Bilateral stress fractures of femoral neck in non-athletes

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Chinese Journal of Traumatology 2013;16(2):113-117

Bilateral stress fractures of femoral neck in non-athletes: a report of four cases Monappa A Naik, Premjit Sujir, Sujit Kumar Tripathy*, Sandeep Vijayan, Shamsi Hameed, Sharath K Rao 【Abstract】Femoral neck stress fractures (FNSFs) are rare, constituting only 5% of all stress fractures in young adults. These fractures are usually seen in athletes, military recruits and patients with underlying metabolic diseases. The treatment of FNSFs is still controversial because of the inherent complications associated with the treatment procedure. We came across 4 cases of bilateral FNSFs in non-athletic individuals who were manual labourers without underlying bony disorders. Two patients with FNSFs and coxa vara deformity on both sides were managed by subtrochanteric valgus osteotomy and dynamic hip screw fixation. One of the remaining two patients was treated by cannulated cancellous screw fixation on one side and subtrochanteric valgus osteotomy on the other side. The fourth patient received subtrochanteric valgus osteotomy on one

side and bipolar hemiarthroplasty on the other side after failed cannulated screw fixation. All the fractures healed without any complications. No evidence of avascular necrosis or arthritis was noted in our series. Subtrochanteric valgus osteotomy restores normal neck-shaft angle in patients suffering from FNSFs combined with coxa vara deformity. Moreover, it helps to bring the forces acting around the hip to normal biomechanical levels, leading to fracture union and better results. Replacement arthroplasty is recommended to patients who fail to achieve bony union after fixation. Key words: Fractures, stress; Femoral neck fractures; Coxa vara; Osteotomy

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To the best of our knowledge, bilateral FNSFs in middle-aged healthy nonathletic individuals have never been reported. We report four such cases without any premorbid conditions. This series is unique with respect to the different types of stress fractures in two femurs occurring simultaneously in the same individual and different methods of treatment. Meanwhile as the stress fractures are bilateral and of different types in the same individual, we have the opportunity to compare our results with the proposed methods of treatment mentioned in the literature. Informed consent has been obtained from all patients to publish their data.

epetitive cyclic loading on bones causes stress fracture when essentially normal bones can not withstand abnormal stress (fatigue fracture) or abnormal bones become unable to bear normal loading. 1,2 Frequently these injuries are reported in sports person (10% of injuries) and marathon runners (15% of injuries). 3 Femoral neck stress fractures (FNSFs) account for 5% of all stress fractures and 11% of femoral stress fractures in athletes.4 Most of the reported FNSFs are unilateral, and bilateral ones have been rarely reported. The sporadically reported cases are either individuals having bone defects like elderly people with osteopenia/osteoporosis, patients with underlying metabolic bone diseases or those having excessive bone activities like military personnel and long distance runners.2,4-9

DOI: 10.3760/cma.j.issn.1008-1275.2013.02.010 Department of Orthopaedics, Kasturba Medical College, Manipal, Karnataka, India (Naik MA, Sujir P, Tripathy SK, Vijayan S, Hameed S, Rao SK) *Corresponding author: Tel: 91-9342914292, Fax: 91820-2571934, Email: [email protected]

Chin J Traumatol 2013;16(2):113-117

CASE REPORT Case 1 A 38-year-old male, manual labourer (lifting heavy weights) presented with pain in both hips and inability to bear weight. He had no medical comorbidities. About one year ago he received an operation in another hospital for fracture of the left femoral neck sustained following a trivial trauma (Figure 1A). On evaluation, he had painful global restriction of left hip joint movement with 1 cm true supratrochanteric shortening and painful terminal restriction of right hip joint movement. Radio-

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graphs showed nonunion of the fracture of the left femoral neck with implant failure, joint space reduction and migration of screw into the joint space. On the right side, coxa vara deformity with compression type of FNSF was observed (Figure 1B). The implants were removed from the left hip and an uncemented bipolar hemiarthroplasty was performed. Fracture on the right side was treated by subtrochanteric valgus osteotomy and dynamic hip screw (DHS) fixation (Figure 1C). The neck-shaft angle of right femur was restored to 135 degrees from preoperative 114 degrees. Postoperatively, the patient was kept non-ambulant for 6 weeks and partial weight bearing with bilateral axillary crutches was started after that. Follow-up radiographs at 6 months showed fracture healing on right side with no signs of femoral head avascular necrosis (AVN). At the end of 2 years and 4 months, the patient had pain-free full range of hip movements and he was able to squat as well as sit cross-legged as needed in daily activities. Case 2 A 38-year-old lady, housemaid, presented with 6 months history of pain in both hip joints and inability to bear weight on the right side for 3 months after a trivial fall. The pain was insidious in onset and progressive in nature. She used to carry pots of water over her both waists for long distances until she fell down and developed severe pain. However, she denied any menstrual irregularities and there was no systemic illness. On examination, painful global restriction of movements at the right hip joint and 1 cm true supratrochanteric shortening was noted. On the left side, terminal flexion and rotation were restricted. Radiographs showed displaced type of stress fracture with varus collapse of the right


