Download Classification and Treatment of Fifth Metatarsal Fractures: A Comprehensive Review and more Study notes Medicine in PDF only on Docsity!
TRAUMA 0891-8422/95 $0.00 +.
FIFTH METATARSAL FRACTURES Biomechanics, Classification, and Treatment
Harold W. Vogler, DPM, Nils Westlin, MD, PhD,
Alan J. Mlodzienski, DPM, and Finn Bojsen Moller, MD, PhD Fracture of the fifth metatarsal is a commonly encountered podiatric ortho- pedic clinical event.': 4, 8, 15, 17, 19, 22, 25, 29 The statistical frequency for all types of fifth metatarsal fractures collectively compared against other foot fractures is unknown, Two recent studies from one of the author's Institutions (NW) have identified the proximal junctional diaphyseal-metaphyseal Jones fracture fre- quency rate as 0.7%-1.9% in a combined total of 10,988 foot fractures.lv P Classification of the different forms of fifth metatarsal fracture primarily are based on anatomic location and fracture personality, The tuberosity and proxi- mal junctional diaphyseal fractures have received the most attention in the literature owing to the confusion regarding the most effective form of treat- ment.>3, 4, 5, 11, 15, 16, 17, 20, 29 The distal capitak.cervical, and shaft fractures are less controversial with regard to treatment concepts, but review of the literature also demonstrates considerable variation in treatment methods for these fractures. Surgeon preference, training, and patient-related parameters playa role in the decision for various forms of treatment as welL This article defines a classification system for fifth metatarsal fractures based on anatomic site, time of encounter, and fracture morphology, and uses this model to direct the surgeon toward an appropriate method of treatment. Addi- tionally, the biomechanics of the fifth metatarsal segment and its interactions are explored to help the clinician understand how fracture occurs within this bone. The biomechanical behavior of this segment and its attachments can be From the Foot and Ankle Medical Center, Tampa, Florida (HWV), and the Panum Institute of the University of Copenhagen, Copenhagen, Denmark (HWV, FBM); Malmo Gen- eral Hospital, Malmo, Sweden (HWV) (NW); and the Presbyterian Medical Cente.r, and the Pennsylvania College of Podiatric Medicine, Philadelphia, Permsylvarua (AM,HWV) CLINICS IN PODIATRIC MEDICINE AND SURGERY VOLUME 12 • NUMBER 4 • OCTOBER 1995 725
726 VOGLERet al used to help the surgeon understand treatment concepts within the classifica- tion scheme, ANATOMY AND BIOMECHANICS The fifth metatarsal functions with an independent axis of motion." The direction and range of motion are determined by orientation of its, axis an~ by ,its ligamentous and tethering soft tissue attachments, These factors dictate primarily dorsiflexion and plantarflexion with inversion-eversion a,s the potential move- ments of this segment." Strong plantar ligaments extendmg from the os calc,ls span the cuboid to insert at the plantar fifth metatarsal base:^23 A small cub?td fifth metatarsal ligament is present at the undersurface to remforce the tension surface of this joint, as is a small slip of plantar fascia." An interosseous ligament locks the base against the fourth metatarsal.l"" A dorsal cuboid fifth metatarsal ligament spans the top of the proximal joint to promote dorsal stability.w " The peroneus brevis attachment at the tuberosity base provides a powerful dynamic tensile loading capacity with some posterior axial compression as a result of its longitudinal course from the fibular malleolus to the metatarsal base, The contribution to joint stability from peroneus tertius is minimal, as its course emanates proximally and is dosiflexory. It