Extract
This report, derived from a symposium presented at the Annual
Meeting of the American Orthopaedic Association in 2001, takes a
critical look at the use of lasers and radiofrequency devices in orthopaedic
surgery in an attempt to place their application in perspective relative
to the well-known techniques presently used and accepted by orthopaedists.
Such questions as "Are these devices useful enough to justify a
wider application in orthopaedics?" and "Are they worth the time
and money that it would require to learn about and use them?" will
be addressed.
This report, derived from a symposium presented at the Annual
Meeting of the American Orthopaedic Association in 2001, takes a
critical look at the use of lasers and radiofrequency devices in orthopaedic
surgery in an attempt to place their application in perspective relative
to the well-known techniques presently used and accepted by orthopaedists.
Such questions as "Are these devices useful enough to justify a
wider application in orthopaedics?" and "Are they worth the time
and money that it would require to learn about and use them?" will
be addressed.
Laser and radiofrequency technologies are compared with the technologies
that have become well established for a given clinical application.
In addition, the current report points out the presence or absence
of clinical evidence to support the theory that lasers and radiofrequency
are better and more cost-effective than other technologies, and
it notes the laser and radiofrequency applications that have been developed
primarily on the basis of laboratory data rather than clinical evidence.
The basic physics of lasers and radiofrequency, their use in
spine surgery and arthroscopy, their potential for joint stabilization
(capsular shrinkage), and their possible future applications in
the area of tissue-welding and meniscal repair are summarized. It
is hoped that this overview will provide orthopaedic surgeons with
insight into these technologies and will give them the basis for
deciding whether to accept, reject, or continue to investigate them.
Lasers
The generation of light amplified by stimulated emission of radiation
(laser) requires (1) a power source, such as a flash lamp or electric
coil, (2) a laser medium, such as a crystal or gas, and (3) two
mirrors at each end of the medium, one of which is fully reflective and
the other, partially reflective. Stimulation of the laser medium
by the power source energizes and displaces the electrons in the
atoms of the medium, producing a population inversion of the atoms
and the generation of photons of light. The mirrors capture the
light and reflect it back and forth until the light has sufficient
strength to pass through the partially reflective mirror and emerge
as a laser beam. The laser has the qualities of coherence, collimation,
and monochromaticity, meaning that the light is nondivergent, the rays
of light move in the same phase, and the light has only one wavelength in
the electromagnetic spectrum.
The wavelength of the light depends on the medium. Carbon dioxide,
for example, generates light in the 10.66-μm range. A ruby
crystal generates red light at about 0.840 μm, and a crystal
of yttrium, aluminum, and garnet doped with neodymium (Nd:YAG) produces
light in the near infrared with a 1.06-μm wavelength. The
holmium laser produces light in the mid-infrared, with a 2.1-μm
wavelength, which emanates from a crystal of yttrium, aluminum,
and garnet doped with holmium (Ho:YAG).
In orthopaedics, the effectiveness of the laser depends on the
ability of nonpigmented water-containing tissue to absorb light.
Since visible light passes through water with little or no absorption
of its energy, visible light lasers, such as the ruby, KTP (potassium-titanyl-phosphate),
helium-neon, and argon lasers, cannot effectively ablate tissues
unless a vital dye is placed on or in the tissues. The dye absorbs
the laser energy to create the desired result, but the water, in
effect, does not see the laser beam. The CO2, erbium:YAG (Er:YAG),
and the Ho:YAG lasers are absorbed by water and can be used in orthopaedic
surgery. The Ho:YAG is the least effective of these three lasers, and
some thermal injury of tissue occurs with its use.
Radiofrequency
Surgery with radiofrequency utilizes alternating current, which
passes through the patient's tissues. The tissues provide the impedance
necessary to produce heat as electrons overcome the resistance in
the tissues, and the patient's body, therefore, becomes part of
an electrical circuit. Alternating current operating at about 60
Hz with low voltage causes muscular contraction. At very high voltages,
a 60-Hz alternating current can cause electrocution. If, however,
the current alternates at a much higher frequency, for example,
at 330,000 cycles per second (330 kHz), the electrical energy can
pass harmlessly through the patient's body. Surgical applications
of high-frequency alternating current require the use of a small
active electrode and a large grounding electrode at a site removed from
the surgical field. The small active electrode and the large grounding
electrode allow a high-current density to develop at the former
and a low-current density to develop at the latter. Since the amount
of heat developed by high-frequency alternating current increases by
the square of the current density, the tissues beneath the tip of
the active electrode can become hot enough to vaporize the water
they contain, thereby producing a cutting or ablating effect. The
current density dissipates rapidly away from the tip of the active
electrode and becomes insufficient to heat the patient's tissues
above the level that cannot be disseminated by circulating blood.
