prolotherapy and growth factor research

[Guest guest]

Sweet Relief from Biomechanics September 2004

By: K. Dean Reeves, MD

Cell proliferation is defined as the growth of new or similar cells.

Growth of cells, in turn, requires the presence of complex proteins

called growth factors. Prolotherapy is defined as " the injection of

growth factors or growth factor production stimulants to produce normal

cells or tissue. " 1 Injection of growth factors is performed by the vast

majority of physicians and in all general hospitals. The primary example

of this is the injection of the growth factor erythropoietin to help

patients with anemia to produce more normal red blood cells.2

Unlike red blood cell growth factors, many growth factors affect a

variety of cells, such as a liver growth factor that also causes brain

cells to multiply.3 But cells that are close by and similar, even cells

of different ligaments in the knee, respond differently to growth

factors.4 Therefore, in researching the effects of growth factors, we

need to remember that even similar structures can be unique in how they

repair (which growth factors they need). In addition, it will be

important to try a variety of growth factors in research, regardless of

whether their " name " suggests they will be applicable.

Growth factor research is under way in many areas such as injecting

growth factors in those with inadequate heart, brain or leg circulation

to grow new blood vessels.5-7 However, of particular interest from a

biomechanical perspective is the use of prolotherapy for the treatment

of sprains, strains, and arthritis.

What is a sprain/strain?

In a sprain the damage is to a ligament, which connects one bone to

another bone. In a strain the damage is to a tendon, a similar type of

structure but one that connects muscle to bone. A commonly held

misconception is that, with enough time, sprains and strains usually

heal completely. It has been reported that the best result one can hope

for after postinjury healing of connective tissue is only 50% to 70% of

preinjury tensile strength.8 Sprains and strains are best thought of as

damage to structures (ligaments/tendons) that have characteristics of

both a rope, which can be torn partially or completely, and putty, which

can be stretched but does not necessarily return to its former length.

Thus, sprains or strains often leave the sprained ligament or strained

tendon both weak and stretched out.

Biomechanical effects of sprain/strain

A weak and stretched-out ligament or tendon can also stretch the pain

nerve fibers that run through it. This type of malfunction in the pain

mechanoreceptors of connective tissue can persist as long as the

ligament or tendon remains stressed.9 Pathology experts have emphasized

for nearly two decades that the changes in chronic sprains and strains

are degenerative (an " osis " ), not inflammatory (an " itis " ), in nature.10

This is supported by reports of poor results using steroid injection to

treat chronic sprains/strains, which suggest that the pain is coming not

from inflammation11 but rather when pain nerves are stimulated in weak

or loose tissue.

Ligaments and tendons, when abnormal, can also cause referred pain and

referred numbness.12 Referred pain from ligaments and tendons can easily

be misinterpreted as a disorder of the spinal nerves (radiculopathy).

Although referred numbness is very common, the biomechanics of this is

not clearly understood.

A metaphor for a failing ligament or tendon is a cartoon character

dangling from a rope, with one fiber at a time giving way. When this

happens, the part of the muscle connected with that " rope " fiber

tightens reflexively, creating a taut band within the muscle. Reflex

contractions, also called twitch contractions, occur by reflex in the

muscle if the affected ligament or tendon is strummed like a guitar

string.9 Reflexively taut bands and twitch contractions in muscles are

characteristics of myofascial pain. This helps explain why methods of

treating myofascial pain that address only muscle changes often lead to

recurrent symptoms, since the ligament or tendon changes are not

repaired.

In addition, ligaments are responsible for holding disks and bony spinal

structures in position. When ligaments in the spine are abnormal or

loose, this may cause " segmental dysfunction. " Practitioners who use

manipulation to help restore back alignment are treating segmental

dysfunction. The need for frequent realignment may suggest that

looseness in a ligament or tendon is causing the segmental dysfunction.