fires during swing phase and brieflv at heel contact phase of gait. Fracture of the fifth metatarsal does not occur during swing or early stance phase; however, a small medial compressive load against the fourth metatarsal is possible with this orientation. The fifth metatarsal is cradled with muscle investitures from the flexor digiti quinti brevis arising from the plantar base region, which sometimes extend more distally to insert laterally on the shaft as well as on the lateral fifth proximal phalanx: 111' abductor digiti minimi may have a small insertion on the base of the fifth metatarsal and, occasionally, on the mid-shaft as it progresses toward its fin., insertion on the base of the proximal phalanx.' As such, it could help cradle this segment laterally and perhaps biomechanically. Intermetatarsal stability is aided by the fourth dorsal interosseous muscle, which originates from both the medial fifth metatarsal shaft and base and from the adjacent area of the lateral fourth metatarsal. The plantar interosseous muscle has no substrate on the fourth metatarsal or the proximal links and thus plays no role in stabilizing the base, The morphology of the bone demonstrates a longitudinal dorsal convexity, lik, the other metatarsals, to help neutralize bending moments (flexural neutralize- tion) in the loaded closed kinetic chain state. It is the terminal link of the outer part of lateral column of the foot, completing a curved segmented beam link.1"" for~ed by the ~ompani~:m compo~ents of the os calcis and cuboid. Its design . defmed by a, distal ar~cular capital segment, a narrowed cervical region th.! becomes continuous WIth a dense cortical midregion or shaft with an isthmus The isthmus ~as surgical significance for osteosynthesis medullary axial fixation pro~edures ~Imilar to the, t~bial isthm,us; this is discussed subsequently. Proc- ressmg proxImally: a transition occurs mto a metaphyseal expansion, terminatinc at t~e most pr~x1.~nal ~nd, lateral ends with a narrow tuberosity. The~ .1r~' coru:;rder~ble :,ar~a~Ions m SIze and shape.' These anatomic design changes have engmeermg significance for load acceptance. Loading of the fifth metatarsal segment under ordinary gait mechanics i- generat~d t~rough a, combined mechanism of induced compression f~om' it- compamon lmks proximally and from distal gravitational forces at the m t t. I h ea. d Loa d (^) accep t (^) ance depen ds (^) on intact'^ mtegrity,^ of the interface segmee at^ .1rs.,I so ft^ tiIssue^ a tt^ ach men t^ S.·^29 32 M^ or bid 1 I^ oadmg'^ occurs during competitive athleticsn^ s^ In,
728 (/J
z
o
o
I- Z LlJ
LlJ a: l- I I- 3 (/J LlJ a: ::J I-
o
a: LL -I
«(/J
a:
S
LlJ
LL
o
Z
o
o
u::: (j) (/J
:s
o o ~ ~ z «
LLLL
a: a:
00
"E"E Ol Ol
E E coco
g~
"0 Ol "0Ol CIl 00 CIl
c"E OlOl
EE caCti OlOl ~J= "0"0 OlOl CIlCll 00
c: o
~tJ
...I^ o Ol Ol
s
.
c.CIl
.~ :>::: cOl cOl E E ttl ttl
~ g
"0 Ol "0Ol CIl o CIl 0
o 0
E E 6 C\i
o
Ol Ol .l . C.CIl CIl 3: Ol Ol .:: t;
:r CIl
:>:::
cOl cOl
E E
co 10
"0 Ol "0Ol o^ CIl^ CIl 0
o 0
Ol g'
·
o
~o
1Il E Ol E.!::: 63: C\i
~o
CIl E E ,;., -.i LL
a:
o 1Il>- Ol;:: -Ol .!!1"O .J:::- -Ol ctl ~ ~ 0 0- -" c OJ Ol1Il e.^0 00 E OJ E ttl
"0"0 Ol OJ CIl 1Il 00
"0 C ctl . _c co ~.~ -OJ ctl- Ol OJ
Ole. CIl .2O 0-1^0 .0. 00 E E .5. OJ OJ
c.c.
EE "00 " "0 OlOl " 1Il1ll 00
FfFTH METATARSAL FRACTURES 729 Figure 2. Comminuted capitum fifth metatarsal fracture with companion fourth metatarsal cervical fracture, in satisfactory alignment for closed treatment. Figure 3. "Dancer's fracture" of the fifth metatarsal cervical neck region. This is usually a spiral fracture that heals well with closed treatment, unless the patient is a competitive athlete or performer.
