What You Should Know About Navicular Stress Fractures
Once considered a rare form of stress fractures, navicular stress fractures are being diagnosed in an increasing number of patients. Accordingly, these authors offer diagnostic insights, a pertinent case study and a thorough review of the literature.
Towne and colleagues first described the stress fracture of the tarsal navicular in humans in a 1970 case study.1 Early studies showed that tarsal navicular stress fracture was a rare injury, accounting for only 0.7 to 2.4 percent of all stress fractures.2 However, as awareness of the injury has increased, so have the reported number of cases with tarsal navicular stress fractures currently representing up to 25 percent of stress fractures in some series.3-7
The diagnosis of navicular stress fractures is challenging as routine radiographs often fail to demonstrate the fracture. One must maintain a high index of suspicion for this injury, especially in athletes with foot pain, given the vague complaints and potential for considerable delay in diagnosis.8
The “boat shaped” navicular represents the base of the medial column of the foot, articulating with the talus proximally, and with the cuboid and all three cuneiforms distally.8,9 The navicular has several important ligamentous attachments, including the posterior tibial tendon on the medial tuberosity and the spring ligament on the plantar surface.8,9
The navicular derives its dorsal blood supply from a branch of the dorsalis pedis artery while the plantar surface receives its supply from the branches of the medial plantar artery.9 These branches form a rich anastomosis but leave the central one-third of the navicular relatively avascular.8,9 The navicular is subject to intense compressive forces over its middle one-third during the foot-strike phase of gait when it is compressed between the talus and the cuneiforms.10 Torg proposed that repetitive cyclical loading of the navicular could lead to a stress fracture over the central one-third of the navicular.11
What You Should Know About The Clinical Presentation And Physical Examination
Patients most often present with dorsal foot pain of insidious onset. Patients may initially describe the pain as soreness or cramping along the dorsomedial border of the foot, which is exacerbated by activity.8,10 As many patients who sustain navicular stress fractures are athletes, they initially may complain of pain only during sport and not with other activities of daily living.8,10 Specifically, explosive activities such as jumping, sprinting and rapidly changing direction may exacerbate symptoms.8,10
The physical examination is often unremarkable. Patients may have tenderness to palpation over the navicular. Provocative testing includes having the patient hop on the affected foot to determine if it reproduces the symptoms experienced during athletic play.8,10
Key Diagnostic Insights
The diagnostic workup should begin with plain radiographs of the standing foot and ankle. The radiographs may demonstrate a visible fracture line. However, several authors have found a high rate of false negative radiographs.3,11,12 If there remains a high index of suspicion after negative plain radiographs, further workup with bone scan, computed tomography (CT) or magnetic resonance imaging (MRI) is indicated.
Although bone scan has a high sensitivity, it is also non-specific and requires additional diagnostic testing in the event of a positive test, further delaying the definitive diagnosis.11 Bone scans are unable to differentiate navicular pathology from other possible etiologies, including a painful accessory navicular, posterior tibial tendonitis, tarsal coalition, anterior tibial tendonitis and osteochondral defects of the talus.8
Researchers have found a CT scan to be the most sensitive and specific test for the diagnosis of navicular fractures although MRI is better suited for navicular stress fractures.8,11
What The Studies Reveal About Cast Immobilization
The proper treatment of navicular stress fractures has been a recent topic of debate. Historically, conservative treatment in a non-weightbearing cast has been the treatment of choice.1,3,8,11 More recently, authors have described open reduction and internal fixation (ORIF) for navicular stress fractures.7,8,12-14
Torg and colleagues retrospectively reviewed 21 cases of navicular stress fracture and demonstrated that these stress fractures heal well with conservative treatment.11 Since routine radiographs failed to show the fracture, the interval between the onset of symptoms and diagnosis ranged from less than one month to 38 months (a mean of seven months).11 Conservative treatment in this series consisted of non-weightbearing cast immobilization for six to eight weeks, which was followed by gradual weightbearing in a boot for two to six weeks until patients were pain free.
Several authors have confirmed the efficacy of this treatment protocol.5,12,15 Even in patients who have failed treatment in a weightbearing cast, the use of a non-weightbearing cast treatment compares favorably with surgical treatment.12
Khan and colleagues studied 86 patients with navicular stress fractures and found that initial non-weightbearing cast immobilization for at least six weeks facilitated a return to sports in 19 of 22 patients (86 percent).12 In contrast, of those who initially continued weightbearing with limited activity, only 9 of 34 patients (26 percent) returned to sports. For patients who failed initial treatment, six of 7 patients (86 percent) treated with subsequent non-weightbearing cast immobilization achieved a successful outcome compared to 11 of 15 patients (73 percent) who underwent surgical treatment.
There is strong evidence supporting the effectiveness of proper conservative management for both partial and non-displaced complete stress fractures of the tarsal navicular.