The correlation between loose ligaments and arthritis was recognized

when knee arthritis developed in humans who had had knee cartilage

removed, particularly the medial meniscus. It is interesting to note

that to create arthritis in a dog one need only sever the anterior

cruciate ligament and three weeks later early changes of arthritis are

already seen.13 Bone spurs are frequently a reaction of the body to

compensate for a loose structure, with the spurs often growing in

directions parallel to those of the inadequate ligament/tendon fibers.

Typical x-ray findings for arthritis include bone spurs and loss of

cartilage. Both are found in joints that are deprived of normal ligament

support.

Chronic sprain/strain in the back is suspected of leading to reduced

intervertebral disk support, excessive disk movement, and excessive

pressure on the disk edges. This excess of disk pressure may be an

important contributor to degenerative disk disease and disk herniation.

Chronic sprains and strains result in weak or loose structures that

permanently stimulate pain fibers and cause myofascial pain and

segmental dysfunction. This pathology predisposes a patient to arthritis

and degenerative disk disease. It is clear that pain management

approaches that do not correct the original sprain and strain will be

limited in benefit.

Stages of healing and types of prolotherapy

After an acute injury, tendons and ligaments go through three stages of

healing: inflammatory, proliferative, and remodeling.10 These stages are

a response to the amount of cell damage that has occurred. In chronic

injury states or with microtrauma there is not enough new damage to

cells for the body to stimulate its own repair. Thus wear and tear

gradually accumulate without any repair until decompensation occurs. To

begin proliferation, a practitioner may inject growth factors directly,

inject a solution that produces growth factors without inflammation, or

inject a solution that produces growth factors by starting a temporary

inflammatory process that leads to growth (the way the body normally

heals).

Injection of growth factors

To skip the inflammatory phase and begin proliferation, primary growth

factors, either singly or in various combinations, may be used for

injection. Blood is a source of already produced common growth factors

such as insulin-like growth factor 1 (IGF-1), platelet-derived growth

factor (PDGF), and transforming growth factor (TGF). et al

demonstrated that even normal ligaments can grow stronger with exposure

to injected blood. A single injection of 0.15 ml of blood into the

patellar tendon of rabbits resulted in a significantly stronger tendon

(p < 0.014) with microscopic examination showing completely normal

cells.14 Injection of the patient's own blood has been studied for

treatment of tennis elbow in humans by et al. In that study,

average pain levels improved from 7.8 to 2.3 on a 10-point visual analog

scale after just one injection of the patients' own blood. Also, 23 of

28 patients with chronic symptoms not responsive to all usual treatments

had no pain with vigorous activity after one to three injections.15

Single or multiple growth factors can also be produced en masse in the

laboratory by genetic means and then injected. Forslund demonstrated the

potential of a single injection of a growth factor on ligament/tendon

tissue when he injected chondrocyte-derived morphogenetic protein-1

(CDMP-1) into rats' Achilles-equivalent tendon within hours of injury.

By eight days postinjection, CDMP-1 injected tendons were 39% stronger

than noninjected tendons. (P < 0.0002).16 Direct injection of growth

factors in human ligaments have not been reported to this point but

studies are under way.

Thus far, cartilage repair through the use of growth factor injection

has been reported only in animals. Young (maturing) rats developed a

thicker knee cartilage when injected just once during knee development

with bFGF (basic fibroblast growth factor).17 Also, full thickness holes

(3 to 4 mm) in rabbit knee cartilage have been shown to heal after

injection of HGF (hepatocyte growth factor).18

Injection without inflammation

Dextrose in concentrations greater than 10% causes a reliable temporary

inflammatory process, as evidenced by the need to put IV lines into

bigger veins for hospital patients receiving concentrated dextrose.

However, if dextrose concentration is kept at 10% or less, the osmotic

pressure on surrounding cells does not exceed the cells' ability to

compensate and inflammation does not occur.

