Paraspinal NMES and Spinopelvic Alignment After Knee Arthroplasty

Condition(s) studied

Investigational drug(s) / intervention(s)

Standard Postoperative Rehabilitation Program: A structured rehabilitation program including early postoperative mobilization (days 1-3: standing, short-distance ambulation, quadriceps isometric exercises, ankle pumping, breathing exercises, cold application), pre-rehabilitation phase (days 4-15: assisted ambulation, straight leg raise, passive range-of-motion exercises), and active rehabilitation phase (weeks 2-3: active-assisted knee ROM exercises, closed kinetic chain exercises, balance training, stair and gait training), along with pain and edema control throughout.

Quadriceps Neuromuscular Electrical Stimulation: Surface NMES applied bilaterally over the vastus medialis obliquus and rectus femoris muscles (long-sitting position, knee at 30° flexion). Parameters: 50 Hz frequency, 300-400 µs pulse width, duty cycle 1:3 (10 sec on-30 sec off), intensity titrated to patient tolerance to produce visible muscle contraction, 20 minutes/session, once daily, 5 days/week, for 4 weeks.

Paraspinal Neuromuscular Electrical Stimulation: Surface NMES applied bilaterally to the lumbar paraspinal muscles (erector spinae and multifidus) via 4 hydrogel electrodes placed bilaterally around the L4-L5 spinous processes, in prone position. Parameters: 50 Hz frequency, 250-350 µs pulse width, duty cycle 1:3 (10 sec on-30 sec off), intensity titrated to patient tolerance to produce visible muscle contraction, 20 minutes/session, once daily, 5 days/week, for 4 weeks.

Study summary

Total knee arthroplasty (TKA) is a widely performed surgical procedure for patients with severe knee osteoarthritis. Following TKA, changes in lower extremity alignment and gait mechanics may influence the spinopelvic sagittal alignment, and postoperative rehabilitation programs traditionally focus on the knee joint without addressing the lumbopelvic chain.

This study aims to investigate whether adding paraspinal neuromuscular electrical stimulation (NMES) to a standard postoperative rehabilitation program (which includes quadriceps NMES) affects spinopelvic sagittal alignment parameters in patients undergoing TKA for primary knee osteoarthritis, compared with standard rehabilitation and quadriceps NMES alone.

In this single-center, prospective, randomized, single-blind (outcome assessor-blinded) controlled trial, eligible participants aged 40-80 years with primary knee osteoarthritis scheduled for TKA and with measurable spinopelvic malalignment will be randomly assigned in a 1:1 ratio to receive either standard rehabilitation with quadriceps NMES plus paraspinal NMES (intervention group) or standard rehabilitation with quadriceps NMES alone (control group) for 4 weeks (20 sessions).

The primary outcome is the change in radiographic spinopelvic parameters - including pelvic tilt, sacral slope, pelvic incidence, lumbar lordosis, sagittal vertical axis, and spinosacral angle - measured on standing lateral whole-spine radiographs at baseline (preoperative), before rehabilitation, after the 4-week intervention, and at 6-month follow-up. Secondary outcomes include knee and back pain (VAS), functional and quality-of-life measures (WOMAC, Knee Society Score, Forgotten Joint Score, Oswestry Disability Index, Nottingham Health Profile), performance-based tests (Timed Up and Go, 6-Minute Walk Test), and knee range of motion.

The investigators hypothesize that adding paraspinal NMES to standard rehabilitation will result in greater improvement in spinopelvic alignment parameters, and potentially in clinical/functional outcomes, compared with standard rehabilitation alone.

Eligibility

Primary outcome measure(s)

• Change from Baseline in Pelvic Tilt (PT) — Baseline (preoperative, T0), before rehabilitation (postoperative, T1), end of 4-week intervention (postoperative week 6, T2), and 6-month follow-up (T4)
  Pelvic tilt will be measured as the angle between the line connecting the midpoint of the sacral plate to the center of the femoral head axis and the vertical line, assessed on standing lateral whole-spine radiographs (36-inch cassette) by two independent physicians blinded to group allocation. Measurements will be performed using PACS-integrated measurement software. Interobserver reliability (ICC ≥ 0.85) and intraobserver reliability (repeat measurement at 2-week interval) will be assessed. Unit of Measure: degrees
• Change from Baseline in Sagittal Vertical Axis (SVA) — Baseline (T0), before rehabilitation (T1), end of 4-week intervention (T2), and 6-month follow-up (T4)
  The horizontal distance between the C7 plumb line and the posterosuperior corner of S1 will be measured on standing lateral whole-spine radiographs. Unit of Measure: millimeters
• Change from Baseline in Radiographic Spinopelvic Angular Parameters (Sacral Slope, Lumbar Lordosis, Spinosacral Angle) — Baseline (T0), before rehabilitation (T1), end of 4-week intervention (T2), and 6-month follow-up (T4)
  Sacral slope (angle between the S1 superior endplate and horizontal), lumbar lordosis (Cobb angle between L1 and S1), and spinosacral angle (angle between the line connecting the C7 center to the sacral plate midpoint and the sacral plate) will be measured on the same standing lateral whole-spine radiographs described above. Unit of Measure: degrees

Trial sites (1)

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