June 19, 2024
The question of whether or not a service member with musculoskeletal injuries (MSKIs) will return to duty is a complicated process to answer. And MSKIs significantly impact medical readiness, burden the Military Health System, and contribute to service-connected disability costs. Jeffrey Tiede and Sean Moore question whether the current return to duty process is worth the effort it requires and the resources it consumes while providing unreliable outcomes. Tiede and Moore, based on their respective experiences at the Center for the Intrepid and the San Francisco VA, propose that the process must be reviewed and further developed by experts in complex systems in order to provide a timely and reliable framework for decision.

Musculoskeletal injuries (MSKIs) significantly impact medical readiness, burden the [Military Health System], and contribute to service-connected disability costs.

Sometimes simple questions do not have simple answers. As leaders in an organization with a keen focus on readiness, commanders need to know the health status of their assigned personnel. “Will my Soldier/Sailor/Airman/Marine return to duty?” This yes/no question deserves a prompt and an accurate response from those of us in the Military Health System (MHS). However, when it comes to some of the most common injuries encountered in military service, musculoskeletal injuries, the answer is often anything but simple. The challenge of identifying return to duty (RTD) considerations involves a complex and uncertain decision-making process. Experts in musculoskeletal care spend an inordinate amount of time developing assessments and heuristics regarding fitness for duty, however, this work does not always accurately predict who will RTD and when. Working towards more complex mental models of medical readiness determinations will allow senior leaders to better distribute available resources and mitigate the risk of medically non-ready service members.

Musculoskeletal injuries (MSKIs) significantly impact medical readiness, burden the MHS and contribute to service-connected disability costs. MSKIs affect 800,000 service members annually, the great majority of which are classified as overuse injuries. The Department of Defense spends over $3.7 billion per year in direct and indirect costs for MSKIs. In addition to the financial burden, MSKIs exact a toll on the readiness and the lethality of the remaining force. 59% of total lost duty days due to medical conditions are due to MSKIs, as compared to 10% for behavioral health conditions. Given the continued detriment to medical readiness, it is unclear if MHS’s large expenditure on treating MSKIs is providing a meaningful return on investment.

We propose a mental model that places the RTD question in the realm of complex systems. Although senior military leaders are familiar with systems thinking, a brief discussion on complexity provides a useful foundation in this context. Complexity is characterized by nonlinearity and sensitivity to internal feedback. War, like other human endeavors, is complex. Alan Beyerchen’s discussion of Clausewitz in the setting of complexity is a foundational work for military theorists. In his paper he translates the Clausewitzian Trinity using the language of modern complex systems thinking. Framing war, specifically counterinsurgency, as a complex system is reiterated by GEN Stanley McChrystal in his popular book “Team of Teams.”

Nonlinearity is an essential component of complexity. The nonlinear system can evolve along a number of different pathways and is not amenable to reductionist logic. Additionally, complexity is characterized by sensitivity to internal feedback where the system’s interaction among nodes depends on earlier interactions. The force of one protagonist’s action in conflict will both influence and be influenced by the counterforce of the other. The initial interaction of force/counterforce will influence subsequent exchanges.

The determination of RTD for MSKIs is nonlinear and complex. Unfortunately, medical professionals cannot reduce readiness determinations to algebraic equations. A myriad of factors including access to care, unit norms, personality and underlying physical fitness affect the incidence of MSKIs, whether the injured seek medical care and the ultimate reduction in unit’s medical readiness. Predictors of RTD include Military Occupational Specialty (MOS)/Area of Concentration (AOC), age, sex, body composition, comorbid behavioral health condition, education, smoking status, etc. All of these factors contribute to a complicated equation with multiple variables but do not themselves constitute a complex system. Complexity arises when service members matched in injury, severity, treatment, physical fitness, MOS, etc., experience different outcomes.

In complexity, initial conditions have an exaggerated and variable role in final determination. Grit is one of the personality traits or initial conditions which can cause disparate outcomes. In addition to measurable factors like demographics and grit, there are any number of immeasurable factors which contribute to nonlinearity: Does the service member like their job? Do they derive existential worth from service? What does their spouse desire? The answers to these questions can sometimes be more impactful in RTD than the specifics of the injury or physical variables, but they are not systematically factored into the prediction of RTD. Wilson et al. recently demonstrated that individual, interpersonal, health care system and institutional factors significantly and variably influenced RTD, and patients placed less emphasis on physical limitations than clinicians in RTD determination.

