Femoral neck stress fractures and metabolic bone disease

Unusual Presentation of Hip Pain in a Pregnant Woman Due to Bilateral Cervical Neck Stress Fractures: A Case Report

CASE

We present an unusual case of bilateral femoral neck fatigue fractures in a 28-year-old pregnant woman at the 18th week of gestation successfully treated through operative intervention involving consecutive total hip arthroplasty and internal fixation within the same procedure, resulting in favorable clinical outcomes.

CONCLUSION

Current clinical practices suggest that a restricted use of plain radiographs, even those involving the pelvis in pregnant women carries a minimal risk to the fetus and is not contraindicated. Magnetic resonance imaging proved valuable for differential diagnosis, contrasting with sonography.

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.

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

➤

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

➤

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

➤

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

➤

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

➤

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

➤

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

Femoral Neck Stress Fractures: MRI Risk Factors for Progression

BACKGROUND

Femoral neck stress fractures are overuse injuries with devastating consequences if not diagnosed and treated appropriately. The aim of this study was to retrospectively review femoral neck stress fractures using a magnetic resonance imaging (MRI)-based protocol and to identify imaging risk factors that could predict fracture progression requiring surgical intervention.

METHODS

We identified all femoral neck stress fractures treated at our institution from 2002 to 2015. Inclusion criteria for the study were unilateral pathology involving either an incomplete femoral neck stress fracture with a visualized fracture line or edema without a distinct fracture line. MRI data were evaluated for edema, fracture line percentage, and hip effusion. A surgical procedure was offered to patients with fractures with interval progression on serial MRI after 6 weeks of nonoperative treatment.

RESULTS

We identified 305 patients who met inclusion criteria. Initial MRI showed edema with a fracture line in 54.4% of patients and isolated edema in 45.6% of patients. Interval MRI was performed in 194 patients at a mean time of 6 weeks, and it revealed fracture progression in 13.9% of patients. There were no significant differences in the size of the fracture line on initial MRI between the group who progressed to a surgical procedure and those who resolved with nonoperative treatment (mean [and standard deviation], 24.6% ± 8.1% [95% confidence interval (CI), 21.4% to 27.8%] and 25.5% ± 11.1% [95% CI, 22.9% to 28.1%]; p = 0.287). Of the patients who required a surgical procedure, 85.2% had an effusion on the initial MRI compared with only 26.3% of those who showed interval resolution with nonoperative treatment. Those who had a hip effusion on the initial MRI had 8 times (relative risk, 8.02 [95% CI, 2.99 to 21.5]; p < 0.0001) the risk of fracture progression to surgical fixation compared with those without a hip effusion.

CONCLUSIONS

In patients with a femoral neck stress fracture and fracture line, the presence of a hip effusion on the initial MRI screening is an independent risk factor for fracture progression and early prophylactic surgical intervention should be considered. All patients with isolated edema in the femoral neck without a fracture line on the initial MRI had resolution with nonoperative treatment and did not have fracture progression toward surgical fixation.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Gaps and opportunities in the management of the young femoral neck fracture

Femoral neck fractures in young adults are difficult to treat. There are substantial gaps in our knowledge regarding treatment and prevention of young adult femoral neck fractures. Avoiding malunion or nonunion of these fractures after fixation remains a challenge. Currently available fixation techniques may allow for healing to occur, but in a shortened position, with negative consequences on gait mechanics and physical function. Osteonecrosis remains a problem, affecting up to half of patients who sustain femoral neck fractures. Achieving reliable healing may require a reconsideration of fracture fixation implants as well as biological methods to address metabolic, endocrine, and/or genetic abnormalities that may be present in the young adult femoral neck fracture patient. Also, prevention of low-energy femoral neck fractures (e.g. stress fracture) remains an area ripe for investigation.

Does cam osteochondroplasty compromise proximal femur strength?

Little is known about the effect on load bearing ability of cam-type femurs following osteochondroplasty. The aim of this study was to compare the change in deformation undergone by cam-type femoral acetabular impingement femur models after resection of different volumes. Dry-bone replicas (N = 10) of two cam-type femurs (cam A and B) underwent resections of increasing volume (Surgery I, II and III) representing conservative, adequate and radical resections. Deformation under cyclic loading of 700 N for five cycles after each surgery was compared. The 360° alpha angle and the change in head to neck ratio at four equidistant points along the femoral neck were used as measures of surgical efficacy and volume resected. Intact cam A and B replicas had a maximum alpha angle of 88° and 90°, respectively, which were reduced to 55° and 54° post Surgery I. Cam A replicas showed a significant reduction (p < 0.01) in mean axial displacement after Surgery I (up to 10% reduction in neck volume) and an increase after Surgery III (~20%-40% reduction in neck volume) compared to unresected controls (p < 0.01). Surgery II (~10%-15% reduction in neck volume) produced no significant change in mean displacement (p > 0.05). Cam B models exhibited lower mean displacement after Surgery I, II and III (p < 0.01) compared to unresected controls. Conservative surgery appears to improve the axial load bearing ability of dry-bone models. Radical resections may significantly decrease the fracture-resistant properties of bone following osteochondroplasty which should be noted when planning such a procedure.

Acetabular retroversion in military recruits with femoral neck stress fractures

Acetabular retroversion (AR) alters load distribution across the hip and is more prevalent in pathologic conditions involving the hip. We hypothesized the abnormal orientation and mechanical changes may predispose certain individuals to stress injuries of the femoral neck. We retrospectively reviewed the anteroposterior (AP) pelvic radiographs of 54 patients (108 hips) treated for a femoral neck stress fracture (FNSF) and compared these radiographs with those for a control group of patients with normal pelvic radiographs. We determined presence of a crossover sign (COS), femoral neck abnormalities, and neck shaft angle. The prevalence of a positive COS was greater in patients with stress fractures than in the control subjects (31 of 54 [57%] versus 17 of 54 [31%], respectively) and higher than for control subjects reported in the literature. Thirteen patients had radiographic changes of the femoral neck consistent with femoroacetabular impingement (FAI). These radiographic abnormalities were seen more commonly in retroverted hips. A greater incidence of AR was noted in patients with FNSF. Potential implications include more aggressive screening of military recruits with AR and the new onset of hip pain. Finally, we present an algorithm we use to diagnose and treat these relatively rare FNSFs.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Stress Fracture of the Femoral Neck in a Young Female Athlete

Stress fractures have been reported to occur in association with running. They typically involve the lower extremity. Although relatively rare, unrecognized or untreated femoral neck fractures carry a much higher morbidity rate than other stress fractures. Stress fractures of the femoral neck should even be considered in young amateur athletes with hip pain. If X-ray is inconclusive, radionuclide bone imaging and MRI can be useful in diagnosing these fractures. This rare diagnosis, as well as classification and treatment options, will be discussed.