J Orthop Sports Phys Ther 1993;17(5):247-251.

Key Words: ultrasound, conducting mediums, tissue temperature

Study Design: A randomized, counterbalanced 2×3×5 repeated-measures design. Objective: To compare changes in hamstring flexibility after treatments of pulsed shortwave diathermy and prolonged stretch, sham diathermy and prolonged stretch, and control. Background: Heat and stretch techniques have been touted for years. To date, the effect of shortwave diathermy and hamstring stretching has not been studied. Because diathermy heats a large area and penetrates deep into the muscle, use of this device prior to or during hamstring stretching may increase flexibility. Methods and Measures: Thirty college-age students (mean age, 21.5 years) with tight hamstrings (inability to achieve greater than 160° knee extension at 90° hip flexion) participated. Subjects were assigned to 1 of 3 groups: diathermy and stretch, sham diathermy and stretch, and control). Range of motion was recorded before and after each treatment for 5 days and on day 8. A straight leg-raise stretch was performed using a mechanical apparatus. Subjects in the diathermy-and-stretch group received 10 minutes of diathermy (distal hamstrings) followed by 5 minutes of simultaneous diathermy and stretch, followed by 5 minutes of stretching only. Subjects in the sham-diathermy-and-stretch group followed the same protocol, but with the diathermy unit turned off. Subjects in the control group lay on the table for 20 minutes. Data were analyzed using an ANOVA and post hoc t tests. Results: Mean (± pooled SE) increases in knee extension after 5 days were 15.8° ± 2.2° for the diathermy-and-stretch group, 5.2° ± 2.2° for the sham-diathermy-and-stretch group, and –0.3° ± 2.2° for the control group. Seventy-two hours after the last treatment, the diathermy-and-stretch group lost 1.9° ± 2.2°, the sham-diathermy-and-stretch group lost 3.0° ± 2.2°, and the control group changed –0.4° ± 2.2°. Conclusion: These results suggest that hamstring flexibility can be greatly improved when shortwave diathermy is used in conjunction with prolonged stretching.

J Orthop Sports Phys Ther. 2004;34(1):13-20. doi:10.2519/jospt.2004.0978

Key Words: heat, muscle, range of motion, thigh

Study Design: A repeated-measure crossover design was used. The independent variable was the type of ultrasound (pulsed or continuous) and the dependent variable was intramuscular temperature. Objective: To compare changes in intramuscular temperature resulting from the use of pulsed ultrasound versus continuous ultrasound with an equivalent spatial average temporal average (SATA) intensity. Background: There is a lack of research on the heat-generating capabilities of pulsed ultrasound within human muscle. Methods and Measures: The subjects were 16 healthy volunteers (mean age ± SD, 21.3 ± 2.5 years). Each subject was treated with pulsed ultrasound (3 MHz, 1.0 W/cm ₂, 50% duty cycle, for 10 minutes) and continuous ultrasound (3 MHz, 0.5 W/cm ₂, for 10 minutes) during a single testing session. Tissue temperature returned to baseline and stabilized between treatments and treatment order was randomized. Tissue temperature was measured every 30 seconds using a 26-gauge needle microprobe inserted at a depth of 2 cm in the left medial gastrocnemius muscle. Data were analyzed using a linear mixed model. Results: Treatment with continuous ultrasound produced a mean (±SD) temperature increase of 2.8°C ± 0.8°C above baseline. Treatment with pulsed ultrasound produced a mean (±SD) temperature increase of 2.8°C ± 0.7°C above baseline. Statistical analysis revealed no significant differences in either the extent or rate of temperature increases between the 2 modes of ultrasound application. Conclusion: Pulsed ultrasound (3 MHz, 1.0 W/cm ₂, 50% duty cycle, for 10 minutes) produces similar intramuscular temperature increases as continuous ultrasound (3 MHz, 0.5 W/cm₂, for 10 minutes) at a 2-cm depth in the human gastrocnemius. Spatial average temporal average intensity is an important consideration when selecting pulsed ultrasound parameters intended to deliver nonthermal effects.

