and functional deficits that persist following surgery. While the reason for quadriceps weakness is not well understood in this patient population, it has been suggested that a combination of muscle atrophy and neuromuscular activation deficits contribute to residual strength impairments. Failure to adequately address the chronic muscle impairments has the potential to limit the long-term functional gains that may be possible following TKA. ( ) that fails to completely resolve even years after surgery 5,6,29,71,72,85 ( 2). Hamstring strength deficits have also been reported after TKA surgery 5,29,42,51,72 ; however, the focus on the quadriceps is due to the association of the quadriceps Postoperative rehabilitation addressing quadriceps strength should mitigate these impairments and ultimately result in improved functional outcomes. The purpose of this paper is to describe these quadriceps muscle impairments and to discuss how these impairments can contribute to the related functional limitations following TKA. We will also describe the current concepts in TKA rehabilitation and provide recommendations and clinical guidelines based on the current available evidence. Therapy, level 5. J Orthop Sports Phys Ther 2008;38(5): doi: /jospt electrical stimulation, rehabilitation, quadriceps strength, total knee arthroplasty, TKA to normal functional activities such as walking and stair climbing. 5,29,42 Therefore, quadriceps weakness will be the focus of this clinical commentary. While the reason for quadriceps weakness is not well understood in this patient population, it has been suggested that a combination of muscle atrophy and neuromuscular activation deficits contribute to residual strength impairments. 54 Failure to adequately address the chronic muscle impairments is potentially limiting the long-term functional gains that may be possible following TKA. Despite the ubiquitous muscle impairments following TKA, long-term functional outcomes are depicted by both favorable and nonfavorable results. In general, self-report functional questionnaires, like the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Medical Outcome Study 36-Item Short Form Health Survey (SF-36), show large improvements following TKA. 21,26,33,35,43,45,61,64 Despite quite dramatic improvements in pain and perceived function, people who have had TKA for advanced knee arthritis have lower scores compared to individuals without knee problems. 18,59 In contrast to self-reported outcomes, functional performance measures, such as a timed 1 Clinical Faculty (Instructor), Department of Physical Therapy, University of Utah, Salt Lake City, UT; Physical Therapist, Department of Orthopedics, University of Utah, Salt Lake City, UT. 2 Assistant Professor, Department of Physical Therapy, Eastern Washington University, Cheney, WA. 3 Associate Professor (Clinical), Department of Physical Therapy, University of Utah, Salt Lake City, UT; Physical Therapist, Department of Orthopedics, University of Utah, Salt Lake City, UT. 4 Associate Professor, Department of Orthopedics, University of Utah, Salt Lake City, UT. 5 Associate Professor, Department of Physical Therapy, University of Utah, Salt Lake City, UT; Adjunct Associate Professor, Department of Exercise and Sport Sciences, University of Utah, Salt Lake City, UT; Adjunct Associate Professor, Department of Orthopedics, University of Utah, Salt Lake City, UT. Address correspondence to Dr Paul C. LaStayo, Department of Physical Therapy, University of Utah, 520 Wakara Way, Salt Lake City, UT paul.lastayo@health.utah.edu 246 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy

2 Quadriceps Strength Deficits Compared to Uninvolved Side up to 6 Months Following Total Knee Arthroplasty Berman 5 (n = 68) 63 Preoperative Isokinetic 60 /s mo postoperative Lorentzen 42 (n = 60) 74 Preoperative Isokinetic 30 /s mo postoperative mo postoperative Preoperative Isokinetic 120 /s mo postoperative mo postoperative Rodgers 67 (n = 20) 68 Preoperative Isokinetic 60 /s mo postoperative mo postoperative Lorentzen 42 (n = 60) 74 Preoperative Isometric mo postoperative mo postoperative Mizner 52 (n = 40) 64 Preoperative Isometric mo postoperative mo postoperative mo postoperative mo postoperative * Percent difference calculated: [(uninvolved TKA)/uninvolved] 100. stair-climbing or walking test, depict only modest improvements following TKA, 56,81 and substantial residual deficits persist when compared to age- and sex-matched healthy comparison groups. These functional performance findings are consistent in those with chronic quadriceps muscle weakness. 59,80,85 At times, the deficits in functional performance are quite pronounced. For example, approximately three quarters of patients with a knee replacement report difficulty negotiating stairs 59 and the average stair-climbing speed is only half as fast compared to healthy counterparts. 85 Furthermore, following a peak in functional recovery 2 to 3 years after TKA, there is an accelerated decline in function relative to typical age-related decrements. 66 Physical therapy countermeasures seem ideally suited to mitigate the muscle impairments and functional limitations following TKA. Recent descriptions of postoperative rehabilitation programs with intensive exercise following TKA have reported greater restoration of quadriceps strength, improved functional ability, and an earlier return to activity compared to historical TKA outcomes. 52,58,62,72 The purpose of this clinical commentary is 4-fold: (1) to describe the quadriceps strength impairments related to TKA and the associated muscle activation deficits and muscle atrophy; (2) to explore how these impairments contribute to functional limitations; (3) to describe how the current concepts in TKA rehabilitation are attempting to address these impairments; and (4) to outline recommendations and clinical guidelines for rehabilitation based on the best available evidence and therapeutic exercise principles. Quadriceps weakness has been implicated in the development and progression of knee OA 9,74 and is related to a decline in physical function. 15,20,27,32,73 People with knee OA-induced quadriceps weakness consistently exhibit about a 20% strength deficit compared to healthy age- and sexmatched cohorts. 73 Strength deficits are ubiquitous in people with advanced knee OA who are considering a TKA. Muscle strength assessments in patients with TKA are performed with isometric or slow isokinetic testing speeds. A compilation of these quadriceps strength results before and after (short- and long-term follow-up) TKA is provided in and 2. The most common surgical approach during a TKA procedure involves an incision through the extensor mechanism. This surgical approach apparently compounds preoperative strength deficits as patients produce less than half of their preoperative torque values at 1 month after TKA. 52,54,57,79 While quadriceps strength increases steadily thereafter, significant changes in strength start tapering off 6 to 12 months following surgery ( and 2). Hence, while isometric quadriceps strength improves 10% to 20% from preoperative levels following journal of orthopaedic & sports physical therapy volume 38 number 5 may

