Article Text
PDF
Abstract
Overuse injuries of the leg are a common problem for young soldiers. This article reviews the literature concerning the prevention and treatment of exercise related leg pain in military settings and presents the latest developments in proposed mechanisms and treatments. Current practice and treatment protocols from the Dutch Armed Forces are reviewed, with an emphasis on the most prevalent conditions of medial tibial stress syndrome and chronic exertional compartment syndrome. The conclusion is that exercise related leg pain in the military is an occupational problem that deserves further study.
- medial tibial stress syndrome
- chronic exertional compartment syndrome
- exercise related leg pain
- military
- review
- expert opinion
Statistics from Altmetric.com
- medial tibial stress syndrome
- chronic exertional compartment syndrome
- exercise related leg pain
- military
- review
- expert opinion
Key messages
Overuse injuries of the legs are a common problem in occupations that involve repetitive lower limb activities, such as the military.
The initial medical assessment before employment in the military provides the first opportunity to prevent exercise related leg pain (ERLP)
The most common diagnoses of young Dutch soldiers with ERLP are medial tibial stress syndrome (MTSS), chronic exertional compartment syndrome (CECS) and a combination of MTSS and CECS.
New elements in the conservative treatment of ERLP in a secondary care setting are extracorporeal shock wave treatment for MTSS and gait retraining for CECS.
Despite a growing body of knowledge, overuse injuries of the legs continue to have a high incidence, long recovery time and large impact on military training.
Introduction
A high prevalence of overuse injuries of the leg is reported in the military, especially in recruits and infantry soldiers.1–4 Young soldiers tend to develop complaints in the anterior leg, whereas older soldiers are more prone to develop overuse injuries in the posterior leg.5
There is a lack of longitudinal epidemiological data regarding leg injuries in the Dutch military, however, several cohort studies have shown that exercise related leg pain (ERLP) is one of the three most common overuse injuries that result in termination of a training course and that soldiers with ERLP remain longer in remedial platoons than those with other overuse injuries.6 ,7 A recent study among British recruits reconfirmed that medial tibial stress syndrome (MTSS) has a high incidence and a long rehabilitation time, making it the overuse injury with the greatest impact on military training.8
MTSS and chronic exertional compartment syndrome
MTSS and chronic exertional compartment syndrome (CECS) are the two most common types of ERLP of young soldiers in the Dutch military.7 In contrast to American and British military literature, stress fractures to the tibia are extremely rare in the Dutch armed forces and there is no clear explanation as to why.9 ,10 It is assumed that American and British recruits do more running, in shorter training courses, whereas Dutch recruits do more marching and their training courses are, on average, longer. The highest reported incidence of MTSS in a military setting was 35% of 124 naval recruits participating in basic military training (BMT) in Australia;4 CECS occurred in US Army soldiers at a rate of 0.49 cases per 1000 person-years (4100 cases diagnosed in 5 years).11 The relative risk for young female soldiers to sustain an overuse injury is 2.5 in the Dutch military6 and the relative risk for young female soldiers to sustain an overuse injury in the ERLP category has been reported between 1.11 and 3.1 (Table 1).
Risk factors for ERLP in a military setting
MTSS is an overuse injury involving the interface of the tibial bone and soft tissue.31 ,32 The young soldier reports pain with running and jumping activities over the (posterior) medial tibial border; by definition an area of at least 5 cm or more is tender on palpation. In the early stages of overuse, the pain will disappear after warming up, allowing relatively pain-free participation in the main athletic event, however in later stages of overuse, any walking, running and/or jumping is severely limited by pain, which can last into the next day(s). The natural tendency to heal is favourable. Prolonged rest with targeted stretching and strengthening of leg musculature are associated with activity resumption in most cases.1
The definition of CECS is pathologically elevated pressure in a muscular compartment during exercise, which returns to normal with cessation of exercise. Some researchers claim that the increased intracompartmental pressure leads to disrupted local tissue perfusion,33 ,34 but others doubt this.35–37 Pressure in a muscular compartment can rise acutely (acute compartment syndrome, ACS) or repeatedly with exercise (CECS). ACS is usually caused by trauma and ACS caused by exercise is an extremely rare condition,38 ,39 thought to develop in those who already had CECS.40–42 ACS demands immediate surgical treatment (fasciotomy) to maintain viability of the structures in the muscular compartment.39 ,42 ,43 CECS can present in any muscular compartment of the body, but is most prevalent in the anterior compartment of the leg and the symptoms of CECS depend on the structures located in the affected compartment, particularly nerves.42 ,44
The young soldier with CECS reports a cramping or burning sensation on the anterolateral side of the leg (anterior or lateral compartments) or deep in the calf (deep posterior compartment). The pain is most often related to running or marching, begins at a predictable point after exercise initiation and disappears quickly at cessation of activities, usually within 15 min, although in severe cases the pain can stay on longer. The natural tendency to heal is poor. Without adequate therapy, patients will remain unable to run or march for many years and are forced to permanently reduce their sporting activities.42 ,45–47
Methods
This article reviews the literature concerning the prevention and treatment of ERLP in military settings and describes the current practice of ERLP care in the Dutch military. A comprehensive search was conducted that included MEDLINE (PubMed) for articles in English that were related to ERLP in the military, using the following (truncated) search terms in different combinations: MTSS, CECS, ERLP and military. The latest consultation of Pubmed was December 2015. The intention of this article is to assist healthcare professionals to better help military patients.
