Study design
The study is a multi-center randomized controlled trial comparing the effect of intensive early postoperative physiotherapy with the current standard of physiotherapy for patients undergoing elective THA for unilateral OA. General Hospital Novo mesto and Valdoltra Orthopedic Hospital are involved in the project, and the standard physiotherapy program for patients after THA is similar in both hospitals. All patients who will receive an anesthesiologist’s approval and will already be scheduled for surgery will be assessed for eligibility. They will be invited to participate, will receive oral and written explanations about the trial and will be included in the study after signing a written informed consent form. After admission to the hospital, they will complete the routine preoperative outcome assessment questionnaires (Harris Hip Score (HHS) and 36-Item Short Form Health Survey (SF-36)) and have standard preoperative AP X-rays of both hips taken. Physiotherapists will perform the assessments: physical tests and an isometric muscle strength assessment. In both hospitals, the included patients will be randomized to either the intervention group (IG) or the control group (CG), and the surgeons and patients will be blinded to the randomization process. The procedure will be performed with the direct anterior approach only in the General Hospital Novo mesto by 1 surgeon and in the Valdoltra Orthopedic Hospital by 4 surgeons. Patients will be mobilized on the day of surgery. During the expected LOS of 2–5 days, all patients will receive current standard physiotherapy, oral analgesics and cryotherapy. Patients in the IG will receive extra one-on-one training to learn strength and sensory-motor exercises. If the surgeon applies any limitations for a patient regarding rehabilitation after surgery, the patient will be excluded from the study. At discharge, patients in both groups will receive USB drives with exercise videos, written exercise instructions and a training diary. Patients in the IG will also receive exercise aids for the strength and sensory-motor training. All patients will be followed up with regular phone calls concerning possible complications, completion of the training diary, and the clarity of the exercises. The patients will visit the hospital as usual after 1, 3 and 12 months following surgery. At each follow-up, the physiotherapists will perform assessments, and patients will fill out questionnaires. The patients will have a standard postoperative X-ray of the operated hip immediately after the surgery and AP X-rays of both hips after 1 year, so we will be able to compare measurements of the hip offsets of the operated and healthy hips and observe any changes regarding component position or osteolysis. At every follow-up, the surgeon and physiotherapist will ask the patient about any adverse effects or reasons for training cessation. The trial flowchart is displayed in Fig. 1.
Study intervention
Standard rehabilitation
All patients will receive standard of care physiotherapy during hospitalization. Physiotherapy will commence on the day of surgery with mobilization using a walking aid (usually two crutches, rarely a walker), deep vein thrombosis prevention exercises, lower limb range of motion exercises and an isometric strengthening program. Patients will be encouraged to perform exercises twice daily, with approximately 10 repetitions of every exercise, and walk as much as possible. Exercises will be performed in a supine position, on the healthy side, on the abdomen, sitting and standing (e.g., buttock squeezes, leg sliding motions, straight leg raises, bridges, postural exercises). Patients will be discharged based on a combination of compliance with the exercises, stability with a walking aid, independence with activities of daily living and dry wounds. Patients in the CG will receive written instructions, a USB drive with videos of standard exercises and a training dairy at discharge.
