C h a p t e r 4 3
Disorders of the Skeletal System: Trauma, Infections, Neoplasms, and Childhood Disorders
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Sports-Related Injuries
Sports and athletic activities are particularly common
causes of acute and overuse injuries of the musculoskel-
etal system. Acute injuries are caused by sudden trauma
and include injuries to soft tissues (contusion, strains,
and sprains) and to bone (fractures).
Overuse injuries have been described as chronic inju-
ries, including tendinopathies, stress fractures, com-
partment syndrome, and shin splints, that result from
constant high levels of physiologic stress without suf-
ficient recovery time.
2–4
They commonly occur in the
elbow (“little league elbow” or “tennis elbow”) and
in tissue where tendons attach to the bone, such as the
heel, knee, hip, and shoulder.
Factors that increase the likelihood of sports injuries
include intrinsic and extrinsic risk factors.
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Intrinsic risk
factors are those that are unique to the individual that
increase the likelihood of sustaining an injury, such as
maturation status. Contact sports pose a greater threat
for injury to the neck, spine, and growth plates in chil-
dren and adolescents, who have not yet reached matu-
rity. Extrinsic risk factors are those that, when applied
to the athlete, may increase the risk of injury. They may
include training methods, or equipment, and environ-
ment that may have an effect on the magnitude, stress,
or force applied to the body. They include factors such as
athletic activity that is repeated so often that areas of the
body do not have enough time to heal between efforts.
Injuries can often be prevented by proper training, use
of safety equipment, and limiting the level of competi-
tion according to skill and size rather than chronologic
age. Adequate warm-up time, hydration, and proper
nutrition are also key factors in injury prevention.
SoftTissue Injuries
Most skeletal injuries are accompanied by soft tissue
(muscle, tendon, or ligament) injuries. These injuries
include contusions and hematomas.
A contusion is an injury, or
bruise,
that results from
direct trauma and is usually caused by striking a body
part against a hard object.
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Although the resulting dis-
ability is usually minor, some contusions can be quite
painful. Muscle bruises are common in all athletic
events, even the so-called noncontact sports. The thigh
and the arm are the most commonly involved. In contu-
sions, the skin overlying the injury remains intact while
the injured tissue undergoes a well-defined sequence of
events including microscopic rupture of blood vessels
and damage to muscle cells, swelling, and inflammation.
The area often becomes ecchymotic (i.e., black and blue)
because of local hemorrhage; later, the discoloration
gradually changes to brown and then to yellow as the
blood is reabsorbed.
A large area of local hemorrhage is called a
hema-
toma.
Hematomas cause pain as blood accumulates and
exerts pressure on nerve endings. The pain increases
with movement or when pressure is applied to the area.
The pain and swelling of a hematoma take longer to
subside than those accompanying a contusion.
The treatment for a contusion and a hematoma con-
sists of elevating the affected part and applying cold for
the first 24 hours to reduce the bleeding into the area. A
compression wrapping is sometimes helpful in the early
stages. Reinjury is avoided by appropriately protect-
ing the area and allowing for complete healing to occur
before returning to activities.
Joint (Musculotendinous) Injuries
Joints, or articulations, are sites where two or more
bones meet. Joints (i.e., diarthrodial) are supported by
tough bundles of collagenous fibers called
ligaments
that
attach to the joint capsule and hold the articular ends of
bones together and by
tendons
that join muscles to the
periosteum of the articulating bones (see Chapter 42).
Joint injuries usually involve mechanical overloading or
forcible twisting or stretching.
Strains and Sprains
Strains and sprains are both musculoskeletal injuries,
but they differ in terms of the tissue that is affected.
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Strains involve muscles, or more precisely the muscle–
tendon unit. Sprains involve the supporting ligaments
of a joint.
A
strain
is a stretching or partial tear in a muscle or
a muscle–tendon unit. Strains commonly result from
sudden stretch of a muscle that is actively contracting.
Although there usually is no external evidence of a spe-
cific injury, an inflammatory response develops at the
injured site, followed by fibrous tissue replacement of
the damaged muscle fibers. Muscle strains are usually
characterized by pain, stiffness, swelling, and local ten-
derness. Pain is increased with stretching of the muscle
group. Strains can occur at any age but are more com-
mon in middle-aged and older adults. With aging, the
collagen fibers in the muscle–tendon unit change; as a
result, muscles have decreased elasticity and are more
susceptible to injury. Common sites of muscle strains are
the lower back and the cervical region of the spine. The
elbow and the shoulder are also supported by muscle–
tendon units that are subject to strains. Strains of mus-
cle units around the hip, hamstring, and quadriceps are
commonly associated with athletic activities. Proper
warm-up exercises increase the flexibility of muscle–tendon units and help prevent these types of injuries.
A
sprain,
which involves the joint ligaments or cap-
sule surrounding the joint, resembles a strain, but the
pain and swelling subside more slowly. It usually is
caused by abnormal or excessive movement of a joint.
With a sprain, the ligaments may be incompletely torn
or, in a severe sprain, completely torn or ruptured
(Fig. 43-1). The signs of sprain are pain, rapid swell-
ing, discoloration, and limitation of function. Any joint
may be sprained, but the ankle joint is most commonly
involved, especially in high-risk sports such as basket-
ball. Most ankle sprains occur in the lateral ankle when
the foot is turned inward under a person, forcing the
ankle into inversion beyond its structural limits. Other
common sites of sprain are the knee (the collateral
