Outcome of surgical and conservative treatment therapies for stress fractures of the anterior tibial cortex

L.A. Fruytier1 M.P. Heijboer1 T.M. Piscaer1

1 Department of Orthopaedic Surgery, Erasmus University Medical Centre, Rotterdam, The Netherlands

Corresponding author: L.A. Fruytier, L.fruytier@erasmusmc.nl


Aim: to define the outcomes of the different treatment strategies for stress fractures of the anterior tibial cortex. Background: stress fractures of the anterior tibial cortex are known as high-risk stress fractures. These fractures are sometimes hard to recognize, heal slowly and have a high recurrence rate. Different treatment strategies have previously been described, but there is no consensus on which is the best procedure.

Methods: we retrospectively analysed the outcome of stress fractures of the anterior tibial cortex that were treated in the Erasmus MC, Rotterdam, The Netherlands between 1985 and 2015. All patients with a diagnosed stress fracture of the anterior tibial cortex were included. The treatment consisted of surgical or conservative treatment. Questionnaires were sent to all patients to research medical history, sports activities, results of treatment therapies, the time to return to sport and the level of activity. All available X-rays were analysed and compared with the clinical results.

Results: eight men and thirteen women were included (mean age was 38 years) of which five patients had bilateral fractures. All patients were participating in sports, thirteen were elite athletes. Sixteen patients underwent surgery. The satisfaction score after surgery was mainly good (67%) or excellent (17%). Five patients treated by surgery reported a mean recovery time of 8,4 months (range 3-18 months, SD 11.0). Four patients had a secondary operation to remove a locking screw or the intramedullary nail. The satisfaction in de group with conservative treatment was evaluated in 78% as poor or moderate. Eight of the seventeen X-rays showed an improved radiologic score (47,1%) after treatment, nine fractures were unchanged (52,9%). Clinical improvement correlated well with the radiological improvement. The Tegner score before injury was 8 in the surgical treated group (range 4-10, SD 2.2) and this was comparable to the score after treatment (range 3-10, SD 2.7). The Tegner score of the conservatively treated group was 10 before injury and 8 after treatment (range 6-10, SD 2.0).

Conclusion: we found good results for surgical treatment with intramedullary tibial nailing for patients with a stress fracture of the anterior tibial cortex.

METC: MEC-2015-388

Background Stress fractures are common overuse injuries in athletes.1 They have been described in nearly every bone, but they are more common in the weight-bearing bones of the lower extremities. Stress fractures can be classified in low- and high-risk fractures.2 Low-risk stress fractures are predictable and respond well to conservative treatment. High-risk stress fractures are hard to recognize, heal slowly and have a high recurrence rate. Surgical treatment in this type of fracture is necessary more often. Stress fractures of the anterior tibial cortex are known as high-risk stress fractures.1,2 They differ in clinical behaviour from the more common and easier to treat posteromedial tibial stress fractures.3 Other locations of high-risk stress fractures of the lower leg are the navicular bone and the proximal fifth metatarsal.3,4 Of all tibial stress fractures, 5% is located in the anterior mid-third of the diaphysis.5 This particular location on the anterior side of the tibia was first described by Burrows in 1956.6 He reported cases of similar mid-tibia defects in four young, healthy ballet dancers. Anterior tibial stress fractures are sometimes hard to recognize, and this can result in a delay in a definitive diagnosis and initiation of treatment. There is a high rate of non-union and there is also a risk of a complete tibial fracture.7 In some cases, patients have (multiple) stress fractures in both tibias. These injuries are mainly seen in (high-level) athletes. They often occur due to repetitive loading and high-impact forces applied during sports, but this is not always clear. Also recreational athletes and patients with osteopetrosis, other bone diseases or unknown causes are diagnosed with these kind of stress fractures.2 Therefore, in the diagnostic process the difference with an insufficiency fracture is not always easy.8