femoral neck and compression type of stress fracture on the left side. A subtrochanteric valgus osteotomy with DHS fixation on the right side and in situ fixation with three cancellous screws on the left side were done in the same sitting. The neck-shaft angle of the right femur was restored to 130 degrees. Postoperative rehabilitation program was just as same as Case 1. Follow-up X-rays at 3 months showed good union of fractures on both sides with no evidence of AVN. At one year’s time, she had normal and pain-free movements of the hip joint. Case 3 A 48-year-old housemaid came to us with a history of bilateral hip pain for 4 months. Her complaints and history were similar to those of Case 2. Movements of the right hip joint were painfully restricted and there was 1 cm supratrochanteric shortening with global restriction of left hip movements. On admission, she was unable to bear weight on her left hip and the movements of the right hip were painful. Radiographs showed compression type of stress fracture of the right femoral neck and displaced type of stress fracture on the left side (Figure 2A). She underwent bilateral subtrochanteric valgus osteotomy and fixation with DHS in two different sittings. Postoperative radiographs showed restoration of neck-shaft angle of right femur to 133 degrees and 130 degrees on left side. She was kept on non-weight bearing for 6 weeks followed by partial weight bearing with bilateral axillary crutches for another 6 weeks. At 6 months’ follow-up she had pain-free movements of both hips and X-rays showed sound fracture union without radiological evidence of AVN (Figure 2B).

Figure 1. Caes 1. A: Plain radiograph of pelvis with both hips showing varus angulated displaced stress fracture of the left femoral neck and varus angulated compression type of stress fracture of the right femoral neck. B: Plain radiograph showing left femoral neck with failed osteosynthesis. C: Postoperative radiograph showing bipolar hemiarthroplasty on left side and subtrochanteric valgus osteotomy of right femur fixed with DHS and restoration of normal neck-shaft angle.

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DISCUSSION

Figure 2. Case 3. A: Radiograph showing the compression type of stress fracture with varus deformity on the right and varus angulated displaced type of stress fracture of the femoral neck on the left side. B: Postoperative radiograph at six months followup time.

Case 4 A 40-year-old lady, manual worker by profession, came with insidious onset of pain in both hips of 3 months duration. Pain was more obvious on the left side. Her work involved squatting and sitting crosslegged for a long duration and lifting heavy objects, which aggravated her pain. She had a trivial fall at her work place after which she was unable to bear weight on her right lower limb. On examination, she had global restriction of movements and 1 cm supratrochanteric shortening of the right hip joint. Left hip showed joint line tenderness and painful restriction of rotation. Radiographs showed displaced FNSF on right side and undisplaced tension type of stress fracture on the left side. She underwent subtrochanteric valgus osteotomy with DHS fixation on both sides. Follow-up X-rays showed fracture union at 3 months with the neck-shaft angle being 134 degrees on the right side and 132 degrees on the left side. After one year, she had painless complete range of movements of the hip joints and was able to actively engage in her activities. Even after 17 years’ follow-up the patient was still active without any complain. The diagnoses in all the patients were made based on their history, clinical examination and radiographs. There was no history related to metabolic abnormalities or menstrual abnormalities in female patients. Routine haematological and biochemical investigations for metabolic parameters were carried out in all the cases to rule out metabolic or pathological causes of fracture. But due to financial constraints magnetic resonance imaging (MRI) or bone scan was done in none of the cases to confirm the diagnosis or identify femoral head AVN. Biopsy of materials from the fracture site was not indicative of any disease pathology.

FNSFs, first reported by Asal (1936), are not uncommon.10 However bilateral FNSFs are rare and only very few cases have been reported to date.2,5,7-9,11,12 This kind of fractures are commonly reported in military recruits, long distance runners and older adults. Besides it is found to be associated with abnormal anatomy, seizures, renal osteodystrophy, long or short t erm cort i cost ero i d use , am eno rrhoea and osteomalacia.6-9,13-15 Most of the reported bilateral stress fractures are of the insufficiency type and seen in elderly patients. Repetitive loading on the hip abductor muscles causes muscle fatigue and loss of shock absorption capacity. Muscle fatigue affects the position of the body’s centre of mass and alters the patterns of stress and strain in the femoral neck. Clinical and biomechanical studies have suggested this sequence of muscle fatigue and compensatory altered gait, leading to changes in stress application which plays as a common precipitating factor of FNSFs.2,10 All our patients are non-athletes and have no evidence of preexisting metabolic abnormality. However they are manual labourers involved in some kind of repetitive activities which might have produced abnormal stresses on both sides of their hips. We can see that bilateral fatigue FNSFs can also occur in non-athletes without underlying bone disorders. The earliest and most frequent symptom of FNSFs is anterior groin pain and the commonest sign is pain at extremes of hip movement.10 A high index of suspicion is needed as the radiographs may be normal at initial presentation. Usually, radiographs will reveal bone changes 2 or 3 weeks after the onset of symptoms.6 But its sensitivity is reported to be as low as 10% to 29%.15 MRI and bone scintigraphy are considered to be more beneficial for the early diagnosis. Bone scan is more sensitive in high bone remodelling areas, but it lacks specificity due to similar uptake in cases of infection, osteonecrosis and tumours.5,7,14,15 MRI is considered to be 100% sensitive, specific and more accurate in early diagnosis and differentiation from tumour and infection.6,7,14,16 Recently quantitative ultrasound bone density test has been shown to be able to predict future stress fractures. 6 However, according to our experience, we think that once the fracture is evident in