How can senior leaders approach MSKIs to mitigate risk and ultimately reduce costs within this complex system?

Like nonlinearity, the internal feedback of the RTD system, the force/counterforce, determines disability. In our analogy, perceived injustice best exemplifies this internal feedback. Disability due to MSKIs correlates with the psychometric properties of perceived injustice or victimhood. Furthermore, treatment for many benign MSKIs like mechanical low back pain is progressive exercise. Patients with high levels of kinesiophobia, fear of movement, have worse outcomes. Envision a scenario where a service member was injured during physical training in a unit that they perceive as hostile. The service member’s kinesiophobia enforces distrust of the medical providers who recommended physical therapy and exercise. Noncompliance and lack of progression then create a negative feedback loop which the service member associates with higher levels of injustice. These variables are not amenable to quantification and they differ in each MSKI. The internal feedback of this complex system plays a vital role in RTD.

How can senior leaders approach MSKIs to mitigate risk and ultimately reduce costs within this complex system? The Army Futures Command is positioned to develop an MSKI RTD concept. Whether establishing a medical readiness Cross-Functional Team or Capabilities Development Integration Directorate (CDID), bringing experts in systems-thinking together with clinicians will encourage not only a viable concept development but also a successful execution. Nested within a comprehensive RTD concept, predictive analytics utilizing artificial intelligence (AI) will provide some insight into the RTD question. Accurate predictions require high quality, salient data including heretofore overlooked factors (e.g., ASVAB score, grit score and body composition). Like other AI initiatives, utilizing technology in RTD determination requires the highest ethical and data protection standards.

Whether conducting a military-specific functional capacity examination or a simulated RTD assessment, clinicians must continue to refine the physical assessments of fitness for duty. Here at the Center for the Intrepid, we continue work on the Readiness Evaluation during simulated Dismounted Operations (REDOp) assessment. Both physically and cognitively demanding, REDOp utilizes an immersive virtual reality environment to simulate dismounted patrol and assist with RTD prediction. Future iterations must incorporate psychosocial assessments (e.g., perceived injustice scales and pain catastrophizing scores) to improve the RTD predictive value.

Finally, the discipline of behavioral economics provides lessons on complex systems. “Nudging” is the use of positive reinforcement and suggestions to mitigate biases and influence choices. How can the system “nudge” service members in their rehabilitation from MSKIs? Perhaps conducting a MSKI clinic before duty hours would lessen the incentive to miss work. A comprehensive assessment of contradictory incentives (finances, time off, etc.) is foundational for any proposed changes in policy. Policy changes may be politically sensitive (disability payments) and service-wide (recruitment); therefore, guidance is required from the highest echelons.

MSKIs consume a staggering amount of resources in terms of direct costs and associated disability. MSKIs also significantly deteriorate the Joint Forces’ readiness and lethality. Action is required. Clinicians have difficulty in predicting when or if a Soldier/Sailor/Airman/Marine will RTD after injury. The difficulty arises because RTD determination is not amenable to reductionist logic; RTD determination is complex. RTD determination requires concept development by experts in complex systems thinking collaborating with experts in the MHS. Furthermore, a new model for RTD determination for service members with MSKIs may provide a framework for decision support in other healthcare delivery scenarios where complexity exists. Integrating the DoD’s systems experts with clinicians will facilitate concept development and execution in complex medical problems and ultimately improve not only the readiness of the force but also the wellbeing of individual patients.

COL Jeffrey Tiede, MD is a pain management physician who serves as Director of the Center for the Intrepid, Brooke Army Medical Center, JBSA Ft. Sam Houston, TX. He is also the Command Surgeon for the 7th Mission Support Command (USAR) in Kaiserslautern, Germany.

MAJ Sean Moore, MD is a psychiatrist and pain specialist for the San Francisco Veterans Administration as well as the 3rd Med Detachment, USAR.

The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of Brooke Army Medical Center, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the U.S. Army War College, the U.S. Army, or the Department of Defense.

Photo Credit: U.S. Army Center for the Intrepid


  1. I was wondering if there was any data available servicemen and women who were able to remain on active duty after a ULA (Upper body Limb Amputation) We have an integration system that will allow service men and women the optio to remain on active duty. We are listed with the US Department of Laor as a “Reasonable Accommodation” for employment. W also have the S.P.IR. System which gives them the ability to safely manipulate and use modern firearms.

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