Results
Prevention
Initial medical assessment and intrinsic risk factors
The initial medical assessment before employment in the military provides the first opportunity to prevent ERLP as the screening physician can look for intrinsic risk factors for ERLP (Table 1), although these risk factors are often based on small sample sizes with conflicting results. In a review and meta-analysis, it is suggested that reducing body mass index (BMI), navicular drop, ankle plantar flexion range of motion and hip external rotation range of motion may be a good starting point for preventing and treating MTSS.1
There are no prospective studies that determine which of the ERLP risk factors reported in Table 1 are most relevant in the Dutch military. Based on a consensus meeting of senior physicians the following five risk factors are deemed most important in the Dutch military setting: current status (injured at the time of medical examination), a history of ERLP, technique of running and marching, female gender and little prior weight-bearing physical training (defined as: several years of participation in a sport with leg loading such as soccer, track and field, basketball, etc).
If a recruit has several risk factors for the development of ERLP, particularly the five identified above, the physician performing the initial medical assessment can take the following preventative measures: (1) The recruit will be assigned a military job where running and marching is of less importance, (2) The recruit is temporarily denied access to the military to heal and to work on modifiable risk factors or (3) The recruit is denied access to the military permanently when the risk profile for ERLP is particularly unfavourable.
Following the initial medical assessment, the most important factor to prevent injury in military training is a carefully graded increase in physical loading as the literature clearly shows a relationship between weekly training volume (especially running and marching) and the number of injuries to the lower extremity.48–53 The training load must be compatible with the physical abilities of the recruit.
Changing training programmes and extrinsic risk factors
It is known that incorporating extra rest,54 incorporating extra stretching exercises55–57 or assigning running shoes based on plantar shape58–60 do not reduce the number of overuse leg injuries in military settings. In addition, daily supplementation of calcium or prophylactic treatment with bisphosphonate (risedronate) do not reduce the risk of bone stress injuries to the leg.61 ,62 Conversely, there is evidence that calcium plus vitamin D supplementation does reduce the number of lower extremity stress fractures in female recruits with insufficient calcium intake.63 In contrast to all the negative findings, one recent study showed that gait retraining during BMT, including biofeedback on risk factors and a battery of exercises to improve neuromuscular condition, can reduce the incidence of MTSS.64
The role of shoe inlays in the military setting to prevent injury has been controversial for many years. Cushioning insoles in boots can reduce maximal pressure to the heel and forefoot by 37% and 24%, respectively, and users report comfort when wearing them,5–67 but there is limited evidence that the use of shock-absorbing insoles reduces the number of injuries.66–70 Providing custom made biomechanical shoe orthoses shows promising results in some studies,69 ,71 but three systematic reviews all conclude that more research is necessary to underpin an evidence based policy for providing customised shoe orthoses for asymptomatic military recruits.68 ,72 ,73 To provide every soldier with such orthoses as a prevention strategy is too costly;69 a possible compromise is providing prefabricated orthoses.74
The military instructor plays a key role in the prevention of overuse injuries. Experienced instructors who can prevent overexertion in their training groups have less dropout with injuries and better graduation percentages.25 ,75
Primary care: the medical unit on base
Diagnosis of ERLP
The most common diagnoses in young Dutch soldiers with ERLP are MTSS, CECS and a combination of the two; pain from fascial herniae, tibial stress fractures, peripheral nerve impingement (eg, the superficial peroneal nerve) and ACS caused by exercise are all much rarer.
