Insufficiency fracture of the femoral head in patients with severe osteoporosis--report of 2 cases

Atraumatic fractures of the femur

Atraumatic fractures of femur, although not as common as traumatic fractures, are frequently encountered in the clinical practice. They present with non-specific symptoms and can be occult on initial imaging making their diagnosis difficult, sometimes resulting in complications. Overlapping terminologies used to describe these fractures may hamper effective communication between the radiologist and the clinician. In this article, we review various atraumatic fractures of femur, terminologies used to describe them, their imaging findings and differential diagnosis. The article also describes the aetiology, pathophysiology and relevant biomechanics behind these fractures. An approach to atraumatic femoral fractures has been outlined.

Predictors of cartilage degeneration in patients with subchondral insufficiency fracture of the femoral head: a retrospective study

Background

There is evidence that the cause of primary osteoarthritis (OA) is related to the changes in subchondral bone; however, the influence of subchondral insufficiency fracture (SIF) of the femoral head on the degeneration of the hip joint and the prognostic factors related to joint degeneration remain unclear. The objectives of this study were (1) to investigate the natural history of joint space width after the occurrence of SIF and (2) to investigate the associations between joint space narrowing and bone metabolic markers as well as magnetic resonance imaging (MRI) among the patients with SIF.

Methods

Between January 2010 and December 2019, 238 patients in whom band pattern of the femoral head were observed on MRI visited Hokkaido University Hospital. Among these patients, 44 hips in 41 patients were diagnosed with SIF and eligible for this retrospective study. We evaluated the joint space width (JSW) of the hip on the radiograph obtained at the first and last visits, length of the band lesion on MRI, bone mineral density by dual-energy X-ray absorptiometry, and bone metabolism markers. Similarly, the factors associated with the necessity of surgery and the progression of the narrowing of the joint space were evaluated.

Results

Fifteen of the 44 hips required total hip arthroplasty (THA). A significant decrease was observed in the JSW from the first visit to the final follow-up. Changes in the JSW were associated with the length of band patterns, serum type 1 procollagen-N-propeptide (P1NP), and tartrate-resistant acid phosphatase 5b (TRACP-5b) during diagnosis. Additionally, bone metabolic markers tended to be associated with the length of the band pattern.

Conclusions

SIF could cause joint space narrowing and hip OA. In addition to MRI findings as prognostic predictors of SIF, as previously described, bone metabolic markers were equally associated with changes in JSW, suggesting that these parameters could be useful in predicting the prognosis of SIF. Considering that bone metabolic markers trended to be associated with the length of band pattern, they might reflect the local severity.

Accumulation of microdamage and low bone mass in the femoral head as a cause of subchondral insufficiency fracture in a patient with osteogenesis imperfecta

Subchondral insufficiency fractures of the femoral head are generally considered to be osteoporosis-related fragility fractures. There have been reports of microfractures being found in subchondral bone on pathological examination. However, the mechanism of these microfractures is not known. In this report, we describe a patient with osteogenesis imperfecta who developed a subchondral insufficiency fracture of the femoral head after a fall that had resulted in a subcapital femoral neck fracture. Bipolar hemiarthroplasty was performed, and bone at the femoral head and neck was sampled for pathophysiological examination. Hematoxylin and eosin staining revealed microfractures and microcallus in the subchondral bone in the femoral head, indicating healing of a subchondral insufficiency fracture before the subcapital femoral neck fracture. Moreover, decreased bone volume and accumulated microdamage were observed in the subchondral bone but not in the cancellous bone in the femoral neck. These findings suggest that subchondral insufficiency fracture of the femoral head is a stress fracture caused by accumulation of microdamage in fragile subchondral bone.

Osteoclast-related markers in the hip joint fluid with subchondral insufficiency fracture of the femoral head

Similar to the radiological findings in rapidly destructive arthrosis of the hip joint (RDA), subchondral insufficiency fracture of the femoral head (SIF) can result in progressive femoral head collapse of unknown etiology. We thus examined the osteoclast activity of hip joint fluid in SIF with progressive collapse in comparison with that in RDA. Twenty-nine hip joint fluid samples were obtained intraoperatively with whole femoral heads from 12 SIF patients and 17 RDA patients. SIF cases were classified into subgroups based on the presence of ≥2 mm collapse on preoperative radiographs: SIF with progressive collapse (n = 5) and SIF without progressive collapse (n = 7). The levels of tartrate-resistant acid phosphatase (TRACP)-5b, interleukin-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-9 were measured. The number of multinuclear giant cells at the subchondral region was histopathologically assessed using mid-coronal slice of each femoral head specimen. The median levels of all markers and the median number of multinuclear giant cells in SIF with progressive collapse were significantly higher than those in SIF without progressive collapse, while there were no significant differences in SIF with progressive collapse versus RDA. Regression analysis showed that the number of multinuclear giant cells was positively correlated with the level of TRACP-5b in joint fluid. The present study demonstrated the possible association of increased osteoclast activity with the existing condition of progressive collapse in SIF, which was quite similar to the findings in RDA, indicating that increased osteoclast activity may reflect the condition of progressive collapse in SIF as well as RDA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2987-2995, 2018.