J Orthop Sports Phys Ther. 2004;34(7):395-401. doi:10.2519/jospt.2004.1363 

Key Words: heat, physical agents, spatial average temporal average intensity

Study Design: Prospective, randomized, crossover design. Objectives: To compare the effectiveness of the Johnson & Johnson Back Plaster, the ABC Warme-Pflaster, and the ThermaCare HeatWrap on skin and paraspinal muscle temperature. Also, to compare the subjects’ heat perception for the 3 products. Background: Heat therapy is a common treatment for low back pain and disability. There are a number of products on the market that are suggested to relieve low back pain by providing warmth to the back; however, their effectiveness for increasing tissue temperature compared with heat sensation has not been tested. Methods and Measures: To measure paraspinal muscle temperature, 1 thermocouple monofilament was inserted into the paraspinal muscle 2 cm from the skin surface at the L3 level using a 20-gauge 1.25-in (3.15-cm) sterile catheter. To measure skin interface temperature, 2 thermocouples were placed on the skin at distances of 5 cm and 7 cm from the insertion site. The Isothermex was used to record temperatures to the nearest 0.1°C for 120 minutes. The subjects also rated heat perception using a 10-cm visual analog scale at 0, 30, 60, 90, and 120 minutes. Analysis of covariance models was used for statistical analysis. Results: There was a significant product × time interaction (F_14,231 = 3.77, P<.0001) at the intramuscular site, but there was not a significant product × time interaction (F_14,231 = 1.03, P = .4228) at the skin site. Both the main effects for product (F_2,33 = 41.59, P<.0001) and time (F_3,51 = 19.02, P<.0001) were significant for the visual analog scale data. The ThermaCare HeatWrap produced significant increases in both skin and intramuscular temperatures with less heat sensation. The Johnson & Johnson Back Plaster and the ABC Warme-Pflaster increased temperature at the skin surface and provided the greatest heat sensations, but they did not provide intramuscular heat. Conclusions: The ThermaCare HeatWrap is more effective at increasing temperature at a 2-cm depth with less perceived heat compared to the Johnson & Johnson Back Plaster and the ABC Warme-Pflaster. The latter 2 products provide a sensation of heat but do not actually provide a muscle temperature change at a depth of 2 cm.

J Orthop Sports Phys Ther. 2004;34(9):549-558. doi:10.2519/jospt.2004.1168

Key Words: heat, low back, physical agents, temperature

Study Design: A time series design was used, with the dependent variable being gastrocnemius muscle temperature at a depth of 3 cm. Objectives: To determine the rate of temperature rise and the rate of post-treatment temperature decline in skeletal muscle following the application of pulsed short-wave diathermy (PSWD). Background: Data on PSWD rate and longevity of heating are 20 years old and outdated. With the recent introduction of advanced diathermy equipment, results of our study would provide clinicians with much needed information regarding treatment duration. Methods and Measures: A 23-gauge thermistor was inserted into the center of the medial head of the anesthetized gastrocnemius muscle, 3 cm below the skin's surface of 20 subjects. The PSWD (27.12 MHz frequency) was applied using the following parameters: 800 bursts per second; 400 usecond burst duration; 850 usecond interburst interval; with a peak root mean square (RMS) amplitude of 150 W per burst and an average RMS output of 48 W. Temperature changes were documented every 5 minutes during the treatment and additionally at 5 and 10 minutes following treatment. Results: The average baseline and peak temperatures were 35.84 ± 0.93°C and 39.80 ± 0.83°C, respectively. Mean temperature increases were: 1.36 ± 0.90°C (5 min); 2.87 ± 1.44°C (10 min); 3.78 ± 1.19°C (15 min); 3.49 ± 1.13°C (20 min). After the treatment terminated, intramuscular temperature dropped 0.97 ± 0.68°C in 5 minutes and 1.78 ± 0.69° in 10 minutes. Conclusions: PSWD is an effective modality if temperature elevation of deep tissue over a large area is the clinical objective.

J Orthop Sports Phys Ther. 1999;29(1):13-22.

Key Words: diathermy, heat, ultrasound

The anterior drawer and Lachman tests are frequently used for determining anterior cruciate ligament (ACL) instability. The Lachman test is considered to be the most accurate, yet it is difficult to perform on a large person, especially by an examiner with small hands. One procedure, the alternate Lachman test, has been used with some success by examiners who have difficulty performing the Lachman test. The purpose of this study was to compare these 3 manual tests with respect to predicting ACL stability. These findings were compared with those of the KT-1000 knee arthrometer. Seventy-four subjects (x¯ age = 22 years) volunteered for the study. Girth measurements were recorded for each subject at 8 cm above and below the midpoint of the patella. An examiner with small hands (21-cm span) performed each of the 3 tests on both knees of the subjects and then recorded which knee he believed was the more lax of the 2 with respect to each test. Another examiner then tested each subject's knees with the KT-1000. A log-linear model with terms for manual test type, category, and thigh girth was used for statistical analysis. The alternate Lachman test significantly outperformed the other 2 tests. Subjects with >2.5 mm bilateral laxity difference were correctly evaluated 100% of the time using the alternate Lachman test. In subjects with large thigh girth (>43 cm), 1) the alternate Lachman test was correct 78% of the time; 2) the anterior drawer test was correct 59% of the time; and 3) the Lachman test produced only 28% correct examinations. Based upon these results, the alternate Lachman test should be included in the regimen of manual ACL tests, especially for athletes with large thigh circumference or when performed by examiners with small hands.

J Orthop Sports Phys Ther. 1995;22(6):263-266.

