"Helicopter" fracture JOHN A. UNGERSMA, MD, LYMAN G. MASON, MD, MICHAEL A. O’KEEFE, MD, AND OWEN R. WALKER, MD
HISTORY
lt
is a beautiful, winter day with crisp snow and blue skies. The exhilaration of all of those on the ski slopes is shared by an expert acrobatic skier as he comes down the slope at a moderate rate of speed of 15 to 25 MPH. Halfway down the slope he jumps into the air and executes a graceful 360 degree turn (&dquo;helicopter&dquo; maneuver) landing firmly on the snow and continuing his run. However, at the point of impact, he winces with pain and, shortly thereafter, is seen in the clinic. Subsequent examination reveals the presence of an essentially undisplaced, nearly transverse fracture of the fibula.
CLINICAL MATERIAL In
a
series of
over
1,000 consecutive ski
injuries seen in this clinic, approximately eight &dquo;helicopter fractures&dquo; have been seen. Four representative examples were selected and are reported herein. From the Inyo-Mono Orthopedic Clinic, Mammoth Lakes, Cal~forma. Dr. John A. Ungersma is past President, InyoMono County Medical Society, former Chief of Staff, Northern Inyo Hospital, Bishop, Califorma, and Director, Inyo-Mono Orthopedic Clinic, Mammoth Lakes, Califorma. Dr. Lyman G. Mason is Attending Staff Orthopedist, St. Mary’s Hospital, Oxnard, California; Attending Staff Orthopedist, Pleasant Valley Hospital, Camanllo, California Dr. Michael A. O’Keefe is Chief of Staff, Pleas-
Valley Hospital, Camanllo, California, Attending Staff Orthopedist, St. Mary’s Hospiant
tal, Oxnard, Califorma. Dr. Owen R. Walker is Assistant Clinical Profesof Orthopedic Surgery, University of Califorma, Los Angeles, School of Medicine; Chief, Department of Orthopedics, Northern Inyo Hospital, Bishop, California. sor
122
Classical studies discussing fractures of the fibula have for 135 years accurately described oblique fractures produced by external rotation of the foot and leg. These fractures occur in the distal end and can .nvolve the ankle joint. In his classical study written in 1840, Maisonnevel stated that the injury always occurs in the same course and in the same place in the fibula. The location he apparently was considering was the distal third. In our cases the rotational maneuver was not only present, but was dramatic and easily observed by anyone watching the acrobatic skiers. But contrary to what an orthopedist might predict, the fracture was not transverse, as described in the literature for the past numerous decades. LEVEL OF FRACTURE
Our observations of this type of fracture, again reveal a rather typical area that is involved. The fracture is more nearly transverse and rarely comminuted. The injury produced by the so called &dquo;helicopter maneuver&dquo; is a rotational maneuver performed at moderate speed while skiing. The fracture seen in this clinic occurs, in every instance, between 14 and 12.5 centimeters above the ankle joint. The authors have concluded that the fibula has various &dquo;weak points,&dquo; depending upon either the mechanism of injury, or perhaps the physical conditioning and anatomical variations present in that patient’s particular fibula. One wonders if it is true that rotation plays little part in the actual fracture, as we have been classically taught to believe. In the cases described, perhaps the rotation of the fibula was al-
Figure laa Figure I-Case I: G.G., age 28, accomplished skier, performed helicopter maneuver to the right, suffered fracture of the right fibula, reported minimal pain (a) Antero-posterior view; (b) Enlarged oblique view showing double linear, slightly oblique fractures. to a large degree by the application of firm, tight, high plastic ski boot,-the
tered a
variety most commonly petitive skiing. In other words, what is
helicopter fractures
seen
today
we are a
in
com-
describing
in
torsional injurv
torsional result. For years, those involved with athletic injuries of the skier have talked about &dquo;boot
without
a
top fractures&dquo;. Now, with varying heights of the ski boot we are relating injuries to the boot, its heighth and subsequent change in the morphology and location of fractures. However, it is our contention that the precise mechanisms of injury and possible variations in the anatomy of the individual are more productive of specific fractures than the boot which they are wearing at the time. 123
Figure The mere coincidence of a certain type of boot with an injury should not lead us to a conclusion that the boot was the cause. Monk,2in his excellent article, discusses dissections of the interosseous ligament between the tibia and fibula. Monk begins his discussion of these dissections by stating that the heighth of the tibiofibular syndesmosis varies greatly in various individuals. This variation is from 2 to 6 centimeters above the ankle joint. In our series, all the fractures occurred between 14 and 12.5 124
1b
centimeters above the ankle joint at a level corresponding to nearly twice the height of the syndesmosis formed by the tibial fibular ligament. Expressed decimally, the fractures occurred .3 to .36 of the distance from the ankle joint. This is almost exactly one-third of the distance from the tip of the fibula. Watson-Jones’ stressed the relationship of high fractures of the fibula to the tibiofibular ligaments. He did not make any mention of rotatory components. We must therefore postulate some other mechanism for pro-
Figure
Figure
2a
2-Case II : M.M., age 26, accomplished acrobatic skier, performed helicopter maneuver to the nght, sustained fracture of nght fibula, expenenced moderate discomfort but could continue skiing. (a) Anteropostenor view; (b) Lateral view showing minimal comminution of an essentially transverse fracture.
