A shock wave is a transient pressure disturbance that propagates rapidly in three-dimensional space. It is associated with a sudden rise from ambient pressure to its maximum pressure. A significant tissue effect is cavitation consequent to the negative phase of the wave propagation. The current authors summarize the basic physics of shock waves and the physical parameters involved in assessing the amount of energy delivered to the target tissue and in comparing the various high- and low-energy devices being evaluated clinically for musculoskeletal applications.

Principles of shock wave therapy.

The sources of shockwave generation include electrohydraulic, electromagnetic and piezoelectric principles. Electrohydraulic shockwaves are high-energy acoustic waves generated under water explosion with high voltage electrode. Shockwave in urology (lithotripsy) is primarily used to disintegrate urolithiasis, whereas shockwave in orthopedics (orthotripsy) is not used to disintegrate tissues, rather to induce tissue repair and regeneration. The application of extracorporeal shockwave therapy (ESWT) in musculoskeletal disorders has been around for more than a decade and is primarily used in the treatment of sports related over-use tendinopathies such as proximal plantar fasciitis of the heel, lateral epicondylitis of the elbow, calcific or non-calcific tendonitis of the shoulder and patellar tendinopathy etc. The success rate ranged from 65% to 91%, and the complications were low and negligible. ESWT is also utilized in the treatment of non-union of long bone fracture, avascular necrosis of femoral head, chronic diabetic and non-diabetic ulcers and ischemic heart disease. The vast majority of the published papers showed positive and beneficial effects. FDA (USA) first approved ESWT for the treatment of proximal plantar fasciitis in 2000 and lateral epicondylitis in 2002. ESWT is a novel non-invasive therapeutic modality without surgery or surgical risks, and the clinical application of ESWT steadily increases over the years. This article reviews the current status of ESWT in musculoskeletal disorders.

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Extracorporeal shockwave therapy in musculoskeletal disorders

The purpose of the research was to study the phenomenon of neovascularization at the Achilles tendon-bone junction after low-energy shock wave application. The study was performed on eight mongrel dogs. The control specimens were obtained from the medial one-third of the right Achilles tendon-bone unit before shock wave application. Low-energy shock waves of 1000 impulses at 14 kV (equivalent to 0.18 m J/mm 2 energy flux density) were applied to the right Achilles bone-tendon junction. Biopsies were taken from the middle one-third of the Achilles tendon-bone junction at 4 weeks and from the lateral one-third at 8 weeks, respectively, after shock wave application. The features of microscopic examination included the number of new capillaries and muscularized vessels, the presence and arrangements of myofibroblasts, and the changes in bone. New capillary and muscularized vessels were seen in the study specimens which were obtained in 4 weeks and in 8 weeks after shock wave application, but none were seen in the control specimens before shock wave application. There was a considerable geographic variation in the number of new vessels within the same specimen. Myofibroblasts were not seen in the control specimens. Myofibroblasts with haphazard appearance and intermediate orientation fibers were seen in all study specimens obtained at 4 weeks and predominantly intermediate orientation myofibroblast fibers at 8 weeks. There were no changes in bone matrix, osteocyte activity, and vascularization within the bone. Two pathologists reviewed each specimen and concurrence was achieved in all cases. The results of the study suggested that low-energy shock wave enhanced the phenomenon of neovascularization at the bone-tendon junction in dogs.

Shock wave-enhanced neovascularization at the tendon-bone junction: An experiment in dogs

We report a controlled, prospective study to investigate the effect of treatment by low-energy extracorporeal shock waves on pain in tennis elbow. We assigned at random 100 patients who had had symptoms for more than 12 months to two groups to receive low-energy shock-wave therapy. Group I received a total of 3000 impulses of 0.08 mJ/mm 2 and group II, the control group, 30 impulses. The patients were reviewed after 3, 6 and 24 weeks. There was significant alleviation of pain and improvement of function after treatment in group I in which there was a good or excellent outcome in 48% and an acceptable result in 42% at the final review, compared with 6% and 24%, respectively, in group II.

/pdf/analgesic-effect-of-extracorporeal-shock-wave-therapy-on-4sezzac8bi.pdf

Analgesic effect of extracorporeal shock-wave therapy on chronic tennis elbow

ContextExtracorporeal shock wave therapy (ESWT) is increasingly used for plantar
fasciitis, but limited evidence supports its use.ObjectiveTo determine whether ultrasound-guided ESWT reduces pain and improves
function in patients with plantar fasciitis.DesignDouble-blind, randomized, placebo-controlled trial conducted between
April 1999 and June 2001.SettingParticipants were recruited from the community-based referring physicians
(primary care physicians, rheumatologists, orthopedic surgeons, and sports
physicians) of a radiology group in Melbourne, Australia.ParticipantsWe screened 178 patients and enrolled 166; 160 completed the 15-week
protocol. Entry criteria included age at least 18 years with plantar fasciitis,
defined as heel pain maximal over the plantar aspect of the foot of at least
6 weeks' duration, and an ultrasound-confirmed lesion, defined as thickening
of the origin of the plantar fascia of at least 4 mm, hypoechogenicity, and
alterations in the normal fibrillary pattern.InterventionsPatients were randomly assigned to receive either ultrasound-guided
ESWT given weekly for 3 weeks to a total dose of at least 1000 mJ/mm2 (n = 81), or identical placebo to a total dose of 6.0 mJ/mm2 (n = 85).Main Outcome MeasuresOverall, morning, and activity pain, measured on a visual analog scale;
Maryland Foot Score; walking ability; Short-Form–36 Health Survey (SF-36)
score; and Problem Elicitation Technique score, measured at 6 and 12 weeks
after treatment completion.ResultsAt 6 and 12 weeks, there were significant improvements in overall pain
in both the active group and placebo group (mean [SD] improvement, 18.1 [30.6]
and 19.8 [33.7] at 6 weeks [P = .74 for between-group
difference], and 26.3 [34.8] and 25.7 [34.9] at 12 weeks [P = .99], respectively). Similar improvements in both groups were also
observed for morning and activity pain, walking ability, Maryland Foot Score,
Problem Elicitation Technique, and SF-36. There were no statistically significant
differences in the degree of improvement between treatment groups for any
measured outcomes.ConclusionWe found no evidence to support a beneficial effect on pain, function,
and quality of life of ultrasound-guided ESWT over placebo in patients with
ultrasound-proven plantar fasciitis 6 and 12 weeks following treatment.

/pdf/ultrasound-guided-extracorporeal-shock-wave-therapy-for-4wadcwqr0b.pdf

Ultrasound-guided extracorporeal shock wave therapy for plantar fasciitis: a randomized controlled trial.

The treatment of delayed and nonunion of fractures by a single extracorporeal dose of high energy shock waves generated in a water medium and focused on the fracture site is reported. The shock waves break up sclerotic bone by producing microfissures and numerous bony fragments because of the difference in impedance between bone (and calculi) and soft tissues. Osteogenesis is stimulated and contributed to union in 70 out of 82 fractures within a reasonable time. Treatment was given as an outpatient with regional anaesthesia; there were no side effects or complications.

P. Michailov

Papers

High energy shock waves in the treatment of delayed and nonunion of fractures.