The surgeon can modify the effect of the alternating current by switching
from a cutting to a coagulating mode by varying the current waveform
and power. If the current remains 100% on and at a relatively low
voltage, it will cut and ablate tissue. When it is 6% on and at
a relatively high voltage, the current will heat tissues to the
point of denaturation, thereby sealing small arteries and veins
or shrinking and coagulating tissue.
Radiofrequency devices generally have either a monopolar or a
bipolar configuration. Monopolar radiofrequency devices necessitate
an active electrode within the surgical probe and a passive return
electrode at a place on the patient's body, at a distance from the surgical
site. A bipolar probe contains both the active and the return electrodes within
the surgical probe.
Percutaneous Laser Disc Decompression
Ascher et al.
1
, Choy and Ngeow
2
, Liebler
3
, and others have used lasers percutaneously since 1986 in the treatment
of thousands of patients who had lumbar disc degeneration. Their
technique consisted of the placement of an 18-gauge needle into
the degenerated disc, inserting it through a 1-mm laser fiber, and slowly
applying 1200 J of energy from an Nd:YAG laser with a wavelength
of 1.06 μm. Choy and Ngeow
2
determined that the 1200 J of energy produced a small defect in
the nucleus pulposus, which, in turn, produced a disproportionately
large drop in intradiscal pressure because of the bulk modulus effect.
In 1989 and 1998, Ascher et al. and Choy and Ngeow reported that
75% to 80% of their patients had fair-to-good relief of pain in
the back and lower extremities. In the early 1990s, other investigators
evaluated the effects of the Ho:YAG laser on disc tissue in a series
of in vivo and in vitro studies
4
. The results of the clinical application of the Ho:YAG laser were
about the same as those reported with use of the Nd:YAG laser
4
. These procedures have limited application, and, like chemonucleolysis
and automated percutaneous lumbar discectomy, they do not have the
capability to remove disc material from the spinal canal. Thus,
patients with sequestered or severely extruded disc fragments should
not opt for this type of procedure. In addition, patients who have early
disc degeneration with or without mild dorsal protrusion usually
get well without this level of intervention.
Considering the large number of procedures that have been reported,
the cavitation of the nucleus pulposus by lasers apparently carries
relatively little risk. A literature search identified one patient
who had Salmonella discitis
5
, several patients with end-plate fragmentation
6
, and one patient in whom a sequestered disc had to be removed through
a laminectomy
7
. Some anecdotal reports have described dural leaks, small-bowel
perforations, and nerve-root injuries, but these complications appear
to have been errors in needle placement and were not directly related
to the laser.
Endoscopic Laser-Assisted Disc Surgery
Recognizing the limitations of percutaneous intradiscal surgery
with or without a laser, some surgeons have worked toward the development
of laser-assisted endoscopic techniques. Yeung
8
and Casper et al.
9
in the United States, Knight et al.
10
and Seibert
11
in Europe, and others described similar techniques in reports on
their early results with foraminal laser endoscopic disc ablation
and endoscopic laser foraminotomy. For patients who have had failure
of conservative treatment and have a diagnosis of a far lateral
or foraminal disc extrusion or sequestration or exit-zone foraminal
stenosis that has been established on the basis of appropriate studies,
these operations may have some value. The outpatient procedures
require a small posterolateral incision with the patient under local
anesthesia with anesthesia standby. Fluoroscopic control permits accurate
placement of a guide-wire in the posterolateral portion of the nucleus pulposus.
Cannulae are railroaded sequentially over the guide-wire to permit
the introduction of the endoscope. Irrigation with saline solution
at a rate of 40 to 60 mL per minute with a passive outflow maintains
sufficient tissue distension to allow visualization of the herniated
disc material, the foraminal space, and the exiting nerve root.
Large disc fragments, which may be difficult to withdraw mechanically
through the 5-mm endoscope, can be ablated with either a side-firing
or straight-ahead-firing laser probe. Disc removal continues until
the exiting and traversing roots can be clearly visualized and there
is no longer compression by disc or anulus fibrosus.
Surgeons who perform this procedure report success rates, according
to evaluation standards such as the McNab criteria and various pain
questionnaires, on a par with those of open procedures. They note,
however, that these techniques have a "learning curve" and it takes
some time to become skillful in their use.
