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Patients Undergoing Total Knee Arthroplasty: Maximizing Postoperative Outcomes Through Prehabilitation

 

Learning Objectives:

  • To educate health and fitness professionals about the benefits of prehabilitation for patients undergoing a Total Knee Arthroplasty (TKA).

  • To provide health and fitness professionals with an overview of the peer-reviewed literature for the efficacy of prehabilitation resistance training as a treatment for Total Knee Arthroplasty.

  • To provide health and fitness professionals with the guidelines for an effective and safe prehabilitation resistance training program for patients undergoing a Total Knee Arthroplasty.

One of the most common chronic health problems affecting more than 7 million Americans is Osteoarthritis (OA) (24). In the United States there are more than 381,000 TKAs performed annually and by the year 2030 the number of TKAs performed annually is predicted to increase by more than 600% (24).


OA leads to the need for TKA in order to alleviate pain and increase physical function (24). However, following a TKA, full recovery of strength and physical function is rare (18).


Low quadriceps muscle strength has been associated with patients

who have OA and it has been shown to be a direct predictor of functional ability. Because of this direct relationship, prehabilitation resistance training is often recommended (24) with the hope of improving post-operative outcomes for the patient.


Therefore, this article will review the peer-reviewed literature in respect to the effects of prehabilitation resistance training on patients undergoing total knee arthroplasty and its efficacy on their postoperative strength, pain, and functional ability.


Why Osteoarthritis Leads to Total Knee Arthroplasty

Patients suffering from OA report symptoms of achy, burning, or sharp pain in the knee. These symptoms can prevent patients from completing day to day tasks. As a result, the patient’s quadriceps muscle strength continues to decrease due to inactivity, failure of voluntary muscle activation, and muscle atrophy (10, 16). It is typical to see abnormal gait patterns in patients suffering from OA in order to compensate for their symptoms and loss of quadriceps strength (14).

 
Postoperative Problems Following TKA
TKA is performed in order to reduce pain and improve knee function (18). However, it is not that simple; there are still biomechanical, strength, and functional ability issues following the surgery.


Biomechanical compensation caused by knee pain leads to altered joint loading and compensation in the trunk and opposite leg along with decreased hip and knee flexion, resulting in reduced strength in the operated leg known as “quadriceps avoidance” (15, 27). Gait asymmetry occurs for 3 months following TKA and improves gradually up to 12 months postoperative (26).

 

Following a TKA patients exhibit a significant decrease in the contribution of the quadriceps muscles (vastus medialis, vastus intermedius, vastus lateralis, and rectus femoris) (15). This greatly affects the patients posture through the activation of trunk muscles during gait when walking as a compensatory response to aid momentum during propulsion; particularly in the erector spinae and the internal and external oblique muscles when compensating for “quadriceps avoidance” (14, 15).


Gait adaptive functional habits are seen pre- and post-operatively in TKA patients, such as increased dorsiflexion of the ankle during gait to compensate for impaired knee function (14). The increase in dorsiflexion of the ankle allows for a greater power output during propulsion, resulting in increased momentum during gait (14).

 In recovery, quadriceps dysfunction is often acknowledged and targeted during therapy. However, patients who undergo TKA show high levels of co-activation between the quadriceps and hamstrings (18). This excessive co-activation may result in impaired movement and overuse caused by muscle weakness in the operated knee potentially causing extra wear and tear on the knee prosthesis through increased compressive forces and joint loading (18), and chronic tendinopathy in the postoperative knee and leg; resulting in increased pain (18). Some patients have prolonged strength deficits in the operated leg. This is caused by adaptive functional habits such as co-activation and knee joint loading patterns that were learned prior to surgery to compensate for knee pain and decreased functional ability (10, 14).


Society is continually improving technology and this can result in patients expecting greater postoperative performance and this expectation continues to rise as the arthroplasty population becomes younger (10). However, quadriceps muscle function and strength are direct determinants of this outcome (10).


Role of Strength in Recovery
Resistance Training (RT) at 50%, 60%, 70% and 80% of 1 Rep Max increases muscle strength and power in men and women when performed 2-3 times per week over 4-6 weeks (9). These initial gains in strength are attributed to neural adaptations followed by gains in muscle hypertrophy after 6 weeks of RT (6, 13).

 Patient’s quadriceps strength does not return to preoperative values until 6 months following the TKA (27). If patients are participating in pre- and post- physical therapy and performing their prescribed exercises, why does it take so 6 months or more to recover preoperative strength, if they fully recover it at all? This leads to the following questions: is prehabilitation effective, should TKA patients be prescribed prehabilitation to improve postoperative outcomes, and what can we do differently to achieve these outcomes?


Why Prehabilitation Might be Effective
Patients suffering from OA and who participate in prehabilitation see a significant increase in quadriceps strength and reduced pain prior to surgery (23). Research has shown that lower quadriceps muscle strength prior to TKA is correlated with lower functional endpoints following TKA. Therefore, strengthening of the quadriceps through prehabilitation should theoretically improve functional ability and strength of the patient post-surgery (28) as well as improve gait during walking (15). It is known that hamstring dysfunction and co-activation is present following TKA, therefore in addition to quadriceps strengthening it could be suggested in theory that strengthening the hamstrings during prehabilitation would reduce postoperative co-activation and its side effects.

 
Adaptive functional habits are known to transfer from pre- to post- operative performance in patients, therefore it could be suggested that optimizing gait performance prior to surgery could theoretically improve gait and functional ability following TKA (14, 15).