Page 124 - Veterinary Laser Therapy in Small Animal Practice

110 Veterinary Laser Therapy in Small Animal Practice

Here are some examples of these calculations. do well without treatment for a couple of months in the
• If your peak power is 18 W and your average warmer season. Others will do best when treated every
power is 12 W, that means you are working with 3–6 weeks for maintenance.
a 66.67% DC. Most musculoskeletal conditions will need longer
• If you know you are operating with a DC of 50% sessions or appointments than wounds, since very
and the screen tells you the peak power is 6 W, often there is more than one body area affected or sore
you know your average power is 3 W. because of overload. Good orthopedic, neurological,
• If you want to know how long your pulses are, and biomechanical exams are essential to plan how
and you are working at 100 Hz with a duty cycle many areas, how often, and how long will it take to
of 30%: 0.3 = 100 Hz × pulse duration, so pulses apply the desired doses over the planned areas. This will
are 0.003 s or 3 ms. With that same DC, if you influence the appointment length, and probably the fee
were pulsing at 2 Hz, those pulses would last 150 that is charged.
ms or 0.15 s.
• Target different cell lines. Osteoblasts seem to 9.2 Laser therapy for fractures and
respond better to lower frequencies, for instance. osteotomies

Therefore, a good strategy seems to combine both Animal models have demonstrated that LT can increase
CW and different pulsing frequencies (as we talked bone mineralization. It stimulates osteoblastic activity
about at length in Chapter 8), which will also avoid a by modulating bone morphogenic factors. The tissue
potential saturation of the biological response. will have a higher number of active osteoblasts and
they will be secreting more collagen matrix, so LT can
9.1.4 How often? help fractures and osteotomies heal faster and produce
a better organized and less exuberant callus. [160, 273–276]
As in wound management, acute conditions need lower This will lead to stronger bone formation; animals
doses but more often initially: daily for 2–3 days, then treated with LT show higher maximum loads at failure
q48h for two to three more treatments, and then twice in bone bending tests. [276, 277] When we use LT in frac-
a week if needed until resolution. And chronic condi- tures, the aim is to enhance biological processes that
tions need higher starting doses but they can be treated contribute to bone healing; we can influence growth
less often, although initially at least three treatments a factor release, vascularization, osteogenic activity, and
week are recommended. inflammation. Research and experience have proven
When dealing with a wound, a full resolution is how important preserving the soft tissue and blood
the clinical expectation, but in many chronic mus- supply is to fracture biology, and LT contributes to this.
culoskeletal problems the goal is to achieve a signifi- If bone grafting is to be used in the fracture repair
cant improvement, then decrease the frequency of procedure, LT can improve bone graft survival. Animal
visits, and find a maintenance regime that will ideally models show that LT improves incorporation at the
prevent relapses and improve the quality of life of the graft–host interface, filling of osteocyte lacunae, and
patient, but will not cure or reverse the basic underly- collagen deposition, while it decreases the inflam-
ing process. These phases are often named induction matory infiltrate in the early postoperative period.
(we achieve the clinical effect with more frequent treat- [275, 278, 279]
ments), transition (we maintain that but decrease the These, together with the anti-inflammatory and
frequency), and maintenance. So after treating three analgesic effects, are the reasons LT can improve frac-
times a week (or q48h), usually for 1–2 weeks, and ture repair and patient’s quality of life. Clinical studies
once an improvement is noted (not before!), LT can (again, very few have been published) in humans show
be delivered twice a week (usually for 2–3 weeks), then that patients achieve better analgesia and functional
once a week for 2–3 weeks. The maintenance regime recovery in closed fractures of the wrist and hand.
after that will vary with the patient. For instance, an [280] Also, LT helps bone formation and healing after
old Labrador with degenerative joint disease (DJD) of mid-palatal suture expansion in children [281] and in
the hip may need to come again more often in the next dogs, [161] and may decrease orthodontic correction
cold/humid season, when his hips hurt more, but may time. [282]

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