Femoral Neck Stress Fractures: MRI Risk Factors for Progression

Femoral neck fracture in sickle cell anemia: A comprehensive case study

Key Clinical Message

The significance of taking femoral neck stress fractures into account as a possible consequence in sickle cell anemia patients is underscored by this case report. In this high-risk group, early identification, timely diagnosis, and suitable care are crucial for averting major problems and improving results. When sickle cell anemia patients complain with hip or groin discomfort, healthcare practitioners should keep a high index of suspicion for femoral neck stress fractures to assure prompt management and prevent long-term impairment.

Abstract

Sickle cell disease (SCD) is a prevalent genetic hemoglobinopathy with significant global implications, affecting a substantial portion of the population. Avascular necrosis of the femoral head is a common complication in SCD, leading to severe joint damage and immobility. This case report is of a 20-year-old male who presented with severe hip pain due to a femoral neck stress fracture, which progressed to a complete fracture. This patient had a past medical history of sickle cell anemia and a malunited subtrochanteric fracture that resulted in shortening, external rotation, and a limping gait. Surgical treatment via subtrochanteric osteotomy with fixation using a dynamic hip screw with or without iliac crest bone graft was planned, with a satisfactory reduction and closure of the fracture gap, postoperatively. In cases of sickle cell anemia patients, bone complications such as both osteonecrosis and stress fractures are common. As a healthcare provider, it is important to manage and address these not only through medical interventions, but also through counseling and patient education. Patients must be reminded about the importance of compliance with medical advice to avoid progression or recurrence of complications.

Case Series: Bilateral Operative Femoral Neck Stress Fractures in Marine Corps Recruits

Bone stress injuries are well-documented injury patterns among U.S. Armed Forces recruits because of the rapid increase in frequency and intensity of bone-impacting activities throughout training. In the recruit population, femoral neck stress fractures are of great concern because of their propensity to progress, displace, and lead to lifelong complications like avascular necrosis. We present two cases of bilateral operative femoral neck stress fractures. The first is of a 28-year-old male Marine Corps recruit who experienced bilateral groin pain during the first week of training. He was found to have bilateral grade 4 femoral neck stress fractures with concomitant effusions. Operative management was pursued with bilateral percutaneous pinning. For this patient, one hip had classically indicated operative involvement while on the contralateral hip the decision to operate was based on recent literature predicting progression based on the presence of a joint effusion. The second case is of a 23-year-old male Marine Corps recruit who experienced hip pain in the final few weeks of training. He was also found to have bilateral grade 4 femoral neck stress fractures with concomitant effusions and was similarly operated on. To the best of our knowledge, this is the first reported operative bilateral femoral neck stress fracture case series in a military-aged patient in the literature. A high clinical suspicion for femoral neck stress injuries with early diagnostic imaging for high-risk groups was important in these cases and ultimately led to timely definitive management for this patient.

Consensus and Equipose in the Management of Military Trainee Femoral Neck Stress Fractures: A Survey of Military Surgeons

BACKGROUND

Femoral neck stress fractures (FNSFs) are a unique injury pattern not commonly treated in the civilian trauma population; however, it is particularly high with military trainees engaged in basic combat training. To date, no study has surveyed a population of military orthopedic surgeons on treatment preferences for military service members (SMs) with FNSF.

QUESTIONS

We aim to evaluate the extent of clinical equipoise that exists in the management of these injuries, hypothesizing that there would be consensus in the factors dictating surgical and non-surgical intervention for FNSF.

PATIENTS AND METHODS

A 27-question survey was created and sent to U.S. military orthopedic surgeon members of the Society of Military Orthopaedic Surgeons. The survey was designed in order to gather the experience among surgeons in treating FNSF and identifying variables that play a role in the treatment algorithm for these patients. In addition, seven detailed, clinical vignettes were presented to further inquire on surgeon treatment preferences. Binomial distribution analysis was used to evaluate for common trends within the surgeon's treatment preferences.

RESULTS

Seventy orthopedic surgeons completed the survey, the majority of whom were on active duty status in the U.S. Military (82.86%) and having under 5 years of experience (61.43%). Majority of surgeons elected for a multiple screw construct (92.86%), however the orientation of the multiple screws was dependent on whether the fracture was open or closed. Management for compression-sided FNSF involving ≥50% of the femoral neck width, tension-sided FNSF, and stress fractures demonstrating fracture line progression had consensus for operative management. Respondents agreed upon prophylactic fixation of the contralateral hip if the following factors were involved: Complete fracture (98.57%), compression-sided fracture line >75% (88.57%), compression-sided fracture line >50-75% with hip effusion (88.57%), contralateral tension-sided fracture (87.14%), and compression-sided fracture line >50-75% (84.29%). An FNSF < 50% on the contralateral femoral neck or a hip effusion was indeterminate in surgeons indicating need for prophylactic fixation. Majority of surgeons (77.1%) utilized restricted toe-touch weight-bearing for postoperative mobility restrictions.

