Physical therapy post-TKA

my left knee back to front view after total knee replacement

I get to follow a patient with a TKA post-d/c (I like it when a SNF has an outpatient clinic!). In my previous clinicals I did not have a patient with a joint replacement, so I did a review on the APTA’s Hooked on Evidence and found an article that might help guide my decision-making:
Petterson SC, Mizner RL, Stevens JE, Raisis L, Bodenstab A, Newcomb W, Snyder-Mackler L. Improved function from progressive strengthening interventions after total knee arthroplasty: a randomized clinical trial with an imbedded prospective cohort. Arthritis & Rheum. 2009; 61:174-183.

Why the study matters: There is currently no evidence base for what rehab is best for post-TKA.  “In addition, a [NIH]-sponsored consuensus development conference on TKA concluded that ‘the use of rehabilitation services is one of the most understudied aspects of the perioperative managment of patients following [TKA]’ and ‘there is no evidence supporting the generalized use of any specific preoperative or postoperative rehabilitation interventions.'”

Hypotheses:  The authors thought that NMES and  progressive resistive exercise (PRE)  would give better results (strength, activation, and function) than PRE alone, measured at 3 and 12 months.  They also thought that patients in the combination group would have better ROM, better function by self-report, and less pain.  By using an imbedded cohort of “standard” treatment, they thought that PRE with or without NMES would give patients better results in strength, activation, and function but similar ROM, pain, and self-reported function than those who received standard care in the community.

Outcome measures: Primary: quad strength and activation testing by a burst superimposition technique, Timed Up and Go (TUG), Stair-Climbing test (SCT), and 6-Minute Walk Test (6MWT).  Secondary: self-assessment questionaires (SF-36, Knee Outcome Survey Actviites of Daily Living Scale (KOS ADLS – which includes a pain scale), and knee ROM.

Subjects/ patients: 50-85 y.o. scheduled to have a unilateral TKA by 3 orthopods.  Exclusion criteria were: uncontrolled HTN, DM, BMI >40, symptomatic OA of other knee (pain >4/10 VAS), other LE ortho problems impeding function, neuro impairment, residence >20 miles from clinic.  The TKA was a tricompartmental cemented TKA with medial parapatellar surgical approach.  Pts received inpatient rehab and home health PT before participating in the study.  For the imbedded prospective cohort, the authors recruited the pts of one surgeon who met the criteria but couldn’t participate in the trial but agreed to be tested 12 months after the surgery.

Intervention: starting 3-4 weeks after the surgery, pts were evaluated by 2 independent licensed PT’s, then enrolled in OP rehab at University of Delaware PT Clinic where they were randomly assigned into one of the groups – 100 into progressive volitional strength training (PRE), and 100 into the NMES/PRE group.  Both received PT 2-3x/wk for 6 weeks, at least 12 visits.  The PRE targeted the quad femoris, with weight based on the initial evaluation and continued assessments.  Exercises also addressed the hamstrings, gastroc/soleus, hip abductors, and hip flexors. Exercises were in 2 sets of 10, then progressed to 3×10 with increased in weight to maintain 10 RM level.  NMES involved 10 elicited contractions of the quad femoris with the knee at 60 degrees and the person in an electromechanical dynomomter (the authors were very specific as to the size of electrodes and the settings of NMES) with the goal of 30% force output of the person’s daily maximal volitional isometric contraction force.  Followup assessments were completed 3 and 12 months post-TKA by investigators who were blinded as to the patient’s group in the study, and consisted of active knee ROM, TUG, SCT, 6MWT, and quad strength and activation.

Results: no significant difference between the PRE and PRE/NMES groups on any of the outcome measures at 3 and 12 months, with both improving on all measures both times (except SF-36 only at 3mo).  Comparing it to the “standard of care in the community” group (who had more PT sessions than the RCT participants), they noted that the intervention group had more strength, more NMVIC, better functional performance (TUG, SCT, 6MWT) at 12 months but no significant difference on the secondary outcome measures.

What I would like to know more about: the KOS ADLS (reliability/validity, what do the numbers mean and what is a clinically significant improvement?); the PRE program (what percentage of 10RM did they regularly lift?  How often was it assessed?  How did they choose the weight for the other muscle groups?); further comparison of the imbedded group vs the RCT group (what else might account for the difference – PT approach?  Adherence to HEP?  And the range for the imbedded group PT visits was 0-46 – wouldn’t it have been better to compare those with at least 12 visits to the RCT group?  And did any in the RCT group continue with PT past the 6 week timepoint?).

How this will affect my clinical practice:  I will use PRE for most of my TKA patients (with careful planning for those with osteoporosis), but I’m not sure that NMES is worth the setup time, discomfort, etc (and I don’t have an electromechanical dynomometer).  I’ve chosen outcome measures including the ones they used in this study, with additional balance/gait measures as necessary.

Picture credit: my left knee back to front view after total knee replacement, originally uploaded by dharmabox

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