Case series or reports from Ostlie, Alfred, Murray, Towne, Goergen, Ariyoshi, Miller and Ting all reported a 100 percent success rate when utilizing at least six weeks of non-weightbearing management.1,16-22 The data also strongly reaffirms that weightbearing rest or limited activity as a conservative treatment often leads to an unsuccessful outcome including: delayed union or nonunion, re-fracture, fracture progression or recurrence of symptoms.1,5,11,12,15,23,24
Weighing Surgical Versus Conservative Management
However, it appears that current management of this injury more frequently utilizes surgical intervention both as a first-line treatment or following failed treatment with conservative weightbearing management due to pressure on both the athlete and the physician to have the athlete return more quickly to competition.5,15
In a retrospective review in 2000, Saxena and colleagues studied 22 patients who sustained navicular stress fractures during athletic activity.26 For the nine patients who underwent ORIF, the average return to activity was 3.1 months. For the 13 patients treated with conservative care, the average return to activity was 4.3 months. The authors suggested that surgical intervention will decrease the amount of time for an athlete to return to his or her activity level prior to injury.
However, the most recently reported data by Saxena and colleagues in 2006 demonstrated no significant difference between surgical and conservative management for navicular stress fractures when it came to return to activity.27 According to the prospective study, patients with type 1 navicular stress fractures received non-operative treatment while patients with type 2 and type 3 injuries received ORIF. The return to activity for patients with type 1 injuries was 3.8 months whereas the return to activity for patients with type 2 fractures and type 3 fractures was 3.7 months and 4.2 months respectively.
In support of this view, Burne and colleagues found the clinical outcome of alternative therapies inferior to that which is reported for cast immobilization.5 These authors found “limited evidence to support surgical intervention as a first line of management” and suggested that the large variance in different surgical approaches “may reflect a lack of consistently satisfactory outcomes.”
Reviewing The Findings From A Recent Meta-Analysis
A recent meta-analysis by Torg identified 313 tarsal navicular stress fractures in 23 reports in the peer-reviewed literature.7 Seventy of the 73 fracture patients (96 percent) initially treated with non-weightbearing cast immobilization for six weeks had a successful outcome with return to activity in an average of 4.9 months. Seventeen of the 22 patients (77 percent) treated with non-weightbearing cast immobilization for less than six weeks had a successful outcome with return to activity in an average of 3.7 months. Only 41 of the 92 (44.5 percent) patients initially treated with weightbearing rest and/or cast immobilization experienced a successful outcome with return to activity in an average of 5.7 months. Fifty-four of 66 patients (82 percent) with initial surgical treatment had a successful outcome with return to activity in an average of 5.2 months.
Comparing the modes of treatment, the authors found no statistically significant difference between non-weightbearing conservative treatment and surgical intervention.7 Patients treated with non-weightbearing conservative therapy experienced more successful outcomes (96 percent versus 44 percent) than patients treated with weightbearing conservative therapy. There was no statistically significant difference between non-weightbearing conservative management and surgical fixation regarding successful outcome or the time to return to activity.
Torg and colleagues further analyzed and compared the effectiveness of non-weightbearing treatment with surgical intervention as secondary treatment modalities following failed weightbearing management.7 Although this particular analysis had limited value because of the small numbers, there was no statistically significant difference between the treatment methods.
Case Study: Treating A Football Player Who Has Exacerbated Foot Pain When Making Cuts
A 16-year-old high football player received a referral to our office from his athletic trainer. The patient had pain in his left foot that had been present for three weeks but denied any trauma to the foot. The wide receiver said his pain was exacerbated when making cuts or coming out of his route.
Upon performing the physical examination, we noted no swelling or erythema over the dorsum of the foot. However, he did have point tenderness over the central aspect of the navicular. Hopping on the affected foot reproduced his pain.
Plain radiographs were unremarkable. We subsequently obtained a technetium labeled bone scan, which demonstrated increased uptake in the left midfoot. A MRI demonstrated a stress reaction within the central third of the left navicular.
The patient wore a short leg cast and was non-weightbearing for six weeks. After cast removal, the patient wore a walking boot for an additional two weeks. He resumed jogging eight weeks after the initiation of his treatment and was able to return to football later in the same season with complete resolution of his symptoms. The patient remained pain free at the most recent follow-up visit.
The recent literature suggests that patients with navicular stress fractures are undergoing surgery or they are receiving conservative weightbearing management as a first-line treatment option with the expectation that they will return to their activity more quickly.5,26,27 Although surgical treatment seems increasingly common, it remains largely underreported in the literature.
Patients treated with non-weightbearing cast immobilization for six weeks should expect a successful outcome in over 90 percent of cases and a return to activity in approximately five months.7 First-line surgical treatment resulted in successful outcomes in only 82 percent of cases. Conservative non-weightbearing management is the standard of care for initial treatment of both partial and complete stress fractures of the tarsal navicular.7 Conservative weightbearing treatment is never recommended for navicular fractures and surgical intervention is reserved for failed conservative treatment.
Dr. Fowler is a fourth-year resident within the Department of Orthopaedic Surgery and Sports Medicine at the Temple University School of Medicine in Philadelphia.
Dr. Gaughan is an Associate Professor of Physiology and the Director of the Biostatistics and Consulting Center at the Temple University School of Medicine in Philadelphia.
Dr. Boden is board certified in sports medicine and orthopedic surgery by the American Board of Orthopedic Surgery. He is in private practice in Rockville, Md.
Dr. Torg is an Adjunct Clinical Professor in the Department of Orthopaedic Surgery and Sports Medicine at the Temple University School of Medicine in Philadelphia. He is in private practice at the Orthopaedic Center in Rockville, Md.
For further reading, see “Key Insights For Treating Navicular Stress Fractures” in the October 2008 issue of Podiatry Today or “How To Detect And Treat Running Injuries” in the May 2005 issue.
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