Prescribed home-based strength and sensory-motor training
Before the patients are discharged, physiotherapists will teach patients in the IG special strength and sensory-motor exercises with exercise aids. The patients will also receive USB drives with special exercise videos, written exercise instructions and a training diary to check performed exercises. The new training protocol includes exercises for improving hip stability and reducing local stresses on the hip prosthesis. In the training, we considered safety regarding hip and lumbar spine load, falls and prosthesis luxation. Training will consist of: hip muscle strengthening exercises (focusing on the abductors); hip and pelvic stabilization exercises; ankle and knee muscle strengthening exercises (for improved dissipation of impact forces and femoral inner rotation control); and trunk muscle strengthening exercises (for stabilization of the pelvis and lumbar spine and a reduction in local loads). We ensured the exercises are simple and easy to understand, the videos that are to be watched at home are easy to follow, and the training program does not require expensive equipment. In the first two postoperative weeks, the focus is on learning the proper exercise technique and developing a sense of loading. Patients will watch special instructional short videos with exercise descriptions. Each exercise will be demonstrated with easy and challenging options as well as oral and written instructions. We will use a revised Borg category-ratio scale (0 to 10 scale) for perceived exertion to monitor and guide exercise intensity 31. In sets of fluent concentric repetitions of movements (10–12 repetitions per set), the rating of perceived exertion will be recorded for the last repetition. When holding an isometric position, the rating will be recorded for the end of interval (with a lengthening of the interval to 30 seconds, until we can achieve desired perceived exertion at the end of the interval). In sets of isometric contractions, every repetition will be made with maximal voluntary effort exerted for 6 seconds (2 seconds for force increments and 4 seconds for maintenance). The implementation of fluent concentric movements is intended to increase muscle mass and improve physical endurance, while maximal isometric contractions are used for improving the level of muscular activation 32. Exercises with isometric trunk positions will be prepared with recommendations for isometric trunk stabilization training 33. These concepts collectively allow for individual load adaption for every exercise regarding individual patient abilities and load progression in accordance with his or her progress in muscle strengthening training 32. Each session consists of a warm-up with 2 options (5–7 minutes of toe walking on the same spot or step-ups on a 10 cm tall step), strength training for both legs (30–40 minutes; 11 exercises; 1–4 fluent concentric repetitions of the single-leg squat and lying side hip raise; 5–8 maximal isometric contractions of the sitting ball squeeze, seated elastic band hip abduction, and diagonal ball push into the opposite thigh; 9–11 holds in the isometric positions, side plank and bridge) and stretching (standing hip flexor stretch, sitting forward bend stretch, standing lateral trunk stretch). Strength training will be performed twice weekly, with a minimum of 2 days of rest. Until the 5th postoperative week, perceived exertion will be increased on the Borg scale from 5 to 8, and then it will be increased to 9 until the assessment at 3 months. In the first 5 postoperative weeks, 2 sets of each exercise will be recommended, and after these 5 weeks, 3 sets will be recommended. Sensory-motor training will be added to strength training to increase muscular activation and rate of force development and will be practiced on the days without strength training 34. Exercise for ankle stability will be performed with a one-dimensional wooden balance board in the frontal and sagittal plane 35. At the beginning, patients will perform 6 sets for each leg and 12 sets after the 7th postoperative week. The intensity of the exercise will be increased according to patient abilities with changes in the stability of the balance board. For every exercise, severe pain will be a reason for training cessation and contact with the physiotherapist.
Outcome measures
This paper is written according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) 2013 Statement for the reporting of clinical trial protocols (Table 1, Additional file 1) 36, 37. The primary outcomes are those of the physical tests, which comprise isometric muscle strength, the 10MW test and the 8-foot Up and Go (8UG) test. Secondary outcomes are the patient reported outcome measures: HHS and SF-36.
Table 1
SPIRIT-Figure 36, 37: Schedule and outcome measurements preoperatively and at 1, 3 and 12 months postoperatively
Timepoint | Preop | Discharge | 1 month | 3 months | 1 year |
ENROLLMENT: | | | | | |
Eligibility screen | X | | | | |
Informed consent | X | | | | |
Group allocation | X | | | | |
INTERVENTIONS: | | | | | |
Intervention group (IG) | | x---------------------------------------x | |
Control group (CG) | | x---------------------------------------x | |
ASSESSMENTS: | | | |
Patient demographics | X | | | | |
Isometric muscle strength | X | | X | X | X |
8UG | X | | X | X | X |
10MW | X | | X | X | X |
HHS | X | | X | X | X |
SF-36 | X | | | X | X |
X rays | X | X | | | X |
Complications | | | X | X | X |
Trial baseline is on the day of hospital admission, one day before surgery. Assessment timeframes are calculated from the date of surgery.