Intradiscal Electrothermal Anuloplasty (IDET)
In addition, the thermal energy used in the procedure may coagulate
the nociceptive pain-sensing neural fibers that innervate the anulus
fibrosus and the posterior longitudinal ligament, thereby eliminating
their potential for transmitting pain signals into the central nervous
system. Saal and Saal, who devised the procedure, have not assessed
the relative contribution of collagen modification and remodeling versus
denervation as factors that have led to the observed clinical improvement
in their patients. They also have not evaluated the biomechanical changes
that might occur nor have they studied the long-term effects of
the procedure on the tissue.
These issues were addressed in a cadaveric study performed by
Kleinstueck et al.
14
. They found a consistent pattern of increased motion and decreased
stiffness after intradiscal electrothermal therapy, with no apparent
alteration of anular architecture around the catheter site. They
concluded that temperatures developed during intradiscal electrothermal
therapy are insufficient to alter collagen architecture or to stiffen
the treated motion segment acutely.
The Oratec Corporation (Menlo Park, California), which manufactures
the device (Spine CATH intradiscal catheter), reported that, at
the time of writing (a little over two years since the procedure
was first reported), approximately 22,000 patients had been managed
with it. Studies published in peer-reviewed journals and presented
at national meetings have documented the outcome in approximately
600 patients. The findings have been consistent, with 72% to 75%
of the patients demonstrating improvement in physical function and bodily
pain scores and 60% noting improvement in sitting tolerance and walking
ability. Surgeons and others performing the intradiscal electrothermal
procedure have reported few complications. However, there have been technical
problems, including catheter breakage within the disc space and
difficulty in navigating the catheter into the correct position.
Forty percent of the procedures require bilateral needle insertion
to completely treat the posterior aspect of the anulus fibrosus.
In addition, extradiscal migration of the catheter has caused problems
and, although a fair-to-poor result does not rank as a complication,
up to 5.7% of the patients in one series
15
required spinal arthrodesis. Infections have occurred very infrequently,
and vertebral end-plate changes or fragmentation have not been described
15,16
. The long-term consequences of the procedure are currently unknown.
Meniscal Surgery
The use of lasers in arthroscopic meniscal repair has been described
in several reports, which also analyzed the effects of different
wavelengths and examined the extent of thermal penetration into the
meniscal tissue
17-20
. The laser was shown to be a good tool for smoothing and contouring
the rough surfaces of meniscal tears. It also demonstrated a minimal
amount of tissue penetration, as the most commonly used clinical
laser, the Ho:YAG, caused <1 mm of thermal penetration. Animal studies
have shown that these thermal changes do not increase after six months,
and any char is absorbed and the interface becomes smooth over time
17
. As far as we know, there are no long-term clinical studies in
humans on the results of meniscal repair with use of the laser.
It has been reported that <2 mm of heat penetration occurs
in human meniscal tissue with either the monopolar or the bipolar
radiofrequency device
17
. The geometry of the tip of the radiofrequency device appears to
have a strong influence on thermal changes in the meniscus, but
we know of no animal or human clinical studies on the effect of
the tip. Studies in which radiofrequency was compared with different
laser wavelengths have demonstrated similar thermal changes in the meniscus
21
.
Chondroplasty
The treatment of articular cartilage with thermal devices is
controversial, as no evidence has established whether thermal smoothing
of rough articular cartilage has lasting beneficial effects.
Pulsing lasers have been shown to smooth down articular cartilage
and taper rough surfaces to a smooth interface. However, avascular
necrosis that was presumed to be due to the heat and/or the pulsing
effect of laser energy has been reported
22
. In vitro studies have demonstrated smoothing of articular cartilage
with penetration to subchondral bone under controlled conditions
23
. The Er:YAG and excimer lasers appear to cause less thermal penetration than
other lasers and radiofrequency devices
24
. As far as we know, there have been no human clinical studies analyzing
any laser system.
In vitro studies of smoothing or chondroplasty of articular cartilage
with use of radiofrequency devices have demonstrated conflicting
results
25
. Animal studies have demonstrated deep penetration with both monopolar and
bipolar radiofrequency devices
25
. As far as we know, there have been no human clinical studies on
the use of radiofrequency devices to treat articular cartilage lesions.
Overall, the heat from any thermal device has not demonstrated any
upregulation or healing of articular cartilage.
Articular cartilage is very fastidious, and heat destroys the
cartilage cells. There is controversy with regard to the best method
for histological evaluation of cartilage. Most studies to date have used
hematoxylin and eosin staining, which has been demonstrated to be
less accurate than confocal microscopy. However, the testing protocol
for confocal microscopy is also controversial
26,27
.
As far as we know, there is no evidence that articular cartilage
regenerates after d�bridement with either laser or radiofrequency.
