Stress fractures of the hip in Royal Marine recruits under training: a retrospective analysis

Suggestion of a Novel Classification Based on the Anatomical Region and Type of Bilateral Fatigue Femoral Fractures

Purpose: Bilateral fatigue femoral fractures (BFFF) represent an extremely rare clinical entity. The present study introduces a novel classification, in order to categorize the BFFFs and provide a thorough review of all these, so far in the literature, reported cases. Methods: The BFFF were classified taking into account the anatomical region of the femoral fracture; (fh): femoral head, (sc): sub-capital, (pt): peri-trochanteric, (st): sub-trochanteric, (s): shaft, (d): distal femur and the fracture type (complete or incomplete); type I: bilateral incomplete fractures, type II: unilateral incomplete fracture, and type III: bilateral complete fractures. Type III was further subdivided into type IIIA: bilateral non-displaced fractures, type IIIB: unilateral displaced fracture, and type IIIC: bilateral displaced fractures. Furthermore, a meticulous review of the PubMed and MEDLINE databases was conducted to locate all articles reporting these injuries. Results: A total of 38 patients (86.8% males), with a mean age of 25.3 years, suffering BFFFs were identified from the literature search. The mean time interval from symptoms' onset to diagnosis was 54 days. According to the proposed classification, 2.6% of the fractures were categorized as type I (h), 36.8% as type I (sc), 2.6% as type I(st/s), 7.9% as type I (s), 2.6% as type I (d), 5.4% as type II (fh), 26.3% as type II (sc), 2.6% as type IIIA (st), 2.6% as type IIIA (d), 5.4% as type IIIB (sc), 2.6% as type IIIB (d) and 2.6% as type IIIC (sc). Surgery was performed in 52.6%, while non-operative treatment was followed in 47.4% of the population. Regarding the fracture type, 75% of type I fractures were conservatively treated, while 91.7% and 66.6% of type II and III fractures were surgically treated. For patients treated conservatively, the mean time from diagnosis to return to previous status was 260 days, while for patients treated surgically, 343 days. Conclusions: BFFFs, although rare, may pose a diagnostic and therapeutic challenge. The present classification offers valuable information and may act as a guide for the management of these patients.

Femoral Neck Stress Fracture: Can MRI Grade Help Predict Return-to-Running Time?

BACKGROUND

Limited research is available regarding return-to-running (RTR) time after femoral neck stress fractures. While studies have shown the prognostic value of image-based grading scales for stress fractures at other sites, few have included femoral neck stress fractures.

PURPOSE

To determine if the grade of femoral neck stress fractures based on magnetic resonance imaging (MRI) characteristics correlates with RTR time.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This study included 24 patients (mean age, 32.9 years; range, 18-51 years) who were diagnosed with 27 femoral neck stress fractures by MRI from 2009 to 2015 at a single sports medicine clinic. All fractures were compression sided and were treated nonoperatively. Charts were reviewed for patient demographics and RTR time. Images were graded from 1 to 4 using the Arendt stress fracture severity scale. Statistical analysis was performed using survival analysis and Cox proportional hazard model to compare the RTR time between grades. Cox regression was repeated, adjusted for age, bone mineral density (BMD), and body mass index (BMI).

RESULTS

The mean (±standard error of the mean) RTR time in weeks for patients with fractures graded 1 to 4 was 7.4 ± 2.7 (range, 4-11), 13.8 ± 3.8 (range, 6-21), 14.7 ± 3.5 (range, 8.5-24), and 17.5 ± 3.4 (range, 10-32), respectively. Survival analysis indicated that there was a statistically significant effect of fracture grade on RTR time (P = .0065). The Cox model indicated a statistically significant difference in RTR time between grades 1 and 2 (P = .036), 1 and 3 (P = .014), and 1 and 4 (P = .002). The unadjusted hazard ratio was significant (P = .037). There were no statistically significant differences between the remaining grades (P = .82 for grades 2 and 3, P = .37 for grades 2 and 4, and P = .31 for grades 3 and 4). Age (P = .71) and BMD (P = .81) did not have an effect on RTR time. The hazard ratio remained significant (P = .05) after adjusting for age and BMD. BMI tended to have an effect on RTR time (P = .09). After adding BMI to the adjustment, the hazard ratio decreased in significance (P = .13), although sample size also decreased.

CONCLUSION

Grade 2 to 4 femoral neck stress fractures require longer RTR time than do grade 1 injuries. Patients with lower BMI tend to require a longer RTR time.

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.

Modified valgus osteotomy of the femoral neck for late presenting femoral neck stress fractures in military recruits

Neglected or late presenting femoral neck stress fractures are often associated with varus deformity, with potential risks of nonunion and osteonecrosis. We proposed a surgical technique whereby a wedge osteotomy was performed at the basal part of the neck, on the tensile surface, keeping the inferomedial femoral neck as a hinge. The femoral shaft was abducted to close the osteotomy site and it was fixed with three cannulated cancellous screws. Three military recruits who presented with neglected femoral neck stress fracture with varus deformity were operated on with the proposed modified femoral neck valgus osteotomy. All the fractures united without any complications and the patients resumed their professional activity.

Stress fracture

Stress fractures are common overuse type injuries, caused by repetitive stresses applied to bone leading to a change within the normal physiological balance and altering key structural properties. These injuries have been well documented within certain groups of the population, as well as related to certain activity types, and pose significant diagnostic and treatment challenges. Complication of stress fractures can vary dependant of the anatomical site and the prognosis of an injury can have wide ranging effects, dependant of lifestyle choices and occupation of the patient. This piece endeavours to outline the most current and evidentiary concepts pertaining to important aspects of stress fractures, from pathophysiology through to prognosis.