Bone tissue is dynamic, and it adapts to the stresses placed on it by remodeling.9 Due to excessive, repetitive, submaximal loads on bones, an imbalance between bone resorption and formation can be developed and local tissue damage may occur. Multiple factors are important: these include the bone composition, vascular supply, surrounding muscle attachment, systemic factors and type of athletic activity.2 Stress fractures of the anterior tibial cortex are mainly seen in sports with a lot of running and leaping. In the literature long distance running, athletics, basketball, volleyball, ballet, and artistic gymnastics have been particularly mentioned.2,4,10 Patients usually present with anterior tibial pain during activity, localized pain, and sometimes also a palpable and warm swelling at the fracture site. The healing time can be very long and this can result in a long absence from sports activities.4 Plain X-rays show an unicortical fracture line with a thickened anterior tibial cortex and regularly, a narrow medullary canal.11 Different strategies have previously been described, but there is no consensus on which is the best treatment.1,10 Often the therapy starts with conservative treatment such as rest, bracing, physiotherapy, electrostimulation or extracorporeal shock wave therapy.4,12 When the results are unsatisfactory, surgical treatment with an anterior tibial tension band plate or an intramedullary tibial nail may lead to healing of the fracture.13 The result of the conservative treatment varied. A small case study of Batt et al. showed symptom free results in four cases after a mean of twelve months.14 Johansson et al. showed disappointing results at follow-up after 24-60 months after the initial symptoms.15 In some case series there is evidence for a good result with surgical treatment.16,17,18,19 Considering that these are only small case series, the level of evidence is low. Both intrinsic and extrinsic factors may predict the risk for stress fractures.20 Compared to posterior tibial cortex stress fractures, stress fractures of the anterior tibia cortex differ in prognosis, treatment, and healing time. Several studies about the biomechanical influence on stress fractures of the tibia have been conducted. The development of an anterior tibial stress fracture is in most articles described as a result of tension forces.10,21 The anterior side of the tibia is considered as the distraction side and the posterior side as the compression side, which is said to be secondary to the action of the calf muscles.

Different treatment strategies have previously been described, but there is no consensus on which is the best procedure. Aim of our retrospective study is to give more insight into the outcome of different treatment therapies for stress fractures of the anterior tibial cortex. We hypothesize that intramedullary nailing is a good treatment for patients with this injury.

Methods

Population/patients We retrospectively analysed patients with stress fractures of the anterior tibial cortex. All patients were seen or treated in the Erasmus MC, academic medical centre, Rotterdam between January 1985, and July 2015. All patients who had a diagnosed stress fracture of the anterior tibial cortex were included (figure 1). Patients diagnosed with metabolic bone disorders were excluded. Permission from the Dutch Medical Ethics Review Committee (METC) was requested and allocated (nr. MEC-2015-388).

Figure 1. Typical radiological image of a stress fracture of the anterior tibia. A fracture line with anterior cortex thickening, a narrow medullary canal and a periosteal bridge is seen.

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Outcome measures We analysed the outcome of different treatment therapies in our cohort, both conservative and surgical. Endpoints are activity levels before and after treatment, complications, satisfaction, and the time to return to sport. Radiographic results were also analysed. Outcomes of surgical and conservative treatment were compared. Clinical outcomes were also compared with the radiological results. Questionnaires Questionnaires were sent to the included patients. All patients received an informative letter, a letter of informed consent and the questionnaire. The questionnaires consisted of the following parts: medical history, sports and (results of) treatment therapies. Patients reported their satisfaction as a score from 1 to 10, with 10 as the highest level of satisfaction. The scores are classified in four groups: poor (1-3), moderate (4-6), good (7-8) and excellent (9-10). It also included a pre- and post-Tegner score, which gave an indication about the patient’s activity level on a scale from 0 to 10.22 Patients who underwent surgery were asked about the length of recovery after surgery and about complications.