Maximal voluntary isometric contractions
We use a specially prepared measuring device with a dynamometer attached to stiff band metal chains, prepared similarly to those in Roussel et al and Essendrop et al 38, 39. The ICC for a similar device, used by one of the senior authors for lumbar muscle strength assessment, is > 0.94. For the assessment of maximal isometric strength, a maximal voluntary isometric contraction for 6 seconds is used. The same procedure of obtaining a maximal voluntary contraction is used for every strength measure. Movement is assessed in 3 planes for the trunk (extension, left and right abduction) and operated hip (flexion, extension and abduction), and movement is assessed in 2 planes for the contralateral hip (extension, abduction). All strength tests are performed in a neutral standing position, and the patient rotates on the measuring device so that the exerted force is always in the direction opposite of the dynamometer. Before the measurements, the height of pelvic support is set to the reference point of the iliac crest of each patient. Patients are verbally encouraged to generate maximal effort. The mean duration of the complete test is 20 minutes. We wrap the band around the trunk under the armpits for trunk tests and around the ankle for leg tests. We measure the height of pelvic support, maximal contraction force and distance between the upper border of the support board and the middle point of the stiff band. All measurements are taken twice.
Physical performance tests
We will make videos of patients performing both physical tests, and later, one independent researcher will review them. All tests will be performed twice. If possible, the patient will walk without walking aids; if a patient is unable to perform a test without help, this instance will be allowed and noted.
8-FOOT UP AND GO TEST
For the Timed Up and Go (TUG) test, the time that a person takes to rise from a chair, walk 3 meters, turn around, walk back to the chair, and sit down is measured 40. This test is used to assess mobility, balance, walking ability and fall risk in elderly populations. The original version of the TUG test has been critiqued because of the potential for confusion with its instructions and the line on the floor. To address this limitation, Rikli and Jones modified the TUG test to create the 8UG test by reducing the distance to 8 feet and replacing the line on the floor with a cone to signal the turn-around point 41, 42 43. The 8UG test has better sensitivity than the TUG test when traditional cut-off times are applied. The 8UG test with a cut off time of 8.5 seconds should be used as a threshold for identifying persons with an increased risk of falling 42, 43. The 8UG test is a timed test that requires one to stand up from a chair with armrests, walk to a cone 8 feet away, turn around, return to the chair and sit down 42.
TIMED 10-METER WALK TEST
The speed at which individuals walk is relevant to their functional abilities in the community 30,44. Gait speed is also an important predictor of outcomes, such as hospital LOS and discharge disposition of patients admitted for acute rehabilitation after a stroke, mortality of older adults, incident ischemic stroke among postmenopausal women and incident dementia among older adults 44. For this test, the individual walks 10 meters without assistance, and the time the individual takes to walk the intermediate 6 meters is measured to allow for acceleration and deceleration periods 45. We measure and mark a 10-meter walkaway and add a mark at 2 and 8 meters. The test is first performed at preferred walking speed and performed a second time at the fastest speed possible 45.
Questionnaires
HARRIS HIP SCORE
The HHS is a widely used disease-specific measure of hip disabilities after THA. The physiotherapist administers the test in the form of a structured interview with the patients. The domains include pain, functions of daily living and gait. The rating scale is from 0 (worse) to 100 points (best) 46. The HHS is considered to have good validity and reliability 47.
36-ITEM SHORT FORM HEALTH SURVEY
The SF-36 Health Survey was first made available in standard form in 1990. The eight health domains represented in the profile were selected from the 40 domains that were included in the Medical Outcome Study (MOS) by Stewart and Ware 48. The RAND 36-Item Health Survey (Version 1.0) is a set of generic, coherent, and easily administered quality-of-life measures. It taps eight health concepts: physical functioning, bodily pain, role limitations due to physical health problems, role limitations due to personal or emotional problems, emotional well-being, social functioning, energy/fatigue, and general health perceptions. It also includes a single item that provides an indication of perceived change in health 49. These 36 items, presented in RAND 36-Item Health Survey 1.0, are identical to the MOS SF-36 described in Ware and Sherbourne 50. Scoring of the RAND 36-Item Health Survey 1.0 is clearly described in scoring instructions 49. The survey is a practical, reliable and valid measure of physical and mental health. In our study, we will use the Slovenian translated and validated version by Marn-Vukadinović et al 51.
Training compliance
All participants in both groups will keep a training dairy concerning all training activities; they will make marks by every exercise they perform on each day, write notes if they will perform any other sport activities (walking, stationary bicycling and others), note any adverse effects, and note reasons for skipped training exercises if applicable. They will also record their pain level by using the Visual Analog Scale (VAS) 52 during the day, before and after training, and during the night.