Bilateral femoral neck stress fractures in a fire academy student

Unilateral femoral neck stress fractures are well documented in active patients; however, the risk of a subsequent contralateral stress fracture remains unknown in patients who continue to be active. This article describes a 24-year-old male fire academy student who sustained a left femoral neck stress fracture, followed approximately 11 months later by a right femoral neck stress fracture, both of which went on to completely displace. A review of the index radiographs of each hip from outside institutions revealed femoral neck stress fractures that went undiagnosed until they displaced. The patient was referred to our institution and underwent closed reduction and internal fixation using cannulated screws in both cases. A full endocrine evaluation was performed in the following weeks and proved unremarkable. Although it is difficult to extrapolate the results from 1 patient beyond the case studied, there is cause for concern in patients who remain active following femoral neck stress fractures. Our case highlights the significance of obtaining a complete and thorough medical history on physical examination and appropriately counseling patients regarding activity level. Until further research explores this possible relationship, physicians evaluating patients with a history of a stress fracture are encouraged to be vigilant of subsequent contralateral fractures and educate patients of this potentially avoidable injury.

Hip resurfacing increases bone strains associated with short-term femoral neck fracture

Short-term femoral neck fracture is a primary complication associated with contemporary hip resurfacing. Some fractures are associated with neck notching, while others occur in the absence of notching. These unexplained fractures may be due to large magnitude strains near the implant rim, which could cause bone damage accumulation and eventual neck fracture. We used statistically augmented finite element analysis to identify design and environmental variables that increase bone strains near the implant rim after resurfacing, and lead to strain magnitudes sufficient for rapid damage accumulation. After resurfacing, the compressive strains in the inferior, peripheral neck increased by approximately 25%, particularly when the implant shell was bonded. While the tensile strains in the peripheral neck were low in magnitude in the immediate postoperative models, they increased substantially following compressive damage accumulation. Low bone modulus, within the range of normal bone, and high head load contributed the most to large magnitude strains. Therefore, in some cases, hip resurfacing may cause a region of compressive bone damage to develop rapidly, which in turn leads to large tensile strains and potential neck fracture. Our study suggests that indications for surgery should account for bone material quality, and that rehabilitation protocols should avoid high-load activities.

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

Femoral neck stress fractures (FNSF) are uncommon, representing 5% of all stress fractures. In military personnel, FNSF represents one of the more severe complications of training, which can result in medical discharge. Clinical examination findings are often non-specific and plain radiography may be inconclusive--leading to missed or late diagnosis of FNSF This paper highlights the significance of FNSFs in military personnel and alerts physicians to the potential diagnosis. We identified all military recruits, aged 17 to 26, who attended the Infantry Training Centre (Catterick, U.K.), over a four-year period from the 1st July 2002 to 30th June 2006, who had suffered a FNSF. The medical records, plain radiographs, bone scans and MRIs of the recruits were retrospectively reviewed. Of 250 stress fractures 20 were of the femoral neck; representing 8% of all stress fractures and an overall FNSF rate of 12 in 10,000 military recruits. FNSFs were most prevalent amongst Parachute Regiment recruits (1 in 250, p < 0.05). Onset of symptoms was most commonly between weeks 13-16 of training. The majority (17/20, 85%) of FNSFs were undisplaced, these were all treated conservatively. Three FNSFs were displaced on presentation and were treated surgically. Overall, the medical discharge rate was 40% (8/20). FNSFs are uncommon and the diagnosis remains a challenge to clinicians and requires a high index of suspicion in these young athletic individuals. In such individuals early referral for MRI is recommended, to aid prompt diagnosis and treatment and to prevent more serious sequelae.

A pathological fracture of the femoral neck associated with osteonecrosis of the femoral head and a stress fracture of the contralateral femoral neck

A pathological fracture of the right femoral neck associated with osteonecrosis of the right femoral head and a stress fracture of the contralateral femoral neck occurred in a 47-year-old man. Osteonecrosis was noted in almost the entire femoral head, and the pathological fracture occurred at the subcapital area. Six months later, a stress fracture was detected in the contralateral femoral neck. The stress fracture of the left femoral neck might have been caused by the incremental repetitive mechanical loading in the left hip as a result of the pathological fracture in the right hip. Therefore, it might be necessary to conduct a careful examination, using either a magnetic resonance imaging scan or a bone scan, of patients with extensive osteonecrosis of the femoral head because of the risk of osteonecrosis in the contralateral femoral head as well stress fractures in the contralateral femoral neck.

Stress fractures of the femoral neck

Stress fractures of the femoral neck are uncommon injuries. In general these injuries are seen in two distinct populations: (1) young, healthy, active individuals such as recreational runners, endurance athletes, or military recruits; and (2) the elderly who have osteoporosis. Stress fractures can be classified as either fatigue or insufficiency fractures and result from untoward cyclic loading or impaired bone quality. The key to treatment is early diagnosis, which may require scintigraphy or magnetic resonance imaging. Nondisplaced compression type stress fractures can be treated nonoperatively with protected weight-bearing and frequent radiographic followup. Tension type stress fractures should be stabilized internally to prevent the adverse consequences of fracture displacement.