Laser and Growth Plates
07 Jan 2018
Not so long ago we had a surgeon state that all of the lasering we had been doing to one of his patients had caused the growth plates to close prematurely. It was a young dog, for whom we were providing pre-hab for a torn ACL while we waited for growth plates to close in order for a TPLO to be performed.
So, 1) feeling horrible that this could be true, and 2) wanting to combat the accusation, I went to my trusty friend PubMed to see what she had to say. (P.S. I figure Pubmed is a ‘she’. No reason, just because…)
I found three recent papers that looked at growth plate closure and laser therapy.
The first paper:
Scientific World Journal. 2012;2012:231723. doi: 10.1100/2012/231723. Epub 2012 Apr 30.
The effects of low-level laser therapy, 670 nm, on epiphyseal growth in rats.
de Andrade AR1, Meireles A, Artifon EL, Brancalhão RM, Ferreira JR, Bertolini GR.
The longitudinal growth of long bones is attributed to epiphyseal growth. However, the effects of low-level laser therapy (LLLT) in such structures has still not been studied extensively in the literature. Therefore, the aim of this study was to evaluate the use of LLLT, 670 nm, at three different doses on the epiphyseal growth of the right tibia of rats. Twenty-one Wistar rats, aged four weeks, were subjected to the application of LLLT, with dosage according to the group (G4: were submitted to the application of 4 J/cm(2); G8: were submitted to the application of 8 J/cm(2); G16: were submitted to the application of 16 J/cm(2)). After completion of protocol they were kept until they were 14 weeks of age and then submitted to a radiological examination (evaluation of limb length) and euthanised. The histological analysis of the growth plates (total thickness and hypertrophic and proliferative zones) was then performed. Comparisons were made with the untreated left tibia. No differences were observed in any of the reviews (radiological and histological), when comparing the right sides (treated) to the left (untreated). It was concluded that the treatment with LLLT within the parameters used caused changes neither in areas of the epiphyseal cartilage nor in the final length of limbs.
Thoughts: So this is a 670nm laser. It doesn’t penetrate much past 0.5cm, and this wavelength is better targeted at skin lesions. Nevertheless, it did not impact the growth plates.
The second study:
Photomed Laser Surg. 2010 Aug;28(4):527-32. doi: 10.1089/pho.2009.2572.
Effect of GaAlAs laser irradiation on the epiphyseal cartilage of rats.
Cressoni MD1, Giusti HH, Pião AC, de Paiva Carvalho RL, Anaruma CA, Casarotto RA.
OBJECTIVE:
To study the effect of an 830-nm gallium-aluminum-arsenic (GaAlAs) diode laser at two different energy densities (5 and 15 J/cm(2)) on the epiphyseal cartilage of rats by evaluating bone length and the number of chondrocytes and thickness of each zone of the epiphyseal cartilage.
BACKGROUND DATA:
Few studies have been conducted on the effects of low-level laser therapy on the epiphyseal cartilage at different irradiation doses.
MATERIALS AND METHODS:
A total of 30 male Wistar rats with 23 days of age and weighing 90 g on average were randomly divided into 3 groups: control group (CG, no stimulation), G5 group (energy density, 5 J/cm(2)), and G15 group (energy density, 15 J/cm(2)). Laser treatment sessions were administered every other day for a total of 10 sessions. The animals were killed 24 h after the last treatment session. Histological slides of the epiphyseal cartilage were stained with hematoxylin-eosin (HE), photographed with a Zeiss photomicroscope, and subjected to histometric and histological analyses. Statistical analysis was performed using one-way analysis of variance followed by Tukey's post hoc test. All statistical tests were performed at a significance level of 0.05.
RESULTS:
Histological analysis and x-ray radiographs revealed an increase in thickness of the epiphyseal cartilage and in the number of chondrocytes in the G5 and G15 groups.
CONCLUSION:
The 830-nm GaAlAs diode laser, within the parameters used in this study, induced changes in the thickness of the epiphyseal cartilage and increased the number of chondrocytes, but this was not sufficient to induce changes in bone length.
Thoughts: So this is a more appropriate laser wavelength, and more closely related to what we use in clinical practice. The use (every second day) is also a bit closer to clinical practice, albeit a more concentrated schedule than what clinical practice employs. There were cartilage changes (but the same changes occur with exercise and cartilage loading). The downside of this study is that it only last for 10 days and the animals were evaluated immediately after the 10-day protocol. A long term study would have been interesting.
The last paper:
Acta Cir Bras. 2012 Feb;27(2):117-22.
Low-level laser on femoral growth plate in rats.
Oliveira SP1, Rahal SC, Pereira EJ, Bersano PR, Vieira Fde A, Padovani CR.
PURPOSE:
To determine the influence of low-level laser therapy on femoral growth plate in rats.
METHODS:
Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm(2). The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis.
RESULTS:
In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days.
CONCLUSION:
The low-level laser therapy negatively influenced the distal femoral growth plate.
Thoughts: This is a very interesting study, and it does indicate that DAILY use of laser at a more appropriate therapeutic dose and wavelength, caused a reduction in limb growth. This study was extended for longer, that study #2, which may explain why study #2 saw no effect.
Overall thoughts: We do likely have to be cautious with being overzealous about lasering over active growth plates. Obviously, it would be great to see a study that would look at weekly or even twice-weekly lasering over an active growth plate, and extend the study for longer. All in all, we don’t have a definitive answer for what to do in clinical practice. I would lean towards being ‘okay’ to laser on a weekly basis as need be, on a risk vs reward evaluation, but that’s me!
