title: Comparison of two stretching methods and optimization of stretching protocol for the piriformis muscle.
abstract: Piriformis syndrome is an uncommon diagnosis for a non-discogenic form of sciatica whose treatment has traditionally focused on stretching the piriformis muscle (PiM). Conventional stretches include hip flexion, adduction, and external rotation. Using three-dimensional modeling, we quantified the amount of (PiM) elongation resulting from two conventional stretches and we investigated by use of a computational model alternate stretching protocols that would optimize PiM stretching. Seven subjects underwent three CT scans: one supine, one with hip flexion, adduction, then external rotation (ADD stretch), and one with hip flexion, external rotation, then adduction (ExR stretch). Three-dimensional bone models were constructed from the CT scans. PiM elongation during these stretches, femoral neck inclination, femoral head anteversion, and trochanteric anteversion were measured. A computer program was developed to map PiM length over a range of hip joint positions and was validated against the measured scans. ExR and ADD stretches elongated the PiM similarly by approximately 12%. Femoral head and greater trochanter anteversion influenced PiM elongation. Placing the hip joints in 115° of hip flexion, 40° of external rotation and 25° of adduction or 120° of hip flexion, 50° of external rotation and 30° of adduction increased PiM elongation by 30-40% compared to conventional stretches (15.1 and 15.3% increases in PiM muscle length, respectively). ExR and ADD stretches elongate the PiM similarly and therefore may have similar clinical effectiveness. The optimized stretches led to larger increases in PiM length and may be more easily performed by some patients due to increased hip flexion.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA.
authors.forename: Brett M
authors.initials: BM
authors.lastname: Gulledge
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA; Department of Physical Therapy, College of Health, Education, and Professional Studies, University of Tennessee, Chattanooga, TN 37403, USA; Edward P. Fitts Department of Industrial and Systems Engineering, College of Engineering, North Carolina State University, Raleigh, NC 27695, USA. Electronic address: denis_marcellin@ncsu.edu.
authors.forename: Denis J
authors.initials: DJ
authors.lastname: Marcellin-Little
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA; Department of Physical Therapy, College of Health, Education, and Professional Studies, University of Tennessee, Chattanooga, TN 37403, USA.
authors.forename: David
authors.initials: D
authors.lastname: Levine
authors.affiliation: Department of Physical Therapy, College of Health, Education, and Professional Studies, University of Tennessee, Chattanooga, TN 37403, USA.
authors.forename: Larry
authors.initials: L
authors.lastname: Tillman
authors.affiliation: Edward P. Fitts Department of Industrial and Systems Engineering, College of Engineering, North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Ola L A
authors.initials: OL
authors.lastname: Harrysson
authors.affiliation: Department of Statistics, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27606, USA.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Osborne
authors.affiliation: Tennessee Interventional Associates, Chattanooga, TN 37403, USA.
authors.forename: Blaise
authors.initials: B
authors.lastname: Baxter
mesh_terms: D053587:Arthrometry, Articular; D002081:Buttocks; D003198:Computer Simulation; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Biomodeling; Computational modeling; Piriformis muscle; Stretching