CONCLUSIONS

Consensus exists for surgical and non-surgical management of FNSF by U.S. military orthopedic surgeons, despite the preponderance of surgeons reporting a low annual volume of FNSF cases treated. However, there are certain aspects in the operative and non-operative management of FNSF that are unanimously adhered to. Specifically, our results demonstrate that there is no clear indication on the management of FNSF when an associated hip effusion is involved. Additionally, the indications for surgically treating contralateral FNSF are unclear.

LEVEL OF EVIDENCE

IV.

Bone marrow edema of the hip: a narrative review

Bone marrow edema (BME) of the hip is a radiological-clinical condition with symptoms ranging from asymptomatic to severe, and it is characterized by increased interstitial fluid within the bone marrow, usually at the femur. Depending on the etiology it can be classified as primary or secondary. The primary cause of BME is unknown, while the secondary forms include traumatic, degenerative, inflammatory, vascular, infectious, metabolic, iatrogenic, and neoplastic etiologies. BME could be classified as reversible or progressive. Reversible forms include transient BME syndrome and regional migratory BME syndrome. Progressive forms include avascular necrosis of the femoral head (AVNH), subchondral insufficiency fracture, and hip degenerative arthritis. The diagnosis can be difficult, because at the beginning, the outbreak of hip pain, typically acute and disabling without any prior trauma or exceptional physical activity, is poorly supported by radiographic findings. MRI is the gold standard, and it shows an area of intermediate signal on T1-weighted MRI scans and a high signal on T2-weighted scans, usually lacking sharps margins. In the reversible form, BME is typically self-limiting, and it can be managed conservatively by means of pharmacological and physical therapy. Surgery is generally required for progressive forms in patients who failed non-operative treatment, and it ranges from femoral head and neck core decompression to total hip arthroplasty.

Femoral neck stress fracture return to activity and the effect of metabolic dysfunction on recovery: A systematic review

Background

Femoral neck stress fractures are rare fractures traditionally found in athletes and military personnel. There is limited literature on return to activity.

Objectives

To report return to activity rates and times, and long-term outcomes for femoral neck stress fractures reported in the literature. To examine the effects of bone metabolic dysfunction and surgical management on return to activity following FNSF.

Research design & methods

A systematic literature review of case reports and case series on adults with femoral neck stress fracture that were diagnosed by gross fracture line on X-ray or gold-standard diagnosis with MRI was conducted. Initial search was limited to articles published from January 1997 to Jan 2023 listed in Medline, Embase, and Scopus. Additional articles were manually added via search of retained paper sources. Patient demographics, fracture type, return to activity time, and surgical vs non-surgical treatment modality were collected. In addition, long-term outcomes and metabolic effects, if reported, were abstracted.

Results

A total of 40 case reports or case series were retained. 123 stress fractures of the femoral neck from 103 patients were compiled. Of the 103 patients, data on return to activity at least one year following treatment was available for 53 patients. 71% (37/53) of those with long-term follow-up information returned to full pre-injury activity. 24% (13/53) at long-term follow-up had functional recovery but did not return to pre-injury activity due to residual pain. 4% (3/53) had disabling pain. Metabolic workup information was available for 36 patients.

Conclusion

Long-term follow-up and return to activity information following FNSF treatment are not commonly reported. Based on the available data, outcomes appear benign with most returning to full activity. There is a clear need for standardization of follow-up periods and hip function measure after FNSF treatment. Additionally, a sizable proportion of FNSF occurred in a new population of low-activity individuals with abnormal bone metabolism, which warrants further exploration.

The Presence of Hip Joint Effusion on MRI Is Predictive of a Grade 4 Femoral Neck Stress Injury

INTRODUCTION

One of the most debilitating types of bone stress injuries is those occurring at the femoral neck. This problem occurs in the military population with much higher incidence than in the normal population and is of great concern to military medical providers. Early detection and accurate diagnosis are key in protecting soldiers and recruits from sustaining a potentially career-ending fracture. In a case study, a 16-year-old elite male distance runner presented with hip pain. MRI found hip joint effusion but was unremarkable for marrow edema and a low-signal fracture line. The initial diagnosis was acute arthritis; however, a follow-up radiograph 1 month later, after the patient had been refraining from running, confirmed a significant non-displaced compression-side Grade 4 femoral neck stress injury (FNSI). In light of the case study and our similar clinical experience, we tested the hypothesis that an MRI study positive for an FNSI, combined with the evidence of a hip joint effusion, is indicative of a Grade 4 FNSI, even without visualization of a low-signal intensity fracture line on T1 or short tau inversion recovery images.

