AJR 2005; 184:1481-1485
© American Roentgen Ray Society
Skimboarder's Toe: Findings on High-Field MRI
Lane F. Donnelly1,
Jeffrey B. Betts and
Bradley L. Fricke
1 All authors: Department of Radiology, Cincinnati Children's Hospital Medical
Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039.
Received May 6, 2004;
accepted after revision August 26, 2004.
Address correspondence to L. F. Donnelly
(Lane.Donnelly{at}cchmc.org).
Abstract
OBJECTIVE. Our purpose is to report hyperdorsiflexion injuries of
the metatarsophalangeal joints associated with the sport of skimboarding and
to describe the MRI appearance of these injuries.
CONCLUSION. Skimboarding can be associated with hyperdorsiflexion
injuries of the metatarsophalangeal joint. MRI shows that such injuries are
associated with hyperdorsiflexion of the extensor hallucis longus or extensor
digitorum longus tendon, causing tear of the extensor expansion. Unlike turf
toe, in which the plantar plate is involved, skimboarder's toe involves
structures dorsal to the metatarsophalangeal joint.
Introduction
Skimboarding is a beachside sport. Skimboards have a similar appearance to
small surfboards, with the exception that there are no ventral fins. As
opposed to surfing, in which the surfer floats in the water on the surfboard
and then rides the wave toward the beach, the skimboarder stands on shore,
runs toward the water, drops the board to the ground, and jumps on it in very
shallow water (Fig. 1). The
skimboarder then hydroplanes toward deeper water and jumps the waves as they
approach inward. Skimboarding dates to the late 1920s, when lifeguards at
Laguna Beach created skimboards out of pieces of wood to move across the beach
[1]. Skimboarding became
gradually more popular in the 1960s and 1970s. In the 1980s, a skimboarder was
featured on the cover of Sports Illustrated
[1]. More recently, the
popularity of skimboarding has increased markedly. There are now tours for
professional skimboarders
[1–3],
magazines dedicated to the topic
[2], and multiple commercial
manufacturers of professional-grade skimboards
[3,
4]. Although most who partake
in skimboarding are children and teenagers, the sport is gaining popularity
with some adults.
The act of jumping on a moving skimboard, hydroplaning through several
millimeters of water, and potentially falling in the hard sand is associated
with a number of possible injuries. Although most of these injuries consist of
either skin abrasions or contusions, we here report similar injuries to the
region of the metatarsophalangeal joint in two adult skimboarders and describe
the imaging appearance on high-field MRI.
Subjects and Methods
Case 1
A 39-year-old male skimboarder received an acute injury to the region of
the left first metatarsophalangeal joint. After the skimboarder ran toward and
jumped onto the moving skimboard sideways with left foot forward, the
skimboard moved posteriorly in relationship to the skimboarder, resulting in
hyperdorsiflexion of the left foot, specifically the region of the first
metatarsophalangeal joint. The subject experienced immediate and severe pain.
Shortly after the injury, marked soft-tissue swelling and contusion became
apparent dorsal to the first metatarsophalangeal joint. For multiple weeks,
pain was persistent, particularly when the first metatarsophalangeal joint was
dorsiflexed. Because of persistent pain and the undetermined nature of the
injury on physical examination, MRI of the foot was performed (Fig.
2A,
2B,
2C). Images were obtained on a
3-T MRI scanner (Magnetron Trio, Siemens). Sequences included axial
(footprint) T1-weighted spin-echo images (TR/TE, 800/8.8; bandwidth, 370 Hz;
field of view, 140 mm; matrix, 256 x 320 pixels; number of excitations,
1; slice thickness, 3 mm; gap, 0.5 mm; time, 2 min 56 sec), axial (footprint)
and sagittal T2-weighted fast spin-echo images (3,000/61; bandwidth, 130 Hz;
field of view, 180 mm; matrix, 256 x 320 pixels; number of excitations,
2; slice thickness, 3 mm; gap, 0.5 mm; time, 4 min 12 sec), and coronal
(short-axis) intermediate-weight images (3,010/26; bandwidth, 130 Hz; field of
view, 70 x 140 mm; matrix, 128 x 320 pixels; number of
excitations, 2; slice thickness, 3 mm; gap, 0.6 mm; time, 2 min).
