Pre-operative exercise has been shown to improve total knee arthroplasty outcomes, but may not be feasible in patients with severe pain. Bracing and other offloading methods can help decrease that pain, potentially improving the effects of prehabilitation.
By John Kenney CO and Robert Hamblen MD, Lower Extremity Review October 2010
The American College of Rheumatology recommends that aerobic, range-of-motion and muscle-strengthening exercises, along with physical therapy and assistive devices for walking all be included in the management of osteoarthritis (OA) of the hip and knee. Because the number of people with OA is expected to increase dramatically over the next 10 years, and because most of these people will not require surgery, a pressing need is development of non-operative care that will relieve pain, improve function, and delay progression of the disease. But for those who do need surgery, recent studies are showing that pre-operative exercise programs help to prepare patients for surgery by strengthening the affected knee and improving functional ability.
These programs have been termed “prehabilitation”. The primary goal, based on the concept that a stronger, more functional knee before surgery will accelerate a person’s recovery after surgery, is to increase knee strength and functional ability while reducing pain. Programs can consist of a combination of exercises including walking, chair rises, and stair climbing and descending. Models have been developed that could improve outcomes after total knee arthroplasty (TKA), with one described in a previous issue of Lower Extremity Review. However, evidence of the benefits of prehabilitation is limited, but is still building. A PubMed search, for instance, on the term “prehabilitation” alone without date limits produced only 44 publications as of early October of this year.
One study found that improving knee strength, range-of-motion, and the ability to perform functional tasks, coupled with reducing overweight and obesity among patients, before TKA may contribute to higher function levels after TKA.
Yet another study found little evidence that pre-operative exercise improved functional ability after surgery. A third study recommends that future research should focus on improving strength, range of motion, and functional task performance prior to TKA to improve functional performance after TKA.
A 2009 review of literature from 1998 to 2008 found that only three studies met criteria of using pre-operative exercise as the only intervention studied. The author concluded that more research is needed and that only a “pragmatic” recommendation could be made for prehabilitation for total hip or knee arthroplasty.
A newly published case study report points to likely benefits that can be derived from such programs. Brown et al, reported in the August issue of Physiotherapy Theory and Practice that one 69-year-old female patient whose left TKA was preceded by a prehabilitation intervention had a 30% improvement in functional ability, compared to a previous right TKA preceded by usual care. Prompting the patient to go ahead with the surgeries were knee pain, joint stiffness, and decreased functional ability.
The prehabilitation program consisted of four weeks of exercises designed to improve performance on functional tests including a six-minute walk, sit-to-stand chair rises completed in 30 seconds, and the time to ascend, then descend two flights of 11 stairs each.
During prehabilitation, measurements were taken four weeks prior to TKA, again just prior to TKA, then one month and three months following TKA. Results show that she experienced more than a 50% gain in extension strength in both knees and a 34% (left) and 54% (right) gain in flexion strength just prior to the second surgery compared to four weeks prior to surgery. Following the second surgery, she maintained the strength in her right leg but not in the left. Although the patient experienced higher pain levels during prehabilitation, she returned to lower pain levels three months after the left TKA.
Jaggers et al, reported on a similar case study in a 2007 article in the Journal of Strength and Conditioning Research. That study compared the results of a 62-year-old woman who participated in a four-week prehabilitation program prior to a right TKA to those of a 57-year-old woman who underwent usual care prior to having a right TKA. The prehabilitation protocol emphasized resistance training, flexibility, and step training.
Functional testing evaluated distance covered in a six-minute walk, number of chair rises in 30 seconds, proprioception, and pain and function as measured using the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index. The prehabilitation patient experienced a 26% improvement in six-minute walk distance and a 1100% improvement in perceived pain 12 weeks after surgery compared with five weeks before surgery, while the usual care patient experienced a 2% decline in six-minute walk distance and a 350% improvement in perceived pain. The authors suggest that prehabilitation could reduce the length of hospital stay and the amount of rehabilitation after surgery, and it could help to reduce the cost of overall care for TKA patients.
Rooks et al, reported on a study involving 108 men and women scheduled for total hip arthroscopy (THA) or TKA in a 2006 article in Arthritis & Rheumatism. Patients were randomized to an intervention group that performed six weeks of exercise prior to surgery or to a control group that received education only. The patients in the prehabilitation group exercised three times a week for six weeks prior to surgery. The first three weeks of exercise consisted of repeating single-joint movements while standing chest-deep in a pool. The next three weeks focused on the total body and included cardiovascular, flexibility, and strength exercises.
Of the 49 patients who completed the study, 65% of the exercisers went directly home after inpatient surgery stays and 35% went into inpatient rehabilitation, compared with 44% of the control group going home after surgery and 56% going into inpatient rehabilitation. Also, 76% of the exercisers walked on the third day of inpatient care, compared to 61% of the control group. For hip and knee patients, the prehabilitation intervention reduced the odds of needing post-surgery inpatient rehabilitation by 73%.