MATERIALS AND METHODS

Recruits in Army Basic Combat Training were included in the investigation if 1) diagnosed with a unilateral FNSI, 2) had an initial positive MRI for an FNSI, 3) had a positive bone scan for uptake in the femoral neck area (to validate the diagnosis), 4) had no other hip/pelvis injuries, and 5) had a follow-up MRI within 60 days. Hip joint effusion was defined as 1) ≥2-mm measurable difference in the thickness of fluid along the length of the involved femoral neck when compared to the contralateral uninvolved femoral neck on the initial MRI; 2) visibly assessed as a prominent collection of fluid distending the posterior hip joint capsule on the initial MRI coronal short tau inversion recovery sequence (called the "flash sign").

RESULTS

A total of 162 recruits met the study inclusion criteria. For the detection of a Grade 4 FNSI on the first MRI, the sensitivity, specificity, and positive predictive value of the measured joint effusion criteria were 0.52, 0.94, and 0.89, respectively. or the non-measured flash sign, these values were 0.70, 0.83, and 0.80, respectively.

CONCLUSIONS

Both the measured hip joint effusion criteria and the non-measured flash sign were predictive of a Grade 4 FNSI and may be useful in clinical evaluation.

Iron-induced Hypophosphatemic Osteomalacia-An Atypical Case of Bilateral Femoral Stress Fractures

We present a case of a 61-year-old healthy man who had bilateral femoral neck insufficiency fractures attributed to repeated iron transfusions, causing iron-induced hypophosphatemic rickets, requiring surgical intervention. Atraumatic insufficiency fractures present a diagnostic dilemma in orthopaedics. Chronic fractures with no acute precipitating trigger can often go unrecognized until complete fracturing or displacement occurs. Early identification of the risk factors in conjunction with a comprehensive history, clinical examination, and imaging can potentially avoid these serious complications. Atraumatic femoral neck insufficiency fractures have been sporadically reported in the literature, often unilateral and attributed to the use of long-term bisphosphonates. Through this case, we elaborate on the relatively unknown link between iron transfusions and insufficiency fractures. This case highlights the importance of early detection and imaging of such fractures from an orthopaedic perspective.

Imaging of Overuse Injuries of the Hip

Overuse injuries of the hip are common, and clinical diagnosis may be difficult because of overlapping and nonspecific clinical symptoms. Imaging can play an essential role in guiding diagnosis and management. Femoroacetabular joint structural abnormalities result in various conditions that can predispose patients to early development of osteoarthritis. Repetitive stress on the skeletally immature hip can result in apophyseal injuries. Notable nonosseous overuse hip pathologies include athletic pubalgia, trochanteric bursitis, and injuries involving the iliopsoas myotendinous unit. Timely diagnosis of overuse injuries of the hip can facilitate improved response to conservative measures and prevent irreversible damage.

Comparison of Ultrasonography to MRI in the Diagnosis of Lower Extremity Bone Stress Injuries: A Prospective Cohort Study

OBJECTIVE

To determine the sensitivity and specificity of ultrasound imaging (USI) compared to the reference-standard of MRI in the diagnosis of bone stress injury (BSI).

METHODS

A prospective blinded cohort study was conducted. Thirty seven patients who presented to an academic sports medicine clinic from 2016 to 2020 with suspected lower-extremity BSI on clinical exam underwent both magnetic resonance imaging (MRI) and USI. Participant characteristics were collected including age, gender and sport. Exclusion criteria included contraindication for dedicated MRI, traumatic fracture, or severe tendon or ligamentous injury. The primary outcome measure was BSI diagnosis by USI. An 8-point assessment system was utilized on USI for diagnosis of BSI, and the Fredericson and Nattiv²² criteria were applied to classify MRI findings.

RESULTS

Thirty seven participants who met study criteria were consented to participate. All participants completed baseline measures. Using MRI, there were 30 (81%) athletes with a positive and seven participants with a negative BSI diagnosis. The most common BSIs in the study were in the metatarsal (54%) and tibia (32%). Compared to MRI, USI demonstrated 0.80 sensitivity (95% confidence interval [CI], 0.61-0.92) and 0.71 specificity (95% CI, 0.29-0.96) in detecting BSI, with a positive predictive value of 0.92 (95% CI, 0.75-0.99) and negative predictive value of 0.45 (95% CI, 0.17-0.77).

