Abstract
Background:
Navicular stress fractures of the foot often are difficult to diagnose and treat.
Methods:
Nineteen athletic patients seen from 1999 to 2003, were compared to a previously treated group of 22 athletes with similar injuries treated from 1994 to 1998. Based on the frontal plane CT images, a previously described classification system was used to assess the injury: type I dorsal cortical break; type II fracture extending into the navicular body; and type III fracture breaches two cortices. Nonoperative treatment was recommended for patients with type I injuries and open reduction and internal fixation (ORIF) were recommended for those with type II and III injuries. The time to return to activity and ability to return to competition were assessed, along with differences between fracture type and gender.
Results:
Return to activity (RTA) was 4.0 months for the entire group. RTA for type I (four injuries), type II (eight injuries), and type III (seven injuries) was 3.8, 3.7, and 4.2 months, respectively. Fifteen of 16 competitive athletes returned to full competition, including all who had ORIF.
Conclusions:
Navicular stress fractures can take 4 months to heal with nonoperative or operative treatment. Surgery should be considered for more severe injuries, which can be assessed by CT scan.
INTRODUCTION
Tarsal navicular stress fractures often are difficult to diagnose 2,7,9,13,14 and can cause significant disability, particularly in athletic individuals. Left untreated, they can result in complete fracture and arthrosis. 7 –9 Delayed union is common. 1,3,4,7 –9,12,13 A high index of suspicion is necessary when evaluating an athlete with midfoot pain. 7 –9,13 Symptoms often are caused by the navicular stress fracture localized to the “N-spot” or high-point of the navicular. 4,9 Pain and throbbing may be increased with activity that requires the athlete to sprint, but swelling may be minimal. 7 Plain films usually are negative. 5,7,9,11 Bone scintography is positive for uptake in the region of the navicular. 7,9,11 There is debate as to whether MRI is as helpful as CT, 7,9,11 with some authors suggesting that CT shows the definitive fracture pattern better. 5,7,9
In a previous study, Saxena et al. 9 proposed a radiographic (CT) classification system to guide treatment and possibly predict healing time. They found that the more severe the stress fracture (complete or incomplete fractures), the longer the healing time. They also suggested that surgery may be helpful for more severe injuries, particularly fractures showing cystic changes, sclerosis, and osteonecrosis. We wanted to verify this prospectively and compare the results, including the ability to return to sports, in a group of patients treated according to this protocol to a group of previously treated patients.
MATERIALS AND METHODS
A prospective study was conducted from 1999 to 2003, to study the healing times and results of treatment of stress fractures of the tarsal navicular in athletically active patients. Informed consent and institutional review board approval were obtained. The inclusion criterion was the ability to obtain the following data: age at the time of injury, sport, gender, injured limb, time to diagnosis, treatment (operative or nonoperative), return to activity, ability to return to competition, when indicated, and the lack of ability to return to the desired activity level. One patient with an incomplete fracture with sclerosis was excluded, because she refused to limit her activities and accept treatment. Another elite athlete was excluded, because even though she returned to full competition, her exact treatment regimen was unknown, and plain radiographs at the time of injury were unavailable.
Plain radiographs were obtained of each patient. A weightbearing lateral view was used to determine foot type. As classified by LeDoux et al., 6 a plantarly positioned first metatarsal axis in respect to the talar axis (lateral talar metatarsal angle) is indicative of a cavus foot; when both axes are in line (thereby a zero degree relationship), the foot is rectus, and if the first metatarsal axis is dorsal to the talar axis, the foot is classified as planus. In addition, all patients had a CT to confirm the diagnosis, using 1.5-mm sections. The injuries were classified by their frontal plane CT images: 9 type I: fracture invades only the dorsal navicular cortex (Figure 1); type II: fracture propagates into the navicular body (Figure 2); type III: fracture extends to a second cortex of the navicular. (Figure 3).
Nineteen patients fulfilled the inclusion criterion. The 11 women and eight men had an average age of 24.7 ± 9.2 years. Nonoperative treatment was recommended for type I injuries and operative treatment for types II and III injuries. The treatment regimen was chosen by the patient, precluding randomization.
Frontal image CT of type I injury.
Type II navicular stress fracture.
Type III navicular stress fracture.