A normal human cell contains only 0.1% dextrose. Upon culturing human

cells in glucose concentrations, it has been found that an environment

with as little as 0.6% glucose causes virtually all the main growth

factors for cartilage, ligament, and tendon-not bone-to elevate within

minutes to hours.19,20 In addition to elevating growth factors for

cartilage, some research indicates that elevating dextrose concentration

in a joint reduces cartilage-damaging protein (collagenase) levels.21

Why not just take dextrose orally? The stomach is designed to handle

high dextrose loads without such growth reactions. Sustained high

dextrose loads are not delivered to tissues except in patients with

diabetes, for whom control of blood sugar is altered. It has been

recognized that patients with diabetes develop extra blood vessels in

their eyes, and extra cells in their kidneys and blood vessels. To

bypass the stomach and place the dextrose in high concentration where it

is therapeutically needed, injection is required.

Two double-blinded placebo-controlled clinical trials of 10% dextrose

injection in arthritic joints have been conducted and involved both

large and small human joints. One such study demonstrated that in 111

arthritic knees with a pretreatment average of only 2 mm of residual

cartilage (35 knees had no residual cartilage in the medial

compartment), small-needle injection of only 9 ml of 10% dextrose at

zero, two, and four months led to improvements in pain and function

significantly better than those achieved in the control group.19

Improvements in walking pain, swelling, and buckling are shown in Figure

1. In addition, range of motion in the dextrose-treated knees improved

by 13.2 degrees . A second double-blinded study involved injecting

moderate to severely arthritic fingers (150 joints in 27 patients). With

injection of 0.5 ml of 10% dextrose in each joint at zero, two, and four

months, subjects injected with dextrose demonstrated significantly

better grip pain (p = 0.027) and flexion range of motion (p = 0.003)

than control patients injected with the same bacteriostatic water/dilute

lidocaine solution without dextrose (Figure 2).20

Injection of a solution that produces inflammation

The use of nonsteroidal anti-inflammatory drugs has been popular for

decades. However, the potential folly of preventing natural inflammation

after injury was pointed out by Elder, who demonstrated that

administering anti-inflammatory medication after an acute injury to the

medial collateral ligament of the knee in rats led to a 32% weaker

ligament after healing.22 In contrast, nearly 20 years earlier, Liu in

1983 confirmed the ability of an inflammatory solution (sodium

morrhuate) to thicken and strengthen normal medial collateral ligament

in the rat and measured a 47% increase in medial collateral ligament

mass after inflammatory solution injection.23

Chronic inflammation interferes with healing, but temporary inflammation

facilitates healing. Injecting relatively high (greater than 10%)

concentrations of dextrose, or any of a variety of other solutions such

as dilute phenol, causes temporary inflammation. Nearly 50 years ago

Hackett demonstrated that temporary inflammation not only thickens

ligaments and tendons, but it also creates a bigger connection to

bone.12 Hackett used an inflammatory solution called Sylnasol, which is

not currently available.

Four double-blinded studies have been conducted to investigate

inflammatory injection in chronic low back and leg pain (Figure 3).

Unfortunately, the low back has a complicated ligament/tendon structure

and proportionally complex referral patterns. These four studies were

well blinded, but did not have a true placebo control, since needling

itself would be expected to result in microbleeding with release of

natural growth factors from blood. Nevertheless, the two researchers who

used complete injection for ligaments responsible for both back and leg

pain found that including the inflammatory proliferant (phenol 1.25%,

dextrose 12.5%, glycerine 12.5%) was significantly (p < 0.00124) or

nearly significantly ( p = 0.05625) better than needling alone. In each

study, six- to 12-month follow-up revealed an impressive 60% sustained

reduction in pain and a comparable reduction in disability ratings.

Yelland26 published a study showing sustainable benefit in both dextrose

and control (saline) groups consistent with a therapeutic benefit from

needling alone. However, his study was hampered by an incomplete

injection method that did not introduce proliferant in key areas such as

facet ligaments, multifidi, or, for the first four treatments, the deep

SI ligament. Dechow27 published strikingly different results, which in

retrospect was largely because patients were selected by a

rheumatologist who excluded patients with leg pain. Patients were then

injected by a different physician who was instructed to inject only

certain areas without being allowed to examine the patients. These areas

were those that would refer leg pain, not primarily back pain; the

treating physician used leg-pain specific injection for patients without

leg pain.

