Femoral Neck Stress Fractures in Military Personnel – A Case Series

Abstract

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.

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

“…The onset of fractures after increases in training (such as occurring with military recruit training) has been variably described at 4–5,10 4–711 up to 13–16 weeks,6 and also with even distribution throughout training 1 3 5 11 12. The sudden return to normal training load after hiatus for elective surgery is the presumed aetiological factor in the case of our patient.…”

“…In a study of 220 stress fractures in military recruits, femoral stress fractures healed the slowest, needing a mean time of 21.1 weeks for rehabilitation 1. Femoral neck stress fractures have been shown to result in medical military discharge in 40% of cases 6. These fractures are also associated with significantly increased medical costs.…”

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

“…In our series, the patients presented within 2 weeks after enlistment and femoral neck stress fracture has previously been reported to occur in recruits with 1 week to 7 months of military training 3 7. Newly enlisted servicemen have probably not been exposed to intensive physical training and upon enlistment there is an increase in high intensity physical training which can lead to the occurrence of bilateral femoral neck stress fractures.…”

Femoral and tibial stress fractures associated with vitamin D insufficiency

“…While the treatment of stress fractures is often straightforward, undetected stress fractures can lead to serious complications3 and also negatively affect military readiness 4. The prevalence of stress fractures in UK military personnel is 15 per 1000,5 but femoral stress fractures are relatively uncommon (12 per 10 000)5 and if left undiagnosed can lead to significant morbidity 5. Furthermore, the rate of femoral stress fracture is also dependent upon cap badge (attributed to the more strenuous training) with stress fracture rates for recruits in the Parachute regiment reported as 1 in 250 (40 per 10 000) compared with recruits in the Guards (1 in 1228) 5…”