Rheumatology Advance Access originally published online on April 12, 2005
Rheumatology 2005 44(7):949-950; doi:10.1093/rheumatology/keh634
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LETTER TO THE EDITOR |
Insufficiency fracture of the tarsal navicular in a patient with rheumatoid arthritis
Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Japan
Correspondence to: Y. Kageyama, Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Japan. E-mail: Tsukatonpipi{at}nifty.com
SIR, Insufficiency fracture is one type of stress fracture that occurs in weakened bone, as described by Pentecost et al. [1], and are sometimes seen in patients with rheumatoid arthritis (RA). Until recently, no report of insufficiency fractures in the tarsal navicular in patients with RA had been found, while several reports of fatigue fractures in the tarsal navicular in athletes have been published [2–4]. We describe a rare case of an insufficiency fracture occurring in the tarsal navicular of a patient with RA.
In December 2002, a 69-yr-old woman with RA, who had been visiting our hospital, complained of left midfoot pain. She had no history of any acute trauma, and the pain increased when she stood and walked. She had suffered from RA for 31 yr, and at the time of the occurrence of the foot pain she was receiving 1000 mg/day of sulphasalazine and 5 mg/day of prednisolone. C-reactive protein in serum was 4.5 mg/dl, rheumatoid factor 205 IU/ml, Ca 4.3 mg/dl, and inorganic phosphorus 3.7 mg/dl. Her bone mineral density in lumbar spine 2–4, which we had measured in 2001 by dual-energy X-ray absorptiometry (Lunar DPX-MD densitometer), had shown significant osteopenia (bone mineral density 0.733 mg/cm2, T-score: 1.192 ± 3.1SD, Z-score: 0.913 ± SD).
The patient had undergone a forefoot operation for a deformity of metatarsophalangeal (MTP) joint involvement due to RA in 2000. The first MTP joint had been fixed, and MTP joints 2–5 were resected as previously described by Clayton [5]. Upon examination, tenderness of the foot was found over the tarsal navicular body. Ecchymosis, swelling and deformity were not noted. In a standing position, the arch height of the foot was slightly decreased, and the medial side of the tarsal navicular touched the floor.
The plain X-ray revealed an undisplaced vertical line of the fractures at the medial side of the tarsal navicular body (Fig. 1).
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The patient's history of navicular fracture of the tarsal navicular did not have an acute traumatic aetiology. Therefore, repeated stress to the medial side of the tarsal navicular, which touched the floor directly, was considered to have caused the tarsal navicular fracture. In addition, the onset of the insufficiency fracture of the tarsal navicular was diagnosed from a low bone density of the foot by plain X-ray. To treat the insufficiency fracture, the patient was placed in a non-weight-bearing cast for 4 weeks as the start of treatment. After that, the patient was fitted with a plantar leather orthosis to improve midfoot support. About 2 months later, the symptoms were resolved and a plain X-ray showed bone union of the tarsal navicular fracture.
Stress fractures occur as a result of repeated load on the bone [1]. Stress fractures are divided into two groups: fatigue fractures, which occur in normal bones by abnormal stress, and insufficiency fractures, which occur in weak bones with diminished elasticity, including those with osteoporosis. Towne et al. first described tarsal navicular stress fractures in humans in 1970 [6]. Since then, many investigators have provided several reports of tarsal navicular stress fractures [2–4, 7]. However, these reports are of groups composed mostly of athletes who had suffered fatigue fractures of the tarsal navicular. In addition, no reports of insufficiency fractures in the tarsal navicular in patients with RA have been found in the literature.
The mechanism by which stress fractures occur in a tarsal navicular has been described previously [8, 9]. As the hind foot progresses from eversion to inversion during heel strike to toe-off, the navicular slides 5–10° horizontally medial to the talar head. In the frontal plane, it turns and overlaps the talus by approximately 25°.
Biomechanical analysis of navicular motion during the gait cycle reveals most of the force at the central third of the navicular bone. In our patient, the fracture occurred in a more medial part, but not at the central third of the tarsal navicular. Stress fractures of the tarsal navicular in athletes generally occur due to impingement stress between talus and cuneiform bone. Also, the fractures often occur at the central third of the tarsal navicular; this part of it is an avascular area [10]. Thus, in our case, another mechanism different from that in athletes is considered to be the cause of the onset of the fracture.
Diagnoses of the fractures are made with X-rays and MRI. The sensitivity of plain X-rays for navicular stress fractures is only 33% [3, 7]. In our case, the plain radiograph showed a clear fracture line.
The therapy for the navicular insufficiency fracture was performed non-operatively. Previously, we had experienced that conservative therapy for insufficiency fractures in patients with RA was an efficient treatment. A non-displaced fracture should be treated with conservative therapy if the patient is unable to be very active.
The ethical committee of Hamamatsu University School of Medicine authorized this work.
The authors have declared no conflicts of interest.
References
- Pentecost RL, Murray RA, Brindley HH. Fatigue, insufficiency, and pathologic fractures. J Am Med Assoc 1964;187:1001–4.
[Abstract/Free Full Text] - Ostlie DK, Simons SM. Tarsal navicular stress fracture in a young athlete: case report with clinical, radiologic, and pathophysiologic correlations. J Am Board Fam Pract 2001;14:381–5.[Medline]
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- Clayton ML. Surgery of the forefoot in rheumatoid arthritis. Clin Orthop 1960;16:136–40.[Medline]
- Towne LC, Blazina ME, Cozen LN. Fatigue fracture of the tarsal navicular. J Bone Joint Surg Am 1970;52:376–8.
[Abstract/Free Full Text] - Khan KM, Brukner PD, Kearney C, Fuller PJ, Bradshaw CJ, Kiss ZS. Tarsal navicular stress fracture in athletes. Sports Med 1994;17:65–76.[Web of Science][Medline]
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- Kapanji IA. The physiology of the joints. 2nd edn. Edinburgh: Churchill Livingstone, 1970.
- Coris EE, Kaeding CC, Marymont JV. Tarsal navicular stress injuries in athletes. Orthopedics 2003;26:733–7.
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