View larger version (109K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A. —39-year-old male skimboarder who sustained hyperdorsiflexion
injury of left first metatarsophalangeal joint. Sagittal T2-weighted image of
first metatarsophalangeal joint shows soft-tissue swelling
(arrowheads) predominantly dorsal to first metatarsophalangeal joint.
Dorsal aspect of extensor expansion is disrupted (large arrow).
Plantar plate is intact (small arrows).
|
|
View larger version (115K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B. —39-year-old male skimboarder who sustained hyperdorsiflexion
injury of left first metatarsophalangeal joint. Axial (footprint) T2-weighted
fast spin-echo image shows increased-signal-intensity edema surrounding first
and second metatarsophalangeal joints. Extensor expansion shows laxity and
disruption medially (arrows). Some edema is seen within first
metatarsophalangeal head (arrowhead).
|
|
View larger version (73K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C. —39-year-old male skimboarder who sustained hyperdorsiflexion
injury of left first metatarsophalangeal joint. Coronal (short-axis) fast
spin-echo intermediate-weight image shows a rind of high-signal-intensity
edema (arrows) surrounding distal metatarsal bone. Edema is more
prominent dorsally. Extensor expansion is not well visualized, secondary to
injury. Extensor hallucis longus tendon is intact (arrowhead).
|
|
Case 2
A 37-year-old male skimboarder received an acute injury similar to that
described in case 1. After the skimboarder ran toward and jumped onto the
moving skimboard, the board moved posteriorly, resulting in a
hyperdorsiflexion injury of the right foot in the region of the second
metatarsophalangeal joint. The subject experienced immediate, severe pain.
Dorsal soft-tissue swelling and marked contusion resulted from the injury. For
multiple weeks, pain persisted, particularly when the first
metatarsophalangeal joint was extended. Because the pain persisted for several
weeks and the nature of the injury was undetermined on physical examination,
MRI was performed, using the same protocol as for case 1.
Results
Case 1
MR images showed marked increased T2-weighted signal intensity within the
soft tissues dorsal to the first and second metatarsophalangeal joints,
consistent with posttraumatic edema (Fig.
2A,
2B,
2C). The largest component of
edema was dorsal to the first metatarsophalangeal joint. Increased T2-weighted
signal intensity was also seen within the bone marrow of the first
metatarsophalangeal head. No bone fracture was identified. The flexor hallucis
longus tendon was intact and appeared normal. However, complete disruption of
the dorsal and lateral aspects of the extensor expansions was seen (Fig.
2A,
2B,
2C). Minimal edema was seen
ventral to the metatarsophalangeal joints. The plantar plate of the first and
second metatarsophalangeal joints had the normal low signal intensity without
evidence of tear.
The subject was treated conservatively and poorly complied with rest. Nine
months after the initial injury, symptoms were markedly improved, with only
intermittent pain that occurred when the subject unintentionally dorsiflexed
the great toe during certain activities.
Case 2
MRI findings included increased T2-weighted signal intensity within the
soft tissue dorsal to the second metatarsophalangeal joint, consistent with
posttraumatic edema (Fig. 3A,
3B,
3C). Markedly increased
T2-weighted signal intensity was seen within the marrow of the second proximal
phalanx. A nondisplaced intraarticular avulsion fracture was present in the
medial aspect of the second proximal phalanx (Fig.
3A,
3B,
3C). Disruption and laxity were
identified within the medial aspect of the extension expansion of the second
metatarsophalangeal joint. The second extensor digitorum longus tendon was
intact (Fig. 3A,
3B,
3C). Minimal edema was present
ventral to the metatarsophalangeal joints. The plantar plate of the first and
second metatarsophalangeal joints had the normal low signal intensity without
evidence of tear.
View larger version (169K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A. —Hyperdorsiflexion injury of second metatarsophalangeal joint
of 37-year-old skimboarder. Axial (footprint) T2-weighted fast spin-echo image
shows increased signal intensity within soft tissues surrounding second
metatarsophalangeal joint, consistent with edema. High signal intensity is
seen within marrow of second proximal phalanx (arrows), consistent
with edema. Wavy and discontinuous medial aspect of extensor expansion
(arrowheads) is consistent with disruption.
|
|
View larger version (200K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B. —Hyperdorsiflexion injury of second metatarsophalangeal joint
of 37-year-old skimboarder. Axial (footprint) T1-weighted spin-echo image
shows low-signal-intensity, nondisplaced facture (arrow) through
medial aspect of proximal portion of first phalanx.
