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Hakkinen Arja, PhD
Kuukkanen Tiina, PhD
Tarvainen Ulla, PT
Ylinen Jari, MD ABSTRACT Disc prolapse and nerve compression
is a common source of low back pain, and 5-10% of these herniations do not
resolve and require surgical intervention. Most of these injuries occur with twisting motions (11.4% of
accidental back injuries, and 49% of nonaccidental back injuries), and
normal function of the back requires complex interactions between skeletal
muscle, motor control, circulation, metabolic capacity, and pain-free ROM.
The long period of reduced mobility and function prior to the
surgery can lead to disuse atrophy and impairment of the neural activation
rates. Different studies have
shown that in disc herniation patients, there is a loss of type II fibers
in the multifidus and surrounding connective tissue.
This loss of explosive power and function could result in loss of
stability during normal daily activities that require a rapid response.
It has also been shown that muscle retraction during surgery can
damage this function, and longer retraction times during surgery result in
decreased extensor muscle strength. After disc surgery, 22-45% of
patients experience residual sciatica, 30-70% have residual back pain.
Most do not regain their previous level of function, and 60% have
reduced lifting and strength capacities.
This study chose to measure back extensor and flexor strength,
endurance, and pain levels 2 months after disc surgery. A total of 30 subjects who had
surgery to different disc levels (most were L4-5 and L5-S1) were tested 2
months after surgery. The
protocol used after the surgery included avoidance of sitting in soft
chairs for 4 weeks, restrict lifting/carrying/forward bending for up to 6
weeks, performing light stretching and mobility, and return to light job
work at 6 weeks (2 months for jobs with heavier lifting).
The control subjects were age, sex, height and weight matched with
no history of back problems. Mean
pre-op back pain time was 17 months, and leg pain time was 17 months. Subjective pain values did reduce for the study group after
the surgery. Dynamometer back extensor and
flexor explosive isometric strength was determined in a seated position
with the hips and knees at 90 degrees.
Rotational strength was also assessed, as was flexor and extensor
endurance using either supine partial sit-ups or prone back extension
against gravity. Pain levels
on a 0-100mm scale were recorded for all subjects before and during the
testing. Healthy control subjects had 44%
greater isometric trunk flexion strength and 36% higher back extensor
strength during the tests, with no pain, while the study group did record
pain. Force-time curves were
also significantly reduced in the study group, and both the trunk flexion
and extension endurance rates were 70% reduced.
Rotational strength did not have a significant change until the
lower extremities were rotated in the same direction as the trunk was
turning, and then there were reductions in the strength capacity of the
control subjects. Other
studies have shown that as the lower extremities and lower trunk are
rotated in the opposite direction, that strength significantly diminishes. COMMENTS There is still no specific protocol
for post-discectomy patients, with some physicians telling the patients
nothing, others telling them to go do what ever they choose, and others
with more conservative approaches, like these authors used.
Often, when these patients come to PT on month after surgery to
condition or reduce pain, they don’t have a clue if they have any weight
restrictions or contraindicated activities.
It puts us in the precarious position of not knowing what to do, as
we don’t have a clue how extensive their tissue damage was, how bad the
herniation was, and often even if there was a partial laminectomy!
An error on our side that causes re-injury could be difficult to
get out of, especially since there are few studies that would support what
we are trying to perform. I
suggest working with your local spine surgeons to come up with a mutually
agreeable protocol for post-discectomy patients, focusing on flexibility,
conditioning, pelvic neuromuscular control, and eventually more aggressive
spine and hip strengthening. Working
with the surgeon to measure outcomes of these protocol patients and
comparing to those patients who did not undergo therapy would provide
valuable support for physical therapy.
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