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the initial radiographs, there is no need for further imaging modalities to confirm the diagnosis. But it is mandatory to investigate and rule out systemic and metabolic causes for the bilateral insufficiency fractures. The ignorance of the minor symptoms and delay in seeking medical help in our series probably explain the different types (stages) of their bilateral fractures. It is also notable that stress fractures, even though symptomatic, are not disabling unless they become displaced acutely and /or the biomechanics of the hip joint are altered. Classifications of FNSFs are successively put forward by Devas (1965), Blickenstaff and Morris (1966) and Fullerton and Snowdy (1983) (Table 1).4,10 Compression fractures show evidence of internal callus on the inferior aspect of the femoral neck, take longer time to progress and are mechanically stable. While ten-

sion fractures start on the superior aspect, progress quickly and can lead to displacement.4,6,10 Displaced fractures are associated with complications like delayed union, nonunion, AVN of the femoral head and refracture.6,8,15,17 The trivial traumas which increase the symptoms, warranting that requirements of treatment in our cases are probably occurred due to the displacement or varus collapse of the tension type of stress fractures. Even though, a precise explanation cannot be given since it is noteworthy that there is a coincidence of fall and varus displacement of the fracture on the same side in our series. Except in one patient (left hip in Case 2), all the other cases showed varying amount of varus deformity in the neck-shaft region on the radiographs in spite of complete or incomplete fractures. This varus deformity can alter the biomechanics of hip joint. Radiologically no AVN was noted in our cases.

Table 1. Classification of stress fractures of femoral neck Devas (1965) Based on

Biomechanics

Blickenstaff and Morris (1966) Degree of dis placement and

Fullerton and Snowdy (1983) Biomechanics and degree of displacement

radiograph Type I

Compression fracture on

Callus + No fracture line

Compression fracture on inferior aspect of neck

Fracture line across the neck

Tension fracture on superior aspect of neck

inferior aspect of neck Type II

Transverse

or calcar without displacement Type III

-

Completely displaced fracture

Treatment of FNSFs is always a matter of debate. Compression type of stress fractures is usually treated conservatively. As for tension type of fractures, despite some available reports supporting conservative management of undisplaced ones,15 many advocate prophylactic surgical fixation. Displaced stress fractures need urgent surgical fixation. This tailored treatment is acceptable for unilateral FNSFs. But in active individuals with bilateral FNSFs, prolonged bed rest is not advisable or reliable, even fractures are undisplaced. Surgical fixation of these fractures and early ambulation of young active individuals are necessary. However, complications like AVN, refracture, varus collapse and pseudarthosis have been reported after stabilization with multiple screws or compression hip screw devices. Old displaced stress fractures usually have callus at the fracture site, which makes the anatomical closed reduction (restoring neck-shaft angle) nearly impossible. At the same time open reduction of these fractures has shown a higher incidence of AVN.6

Displaced fracture

All our cases presented late and had displacement with varus angulation of the fractures, which are poor prognosticating factors. Simple stabilization of these fractures would not have been beneficial to obtain union or avoid AVN. The issue of stabilizing these fractures without increasing the risk of AVN and nonunion can be achieved by combining osteosynthesis (without open reduction) with subtrochanteric valgus osteotomy, thereby correcting the anatomical deformity at the neckshaft region and realigning the fracture into a more horizontal position favouring the union and increasing the vascularity. In view of the varus angulation noted in all our patients (except left hip in Case 2), we employed the same principle and stabilized the osteotomy and fracture with DHS device and started early weight bearing. In Case 1, where the screw penetrated into the left hip joint with noticeable hip joint reduction and femoral neck resorption, bipolar hemiarthroplasty was performed because of financial constraints. In Case 2, the undisplaced left hip fracture without deformity was

