C. S. H. Grace, K. W. B. Kelvin, C. T. Wei & T. B. Yeow

Transcription

1 Stress fracture of the ulna associated with bisphosphonate therapy and use of walking aid C. S. H. Grace, K. W. B. Kelvin, C. T. Wei & T. B. Yeow Osteoporosis International With other metabolic bone diseases ISSN X DOI /s

2 Your article is protected by copyright and all rights are held exclusively by International Osteoporosis Foundation and National Osteoporosis Foundation. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com. 1 23

3 DOI /s CASE REPORT Stress fracture of the ulna associated with bisphosphonate therapy and use of walking aid C. S. H. Grace & K. W. B. Kelvin & C. T. Wei & T. B. Yeow Received: 16 March 2014 /Accepted: 1 May 2014 # International Osteoporosis Foundation and National Osteoporosis Foundation 2014 Abstract We report a case of a stress fracture of the ulna secondary to long-term bisphosphonate therapy and walking cane. Physicians need to have a high index of suspicion of stress fractures occurring in patients complaining of chronic upper limb pain if they are on bisphosphonate therapy and are using walking aids. Stress fractures of the upper extremities are rare and are usually associated with athletes; however, a few recent case reports have shown an association between stress fractures of the upper extremities and the use of walking aids. The association between increased incidence of upper extremity stress fractures and the use of both bisphosphonates and walking aids in patients has not been well studied, with only one previously reported case. Here, we report a case of a complete stress fracture of the ulna in a 77-year-old female, premorbidly ambulant with walking cane, on long-term bisphosphonates without any pre-existing medical conditions which could result in secondary causes of bone loss. Investigations did not reveal any causes of pathological fracture. This fracture is attributed to the use of long-term bisphosphonate therapy in conjunction with the use of a walking cane. This case highlights the importance of entertaining the possibility of such fractures occurring in any patient who is on bisphosphonate therapy presenting with stress fractures of the upper extremity. Keywords Bisphosphonates. Stress fractures. Upper extremities. Walking aids C. S. H. Grace (*) National University Health System, 1E, Kent Ridge Road, Singapore , Singapore grace_sh_chiang@nuhs.edu.sg K. W. B. Kelvin: C. T. Wei : T. B. Yeow St. Luke s Hospital, 2 Bukit Batok Street 11, Singapore , Singapore Introduction Osteoporosis is a major global public health problem especially with the rapidly aging population; the World Health Organization (WHO) data predicts average life expectancy of men to be 75 years and women to be 80 years. Worldwide, osteoporosis affects approximately 200 million women [1]and causes more than 8.9 million fractures annually leading to increased morbidity and mortality [2]. Osteoporosis-related fractures cause significant medical and personal toll on individuals and economic burden on the nation; the cumulative cost over the next two decades is estimated to be US$474 billion [3]. Osteoporosis can be diagnosed early and treated before fractures occur. There is a range of drug treatments available for osteoporosis, of which, bisphosphonates are the first-line therapy and the most widely used in view of their anti-fracture efficacy [4]. While studies have shown that bisphosphonates prevent future vertebral and non-vertebral fractures in patients with osteoporotic fractures, post-menopausal women with osteoporosis, and men with osteoporosis [5, 6], there has been increasing evidence of bisphosphonate use leading to atypical fractures especially of the femur [7, 8]. Limited data on atypical fractures of long bones other than the femur is available [9 11]. Prolonged bisphosphonate therapy has been associated with over-suppression of bone turnover and increased skeletal fragility [9]. Stress fractures result from the suppression of intracortical remodeling, hence impairing normal bone healing [10]. We report a case of atraumatic stress fracture of the ulna secondary to long-term alendronate use in a patient using a walking cane. Case summary A 77-year-old Chinese female was started on alendronate for osteoporosis in Nine years after starting alendronate,