3 Quadriceps Strength Deficits From 6 Months to 13 Years Following Total Knee Arthroplasty: Comparison to the Uninvolved Side or an Age-Matched Healthy Group* Berman 5, 7-12 mo Isokinetic, 60 /s mo mo Huang 29, 6-13 y Isokinetic, 120 /s Isokinetic, 180 /s Walsh 85, 1.7 y Isokinetic, 90 /s Isokinetic, 120 /s Silva 72, 2.8 y Isometric, 75 of knee flexion Berth 6, Preoperative Isometric, 90 of knee flexion Postoperative (2.8 y) * Percent difference calculated: ([healthy TKA]/healthy) 100. mean age, 63; n = 68. TKA, n = 36 (mean age, 68); age-match, n = 9 (mean age, 63). TKA, n = 16 (mean age, 65); age-match, n = 10 (mean age, 62). TKA, n = 31 (mean age, 64); age-match, n = 40 (mean age, 63). TKA, n = 50 (mean age, 66); age-match, n = 23 (mean age, 63). TKA (85-95 Nm), 6,72 strength rarely ever reaches the value of age-matched healthy individuals ( Nm) 6,72 or the potential isometric or isokinetic strength levels of the nonoperative knee extensor muscles ( Nm). 5,6,42,52,85 At times, the amount of residual weakness in individuals following TKA is substantial in that a general strength deficit of 20% or more is common ( ). Some caution must be exerted when interpreting results that use the uninvolved limb as a comparator. Approximately 40% of patients with unilateral TKA progress to a TKA in their nonoperative lower extremity by 10 years 48,65 ; hence, the uninvolved knee should probably not be considered a typically healthy or unimpaired joint. Consequently, these estimates of weakness are conservative. 23 Accordingly, when comparing the long-term strength outcomes of TKA to healthy age-matched groups, 40 the strength deficit grows to between 30% and 48%. 23,52,53,85 In summary, the quadriceps strength deficits prior to surgery are greatly compounded early after surgery and slowly recover to levels only slightly better than preoperative values. Thus, pre-existing quadriceps weakness is not resolved solely by TKA and strength values post surgery are far from age-matched normative values. Quadriceps muscle weakness in patients with OA of the knee is attributed in part to failure of voluntary muscle activation (ie, muscle inhibition). 79 The failure of voluntary activation of skeletal muscle is defined as the inability to produce all available force of a muscle despite maximal voluntary effort. 36,75,76 There are 2 common techniques for equating failure of voluntary activation: twitch interpolation and burst superimposition. The twitch interpolation procedure is performed by superimposing a single or multiple pulses on various intensities of muscle contractions from 0% (resting) to 100% maximal voluntary contraction (MVC). Failure of voluntary activation is computed as 1 (superimposed twitch at MVC/superimposed twitch at rest). A burst superimposition technique is more commonly used to determine the levels of voluntary activation 54,57,78 by superimposing a train of high-voltage pulses with rapid frequency on a MVC. Failure of voluntary activation of the quadriceps using burst superimposition is frequently reported as an index called the central activation ratio (CAR). 36 The CAR is derived by dividing the maximal voluntary force by the total force achieved via a voluntary effort plus potential electrically elicited force ( ). A CAR of 1.0 denotes complete activation of the muscle. 36 Healthy older adults (66 to 83 years of age) with no known knee pathology have been reported to have a range of CAR values ( ), with an average CAR of ,49,77 When interpreting the studies using superimposed electric stimulation techniques, it is important to consider the relationship between the CAR and voluntary effort. 49,76 The calculated CAR may be lower than the true CAR, and the failure of voluntary activation may be overestimated. Failure of voluntary muscle activation plays a substantial role in the weakness that is present both before and after TKA surgery. 6,7,23,57,79 Prior to TKA the average failure of voluntary activation is more than twice that of healthy older 248 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy

4 TABLE 2 Quadriceps Strength Deficits From 6 Months to 13 Years Following Total Knee Arthroplasty: Comparison to the Uninvolved Side or an Age-Matched Healthy Group* Difference Difference Reference Time Test Mode TKA (Nm) Uninvolved (Nm) Healthy (Nm) Uninvolved (%) Healthy (%) Berman 5, 7-12 mo Isokinetic, 60 /s mo mo Huang 29, 6-13 y Isokinetic, 120 /s Isokinetic, 180 /s Walsh 85, 1.7 y Isokinetic, 90 /s Isokinetic, 120 /s Silva 72, 2.8 y Isometric, 75 of knee flexion Berth 6, Preoperative Isometric, 90 of knee flexion Postoperative (2.8 y) * Percent difference calculated: ([healthy TKA]/healthy) 100. n = 68 (mean age, 63). TKA, n = 36 (mean age, 68); age-match, n = 9 (mean age, 63). TKA, n = 16 (mean age, 65); age-match, n = 10 (mean age, 62). TKA, n = 31 (mean age, 64); age-match, n = 40 (mean age, 63). TKA, n = 50 (mean age, 66); age-match, n = 23 (mean age, 63). TKA (85-95 Nm), 6,72 strength rarely ever reaches the value of age-matched healthy individuals ( Nm) 6,72 or the potential isometric or isokinetic strength levels of the nonoperative knee extensor muscles ( Nm). 5,6,42,52,85 At times, the amount of residual weakness in individuals following TKA is substantial in that a general strength deficit of 20% or more is common (TABLE 2). Some caution must be exerted when interpreting results that use the uninvolved limb as a comparator. Approximately 40% of patients with unilateral TKA progress to a TKA in their nonoperative lower extremity by 10 years 48,65 ; hence, the uninvolved knee should probably not be considered a typically healthy or unimpaired joint. Consequently, these estimates of weakness are conservative. 23 Accordingly, when comparing the long-term strength outcomes of TKA to healthy age-matched groups, 40 the strength deficit grows to between 30% and 48%. 23,52,53,85 In summary, the quadriceps strength deficits prior to surgery are greatly compounded early after surgery and slowly recover to levels only slightly better than preoperative values. Thus, pre-existing quadriceps weakness is not resolved solely by TKA and strength values post surgery are far from age-matched normative values. Quadriceps Muscle Activation Failure Following TKA Quadriceps muscle weakness in patients with OA of the knee is attributed in part to failure of voluntary muscle activation (ie, muscle inhibition). 79 The failure of voluntary activation of skeletal muscle is defined as the inability to produce all available force of a muscle despite maximal voluntary effort. 36,75,76 There are 2 common techniques for equating failure of voluntary activation: twitch interpolation and burst superimposition. The twitch interpolation procedure is performed by superimposing a single or multiple pulses on various intensities of muscle contractions from 0% (resting) to 100% maximal voluntary contraction (MVC). Failure of voluntary activation is computed as 1 (superimposed twitch at MVC/superimposed twitch at rest). A burst superimposition technique is more commonly used to determine the levels of voluntary activation 54,57,78 by superimposing a train of high-voltage pulses with rapid frequency on a MVC. Failure of voluntary activation of the quadriceps using burst superimposition is frequently reported as an index called the central activation ratio (CAR). 36 The CAR is derived by dividing the maximal voluntary force by the total force achieved via a voluntary effort plus potential electrically elicited force (FIGURE). A CAR of 1.0 denotes complete activation of the muscle. 36 Healthy older adults (66 to 83 years of age) with no known knee pathology have been reported to have a range of CAR values ( ), with an average CAR of ,49,77 When interpreting the studies using superimposed electric stimulation techniques, it is important to consider the relationship between the CAR and voluntary effort. 49,76 The calculated CAR may be lower than the true CAR, and the failure of voluntary activation may be overestimated. Failure of voluntary muscle activation plays a substantial role in the weakness that is present both before and after TKA surgery. 6,7,23,57,79 Prior to TKA the average failure of voluntary activation is more than twice that of healthy older 248 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy

5 Force (N) MVIC + E MVIC MVIC 212 N CAR = = = 0.86 MVIC + E 246 N Time (s) A schematic representation of a quadriceps force tracing from a maximal voluntary isometric contraction (MVIC) with an electrically elicited force during a burst superimposition (MVIC + E). The central activation ratio (CAR) is derived by dividing the maximal voluntary force by the total force achieved during a combined voluntary effort plus any additional electrically elicited force. Quadriceps muscle impairments and lower extremity OA are associated with functional limitations and slower mobility performance in older adults. 41 The primary goals of a TKA are to decrease pain, improve functional mobility, such as walking and stair climbing, and to promote return to physical activity. TKA has been shown to be very effective in reducing the knee pain associated with arthritis 1,34,46 ; but 30% of patients report dissatisfacadults. 54,63,79 One month following TKA, the quadriceps activation deficits are twice from preoperative levels and the average CAR of people with TKA is roughly ,57,79 This level of quadriceps muscle activation failure is unusually large. As a reference, those with patellar contusions have a CAR of and individuals with acute (6 weeks) anterior cruciate ligament tears average As previously stated, the acute loss of quadriceps strength is dramatic and the reduction in voluntary muscle activation accounts for 65% of the variance in this loss of strength. 57,79 In fact, voluntary quadriceps activation failure contributes almost twice as much to the acute decrease in quadriceps strength as compared to the amount of quadriceps muscle atrophy. 57,79 Large activation deficits are of particular concern to physical therapists, as these patients typically experience only modest strength gains with exercise interventions. 30 It appears that voluntary activation failure can continue for an extended period of time after surgery for a subset of TKA recipients. Gapeyeva and colleagues 23 reported average quadriceps activation levels did not improve in female TKA recipients from the preoperative time point until the sixth postoperative month. Even with upwards of 8 days of formal rehabilitation, activation levels remained lower than those of healthy subjects. 23 A similar lack of activation improvement up to 6 months following TKA was also reported by Berth et al. 7 Twenty patients who were scheduled for bilateral TKAs had each knee randomly assigned to receive either a subvastus or midvastus surgical approach. Quadriceps voluntary activation was assessed before surgery, and at 3 months and 6 months following surgery. All patients underwent 10 days of inpatient rehabilitation and an additional 4 weeks of outpatient therapy (though not described in the report). There was no main effect of time or surgical approach, and quadriceps voluntary activation levels were well below normal at all test points. Some others, however, report some limited activation improvements over time 6,78 ; however, even years after TKA, activation of the quadriceps muscle is still significantly lower than for age-matched healthy controls. 6 Poor quadriceps activation is a rehabilitation concern because it may blunt the potential effectiveness of voluntary exercise that relates to improving physical function. Quadriceps activation failure appears to act as a moderator between quadriceps strength and physical function in patients with knee OA. That is, physical function may be more limited in those people with quadriceps weakness and a higher degree of activation failure. 21 Sarcopenia, the progressive loss of muscle mass with aging, is a fundamental contributor to disability in the elderly population. 83 The quadriceps muscle activation failure present in patients with OA may be contributing to muscle atrophy, as neuromuscular inhibition prevents full muscle activation and potentially blunts the stimulus necessary to maintain muscle mass. 31 Clinicians sense both activation failure and atrophy occur in those with TKA, though there are very few reports which have assessed muscle size changes prior to or following TKA. Quadriceps atrophy of 5% to 20% has been reported in the first month after surgery compared to preoperative values. 54,62,67 A recent report utilizing magnetic resonance imaging (MRI) assessments on patients who are awaiting surgery describes a mean quadriceps cross-sectional area (CSA) that is quite small at 42.3 cm 2. Additionally, a 10% decrease in muscle size 1 month following TKA (38.2 cm 2 ), compared to the preoperative values, has been reported. 54 When including quadriceps atrophy into the regression model with activation failure 85% of the change in quadriceps strength in the first month after surgery is explained, though the contribution of the voluntary activation was nearly twice the relative contribution of the maximal cross-sectional area in the regression equation. 54 The atrophy associated with TKA may be a conservative estimate of muscle loss, considering the comparisons that have been made to the uninvolved or the preoperative values. As noted earlier, the assumption that the uninvolved extremity is normal may not be a valid comparison in individuals with a history of OA. The maximal quadriceps CSA of patients between the ages of 41 to 75 years with a history of OA is 46.1 to 49.5 cm 2. 24,25 This is considerably less than a comparative group between the ages of 65 and 81 years, with a maximal CSA of 63.5 to 68.1 cm 2. 17,22 In summary, most individuals with a TKA exhibit small quadriceps CSA values that are consistent with long-term OA-induced weakness. As well, it is still unclear whether muscle strength and atrophy can return to age-matched normal values with postoperative rehabilitation interventions. journal of orthopaedic & sports physical therapy volume 38 number 5 may