The diagnosis of MTSS may be confirmed with history and physical examination alone. When in doubt, other diagnoses can be excluded by additional investigations (eg, stress fracture by advanced imaging).31 The diagnosis of CECS is confirmed by an intramuscular compartment pressure (IMCP) measurement. Fascial hernia of the anterior and lateral compartments of the leg are often found as a comorbidity of CECS,5 ,42 ,76 but the pathophysiology of CECS and the relationship of CECS to symptomatic and asymptomatic fascial hernia are not fully understood.2
MTSS and CECS are two different diseases. However, based on history and physical examination the distinction may be difficult to make, particularly between MTSS and CECS of the deep posterior compartment.77–79 In addition, many soldiers have complaints compatible with both MTSS and CECS and the clinical presentation may change over time: often initial complaints fit the diagnosis of MTSS, but over time CECS may develop.10
To diagnose ERLP correctly, it is necessary to provoke the complaints with an exercise test and repeat the physical examination immediately after exercise.76 ,80–84 In the Dutch armed forces the ‘Running Leg Pain Profile’ (RLPP) has been developed as a diagnostic tool for ERLP.80 During a standardised treadmill test (increasing speed and incline) performed in running shoes, a patient is asked to give a pain score of 1–10 for four (or six) regions of their legs (anterior compartment and medial tibial border for both right and left legs and the calves are the two additional two regions) (Figure 1). The test contains running and marching and is designed to reproduce symptoms in the military patient group. CECS symptoms may be reproduced best by marching.85 ,86 The RLPP assists in pinpointing an accurate diagnosis and also provides information on the severity of symptoms. In addition, during the test the investigator can judge running biomechanics.80
The Running Leg Pain Profile (RLPP): 1. lateral side right leg; 2. medial tibial border right leg; 3. medial tibial border left leg; 4. lateral side left leg (calves, region 5 and 6, optional).
Treatment of ERLP
Table 2 shows the current treatment guideline based on expert consensus for ERLP in the Dutch Armed Forces. It is not necessary to perform an IMCP measurement before starting conservative treatment for ERLP. The treatment must offer the components presented in Box 1.
Components of the treatment of exercise related leg pain (ERLP) in a military setting
1. Significant reduction of symptom producing activities (running, marching, jumping, etc);
2. Treatment of local pain in soft tissues and reduction of limitations in joint range of motion of ankle, knee and hip;
3. Improvement of modifiable risk factors for ERLP in a military setting (Table 1);
4. Gradual return to leg loading activities;
5. Goal evaluation: is it realistic for this soldier to return to the intended military training and or job?
Treatment guideline for ERLP in the Dutch Armed Forces10
In the Dutch military, the base physician is responsible for starting the treatment of ERLP and ensuring the timelines are adhered to (Table 2). The physician refers the patient to the physical therapist if the initial actions of the guideline are insufficient to reduce the symptoms and invites the patient to return for monthly visits to discuss treatment progress. The treatment programme on base that should lead to return to full duty is divided into two physical therapy phases, a sports phase and a military-specific phase. The transfer from one phase to the next is based on objective test results, such as a pain-free 12 min run is one of the requirements to enter the sports phase of rehabilitation.
Occupational prognosis for MTSS
The average treatment duration for MTSS, when placed in a remedial platoon in the Dutch military, is 4–5 months.6 ,7 This is longer than the 3 months average treatment duration reported in Dutch civilian settings and longer than 82 days, as reported in a large 2015 study of British army recruits.8 ,91 ,107 A possible explanation is that soldiers do not seek medical consultation until their injury has progressed to an advanced stage,4 or that soldiers are not reported cured until they can return to duty, which requires a high level of fitness. In addition, the 4–5 months in the Dutch remedial platoon placement may include a waiting period. After healing the soldier must wait for an appropriate moment to rejoin a training group. The only factor that has been reported to predict duration of MTSS recovery time is BMI, with a higher BMI predicting a longer recovery time.16 Wearing a leg brace does not reduce recovery time, the comfort of wear is poor and soldiers find the braces cosmetically displeasing with duty uniform.108–110
Referral to secondary care
The physician on base may refer the military patient to secondary care in a regional military hospital if treatment of the soldier with ERLP in accordance with the guideline (Table 2) stagnates. Based on consensus of senior physicians, it is recommended to do this after approximately 3 months of conservative treatment.
