Jan M. Bjordal, PT-MSc,
Faculty of Medicine, University of Bergen, Norway
Christian Couppe, PT, Copenhagen, Denmark

Tendinitis is a common disorder of the musculoskeletal system. Cardinal symptoms from the tendon are pain from increased tension like muscle contraction or stretching and pain on pressure. In an acute stage inflammation is the most common pathophysiological manifestation, while degeneration of the collagen structure is observed in subacute and chronic cases. However, the episodic nature of chronic tendinitis with increased pain after strenous use of the affected tendon, may indicate that inflammation also play a part at this stage. A succesful strategy of treatment should include reduction of inflammation and regeneration of collagen. In the laboratory several experiments have shown that laser treatment may have the potential to achieve both these goals. The findings of the laboratory also shows that these effects are highly dependent on dose which typically conforms with the following figure : 

A synthesis of dose from 4 laboratory trials on inflamed collagen producing cell cultures gives the following dose for optimal reduction of tendon tissue inflammation:

Dose : 3 - 8 J/cm2 
Intensity : 5 - 21 mW/cm2

A synthesis from 10 laboratory trials investigating collagen proliferation gives the following optimal dose for stimulation of tendon regeneration :

Dose : 0.2 - 4 J/cm2 
Intensity : 2 - 10 mW/ cm2


For the treatment of tendinitis an optimal suggested dosage at target location will be : 

Dose : 0.2 - 4 J/cm2 
Intensity : 2 - 10 mW/ cm2

Treatment should be applied daily for at least five days to reduce inflammation, and for at least 10 days to increase collagen production. 

Determination of clinical dose 

The clinical dose depends on several factors such as laser type, depth to target from skin surface, the type of tissue between skinsurface and target location and the volume of injured tissue. 

Characteristics for common tendon disorders

The various tendon locations have different characteristics that affects determination of dose. 

Tendon	Depth to target tendon (mm)	Tendon thickness  (mm)	Typical area of tendon defect (cm2)
Plantar fasciitis	10.0 - 12.0	3.0 – 4.0	0.1  - 0.8
Achilles	1.5 – 3.0	4.5 – 6.0	0.5  – 2.0
Patellar	2.5 – 4.0	5.5 – 8.0	1.0  – 4.0
Epicondylitis	1.5 – 2.5	2.0 – 4.0	0.09 – 0.3
Rotatorcuff	5.0 – 10.0	5.5 -  8.0	0.5   - 1.5

 
Recommendations for optimal laser therapy for common tendon disorders

Infrared lasers (GaAlAs 820/830 nm) are recommended when :

* Power density on skin does not exceed 30 mW/cm2, when treating superficial disorders
* Spot size should not be smaller than 0.5 cm2

                                             Dose on skin:               Number of points
Lateral epicondylitis :       2 J/cm2                          1 - 2
Rotatorcuff :                      2.5 J/cm2                       2 - 4
Patellar :                             8 J/cm2                          3 - 5
Achilles :                            6 J/cm2                          2 - 3

It must be added that there are only two clinical trials showing effect on tendinitis (rotatorcuff) with these lasers and that the dose recommendations for other locations are extrapolations and have not yet been tested clinically.

Infrared pulse lasers (GaAs 904 nm) are recommended when :

* Power density on skin does not exceed 20 mW/cm2, when treating superficial disorders
* Spot size should not be smaller than 0.5 cm2

                                            Dose on skin:                  Number of points
Lateral epicondylitis :       0.5 - 2 J/cm2                   1 - 2
Rotatorcuff :                      0.8 - 6 J/cm2                   2 - 4
Patellar :                             0.8 - 6 J/cm2                   3 - 5
Achilles :                            0.5 - 4 J/cm2                   2 - 3

Clinical results from seven trials suggests that pulse lasers overcome the skin barrier with less need for variation of dose for the different tendon locations.

Red HeNe lasers (632 nm) are only recommended for superficially situated tendon disorders like epicondyitis and paratenonitis of the achilles or patellar tendon. 

Use of He Ne laser on rotatorcuff, deeply situated patellartendinitis (jumpers`knee), plantar facitis or carpal tunnel is not recommended, due to poor penetration of visible red light.

Bergen, July 10th, 2000