1. a randomized controlled trial
Feasibility, safety, and effects of early high-intensity strength exercises following total knee replacement:
a randomized controlled trial
Marivo Simone1, PTs; Vercelli Stefano2, PhD PT; Sartorio Francesco2, MSc PT;
Morra Valentina3 PTs, Piano Leonardo4 OMPT
1Student at School of Physiotherapy - University of Eastern Piedmont, Novara, Italy.
2Laboratory of Ergonomics and Musculoskeletal Disorders Assessment, Istituti Clinici Scientifici Maugeri SpA SB - IRCCS, Veruno (NO), Italy.
3Student at School of Physiotherapy, University of Eastern Piedmont, Fossano (CN), Italy 4Unit of Rehabilitation and Functional Recovery, Casa di Cura La Residenza, Rodello (CN), Italy
Background and Objective
The full recovery of strength and function after total knee arthroplasty (TKA) is uncommon,1,2 and patients are frequently exposed to future disability. Despite these known impairments and activity limitations, there is a lack of established standards for prescribing exercise paradigms.3 However, there is preliminary evidence that early, progressive high-intensity rehabilitation can lead to better outcomes.4
Aim of this study was to analyze the safety and effects of a three-weeks, high-load (HI) strength training compared to controls who underwent a low-intensity (LI) rehabilitation program.
Material and Methods
A total of 39 inpatients with primary unilateral TKA were recruited in two rehabilitation institutes, and randomized to the HI (N=18) or LI (N=21) group. A sample size of 18 subject per group was needed. Both groups received a comprehensive low-intensity treatment aimed to improve strength, ROM, gait, and function. In addition, the HI group included two high-intensity strength exercises (leg extension and squat) three times a week.5
Patients were assessed by means of maximal quadriceps strength in open and closed kinetic chain. The two groups were compared by a two-ways ANOVA. Any complaint (increase of pain/swelling or decreased of walking endurance/knee ROM) was also recorded. Safety was assessed with the percentage of dropout, defined as the ratio between the number of patients who withdrew from treatment and the number of patient enrolled in the same group.
Figure 1. Comparison of strength tests between groups over time (Tukey box plots). On the left is shown the maximal strength in the leg extension test, expressed in kilograms; on the right, the maximum number of repetitions executed in the squat test (the minimum height recorded for each patient during the squat test at admission was maintained at discharge). Abbreviations: HI, high-intensity group; LI, low-intensity group; LE_t0, Leg Extension at admission; LE_t1, Leg Extension at discharge; Squat_t0, Squat test at admission; Squat_t1, Squat test at discharge; *, statistical significance at p<0.05; **, statistical significance at p<0.01. Boxes are the first and third quartiles, the band inside the box is the mean, the whiskers represent the lowest value still within 1.5 IQR of the lower quartile, and the highest value still within 1.5 IQR of the upper quartile.
Results
At discharge, the HI group had greater maximal quadriceps strength (Table 1) in both the leg extension (p<0.05) and squat (p<0.01) compared to the control group (Figure 1). The high-intensity exercises were well tolerated, and no subject withdrew from treatment.
Discussion
Results indicate that the addition of high-intensity exercises initiated early in the course of recovery after TKA led to superior strength outcomes, without leading to increase of pain, swelling or decrease of knee performances in this group of patients.
The key difference between the 2 programs was the level of intensity chosen for resistive strength training, and it is likely that treatment intensity was the primary driver of the differences in outcomes between groups. Safety of HI exercises was demonstrated by the absence of difference in dropout ratio or symptoms’ intensity between groups.
Leg extension T0 T1
Group
Mean (SD)
p25
p75 HI
5,1 (3,25)
2,3
6,3
11,6 (4,3)
8,2
14,3 LI
3,27 (3,26)
1,3
4,6
7,02 (4,89)
3,5 9
Squat
11,25 (3,71)
8,5 13
30 (10,68) 21 40
11,52 (6,87) 6 14
22,38 (10,85) 12 30
Conclusions
Introducing progressive submaximal exercise after TKA leads to increased muscular strength with no impairments that may slow down the recovery process or lengthen the time of hospitalization. The implementation of more intense interventions should be considered.
Table 1. Abbreviations: HI, high-intensity rehabilitation group; LI, low-intensity rehabilitation group; SD, standard deviation; T0, first day assessment; T1, last day assessment, Leg extension, maximal strength in open kinetics chain on leg extension machine expressed in KG; Squat, maximal strength in closed kinetic chain expressed in lower height maximum repetition in squat exercise.
References
1-Noble PC, Gordon MJ, Weiss JM, Reddix RN, Conditt MA, Mathis KB. Does total knee replacement restore normal knee function? Clin Orthop Relat Res. 2005;
2-Silva M, Shepherd EF, Jackson WO, Pratt JA, McClung CD, Schmalzried TP. Knee strength after total knee arthroplasty. J Arthroplasty. 2003;18:
3-Pozzi F, Snyder-Mackler L, Zeni J. Physical exercise after knee arthroplasty: a systematic review of controlled trials. Eur J Phys Rehabil Med. 2013;49(6):
4-Bade MJ, Stevens-Lapsley JE. Early high-intensity rehabilitation following total knee arthroplasty improves outcomes. J Orthop Sports Phys Ther 2011;41:
5-American College of Sports Medicine. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Med Sci Sports
Exerc. 2009;41(3): doi: /MSS.0b013e