Nonoperative treatment of navicular stress fractures consisted of 6 weeks of nonweightbearing in a below-knee cast boot, and then gradual weightbearing in the boot for 2 to 6 weeks until the patient was pain free. Patients were allowed to exercise on a stationary bike immediately with the boot on and to run into the deep end of a pool by 6 weeks. Lower extremity strengthening was initiated. Return to activity was allowed when the patient had no symptoms with daily activity and was able to walk briskly for more than 30 minutes.
Operative treatment consisted of open reduction and internal fixation. Postoperatively, patients were kept non-weightbearing in a below-knee cast or boot for 6 weeks and then weightbearing was allowed in a boot for another 2 to 6 weeks until the patient was pain free. Physical therapy was then initiated. Healing was determined on radiographs and when clinical symptoms abated. 4
The comparison group was a cohort of patients who were treated by the authors from 1994 to 1998, from whom similar data were obtainable retrospectively. Twenty-two injuries were compared to the study group. Followup information was gathered from both groups by direct evaluation and telephone interview.
Statistical analysis was performed, with a p-value set at 0.05. The Student's t-test was used to compare age and return to activity between the two groups, and within the study group return to activity was compared between the patients with different treatments (operative or nonoperative), and type of injury. The Stat-Sak statistical program (Malden, MA) and Microsoft Excel (Seattle, WA) were used.
RESULTS
In the study group, the foot-type consisted of three rectus, eight planus, and eight cavus feet. The average duration of symptoms before presentation was 2.7 months (range 0.5 to 240 months). The most frequent initial diagnosis was tendinitis (eight patients) (Figure 4). Except for the one patient who had symptoms for 20 years, the average time to reach a diagnosis was 5.8 ± 5.6 months (for type I, 1.1 month; for type II, 5.9 months; and for type III, 9 months) (Table 1). It did not appear that a traumatic event initiated symptoms in most patients, although some patients’ symptoms were immediate and acute. All but three patients had 2 or more years of followup. These three patients had more than 1-year followup and all had returned to sports including competition.
There were four type I, eight type II, and seven type III injuries. No statistical differences in outcome were related to age, type of fracture, treatment (nonoperative or operative), or gender. None of the patients with type I injuries had open reduction and internal fixation (ORIF) and all but two patients (one each with types II and III injuries) had ORIF (13 injuries). Four patients (three who had ORIF) had been treated nonoperatively for similar injuries 5 or more years earlier.
The average return to activity in the study group of 19 patients as a whole was 4.0 months ±1.3 months. Longer return to activity was correlated with the time to diagnosis (r ± 0.4). The delay in diagnosis appeared to be associated with more advanced radiographic findings. The return to activity for type I injuries was 3.8 ± 1.7 months, 3.7 ± 0.8 months for type II injuries, and 4.2 ± .08 for type III injuries. Four patients with type III injuries had ORIF with two screws. The return to activity of the 13 who had ORIF was 4.1 ± 1.2 compared to 3.7 ± 1.6 months for the six with nonoperative treatment, the return to activity in women was 3.75 ± 1.4 compared to 4.2 ± 1.2 months in men.
Fifteen of 16 competitive athletes were able to return to full competition. The one patient who did not was one of two patients who had a decreased activity level. She did not return to activity for 7 months and was one of two patients with type II or III injuries who elected not to have surgery. The other patient with a decreased activity level was a recreational runner who had sustained his injury 4 years earlier and had signs of osteonecrosis on radiographic studies.
None of the patients sustained a refracture, and there were no nonunions. Nine patients in the ORIF group had autogenous bone grafts, because they had delayed unions at presentation. Five patients did not require bone grafting because their fractures were less than 3 months old. One of the patients who had ORIF required screw removal. Another patient exhibited signs of arthrosis at 4-year followup radiographs. Six patients used external bone stimulation, with a pulsed electronic magnetic field (PEMF) device. This was used when the patients’ insurance allowed it for delayed union (five). The return to activity of patients using PEMF compared to no PEMF was the same (4.0 ± 1.1 and 4.0 ± 1.4 months, respectively).