FlFTH MFrATARSAL FRACJl.JRfS 731 Fi~u~e5.,"Dancer's fracture" internally fixed with double 2,0 mm compression lag screws, This ISfaIrly easy owing to the long spiral surfaces. ~atigue,,or chronic nonunion with medullary sclerosis.v'v 17.23.31.33This fracture ISnotOrIOUS for prolonged healing and nonunion. I, 2. S. 100-14, 16, 17,20, 23. 31), 33 As a result, surgery has become the accepted norm and common for the athlete and ~thers who desire more rapid rehebtlitation.'>' •. 16, 20, 30. 33 Medullary screw fixa- tion has emerged as the technique of choice for acute or fatigue-related failurev 14,1~,18, 20 (Fig. BA,B). Cannulated screws have taken this concept a step further owmg to their greater ease of insertion (Fig. 9). TUberosity The styloid process at the fifth metatarsal base as well as its more distal metaphyseal expansion form the proximal tuberosity flare." Its rigid attachments of ligaments, tendons, and capsule make it a very stable substrate that is locked firmly against its counterparts-the cuboid and fourth metatarsal base. There is a,lmost total agreement regarding the pathomechanics of fracture through this slte.<Il·17,19.22-24,29Avulsions represent tensile mediated overloads via traction from the various ligaments and dynamics of the peroneus brevis tendon during inversion and plantar flexion movements.22.24.31The avulsions are often irregular but are small and virtually always include portions of the insertion of the peroneus brevis and the plantar ligament or fascia insertions (Fig. 10). These fractures must be assessed carefully in adolescents who have a secondary growth plate^4 •^29 (Fig. 11). The significant features of concern with this fracture relate to whether it enters the cuboid joint and the amount of distraction present- 17,D, 29 (Fig. 12). It can also be almost transverse, where it enters the intermetatarsal joint (Fig. 13). The forces operational for this pattern are a frictional. pivot, ~ilh the heel elevated in conjunction with external leg and talar rotation creating adduction at the midfoot and hindfoot, with the forefoot fixed during perfor- mance. The tensile overload is directed through the peroneus brevis, the lateral
732 VOCLER et a Figure 6. A, Comminuted fifth metatarsal fracture from low velocity missle impact. Segmen. tal distortion is present near the "junctional" region and base. B, Intraoperative situation, repairing the larger comminutions with 2.0 mm screws to prepare for external fixation buttress stabilization. C. Final stabilization with mini AQ external fixator and carbon rod. lIfustration continued on opposite page
734 VOGLER et al Figure 7. Classic "junctional" fresh Jones fracture with comminuted butterfly fragment. Figure 8. A, Stress Jones fracture in a young soccer athlete. B, Repaired with 4.5 mm AO axial medullary malleolar screw.
FIFTH METATARSAL FRACTURES 735 Figure 9. ACE (ACE Medical Company, EI Segundo, California) 4.5 titanium lag screw, cannulated delivery on skeletal model. Figure 10. Small tuberosity avulsion fractures resulting from dynamic traction from the ~eroneus brevis and long plantar ligament slip. This heals well with minimal immobiliza- tion treatment. Figure 11. Intra-articular tuberosity fracture, nondisplaced, with a small secondary growth center at its classic location.