ducing the
transverse distal third fibular
fracture. POSSIBLE MECHANISM OF INJURY
The skier
performs
a
high speed
rotation
while elevated above the ground. He strikes the ground with the foot in marked equinus for this is the position maneuver
maintained by all modern high-competitive ski boots. The force of the deceleration dorsiflexes the foot which causes the talus to apply energy to the distal end of the fibula whereas the proximal end is fixed by the ligaments above the knee joint with the knee in slight flexion. The force is transmitted along the long axis of the fibula to its 125
Figure
2b
anatomical weak portion (our isthmus). In One is at the top of the tibiofibular ligament, measuring a number of fibulas, including which, according to Monk, does not extend those reported herein, one can delineate an more than 2 to 6 centimeters above the ankle isthmus of the fibula which is quite a bit joint. This would describe the fracture mech-
above the interosseous tibiofibular ligament. We feel that the fibular shaft exceeds its elastic limit at this point and probably bends medially or later ally in a brief period producing the short fracture described. In other words, we postulate that there are at least two anatomical weak spots of the fibula. 126
anism about the ankle joint. The second anatomical weak spot would be at the isthmus of the fibula (described radiographically) which occurs almost exactly at one-third above the ankle joint or two-thirds from the proximal end. There is in itself no real relationship to the heighth of
Figure
Figure 3a 16, competitive high-speed
3-Case III B.H., age racing skier, performed helicopter maneuver to the left, sustained fracture of left fibula, unable to complete his run. (a) Anteroposterior view; (b) Lateral view showing no displacement and minimal comminution
the boot. The mechanism we postulate is not of levering over the edge of the boot, but rather a force being transmitted along the long axis of the fibula. The fact that there is one
enough energy in skiing maneuvers to produce this type of sharp compression and transverse fracture is pointed out by Clayton4 who states that at 30 miles per
hour, 6600 pounds of energy are produced on the legs by an instantaneous stop. Our athletes
going down hill at high speed, produced considerable velocity depending on the heighth above the snow when they performed a helicopter maneuwere
not
but
ver,-this in addition
ity
to
their linear veloc-
at take-off.
127
Figure Some weight is given to this hypothesis by Lambert’ who is able to show that the fibula is a weight-bearing bone. Hence, we feel that the concept of the fibula as a splint only, or as a clevis for the ankle, or as an outrigger for the origin and insertion of muscles is not the full story. We would agree with Lambert that the fibula is assigned a fourth function, that of weight-beanng. In peculiar bodily functions or motions, such as described in this article, the fibula definitely transmits a portion of the body’s weight and hence can 128
3b
injured in its own unique way independently of the tibia. In his experiments, Lambe
bert incised the interosseous membrane before and after loading the tibia and fibula. He found that the intact interosseous membrane has little effect on the measurements. He felt that the membrane may serve to prevent bowing of the fibula and, therefore, may allow the fibula to weave or to serve as a beam in shoring up the postero-lateral surface of the tibia. He concluded that in his biostatic model, one-sixth of the static load,
Figure Figure
4a
4-Case IV: J.M., age 41, experienced high-speed skier, performed helicopter maneuver to the right, fractured right fibula, was able to continue skiing (a) Antero-postenor view showing barely discernibly, minimally comminuted, transverse fracture of the fibula; (b) Enlarged view showing no real displacement.
the leg was carried by the fibula. If we apply this figure to Clayton’s figures of 6600 pounds in a 30 MPH stop, we find that this amounts to 1100 foot pounds which conceivably could be transmitted to only one fibula as the skier performing the helicopter maneuver must, understandably, land on one on
foot first. This adds up to an impressive 2200 foot pounds of energy being transmitted to that particular fibular shaft.