Computed tomography findings of subchondral insufficiency fractures of the femoral head

Objectives

The objective of this study was to describe the appearance of Subchondral insufficiency fracture (SIF) by computed tomography (CT).

Methods

Images of 52 consecutive patients diagnosed with SIF were retrospectively reviewed. CT was available for five patients (7 cases).

Results

Corresponding to a low-intensity band on MR images, a radiolucent or sclerotic band was observed on CT images.

Conclusion

The present study is the first to report CT findings of SIF. A radiolucent or sclerotic band was observed on CT images. The results of the present study provide useful information for diagnosis of SIF.

Fat-suppressed T2-weighted MRI appearance of subchondral insufficiency fracture of the femoral head

OBJECTIVE

Our aims were to investigate the imaging appearance of subchondral insufficiency fracture (SIF) of the femoral head based on fat-suppressed T2-weighted MRI, and evaluate its correlation with the clinical outcomes following conservative treatment.

MATERIALS AND METHODS

We retrospectively evaluated 40 hips in 37 patients with SIF of the femoral head (12 males and 25 females; mean age 55.8 years, range 22-78 years). MRI examinations were performed within 3 months after the onset of hip pain. Using fat-suppressed T2-weighted imaging, we evaluated the hips for the intensity of the subchondral bone (corresponding to the area superior to the low intensity band on T1-weighted images) as well as bone marrow edema, joint effusion, and presence of the band lesion. We then correlated the intensity of the subchondral bone with clinical outcomes.

RESULTS

The hips were classified into three types based on subchondral intensity on fat-suppressed T2-weighted images: type 1 (21 hips) showed high intensity, type 2 (eight hips) showed heterogeneous intensity, and type 3 (11 hips) showed low intensity. The mean period between pain onset and MRI examination was significantly longer for type 2 hips than for type 1. Healing rates were 86 % for type 1, 75 % for type 2, and 18 % for type 3.

CONCLUSION

SIF cases were classified into three types based on subchondral intensity on fat-suppressed T2-weighted imaging performed within 3 months after pain onset. Type 3 SIF tended to be intractable to conservative treatment compared to type 1 and type 2.

Common site of subchondral insufficiency fractures of the femoral head based on three-dimensional magnetic resonance imaging

OBJECTIVES

The objective of this study was to investigate the common sites of subchondral insufficiency fractures of the femoral head (SIF) based on three-dimensional (3-D) reconstruction of MR images.

MATERIALS AND METHODS

In 33 hips of 31 consecutive patients diagnosed with SIF, 3-D reconstruction of the bone, fracture, and acetabular edge was performed using MR images. These 3-D images were used to measure the fractured areas and clarify the positional relationship between the fracture and degree of acetabular coverage.

RESULTS

The fractured area in the anterior portion was significantly larger than in the posterior area. In 11 cases, the fractures contacted the acetabular edge and were distributed on the lateral portion. The indices of acetabular coverage (center-edge angle and acetabular head index) in these cases were less than the normal range. In the remaining 22 cases, the fractures were apart from the acetabular edge and distributed on the mediolateral centerline of the femoral head. The majority of these cases had normal acetabular coverage.

CONCLUSIONS

The common site of SIF is the anterior portion. In addition, two types of SIF are proposed: (1) Lateral type: the contact stress between the acetabular edge and lateral portion of the femoral head causes SIF based on the insufficient acetabular coverage, and (2) Central type: the contact stress between the acetabular surface and the mediolateral center of the femoral head causes SIF independent from the insufficiency of acetabular coverage. These findings may be useful for considering the treatment and prevention of SIF.

Subchondral insufficiency fractures of the femoral head: associated imaging findings and predictors of clinical progression

OBJECTIVES

To characterize the morphology and imaging findings of femoral head subchondral insufficiency fractures (SIF), and to investigate clinical outcomes in relation to imaging findings.