FIfTH METATARSAL FRACTURES 737 Figure 14. Comminuted "dancer's" cervical fracture fixed with three interfragmentary 2. mm lag screws. of the fragments with conversion to an arthroplasty is usually the best option. Small plates have poor bone purchase in this subcutaneous area and are not recommended. Cervical fractures or infractions can be managed using closed reduction with distraction techniques under local anesthesiev v 17 (see Fig. 2). If there is significant angulation or sagittal plane malalignment, then open reduction is required. This can be accomplished in perferential manner as all these fractures heal well. Techniques available include simple insertion of interfragmentary 2.0- m.m lag screws for spiral orientations (Fig. 14), use of medullary splintage pins entering the distal lateral metatarsal head sliding down the medial cortical metatarsal wall (Fig. 15A,B,C,D), and placement of monofilament wire loops.16, 17, 21_23, 31 Plates are the Jeast desirable option in this location unless there is segmental loss that requires interposition bone grafting. Shaft fractures can be managed using the same concepts as cervical frac- tures. Medullary splintage is simple and effective with Kvwires" 16,31 (Fig. 16). Plates can be used in this area because there is adequate bone mass for purchase, but they are usually reserved for comminutions or segmental Joss." Occasion- ally, external fixation is needed as a temporary construct until more suitable circumstances permit conventional osteosynthesis link-up (see Fig. 6C-D). junctional fracture, or Jones fracture, is the most celebrated injury of the fifth metatarsal (Fig. 17).1,2,3,5,6,10--16.18--20,29,30,33 It has been recognized as a problem since the time of its original description by Jones in 1902.II The optimal form of treatment for this fracture and its natural history over time are unclear. Torg has drawn attention to the healing difficulties of this fracture and proposed In-laid bone grafting for the sclerotic delayed and nonunion situations.IS. 30, 33 The best choice for primary treatment has remained somewhat confusing. Kava- naugh et al and Delee et al have popularized medullary 4.5-mm A-O malleolar screw fixation as the primary treatment of choice for competitive athletes and other active individuals- 14 (Fig. 18).Two recent Swedish studies by [osefsson et
738 VOCLERet al Figure 15. A, "De-gloving" injury with open fracture of the fourth and fifth metatarsals with comminution. The fifth metatarsal is a cervical fracture and the fourth a comminuted shaft fracture. This is a motorcycle injury. B, The radiographic appearance demonstrating cervical fifth metatarsal fracture and comminution of the fourth metatarsal shaft. Illustration continued on opposite page al agree. They also defined the natural history of this injury with surgical and nonsurgical courses of treatment with their outcomes.!" 13 The Swedish studies represent the largest series and most extensive analysis of Jones fractures in the world literature. From this study, it is clear that in most cases the Jones fracture will uJtimately heal with nonsurgical means if given enough time. Twenty percent of these fractures can be expected to undergo delayed union or refracture with nonsurgical treatment. Kavanaugh et at reported 66% delayed union and
740 VOGLERet al Figure 16. Classic medullary splintage for shaft fracture. Figure 11. Acute Jones fracture in classic location.
FIFTH METATARSAL FRACTIJRES 741 L1H -A" Figure 18. Healed Jones fracture with 4.5 mm AD axial medullary compression screw. required, whereas Delee et al" believe axial compression screw alone is effective. Clearly, axial compression screw fixation is easier and may represent a better method of treatment, even for chronic nonunions. Thus, current recommendation for treatment of the acute or stress-related Jones fracture is insertion of medullary lag screws (4.5-mm cannuLated titanium screws) for the active patient. If the medullary canal and isthmus are small, a 4.0-mrn lag screw with washer can be used. If the site is very sclerotic, consider- ation should be given to an inlaid Torg bone graft; alternatively, a local bone graft with an axial compression 4.5-mrn cannulated titanium screw can be used. Non-weight-bearing casting can be considered for high-risk patients and those with no particular urgency for recovery." 14, 30 In the event of delayed union Figure 19. Anatomic model demonstrating ACE (ACE Medical Company, EI Segundo, California) 4.5 mm titanium cannulated lag screw axial delivery.
FIFTH METATARSALFRACTURES 743 Figure 21. A, Very small tuberosity avulsion fracture representing a traction fracture from the peroneus brevis tendon. B, Small fragments containing the peroneus brevis insertion can be captured by a "loop wire" without K-wire splintage pins.
744 VOGLERet al Figure 22. A, Oblique avulsion fragment, partially displaced, nonarticular. B, Tension banding of prior avulsion fragment, with splintage pins.
