In 2000, people are living longer than ever, and elderly Americans are staying active. Golf, tennis, power walking, swimming, sailing, and many other sports are popular among senior citizens. As Americans age, the prevalence of arthritic joints is increasing, and when a painful arthritic knee limits their ability to play sports, Americans are choosing knee replacement operations to relieve pain and improve function. 2,8,16,17 Total knee arthroplasty has proven to be a predictable and successful treatment for painful arthritic knees. The prevalence of total knee arthroplasty paid for by Medicare in the United States was 186,644 operations in 1998. 16
The results of total knee arthroplasty have been studied with pain scores, clinical scores, physical examinations, radiography, activity measures, validated outcome instruments, and economic assessments. 2–4,6,7,9,10,15,18 Knee replacement has been documented to relieve pain, improve function, increase social mobility and interaction, and contribute to psychologic well being. 21 Furthermore, knee replacement is a cost-effective medical intervention, which is associated with significant improvements in quality of life. 5,21 At the turn of the century, 90% or more of patients who have knee replacement can expect 10 to 20 years of satisfactory function. 2,4–6,15,18
Indications for knee replacement have expanded during the past decade. During the 1970s and 1980s, knee replacement operations were performed mostly for pain and deformity. The expected benefit from the operation was reduced pain, correction of deformity, and improved function, but pain was the primary reason to consider knee replacement surgery. In 2000, loss of function is the primary reason for knee replacement surgery. Patients are not satisfied with the limitation of function that can accompany an arthritic knee, and patients choose to have knee replacement to improve their function. Increasingly, the desire to improve function includes participation in athletics.
After joint replacement of the lower extremity, patients usually feel better and have increased physical activity. Macnichol et al 13 reported a significant increase in maximal walking speed, walking stride length or cadence, and oxygen consumption after total hip arthroplasty. They also documented a doubling of mean power output during stair climbing after hip replacement. Ries et al 19,20 evaluated cardiovascular fitness after hip and knee replacement. Joint reconstruction and rehabilitation were associated with significant improvements in duration of exercise, maximum workload, peak oxygen consumption, and percentage of predicted maximum oxygen update. They reported that resumption of physical activity after joint replacement was associated with an improvement in cardiovascular fitness, and patients with arthritic joints treated with joint replacement were more fit than patients with arthritic joints who were treated nonoperatively.
One of the secondary indications for total knee arthroplasty is to improve quality of life. Total knee arthroplasty permits patients to exercise, and regular exercise is beneficial for patients with anxiety, depression, obesity, high blood pressure, coronary artery disease, diabetes mellitus, osteoporosis, and low back pain. Exercise also is an integral part of smoking cessation programs. The American College of Sports Medicine 1 reported that aerobic activity three times a week for 20 minutes is associated with improved psychologic and physiologic well being. Knee replacement improves the overall health of patients.
Although more Americans undergoing total knee arthroplasty and more patients with total knee arthroplasty are playing sports, there are no specific guidelines for recreational or athletic activity after knee replacement. Recreational activities are very important to patients undergoing knee replacement, and after surgery patients are encouraged to resume the activities that are important to them. The current review of athletic activity after knee replacement was performed to identify risk factors for patients who wish to participate in sports after total knee arthroplasty and to discuss issues of importance to surgeons and patients regarding athletics after total knee arthroplasty.
Considerations and Risk Factors
Athletic Activity before Surgery
Athletic activity before surgery is a critical factor in recommending athletic activity after knee replacement (Table 1). Patients who have achieved a high level of skill in a sport have the best chance of resuming the activity safely. Patients who have not participated in a specific sport or recreational activity are less likely to achieve high skill levels after knee replacement. Furthermore, patients who have not participated in a specific sport or recreational activity have an increased risk of injury. The best example of this is skiing. Expert skiers can resume their sport safely, especially when they limit themselves to intermediate trails. Skiing probably is not a safe sport for a novice after knee replacement.
Rehabilitation of arthritic joints before total joint arthroplasty has been said to decrease length of hospital stay, improve postoperative physical therapy, and contribute to quicker resumption of activities. 12 In a study by Kovar et al 11 patients with osteoarthritis who were subjected to walking exercise sessions (½ hour three times a week for 8 weeks) improved their 8-minute walking distance. It is not clear whether preoperative rehabilitation, consisting of stretching and strengthening of arthritic joints, contributes to increased proficiency or enjoyment of athletics after joint replacement. It also is not clear whether preoperative rehabilitation reduces risk factors for patients.