Secondary care: a military hospital
Diagnosis
Traditionally Dutch military personnel with overuse injuries of the legs and suspected CECS are sent to the out-patient clinic of the department of general surgery of the Central Military Hospital (CMH). Over the last 20 years, the number of new patients visiting the clinic for ERLP has been constant at 250 per year and until recently approximately 150 fasciotomies per year were performed. In the current protocol the soldier with ERLP meets with three physicians in one hospital visit: a surgeon, a primary care sports medicine physician and a physiatrist. The RLPP is recorded and an IMCP measurement is performed in all compartments where the patient has symptoms, in both legs, even if the patient has unilateral symptoms.
To confirm the diagnosis of CECS, an IMCP measurement is necessary. A recent survey of American military orthopaedic surgeons showed that 85% of the respondents believed that the diagnosis of CECS should be confirmed with IMCP testing before surgical treatment, but those who were in practice longer and respondents who saw more patients with suspected CECS per year were more likely to recommend surgical treatment based on clinical diagnosis alone.111 In the Dutch CMH the Stryker measuring device is used to perform IMCP measurements in the 1st minute after exercise according to the RLPP protocol (Figure 2A).112 The Dutch criteria for surgery have been established by Verleisdonk et al,112 but only for the anterior compartment. Currently in most cases with ERLP, at least four compartments are tested (anterior and deep posterior of both legs) and sometimes more. It is necessary to establish criteria for all compartments separately, both in the resting state and post exercise.113 For the time being in the Dutch CMH, the criterion for the anterior compartment (35 mm Hg 1 min post exercise) is used for all compartments. With the Stryker pressure monitor the deep posterior compartment can be reached through the anterior compartment. The advantage is that the skin is penetrated only once for measurement of both the anterior and the deep posterior compartments (Figure 2B,C);77 ,114 there is however a risk of touching a neurovascular bundle,115 but in the CMH, there are no reports of serious complications of the Stryker IMCP measurements. In a British paper, one case of bleeding of the arteria tibialis posterior is mentioned after testing 76 patients.113 Diagnostic utility of the IMCP measurement is improved when measured continuously during exercise85 which requires insertion of a catheter and one Stryker pressure monitor for each muscle tested. Currently the IMCP is still the accepted standard for CECS diagnostics, if performed with local protocols and local reference values.116–118
With the Stryker pressure monitor (A) the anterior compartment (B) and the deep posterior compartment (C) can be reached penetrating the skin only once.
There is an ongoing search for non-invasive diagnostic procedures. Near-infrared spectrometry5 and ultrasound immediately after exercise119 are promising methods which are relatively easy to perform, but not yet accepted as the new standard, because they only reach the anterior compartment. An exercise test inside an MRI machine may be technically possible, but it is not feasible for large numbers of patients per year.120 The ankle-brachial index (ABI) in the 1st minute post exercise may help to differentiate patients with CECS from normal and ABI in combination with the RLPP may provide an acceptable diagnostic alternative in the military setting.121
Conservative treatment of ERLP
Most treatment actions reported in Table 2 have been in use in the Dutch military for many years and are considered ‘standard therapy’. New elements in the conservative treatment of MTSS in a secondary care setting are extracorporeal shockwave treatment (ESWT) and gait retraining. Two studies report that patients with MTSS who receive a standard treatment programme plus ESWT have better outcomes than those who receive the standard treatment only.91 ,105 ESWT treatment on the tibia can be quite painful. In the Dutch military setting, ESWT treatment is available in the primary care sports medicine department only, using a protocol adopted from Rompe et al105 (one session per week, 2000 radial shocks, 8 shocks per second, 2.5 bars of pressure, four or five sessions in total). Practical experience has shown that patients strongly prefer self-administration of ESWT on the tibia (Figure 3). Gait retraining to change running biomechanics can reduce the vertical forces of landing significantly122 with the most important factors in reducing the impact forces of running being a change from a rear-foot to a mid-foot strike103 and increasing cadence, usually through decreasing stride length.123 There is no study that reports the results of gait retraining as a treatment for MTSS.
Self-application of extracorporeal shockwave treatment, a soldier with medial tibial stress syndrome.