CONCLUSIONS

USI is a potentially useful point-of-care tool for practicing sports medicine providers to combine with their clinical evaluation in the diagnosis of BSIs. Further research is ongoing to determine the role of USI in follow-up care and return-to-play protocols.

Surgically Treated Femoral Neck Stress Fractures Are Likely to Result in Military Separation During Basic Combat Training

BACKGROUND

Femoral neck stress fractures are a common condition affecting military service members, most noticeably during basic combat training. Previous studies have investigated the risk factors for femoral neck stress fracture development in basic trainees and outcomes associated with treatment; however, few studies have focused on operatively treated femoral neck stress fracture in the military trainee. Doing so would be important not only for the military, but also providers caring for athletes, such as distance runners, who have a heightened risk for femoral neck stress fracture development.

QUESTIONS/PURPOSES

(1) What proportion of US Army trainees completing basic combat training at Fort Jackson, SC, USA, who undergo surgery for femoral neck stress fracture during basic training subsequently leave military service because of the injury? (2) What factors are related to the patient or the fracture are associated with a higher likelihood of military separation? (3) What factors on the initial MRI are associated with progression of the stress fracture extent?

METHODS

A retrospective study of a longitudinally maintained database of stress injuries involving basic combat trainees from a single military post was reviewed over a 3-year period. Inclusion criteria included basic trainees undergoing surgery for a femoral neck stress fracture between January 2018 and June 2020 with a minimum of 1-year follow-up. Surgery was indicated for service members with complete and tension-sided femoral neck stress fractures and those with high risk compression-sided stress fractures, generally representing fractures involving more than 50% of the femoral neck width. Over the study period, 57 service members (51% [29 of 57] women with a mean age of 24 years) underwent surgery for a femoral neck stress fracture, and all 57 had a minimum of 1-year follow-up. Identified service members underwent independent data collection including injury and radiographic parameters based on chart and imaging review. Documented fracture line progression on repeat imaging was present in 39% of service members, with a mean fracture line progression of 55% of the femoral neck width. Service members were subdivided based upon the ability to return to military service at 1 year. Univariate analysis was performed using patient and injury variables to identify factors associated with the ability to return to military service.

RESULTS

Overall, 58% (33 of 57) of service members who had a femoral neck stress fracture treated surgically underwent military separation. A higher proportion of service members who demonstrated fracture line progression leading to surgical treatment remained in the military (58% [14 of 24] versus 30% [10 of 33]; odds ratio 0.3 [95% confidence interval (CI) 0.1 to 0.9]; p = 0.03). With the numbers available, we found no other patient- or fracture-related variables associated with military separation, although we suspect we may have been underpowered on some of these comparisons, in particular gender (61% [20 of 33] of individuals separated after surgery for this injury were women compared with 38% [9 of 24] who were retained; OR 2.6 [95% CI 0.9 to 7.56]; p = 0.09). The extent of osseous edema on T1-weighted imaging in association with a hip effusion demonstrated a significant positive correlation with final fracture percentage (r = 0.62; p = 0.003).

CONCLUSION

Military service members with a femoral neck stress fracture initially managed nonoperatively but with progression of the fracture line requiring surgical intervention were more likely to return to military duties and complete basic combat training, suggesting that early diagnosis of femoral neck stress fractures may be associated with better functional recovery after surgical treatment. Additionally, the extent of the osseous edema on initial MRI T1-weighted imaging sequences may help predict the final extent of femoral neck stress fractures on repeat imaging. Further investigations should incorporate patient-reported outcomes and further explore factors associated with fracture progression and the inability to return to active duty or sport.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Stress fractures of the femoral neck in adults: an observational study on epidemiology, treatment, and reoperations from the Swedish Fracture Register

BACKGROUND AND PURPOSE

Stress fractures of the femoral neck (sFNFs) are uncommon injuries. Studies on sFNFs are rare. We describe the demographics, classification, treatment, reoperation rates, and mortality in a cohort of sFNF patients from the Swedish Fracture Register (SFR).

PATIENTS AND METHODS

We included 146 patients ≥ 18 years of age with an sFNF registered in the SFR between 2011 and 2020. The cohort was linked with the Swedish Arthroplasty Register and reviewed using medical records and radiographs. We assessed the presence of disorders of bone remodeling, duration of symptoms, fracture classification, treatment, reoperations, and mortality.