METHODS

Fifty-one patients with hip/pelvis magnetic resonance (MR) images and typical SIF characteristics were identified and reviewed by two radiologists. Thirty-five patients had follow-up documentation allowing assessment of clinical outcome. Subgroup comparisons were performed using regression models adjusted for age and body mass index.

RESULTS

SIF were frequently associated with cartilage loss (35/47, 74.5 %), effusion (33/42, 78.6 %), synovitis (29/44, 66 %), and bone marrow oedema pattern (BMEP) (average cross-sectional area 885.7 ± 730.2 mm(2)). Total hip arthroplasty (THA) was required in 16/35 patients, at an average of 6 months post-MRI. Compared to the THA cohort, the non-THA group had significantly (p < 0.05) smaller overlying cartilage defect size (10 mm vs. 29 mm), smaller band length ratio and fracture diameters, and greater incidence of parallel fracture morphology (p < 0.05). Male gender and increased age were significantly associated with progression, p < 0.05.

CONCLUSIONS

SIF were associated with synovitis, cartilage loss, effusion, and BMEP. Male gender and increased age had a significant association with progression to THA, as did band length ratio, fracture diameter, cartilage defect size, and fracture deformity/morphology.

KEY POINTS

• Femoral head subchondral insufficiency fractures (SIF) frequently require total hip arthroplasty (THA). • SIF frequently coexist with synovitis, cartilage loss, and bone marrow oedema pattern. • SIF cartilage defect size, band length ratio, and fracture diameter/morphology can predict progression risk.

Subchondral insufficiency fracture of the femoral head in males

OBJECTIVE

Subchondral insufficiency fracture of the femoral head (SIF) has been reported to be observed mainly in the elderly osteoporotic females and most of the studies on SIF have been made based on female patients. The purpose of this study is to document the clinical characteristics of SIF observed in male patients.

PATIENTS AND METHODS

Between 2001 and 2011, we have diagnosed 39 consecutive SIF hips in our department, based on imaging studies and/or histologic examinations. Among them, 14 hips (35.8%) were of male SIF patients. Their clinico-radiological characteristics were reviewed.

RESULTS

The age range in male SIF patients was 16-62 (ave. 44 years), while that in females was 22-84 (ave. 66 years) (p < 0.001). In male patients, 12 out of 14 hips (86%) healed by non-surgical treatments, while 2 hips (14%) underwent surgical treatments (one case: total hip arthroplasty, and one: anterior rotational osteotomy). On the other hand, in female patients 12 out of 25 (48%) healed, while surgical treatments and/or progression of a collapse were observed in 13 hips (52%) (p < 0.05). Both body mass index and bone mineral density showed no significant difference between male and female SIF patients.

CONCLUSIONS

SIF in male is observed mainly in their 40s, and their prognosis seems to be good as compared to that in females.

Bone mineral density in patients with destructive arthrosis of the hip joint

Recent reports have shown the existence of subchondral insufficiency fracture in rapidly destructive arthrosis of the hip joint (RDA), and the findings suggest that osteopenia is related to the pathogenesis of the rapid progression of this disease. Therefore, we measured bone mineral density (BMD) in RDA patients. We measured BMD of the lumbar spine, radius, and calcaneus using dual-energy X-ray absorptiometry in 19 patients with RDA and 75 with osteoarthritis of the hip (OA) and compared BMD at different skeletal sites between RDA and OA patients. No significant differences were observed in BMD of the lumbar spine, ultradistal radius, mid-radius, and calcaneous between the RDA and OA groups. Our data suggest that RDA is not accompanied by generalized osteoporosis. Factors other than generalized bone status, for example, BMD around the affected hip joint before destruction, need to be analyzed to elucidate the pathophysiological mechanism of RDA.

Subchondral insufficiency fractures of the femoral head

A subchondral insufficiency fracture (SIF) of the femoral head is a recently proposed concept, which needs to be differentiated from osteonecrosis. Clinically, SIF has generally been observed in the osteoporotic elderly women or renal transplant recipients. Radiographical changes are not obvious in its early phase, however, some cases undergo subchondral collapse (crescent sign). On the T1-weighted magnetic resonance images, a low intensity band is one of the characteristic imaging appearances, which corresponds histologically to the fracture line and associated fracture repair tissue. Therefore, the shape of the low intensity band generally tends to be irregular, disconnected, and convex to the articular surface. The prognosis of SIF is not clearly established. Some cases show resolution of the symptoms by the conservative treatments, while other cases show rapid progression of the collapse such as rapidly progressive arthrosis of the hip.