|
|
View larger version (104K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C. —Hyperdorsiflexion injury of second metatarsophalangeal joint
of 37-year-old skimboarder. Sagittal T2-weighted fast spin-echo image shows
predominance of high-signal-intensity edema (large arrows) in dorsal
soft tissue surrounding second metatarsophalangeal joint. Edema is scarce in
plantar region. Dorsal aspect of extensor expansion is disrupted and poorly
defined (small arrows). Signal intensity is increased in second
proximal phalanx, consistent with edema. Plantar plate (arrowheads)
has normal low signal intensity.
|
|
The subject was treated conservatively. Four months after the initial
injury, the subject remained symptomatic but symptoms had improved. The
subject still could not participate in some preinjury activities, such as
distance running, without significant pain.
Discussion
Most professional-grade skimboards are made of a hard outer shell
[3,
4]. Skimboarders typically
apply wax to the superior surface of the skimboard to decrease the likelihood
of the feet slipping when mounting the skimboard. When mounting a skimboard,
the skimboarder transitions from running frontward at full speed to landing on
the skimboard facing sideways with one foot forward
(Fig. 1). Use of the toes helps
the skimboarder's feet grip the board. During this process, if the board slips
posteriorly in relationship to the skimboarder, hyperdorsiflexion at the level
of the metatarsophalangeal joints may result (Fig.
4A,
4B). The presence of wax on the
landing surface of the skimboard, holding the foot in position, most likely
further increases the risk of this type of injury. We have shown this type of
injury in two skimboarders.
View larger version (16K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A. —Diagrams of structures in dorsal aspect of
metatarsophalangeal joint and mechanism of hyperdorsiflexion injury. With foot
in neutral position, extensor hallucis longus tendon (blue) traverses
under extensor expansion (white fibrous band) at level of
metatarsophalangeal joint (arrow).
|
|
View larger version (17K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B. —Diagrams of structures in dorsal aspect of
metatarsophalangeal joint and mechanism of hyperdorsiflexion injury. With foot
in hyperdorsiflexion, extensor hallucis longus tendon exerts force in dorsal
direction at level of metatarsophalangeal joint, leading to disruption of
dorsal portion of extensor expansion (arrow).
|
|
Anatomically, in the region of the first metatarsophalangeal joint, the
extensor hallucis longus tendon passes dorsal to the joint. In this region, a
band of circumferential fibrous tissue passes around the extensor hallucis
longus tendon and helps hold it in place
[5]. This band of fibrous
tissue is essentially a thickening of the dorsal aspect of the joint capsule
and has been referred to by various names, including the extensor expansion
[5] and the dorsal
metatarsophalangeal capsule
[6]. When the extensor hallucis
muscle contracts to extend or dorsiflex the great toe, the extensor expansion
acts as a pulley and holds the extensor hallucis longus tendon in place.
During trauma, if the first toe is acutely hyperdorsiflexed, forces apply to
the extensor hallucis longus tendon in the dorsal direction, potentially
resulting in tearing of the dorsal extensor expansion (Fig.
4A,
4B). The anatomy is similar in
the second through fifth toes; the extensor digitorum longus tendons pass
beneath the extensor expansions of each of those digits in the region of the
metatarsophalangeal joint. In case 1, the hyperdorsiflexion injury occurred in
the region of the first metatarsal joint, resulting in disruption of the
extensor expansion. In case 2, the hyperdorsiflexion injury was at the second
metatarsophalangeal joint and resulted in both a tear of the extensor
expansion and an avulsion fracture from the proximal portion of the phalanx.
In both cases, MRI showed marked soft-tissue edema in the surrounding soft
tissues, associated bone marrow edema, and wavy and discontinuous extensor
expansions consistent with disruption. The associated soft-tissue edema was
predominantly dorsal. A component of medial or lateral stress with the foot
dorsiflexed may also contribute to stress on the joint capsule and to the
potential for injury to the extensor expansions.
Another acute sports injury related to hyperdorsiflexion of the
metatarsophalangeal joint is commonly referred to as turf toe
[6–11].
Turf toe is most commonly described in football players and results from a
combination of the lightweight, flexible shoes worn by the players and the
hard, artificial surfaces on which they play. There have only been a few
reports of the MRI findings for turf toe
[6–9].