Avascular necrosis in the subchondral bone as a result of laser use
has been reported
22
. It has also been suggested that avascular necrosis occurs as a
result of the use of radiofrequency, but this has not been substantiated.
Ligament Shrinkage (Thermal Capsulorrhaphy)
Studies have shown that heat denatures collagen, causing it to
fall back from its stable extended helical structure to a shortened,
more random, contracted state
28-33
. Recent procedures with thermal energy have incorporated the use
of lasers to tighten the ligaments of the shoulder capsule, and
over time this has led to techniques that incorporate radiofrequency
energy to shorten the shoulder ligaments and capsule. Two studies
on the treatment of shoulders with the holmium laser had favorable clinical
results34,35, but the subjects had a mixture of shoulder disorders. Numerous
studies have been presented at national meetings, but we know of
no published studies documenting the efficacy of this procedure
with use of radiofrequency energy.
In vitro studies have demonstrated that lower level, nonablative
thermal energy shortens collagen28,29. In vivo animal studies and
in vitro studies of human and animal tissues, in which the mechanical
properties and the various material properties of thermally shortened
ligaments were analyzed, have shown that these tissues are initially strong
and then become weaker and stretch out after a few weeks36,37. Animal
studies have suggested that, over time, this tissue returns to nearly
normal material properties at about twelve weeks
38,39
.
Commonly, thermal capsulorraphy is done for the treatment of
shoulder instability although the exact indications, technique,
amount of delivered energy, specific tissue to which the energy
should be delivered, and postoperative therapy regimens have not
been established or controlled. Unfortunately, the studies performed
to date have not quantified or qualified these areas of clinical
concern, and several of them have had mixed clinical indications,
with patients who had multidirectional instability, unidirectional instability
or subluxation, and voluntary dislocation grouped together40-42. Some
patients with Bankart tears have been included in these study groups
as well. There have been many reports of complications and reoperations
with thermal shortening. Overall, reports on the clinical results
of thermal capsulorrhaphy with radiofrequency for the treatment
of shoulder instability have been anecdotal, with a higher percentage
of failures associated with the thermal procedure than with traditional open
stabilization procedures
40-42
.
Many problems with the delivery of thermal energy to the shoulder,
either with a laser or more commonly a radiofrequency device, have
been described in anecdotal reports
36-39
. These include stiffness of the shoulder with adhesive capsulitis
and absent or destroyed anterior capsular structures, which create
a difficult clinical situation for the surgeon. Although the exact etiology
of the destruction is not clearly understood, the delivered temperature and
energy levels are variable and excessive heat can certainly contribute to
destruction of the ligaments and capsule in the shoulder. The possible
damage to the axillary nerve as a result of laser and radiofrequency
energy applications in the inferior pouch has been a strong concern.
The capsule is very thin posteriorly and laterally, and the axillary
nerve lies in close proximity to the shoulder capsule. Transient
axillary nerve pain and paresthesias have been reported
43
.
Although thermal shortening of collagenous tissue has been used
primarily to correct shoulder instability, thermal energy has also
been used to tighten the medial retinacular areas of the knee in association
with a lateral release and to tighten the loose lateral ligaments
in the ankle, according to anecdotal reports
44,45
. The concept of tightening the anterior cruciate ligament with
use of thermal energy has been discussed in several presentations.
However, no scientific evidence has demonstrated the clinical efficacy
of thermal energy for tightening the anterior cruciate ligament,
and a case report has shown destruction of the anterior and posterior
cruciate ligaments soon after thermal shortening46. More work needs
to be done in this area.
Tissue-Welding and Meniscal Repair
The structural changes induced in collagen and other proteins
by nonablative thermal energy can produce tissue welds
47,48
. Numerous studies have demonstrated that collagen fibers lose their
periodicity during heating and then shorten and thicken and split
into small fibrillary substructures, which closely interdigitate
across tissue defects to produce a seal. Functional repairs of vascular structures,
nerves, biliary ducts, and other tissues have been achieved with thermal
welding49,50. It has been postulated that the unraveling of collagen fibers
during heating is followed by their re-entwining during cooling. Small
and relatively delicate structures, such as those noted above, require
the use of minimal thermal energy with limited local heating to
achieve the desired effect. Much denser tissues, such as tendon
or meniscus, resist thermal welding unless some means of diffusion
of heat into the tissue can be found. Vital dyes, such as indocyanine green,
placed on the tissue at the site of the weld permit the absorption
of laser light when the absorption capacity of the dye is matched
to a specific laser wavelength.