X-rays All lateral tibial X-rays were reported on by two persons and the development over time was evaluated. The applied classification is based on the Torg Classification.23 This classification was originally developed to evaluate fractures of the proximal fifth metatarsal and consists of Type I, Type II and Type III. These types differ in radiographic appearance and thereby in de degree of union. In the absence of a standardized radiologic grading for anterior tibial cortex stress fractures, we made a classification based on the Torg Classification (table 1).

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Results Population/Patients There were 21 patients with 26 stress fractures of the anterior tibial cortex. The mean age of the patients was 38 years (range 21 to 65) at the time of the questionnaire. Nine patients had one or more stress fractures of the left tibia, seven of the right tibia and five patients had bilateral fractures (table 2). Thirteen patients were elite athletes, participating at international level.

Questionnaires and database Fifteen patients responded to the questionnaires (71%). These patients were treated for their anterior tibial stress fracture(s) between 1993 and 2014. Three of them had bilateral stress fractures. Treatment Sixteen patients underwent surgery (table 2). One of them had an excision of the fracture site and one spongioplasty with bone from the iliac crest. Fourteen patients received an intramedullary nail (66,7%), three of them also had a local bone excision at the stress fracture site. Four patients had an intramedullary tibial nail in both legs. Five patients received conservative treatment with rest, physiotherapy and/or electrostimulation. During surgery with intramedullary nailing a reamed T2 tibial nail was used. Nine surgeries were performed with using one proximal locking screw. Three surgeries were done without any locking screw and one with two proximal screws. One surgery was also performed with both a proximal and distal locking screw. Satisfaction Of patients treated by intramedullary nailing, both with and without excision, the majority evaluate this with a good (67%) or excellent (17%) score (table 3). Conservative treatment therapies were mostly evaluated as poor or moderate (78%). Overall, 57% of all patients reported their treatment as good or excellent. The average score of satisfaction from the operative group was 7,4 (range 3-9), and 4,4 (range 1-10) in the non-operative group.

Table 3. Satisfaction on different treatment therapies.

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Recovery time Five patients who underwent treatment with a tibial nail reported the time returning to sports from three to eighteen months (mean 8,4 months, SD 11.0). The only patient with spongioplasty reported eighteen months to return to sport. Two patients never returned to their former sports. Complications Ten patients with surgery for an intramedullary nail answered the question about complications. Nine people reported no complications after surgery. One patient reported a complication with the anaesthesia and had some nerve damage after surgery, which wasn’t further specified. Three patients reported anterior knee pain as a long-term post-op complication and in one patient pain was the reason to remove the intramedullary nail after a few months. Three symptomatic locking screws were also removed. Tegner score In the surgical treated group, the mean Tegner score before injury was 8 (range 4-10, SD 2,2), this is exactly comparable with the score after injury (range 3-10, SD 2,7). One patient had a higher post-Tegner score than pre-Tegner score. Two patients scored one point lower than before injury. All other patients returned to the same level of activity after their treatment. The Tegner score of the conservatively treated group was 10 before injury and 8 after treatment (range 6-10, SD 2.0).

Radiological results Seventeen patients’ X-rays were available (table 4). Five patients had bilateral images. Of the twenty-two lower leg images, five stress fractures had just an image at the baseline. All reported X-rays were before and after surgery. Based on the remaining seventeen X-rays nine fractures seemed to be unchanged (stable) (52,9%) and eight fractures had an improved score (47,1%). None of the stress fractures seemed to worsen over time. In eight images (47,1%) more than one fracture line was noticed at different levels of the tibial diaphysis (figure 2). The time between the initial image and the post-surgical image varies from 4-41 months.

Table 4. Results of the treatment based on radiological outcomes.

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Figure 2. A tibia that shows fracture lines at different levels of the anterior cortex.

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Radiological versus clinical results We don’t have both radiological and clinical results from all the patients. In patients with both results, the clinical outcomes were in accordance with the radiologic results (figure 3 and 4). All patients with improved X-rays showed an evident better clinical outcome.

Figure 3. Radiograph of the lower leg of a professional volleyball player right after surgery in May 2011 with an evident stress fracture of the anterior tibia cortex.