These low back pain studies therefore suggest that it is critical for

the injecting physician to examine the patient, be familiar with

referral patterns for ligaments and tendons, and to inject all sources

of pain. It will also be important to consider that degenerative disks

can themselves be sources of low back and leg pain. Indeed, Klein et

al25 reported on lumbar intervertebral disk injection with an

inflammatory solution (glucosamine + chondroitin sulfate + dextrose +

dimethyl sulfoxide) in patients whose pain was reproduced by disk

injection (discogram). They found that 57% of patients improved markedly

after disk injection, achieving 72% improvement in disability scores and

76% in pain scores. A positive discogram did not perfectly predict who

would and would not respond, and further research is indicated. A study

on simple dextrose injection for pain from disk origin is nearing

completion at this time.

For sprain and strain to heal, tendons or ligaments need to both thicken

and tighten, since they are both thinned and stretched when injured. To

demonstrate the ability of simple dextrose injection to tighten loose

ligament, a study was conducted on 16 consecutive patients with laxity

of the ACL ligament as measured by a KT-1000 arthrometer.28 Ten percent

to 25% dextrose was used in this study, depending on patient tolerance.

Injection of 6 to 9 ml of dextrose solution (depending on comfort level

with injection) using an inferomedial approach was performed every two

months for a year, and then on an as-needed basis for knee pain.

Fourteen out of 16 patients had moderate to severe knee osteoarthritis

at study onset in addition to measured ACL laxity. At three years post

study commencement, patients on average experienced a 44% improvement in

pain, a 64% improvement in swelling, and a 72% improvement in looseness

(KT1000 side-to-side difference) (Figure 4). Rather than losing range of

motion over time, these patients experienced an average improvement in

flexion range of motion of 10.5 degrees . For a condition typically

associated with declining function, (either moderate to severe

osteoarthritis or ACL laxity), these results are encouraging.

The future of prolotherapy

Applications for prolotherapy are as broad as the diagnosis of " osis " or

degenerative change in either connective tissue or cartilage. Common

conditions that have responded quite successfully to prolotherapy

empirically and merit further study include: temporomandibular joint

disorder, shoulder laxity, bicepital tendinosis, medial and lateral

epicondylosis, sprained wrist (pseudo-DeQuervain's), osteoarthritis of

the knee and finger, gluteal and trochanteric tendinosis, distal

hamstring tendinosis, knee laxity, Achilles tendinosis, chronic ankle

sprain, plantar fasciosis, metatarsalgia, costochondrosis, osteitis

pubis, thigh adductor strain, and pelvic floor sprain/strain. Chronic

neck and upper and lower back pain respond as well but are much more

difficult to study with consistency between investigators.

Another way to obtain objective and reproducible evidence of healing

ligament and tendon is via new-generation ultrasound. These machines

provide a detailed view of connective tissue and show defects associated

with tendinosis and ligamentosis.

The future of prolotherapy in treating athletes is expected to be in the

use of non-inflammatory solutions during the sports season to enhance

speed and degree of repair from injuries, and as-needed treatment of

injuries off-season with stronger solutions for further repair. The

chronic pain that so many athletes expect to endure should be

substantially reduced with prolotherapy. A study of elite rugby players

that was just accepted for publication is representative of the

potential impact of proliferant injection in the athlete.29 The subjects

of this consecutive-patient study were primarily members of the rio,

Argentina, rugby team. This is the premiere city team in Argentina and

supplies athletes for the Argentinian national rugby team. All subjects

had groin and abdominal muscle strain for an average of 15 months that

was unresponsive to all usual therapeutic approaches. None of these

athletes could play at high level and all had pain even with self-care.

After an average of 2.8 sessions of dextrose injection into thigh and

abdominal muscle attachments, 20 of the 24 athletes were completely

pain-free and 22 had returned to unrestricted high-level play.

K. Dean Reeves, MD, is a clinical associate professor of physical

medicine and rehabilitation at the University of Kansas Medical Center.

References are available at www.biomech.com.

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