Studies with lasers, vital dyes, and fibrin solders matched to
a specific wavelength have suggested that meniscal repairs are possible
51,52
. In vivo and in vitro studies have demonstrated that, in the short
term, the strength of the meniscal weld should be sufficient for
normal function51, but this has not been examined in a clinical study,
as far as we know. The ability to diagnose a torn meniscus at arthroscopy,
to introduce an appropriate photochemical agent, and to activate
that agent with the appropriate light, thus obtaining a bond, is
an appealing concept. We are still in the early stages of this research.
Recent studies of new monomers have shown that they have the ability
to bond, but some of them have an apparent toxic effect
53-58
. Hydrogels, which can hold tissues together through a surface phenomenon,
might also prove to be valuable. These substances are hardened by
ultraviolet light. Other chemical substances will be explored and
undoubtedly will be associated with different wavelengths of light
53-58
.
The cost of lasers and radiofrequency devices will determine
to some degree whether they will gain wider acceptance in musculoskeletal
surgery. Laser units range in price from $30,000 to $150,000 with
an additional charge per procedure for the fiberoptic cable and the
handheld arthroscopic probe. Some companies have made the probes
reusable to reduce costs. Hospitals are required to provide a specially
trained nurse or technician while the laser is in operation. These
costs usually result in a charge of $150 to $200 per treatment, which
is added to the hospital's charge for a given procedure.
In contrast, radiofrequency generators are usually donated to
the hospital or surgery center, and the charge for the handheld
pieces is approximately $100 to $125 per case. Generally, the handheld
pieces are not reusable and are not able to be sterilized without
damaging them. In the last several years, radiofrequency has all
but eliminated the use of lasers in arthroscopy, and there are at least
six companies competing for this expanding radiofrequency market.
Laser and radiofrequency procedures, therefore, add to the cost
of surgery, but it is not clear whether these costs exceed those
related to mechanical devices, particularly those that are disposable.
Overall, it appears that, while laser use has declined in spine
surgery and arthroscopy, the use of radiofrequency techniques has
expanded. Percutaneous laser disc decompression has been marginalized,
probably for the same reasons that chemonucleolysis and automated
percutaneous lumbar discectomy are presently out of favor. The intradiscal
electrothermal procedure is currently ascendant, although laser-assisted
endoscopic techniques seem to offer promise.
The use of radiofrequency has increased dramatically, and it
is now established as an adjunctive surgical tool that is used primarily
for tissue ablation in the knee and shoulder. The future of capsular
ligament shrinkage in the shoulder, knee, and ankle is still in question,
as it needs to be evaluated in sound, prospective, and well-controlled
clinical studies. Photodynamic therapy with laser-light activation
has been used in patients with rheumatoid arthritis, and experiments
with thermal welding and meniscal repair are continuing. The use
of gene therapy and collagen matrix with growth factors may also
involve the use of lasers and other thermal energy devices. Overall, however,
these devices have had limited acceptance by the orthopaedic community,
and to some degree they appear to remain largely investigative.
Ascher NW, Holzer P, Sutter B.
Percutaneous nucleus pulposus denaturation (abstract 149). Read
at the Eighth Congress of the International Society of Lasers for
Surgery and Medicine; 1989 Nov 4-7; Taipei, Taiwan.
Choy DS,Ngeow J. Percutaneous laser disc decompression in spinal stenosis. J Clin Laser Med Surg,1998;16: 123-5.. 16123
1998
[PubMed]
Liebler WA. Percutaneous laser disc nucleotomy. Clin Orthop,1995;310: 58-66.. 31058
1995
[PubMed]
Black J, Rhodes A, Lane GJ, Uppal
GS, Sherk HH.
The chronic effects of anterior cervical and percutaneous lumbar
discectomy using the holium: YAG laser-an animal model. In I.
Spine.
Volume 7, Laser discectomy. Philadelphia: Hanley and Belfus; 1993.
p 31-5.
State of the Art Reviews.
Farrar MJ, Walker A,Cowling P. Possible salmonella osteomyelitis of spine following laser
disc decompression. Eur Spine J,1998;7: 509-11.. 7509
1998
[PubMed]
Turgut M, Onol B, Kilinic K,Tahta K.. Extensive damage to the end-plates as a complication of
laser discectomy. An experimental study using an animal model. Acta Neurochir (Wien),1997; 139: 404-9.. 139404
1997
[PubMed]
Epstein NE. Laser-assisted diskectomy performed by an internist resulting
in cauda equina syndrome. J Spinal Disord,1999;12: 77-9.. 1277
1999
[PubMed]
Yeung AT.
Evolving methodology in the treatment of discogenic back pain by
selective endoscopic discectomy. Read at the Annual Meeting of the
International Intradiscal Therapy Society. 2001 May 24; Phoenix,
Arizona.