Depending on the source, turf toe has been described as occurring more
commonly in either the first or the second metatarsophalangeal joint, similar
to our observations for skimboarding injuries
[6–9].
However, the clinical symptoms and MRI appearance described for turf toe
are different from what was observed in the two skimboarders described here.
With turf toe, the symptoms and imaging findings involve predominantly the
structures at the plantar aspect of the metatarsophalangeal joint
[6–11].
In the description of turf toe, hyperdorsiflexion of the metatarsophalangeal
joint increases tension on the plantar aspect of the joint. Anatomically, at
the plantar aspect of the metatarsophalangeal joint is a "plantar
plate" that consists of fibrocartilaginous tissue
[6–9].
The plantar plate attaches to the proximal phalanx distally and to the
sesamoid bones proximally. With turf toe, the hyperdorsiflexion injury
disrupts the plantar plate or its attachments
[6–9].
The MRI findings of turf toe have been described only a few times
[6–9]
and include marked soft-tissue edema at the plantar aspect of the affected
metatarsophalangeal joint and a high-signal-intensity tear in the normally
low-signal-intensity plantar plate
[6–9].
In both cases of skimboarder's toe described here, the plantar plate was
normal, the soft-tissue swelling was dorsal (rather than plantar), and the
tears of the extensor expansions were dorsal.
Because both turf toe and skimboarder's toe result from acute
hyperdorsiflexion injury of the metatarsophalangeal joints, why are the
observed anatomic distribution and type of injury so different? Speculation
offers several potential explanations. Perhaps, since skimboarding is done
with the feet bare, the absence of footwear and its additional reinforcement
of the dorsal structures renders the extensor longus tendons more apt to
hyperdorsiflex and tear the extension expansion. Alternatively, since the MRI
findings for turf toe have been reported only a few times, perhaps a dorsal
component of injury is present more often than currently suspected.
At our institution, MRI of small musculoskeletal joints, including the
toes, often is performed on our 3-T unit. The findings in skimboarder's toe
were readily shown at 3 T in the two cases described here. However, there is
no reason to think that these same findings would not be seen on 1.5-T MRI
units as well.
In conclusion, the act of mounting a skimboard can be associated with
hyperdorsiflexion of the metatarsophalangeal joints. Acute hyperdorsiflexion
of the metatarsophalangeal joints can result in dorsal displacement of either
the extensor hallucis longus or the extensor digitorum longus tendon and in
disruption of the extensor expansion of the dorsal aspect of the fibrous joint
capsule. High-field MRI shows the surrounding dorsal soft-tissue edema and
disruption and laxity within the extensor expansion. This type of injury
appears to be different from turf toe, in which hyperextension of the
metatarsophalangeal joint results predominantly in injury to the plantar plate
and the associated soft-tissue swelling is plantar.
References
- www.skimonline.com.
Accessed January 16, 2005
- www.skimcity.com.
Accessed January 16, 2005
- www.skimmag.com.
Accessed January 16, 2005
- www.vicskim.com.
Accessed January 16, 2005
- Netter FH. Atlas of human anatomy. West
Caldwell, NJ: CIBA-CEIGY, 1989:498
–499
- Tewes DP, Fischer DA, Fritts HM, Guanch CA. MRI findings of acute
turf toe: a case report and review of anatomy. Clin
Orthop 1994;304:200
–203
- Ashman CJ, Klecker RJ, Yu JS. Forefoot pain involving the
metatarsal region: differential diagnosis with MR imaging.
RadioGraphics2001; 21:1425
–1440[Abstract/Free Full Text]
- Yao L, Cracciolo A, Farahani K, Seeger LL. Magnetic resonance
imaging of plantar plate rupture. Foot Ankle Int1996; 17:33
–36[Medline]
- Umas HR, Elsinger E. The plantar plate of the lesser
metatarsophalangeal joints: potential for injury and role of MR imaging.
Magn Reson Imaging Clin N Am2001; 9:659
–669[Medline]
- Watson TS, Anderson RB, Davis WH. Periarticular injuries to the
hallux metatarsophalangeal joint in athletes. Foot Ankle
Clin 2000;5:687
–713[Medline]
- Roedo SA, O'Brien S, Warren RF, et al. Turf-toe: an analysis of
metatarsophalangeal joint sprains in professional football players.
Am J Sports Med1990; 18:280
–285[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Abstract
Introduction
