Femoral neck stress fractures in military personnel--a case series

Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis

OBJECTIVE

Bone stress injuries (BSIs) are classified in clinical practice as being at low- or high-risk for complication based on the injury location. However, this dichotomous approach has not been sufficiently validated. The purpose of this systematic review was to examine the prognostic role of injury location on return-to-sport (RTS) and treatment complications after BSI of the lower extremity and pelvis.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Web of Science, Cochrane CENTRAL and Google Scholar databases were searched from database inception to December 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Peer-reviewed studies that reported site-specific RTS of BSIs in athletes.

RESULTS

Seventy-six studies reporting on 2974 BSIs were included. Sixteen studies compared multiple injury sites, and most of these studies (n=11) described the anatomical site of injury as being prognostic for RTS or the rate of treatment complication. Pooled data revealed the longest time to RTS for BSIs of the tarsal navicular (127 days; 95% CI 102 to 151 days) and femoral neck (107 days; 95% CI 79 to 135 days) and shortest duration of time for BSIs of the posteromedial tibial shaft (44 days, 95% CI 27 to 61 days) and fibula (56 days; 95% CI 13 to 100 days). Overall, more than 90% of athletes successfully returned to sport. Treatment complication rate was highest in BSIs of the femoral neck, tarsal navicular, anterior tibial shaft and fifth metatarsal; and lowest in the fibula, pubic bone and posteromedial tibial shaft.

CONCLUSION

This systematic review supports that the anatomical site of BSIs influences RTS timelines and the risk of complication. BSIs of the femoral neck, anterior tibial shaft and tarsal navicular are associated with increased rates of complications and more challenging RTS.

PROSPERO REGISTRATION NUMBER

CRD42021232351.

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.

Part I: Background and Clinical Considerations for Stress Fractures in Female Military Recruits

INTRODUCTION

Stress fractures (SFx) represent a significant proportion of musculoskeletal injuries in military recruits internationally. Incidence rates as high as 40% have been reported, varying by country and branch of military cohorts. Tibial SFx are the most common, followed by other lower extremity sites, and are related to the emphasis on running during training. SFx disproportionately affect female recruits, similarly to a disparity demonstrated in female athletes.

METHODS

A literature review of articles relevant to our review was conducted using PubMed, utilizing keywords stress fracture, military, recruits, diagnosis, management, treatment, prevention, epidemiology, background, and/or female. Articles older than 10 years old (prior to 2010) were not considered. Review articles were considered, but if a research article was cited by a review, the research was included directly. Articles with primary military data, members of the military as subjects, especially when female recruits were included, were strongly considered for inclusion in this review.

RESULTS

SFx can cause medical morbidity and financial burden and can require discharge from military service. SFx management in the military has cost the United States approximately $100 million annually, which may be underestimated due to lost duty hours or medical discharge with resulting compensation. However, SFx incidence rates have been demonstrated to be reducible with concerted efforts in military cohorts.

CONCLUSION

This review, Part I of a two-part series, provides updated information for multidisciplinary management of SFx in female military recruits. There are many similarities to management in athletes, but unique nuances of the military recruit require specific knowledge to reduce the high incidence rates of injury.

[Femoral neck stress fractures and femoroacetabular impingement : A retrospective case study and literature review]

BACKGROUND

Femoroacetabular impingement (FAI) can lead to morphologic damage of both the acetabulum and the femoral neck. Recent reports have found an association between impingement deformities and the development of femoral neck stress fractures. The aim of this study was to report a series of patients with these findings and to update the current evidence on the topic.

MATERIAL AND METHODS

5 patients (6 cases) with atraumatic femoral neck fractures and FAI were identified in the Dresden hip registry from 2015 to 2018. Demographic data, comorbidities, radiographic results and bone metabolism results were described. A literature search was conducted using keywords related to femoral neck stress fractures and FAI syndrome.

RESULTS

The average age of the series was 39 (range: 22-52), 2 patients were female and 3 male. A total of 12 surgical procedures were performed. 4 of the 5 patients showed radiographic features of pincer and/or cam-FAI, whereas 3 patients had a decreased femoral antetorsion (-7° to +7° antetorsion). In 3 patients, magnetic resonance imaging revealed additional signs of avascular necrosis ARCO I. There was a lack of FAI-specific treatment recommendations in the available literature.