Multiple stress fractures of the lower extremity in healthy young men

Stress fractures result from abnormal stresses imposed on normal bones by the continued and repeated actions of muscles or from normal stresses imposed on abnormal bones. The risk factors that can cause such stress fractures include excessive use, such as, in soldiers or athletes, nutritional deficiencies, and endocrine disorders. In addition, disease may arise from long-standing rheumatoid arthritis, osteoporosis, corticosteroid therapy, joint stiffness or contracture, or the correction of angular deformity. In these cases, stress fractures may occur in one area or multiple areas. However, no case of multiple stress fractures in a young man who was not a professional athlete and who had no stress fracture risk factor, such as, an endocrine disease, has been previously reported.

Prognostic factors associated with a subchondral insufficiency fracture of the femoral head

OBJECTIVE

The aim of this study was to identify the risk factors associated with the prognosis of a subchondral insufficiency fracture of the femoral head (SIF).

METHODS

Between June 2002 and July 2009, 25 patients diagnosed with SIF were included in this study. Sequential radiographs were evaluated for the progression of collapse. Clinical profiles, including age, body mass index, follow-up period and Singh's index, were documented. The morphological characteristics of the low-intensity band on T(1) weighted MRI were also examined with regards to four factors: band length, band thickness, the length of the weight-bearing portion and the band length ratio (defined as the proportion of the band length to the weight-bearing portion of the femoral head in the slice through the femoral head centre).

RESULTS

Radiographically, a progression of collapse was observed in 15 of 25 (60.0%) patients. The band length in patients with progression of collapse [22.5 mm; 95% confidence interval (CI) 17.7, 27.3] was significantly larger than in patients without a progression of collapse (13.4 mm; 95% CI 7.6, 19.3; p<0.05). The band length ratio in patients with progression of collapse (59.8%; 95% CI 50.8, 68.9) was also significantly higher than in patients without a progression of collapse (40.9%; 95% CI 29.8, 52.0; p<0.05). No significant differences were present in the other values.

CONCLUSION

These results indicate that the band length and the band length ratio might be predictive for the progression of collapse in SIF.

Subchondral insufficiency fracture of the femoral head may be associated with hip dysplasia: a pilot study

BACKGROUND

Subchondral insufficiency fracture of the femoral head occurs mainly in elderly patients with osteoporosis. Spontaneous resolution is observed after nonoperative treatment in some patients whereas other show progressive joint destruction requiring THA. Several studies report the occurrence of subchondral insufficiency fracture of the femoral head in dysplastic hips.

QUESTIONS/PURPOSES

We asked whether the extent of hip dysplasia or osteoporosis was greater in patients with subchondral insufficiency fracture of the femoral head than in normal control subjects.

PATIENTS AND METHODS

We compared the clinical and imaging findings of 13 patients with subchondral insufficiency fractures of the femoral head and 12 patients scheduled for TKA with asymptomatic hips. Age, gender, and body mass index were comparable in the two groups.

RESULTS

Higher mean Sharp angles, lower acetabular head indices, lower center-edge angles, and higher acetabular roof angles in patients with subchondral insufficiency fracture of the femoral head than in those with asymptomatic hips suggested a greater degree of hip dysplasia. Bone mineral density and serum levels of Type I collagen cross-linked N-telopeptide and bone alkaline phosphatase were similar in the two groups.

CONCLUSIONS

We speculate an excessive amount of stress on the acetabular edge from dysplasia may be associated with the occurrence of subchondral insufficiency fracture of the femoral head.

Collapsed subchondral fatigue fracture of the femoral head

Several etiologies can lead to a subchondral fracture of the femoral head, which may result in femoral head collapse and degenerative change. This article evaluates the follow-up results of subchondral fatigue fractures of the femoral head in which femoral head collapse occurred. The study shows that collapsed subchondral fatigue fractures of the femoral head have a benign clinical course quite unlike that of collapsed osteonecrosis of the femoral head.