4 she suffered an atraumatic fracture of the right ulna requiring surgical fixation. The patient had noted pain of her right forearm for 3 months; however, pain had worsened when she had transferred more weight to her right forearm whilst ambulating with a walking cane. X-ray of the right forearm showed a transverse fracture of the proximal shaft of the right ulna with increased sclerosis aroundthefracture(fig.1). She has a past medical history of multiple fractures. She had sustained a left medial tibial condyle and fibula neck fracture in 1999 after a fall which was managed conservatively. In 2001, she was discovered to have multiple vertebral compression fractures and she had been experiencing lower back pain and an X-ray was done. In 2004, she sustained a right intertrochanteric fracture after falling and underwent a bipolar hemiarthroplasty. Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DEXA) revealed T-scoreoflumbarspinetobe 3.8 with a density of 0.54 g/ sq cm 2 and she was started on alendronate. In 2010, she sustained a left distal radial fracture after a mechanical fall, which was managed conservatively. Her risk factors were reviewed. She was quite active premorbidly, ambulating with walking cane for 6 years and carrying out daily activities of living independently. She did not have premature menopause. She is a non-smoker and nondrinker. She was not on any other long-term medications and no history of steroid use. There was no history of significant weight change or change in bowel habits. During physical examination, there was deformity of the right forearm with tenderness, but neurovascularly intact. Laboratory work-up showed corrected calcium 2.28 mmol/ L, 8:00 a.m. cortisol 435 nmol/l, thyroid stimulating hormone 2.16 miu/l, parathyroid hormone 4.6 pmol/l, and 25- hydroxy vitamin D level 35.8 μg/l. Myeloma panel was not suggestive of multiple myeloma. Her bone density did not decrease between 2005 and In 2012, the bone density of the spine was 0.56 g/sq cm 2 with a T-score of 3.8. Bone scan showed that there was no scintigraphic evidence of bone metastasis. Magnetic resonance imaging of the right elbow showed a midshaft ulna fracture; no underlying pathological lesions were seen (Fig. 2). In view of the atraumatic nature of the fracture, X-ray findings distinctive of atypical fractures, and further investigations excluding other causes of atypical fractures, the diagnosis of atypical ulna shaft fracture secondary to long-term alendronate use was made and alendronate was discontinued. The fracture was fixed with plates and screws. However, 3 weeks after surgical fixation, deformity over the right forearm open reduction internal fixation site was noted. X-ray of the right ulna showed a peri-implant fracture with displacement of screws. She subsequently underwent removal of the implant and re-fixation with bone grafting. She recovered well and was later discharged to a rehabilitation hospital for physical and occupational therapy. Fig. 1 Right forearm X-rays show a slightly displaced transverse fracture of the proximal shaft of the right ulna with increased sclerosis around the fracture. The bones appear diffusely osteopenic

5 Fig. 2 Magnetic resonance imaging of the right elbow shows a stress fracture of the midshaft of the ulna fracture as a linear area of low signal intensity. There isoedema within the soft tissues and at the site of the fracture. No underlying pathological lesions were seen Discussion Long-term bisphosphonate use has been found to increase the relative risk of atypical fractures [7, 8]. While there is strong evidence to suggest that bisphosphonate use is associated with atypical fractures of the femur [11, 12], the relation between bisphosphonate use and atypical fractures of the upper limb has not been well studied [13]. Prolonged use of alendronate may be associated with stress fractures [5]; it is believed that the long-term over-suppression of bone turnover impairs the ability of bone to remodel, causing microdamage to persist which compromises bone strength leading to stress fractures [11]. Common clinical features of atypical fractures associated with bisphosphonate use are prodromal pain occurring for weeks to months prior to the fracture, typically sharp and well localized [11]. These fractures are usually atraumatic. Radiographic features of atypical fractures associated with bisphosphonate use are a transverse fracture line, beaking of the cortex on one side and bilateral thickened diaphyseal cortices [9]. Upper extremity stress fractures are rare and can occur in athletes [14, 15] and those using walking aids [9, 16, 17]. It is postulated that the likely mechanism of injury with walking aids is a combination of tractional and torsional force, together with direct pressure on the proximal forearm bones. In our patient, it is probable that the fracture was a stress fracture secondary to both long-term alendronate use and walking aids. This patient had presented with an isolated transverse midshaft ulna fracture; however, it was atraumatic unlike the usual mechanism of injury for isolated midshaft ulna fractures which is a blunt trauma to the forearm when it is being held in protection across the face. Furthermore, she presented with classical symptoms associated with atypical bisphosphonate fractures; radiographic findings likewise showed the typical transverse fracture line and increased sclerosis around the fracture. Investigations done for this patient did not reveal any cause of pathological fractures or secondary causes of bone loss. The patient reported here was ambulating with a walking cane. The stress fracture is likely to have resulted from the high tensional stress caused by weight bearing on the walking cane where the wrist is in a position of flexion and axial load is increased though the ulna. The longterm use of alendronate in this case may have resulted in increased brittleness of the bones as bone turnover is inhibited, thus leading to increased mineralization and accumulation of microdamage [8]. This case highlights that physicians need to have a high index of suspicion of upper extremity stress fractures occurring in patients who complain of chronic upper limb pain if they are on bisphosphonate therapy and are using walking aids. To facilitate early detection, it is essential that both physicians and patients be aware of the possibility of such fractures occurring and the signs and symptoms associated with these fractures. It is critical to comprehensively investigate such patients with radiographs looking for stress reaction and, if necessary, advanced imaging such as bone scan or magnetic resonance imaging should be considered. Bisphosphonates should be discontinued in patients with stress fractures secondary to bisphosphonate therapy. Conflicts of interest None.

