September 2002 Volume 32, No. 9

Vastus Medialis Electrical Stimulation to Improve Lower Extremity Function Following a Lateral Patellar Retinacular Release

Kathleen S. Egan, Alex R. Ward
Study Design: A single-case study design. Objectives: To examine the effect of electrical stimulation of the vastus medialis muscle on stiffness, pain and function for a patient with delayed functional progress following a lateral patellar retinacular release. Background: Five months after an arthroscopic lateral patellar retinacular release, the patient, although highly motivated, had made little progress using routine exercises and taping. Methods and Measures: An electrical stimulation program producing approximately 300 contractions daily of the vastus medialis muscle was implemented. The electrical stimulation applied for 33 of the 36 days was a rectangular and balanced biphasic pulse of 625-µs duration, 70-Hz frequency, 8-second peak on-time, 3-second off-time, 1-second ramp-up, and 0.5-second ramp-down. Objective measures of stair climbing and hopping, together with the subjective measure of therapist-palpated superomedial patella displacement force, were recorded for each treatment visit. Other subjective measures were the patient’s daily recordings of knee pain and stiffness. Results: Patient-reported stiffness reduced rapidly as the actual and cumulative number of daily contractions of the vastus medialis muscle increased. After 8 days of electrical stimulation, the patient was able to ascend stairs unassisted and after another 21 days to hop unsupported. Conclusions: Stiffness rapidly reduced and function started to improve once the electrical stimulation program was implemented. Recovery during the 36 days of treatment with electrical stimulation was greater than during the previous 5 months using other methods. Compliance was not an issue, nor was muscle soreness.

J Orthop Sports Phys Ther. 2002; 32(9):437–446.

Keywords: knee, patella, patellofemoral, quadriceps

Failure to Detect Dexamethasone Phosphate in the Local Venous Blood Postcathodic Iontophoresis in Humans

Kenneth E. Ferslew, Catherine L. Gabaree, Michele F. Mayo, Peter C. Panus, Michael A. Smutok
Study Design: A single-blind, 2-factor (4 treatments by 8 time points) repeated-measures study design.

Objective:To analytically determine dexamethasone and dexamethasone phosphate concentrations in plasma derived from proximal effluent venous blood, following cathodic iontophoresis.

Methods and Measures: Six volunteers received the following dexamethasone phosphate (2.5 ml, 4 mg/ml) treatments to their wrists on separate occasions: cathodic iontophoresis (4 mA, 10 minutes or 4 mA, 20 minutes), passive application (10 or 20 minutes). Plasma samples from the ipsilateral antecubital vein were obtained 10 minutes prior to and half way through the treatment (5 or 10 minutes), at the end of the treatment (10 or 20 minutes), and posttreatment (15, 30, 60, 90, and 120 minutes). The present investigation examined: (1) the sensitivity and linearity of extraction and analysis of dexamethasone and dexamethasone phosphate; (2) the necessity for determining both; and (3) the plasma levels from proximal effluent venous blood following cathodic iontophoresis. Results: The aggregate (n = 18) of the 6-point standard curves were linear for dexamethasone (r > 0.974) and dexamethasone

phosphate (r > 0.829). In vitro dephosphorylation of dexamethasone phosphate to dexamethasone occurred in plasma at 37�C and during freeze-thaw. Measurable dexamethasone or dexamethasone phosphate concentrations were absent at all time points and under all conditions in the human subjects.

Conclusions: These results demonstrate the sensitivity of the current assay and the need for evaluating both forms of the drug, as in vitro dephosphorylation results in the presence of dexamethasone and dexamethasone phosphate in samples. Absence of measurable dexamethasone or dexamethasone phosphate in the proximal effluent venous blood may require re-evaluation of the extent of drug delivery during the clinical iontophoresis of dexamethasone phosphate.

J Orthop Sports Phys Ther. 2002; 32(9):461�468.

Keywords: anti-inflammatory agents, cutaneous administration, pharmacokinetics, tissue distribution

Kinematics of the Double-Leg-Lowering Test for Abdominal Muscle Strength

Richard W. Bohannon, Michael J. Dewberry, Julie M. Murray, David Tiberio, Chad M. Zannotti
Study Design: Prospective descriptive study.

Objective:To investigate the kinematics of the double-leg-lowering (DLL) test of abdominal muscle strength.

Background: Adequate strength of the abdominal muscles is necessary for many household, occupational, and sports activities. Therapists, therefore, need valid measures of abdominal muscle strength.

Methods and Measures: A convenience sample of 17 subjects (7 women, 10 men) was tested. Using reflective spheres to identify specific body segments, subjects were videotaped while performing DLL under 2 conditions: attempting (controlled) prevention of anterior pelvic tilting versus not attempting (uncontrolled) prevention of anterior pelvic tilting. Videotape was analyzed using the PEAK 5 2-dimensional system.

Results: The pelvis tilted anteriorly by the time the extremities were lowered a mean 3.6�, regardless of condition. No significant difference in anterior pelvic tilting was associated with the 2 DLL conditions (F = 2.95, P = 0.105) but pelvic tilting did increase significantly as the lower extremities were lowered from vertical (F = 98.41, P < 0.001).

Conclusions: There appears to be a natural tendency for the pelvis to tilt anteriorly from very early in the DLL maneuver. As healthy young subjects do not appear able to prevent the tilting, the scoring system associated with the DLL test should be questioned.

J Orthop Sports Phys Ther. 2002; 32(9):432�436.

Keywords: examination, lower extremity, pelvis, physical therapy, trunk

Relationship Between Mechanical Factors and Incidence of Low Back Pain

Amir Massoud Arab, Mohammad Reza Nourbakhsh
Study Design: A multifactorial cross-sectional nonexperimental design.

Objectives: To collectively investigate the association among 17 mechanical factors and occurrence of low back pain (LBP).

Background: Several physical characteristics, based on assumptions, clinical findings, and scientific experiments, have been associated with the development of LBP. Controversy exists regarding the degree of association between some of these physical characteristics and LBP. Information regarding the degree of association of each factor to LBP is needed for effective prevention and appropriate treatment strategies.

Methods and Measures: A total of 600 subjects participated in this study. Subjects were categorized into 4 groups: asymptomatic men (n = 150, age [mean � SD] = 43 � 15 years), asymptomatic women (n = 150, age [mean � SD] = 43 � 13 years), men with LBP (n = 150, age [mean � SD] = 43 � 14 years), and women with LBP (n = 150, age [mean � SD] = 43 � 13 years). Seventeen physical characteristics were measured in each group and the relative association of each characteristic with LBP was assessed.

Results: Among all the factors tested, endurance of the back extensor muscles had the highest association with LBP. Other factors such as the length of the back extensor muscles, and the strength of the hip flexor, hip adductor, and abdominal muscles also had a significant association with LBP.

Conclusion: It appears that muscle endurance and weakness are associated with LBP and that structural factors such as the size of the lumbar lordosis, pelvic tilt, leg length discrepancy, and the length of abdominal, hamstring, and iliopsoas muscles are not associated with the occurrence of LBP. J Orthop Sports Phys Ther. 2002; 32(9):447�460.

Keywords: back extensor endurance, low back pain, lumbar lordosis, muscle length, muscle strength

JOSPT--This Editor’s Perspective

Guy G. Simoneau