Casper GD, Hartman VL,Mullins LL. Results of a clinical trial of the holmium:YAG laser in
disc decompression utilizing a side-firing fiber: a two-year follow-up. Lasers Surg Med,1996;19: 90-6.. 1990
1996
[PubMed]
Knight MT, Vajda A, Jakab GV,Awan S. Endoscopic laser foraminoplasty on the lumbar spine-early
experience. Minim Invasive Neurosurg,1998;41: 5-9.. 415
1998
[PubMed]
Siebert W.
Percutaneous disc decompression. In:
Spine. State of the Art Reviews.
Volume 7, Laser discectomy. Philadelphia: Hanley and Belfus; 1993.
p 103-33.
Saal JS,Saal JA. Management of chronic discogenic low back pain with a
thermal intradiscal catheter. A preliminary report. Spine,2000; 25: 382-8.. 25382
2000
[PubMed]
Saal JA,Saal JS. Intradiscal electrothermal treatment for chronic discogenic
low back pain: a prospective outcome study with minimum 1-year follow-up. Spine,2000;25: 2622-7.. 252622
2000
[PubMed]
Kleinstueck FS, Diederich CJ, Nau WH, Puttlitz CM, Smith JA, Bradford DS,Lotz JC. Acute biomechanical and histological effects of intradiscal
electrothermal therapy on human lumbar discs. Spine,2001;26: 2198-207.. 262198
2001
[PubMed]
Wetzel FT, Anderson G, Lee C, Rashbaum
R, Peloza J, Phillips F.
Intradiskal electrothermal anuloplasty (IDET) to treat discogenic
low back pain: preliminary results of a multi center prospective
trial. Presented at the Annual Meeting of the International Society
for the Study of the Lumbar Spine; 2000 Apr 9-13; Adelaide, Australia.
Karasek M,Bogduk N. Twelve-month follow-up of a controlled trial of intradiscal
thermal anuloplasty for back pain due to internal disc disruption. Spine,2000;25: 2601-7.. 252601
2000
[PubMed]
Schaffer JL, Dark M, Itzkan I, Albagli D, Perelman L, von Rosenberg C,Feld MS. Mechanisms of meniscal tissue ablation by short pulse
laser irradiation. Clin Orthop,1995;310: 30-6.. 31030
1995
[PubMed]
Vangsness CT Jr, Ghaderi B, Brustein M, Saadat V,Carter J. Ablation rates of human meniscal tissue with the Ho:YAG
laser: the effects of varying fluences. Arthroscopy,1997;13: 148-50.. 13148
1997
[PubMed]
Vangsness CT Jr, Huang J,Smith CF. A spectrophotometer analysis of light absorption in the
human meniscus. Clin Orthop,1995;310: 27-9.. 31027
1995
[PubMed]
Vangsness CT Jr, Watson T, Saadatmanesh V,Moran K. Pulsed Ho:YAG laser meniscectomy: effect of pulsewidth
on tissue penetration rate and lateral thermal damage. Lasers Surg Med,1995;16: 61-5.. 1661
1995
[PubMed]
Vangsness CT Jr, Akl Y, Nelson SJ, Liaw LH, Smith CF,Marshall GJ. In vitro analysis of laser meniscectomy. Clin Orthop,1995;310: 21-6.. 31021
1995
[PubMed]
Garino JP, Lotke PA, Sapega AA, Reilly PJ,Esterhai JL Jr. Osteonecrosis of the knee following laser-assisted arthroscopic
surgery: a report of six cases. Arthroscopy,1995;11: 467-74.. 11467
1995
[PubMed]
Lane JG, Amiel ME, Monosov AZ,Amiel D. Matrix assessment of the articular cartilage surface after
chondroplasty with the holmium:YAG laser. Am J Sports Med,1997;25: 560-9.. 25560
1997
[PubMed]
Glossop ND, Jackson RW, Koort HJ, Reed SC,Randle JA. The excimer laser in orthopaedics. Clin Orthop,1995;310: 72-81.. 31072
1995
[PubMed]
Shellock FG,Shields CL Jr. Radiofrequency energy-induced heating of bovine articular
cartilage using a bipolar radiofrequency electrode. Am J Sports Med,2000;28: 720-4.. 28720
2000
[PubMed]
Trauner KB, Nishioka NS, Flotte T,Patel D. Acute and chronic response of articular cartilage to holmium:YAG
laser irradiation. Clin Orthop,1995;310: 52-7.. 31052
1995
[PubMed]