DISCUSSION

Radiographic results of the patients evaluated suggested that impingement-associated deformities of the hip may cause femoral neck stress fractures, which is in line with the available literature. This potential coincidence should be integrated in diagnostic algorithms and therapeutic approaches.

Stress fractures in military recruits: A prospective study for evaluation of incidence, patterns of injury and invalidments out of service

Background

Stress fractures (SFs) occur because of repetitive submaximal stresses to the bone over a period of time. SFs cause an economic loss to the organization and to the individuals who get invalided out of army because of SFs. This study was conducted to determine the incidence, distribution, onset of SFs, and invalidment patterns due to SFs.

Methods

This prospective study was carried out among recruits undergoing training at training centres in a cantonment of Central India. The recruits enrolled were followed up through their training period for occurrence of SF. On occurrence of SF, the clinical features, site of bone involved, and the weeks of completed military training were noted. The SFs were graded into four grades based on clinicoradiological features and managed accordingly.

Results

A total of 8974 recruits were enrolled into the study, of which 208 recruits suffered SFs. The commonest bone involved was the tibia (86.5%), commonest site being the proximal one-third of the tibia shaft (46.2%). Average week of developing SF was the 15th week of training. Seven recruits were invalided out of army because of SFs, the commonest cause being femoral neck SFs.

Conclusion

Prevention is the best approach for SFs. It is suggested to increase the intensity of training gradually over the first 16 weeks and recruits are to be given a training pause at around the 12th week for healing of stressed bones just before the peak time of occurrence of SFs. Femoral neck SFs are the commonest SFs responsible for invalidment of recruits.

Outcome of surgical management of stress fractures in high demand individuals

Stress fractures represent one-fifth of overuse injuries in sport. Successful healing of stress fractures in high demand individuals is important to prevent complications upon early return to activity. This article reviews the literature on outcomes of surgical management of stress fractures in high demand individuals. An online literature search was carried out for articles published up to and including January 2017. Twenty five papers were reviewed. In the majority of studies, no complications were reported, clinical and radiographic healing was achieved, and patients returned to their premorbid level of activity. Current literature suggests good outcomes after surgical management of stress fractures in high demand individuals, particularly those in whom conservative treatment has failed. Further studies comparing surgical techniques are necessary to demonstrate the most efficacious.

Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature

Femoral neck stress fractures (FNSFs) in healthy young subjects are uncommon and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders followed by amenorrhea and osteoporosis. This case report describes four young and middle-aged, active female recreational runners who developed stress fractures of the femoral neck. In three of them, with a clinical history of persistent pain in the groin region, which worsened during training, early diagnosis by MRI was considered essential in detecting the fractures. The patients were clinically, metabolically and radiographically evaluated; they were then treated and followed-up at our institution. Only one case was treated conservatively, while the others underwent surgical internal fixation using a screw-plate (DHS®). All of them returned to sport physical activity after a recovery period. Regarding the challenging management of FNSFs, our report highlights the importance of groin pain, especially in athletic females, an early diagnosis by MRI, and a proper classification of these injuries for a correct choice of treatment in order to prevent further dislocation and avoid avascular necrosis of the femoral head. (www.actabiomedica.it)

Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature

Femoral neck stress fractures (FNSFs) in healthy young subjects are uncommon and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders followed by amenorrhea and osteoporosis. This case report describes four young and middle-aged, active female recreational runners who developed stress fractures of the femoral neck. In three of them, with a clinical history of persistent pain in the groin region, which worsened during training, early diagnosis by MRI was considered essential in detecting the fractures. The patients were clinically, metabolically and radiographically evaluated; they were then treated and followed-up at our institution. Only one case was treated conservatively, while the others underwent surgical internal fixation using a screw-plate (DHS®). All of them returned to sport physical activity after a recovery period. Regarding the challenging management of FNSFs, our report highlights the importance of groin pain, especially in athletic females, an early diagnosis by MRI, and a proper classification of these injuries for a correct choice of treatment in order to prevent further dislocation and avoid avascular necrosis of the femoral head.

Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature

Femoral neck stress fractures (FNSFs) in healthy young subjects are uncommon and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders followed by amenorrhea and osteoporosis. This case report describes four young and middle-aged, active female recreational runners who developed stress fractures of the femoral neck. In three of them, with a clinical history of persistent pain in the groin region, which worsened during training, early diagnosis by MRI was considered essential in detecting the fractures. The patients were clinically, metabolically and radiographically evaluated; they were then treated and followed-up at our institution. Only one case was treated conservatively, while the others underwent surgical internal fixation using a screw-plate (DHS®). All of them returned to sport physical activity after a recovery period. Regarding the challenging management of FNSFs, our report highlights the importance of groin pain, especially in athletic females, an early diagnosis by MRI, and a proper classification of these injuries for a correct choice of treatment in order to prevent further dislocation and avoid avascular necrosis of the femoral head.

Functional Outcomes Following Surgical Management of Femoral Neck Stress Fractures

The Military Health System Management Analysis and Reporting Tool was queried to identify all active duty US military service members who underwent operative fixation of femoral neck stress fractures from 2011 to 2012. A total of 13 patients with 17 femoral neck stress fractures met the inclusion criteria. Average patient age was 23.8±5.1 years, and 62% were women. At a mean 26-month follow-up, approximately one-half (46%) of the young military recruits were able to return to their preoperative activity level. Two (11%) required reoperation. Increased time to diagnosis and to subsequent fixation was associated with a greater risk of poor outcomes resulting in medical separation. [Orthopedics. 2017; 40(3):e395-e399.].

Bilateral stress fracture of femoral neck in non-athlete - case report

Bilateral stress fracture of femoral neck in healthy young patients is an extremely rare entity, whose diagnostic and treatment represent a major challenge. Patients with history of hip pain, even non-athletes or military recruits, should be analyzed to achieve an early diagnosis and prevent possible complications from the surgical treatment. This report describes a 43-year-old male patient, non-athlete, without previous diseases, who developed bilateral stress fracture of femoral neck without displacement. He had a late diagnosis; bilateral osteosynthesis was made using cannulated screws. Although the diagnosis was delayed in this case, the study highlights the importance of the diagnosis of stress fracture, regardless of the activity level of the patients, for the success of the treatment.

Young man with sudden severe hip pain secondary to femoral neck stress fracture

Femoral neck stress fractures have been described in military recruits and athletes. Early recognition and aggressive treatment are important, as femoral neck stress fractures have a high potential for complications and even uncomplicated fractures require an extensive course of rehabilitation. Tension-side (superolateral) stress fractures of the femoral neck are at high risk for complications such as displacement, non-union and avascular necrosis, and need to be treated surgically, while compression-side (inferomedial) fractures can be treated conservatively. We describe a case illustrating a typical presentation of insidious hip pain culminating in sudden onset of severe hip pain in a healthy young man. We perform a literature review of studies showing epidemiology, treatment algorithms and rehabilitation.

Osteoid Osteoma of the Femoral Neck in Athletes: Two Case Reports Differentiating From Femoral Neck Stress Injuries

The diagnosis of an intra-articular osteoid osteoma can be a challenging and lengthy process, with reports of delayed diagnosis of greater than 2 years. In the young, athletic patient with an atraumatic onset of groin pain, an overuse injury or muscle strain is the most likely etiology. However, an overuse injury of femoral neck stress fracture must be identified because of the potentially disastrous outcome of fracture completion. The similar clinical presentation of a femoral neck stress fracture and intra-articular osteoid osteoma of the femoral neck can further delay the diagnosis of the osteoid osteoma. In a patient with these differential diagnoses that do not improve with a period of nonweightbearing activity, a more intensive workup must ensue. The purpose of this case report is to describe the initial presentations, subsequent follow-up, and imaging findings leading to the diagnosis of osteoid osteoma as well as to differentiate an osteoid osteoma from femoral neck stress injuries.

Bilateral femoral neck stress fractures in military recruits with unilateral hip pain

Femoral neck stress fractures are rare and can be easily missed and failure to diagnose these injuries early can lead to avascular necrosis, malunion and osteoarthritis. It is important to have a high index of suspicion for femoral neck stress fractures in military recruits. We present three cases of bilateral femoral neck fractures in military recruits, all presenting with unilateral hip symptoms and signs. All the asymptomatic contralateral hips had femoral neck stress fractures diagnosed by screening MRI. Tension type and displaced femoral neck fractures were treated surgically. All the fractures managed healing without complications. Military recruits with unilateral groin pain should have an early referral for MRI hip to rule out femoral neck stress fractures and those military personnel with ipsilateral femoral neck fracture should have MRI of the contralateral hip. Two of the patients had vitamin D deficiency, of which one had elevated parathyroid hormones and low bone mineral density. Our case series highlights the significance of vitamin D deficiency among military recruits.