6 tion in their physical function 1 year after surgery. 13 Functional outcome scores reported via questionnaires indicate an improvement in quality of life following surgery, but actual physical performance measures and the individual s perception of functional ability remain worse than the age-matched healthy population. 18,59 Individuals 1 year after a TKA surgery perceived their functional ability to be approximately 80% of a group of similar age. In another self-report study only 50% of the TKA recipients considered their knee function normal compared to their healthy peers. 59 Likewise, quadriceps weakness does not correlate well with patient perceptions of function. 52 Self-report scores of physical function in this population tend to correspond to what patients experience (like pain or perceived exertion) when performing activities, rather than their actual ability to complete an activity. 81,84 Improvement in self-report physical function is often most strongly associated with improvements in pain. 81 While quadriceps weakness may have a limited association with perceived functional ability, it tends to have a strong relationship with performance. 52 Quadriceps weakness in older adults has been associated with an increased fall risk, 73 decreased gait speed, 5,37,55,60,85 and impaired stair-climbing ability. 85 Like with other elderly patient cohorts, strength is an important predictor of functional abilities 32,39 in patients who have TKA. 53 Once more, bodily pain scores do not seem to limit functional performance from 1 month to 6 months after surgery. 52 Even though knee range of motion (ROM) is also considered to be important in early phases of therapy for enhancing functional performance, there is little evidence that function is related to knee ROM. 50,52 Rehabilitation following a TKA should still be directed towards pain control and improving knee ROM, but a focus on exercises to address quadriceps muscle impairments appears necessary to achieve the best functional abilities. 8,52,79 The loss of quadriceps muscle strength seems to be an inevitable consequence for people who have TKA surgery; hence, some have suggested the need for a more aggressive and long-term postoperative rehabilitation approach. 5,72 Quadriceps muscle impairments and corresponding functional limitations have been addressed in physical therapy regimens, but the outcomes to date have generally been suboptimal and individuals with TKA continue to perform below age- and gender-matched controls. 18,85 The reports of both preoperative and postoperative TKA rehabilitation outcomes suggest further modifications to the physical interventions that are needed to maximize muscle structure and functional response post surgery. However, further research, specifically randomized controlled trials, is warranted to investigate the effectiveness of strengthening exercises and manual physical therapy in individuals after a TKA. Physical countermeasures have been successful in improving knee pain, strength, and joint stability in those with knee OA who were not yet planning to have a TKA. 11,12,20 For those who go on to a TKA, preoperative quadriceps strength is a strong predictor of functional performance 1 year after surgery. 53 Furthermore, individuals with more extensive signs of OA have more quadriceps weakness. 73 If quadriceps weakness could be addressed prior to TKA surgery, then perhaps patients might experience a better overall functional level. Unfortunately, there is little documented success in improving the preoperative status in those planning a TKA. 19,20,82 Physical therapy interventions prior to TKA have focused on strengthening, aerobic conditioning, and educational programs. D Lima et al 14 compared the effects of preoperative upper and lower extremity strength training, general cardiovascular conditioning exercises, and no intervention (control group) in individuals before and after TKA (10 subjects per group). No significant differences were observed in the 3 groups at any of the postoperative evaluations. In another study conducted by Rodgers et al, patients who underwent 6 weeks of preoperative physical therapy showed no significant change in Hospital for Special Surgery Knee Rating (HSS) scores, knee ROM, isokinetic knee extension strength, and walking speed prior to surgery. 67 Beaupre et al 4 addressed the combined effect of preoperative strengthening exercise and education in 131 subjects scheduled for TKA. The outcome measures included gait training with an assistive device, bed mobility, and transfer training for functional recovery, and the Health-Related Quality of Life (HRQOL) questionnaire. The authors reported no significant differences in ROM, quadriceps and hamstring strength, function, or HRQOL score when compared to a control group 1 year after TKA. Finally, Rooks et al 68 found no significant improvements in self-reported function or performance measures in those who underwent preoperative exercise training compared to those who did not (22 patients assigned per group). Considering these findings, it may be that quadriceps weakness and functional limitations are recalcitrant in those about to receive a knee replacement; however, starting quadriceps strengthening earlier (ie, in the beginning stages of OA) may be the best approach. 53 There is a dearth of available evidence for determining the best possible postoperative rehabilitation intervention, though a limited number of reports suggest that improvements in ROM and strength, a lowered pain level, and improvements in independence with activities of daily living have resulted from such interventions. The authors of a recent randomized controlled trial comparing a 250 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy

7 supervised home rehabilitation exercise program to standard-care control group reported that individuals with TKA who received 12 supervised rehabilitation treatment sessions starting 2 months after surgery walked longer distances at 1 year after surgery compared to the control group, and the distance walked in 6 minutes was within 1 standard deviation of a group of healthy, age-matched individuals. 58 The treatment group showed an accelerated symptom recovery with less pain, stiffness, and difficulty performing daily activities compared to the standard-care group, as reported on the WOMAC and SF-36 at 6 months after surgery; but no significant differences were noted at 1 year postsurgery. A description and comparison of published A Comparison of Therapeutic Exercise Rehabilitation Approaches Following TKA 52,78 58 Start of therapy 1 d postoperative 3.5 wk postoperative 8 wk postoperative Frequency 2 times/d 3 times/wk 1-2 times/wk Number of visits (duration) 16 (8 d) 18 (6 wk) 12 (8 wk) NMES* Yes (6 wk) Yes* No Bike 5-10 min min 5-20 min Core exercises Quadriceps sets X X X Hamstring sets X X Straight-leg raise X X X Hip abduction X X Standing terminal extension X X Step-ups/-downs X X AROM/AAROM X X X Seated knee extension X Wall squats/standing squats X X Standing hamstring curl X X Lunges X Walking X X Non weight-bearing ROM X X X Ankle pumps X Sit-to-stand X Walking backward, marching, side step X Abbreviations: AAROM, active assistive range of motion; AROM, active range of motion; NMES, neuromuscular electrical stimulation; ROM, range of motion; TKA, total knee arthroplasty. * NMES parameters: 2500-Hz triangular-wave alternating current (AC), 12-s on-time, 80-s off-time, 2- to 3-s ramp-up time, knee flexed to 60, 10 isometric contractions, dose set to maximally tolerated by the patient, large ( cm) self-adhesive electrodes placed on motor points of the quadriceps femoris muscle. postoperative therapy protocols is provided in. A longitudinal study with a more progressive and intense rehabilitation program instituted earlier after TKA (3-4 weeks postoperatively) and designed specifically to address the functional impairments following a TKA has been repeatedly reported by Mizner and colleagues at the University of Delaware. 