Key Words: knee, anterior cruciate ligament, instability, examiner proficiency

Therapeutic ultrasound can be a very effective treatment modality when used correctly in the treatment of musculoskeletal conditions and wound healing. However, many protocols for the administration of ultrasound have not been scientifically tested. The purpose of this study was to measure muscle temperature changes during a frequently used protocol, ie., preicing prior to ultrasound application. A 23-gauge hypodermic needle microprobe was inserted 5 cm deep into the medial aspect of the anesthetized triceps surae muscle of 16 subjects. Two groups consisting of 8 subjects each were tested for temperature changes during: a) ultrasound treatment on precooled tissue or b) ultrasound with no preceding treatment. Each treatment consisted of 10 minutes of continuous ultrasound delivered topically at 1.5 watts/cm2. A significant difference between the 2 treatment methods was measured (F = 19.06, p < 0.01). Ultrasound alone increased tissue temperature an average of 4.0 ± .83°C, whereas ultrasound preceded by 5 minutes of ice increased tissue temperature only 1.8 ± 1.0°C above original baseline level. At a depth of 5 cm, ultrasound preceded by ice treatment yielded little or no thermal benefits.

J Orthop Sports Phys Ther. 1995;21(3):153-157.

Key Words: ultrasound, muscle temperature, cryotherapy

To achieve the thermal effects of ultrasound, the tissue temperature must be raised from 1 to = 4°C, depending on the desired outcome of the treatment. In the past 25 years, there have been no in vivo studies that have measured rate of change in temperature during 1-MHz ultrasound treatments, and none have ever been performed with the 3-MHz frequency. Thus, we are left to pure speculation regarding how long to administer an ultrasound treatment. We performed this study to plot the rate of temperature increase during ultrasound treatments delivered at various intensities and frequencies. We inserted two 23-gauge thermistors into each subjects' medial triceps surae at the following depths: 1 MHz at depths of 2.5 and 5.0 cm (12 subjects) and 3 MHz at depths of .8 and 1.6 cm (12 subjects). Each subject received a total of 4 10-minute treatments, 1 each at 0.5, 1.0, 1.5, and 2.0 W/cm2, and temperature was measured every 30 seconds. No significant difference was found in the rate of heating at the 2 depths (p = .987) within the same frequency and dose levels. The 3-MHz frequency heated significantly faster than the 1-MHz frequency at all doses tested (p < .001). On average, the rate of temperature increase per minute at the 2 depths of the 1-MHz frequency was: 0.04°C at 0.5 W/cm2; 0.16°C at 1.0 W/cm2; 0.33°C at 1.5 W/cm2; and 0.38°C at 2.0 W/cm2. The rate of temperature increase per minute at the 2 depths of the 3-MHz frequency was: 0.3°C at .5 W/cm2; 0.58°C at 1.0 W/cm2; 0.89°C at 1.5 W/cm2; and 1.4°C at 2.0 W/cm2. The results of this research should enable clinicians to choose the correct frequency, intensity, and treatment time when using thermal ultrasound.

J Orthop Sports Phys Ther. 1995;22(4):142-150.

Key Words: ultrasound, tissue, temperature

Study Design: Case series.
Background: Traditionally, all forms of diathermy have been contraindicated over metal implants. There is a lack of research-based evidence for harm regarding the use of pulsed shortwave diathermy (PSWD) over orthopaedic metal implants. Because PSWD is an effective modality for deep heating, we investigated whether ankle range of motion (ROM) could improve with the cautious use of PSWD and joint mobilizations, despite orthopaedic metal implants being in the treatment field.
Case Descriptions: Four subjects presented with decreased ankle ROM due to extensive fractures from traumatic injuries. All subjects were postsurgical, with several internal fixation devices. Subjects previously received rehabilitation therapy involving joint mobilizations, therapeutic exercises, moist heat, and ice, but continued to lack 15° to 23° of ankle dorsiflexion. The Human Subjects Review Board of Brigham Young University approved the methods of this case series. Subjects gave written informed consent. Initial dorsiflexion active ROM for each patient was –3°, 0°, 8°, and 5°, respectively. Treatment regime consisted of PSWD to the ankle for 20 minutes at 27.12 MHz, 800 pps, 400 microseconds (48 W). Immediately after PSWD, mobilizations were administered to the joints of the ankle and foot. Ice was applied posttreatment.
Outcomes: Dorsiflexion improved 15°, 15°, 10°, and 14°, respectively, after 8 or 13 visits. All patients returned to normal activities with functional ROM in all planes. Follow-up 4 to 6 weeks later indicated that the subjects maintained 78% to 100% of their dorsiflexion. No discomfort, pain, or burning was reported during or after treatment. No negative effects were reported during the short-term follow-up.
Discussion: When applied with appropriate caution, we propose PSWD (48 W) may be an appropriate adjunct to joint mobilizations to increase ROM in peripheral joints, despite implanted metal. We continue to advise caution when applying diathermy with machines other than the Megapulse II. Further research is needed to determine the safety parameters of other diathermy machines. As a final caution, we advise that diathermy not be used in the presence of a cardiac pacemaker or neurostimulator.

J Orthop Sports Phys Ther. 2006;36(9):669-677. doi:10.2519/ jospt.2006.2198

The conflict of interest of the original article was amended in the February 2010 Errata, and the article PDF with the Errata page included is provided here. Please see: February 2010 Errata

Key Words: heat, internal fixation, modalities, physical agents, shortwave diathermy