Bilateral subchondral insufficiency fracture of the femoral head

Subchondral insufficiency fracture of the femoral head is a rarely reported lesion, often confused with osteonecrosis, transient osteoporosis of the hip, or rapidly destructive coxarthrosis. However, almost all the previous reports about this lesion have documented unilateral cases. We report the clinical and histological features of bilateral subchondral insufficiency fracture of the femoral head in a 68-year-old woman. She reported a sudden pain in her left hip without apparent trauma. An anteroposterior radiograph 2 weeks after the onset of pain in the left hip shows a subchondral collapse of the femoral head. The entire femoral head was depicted as a low intensity area on a T1-weighted image, and there was a subchondral linear pattern of low signal intensity with a convex shape to the articular surface. On T2-weighted image, the entire femoral head was depicted as a high intensity area, and on T1-weighted image, a linear low signal intensity pattern was noted. The patient underwent hemiarthroplasty. Cross-section of the femoral head showed a fracture line identified in the subchondral area. Although the patient's postoperative course was favorable, she had idiopathic pain in the right hip. A lateral radiograph 3 weeks after the onset of pain in the right hip shows irregularity at the surface of the femoral head. Cross-section of the right femoral head showed a concave fracture line in the subchondral bone. Based on these findings, bilateral subchondral insufficiency fracture of the femoral head was diagnosed.

Subchondral insufficiency fracture of the femoral head after total knee arthroplasty in a patient with rheumatoid arthritis

We report an 80-year-old woman with rheumatoid arthritis (RA) who was found to have subchondral insufficiency fracture of the right femoral head after total knee arthroplasty (TKA). Initially, plain radiographs showed no obvious changes, but magnetic resonance imaging (MRI) revealed an irregular, discontinuous, low-intensity band on T1-weighted images of the right hip. She underwent hemiarthroplasty of the hip. This report describes a rare case of subchondral insufficiency fracture of the femoral head after TKA in a patient with RA.

Rapidly destructive coxopathy after subchondral insufficiency fracture of the femoral head

Rapidly destructive coxopathy (RDC) is a rare disorder, and its pathophysiology is unknown. Here, we report a case of RDC evaluated by roentgenography and magnetic resonance imaging, from the onset of hip pain without changes on roentgenograms, to the terminal stage with collapse of the femoral head. Our serial radiological findings clearly illustrate the entire process of RDC, especially the initial stage. Subchondral insufficiency fracture of the femoral head seems to be an important preliminary event in the development of RDC.

Subchondral fractures of the femoral head: a review of seven cases

OBJECTIVE

To describe the main characteristics of subchondral fractures of the femoral head.

CASE-REPORTS

The seven patients, five women and two men, with a mean age of 50 years (37-76 years), presented with mechanical pain in the groin. Bone loss was the main risk factor. Two patients had postmenopausal osteoporosis (including one with a history of ovariectomy at 30 years of age), two had osteoporosis induced by glucocorticoid therapy given after transplantation (liver and allogeneic bone marrow, respectively), one had an ACTH-producing adenoma, and one had femoral osteopenia at a site of topical glucocorticoid therapy for atopic dermatitis. The remaining patient had osteopenia and a history of smoking. Phosphate and calcium levels were normal in five patients. One patient had isolated hypocalciuria and another had moderate proximal tubular disease with phosphate wasting and hypercalciuria. Magnetic resonance imaging (MRI) disclosed a subcapital line of low signal on T1- and T2-weighted sequences surrounded by an area of variable size generating low signal on T1 images and high signal on T2 images, with postgadolinium enhancement, denoting marrow edema. Complete elimination of weight bearing for 6 weeks, symptomatic agents, and treatment of the underlying causes of bone insufficiency were used in all seven patients. Mean follow-up was 2.4 years (range, 11-39 years). No cases of osteonecrosis were recorded.

CONCLUSION

Several cases of subchondral fracture have been reported in the literature. Bone insufficiency was the main risk factor in all the patients.

Subchondral insufficiency fractures of the femoral head

The aim of this study was to increase awareness of, and to show the variable clinical and radiological features of, subchondral insufficiency fractures of the femoral head. The clinical and radiological findings in 7 patients with subchondral insufficiency fractures of the femoral head were reviewed retrospectively. The diagnosis was confirmed histologically in 4 patients. Radiographs were performed in all patients, MRI in 5 and scintigraphy in 4 patients. Radiographs showed varying degrees of femoral head collapse in 4 patients. In the remaining 3 patients radiographs showed a normal femoral head, regional osteoporosis and focal sclerosis, respectively. Magnetic resonance imaging showed a low-signal band on T1- and T2-weighted images in the subchondral bone adjacent or parallel to the articular surface associated with bone marrow oedema. Scintigraphy showed increased uptake in the femoral head. Insufficiency fractures of the femoral head are easily overlooked or confused with avascular necrosis and, when there is significant joint destruction, osteoarthritis. Unsuspected insufficiency fracture of the femoral head can lead to significant and rapid loss of bone stock in osteoporotic patients waiting for arthroplasty for osteoarthritis. Increased awareness of this condition will hopefully lead to earlier diagnosis and a successful outcome of conservative treatment.