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successfully treated with cancellous screw fixation. However, this technique should be judiciously used in displaced FNSF because of the risk of nonunion. Haddad et al14 reported a case of displaced stress fracture treated with closed reduction and cannulated screw fixation that later developed nonunion. Diwanji et al6 recommended that valgus subtrochanteric osteotomy is a good treatment option for FNSFs with gross displacement and varus angulation. Many authors argue that although subtrochanteric valgus osteotomy preserves blood supply to femoral head, it alters the biomechanics of hip joint, leading to early arthritis and making subsequent replacement surgery in such cases difficult. This mandates long term follow-up of all patients treated with subtrochanteric osteotomy. All the patients in this series are still under our follow-up. Nevertheless, the successful rate of subtrochanteric valgus osteotomy is satisfactory and can be considered as an ideal procedure in young middle-aged individuals.

2. Markey KL. Stress fractures. Clin Sports Med 1987;6(2): 405-25. 3. Matheson GO, Clement DB, McKenzie DC, et al. Stress fractures in athletes. A study of 320 cases. Am J Sports Med 1987;15(1):46-58. 4. Fullerton LR, Snowdy HA. Femoral neck stress fractures. Am J Sports Med 1988;16(4):365-77. 5. Bailie DS, Lamprecht DE. Bilateral femoral neck stress fractures in an adolescent male runner. A case report. Am J Sports Med 2001;29(6):811-3. 6. Diwanji SR, Kong IK, Cho SW, et al. Displaced stress fracture of the femoral neck treated by valgus subtrochanteric osteotomy: 2 case studies. Am J Sports Med 2007;35(9):156770. 7. Gurdezi S, Trehan RK, Rickman M. Bilateral undisplaced insufficiency neck of femur fractures associated with short-term steroid use: a case report. J Med Case Rep 2008;2:79. 8. Johansson C, Ekenman I, Tornkvist H, et al. Stress fractures of the femoral neck in athletes. The consequence of a delay in diagnosis. Am J Sports Med 1990;18(5):524-8.

In conclusion, the key to treating FNSFs is early and accurate diagnosis to prevent associated complications. FNSFs should be suspected in individuals who have recently performed vigorous repetitive activities or whose activity has increased in frequency or duration. It needs to be realized that bilateral FNSFs can occur in non-athletic active adults as well. It is important to look for all possible causes to rule out insufficiency fractures and confirm fatigue fractures in these conditions. The treatment modality should aim at correction and prevention of the deformity at the neck-shaft region of the femur. It is imperative to mobilize patients as early as possible which warrants stabilization of these fractures. Hence, there is no role of conservative treatment for FNSFs of any type when it is bilateral. We strongly recommend osteosynthesis for complete undisplaced fractures without deformity and osteosynthesis with valgus osteotomy for complete displaced fractures with varus angulation. Incomplete fractures with deformity needs correction of deformity by osteotomy. Compression type of incomplete fractures without deformity can be treated conservatively. As the tension type fractures are mechanically unstable, they undoubtedly need surgically fixation.

9. Karapinar H, Ozdemir M, Akyol S, et al. Spontaneous bilateral femoral neck fractures in a young adult with chronic renal failure. Acta Orthop Belg 2003;69(1):82-5. 10. Devas MB. Stress fractures of the femoral neck. J Bone Joint Surg Br 1965;47(4):728-38. 11. Miller LF. Bilateral stress fracture of the neck of the femur: report of a case. J Bone Joint Surg Am 1950;32(3):695-7. 12. Pihlajamaki HK, Ruohola JP, Kiuru MJ, et al. Displaced femoral neck fatigue fractures in military recruits. J Bone Joint Surg Am 2006;88(9):1989-97. 13. Chadha M, Balain B, Maini L, et al. Spontaneous bilateral displaced femoral neck fractures in nutritional osteomalacia—a case report. Acta Orthop Scand 2001;72(1):94-6. 14. Haddad FS, Mohanna PN, Goddard NJ. Bilateral femoral neck stress fractures following steroid treatment. Injury 1997;28 (9-10):671-3. 15. Ichikawa J, Amano R, Haro H, et al. Fatigue fracture of the bilateral femoral neck in the elderly. Orthopaedics 2008;31(11): 1141. 16. Zuckerman JD, Shin SS, Polatsch DB, et al. Concurrent bilateral femoral neck stress fractures and osteonecrosis of the hip. A case report. J Bone Joint Surg Am 2006;88(4):857-60. 17. Pihlajamaki HK, Ruohola JP, Weckstrom M, et al. Longterm outcome of undisplaced fatigue fractures of the femoral neck in young male adults. J Bone Joint Surg Br 2006;88(12):1574-9.

REFERENCES (Received July 23, 2012) 1. Knapp TP, Garrett WE Jr. Stress fractures: general concepts. Clin Sports Med 1997;16(2):339-56.

Edited by LIU Gui-e