In contrast, gait retraining as a treatment for CECS has been described. Diebal et al102 were the first to report that gait retraining for running was effective in reducing complaints and IMCP measurement in military personnel with CECS. Their study population was homogeneous young, fit, officers in training, with CECS of the anterior compartment only. Recently several studies have confirmed the positive effects of gait retraining on the symptoms of CECS of soldiers.86 ,101 ,124 In addition, shoe type also plays an important role in the amount of force placed on the legs in running. So-called ‘low drop/low heel height’ shoes can reduce peak forces on the heel by 25%.90 In earlier studies it was shown that shoes with a negative sole (a slope increase from heel to toe) reduced IMCPs in the anterior compartment during running on average by 20% and that changing shoe type alone may be sufficient therapy to reduce symptoms in patients with CECS.125 ,126 Some authors are of the opinion that pain and increased IMCP caused by faulty running biomechanics requires a new diagnostic terminology of ‘biomechanical overload syndrome’.86
Surgical treatment of ERLP
In the Dutch CMH, no surgical treatment is offered if the diagnosis is MTSS, because the results reported in the literature are poor:127 patients report reduction of pain after surgery, but only 41% fully return to the presymptom level of sports participation.
Until a few years ago, fasciotomy of the affected compartments seemed the only useful treatment for CECS.128–130 In the Dutch CMH, Verleisdonk et al reported that after minimally invasive fasciotomy of 151 compartments in 81 patients (149 anterior compartments and two lateral compartments) 76% of patients experienced significant reduction of pain 6 months after surgery. The average compartment pressure was reduced from 57 mm Hg preoperatively to 25 mm Hg postoperatively.131 In 10 cases however, pressures were not reduced postoperatively, four patients (4.9%) had surgical revision and there were four documented complications (three neuromas and one seroma). Complications of fasciotomy reported in the literature include perioperative vascular damage, haematoma, neurological complaints, damage to the superficial peroneal nerve, deep venous thrombosis, delayed wound healing, postsurgical hernia, persistent ankle pain and cosmetically unacceptable scars.33 ,132–135 The highest reported rate of complications is 15.7%.132 The rate of complications in the Dutch CMH is unknown, but the surgeons indicate that the number of complications of surgery rises with the number of compartments opened during one surgical procedure. Long-term complications of fasciotomy are not well documented.
There is limited written information on the rehabilitation after elective fasciotomy of the leg.136 In some cases it is possible to return to a physically demanding military job.137 The duration of rehabilitation will be 3 months or more.34
Occupational prognosis of CECS after surgery
The prognosis for work in the military is unfavourable after fasciotomy. In a 2010 Dutch analysis of 44 soldiers who underwent fasciotomy of the anterior compartment of the legs in the CMH, 15 patients (34%) returned to their original military jobs, 28 patients left the military (64%) and 25 (57%) still reported symptoms 2 years after surgery (HW Nijhoving. The results of fasciotomy for soldiers. Unpublished paper, Department of Occupational Medicine, Royal Dutch Army, 2013. Dutch.). In an American analysis of 611 soldiers who underwent fasciotomy between 2003 and 2010, 44.7% of patients had symptom recurrence, 27.7% did not return to full duty and 17.3% were referred for medical discharge.132 A limitation of this study was that it was a retrospective review of a database including 32 treatment centres which did not allow for evaluation of diagnostic criteria, surgical procedures and rehabilitation protocols at the respective centres.138 Several recent studies confirm that the results of surgical treatment for CECS in the military are inferior to those in civilian athletes.2 ,132 ,138–140
Based on these insights, the Dutch CMH has changed its policy for surgery for CECS. Fasciotomy is performed only after at least 3 months of conservative treatment, as described in Table 2; preoperatively it is ensured that patients have received gait retraining and that creatine supplementation had been terminated.87 ,88 The number of fasciotomies being performed in the Dutch CMH is declining.
Conclusions
The body of knowledge on ERLP in the military is growing and the number of publications is increasing. Despite these recent developments the occupational problem of ERLP in the military is far from resolved. These overuse injuries continue to have a high incidence, long recovery time and large impact on training. Proactive preventative and rehabilitative management targeting ERLP is necessary to achieve change. The challenge is to convey the current knowledge and the sense of urgency to all physicians and policy makers involved.
References
Footnotes
Contributors WOZ is the main author and guarantor of this review article. Important contributions in content, grammar and style have been made by PHH and AB.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.