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Figure 4. Improved radiograph of the same volleyball player in May 2015, with also a good clinical result.

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Discussion In our retrospective cohort, surgical treatment with an intramedullary nail showed good results for the treatment of stress fractures of the anterior tibial cortex. Although this is a retrospective study, it gives some more information about stress fractures of the anterior tibial cortex. With 26 stress fractures this is the largest cohort on this subject so far. The results are comparable with the literature, which usually consist of small case series about these stress fractures. However, most patients will only undergo surgery when conservative treatment did not have a sufficient effect. Patients with satisfying conservative treatment are usually not referred to a (university) hospital. This could be a source of selection bias. In our cohort there were also patients who had conservative treatment therapies before they were diagnosed and treated in the hospital. There was a large variability in the type and duration of the conservative treatment. The patients in our cohort were treated between 1993 and 2015. This extensive period of time led to new insights during the years. A local bone excision at the stress fracture site was performed in some of the first surgical treated athletes in this cohort. More experience with intramedullary tibial nailing, for example for tibial shaft fractures, and new insights in the biomechanical effects of the tibial nail changed the medical approach. An additional local bone excision is not essential for the healing of a stress fracture.

A remarkable fact is that eight people showed more than one fracture line on the X-rays, at different levels. This suggests that the diaphyseal bone of the tibia is part of the pathological process and not able to withstand mechanical forces. Therefore, for biomechanical reasons, the tibial nail might be a better solution compared to a tension band plate to treat these stress fractures. The intramedullary tibial nail reduces the bending and compression forces on the diaphysis. A tension band plate will probably contribute to the healing of the stress fracture but may produce a stress riser at the plate-bone transitional area. However, as this surgery wasn’t performed in our patients a conclusion on this specific treatment therapy can’t be made based on this study. Chang et al. and Varner et al. also showed good results for intramedullary nailing of the tibia in their cohorts .11,18

In Brukner & Khan’s Clinical Sports Medicine, surgery is suggested when there is an inadequate result after four to six months of conservative therapy.24 An advised conservative method is the use of a pneumatic lower leg brace. A small case report described four cases with a successful outcome.14 Although the mean time for returning to sport was twelve months. We do not have exact data about the diagnostic delay in this cohort. Several patients suggested a long delay time though between the start of their complaints and the (final) treatment, with sometimes more than one or two years before the right diagnosis could be determined. Another shortcoming in this study is that there were no complete results about the exact time for returning to sports. In the systematic review of Robertson et al, the mean time after intramedullary nailing was 6 months, in our study 8.4 months.10

Thirteen of the twenty-one patients were elite athletes (62%). In high-level athletes, development of stress fractures seems to be quite easy to understand due to the heavy load the tibia is exposed to. Although eight of the twenty-one patients were not high-level athletes (38%). In these athletes there can be several reasons for developing a high-risk stress fracture. A higher training load without the time for adaptation, change of activities or variation in body weight and composition could develop stress fractures. It is shown that athletes with stress fractures have lower bone mineral densities than well-matched control athletes without symptoms.25 Also, lower dietary calcium intake and menstrual factors are shown to be reasons for stress fractures. The definition of a stress fracture implies that it occurs in normal bone. In the case of a stress fracture, the exposed load is increased or changed. During the response of bone turnover, the production of new bone cannot keep pace with resorption. However, if bone quality is abnormal the better definition might be an insufficiency fracture. In this study, there were possibly a few examples of such an insufficiency fracture. Since not all cases can be explained by high, repetitive forces, more research for other causes is recommended. Conclusion In our retrospective cohort intramedullary tibial nailing proves to be a good treatment for stress fractures of the anterior tibial cortex. This treatment has to be highly considered when conservative treatment does not help. For elite-level athletes reamed intramedullary nailing seems to give a more predictable result compared to conservative treatment, because of faster healing, a lower recurrence rate and a lowered risk of a complete fracture. Disclosure statement None of the authors have anything to disclose.

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