52,78 Their protocol consisted of 3 days of inpatient physical therapy, followed by 2 to 3 weeks of home physical therapy visits. At approximately 4 weeks after surgery, the patients with TKA began 6 weeks (2 to 3 times per week) of outpatient rehabilitation. Progressive, high-intensity volitional exercises were used to increase lower musculature extremity strength and improve functional ability in 40 individuals who completed this protocol ( ). At 1 month postsurgery, before treatment was initiated, knee ROM, quadriceps strength, and performance on the timed up and go (TUG) and stair climb test (SCT) were lower than they were at presurgery. The TKA recipients quadriceps strength decreased 62% from the preoperative value at the first month postsurgery. Following 6 weeks of rehabilitation, quadriceps strength improved significantly at each following assessment (2, 3, and 6 months postsurgery). There was also a 21% improvement in the TUG and a 40% improvement in the SCT from the preoperative test to 6 months after surgery. Finally, quadriceps strength was correlated with functional performance measures at all testing sessions and, as quadriceps strength improved, there was an enhancement in functional performance. This study clearly demonstrates that the muscle impairments and functional limitations can be reversed following a TKA. 52 There is also some evidence that the addition of neuromuscular electrical stimulation (NMES) to a physical therapy protocol could enhance the speed and ultimate recovery of quadriceps strength after TKA. In 2 case report series from the same group, the addition of high-intensity NMES to the quadriceps muscle produced strength gains that exceeded previously published outcomes 40,78 (NMES specifications described in ). The data were also suggestive of a positive dose-response relationship for NMES. Those patients who achieved a higher percentage of their knee extension maximal voluntary isometric contraction torque with NMES contractions had greater gains in strength. 78 These results suggest that NMES early after TKA may help resolve quadriceps activation failure and mitigate quadriceps muscle weakness. When considering the low quadriceps activation in this patient population early after surgery, the addition of NMES to augment volitional strengthening exercises could be a useful adjunct to reha- journal of orthopaedic & sports physical therapy volume 38 number 5 may

8 bilitation, especially for those people who are very weak. The addition of NMES even earlier than 4 weeks may also be beneficial. A randomized control study by Avramidis et al 3 investigated the effect of 4 hours per day of NMES (40 Hz, 300 μs) to the vastus medialis, commencing on postoperative day 2 and continuing for 6 weeks following surgery. This resulted in improved walking speed, though no changes were noted in the HSS or in an index of physiological cost. 3 A recent case report also describes the use of NMES, initiated on postoperative day 2 for a 6-week period, and reported strength gains in the first month after surgery compared to preoperative values. 51 In summary, outpatient rehabilitation after a TKA seems to be superior to no intervention at all. These studies suggest that muscle impairments and functional limitations can be reversed following a TKA. But additional research is necessary to determine the optimal mode, intensity, and duration of physical therapy needed to mitigate the muscle impairments and related functional limitations following a TKA. The recommendations and clinical guidelines described below are derived from the best available evidence, but additional research, specifically randomized controlled trials, is needed to optimize short- and long-term outcomes for individuals after a TKA. Nevertheless, recipients of TKA should respond favorably to similar therapeutic exercise guidelines as suggested by the American College of Sports Medicine (ACSM) for older individuals. 47 That is, progressive resistive training of major muscle groups (especially of the lower extremities) should be performed 2 to 3 times per week and aerobic training 3 times per week for 30 to 40 minutes. 38 The aerobic training for those with a TKA, however, should include walking on flat ground initially, adding hills, and 1999 Knee Society Survey 28 Aerobics (low impact) Square dancing Bicycling (stationary) Walking Bowling Golf Croquet Horseshoes Ballroom dancing Shooting Jazz dancing Shuffleboard Swimming Horseback riding Bicycling (road) Skiing (cross country) Canoeing Skiing (stationary) Hiking Tennis (doubles) Rowing Weight machines Speed walking Racquetball Football Squash Gymnastics Rock climbing Lacrosse Soccer Hockey Singles tennis Basketball Volleyball Jogging Handball Fencing Downhill skiing Roller blade/inline skating Weight lifting negotiating stairs. Higher-level aerobic exercises that minimize impact to the knee, such as swimming, cycling, water aerobics, and power walking, are also recommended. Recreational activities with high joint loads, such as skiing, tennis, and hiking, should be performed with caution and only occasionally. TKA recipients are strongly cautioned to avoid even the lowest-level impact recreational and athletic activities until their quadriceps and hamstring muscles are rehabilitated sufficiently. 28 Specific recommendations derived from the 1999 Knee Society Survey 28 have been used to develop a consensus recommendation for athletics and sports participation for those with a TKA ( ). Despite these guidelines, many TKA recipients still experience significant difficulty in performing activities that require higher-level mobility skills commensurate with recreational activities. 18,59 Therapeutic exercise guidelines following a TKA are traditionally focused on the control of pain and swelling, while improving ROM and functional mobility. More progressive, high-intensity exercises may be necessary to address lower extremity muscle size, activation and strength deficits, along with functional mobility early following surgery. The use of NMES along with an exercise program has demonstrated improved quadriceps strength and activation and is recommended early in a rehabilitation program. Resistance training (60% of the 1-repetition maximum) has been demonstrated to induce increases in strength in the elderly. 16 Therefore, it may be necessary to increase the lower extremity strength training to at least that level of intensity for 1 to 3 sets of 10 to 20 repetitions to overcome the recalcitrant muscle impairments which may be present 6 months to 1 year following TKA. The 252 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy

9 provides specific guidelines relative to a progressive rehabilitative program for those following a TKA. These recommendations are used to address the pertinent muscle impairments in addition to enhancing mobility. The protocols mentioned by Moffet and colleagues 58 and the investigations from Snyder-Mackler s laboratory at the University of Delaware 40,55,78 are combined with the ACSM guidelines into 4 phases and the timelines are a guide for progression into the next phase. Modifications to this program are instituted immediately if adverse knee joint reactions (eg, pain, swelling) occur. Decreasing the intensity, frequency, and duration of the resistance exercise typically resolves any adverse knee response. In phase I following a TKA, patients receive home health or outpatient physical therapy 2 to 3 times per week for 2 to 3 weeks after inpatient discharge. The emphasis of physical therapy in this phase is on edema management, improving ROM, starting a strengthening program, and improving functional independence. At approximately 3 to 4 weeks postsurgery, or when goals are met, the patients start phase II, which consists of outpatient physical therapy 2 to 3 times per week for 4 to 6 weeks. Augmentation of the quadriceps muscle s activation following TKA should be emphasized early in this rehabilitation phase to help restore quadriceps muscle strength. Physical therapy treatments should employ the concepts of progressive high-intensity volitional exercises with NMES to increase strength and quadriceps muscle activation. 52,58,78 At 10 to 12 weeks postoperative or when the criteria for progression are met, such as ROM from 5 or less to 110 or greater, minimal pain and edema, and voluntary quadriceps muscle control, patients progress to phase III of the rehabilitation program. Phase III includes a semi-independent period of 4 to 8 inclinic visits over 3 to 4 weeks, with a goal to improve strength and progress to an independent phase (phase IV), with clinical follow-up visits for another 8 weeks. In addition to a warm-up and functional endurance exercises, this program places an emphasis on strengthening resistance exercises for the lower extremity. In an attempt to mitigate the muscle impairments, progressive, moderately highresistance exercises are used. Most often individuals with TKA can increase the intensity of exercise after 3 sets of 10 repetitions are completed correctly without undue fatigue. Muscle impairments that exist following a TKA may persist for years. Improving quadriceps strength may mitigate these impairments and result in improved functional outcomes. An emphasis on muscle weakness countermeasures, like resistance exercises and NMES, is needed. Further research is required to determine the optimal exercise prescription that can safely augment the return to near-normal levels of activity and function for individuals who had TKA surgery. NIH Consensus Statement on total knee replacement December 8-10, J Bone Joint Surg Am. 2004;86-A: American Academy of Orthopaedic Surgeons. Arthroplasty and Total Joint Replacement Procedures: Available at: http// org/wordhtml/research/stats/arthroplasty_recent.htm. Accessed Avramidis K, Strike PW, Taylor PN, Swain ID. Effectiveness of electric stimulation of the vastus medialis muscle in the rehabilitation of patients after total knee arthroplasty. Arch Phys Med Rehabil. 2003;84: Beaupre LA, Lier D, Davies DM, Johnston DB. The effect of a preoperative exercise and education program on functional recovery, health related quality of life, and health service utilization following primary total knee arthroplasty. J Rheumatol. 2004;31: Berman AT, Bosacco SJ, Israelite C. Evaluation of total knee arthroplasty using isokinetic testing. Clin Orthop Relat Res. 1991; Berth A, Urbach D, Awiszus F. Improvement of voluntary quadriceps muscle activation after total knee arthroplasty. Arch Phys Med Rehabil. 2002;83: Berth A, Urbach D, Neumann W, Awiszus F. Strength and voluntary activation of quadriceps femoris muscle in total knee arthroplasty with midvastus and subvastus approaches. J Arthroplasty. 2007;22: org/ /j.arth Brander VA, Mullarkey CF, Stulberg SD. Rehabilitation After Total Joint Replacement for Osteoarthritis: An Evidence-Based Approach. Philadelphia, PA: Hanley & Belfus, Inc; Brandt KD, Heilman DK, Slemenda C, et al. A comparison of lower extremity muscle strength, obesity, and depression scores in elderly subjects with knee pain with and without radiographic evidence of knee osteoarthritis. J Rheumatol. 2000;27: Chmielewski TL, Stackhouse S, Axe MJ, Snyder- Mackler L. A prospective analysis of incidence and severity of quadriceps inhibition in a consecutive sample of 100 patients with complete acute anterior cruciate ligament rupture. J Orthop Res. 2004;22: org/ /j.orthres Deyle GD, Allison SC, Matekel RL, et al. Physical therapy treatment effectiveness for osteoarthritis of the knee: a randomized comparison of supervised clinical exercise and manual therapy procedures versus a home exercise program. Phys Ther. 2005;85: Deyle GD, Henderson NE, Matekel RL, Ryder MG, Garber MB, Allison SC. Effectiveness of manual physical therapy and exercise in osteoarthritis of the knee. A randomized, controlled trial. Ann Intern Med. 2000;132: Dickstein R, Heffes Y, Shabtai EI, Markowitz E. Total knee arthroplasty in the elderly: patients self-appraisal 6 and 12 months postoperatively. Gerontology. 1998;44: D Lima DD, Colwell CW, Jr., Morris BA, Hardwick ME, Kozin F. The effect of preoperative exercise on total knee replacement outcomes. Clin Orthop Relat Res. 1996; Ettinger WH, Jr., Afable RF. Physical disability from knee osteoarthritis: the role of exercise as an intervention. Med Sci Sports Exerc. 1994;26: Evans WJ. Exercise training guidelines for the elderly. Med Sci Sports Exerc. 1999;31: Ferri A, Scaglioni G, Pousson M, Capodaglio P, Van Hoecke J, Narici MV. Strength and power changes of the human plantar flexors and knee extensors in response to resistance training in old age. Acta Physiol Scand. 2003;177: Finch E, Walsh M, Thomas SG, Woodhouse LJ. Functional ability perceived by individuals following total knee arthroplasty compared to agematched individuals without knee disability. J Orthop Sport Phys Ther. 1998;27: Fitzgerald GK. Therapeutic exercise for knee osteoarthritis: considering factors that may influence outcome. Eura Medicophys. 2005;41: Fitzgerald GK, Oatis C. Role of physical therapy in management of knee osteoarthritis. Curr Opin Rheumatol. 2004;16: Fitzgerald JD, Orav EJ, Lee TH, et al. 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10 quality of life during the 12 months following joint replacement surgery. Arthritis Rheum. 2004;51: art Frontera WR, Hughes VA, Fielding RA, Fiatarone MA, Evans WJ, Roubenoff R. Aging of skeletal muscle: a 12-yr longitudinal study. J Appl Physiol. 2000;88: Gapeyeva H, Buht N, Peterson K, Ereline J, Haviko T, Paasuke M. Quadriceps femoris muscle voluntary isometric force production and relaxation characteristics before and 6 months after unilateral total knee arthroplasty in women. Knee Surg Sports Traumatol Arthrosc. 2007;15: s y Gur H, Cakin N, Akova B, Okay E, Kucukoglu S. Concentric versus combined concentriceccentric isokinetic training: effects on functional capacity and symptoms in patients with osteoarthrosis of the knee. Arch Phys Med Rehabil. 2002;83: Gur H, Cakin N. Muscle mass, isokinetic torque, and functional capacity in women with osteoarthritis of the knee. Arch Phys Med Rehabil. 2003;84: Hartley RC, Barton-Hanson NG, Finley R, Parkinson RW. Early patient outcomes after primary and revision total knee arthroplasty. A prospective study. J Bone Joint Surg Br. 2002;84: Hassan BS, Mockett S, Doherty M. Static postural sway, proprioception, and maximal voluntary quadriceps contraction in patients with knee osteoarthritis and normal control subjects. Ann Rheum Dis. 2001;60: Healy WL, Iorio R, Lemos MJ. Athletic activity after total knee arthroplasty. Clin Orthop Relat Res. 2000; Huang CH, Cheng CK, Lee YT, Lee KS. Muscle strength after successful total knee replacement: a 6- to 13-year followup. Clin Orthop Relat Res. 1996; Hurley MV, Jones DW, Newham DJ. Arthrogenic quadriceps inhibition and rehabilitation of patients with extensive traumatic knee injuries. Clin Sci (Lond). 