Descriptive Study of Knee Joint Pain During Strength Training After Total Knee Arthroplasty
Condition: Knee Osteoarthritis
MeSH terms: Arthralgia
Study type: Interventional

Summary: 
      Background:

      In the early phase after a total knee arthroplasty (TKA), patients experience multi-level
      weakness in the operated leg, which is caused primarily by reduced central nervous system
      (CNS) activation failure of the muscles - especially the knee extensors. This considerable
      loss of muscle strength relates to reduced functional performance. Early-commenced,
      progressive strength training of the knee extensors of the operated leg therefore seems
      rational. However, the concern is that this type of early-commenced, intense physical
      rehabilitation exacerbates post-operative symptoms, such as knee joint pain.

      The investigators have recently reported that early-commenced physical rehabilitation,
      including progressive strength training of the knee extensors of the operated leg seems
      feasible after TKA. The classic exercise-physiology literature emphasizes loading and
      repetitions performed to contraction failure - among others - as important variables for
      muscle hypertrophy and strength gains. It is currently not known how loading and repetitions
      performed to contraction failure during knee extensions with the operated leg, influences
      post-operative knee joint pain in patients with TKA.

      Purpose and hypothesis:

      The purpose of this study is to investigate how loading and repetitions to contraction
      failure influence knee joint pain during knee extensions with the operated leg early after
      TKA.

      The hypothesis is that knee pain increases with increasing loading and fatigue.

      Methods:

      Fifteen patients with a unilateral TKA, operated between 1 to 2 weeks prior to the first
      investigation, will be included. The participants are investigated twice. During the first
      investigation, the absolute load (kilograms) corresponding to 10 Repetition Maximum (RM) (a
      load that can be lifted exactly 10 times) will be determined for unilateral (operated leg)
      knee extension. At the second investigation, at least 72 hours later, the patients will
      perform 1 set of 4 repetitions with a relative loading of 8, 14, and 20 RM each, in a
      randomized order, estimated from their 10 RM test at the first investigation. Time under
      tension (contraction velocity) and range of knee joint motion for each repetition will be
      controlled for. During the concentric phase of each repetition, the patients rate their knee
      joint pain verbally, using a numerical rating scale placed 1 meter in front of them. After a
      short break, the patients perform 1 set of knee extension with a relative loading of 10 RM
      until of contraction failure. As for the loading effect described above, they rate their knee
      joint pain during the concentric phase of each repetition.
    


Intervention name(s): Knee extension strength training
Intervention type(s): Other
Intervention description(s): Load experiment: Four knee extensions will be performed with the operated leg at 20, 14, and 8 RM loadings each, in a randomized order. Range of knee joint motion and time under tension for each repetition will be controlled for
Failure experiment: One strength training set of knee extensions will be performed with the operated leg at 10 RM loading until contraction failure. Range of knee joint motion and time under tension for each repetition will be controlled for
Intervention model: Single Group Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Total knee arthroplasty; Total knee replacement; Strength training; Resistance training; Physical therapy modalities; Fatigue