RESULTS

The mean age was 58 years (21-96), 75% were women and the median duration of symptoms was 23 days (1-266). 40% of patients had disorders of bone remodeling. 54% were undisplaced (uFNF), 30% displaced (dFNF), and 16% basicervical (bFNF). 14% of patients < 60 years were treated nonoperatively, by internal fixation (IF) in 77% and by arthroplasty in 10%. Patients ≥ 60 years were treated nonoperatively in 10%, IF in 40%, and arthroplasty in 49%. Nonoperative treatment was reserved for uFNFs or bFNFs, resulting in 35% receiving late surgery. The overall secondary or late surgery rate was 19%. Mortality was 2% at 90 days and increased to 3% at 1 year.

INTERPRETATION

sFNF has a biphasic age distribution. One-third of patients presented with a displaced FNF and those managed nonoperatively for an undisplaced sFNF were at risk of late surgery. The mortality rates for patients with these injuries was low.

Femoral Neck Stress Fractures: An Updated Review

Femoral neck stress fractures represent a relatively rare spectrum of injuries that most commonly affect military recruits and endurance athletes. If unrecognized and if proper treatment is not initiated, this condition carries potentially devastating consequences. Patients will typically present with an insidious onset, atraumatic hip, and groin pain that is relieved with rest. The condition may be initially misdiagnosed because radiographs are often normal. Magnetic resonance imaging has demonstrated superior specificity, sensitivity, and accuracy compared with other diagnostic modalities in identifying and classifying stress fractures of the femoral neck. Treatment algorithms are based on the MRI fracture morphology and presence of an intra-articular effusion. Nonsurgical management consists of a period of non-weight-bearing followed by gradual return to activity. Surgical management consists of prophylactic fracture fixation with cannulated screws to prevent fracture progression. If left untreated, patients may progress to a complete displaced femoral neck fracture, which can be associated with complications that include nonunion, osteonecrosis of the femoral head, and long-term disability. These poor outcomes emphasize the importance of early diagnosis and treatment of incomplete femoral neck stress fractures.

Femoral Neck Stress Fractures in Athletes and the Military

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Femoral neck stress fractures (FNSFs) are an infrequent condition in athletic and military populations.

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A high index of suspicion with liberal use of magnetic resonance imaging (MRI) is vital for early recognition and treatment initiation.

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An associated hip effusion on MRI is a risk factor for an evolving stress injury and requires close assessment and consideration for repeat MRI.

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Stress reactions and stable, incomplete FNSFs (<50% of femoral neck width) can be treated nonsurgically.

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Surgical intervention is accepted for high-risk, incomplete (≥50% of femoral neck width), and complete FNSFs.

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Overall, there is a paucity of high-quality literature on the rates of return to activity following FNSF.

Hip fractures following intramedullary nailing fixation for femoral fractures

INTRODUCTION

Proximal peri-implant femoral fractures occur following intramedullary nailing (IMN) fixation for trochanteric, femoral shaft, and distal femoral fractures. However, analyses of secondary hip fractures (SHFs) using large clinical samples are lacking. Therefore, we aimed to report the incidence and clinical outcomes of SHF after nailing fixation (IMN or cephalomedullary nailing [CMN]) for overall femoral fractures. In addition, we focused on IMN for femoral shaft fractures and investigated the risk factors for SHF.

METHODS

This multicenter, retrospective, cohort study included 2,293 patients aged > 60 years who underwent nailing fixation for femoral fractures. The primary outcome was the incidence of SHF. In the assessment of clinical outcomes, we evaluated reoperation and the regaining of walking ability following SHF management. In addition, we conducted multivariable logistic regression analyses to examine the association between risk factors and SHF.

RESULTS

Seventeen (0.7%) patients had SHFs, including 12 femoral neck fractures and 5 trochanteric fractures. Antegrade IMN was the most common type of nailing fixation. Multivariable analysis demonstrated that the absence of femoral head fixation was significantly associated with the incidence of SHF following IMN for femoral shaft fractures (odds ratio, 17.0; 95% confidence interval, 1.9-2265.7; p=0.006). In the assessment of clinical outcomes, there were two reoperations (16.7%) in the secondary femoral neck fracture group. Patients with secondary trochanteric fractures tended to have a lower probability of regaining walking ability than those with secondary femoral neck fractures (20% vs. 50%).

CONCLUSIONS

In this multicenter study, the incidence of SHF after nail fixation for femoral fractures was 0.7%. The absence of femoral head fixation was significantly associated with SHF, and the clinical outcomes were poor. Therefore, femoral head fixation at the initial IMN fixation for femoral fractures may be a fixation option for surgeons to consider as an SHF prevention measure.

Bilateral stress fracture of the femoral neck in association with simultaneously developing osteonecrosis of the femoral head: a case report

Background

Femoral neck stress fractures are rare and often recognized as overuse injuries that occur in young athletes or military personnel. A case following osteonecrosis of the femoral head is quite rare; even more uncommon is its occurrence in the bilateral hips. Magnetic resonance imaging has been established as the preferred tool for diagnosing nondisplaced femoral neck stress fracture due to overuse injury. Magnetic resonance imaging was also useful to detect the initial lesion even in this case, although the etiology was different between overuse injury and insufficiency fracture.

