Multiple Tibial Insufficiency Fractures in the Same Tibia

Abstract

Stress fractures were first described by Briethaupt in 1855. Since then, there have been many discussions in the literature concerning stress fractures, which have been described in both weight-bearing and non-weight-bearing bones. Currently, the tibia is the most frequent location, but multiple stress fractures in the same tibia are rare. This paper presents an unusual case of a 60-year-old woman with multiple tibial stress fractures of spontaneous onset.

Case Report

A 60-year-old woman was seen and followed at our department for right leg pain. The medical history of this woman included multiple depression episodes, resection of a benign left breast cancer tumor, morbus Parkinson, thyroid dysfunction after intake of lithium, and rib fractures after a fall. Her medication chart mentioned an antidepressant (imipramine), analgetics (paracetamol and tramadol), her Parkinson medication (prolopa and levodopa), and a sleeping tablet (lormetazepam).

Her initial symptoms of lower right leg pain with associated redness of the overlying skin were experienced since June 2005. She first consulted the department of neurology, where she was admitted for further investigation. An ultrasound was helpful to exclude deep-venous thrombosis. Radiographic images confirmed the absence of any osseous pathology. Empiric antibiotics (amoxicillin) for possible erysipelas were commenced, without any result. Evoked potentials as well as EMG were normal. Laboratory analyses showed slightly elevated LDH but normal CRP and sedimentation rates, normal calcium levels and alkaline phosphatise, and normal vitamin D and PTH levels. Kidney and liver functions were also within normal range. Discharge with NSAIDs and observation.

Fourteen days after discharge, the patient was readmitted with immense pain, inability to walk, mild swelling of her lower leg, and redness. Ultrasound showed some edema in the lower leg, while radiography revealed slight periosteal reaction on the dorsal side of the distal tibial metaphysis (Figure 1 ). Magnetic resonance imaging (MRI) confirmed the edema of the distal half of the tibia with concomitant inflammation of the surrounding soft tissue (arrow). Additionally, the MRI showed a fracture line in the distal tibia (arrowhead; Figure 2 ). All the above-mentioned signs and findings were in favor of a stress fracture (insufficiency fracture); however, infection or any malignant pathology still had to be ruled out. To complete the technical investigation, a bone scan was performed. Hyperemia of the middle and distal tibia suggestive of osseous pathology was found, no evidence of malignancy, however indicative for stress fracture versus osteomyelitis (Figures 3 and 4 ). The latter was ruled out by a leucocyte scan and renewal of laboratory analysis, which were normal and comparative to previous results. The diagnosis of insufficiency fracture at multiple sites of the same tibia was determined, despite no evidence of trauma or raised activity level of any kind. Treatment in the form of cast immobilization was started.

Figure 1.

X-ray of the right lower leg, showing slight periosteal reaction of the distal tibial metaphysis (arrow).

Figure 2.

Magnetic resonance imaging of the right lower leg revealed edema of the distal half of the tibia with concomitant inflammation of the surrounding soft tissue (arrow). In addition, a black line was noticed, suggestive of an insufficiency fracture (arrowhead).

Figure 3 and 4.

Bone scan revealed the hyperemia of the distal tibia, suggestive of osseous pathology.

A second opinion was obtained from a colleague specializing in orthopedic tumor pathology. Our tentative diagnosis of multiple insufficiency fractures of the lower part of the tibia was confirmed. This involved little fissure lines of at least 5 areas on the tibia on a detailed thin cut MRI. Radiologically, there was no evidence of malignancy.

Non-weight-bearing cast immobilization was advocated for 6 weeks, followed by partial weight bearing for 6 weeks. Further investigation by a colleague specializing in metabolic diseases did not reveal any underlying pathology that could explain why this patient suffered from these insufficiency fractures. A dual energy x-ray absorptiometry (DEXA) scan did not reveal osteopenia or osteoporosis. Nevertheless, monthly pamidronate therapy was started to prevent osteoporosis and development of new fractures. After 2 months, the continuation of this treatment was refused by the patient.

Control of the lesion with MRI and a bone scan confirmed the progressive healing of the lesion, although very slowly. Healing occurred at 1 year after diagnosis and commencement of the treatment. The patient returned to normal daily activities. An excellent functional outcome was achieved.