One other possible mechanism of injury be explored to explain why these fractures all occurred in highly trained competitive, active athletes. Could we be seeing stress fractures of the fibula? Devis and Sweetnaml describe a series of fifty stress fractures (in athletes) of the fibula. The great preponderance of their fractures occurred in the lower third of the fibula at a level 4 centimeters above the can
129
Figure
joint. This level corresponds very accurately to that level served by the interosseous membrane. Devis and Sweetnam made
the foot, it is our opinion that we are not with stress fractures of the fibula.
dealing
a
biologic model and contracted the calf muscles by plantar flexing the foot. They were able to demonstrate radiographically that the distal third of the fibula moves towards the tibia with plantar flexion. It is quite conceivable that dorsiflexion of the foot would produce the opposite movement forcing the fibula away from the tibial shaft and enabling the force to be transmitted quite precisely along its course. Therefore, since our patients suffered severe dorsiflexion of 130
4b
SUMMARY
An interesting fracture of the fibula is described which occurs very close to the radiographic isthmus of the bone. This fracture is produced by a rotational maneuver but does not result in a rotational type injury. It is our conclusion that these fractures were produced by a force distributed along the long axis of the fibula and bear a direct relationship to that fibula’s anatomical ability or inability to transmit the force
required of it at the moment of forcible dorsiflexion of the foot.
ries, 4th Edition Vol. II, pg. 823, Edinburgh and London, ENS Livingstone 4.
References 1.Malsonneve JGT Recherches sur la fractur Duperone Paris, F Loquin and Cie. Arch gen de med 1 165, 433, 1840 2. Monk CJE. Injuries of the Tibial Fibular Ligaments. J Bone and joint Surg, 51-B 330, 1969 3. Watson-Jones Sir R: Fractures and Jomt Inju-
Limited, 1969 Clayton ML 52 56, 1962
Ski
Injuries.
Clin
Orthop
23.
5. Lambert KL: The Weight Bearing Function of the Fibula. J Bone and Joint Surg, 53-A, 3: 507, 1967 6. Devis MB, Sweetnam R. Stress Fractures of the Fibula, a Review of Fifty Cases in Athletes J Bone and Joint Surg, 38-B
818-829, 1956
131
HISTORY
lt
is a beautiful, winter day with crisp snow and blue skies. The exhilaration of all of those on the ski slopes is shared by an expert acrobatic skier as he comes down the slope at a moderate rate of speed of 15 to 25 MPH. Halfway down the slope he jumps into the air and executes a graceful 360 degree turn (&dquo;helicopter&dquo; maneuver) landing firmly on the snow and continuing his run. However, at the point of impact, he winces with pain and, shortly thereafter, is seen in the clinic. Subsequent examination reveals the presence of an essentially undisplaced, nearly transverse fracture of the fibula.
CLINICAL MATERIAL In
a
series of
over
1,000 consecutive ski
injuries seen in this clinic, approximately eight &dquo;helicopter fractures&dquo; have been seen. Four representative examples were selected and are reported herein. From the Inyo-Mono Orthopedic Clinic, Mammoth Lakes, Cal~forma. Dr. John A. Ungersma is past President, InyoMono County Medical Society, former Chief of Staff, Northern Inyo Hospital, Bishop, Califorma, and Director, Inyo-Mono Orthopedic Clinic, Mammoth Lakes, Califorma. Dr. Lyman G. Mason is Attending Staff Orthopedist, St. Mary’s Hospital, Oxnard, California; Attending Staff Orthopedist, Pleasant Valley Hospital, Camanllo, California Dr. Michael A. O’Keefe is Chief of Staff, Pleas-
Valley Hospital, Camanllo, California, Attending Staff Orthopedist, St. Mary’s Hospiant
tal, Oxnard, Califorma. Dr. Owen R. Walker is Assistant Clinical Profesof Orthopedic Surgery, University of Califorma, Los Angeles, School of Medicine; Chief, Department of Orthopedics, Northern Inyo Hospital, Bishop, California. sor
122
Classical studies discussing fractures of the fibula have for 135 years accurately described oblique fractures produced by external rotation of the foot and leg. These fractures occur in the distal end and can .nvolve the ankle joint. In his classical study written in 1840, Maisonnevel stated that the injury always occurs in the same course and in the same place in the fibula. The location he apparently was considering was the distal third. In our cases the rotational maneuver was not only present, but was dramatic and easily observed by anyone watching the acrobatic skiers. But contrary to what an orthopedist might predict, the fracture was not transverse, as described in the literature for the past numerous decades. LEVEL OF FRACTURE
Our observations of this type of fracture, again reveal a rather typical area that is involved. The fracture is more nearly transverse and rarely comminuted. The injury produced by the so called &dquo;helicopter maneuver&dquo; is a rotational maneuver performed at moderate speed while skiing. The fracture seen in this clinic occurs, in every instance, between 14 and 12.5 centimeters above the ankle joint. The authors have concluded that the fibula has various &dquo;weak points,&dquo; depending upon either the mechanism of injury, or perhaps the physical conditioning and anatomical variations present in that patient’s particular fibula. One wonders if it is true that rotation plays little part in the actual fracture, as we have been classically taught to believe. In the cases described, perhaps the rotation of the fibula was al-