Case presentation

A 41-year-old Japanese woman diagnosed with bilateral early stage idiopathic osteonecrosis of the femoral head was observed non-weight-bearing as much as possible using a stick. However, her pain and difficulty in walking progressed. Bilateral femoral neck stress fractures were subsequently detected by magnetic resonance imaging. The fracture initially appeared as a spot of bone marrow edema at the medial site of the femoral neck, and then developed into a fracture line. The patient underwent internal fixation of both hips with sliding hip screws to stabilize the stress fractures. In addition, the preparatory reaming served as core decompression of the femoral heads, as well as being treatment for osteonecrosis. Her bone mineral density and 25-hydroxy vitamin D values were low for her age. We administered eldecalcitol and teriparatide acetate. Her symptoms mostly improved, and the fracture lines and necrotic lesions on magnetic resonance imaging reduced at 5 months after the surgery.

Conclusions

Bilateral femoral neck stress fractures are a very rare condition and are often missed. It is important to listen to the patient’s complaints and perform an appropriate examination. We encountered a case of bilateral femoral neck stress fracture that occurred in a patient with early stage osteonecrosis of the femoral head, and were able to observe progression of stress fracture since before fracture occurred. This is considered to be the first report to capture imaging changes before and after the onset.

Implementation of a novel MRI protocol for diagnosing femoral neck fractures in high energy femoral shaft fractures: One year results

INTRODUCTION

Preliminary results using a novel rapid-sequence MRI to diagnose ipsilateral femoral neck fractures in patients sustaining high-energy femoral shaft fractures have been favorable compared to radiographic and CT imaging alone. To evaluate and optimize this new institutional imaging protocol further, we reviewed our results one year after implementation.

METHODS

Rapid-sequence MRI was added to the imaging evaluation of patients with high-energy femoral shaft fractures without femoral neck fractures identified on radiographs or CT imaging. Data was retrospectively reviewed from a consecutive series of patients who met inclusion criteria.

RESULTS

From September 2018 through September 2019, 114 patients sustained 121 high-energy femoral shaft fractures. The average patient age was 29.9 years, 73.7% (84/114) of patients were male, and 16.5% (20/121) were open fractures. Of patients indicated for a rapid-sequence MRI, 86% (92/107) underwent MR imaging. 5% (6/121) of patients had an ipsilateral femoral neck fracture identified on radiographs alone. Three additional femoral neck fractures were identified with CT imaging for an initial incidence of 7.4% (9/121). MRI identified 10 additional non-displaced femoral neck fractures, three complete and seven incomplete fractures, for an incidence of 15.7% (19/121). All identified femoral neck fractures were stabilized.

DISCUSSION/CONCLUSION

The addition of rapid-sequence MRI of the pelvis in patients with high-energy femoral shaft fractures reliably increases the diagnosis of ipsilateral femoral neck fractures not identified with standard imaging. There were no cases of missed/delayed femoral neck fractures in patients with a negative MRI. This new imaging protocol effectively and safely improves the diagnosis of this injury pattern.

Tension-Sided Femoral Neck Stress Fracture in an Adolescent with Vitamin D Deficiency and Osteomalacia: A Case Report

CASE

An adolescent girl presented with groin pain without any history of trauma. Imaging showed a tension-sided stress fracture of the femoral neck. Vitamin D deficiency (VDD), and raised alkaline phosphatase and parathyroid hormone levels were found. Pain relief was not achieved with nonoperative treatment. Considering the risk of fracture progression and displacement, the fracture was fixed with cannulated cancellous screws. Fracture healed without any complications.

CONCLUSION

A tension-sided femoral neck stress fracture, with VDD and osteomalacia, is a rare cause of hip pain in an adolescent. Surgical fracture stabilization is necessary in addition to medical treatment.

Stress Fractures of the Hip and Pelvis

Stress fractures refer to overuse injuries of bone resulting from repetitive mechanical stress. Stress fractures of the hip and pelvic region, while relatively uncommon, have become increasingly recognized in certain populations, particularly long-distance runners and military recruits. The diagnosis of such injuries can be challenging, often hampered by a nonspecific physical examination and limited sensitivity of plain radiography. Early recognition is important to direct appropriate management, lessen time lost from sport, and avoid potential complications. The present article reviews the epidemiology, diagnosis, and management of bone stress injuries of the hip and pelvis, specifically the sacrum, pubic ramus, and femoral neck.

