Recurrent Fifth Metatarsal Fractures. Carol Frey MD Fellowship Co - Director West Coast Sports Medicine Foundation UCLA Manhattan Beach, California

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1 Recurrent Fifth Metatarsal Fractures Carol Frey MD Fellowship Co - Director West Coast Sports Medicine Foundation UCLA Manhattan Beach, California

2 General 5th MT fracture fairly common Mechanism: Hindfoot inversion Forefoot adduction Repetitive trauma

3 Osteology & Insertions Divided into tubercle (tuberosity), base, shaft, head & neck Peroneus brevis & lateral band of PF insert on the base Peroneus tertius insets on dorsal meta-diaphysis

4 Blood Supply Blood supply provided by metaphyseal vessels & diaphyseal nutrient artery Zone 2 (Jones) represents a vascular watershed area Non union rate in Zone 2 is as high as 15-30%

5 History/Exam Often an acute fracture in an athlete Varus hindfoot alignment is risk to 5th MT overload Check for prior pain (stress fracture) Manual palpation painful Pain over lateral border forefoot, especially with WB Resisted foot eversion painful R/O other injury on lateral foot/ankle such as unstable ankle

6 Hindfoot Position May Predispose to 5th MT Overload

7 Unstable Ankle May Predispose to th 5 MT Overload

8 Imaging Radiographs: AP, lateral & oblique Fracture location Extension into articulation? Displacement? Stress reaction?

9 Fracture Tuberosity

10 Jones Fracture Metaphyseal-diaphyseal junction base of 5th MT Sir Robert Jones, 1902 Dameron first to suggest more difficult to treat in athletes Higher re-fracture/delayed union/non-union rate Extensive non-weight bearing often needed Very confusing term

11 Jones v. Stress Fracture Is there a difference? Jones fracture is a confusing term Torg classification include Jones fractures but is more accurately applied to stress fractures More straight forward to classify fractures using the zones Zone two (Jones) is described as fracture at metaphsyis-diaphyseal junction, 1.5 cm from tuberosity, acute Zone 2 & 3 often confused in literature (most studies do not differentiate)

12 Zones

13 Zones Zone 1 Proximal tubercle (rarely into 5th TMT jt) Nonunion uncommon Zone 2 Metaphyseal-diaphyseal junction (Jones Fracture) Involves 4th-5th MT jt Vascular watershed area Nonunion risk 15-30% Acute injury Proximal diaphyseal Distal to 4th-5th MT jt Stress fracture in athletes Increased risk nonunion (15-30%) Risks factors Zone 3

14 Imaging CT: not routine but consider when delayed union or non union MRI: not routine but consider when delayed union or non union

15 Torg Classification Proximal part diaphysis 5th MT Based on healing potential 3 types Type I: acute visualized on x-ray as narrow fracture line, no intramedullary sclerosis Type II: delayed union on x-ray, widening fracture line and evidence intramedullary sclerosis on plain views Type III: show non-union with wide fracture line and complete medullary canal obliteration by sclerotic bone

16 Lee Classification 5th Stress Fractures Proximal part diaphysis 5th MT Group A: complete fracture had a clear fracture line from lateral to medial A1: acute A2: acute on chronic Group B: incomplete fracture limited to plantar lateral area of 5th MT w/o progression to medial/dorsal cortex B1: plantar gap <1 mm B2: plantar gap > 1 mm

17 Lee Classification

18 General 5th MT stress fractures tendency delayed union, nonunion and possible re-fracture (recurrent) Average time to heal was about 9 weeks (Wright, DeLee, Mindrebo) Average time to re-fracture (3 to 8 months) even if healing on CT (Lee) Early re-fracture implies incomplete healing

19 Risk Factors Early return to activity before complete healing (Glasgow) Aggressive Rehab (Lee) Weak toe grip strength (Haspl) Low Vit D levels (should be in athlete) Difficulty healing related to fracture location Re-fracture may be associated with higher BMI and protrusion of the 5th MT head (Lee, 2013, FAIJ)

20 Risk Factors Lee studied re-fracture after surgery BMI was correlated Operative difficulty not related Running/cutting sports may predispose Cavus foot Shape of 5th MT, increased curvature (especially on oblique x-ray) > IMA 4-5 on AP x-ray higher in re fracture group

21 Biomechanics Main pathology is at the plantar lateral side 5th MT Repetitive stress concentrated there Tensile force concentrated plantar lateral & compressive force dorsal medial Important to repair the plantar gap

22 Treatment Options Non-operative treatment with casting, protected weight bearing (WB depends on type) Intra-medullary (IM) screw fixation External bone stimulation Tension band technique/plating

23 Treatment Non-operative: protected WB (stiff shoe/cast/boot) in ZONE 1 Advance as tolerated by pain Early return to activity but symptoms may be 6 months NWB SLC 6 8 weeks Zone 2 or Zone 3 in a NON-Athlete Advance with signs of radiographic healing Operative IM screw / tension band plate Zone 2 (Jones) elite/competitive athlete Zone 3 w/ sclerosis/nonunion or competitive athlete

24 Surgical Anatomy There is a watershed area of relatively less perfusion in Zone II of the 5th MT 5th MT is a curved bone (relevant to fixation with a straight implant (screw)

25 Surgery IM screw fixation popular w/ several reports of increased union rates Many recent reports note 10% failure after screw fixation in athletes (Glasgow, Wright) Tension band has been reported to have comparable results (6-10% re-fracture v. 10%) Bone graft?

26 Non-union Re-fracture, however, occurs after even low grade fracture or even a long time after union seen Studies show may be associated with cavus foot Raikin reported varus hindfoot alignment might be predisposing to fracture & re-fracture even after surgery No comparison study has shown cause of re-fracture after surgery for 5th MT Stress Fracture

27 Complications Non-union Increased risk in Zone 2 & 3 due to vascular supply Smaller diameter screws (<4.5 mm) associated w/ delayed union or non union Failure of fixation Too small screw diameter or length Mal-reduction Screws that perforate medial cortex or are too long & straighten too much

28 Conclusions Re-fracture proximal 5th MT is known complication Higher failure rate with athletes Unacceptable high non-union, re-fracture, & delayed return to play after non-operative treatment Primary fixation is accepted standard treatment for elite athlete However, non-union & re-fracture remain common after surgical fixation also (DeLee, Glasgow, Lee, Porter)

29 Conclusion Risk of re-fracture higher in heavier patient with wide 4th-5th IM angle & curved 5th MT Longer period of protection / some form protective gear may be helpful for these patients

30 Varus Hindfoot Orthotics Help if varus hindfoot, lateral wedge Some studies say improve the sway test (balance) Takes stress off the fifth MT

31 Rehabilitation

32 Modifications

33 Cavus Foot

34 Unstable Ankle May Need Ligament Repair

35 Fifth MT Fractures Zone I, II and III of proximal 5th MT Acute fractures in an athlete Ask for pre-existing symptoms Stress injury must be ruled out High nonunion & re-fracture rate Treat lateral foot overload Protection/shoe modifications