Figure laa Figure I-Case I: G.G., age 28, accomplished skier, performed helicopter maneuver to the right, suffered fracture of the right fibula, reported minimal pain (a) Antero-posterior view; (b) Enlarged oblique view showing double linear, slightly oblique fractures. to a large degree by the application of firm, tight, high plastic ski boot,-the
tered a
variety most commonly petitive skiing. In other words, what is
helicopter fractures
seen
today
we are a
in
com-
describing
in
torsional injurv
torsional result. For years, those involved with athletic injuries of the skier have talked about &dquo;boot
without
a
top fractures&dquo;. Now, with varying heights of the ski boot we are relating injuries to the boot, its heighth and subsequent change in the morphology and location of fractures. However, it is our contention that the precise mechanisms of injury and possible variations in the anatomy of the individual are more productive of specific fractures than the boot which they are wearing at the time. 123
Figure The mere coincidence of a certain type of boot with an injury should not lead us to a conclusion that the boot was the cause. Monk,2in his excellent article, discusses dissections of the interosseous ligament between the tibia and fibula. Monk begins his discussion of these dissections by stating that the heighth of the tibiofibular syndesmosis varies greatly in various individuals. This variation is from 2 to 6 centimeters above the ankle joint. In our series, all the fractures occurred between 14 and 12.5 124
1b
centimeters above the ankle joint at a level corresponding to nearly twice the height of the syndesmosis formed by the tibial fibular ligament. Expressed decimally, the fractures occurred .3 to .36 of the distance from the ankle joint. This is almost exactly one-third of the distance from the tip of the fibula. Watson-Jones’ stressed the relationship of high fractures of the fibula to the tibiofibular ligaments. He did not make any mention of rotatory components. We must therefore postulate some other mechanism for pro-
Figure
Figure
2a
2-Case II : M.M., age 26, accomplished acrobatic skier, performed helicopter maneuver to the nght, sustained fracture of nght fibula, expenenced moderate discomfort but could continue skiing. (a) Anteropostenor view; (b) Lateral view showing minimal comminution of an essentially transverse fracture.
ducing the
transverse distal third fibular
fracture. POSSIBLE MECHANISM OF INJURY
The skier
performs
a
high speed
rotation
while elevated above the ground. He strikes the ground with the foot in marked equinus for this is the position maneuver
maintained by all modern high-competitive ski boots. The force of the deceleration dorsiflexes the foot which causes the talus to apply energy to the distal end of the fibula whereas the proximal end is fixed by the ligaments above the knee joint with the knee in slight flexion. The force is transmitted along the long axis of the fibula to its 125
Figure
2b
anatomical weak portion (our isthmus). In One is at the top of the tibiofibular ligament, measuring a number of fibulas, including which, according to Monk, does not extend those reported herein, one can delineate an more than 2 to 6 centimeters above the ankle isthmus of the fibula which is quite a bit joint. This would describe the fracture mech-
above the interosseous tibiofibular ligament. We feel that the fibular shaft exceeds its elastic limit at this point and probably bends medially or later ally in a brief period producing the short fracture described. In other words, we postulate that there are at least two anatomical weak spots of the fibula. 126
anism about the ankle joint. The second anatomical weak spot would be at the isthmus of the fibula (described radiographically) which occurs almost exactly at one-third above the ankle joint or two-thirds from the proximal end. There is in itself no real relationship to the heighth of
Figure
Figure 3a 16, competitive high-speed
3-Case III B.H., age racing skier, performed helicopter maneuver to the left, sustained fracture of left fibula, unable to complete his run. (a) Anteroposterior view; (b) Lateral view showing no displacement and minimal comminution
the boot. The mechanism we postulate is not of levering over the edge of the boot, but rather a force being transmitted along the long axis of the fibula. The fact that there is one
enough energy in skiing maneuvers to produce this type of sharp compression and transverse fracture is pointed out by Clayton4 who states that at 30 miles per
hour, 6600 pounds of energy are produced on the legs by an instantaneous stop. Our athletes
going down hill at high speed, produced considerable velocity depending on the heighth above the snow when they performed a helicopter maneuwere
not
but
ver,-this in addition
ity
to
their linear veloc-
at take-off.