Synovial Inclusion Cyst Mimicking a Femoral Neck Stress Fracture in an Active Duty Servicemember: A Case Report

CASE

A 19-year-old female servicemember with history of ischiopubic rami stress fractures was referred to orthopaedic surgery for magnetic resonance imaging findings concerning for a tension-sided femoral neck stress fracture. However, her history and symptoms were discordant with the diagnosis of stress fracture. The patient was managed with protected weight-bearing for 6 weeks with gradual return to physical activity.

CONCLUSION

Prophylactic surgical fixation is advocated for the management of tension-sided femoral neck stress fractures. However, surgeons should consider a broader differential diagnosis, to include a synovial inclusion cyst, when the clinical presentation is not consistent with a stress fracture.

Bilateral Atypical Tension-sided Femoral Neck Stress Fractures in a Military Recruit

A case report of a Marine Recruit with bilateral atypical tensile-sided femoral neck stress fracture. The patient was treated nonoperatively with protected weightbearing following an established protocol that included close observation with serial exams and advanced imaging. He recovered uneventfully and was able to return to running. He was eventually diagnosed with bilateral femoral acetabular impingement syndrome at the end of his treatment course demonstrating a growing association warranting further investigation.

Current concept of stress fractures with an additional category of atypical fractures: a perspective review with representative images

Stress fractures have traditionally been classified into three categories: fatigue fractures due to overuse of bone with normal elastic resistance; insufficiency fractures due to everyday physiological stress on fragile bone with poor elastic resistance; and pathologic fractures due to bone weakness involving tumors. The concept of atypical fractures has emerged and is considered a type of stress fracture. However, there has been some inconsistency in interpretation when using the traditional classification of stress fractures, and atypical femoral fractures (AFFs) can potentially be classified into subtypes: "typical" AFFs involving bone turnover suppression due to specific drugs (e.g. bisphosphonates) and fragility fractures of the bowed femoral shaft. In this article, the classification of stress fractures is redefined with the addition of atypical fractures as a fourth category, in which biological activity for fracture healing is absent, to promote consistent understanding and interpretation of clinical conditions involving stress fractures.

Internal Fixation of Pauwels Type-3 Undisplaced-incomplete Insufficiency Femoral Neck Fractures with Cephalomedullary Nails

Femoral neck stress fractures are rare and when treating are difficult to achieve favorable outcomes. This study characterizes outcomes associated with the use of cephalomedullary nails for fixation of Pauwels type-3 vertical femoral neck undisplaced-incomplete insufficiency fractures. Four consecutive patients with a Pauwels type-3 vertical femoral neck tensile insufficiency fracture from 2016 to 2018 were reviewed. Magnetic resonance imaging data revealed tensile visible fracture lines and hip-joint effusions with a high shear angle. For all patients, bone mineral density and vitamin D levels were low; vitamin D therapy was initiated immediately. Surgical procedures were conducted with cephalomedullary nails (Gamma 3 locking nail system; Stryker) under general anesthesia. A cephalomedullary nail appears to be a safe and effective alternative to the use of multiple parallel screws or a sliding hip screw for fixation of vertical femoral neck stress fractures (level of evidence: Level V).

[Diagnostic imaging and classification of proximal femoral and tibia fractures in adults]

BACKGROUND

A confident diagnosis and classification of proximal femoral and tibia fractures are crucial to determine further therapeutic procedures.

MATERIALS AND METHODS

In this article the current standards regarding diagnostic imaging of proximal femoral and tibia fractures are presented and the different classification systems are discussed.

CONCLUSIONS

Plain radiography in two planes remains the initial investigation of choice for suspected osseous injury. While this is usually sufficient to determine further procedures for injuries of the proximal femur, cross-sectional imaging is normally necessary in the diagnosis of proximal tibia fractures.

Improving the Diagnosis of Ipsilateral Femoral Neck and Shaft Fractures: A New Imaging Protocol

BACKGROUND

Despite increased awareness of ipsilateral femoral neck fractures in patients with high-energy femoral shaft fractures and advanced imaging with thin-cut high-resolution computed tomography (CT), failure of diagnosis remains problematic. The purpose of the present study was to determine if the preoperative diagnosis of ipsilateral femoral neck fractures in patients with high-energy femoral shaft fractures can be improved with magnetic resonance imaging (MRI) compared with radiographic and CT imaging.

METHODS

In response to delayed diagnoses of femoral neck fractures despite thin-cut high-resolution CT, our institutional imaging protocol for acute, high-energy femoral shaft fractures was altered to include rapid limited-sequence MRI to evaluate for occult femoral neck fractures. All patients received standard radiographic imaging as well as thin-cut high-resolution pelvic CT imaging upon presentation. Rapid limited-sequence MRI of the pelvis was obtained to evaluate for an occult femoral neck fracture.