Lower extremity stress fractures in the military

Stress fractures of the lower extremities are common among the military population and, more specifically, military recruits who partake in basic training. Both intrinsic and extrinsic factors play a role in the development of these injuries, and it is important to identify those individuals at risk early in their military careers. Some of these factors are modifiable, so they may become preventable injuries. It is important to reiterate that one stress fracture places the soldier at risk for future stress fractures; but the first injury should not be reason enough for separation from the military, as literature would support no long-term deficits from properly treated stress fractures. Early in the process, radiographic analysis is typically normal; continued pain may warrant advanced imaging, such as scintigraphy or MRI. Most stress fractures that are caught early are amendable to nonoperative management consisting of a period of immobilization and NWB followed by progressive rehabilitation to preinjury levels. Complete or displaced fractures may require operative intervention as do tension-sided FNSF. Improving dietary and preaccession physical fitness levels may play a role in reducing the incidence of stress fractures in the active-duty military population. It is important to keep in mind when evaluating soldiers and athletes who present with activity-related pain that stress fractures are not uncommon and should be given significant consideration.

A case report of missed femoral neck stress fracture

Femoral neck stress fracture (FNSF) is an uncommon but potentially serious orthopaedic problem. This is a case report on missed femoral neck stress fracture in a 62-year-old female who was initially treated as early-onset coxarthrosis. She later presented to us with a displaced intra-capsular neck of left femur fracture and underwent total hip replacement. This case illustrates that causes other than osteoarthritis should be taken into consideration in patients presenting with anterior hip pain where symptoms are disproportionate to clinical and radiological findings. More advanced investigations such as MRI scan or regular follow up with plain radiographs should be performed. A delay in diagnosis can lead to secondary displacement of the femoral neck stress fracture.

Incidence and Time to Return to Training for Stress Fractures during Military Basic Training

Currently, little is known about the length of time required to rehabilitate patients from stress fractures and their return to preinjury level of physical activity. Previous studies have looked at the return to sport in athletes, in a general population, where rehabilitation is not as controlled as within a captive military population. In this study, a longitudinal prospective epidemiological database was assessed to determine the incidence of stress fractures and the time taken to rehabilitate recruits to preinjury stage of training. Findings demonstrated a background prevalence of 5% stress fractures in Royal Marine training; femoral and tibial stress fractures take 21.1 weeks to return to training with metatarsal stress fractures being the most common injury taking 12.2 weeks. Rehabilitation from stress fractures accounts for 814 weeks of recruit rehabilitation time per annum. Stress fracture incidence is still common in military training; despite this stress fracture recovery times remain constant and represent a significant interruption in training. It takes on average 5 weeks after exercise specific training has restarted to reenter training at a preinjury level, regardless of which bone has a stress fracture. Further research into their prevention, treatment, and rehabilitation is required to help reduce these burdens.

Femoral and tibial stress fractures associated with vitamin D insufficiency

We describe a case highlighting the need to consider hypovitaminosis-D when investigating background causation and treatment of femoral and tibial stress fractures. The case also suggests that prescribing calcium and vitamin D supplementation may help with fracture healing in soldiers presenting with stress fractures who may have unrecognised hypovitaminosis-D which if left untreated may delay fracture healing.

Unusual presentation of a femoral stress fracture

Stress fractures are common injuries in sports medicine. Among these fractures, femoral neck stress fractures frequently have a benign course, especially when it happens in the medial aspect of the neck. This case report describes a stress fracture of the medial aspect of the femoral neck that developed a complete fracture and underwent surgical fixation.

Displaced stress fracture of the femoral neck in young active adults

Stress fractures of the femoral neck in healthy individuals are rare and most prevalent among long-distance runners and military recruits. Women seem to be at higher risk of developing stress fractures because of possible eating disorders and, thereby, following amenorrhoea and osteoporosis. The majority of fractures of the femoral neck are undisplaced. However, they might progress into displaced fractures with avascular necrosis of the femoral head and following development of osteoarthritis as a probable consequence even when treated properly. Early diagnosis with MRI or radionuclide scanning in patients with a history of pain in the groin region during training might be crucial in detecting the fractures at early stages; thereby preventing possible complications following surgical treatment of displaced fractures. The authors present a report of two young adults who developed displaced fractures of the femoral neck and were treated with closed reduction and internal fixation.