1994;86: Hurley MV, Newham DJ. The influence of arthrogenous muscle inhibition on quadriceps rehabilitation of patients with early, unilateral osteoarthritic knees. Br J Rheumatol. 1993;32: Hurley MV, Scott DL. Improvements in quadriceps sensorimotor function and disability of patients with knee osteoarthritis following a clinically practicable exercise regime. Br J Rheumatol. 1998;37: Jones CA, Voaklander DC, Johnston DW, Suarez-Almazor ME. Health related quality of life outcomes after total hip and knee arthroplasties in a community based population. J Rheumatol. 2000;27: Jones DL, Westby MD, Greidanus N, et al. Update on hip and knee arthroplasty: current state of evidence. Arthritis Rheum. 2005;53: Kane RL, Saleh KJ, Wilt TJ, Bershadsky B. The functional outcomes of total knee arthroplasty. J Bone Joint Surg Am. 2005;87: Kent-Braun JA, Le Blanc R. Quantitation of central activation failure during maximal voluntary contractions in humans. Muscle Nerve. 1996;19: (SICI) (199607)19:7<861::AID- MUS8>3.0.CO;2-7 Kroll MA, Otis JC, Sculco TP, et al. The relationship of stride characteristics to pain before and after total knee arthroplasty. Clin Orthop Relat Res. 1989; Kuster MS. Exercise recommendations after total joint replacement: a review of the current literature and proposal of scientifically based guidelines. Sports Med. 2002;32: Landers KA, Hunter GR, Wetzstein CJ, Bamman MM, Weinsier RL. The interrelationship among muscle mass, strength, and the ability to perform physical tasks of daily living in younger and older women. J Gerontol A Biol Sci Med Sci. 2001;56:B Lewek M, Stevens J, Snyder-Mackler L. The use of electrical stimulation to increase quadriceps femoris muscle force in an elderly patient following a total knee arthroplasty. Phys Ther. 2001;81: Ling SM, Xue QL, Simonsick EM, et al. Transitions to mobility difficulty associated with lower extremity osteoarthritis in high functioning older women: longitudinal data from the Women s Health and Aging Study II. Arthritis Rheum. 2006;55: art Lorentzen JS, Petersen MM, Brot C, Madsen OR. Early changes in muscle strength after total knee arthroplasty. A 6-month follow-up of 30 knees. Acta Orthop Scand. 1999;70: Mahomed NN, Liang MH, Cook EF, et al. The importance of patient expectations in predicting functional outcomes after total joint arthroplasty. J Rheumatol. 2002;29: Manal TJ, Snyder-Mackler L. Failure of voluntary activation of the quadriceps femoris muscle after patellar contusion. J Orthop Sports Phys Ther. 2000;30: ; discussion March LM, Cross MJ, Lapsley H, et al. Outcomes after hip or knee replacement surgery for osteoarthritis. A prospective cohort study comparing patients quality of life before and after surgery with age-related population norms. Med J Aust. 1999;171: Martin SD, Scott RD, Thornhill TS. Current concepts of total knee arthroplasty. J Orthop Sports Phys Ther. 1998;28: Mazzeo RS, Cavanagh P, Evans WJ, et al. American College of Sports Medicine Position Stand. Exercise and physical activity for older adults. Med Sci Sports Exerc. 1998;30: McMahon M, Block JA. The risk of contralateral total knee arthroplasty after knee replacement for osteoarthritis. J Rheumatol. 2003;30: Miller M, Flansbjer UB, Downham D, Lexell J. Superimposed electrical stimulation: assessment of voluntary activation and perceived discomfort in healthy, moderately active older and younger women and men. Am J Phys Med Rehabil. 2006;85: org/ /01.phm Miner AL, Lingard EA, Wright EA, Sledge CB, Katz JN. Knee range of motion after total knee arthroplasty: how important is this as an outcome measure? J Arthroplasty. 2003;18: arth Mintken PE, Carpenter KJ, Eckhoff D, Kohrt WM, Stevens JE. Early neuromuscular electrical stimulation to optimize quadriceps muscle function following total knee arthroplasty: a case report. J Orthop Sports Phys Ther. 2007;37: jospt Mizner RL, Petterson SC, Snyder-Mackler L. Quadriceps strength and the time course of functional recovery after total knee arthroplasty. J Orthop Sports Phys Ther. 2005;35: Mizner RL, Petterson SC, Stevens JE, Axe MJ, Snyder-Mackler L. Preoperative quadriceps strength predicts functional ability one year after total knee arthroplasty. J Rheumatol. 2005;32: Mizner RL, Petterson SC, Stevens JE, Vandenborne K, Snyder-Mackler L. Early quadriceps strength loss after total knee arthroplasty. The contributions of muscle atrophy and failure of voluntary muscle activation. J Bone Joint Surg Am. 2005;87: org/ /jbjs.d Mizner RL, Snyder-Mackler L. Altered loading during walking and sit-to-stand is affected by quadriceps weakness after total knee arthroplasty. J Orthop Res. 2005;23: Mizner RL, Snyder-Mackler L. Patients perceptions do not match functional performance or clinical presentation after total knee arthroplasty. 10th World Congress on Osteoarthritis. Prague, Czech Republic: Mizner RL, Stevens JE, Snyder-Mackler L. Voluntary activation and decreased force production of the quadriceps femoris muscle after total knee arthroplasty. Phys Ther. 2003;83: Moffet H, Collet JP, Shapiro SH, Paradis G, Marquis F, Roy L. Effectiveness of intensive rehabilitation on functional ability and quality of life after first total knee arthroplasty: A single-blind randomized controlled trial. Arch Phys Med Rehabil. 2004;85: Noble PC, Gordon MJ, Weiss JM, Reddix RN, Conditt MA, Mathis KB. Does total knee replacement restore normal knee function? Clin Orthop Relat Res. 2005; Ouellet D, Moffet H. Locomotor deficits before and two months after knee arthroplasty. Ar- 254 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy

11 thritis Rheum. 2002;47: org/ /art Parent E, Moffet H. Comparative responsiveness of locomotor tests and questionnaires used to follow early recovery after total knee arthroplasty. Arch Phys Med Rehabil. 2002;83: Perhonen M, Komi P, Hakkinen K, von Bonsdorff H, Partio E. Strength training and neuromuscular function in elderly people with total knee endoprosthesis. Scand J Med Sci Sports. 1992;2: Peterson SC, Mizner RL, Snyder-Mackler L. Quadriceps Femoris Muscle Recovery After Total Knee Arthroplasty. 9th World Congress on Osteoarthritis. Chicago, IL: Ritter MA, Albohm MJ, Keating EM, Faris PM, Meding JB. Comparative outcomes of total joint arthroplasty. J Arthroplasty. 1995;10: Ritter MA, Carr KD, Keating EM, Faris PM. Longterm outcomes of contralateral knees after unilateral total knee arthroplasty for osteoarthritis. J Arthroplasty. 1994;9: Ritter MA, Thong AE, Davis KE, Berend ME, Meding JB, Faris PM. Long-term deterioration of joint evaluation scores. J Bone Joint Surg Br. 2004;86: Rodgers JA, Garvin KL, Walker CW, Morford D, Urban J, Bedard J. Preoperative physical therapy in primary total knee arthroplasty. J Arthroplasty. 1998;13: Rooks DS, Huang J, Bierbaum BE, et al. Effect of preoperative exercise on measures of functional status in men and women undergoing total hip and knee arthroplasty. Arthritis Rheum. 2006;55: art Roos EM, Toksvig-Larsen S. Knee injury and Osteoarthritis Outcome Score (KOOS) - validation and comparison to the WOMAC in total knee replacement. Health Qual Life Outcomes. 