RESULTS

Thirty-seven consecutive patients with 39 acute, high-energy femoral shaft fractures resulting from blunt trauma were included. The average age of the patients was 29.1 years (range, 14 to 82 years). Ten (25.6%) of the 39 femoral shaft fractures were open. Two femoral shaft fractures (5.1%) were associated with ipsilateral femoral neck fractures that were detected on radiographs, and no MRI was performed. None of the remaining 37 femoral shaft fractures were associated with a femoral neck fracture that was identified on CT imaging. Thirty-three (89.2%) of 37 patients underwent pelvic MRI to evaluate the ipsilateral femoral neck. Four (12.1%) of those 33 patients were diagnosed with a femoral neck fracture (2 complete, 2 incomplete) that was not identified on thin-cut high-resolution CT or radiographic imaging.

CONCLUSIONS

Rapid limited-sequence MRI of the pelvis for patients with femoral shaft fractures identified femoral neck fractures that were not diagnosed on thin-cut high-resolution CT in 12% of our patients. Our results suggest that the frequency of femoral neck fractures may be underrepresented on CT imaging; rapid limited-sequence MRI was feasible without delaying definitive treatment even in polytraumatized patients.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Long-term follow-up outcomes for patients undergoing primary total hip arthroplasty with uncemented versus cemented femoral components: a retrospective observational study with a 5-year minimum follow-up

BACKGROUND

This retrospective analysis compared the long-term outcomes for patients with a femoral neck fracture (AO/OTA type 31B) treated with a primary unilateral total hip arthroplasty with uncemented or cemented femoral components (UTHA or CTHA, respectively).

METHODS

We conducted a retrospective cohort study using the South China Hip Arthroplasty Database. We identified 422 patients with femoral neck fracture (AO/OTA type 31B) who were previously treated with primary unilateral UTHA or CTHA between 2007 and 2015, with follow-up until 2019. Follow-up occurred 1, 3, 6 and 12 months postoperatively and yearly thereafter. The primary outcome was the Harris hip score (HHS). The secondary outcome was the orthopaedic complication rate.

RESULTS

In total, 324 patients (UTHA n = 160, mean age 68.61 ± 7.49 years; CTHA n = 164, mean age 68.75 ± 7.04 years) were evaluated for study eligibility. The median follow-up was 73.3 months (range, 11.6-89.2 months). At the final follow-up, HHS was 74.09 ± 6.23 vs 79.01 ± 10.21 (UTHA vs CTHA, p = 0.012). Significant differences were detected in the incidence of prosthetic revision, loosening, and periprosthetic fracture between the UTHA and CTHA groups (7.5% for UTHA vs 1.8% for CTHA, p = 0.015; 17.5% for UTHA vs 8.5% for CTHA, p = 0.016; 11.9% for UTHA vs 4.9% for CTHA, p = 0.021, respectively).

CONCLUSION

In this setting, CTHA demonstrated superiority to UTHA by improving functional outcomes and decreasing complication rates.

Bilateral spontaneous simultaneous femoral neck occult fracture in a middle-aged man due to osteoporosis and vitamin D deficiency osteomalacia: A case report and literature review

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Physicians should take spontaneous femoral neck occult fracture into consideration if they report groin pain or difficulty in walking, even when findings from plain X-ray are normal.

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In a patient with spontaneous femoral neck occult fracture, diagnosing and treating the underlying etiology of osteoporosis and osteomalacia are essential for improving prognosis.

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This is the first report of a case of bilateral spontaneous simultaneous occult fracture of the femoral neck caused by osteoporosis and osteomalacia in a middle aged man.

Introduction

Bilateral stress fracture of the femoral neck is very rarely seen in healthy young patients who are neither athletes nor military recruits.

Presentation of case

The present report describes a 51-year-old male patient, not an athlete and with no previous history of disease, who developed bilateral stress fracture of the femoral neck without displacement.

Discussion

Simultaneous bilateral femoral neck fracture is a rare injury. In the present case, two factors predisposed to bilateral occult fracture of the femoral neck. The first was osteoporosis due to the patient’s smoking and alcohol abuse. The second was vitamin D deficiency osteomalacia associated with inadequate sun exposure.

Conclusion

All patients who present with spontaneous hip pain should be evaluated for osteoporosis and osteomalacia and assessed for underlying occult fracture if they report groin pain or difficulty in walking, even when findings from plain X-ray are normal, to improve prognosis in this rare and serious condition.