Our previously treated comparison group consisted of 19 patients who had 22 injuries (three bilateral injuries occurring at separate times). The mean age of this cohort was 27.2 ± 10.2 years. There were 10 women and nine men. There were 13 type I injuries, 5 type II, and 4 type III. Nine injuries (4 type I, three type II, and two type III) were treated with ORIF and 13 were treated nonoperatively. The return to activity for type I, type II, and type III were 3.0 ± 1.2, 3.6 ± 0.9, and 6.8 ± 4.2 months, respectively. Two patients who were competitive athletes were unable to return to competition after nonoperative treatment.
The combined information of both cohorts yields data on 41 navicular stress fractures, with average patient age of 25.9 ± 9.7 years. The mean return to activity was 3.9 ± 1.9 months. In combination, 23 had ORIF and 18 were treated nonoperatively. The difference in return to activity between patients treated with ORIF and those treated nonoperatively was 3.65 ± 2.5 months, which was not statistically significant (p = 0.33). There were no refractures, nonunions, or complications from surgery.
DISCUSSION
Our study confirms the findings of an earlier study of 22 navicular stress fractures 9 that the more involved the fracture, in general, the longer the healing time. However, the difference may be minimal according to our findings. The shorter return to activity times for types II and III injuries in our study compared to that reported in previous studies indicates that surgery is a worthwhile consideration. Two of our patients with type II injuries who did not have ORIF took an average of 6 months to return to activity times, and one no longer competes. Our combined data on 41 injuries confirms that navicular stress fractures typically take approximately 4 months to heal.
Data on 19 navicular stress fractures
Fracture type: fracture pattern on frontal CT image; RTA: return to activity in months; ORIF: open reduction internal fixation; bone stimulation: external pulsed electronic bone stimulation; months to diagnosis: number of months until injury correctly diagnosed.
Other authors 5,7,12 –14 have shown that delayed union of navicular stress fractures is not uncommon; however, they did not specify the severity of the fractures. In the series of Khan et al., 4 patients treated nonoperatively took 5.6 months to heal, while those who had ORIF took 3.8 months. Some authors recommend nonoperative initial treatment of navicular stress fractures, 5,12 while others recommend strong consideration of operative treatment because of the frequency of delayed union and unpredictable healing time. 3,9
Delays in diagnosis can be a concern in athletes; Lee and Anderson 7 reported advising athletes with navicular stress fractures that a season will be lost. In one of our patients, misdiagnosis led to arthrosis and a limited activity level. It is difficult to say how much effect misdiagnosis has on healing, but it is likely that continued activity may cause further propagation of fractures, malunion, and arthrosis. Foot-type also did not seem to be a factor in severity of injury or outcome.
Athletic patients often have a high pain threshold and may only exhibit pain during or after activities that require them to be on their toes. Because navicular injuries often have little clinical symptomatology, such as edema and ecchymosis, the “N-spot” should be palpated for tenderness (the high point of the navicular at its proximal articulation with the talus) and the patient asked about pain with sprinting activities. 4,7,9
Delay in diagnosis of navicular stress fractures may be attributed to the lack of consistent radiology protocols. Plain radiographs often are negative. 2,7,9,11 CT generally is considered the “gold standard.” 5,7,9 MRI shows the marrow edema on T2 images, but the fracture pattern may be difficult to discern, and small ossicles often are noted with these injuries. 5,7,9 Furthermore, it is difficult to differentiate between stress fracture and osteonecrosis on MRI. 7 Because of this, CT imaging (with 1.5-mm sections) to evaluate fracture location and type is wise.
Larger series of navicular stress fractures may show differences in outcomes of operative and nonoperative treatment for the various types of injury. Based on our findings, and the data previously published by others which show a high occurrence of delayed union, 1,3,7,9 serious consideration should be given to early operative treatment. Additional “down-time” if nonoperative treatment fails may not be acceptable to athletic patients. Because no refractures or delayed unions occurred in our patients with ORIF, it appears that immediate operative intervention could be considered for types II and III injuries; nonoperative treatment is acceptable for type I fractures.
The limitations of the study include the inability to conduct a randomized, placebo-controlled, double-blind study. Because most of our study patients were competitive athletes, this could not be done. None of the other series published to date have conducted such a study. No previous study has shown a correlation between fracture severity and length of healing time. Larger prospective series are needed to verify the validity of the CT classification system as to healing times and ideal treatment.