However, the TKA patients in the prehabilitation group experienced a worsening of pain during the intervention prior to surgery. And the TKA exercisers did not improve in function levels as well as THA exercisers, although both groups increased their lower extremity muscle strength prior to surgery.
Topp et al, reported on a study to examine effects of prehabilitation on functional ability, knee pain, and quadriceps strength among TKA patients before and after surgery in a 2009 article in Physical Medicine & Rehabilitation. Of the 54 patients recruited for the study, 28 were randomized to a control group and 26 to a prehabilitation group.
The prehabilitation protocol included resistance training, flexibility, and step training three times a week for a minimum of four weeks. Prior to surgery, the prehabilitation group exhibited a significant improvement in sit-to-stand ability and a nonsignificant trend toward improvement in three other tasks, as well as a trend toward improved quadriceps strength.
The control group reported greater pain just before surgery, compared with baseline levels, while walking and doing sit-to-stand exercises, and showed a nonsignificant trend toward declining performance in functional tasks decreased knee strength prior to surgery. One month after surgery, the prehabilitation group maintained improvement in sit-to-stand and had no other changes.
The control group showed a decreased performance in walking and a decrease in quadriceps strength in the surgical knee compared with baseline. The authors suggest that these and other study findings support the efficacy of prehabilitation but also show a need for further research.
Limitations to these studies point to how to improve future research. The Brown study authors suggest that a more aggressive prehabilitation intervention that lasts more than four weeks, perhaps for six to 12 weeks, prior to TKA would produce more improvement in strength.
Authors of the Jaggers study recommend research be conducted on a much larger scale. Rooks et al, recommend focusing in more on TKA patients rather than multiple joint replacements and looking at the cost effectiveness of prehabilitation programs for TKA patients, as well as making future studies as convenient as possible for participants.
Authors of the Topp study suggest that the self-selected participants in their study may have had positive expectations that led them to clandestinely participate in other types of exercise or increase their physical activity before surgery. Also, the study did not track consumption of pain medication. Standardization of prehabilitation sessions prior to surgery would also be beneficial, Topp et al, concluded.
One limitation of prehabilitation interventions to date is that patients with osteoarthritis symptoms severe enough to necessitate surgery may also find that their pain impairs their ability to perform exercises, so that they may not realize the full potential benefit of a prehabilitation protocol. The fact that Brown and Rooks both reported that patients experienced increased pain during prehabilitation underscores this issue and raises the possibility that prehabilitation patients in both studies might have experienced even more positive outcomes if their pain during exercise could have been managed more effectively.
Bracing and prehabilitation
Knee braces that unload the affected compartment and improve underlying mal-alignment have the potential to address this problem. Research has shown that mal-alignment of the leg is the most influential factor in load distribution across the medial compartment of the knee.
Research suggests that so-called “unloader” braces, which typically employ a three-point bending mechanism, can decrease pain and increase function in patients with knee osteoarthritis, although the degree of efficacy observed varies between studies, and comparative studies of different types of braces are limited.
Pollo et al, tested 11 patients in 2002 and reported that during gait, bracing effectively reduced medial compartment load, reduced pain, and improved knee function in OA patients. Another study by Pollo and Jackson showed that bracing significantly increases function and reduces pain when used in managing OA. A 2006 analysis by Dennis et al, suggested that unloading knee braces vary in effective treatment for uni-compartmental knee OA.
Draganich et al, compared the use of self-adjustable custom braces with off-the-shelf models and concluded that, while patients with varus gonarthrosis can experience at least short-term benefit from any of the braces, the custom braces produced added benefit over and above off-the-shelf braces. Rannou et al, recommended in a 2010 paper that braces be included in treating knee OA, and that the various types be adapted to the symptomatic knee compartment, but also called for good clinical trials into the modalities.
The improvement in symptoms associated with OA bracing is thought to result from a valgus moment applied by the brace in patients with medial compartment OA, which counteracts the elevated external varus moment typically seen during gait in this patient population. Several studies have demonstrated that valgus OA bracing reduces knee adduction moment during walking by as much as 33% and during running by up to 11%, depending upon the valgus angulation of the device.
The typical unloader brace used in such studies features upper and lower thermoplastic cuffs and a diagonal strap that provides the third point in the leverage mechanism. However, a 2009 finite element analysis study suggests that a different type of brace design, featuring soft conforming materials and a pneumatic leverage system of air bladders, could potentially offset varus loading to an even greater extent.
Prehabilitation versus usual care before total knee arthroplasty: A case report comparing outcomes within the same individual, Brown K, Swank AM, Quesada PM, Nyland J, Malkani A, Topp R. Physiother Theory Pract. 2010 Aug;26(6):399-407. doi: 10.3109/09593980903334909.
The effect of bracing on varus gonarthrosis, Kirkley A, Webster-Bogaert S, Litchfield R, Amendola A, MacDonald S, McCalden R, Fowler P. J Bone Joint Surg Am. 1999 Apr;81(4):539-48.