Insufficiency subchondral fracture of the femoral head: report of 4 cases and review of the literature

Insufficiency subchondral fractures are nontraumatic flattened lesions in the superolateral area of the femoral head, occurring in healthy adults. These lesions were recently described and are an infrequent cause of acute hip pain. We report on 4 patients who were diagnosed with an insufficiency subchondral fracture. All the patients showed radiographic progression of the lesion after 4 months, and 3 patients required a total hip arthroplasty. The etiology and the natural history of these rare lesions remain to be elucidated. These lesions should be differentiated from osteonecrosis and transient osteoporosis, because treatment and prognosis may differ.

Spontaneous osteonecrosis of the knee: the result of subchondral insufficiency fracture

BACKGROUND

Spontaneous osteonecrosis of the knee is a superficial subchondral lesion classically seen in the medial femoral condyle; in general, it is markedly different in its clinicopathological presentation from the classic wedge-shaped subchondral osteonecrotic lesions seen in the hip, knee, and other joints. Recent reports on subchondral insufficiency fracture of the femoral head, which has marked morphological similarities with spontaneous osteonecrosis of the knee, led us to reevaluate a series of patients who had had operative treatment because of a clinical and pathological diagnosis of spontaneous osteonecrosis of the knee.

METHODS

We reviewed the cases of fourteen patients who had had operative treatment of spontaneous osteonecrosis of the knee in order to reevaluate the gross and histological morphology of this lesion. The patients included eight women and six men who ranged in age from fifty-nine to eighty-eight years. In all patients, the diagnosis of spontaneous osteonecrosis of the knee had been based on clinical presentation, imaging studies, and pathological findings. The appearance of the lesion on plain radiographs was categorized into four stages, which corresponded to the gross and histological findings. In stage 1, the radiographic appearance is normal; in stage 2, a radiolucent oval area is seen subchondrally or there is slight flattening of the convexity of the condyle, or both; in stage 3, the radiolucent area is expanded and is surrounded by a sclerotic halo; and in stage 4, secondary osteoarthritic changes are apparent.

RESULTS

No patient had a stage-1 lesion. Three patients, all of whom had a stage-2 lesion, were considered to have a subchondral insufficiency fracture of the medial femoral condyle. Another six patients, all of whom had a stage-3 lesion, were considered to have a subchondral fracture and associated focal osteonecrosis that was confined to the area between the fracture line and the articular surface. The remaining five patients, three of whom had a stage-3 lesion and two of whom had a stage-4 lesion, had indeterminate findings because the lesion had become detached from the condyle.

CONCLUSIONS

Our histopathological findings suggest that the primary event leading to spontaneous osteonecrosis of the knee is a subchondral insufficiency fracture and that the localized osteonecrosis seen in association with this disease is the result of a fracture.

Subchondral insufficiency fracture of the femoral head: a differential diagnosis in acute onset of coxarthrosis in the elderly

OBJECTIVE

To document subchondral insufficiency fracture (SIF) of the femoral head and investigate its frequency.

METHODS

The study was based on a retrospective review of 464 removed femoral heads (from 419 patients) with both radiologic and histologic evidence of subchondral collapse. Gross photographs, specimen radiographs, and histologic sections were reevaluated in all cases. Available clinical notes and imaging studies were also reviewed.

RESULTS

Ten cases previously diagnosed as osteonecrosis were reinterpreted as SIF on a histopathologic basis. All of these patients were women over 65 years old (average age 75) with osteopenia. The initial symptom was acute onset of hip pain. Radiologically, a subchondral collapse, mainly in the superolateral segment of the femoral head, was noted. Magnetic resonance imaging, available in 3 cases, showed diffuse low intensity on T1-weighted images and high intensity on T2-weighted or fat-suppressed images. Bone scintigraphy, available in 4 cases, showed increased uptake in the femoral head. Histopathologically, a 1.0-2.5-cm long linear whitish gray zone, comprising fracture callus and granulation tissue, was found beneath the subchondral bone end plate. There was no evidence of antecedent osteonecrosis.

CONCLUSION

The results of this study indicate that SIF should be included in the differential diagnosis of acute onset of coxarthrosis in the elderly.