Discussion

Stress fractures were first described by Briethaupt in 1855.¹ He described fractures involving the metatarsals in Prussian soldiers and coined the term “march” or “Deutchlander’s” fractures. Since then, there have been many discussions in the literature concerning stress fractures, which have been described in both weight-bearing and non-weight-bearing bones.^1–4 From an etiologic point of view, 2 types of stress fractures can be differentiated: fatigue fractures and insufficiency fractures.^2,5 A fatigue fracture is caused by the application of abnormal muscular stress or torque to a bone that has normal elastic resistance. However, one can suffer from an insufficiency fracture, which occurs when normal or physiologic muscular activity stresses a bone that is deficient in mineral or elastic resistance.²

The main site of insufficiency fractures is the pelvic ring, but they can occur in all bones of the lower limbs.⁵ The tibia is a common location for stress fractures, most likely due to overload, such as in runners. In the tibia, the fractures are most commonly seen in the posteromedial cortex of the upper or lower third. Stress fractures of the midanterior cortex are much less frequent.⁶ Multiple stress fractures in the same bone are an extremely rare condition. Until now, there has only been 1 article published by Aryoshi et al who described a similar case.⁶

The precise pathogenesis for these spontaneous fractures is different whether we deal with fatigue fractures or insufficiency fractures. Fatigue fractures result from a variety of activities, and so the site of occurrence is activity-related.² Otherwise, insufficiency fractures occur in a variety of conditions, in which the mineral content or the elasticity of bone is abnormal.² Stress, related to daily activities, stimulates the remodeling process. Increased osteoclastic resorption is the initial response to abnormal stress. If the increased stress persists, imbalance between bone resorption and bone replacement leads to weakening of the bone. Weight bearing, muscle actions, and muscle fatigue play a role in increasing stress on bone. In the tibia, tensile forces are produced along its anterior convex cortex, while compressive forces occur along its posterior concave margin.⁷ Accelerated intracortical remodeling causes microscopic cracks, osteopenia, and formation of resorption cavities, which may develop into larger lesions. Stresses in cancellous bone may initially result in microfractures. If the stimulating activity is not decreased, the accumulation of microdamages may result in a stress fracture of cortical or trabecular bone.^2,8 From an architectural point of view, all these materials behave according to Wolff’s law.^2,9

The diagnosis of stress fracture is frequently based on clinical findings of focal tenderness and pain, mostly with a history of change in baseline activity or training. Pain is associated with a particular activity. The pain is relieved by rest and becomes worse when the activity is continued.² In cases of associated medical conditions, such as osteoporosis, rheumatoid arthritis, osteomalacia, diabetes mellitus, fibrous dysplasia, Paget disease, and some other less frequently occurring pathologies, one may consider an insufficiency fracture.² We encountered 3 large series in the literature that described the evolution of the fracture as well as its clinical presentation. In 1990, Satku et al reviewed 16 cases involving 18 fractures, observed over 4 years.¹⁰ In 1996, Lassoued and Billey reported 9 fractures in 8 patients seen in 1 year.¹¹ In 2006, Ruohola et al reviewed 154 military patients for stress-related anterior lower leg pain.¹² To confirm a clinical suspicion, technical investigation should be performed. Diagnostic delay is often due to delayed appearance of radiographic changes and can range from 15 days to 18 months.^13,14 In the early stages, radiographs are often normal. But with continued stress, periosteal reaction and cortical thickening develop at the site of injury, which makes the fracture visible on a standard radiograph over time.^1,13,15 A 3-phase technetium 99m bone scan is a useful technique for diagnosis. This technique is sensitive to diagnose osseous pathology at an early stage. A positive scan shows fusiform or focal uptake at the symptomatic site.¹ However, the bone scan lacks specificity for clear and strict diagnosis. Magnetic resonance imaging, on the other hand, might be slightly more specific and suggested by some to be the modality of choice; however, MRI can falsely suggest a tumor. Both investigations, MRI and technetium 99m bone scan, still lack sensitivity and specificity to diagnose early stress fractures. Therefore, they should be used complementarily. New, more detailed MRI investigations have more specificity to evaluate smaller lesions.

Differential diagnosis should include periostitis, medial tibial stress syndrome, tibial stress reaction, anterior compartment syndrome, or fascial hernia.¹ Infection and tumors, such as osteogenic sarcoma, Ewing’s sarcoma, and osteoid osteoma, as well as metastasis, should also be considered.^1,2 To differentiate, radiographs, bone scanning, and MRI are necessary.

Treatment consists primarily of rest, activity modification (when related to overuse injuries), and cast immobilization for 6 to 12 weeks.^1,16 Midanterior tibial stress fractures are particularly difficult to treat and frequently require a long period of closed treatment.¹ Surgery with intramedullary nailing may be considered in some persistent or recurrent cases.^1,16 However, most cases of stress fractures that do not involve complete cortical disruption will resolve in 6 to 20 weeks.¹ Osteoporosis should be ruled out by a DEXA scan, which measures bone mineral density. When present, it is necessary to treat this condition to prevent future hip or vertebral compression fractures. Osteoporosis was not present in this case, which made it so particular. So the exact cause of these multiple insufficiency fractures remains unclear.