Mainil-Varlet P, Monin D, Weiler C, Grogan S, Schaffner T, Zuger B,Frenz M. Quantification of laser-induced cartilage injury by confocal
microscopy in an ex vivo model. J Bone Joint Surg Am,2001;83: 566-71.. 83566
2001
[PubMed]
Hayashi K, Markel MD, Thabit G 3rd, Bogdanske JJ,Thielke RJ. The effect of nonablative laser energy on joint capsular
properties. An in vitro mechanical study using a rabbit model. Am J Sports Med,1995;23: 482-7.. 23482
1995
[PubMed]
Hayashi K, Thabit G 3rd, Bogdanske JJ, Mascio LN,Markel MD. The effect of nonablative laser energy on the ultrastructure
of joint capsular collagen. Arthroscopy,1996;12: 474-81.. 12474
1996
[PubMed]
Hayashi K, Thabit G 3rd, Massa KL, Bogdanske JJ, Cooley AJ, Orwin JF,Markel MD. The effect of thermal heating on the length and histologic
properties of the glenohumeral joint capsule. Am J Sports Med,1997;25: 107-12.. 25107
1997
[PubMed]
Lopez MJ, Hayashi K, Fanton GS, Thabit G 3rd,Markel MD. The effect of radiofrequency energy on the ultrastructure
of joint capsular collagen. Arthroscopy,1998;14: 495-501.. 14495
1998
[PubMed]
Hecht P, Hayashi K, Cooley AJ, Lu Y, Fanton GS, Thabit G 3rd,Markel MD. The thermal effect of monopolar radiofrequency energy
on the properties of joint capsule. An in vivo histologic study
using a sheep model. Am J Sports Med,1998;26: 808-14.. 26808
1998
[PubMed]
Obrzut SL, Hecht P, Hayashi K, Fanton GS, Thabit G 3rd,Markel MD. The effect of radiofrequency energy on the length and
temperature properties of the glenohumeral joint capsule. Arthroscopy,1998;14: 395-400.. 14395
1998
[PubMed]
Hayashi K, Massa KL, Thabit G 3rd, Fanton GS, Dillingham MF, Gilchrist KW,Markel MD. Histologic evaluation of the glenohumeral joint capsule
after the laser-assisted capsular shift procedure for glenohumeral
instability. Am J Sports Med,1999;27: 162-7.. 27162
1999
[PubMed]
Hardy D, Thabit G 3rd, Fanton GS, Blin JL, Lortat-Jacob A,Benoit J. [Arthroscopic management of recurrent anterior shoulder
dislocation by combining a labrum suture with antero-inferior holmium:YAG
laser capsular shrinkage]. Orthop�de,1996;25: 91-3. German.. 2591
1996
Hecht P, Hayashi K, Lu Y, Fanton GS, Thabit G 3rd, Vanderby R Jr,Markel MD. Monopolar radiofrequency energy effects on joint capsular
tissue: potential treatment for joint instability. An in vivo mechanical,
morphological, and biochemical study using an ovine model. Am J Sports Med,1999;27: 761-71.. 27761
1999
[PubMed]
Schulz MM, Lee TQ, Sandusky MD, Tibone JE,McMahon PJ. The healing effects on the biomechanical properties of
joint capsular tissue treated with Ho:YAG laser: An in vivo rabbit
study. Arthroscopy,2001;17: 342-7.. 17342
2001
[PubMed]
Lu Y, Hayashi K, Edwards RB 3rd, Fanton GS, Thabit G 3rd,Markel MD. The effects of monopolar radiofrequency treatment pattern
on joint capsular healing. In vitro and in vivo studies using an
ovine model. Am J Sports Med,2000;28: 711-9. . 28711
2000
[PubMed]
Hayashi K, Hecht P, Thabit G 3rd, Peters DM, Vanderby R Jr, Cooley AJ, Fanton GS, Orwin JF,Markel MD. The biologic response to laser thermal modification in
an in vivo sheep model. Clin Orthop,2000;373: 265-76.. 373265
2000
[PubMed]
Schaefer SL, Ciarelli MJ, Arnoczky SP,Ross HE. Tissue shrinkage with the holmium:yttrium aluminum garnet
laser. A postoperative assessment of tissue length, stiffness, and
structure. Am J Sports Med,1997;25: 841-8.. 25841
1997
[PubMed]
Tibone JE, McMahon PJ, Shrader TA, Sandusky MD,Lee TQ. Glenohumeral joint translation after arthroscopic nonablative,
thermal capsuloplasty with a laser. Am J Sports Med,1998;26: 495-8.. 26495