One of the most important determinants of whether a patient can participate in athletics after total knee arthroplasty is the technical quality of the operation. The importance of an anatomically and biomechanically correct reconstruction and a competent soft-tissue and muscular reconstruction cannot be underestimated. These factors can be influenced by the surgeon. Total knee arthroplasty requires accurate positioning of implants and careful reconstruction of soft tissues to produce a stable, mobile, functional knee. The technical reconstruction of the arthritic knee is an important predictor of the patient’s ability to participate in athletic activity after knee replacement.
Increased tibiofemoral conformity with minimal constraint has been associated with prosthetic designs with good long-term survivorship. 2 It is not clear whether active patients are better served by posterior cruciate ligament retaining or posterior cruciate ligament sacrificing or substituting implants. Rand and Ilstrup 18 reported a 91% 10-year survival rate for 9200 knee replacements when a cemented, posterior cruciate retaining implant with a metal-backed tibia was used. Colizza et al 6 reported a 96% 11-year survival rate when a cemented, posterior cruciate sacrificing or substituting implant with a metal-backed tibia implant was used.
Limb alignment, joint line reconstruction, and implant design are associated with the quality of result after knee replacement. 2,4,6,18 In a survivorship study of patients undergoing total knee arthroplasty, Rand and Ilstrup 18 reported that patients with tibiofemoral joint lines restored to normal and appropriate patella and implant composite thickness had better function and better durability of the implant. Evaluation of several implant designs regarding polyethylene design and thickness suggests that conforming geometry between femoral condyles and tibial polyethylene can reduce polyethylene wear and increase durability. A minimum 6 mm polyethylene thickness is recommended to reduce polyethylene deformation and wear. 4,7,10
Implant Failure or Fracture
Implant failure was a major consideration for the restriction of activity after joint replacement during the first generation of joint replacement arthroplasty. Stainless steel implants were associated with unacceptable fracture. Since the introduction of CoCr alloys and Ti alloys, implant failure is less common.
Implant Fixation or Loosening
Implant fixation is a critical factor in considering athletic activity after knee replacement surgery. Athletic activity may increase the stress on implant fixation in compression, tension, rotation, and sheer. When patients with total knee arthroplasties choose to participate in sports, they accept more risk of implant loosening than patients with total knee arthroplasties who do not play sports. The quality of surgical reconstruction also is a factor in how the knee implant handles increasing stress with athletics.
Athletic Activity and Bearing Surface Wear
The most significant consideration for patients and orthopaedic surgeons in considering athletic activity after knee replacement is wear at the bearing surface. All bearing surfaces wear. Wear is increased by increasing loading and cycling of the joint. Metal on traditional polyethylene articulations have been successful for 30 years. 2,4–6,18 However, metal-on-polyethylene-bearing surfaces generate polyethylene particles that are associated with osteolysis. Cement particles and metal particles also can induce osteolysis. In knee implants, metal-on-polyethylene wear can occur with the femorotibial insert surface, the tibial insert-tibial baseplate surface, at the femoral box-tibial post surface, and the patellofemoral articulation. The potential for wear at a femoral box-tibial post articulation, with generation of polyethylene particles, is an important consideration when choosing a posterior cruciate retaining or a posterior cruciate sacrificing or substituting knee implant.
Patients must accept risk for polyethylene wear if they choose to participate in athletics after total knee arthroplasty. Patients who lead sedentary lives after knee replacement have very little risk of particulate-induced osteolysis, and patients who are very active have increased risk for having particulate-induced osteolysis develop. It is safe for orthopaedic surgeons to recommend low levels of activity after knee replacement. However, patients seek knee replacement to reduce their pain and increase their activity. Patients need to understand the risks associated with wear of the bearing surface. Patients should not be discouraged from participating in athletic activity. As a new millennium begins, new polyethylenes, ceramics, metals, and composite materials are being evaluated for improved wear characteristics at the bearing surface of knee replacements. The material effects of wear and the generation of particles may be the most important considerations of patients and orthopaedic surgeons when considering athletic activity after knee replacement.
Published Literature Regarding Total Knee Arthroplasty and Athletic Activity
Bradbury et al 3 evaluated participation in sports after total knee replacement in 160 patients who had 208 knee replacements. Seventy-nine patients participated in sports at least once a week before knee replacement surgery, and 51 patients participated in sports at least once a week after knee replacement surgery. Of the patients who played sports before knee replacement surgery, 65% played sports after surgery. Some patients (20%) returned to high-impact activity, such as tennis, whereas many patients (91%) returned to low-impact activities, such as bowling.