6 References 1. Kanis JA (2007) WHO Technical Report, University of Sheffield, UK: Johnell O, Kanis JA (2006) An estimate of the worldwide prevalence and disability associated with osteoporotic fractures. OsteoporosInt 17: Burden of Musculoskeletal Diseases in the United States: Prevalence, Societal and Economic Cost. Rosemont, IL, American Academy of Orthopaedic Surgeons. February Cummings SR, Black DM, Thompson DE et al (1998) Effect of alendronate on risk of fracture in women with low bone density but without vertebral fractures: results from the Fracture Intervention Trial. JAMA 280: Black DM, Schwartz AV, Ensrud KE et al (2006) Effects of continuing or stopping alendronate after 5 years of treatment: the Fracture Intervention Trial Long-term Extension (FLEX): a randomized trial. JAMA 296: Meta-analyses of therapies for postmenopausal osteoporosis. II. Meta-analysis of alendronate for the treatment of postmenopausal women. Cranney A, Wells G, Willan A, Griffith L, Zytaruk N, Robinson V, Black D, Adachi J, Shea B, Tugwell P, Guyatt G, Osteoporosis Methodology Group and The Osteoporosis Research Advisory Group. EndocrRev. 2002;23(4): Girgis CM, Sher D, Seibel MJ (2010) Atypical femoral fractures and bisphosphonate use. N Engl J Med 362: Visekruna M, Wilson D, McKiernan FE (2008) Severely suppressed bone turnover and atypical skeletal fragility. J Clin Endocrinol Metab 93: Shane E (2010) Evolving data about subtrochanteric fractures and bisphosphonates. N Engl J Med 362: Shane E, Burr D, Abrahamsen B, et al. Atypical subtrochanteric and diaphyseal femoral fractures: Second report of a task force of the American Society for Bone and Mineral Research. J Bone Miner Res Giusti A, Neveen AT H, Papapoulos SE (2010) Atypical fractures of the femur and bisphosphonate therapy: a systematic review of case/case series studies. Bone 47(2): Giusti A, Hamdy NAT, Dekkers OM, Ramautar SR, Dijkstra S, Socrates E, Papapoulos SE (2011) Atypical fractures and bisphosphonate therapy: a cohort study of patients with femoral fracture with radiographic adjudication of fracture site and features. Bone 48(5): Yavropoulou MP, Giusti A, Ramautar SR, Dijkstra S, Hamdy NAT, Papapoulos SE (2012) "Low energy fractures of the humeral shaft and bisphosphonate use.". J Bone Miner Res 27(6): Iwamoto J, Takeda T (2003) Stress fractures in athletes: review of 196 cases. J Orthop Sci 8(3): Brukner P (1998) Stress fractures of the upper limb. Sports Med 26(6): Sørensen L (1992) "Bilateral symmetrical stress fracture of the ulna". Ugeskr Laeger 154(26): Venkatanarasimha N, Kamath S, Kambouroglou G, Ostlere SJ (2009) "Proximal ulna stress fracture and stress reaction of the proximal radius associated with the use of crutches: a case report and literature review". J Orthop Traumatol 10(3):