1998
[PubMed]
Markel MD, Hayashi K, Thabit G 3rd,Thielke RJ. Changes in articular capsular tissue using holmium:YAG
laser at non-ablative energy densities. Potential application in
non-ablative stabilization procedures. Orthop�de,1996;25: 27-41. German.2527
1996
Gryler EC, Greis PE, Burks RT,West J. Axillary nerve temperatures during radiofrequency capsulorrhaphy
of the shoulder. Arthroscopy,2001; 17: 567-72.. 17567
2001
[PubMed]
Pluhar GE, Thabit G 3rd, Klohnen A, Vanderby R Jr,Markel MD. In vitro effects of holmium. YAG laser on caprine stifle
retinacular restraints. Clin Orthop,1998;356: 239-47.. 356239
1998
[PubMed]
Shapiro GS, Fanton GS, Dillingham MF,Perkash R. Lateral retinacular release. The holmium:YAG laser versus
electrocautery. Clin Orthop,1995; 310: 42-7.. 31042
1995
[PubMed]
Perry JJ,Higgins LD. Anterior and posterior cruciate ligament rupture after
thermal treatment. Arthroscopy,2000;16: 732-6.. 16732
2000
[PubMed]
Bass LS, Moazami N, Pocsidio J, Oz MC, LoGerfo P,Treat MR. Changes in type I collagen following laser welding. Lasers Surg Med,1992;12: 500-5.. 12500
1992
[PubMed]
Tang J, Godlewski G, Rouy S,Delacretaz G. Morphologic changes in collagen fibers after 830nm diode
laser welding. Lasers Surg Med,1997;21: 438-43.. 21438
1997
[PubMed]
Guthrie CR, Murray LW, Kopchok GE, Rosenbaum D,White RA. Biomechanical mechanisms of laser vascular tissue fusion. J Invest Surg,1991;4: 3-12.. 43
1991
[PubMed]
Oz MC, Bass LS, Popp HW, Chuck RS, Johnson JP, Trokel SL,Treat MR. In vitro comparison of thulium-holmium-chromium:YAG and
argon ion lasers for welding of biliary tissue. Lasers Surg Med,1989;9: 248-53.. 9248
1989
[PubMed]
Forman SK, Oz MC, Lontz JF, Treat MR, Forman TA,Kiernan HA. Laser-assisted fibrin clot soldering of human menisci. Clin Orthop,1995;310: 37-41.. 31037
1995
[PubMed]
Lauto A. Repair strength dependence on solder protein concentration:
a study in laser tissue-welding. Lasers Surg Med,1998;22: 120-5. . 22120
1998
[PubMed]
Judy MM, Nosir H, Jackson RW, Matthews
JL, Lewis DE, Utecht RE, Yuan D.
Bonding of human meniscal and articular cartilage with photoactive
1,8-naphthalimide dyes. In: Anderson R, editor.
Lasers in surgery: advanced characterization, therapeutics,
and systems VI. Proc. SPIE.
1996;2671:251-5.
Judy MM, Chen L, Fuh L, Nosir H, Jackson
RW, Matthews JL, Lewis DE, Utecht RE, Yuan D.
Photochemical cross-linking of type I collagen with hydrophobic
and hydrophilic 1,8-naphthalimide dyes. In: Jacques SL, editor.
Laser-tissue interaction VII.
Proc SPIE. 1996;2681:53-5.
Judy MM, Jackson RW, Nosir HR, Matthews
JL, Lewis DE, Utecht RE, Yuan D.
Repair of articular cartilage and meniscal tears by photoactive
dyes: in-vivo study. In: Laffitte F, Hibst R, Reidenbach H-D, Geschwind
HJ, Maira G, Pini R, Chiesa F, Krasner N, editors.
Laser applications in medicine and dentistry. Proc SPIE.
1996;2922:436-40.
Jackson RW, Nosir HR, Judy MM,Matthews JL. Repair of articular cartilage and meniscal tears by photoactive
dyes. Arthroscopy,1997;13: 392-3. . 13392
1997
Judy MM, Jackson RW, Matthews JL,Nosir HR. Healing results in meniscus and articular cartilage photochemically
welded with 1,8 naphthalimide dyes: 2 year results. Lasers Surg Med Suppl,1998;10: 237-50. . 10237
1998
Judy MM, Nosir HR, Jackson RW, Matthews
JL, Utecht RE, Lewis DE, Yuan D. Photochemical bonding of skin with
1,8-naphthalimide dyes. In: Delacretaz GP, Godlewski G. Pini R,
Steiner RW, Svaasand LO, editors. Laser-tissue interaction, tissue
optics, and laser welding III. Proc SPIE. 1998;3195:21-4.