Mallon and Callaghan 14 surveyed 55 members of the Knee Society and active golfers with knee replacements to evaluate the performance of total knee arthroplasty in golfers. Of the Knee Society surgeons, 92% did not discourage their patients with knee replacements from playing golf, 96.4% stated that their patients who played golf did not have an increased rate of complications with their knee replacement, and 66% recommended the use of a golf cart to their patients who played golf after knee replacement. These authors 14 also surveyed 83 active amateur golfers with a unilateral primary total knee implant at a minimal followup of 3 years. These golfers played an average of 3.7 rounds of golf a week. After knee replacement surgery, these golfers noted their handicap rose an average of 4.6 strokes, and their drive length decreased an average of 12.2 yards. Of these golfers, 87% used a golf cart; 84% had no pain when playing golf, but they had a mild ache in the replaced knee after playing golf. More golfers with left knee replacement complained of pain associated with playing golf than did patients who underwent right knee replacement. Patients returned to playing golf an average of 18 weeks after total knee arthroplasty. Total knee arthroplasty survivorship and revision surgery were not evaluated in this study.
Twenty-eight surgeons at the Mayo Clinic (13 attending surgeons and 15 fellows and residents) completed a questionnaire regarding recommended or discouraged activities after knee replacement. 15 Responses from consultant surgeons, fellows, and residents did not differ significantly, except the responses for cross-country skiing. Recommended sports after total knee arthroplasty included sailing, swimming, scuba diving, cycling, golfing, and bowling. Athletic activities that were discouraged after knee replacement surgery included running, water skiing, football, basketball, hockey, handball, karate, soccer, and racketball. These authors concluded that participation in no-impact or low-impact sports was recommended after knee replacement surgery. These surgeons discouraged participation in high-impact athletic activity.
1999 Knee Society Survey
In preparing the current review article, 112 members of The Knee Society were surveyed regarding their recommendations for athletics and sports participation for patients who had knee replacements. Fifty-eight members of the Knee Society responded to the survey. Forty-two activities were presented to the surgeons, and they were asked to assign each activity to one of four categories: recommended or allowed, allowed with experience, no opinion, or not recommended. The 58 responses were analyzed with the Statistical Package for the Social Sciences (SPSS Inc, Chicago, IL) sample power module to determine a consensus recommendation. A power calculation for a one-sample proportion was performed, and a valid percentage of 73% was required to achieve significance.
According to the 58 surgeons, recommended activities after knee replacement surgery included low-impact aerobics, stationary bicycling, bowling, croquet, ballroom dancing, jazz dancing, square dancing, golf, horseshoe shooting, shuffleboard, swimming, and walking (Table 2). Road bicycling, canoeing, hiking, rowing, cross-country skiing, stationary skiing, speed walking, tennis, and weight machines were recommended if the patient previously participated in these activities (Table 3). In general, high-impact activities were not recommended. These activities included high-impact aerobics, baseball and/or softball, basketball, football, gymnastics, handball, hockey, jogging, lacrosse, racketball, squash, rock climbing, soccer, singles tennis, and volleyball (Table 4). No statistically significant conclusion could be made regarding fencing, roller blading or in line skating, downhill skiing, and weightlifting.
Authors’ Recommendations: Athletic Activity and Total Knee Arthroplasty
Patients with arthritic knees choose to have knee replacement to relieve pain, correct deformity, and improve function. The desire to improve function and continue participation in athletic activity is more important to patients now than it was 10 years ago. Patients should participate in whatever activities they wish after total knee arthroplasty. Physicians who perform reconstructive knee surgery should educate patients regarding risks associated with higher levels of activity, including the risk of trauma, implant loosening, and wear at the joint bearing surface.
Patients are strongly encouraged to avoid recreational and athletic activities until their quadriceps and hamstring muscles are rehabilitated sufficiently. Muscular rehabilitation is important for safety and protection of the joint. After muscle strength has recovered, the patient is permitted to make reasonable choices regarding athletic activity. In general, patients are encouraged to select low-impact activities.
Total knee arthroplasty can predictably relieve pain and improve function for a painful arthritic knee. Participation in athletics increases risk for bearing surface wear and loosening of implant fixation. In general, orthopaedic surgeons who offer patients joint replacement recommend or permit lowcontact, low-impact athletic activity. High-contact, high-impact athletic activity is discouraged for the patient who has undergone joint replacement. Athletic activity is important to many patients, and surgeons should educate patients regarding risks associated with athletic activity rather than discourage the activity. When patients with knee replacements choose to participate in athletic activity, they must understand the risks and benefits related to athletics and their total knee arthroplasty.
The authors thank members of the Knee Society who participated in a survey of their opinions and recommendations regarding athletic activity after total knee arthroplasty.
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William L. Healy, MD; and Richard S. Laskin, MD Guest Editors