TREATMENT
Immobilization Versus Mobilization
of Contused Muscle
a. Brief immobilization (less than 5 days) leads to
faster healing without further tissue damage while
prolonged immobilization results in muscle atro-
phy and delayed muscle activity in a rat model
(Jarvinen, 1975; Lehto, Duance, and Restall,
1985). In addition, early mobilization results in
increased tensile stiffness of contused muscle and
more rapid resolution of the contusion injury
(Jarvinen, 1976).
b.Clinical studies from the U. S. Military Academy
demonstrate that a brief period of immobilization
(24–48 h) with the involved muscle in a lengthened
position followed by mobilization results in earlier
recovery than prolonged muscle immobilization
(Jackson and Feagin, 1973; Ryan et al, 1991).
PHARMACOLOGIC TREATMENT
- Animal studies have demonstrated that both corticos-
teroids and nonsteroidal anti-inflammatory drugs
cause a decrease in the early inflammatory response
(Beiner et al, 1999); however, there is delayed muscle
regeneration and a decrease in the later tensile proper-
ties of the healed muscle. Recent animal studies also
show that anabolic steroids and growth factors can
produce a beneficial effect in the healing of contused
muscle (Beiner and Jokl, 2001). The clinical use of
these substances has not been approved, however. - Myositis ossificans is a concerning complication of
muscle contusion injury. The etiology of this abnor-
mal bone formation is unclear but is related to the
degree of muscle injury, the region injured (quadri-
ceps and brachialis), and the number of times the
muscle is subjected to trauma (Beiner and Jokl, 2001).
Clinically there is usually tenderness, swelling, loss of
motion, persistent warmth, and a firm mass in the area
of the bone formation. The abnormal bone is radi-
ographically evident by 4 weeks and resembles
mature bone by 6 months (Best, 1997). The bone fre-
quently resolves spontaneously. Surgical resection, if
necessary, should be delayed until the osteoblastic
activity has ceased (6 months to 1 year).
MUSCLE CRAMPS
- Muscle cramps commonly affect both athletes and
nonathletes. The gastrocnemius muscle and ham-
strings are most commonly involved but cramping can
involve nearly any muscle group. Cramps begin with
the muscle in a shortened position.- The cramp begins as a fasciculation from a single
focus within the muscle and then spreads throughout
the muscle. Electric evidence suggests that the source
of the abnormal activity is coming from the nerve
within the muscle (Best, 1997). - The etiology of muscle cramping is unclear but dehy-
dration and hyponatremia are frequently present.
Hypokalemia and hypocalcemia have also been impli-
cated (Best, 1997).
•Treatment includes passive stretching of the muscle
along with fluid and sodium replacement. - Athletes with repeated episodes of cramping should
undergo evaluation for electrolyte or endocrine disor-
ders.
TENDON INJURY AND REPAIR•Tendon injuries are secondary to direct trauma (lacer-
ations) or tensile overload.
•Tensile overload injuries are very common athletic
injuries and can occur acutely or as a result of chronic
overload.- Acute tendon overload usually results in injury to the
musculotendinous junction or a bony avulsion since
tendons can withstand high tensile loads. Rarely does
a normal tendon rupture midsubstance. - Chronic tendon overload injuries are common overuse
injuries and will be the focus of this section.
ANATOMY AND PHYSIOLOGY•Tendons consist primarily of type I collagen fibrils, a
proteoglycan matrix, and relatively few fibroblasts.
a. Type I collagen consists of two alpha-I polypeptide
chains and one alpha-2 chain. These three chains
are organized into a triple helix stabilized by
hydrogen and covalent bonds (Wood et al, 2000).
b. The collagen triple helix molecules are aligned in
a quarter-staggered arrangement to make up the
collagen microfibril. This results in alignment of
oppositely charged amino acids and contributes to
the tendon’s strength.
a. The microfibrils are then arranged in a parallel, well
ordered, and densely packed fashion. This organiza-
tion also contributes to the tendon’s tensile strength.
The microfibrils are combined with a proteoglycan
and water matrix to form collagen fascicles. The
tendon consists of groupings of these fascicles sur-
rounded by connective tissue that contains blood
vessels, nerves, and lymphatics (Wood et al, 2000).58 SECTION 1 • GENERAL CONSIDERATIONS IN SPORTS MEDICINE