127
Figure Some weight is given to this hypothesis by Lambert’ who is able to show that the fibula is a weight-bearing bone. Hence, we feel that the concept of the fibula as a splint only, or as a clevis for the ankle, or as an outrigger for the origin and insertion of muscles is not the full story. We would agree with Lambert that the fibula is assigned a fourth function, that of weight-beanng. In peculiar bodily functions or motions, such as described in this article, the fibula definitely transmits a portion of the body’s weight and hence can 128
3b
injured in its own unique way independently of the tibia. In his experiments, Lambe
bert incised the interosseous membrane before and after loading the tibia and fibula. He found that the intact interosseous membrane has little effect on the measurements. He felt that the membrane may serve to prevent bowing of the fibula and, therefore, may allow the fibula to weave or to serve as a beam in shoring up the postero-lateral surface of the tibia. He concluded that in his biostatic model, one-sixth of the static load,
Figure Figure
4a
4-Case IV: J.M., age 41, experienced high-speed skier, performed helicopter maneuver to the right, fractured right fibula, was able to continue skiing (a) Antero-postenor view showing barely discernibly, minimally comminuted, transverse fracture of the fibula; (b) Enlarged view showing no real displacement.
the leg was carried by the fibula. If we apply this figure to Clayton’s figures of 6600 pounds in a 30 MPH stop, we find that this amounts to 1100 foot pounds which conceivably could be transmitted to only one fibula as the skier performing the helicopter maneuver must, understandably, land on one on
foot first. This adds up to an impressive 2200 foot pounds of energy being transmitted to that particular fibular shaft.
One other possible mechanism of injury be explored to explain why these fractures all occurred in highly trained competitive, active athletes. Could we be seeing stress fractures of the fibula? Devis and Sweetnaml describe a series of fifty stress fractures (in athletes) of the fibula. The great preponderance of their fractures occurred in the lower third of the fibula at a level 4 centimeters above the can
129
Figure
joint. This level corresponds very accurately to that level served by the interosseous membrane. Devis and Sweetnam made
the foot, it is our opinion that we are not with stress fractures of the fibula.
dealing
a
biologic model and contracted the calf muscles by plantar flexing the foot. They were able to demonstrate radiographically that the distal third of the fibula moves towards the tibia with plantar flexion. It is quite conceivable that dorsiflexion of the foot would produce the opposite movement forcing the fibula away from the tibial shaft and enabling the force to be transmitted quite precisely along its course. Therefore, since our patients suffered severe dorsiflexion of 130
4b
SUMMARY
An interesting fracture of the fibula is described which occurs very close to the radiographic isthmus of the bone. This fracture is produced by a rotational maneuver but does not result in a rotational type injury. It is our conclusion that these fractures were produced by a force distributed along the long axis of the fibula and bear a direct relationship to that fibula’s anatomical ability or inability to transmit the force
required of it at the moment of forcible dorsiflexion of the foot.
ries, 4th Edition Vol. II, pg. 823, Edinburgh and London, ENS Livingstone 4.
References 1.Malsonneve JGT Recherches sur la fractur Duperone Paris, F Loquin and Cie. Arch gen de med 1 165, 433, 1840 2. Monk CJE. Injuries of the Tibial Fibular Ligaments. J Bone and joint Surg, 51-B 330, 1969 3. Watson-Jones Sir R: Fractures and Jomt Inju-
Limited, 1969 Clayton ML 52 56, 1962
Ski
Injuries.
Clin
Orthop
23.
5. Lambert KL: The Weight Bearing Function of the Fibula. J Bone and Joint Surg, 53-A, 3: 507, 1967 6. Devis MB, Sweetnam R. Stress Fractures of the Fibula, a Review of Fifty Cases in Athletes J Bone and Joint Surg, 38-B
818-829, 1956
131