2003;1:17. org/ / Rossi MD, Brown LE, Whitehurst M. Early strength response of the knee extensors during eight weeks of resistive training after unilateral total knee arthroplasty. J Strength Cond Res. 2005;19: org/ /r Rossi MD, Brown LE, Whitehurst M. Knee extensor and flexor torque characteristics before and after unilateral total knee arthroplasty. Am J Phys Med Rehabil. 2006;85: dx.doi.org/ /01.phm a5 Silva M, Shepherd EF, Jackson WO, Pratt JA, McClung CD, Schmalzried TP. Knee strength after total knee arthroplasty. J Arthroplasty. 2003;18: Slemenda C, Brandt KD, Heilman DK, et al. Quadriceps weakness and osteoarthritis of the knee. Ann Intern Med. 1997;127: Slemenda C, Heilman DK, Brandt KD, et al. Reduced quadriceps strength relative to body weight: a risk factor for knee osteoarthritis in women? Arthritis Rheum. 1998;41: Snyder-Mackler L, De Luca PF, Williams PR, Eastlack ME, Bartolozzi AR, 3rd. Reflex inhibition of the quadriceps femoris muscle after injury or reconstruction of the anterior cruciate ligament. J Bone Joint Surg Am. 1994;76: Stackhouse SK, Dean JC, Lee SC, Binder- MacLeod SA. Measurement of central activation failure of the quadriceps femoris in healthy adults. Muscle Nerve. 2000;23: MUS6>3.0.CO;2-B Stackhouse SK, Stevens JE, Lee SC, Pearce KM, Snyder-Mackler L, Binder-Macleod SA. Maximum voluntary activation in nonfatigued and fatigued muscle of young and elderly individuals. Phys Ther. 2001;81: Stevens JE, Mizner RL, Snyder-Mackler L. Neuromuscular electrical stimulation for quadriceps muscle strengthening after bilateral total knee arthroplasty: a case series. J Orthop Sports Phys Ther. 2004;34: Stevens JE, Mizner RL, Snyder-Mackler L. Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis. J Orthop Res. 2003;21: dx.doi.org/ /s (03) Stickles B, Phillips L, Brox WT, Owens B, Lanzer WL. Defining the relationship between obesity and total joint arthroplasty. Obes Res. 2001;9: Stratford PW, Kennedy DM. Performance measures were necessary to obtain a complete picture of osteoarthritic patients. J Clin Epidemiol. 2006;59: jclinepi van Baar ME, Assendelft WJ, Dekker J, Oostendorp RA, Bijlsma JW. Effectiveness of exercise therapy in patients with osteoarthritis of the hip or knee: a systematic review of randomized clinical trials. Arthritis Rheum. 1999;42: org/ / (199907)42:7<1361::aid- ANR9>3.0.CO;2-9 Volpi E, Nazemi R, Fujita S. Muscle tissue changes with aging. Curr Opin Clin Nutr Metab Care. 2004;7: Walker DJ, Heslop PS, Chandler C, Pinder IM. Measured ambulation and self-reported health status following total joint replacement for the osteoarthritic knee. Rheumatology (Oxford). 2002;41: Walsh M, Woodhouse LJ, Thomas SG, Finch E. Physical impairments and functional limitations: a comparison of individuals 1 year after total knee arthroplasty with control subjects. Phys Ther. Goals: 1. Increase range of motion (ROM) 2. Decrease edema and pain 3. Gait training 4. Independence with activities of daily living (ADLs) Exercises: 1. Seated or supine knee active range of motion (AROM) 2. Alternated ankle dorsiflexion and plantar flexion 3. Quadriceps sets 4. Straight-leg raise 5. Hamstring sets 6. Standing leg curls 7. Seated knee extension 8. Supported single standing for balance 9. Repeated sit-to-stand transfer training 10. Ambulating with appropriate assistive device Modalities: 1. Ice 2-3 times per d, with lower extremity elevated for min journal of orthopaedic & sports physical therapy volume 38 number 5 may

12 Criteria for progression to exclusively outpatient physical therapy: a. AROM approaching 90 of knee flexion b. Minimal pain/swelling c. Independence in mobility in and out of the home Warm-up (15-20 min): 1. Exercise bike (10-15 min), start with forward and backward pedaling with no resistance until there s enough knee ROM for a full revolution. Seat height may be lowered for progression of ROM 2. Seated or supine knee AROM (flexion and extension) 3. Alternated ankle dorsiflexion and plantar flexion 4. Passive knee extension stretch 5. Patellar and knee mobilizations Specific strengthening (10-15 min), 1-3 sets of 10 repetitions: 1. Neuromuscular electrical stimulation (NMES) to augment quadriceps muscle activation. NMES parameters: 2500-Hz triangular-wave alternating current, 12-s on-time, 80-s off-time, 2- to 3-s ramp-up time, knee flexed to 60, 10 isometric contractions, dose set to maximally tolerated by the patient, large ( cm) self-adhesive electrodes placed on the motor points of the quadriceps femoris muscle 2. Quadriceps sets 3. Straight-leg raises (assistance as needed, goal to perform without a knee extension lag) 4. Hip abduction (side lying) 5. Standing leg curls 6. Seated knee extension 7. Standing terminal knee extension from 45 to 0 Functional exercises (10-15 min): 1. Step-ups, 5-15 cm, or climbing a flight of stairs wall slides or sit-to-stands 3. Walking backward, side step, march, or crossover steps 4. Walking through an obstacle course 5. Gait training emphasis on heel strike and push-off at toe-off Endurance exercises (5-20 min): 1. Walking 2. Stationary cycle Cool-down (10 min): 1. Ice and compression as needed 2. Gentle stretching and ROM Criteria for progression: a. Voluntary quadriceps muscle control or 0 knee extension lag b. AROM 0 to greater than 105 of knee flexion c. Minimal to no pain and swelling Exercise progression: a. Exercises are to be progressed once the patient can complete 3 sets of 10 reps of the exercise correctly and feels maximally fatigued b. Add 0.2- to 1.5-kg weights to the exercises c. Increase step height if showing good concentric/eccentric control d. Increase wall slides to 60 and to 90 Exercises: 1. Continue all exercises in phase I as a home exercise program or a gym membership Warm-up (15-20 min): 1. Seated or supine knee AROM (flexion and extension) 2. Alternated ankle dorsiflexion and plantar flexion 3. Passive knee extension and hamstring stretch 4. Exercise bike or treadmill walking (perceived exertion should be light) Strengthening (20-30 min, 1-3 sets of reps of any of the following): 1. Leg press varying working ROM* 2. Leg extension: ROM, 90-0 or for extension* 3. Standing or sitting leg curls* 4. Standing heel raises* 5. 4-way hip machine or (rubber band or ankle weights for resisted hip ROM)* 6. Sit-to-stand free weights in hands 7. Weight-bearing exercises with emphasis on eccentric control 8. Upper extremity strength training optional *Use a 5- or 10-repetition maximum to determine 60%-70% resistance of 1-repetition maximum *Machine weights Functional exercises (10-15 min): 1. Step-ups 5-15 cm or climbing a flight of stairs to 90 wall slides or sit-to-stands, hold 5-10 s 3. Walking backward, side step, march, or crossover steps Endurance exercises (5-20 min, alternate between walking and biking): 1. Walking, change speed and incline 2. Biking Criteria for progression: Exercises are to be progressed once the patient can complete 3 sets of 10 reps of the exercise correctly and feels maximally fatigued Exercise progression: a. Reassess 65%-70% of maximal effort biweekly to determine progression of resistance b. Increase step height if showing good concentric/eccentric control c. Increase wall slides to 60 and to 90 Exercises (continue all exercises, 1-3 sets at reps, as a home program or a gym membership 2-3 times/wk) 256 may 2008 volume 38 number 5 journal of orthopaedic & sports physical therapy