F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
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L4 SEGMENT
Hip flexion and adduction is quite powerful and the outwards rotation of the legs is more
marked as the presence of the obturator externus adds to the function of the iliopsoas in
this respect. Sartorius is strong enough to produce some flexion of the knee. Extension
of the leg is also increased due to greater power of the rectus femoris which is now
supported by the function of vastus lateralis and medialis. The patient is able to stand
and walk slowly on even ground by stabilizing the knees fairly well but is not able or
has greatest difficulty to walk upstairs. Moreover, as a result of the paralysis of the gluteus
medius the oscillation of the pelvis in the frontal plane is impeded during walking and
the gait is of wobbling type which is similar to the insufficiency of the abductors in
congenital dislocation of the hip. The knee jerks are absent.
Sensory function is present over the whole anterior aspect of the thighs, extending
distally to the upper medial aspect of the knees, otherwise there is complete sensory loss
in legs and saddle area.
L5 SEGMENT
Hip flexion and adduction is of full power and so is extension of the leg. The quadriceps
is of full strength and, as the main flexor of the knee, the biceps femoris is still paralysed
and the inner hamstrings are not strong enough to counteract the strong action of the
quadriceps, this results in hyperextension of the knee during walking and may lead,
without appropriate caliper preventing hyperextension, to a genu recurvatum. Although
the tensor fasciae latae and gluteus medius are functioning, their power is not strong
enough to prevent the wobbling gait, although this is less pronounced than in L4 lesions.
Below the knee the tibialis anterior and posterior are functioning, and, as the segmental
innervation of the former is almost entirely by L4, its action is very powerful resulting
in equino-varus position of the foot as its antagonists, the peroneal muscles, are still
paralysed. Knee jerks are elicitable.
Sensory function is present over the whole anterior aspect of the thighs and the medial
aspect of the legs, including inner ankle and innerside of the soles, while the dorsum of
the feet, outer aspect of the legs and ankles and posterior aspect of the lower limbs and
the saddle area are anaesthetic.
SI-S2 SEGMENTS
The Si syndrome is characterized through the position of the foot in dorsiflexion (pes
calcaneum), as a result of the paralysis of the triceps surae and flexors of the toes, and,
therefore, there is overaction of the extensor digitorum longus, extensor hallucis longus
and tibialis anterior. The foot is no longer in extreme supination as the peronei are of
good power. Flexion of the foot in pronation is possible by action of the peroneus longus
through its insertion on the first metatarsal. The function of semitendinosus and semi-
membranosus is increased but biceps femoris may still be paralysed or show only weak
function. The ankle jerks are absent and may be paradox (dorsiflexion of the foot);
plantar stimulation does not produce any response.
