Successful management of work-attributed musculoskeletal conditions requires the clinician to be knowledgeable about the injury as well as the individual’s occupation, essential job functions, and environment. This chapter will provide an overview of specific musculoskeletal conditions attributed to performing job-related tasks. We will also discuss the return to work process as it relates to workers’ compensation and disability determination in the setting of fitness-for-duty and own-occupational disability. Of note, many of the traditional occupations and associated job functions that have historically been associated with work-attributable musculoskeletal disorders have diminished secondary to advances in automation and engineering in the developed world and, in certain cases, this work has shifted to other workforces globally.
The US civilian workforce has consisted of between 143 and 159 million persons over the past 15 years and represents roughly 60% of the total US population.1
Men and women are roughly employed at the same rate (53% vs. 47%) with women more likely to engage in part-time work (25% vs. 12%).1 Age, gender, race, occupation, and industry all influence labor force participation. In addition, the labor market and the individual’s decision/ability to participate in the workforce has many other drivers beyond demographics or individual health status, such as geographic and seasonal variations in industry and the overall strength of the national and international economies. Providers should be cognizant of these complex interactions when addressing the individual’s ability to enter or return to the workforce.
Workplace exposures to chemicals, noise, dust, radiation, and certain biological exposures are subject to various regulations and standards. In the United States, the most widely known standards are provided by the Occupational Safety and Health Administration (OSHA). The scope of the OSHA standards is broad and addresses health and safety risks on a variety of topics including walking-working surfaces, ventilation, noise, nonionizing radiation, hazardous materials, personal protective equipment, electrical work, machine guarding, and fire protection.2
OSHA also requires employers with more than 10 employees to keep records of work-related injuries and illnesses, commonly referred to as an OSHA log. Employers with <10 employees and low-risk industries (e.g., most retail stores, restaurants, private offices of dentists and physicians) are exempt from general recordkeeping but must report to OSHA any workplace incident that results in a fatality, inpatient hospitalization, amputation, or loss of an eye.3 In 2015, there were approximately 2.9 million OSHA-reportable nonfatal workplace injuries and illnesses, a rate of 3 cases per 100 full-time workers. Total recordable cases (i.e., cases requiring more than first aid) and DART (days away from work, job transfer, or restriction) rates are lowest in nongovernment institutions, with rates varying by industry as well as the size of the employer. Law enforcement, nursing and residential care facilities, and construction have the highest rates of total OSHA recordable cases (Fig. 99–1).1 The private-sector occupations with the highest number of cases with days away from work include tractor-trailer drivers, general laborers, material movers and nursing assistants.1 Overexertion and bodily reaction accounted for 33% of total recordable cases (TRC) in 2015, with falls, slips and trips accounting for 27% of TRC. Musculoskeletal disorders (MSDs), specifically tracked by OSHA, account for 31% of the total cases in 2015, with transportation and construction trades reporting the highest rates of MSDs.1 The separate tracking of MSDs highlights the importance of MSDs as workplace injuries and reducing MSDs in the workplace continues to be an OSHA priority as the median days away from work for MSD cases is higher (12 days) compared to all other cases (8 days) with days away from work.1
Within the broad industry classifications, there is widespread variation of risk of developing musculoskeletal symptoms. A recent NIOSH investigation of MSDs found that 73.3% to 77.6% of poultry slaughter and evisceration workers reported neck or upper extremity symptoms compatible with cumulative trauma disorders over a 1-year period. Ninety percent of diagnostic sonographers report that they are scanning in pain with half of the subjects reporting that they were given a musculoskeletal diagnosis for their symptoms.4 Even under the best lifting conditions, the weight of adult patients exceeds the lifting capacity of health care personnel and caregivers.5
ATTRIBUTING MUSCULOSKELETAL CONDITIONS TO JOB-RELATED TASKS
Despite the widespread interest in prevention and treatment of work-attributed musculoskeletal disorders, there are no standard criteria for defining MSD cases.6 Historically, studies have focused on neck and upper extremity conditions such as cervical strain, rotator-cuff tendinitis, shoulder impingement, epicondylitis in the elbow, carpal tunnel syndrome, wrist tendinitis, and hand-arm vibration syndrome. In the past, minimal attention has been paid to other conditions, such as myofascial pain and lower extremity conditions.
An additional limitation of MSD research is the difficultly to quantify both the acute/recent exposures as well as cumulative exposures, especially for complex tasks. A comprehensive NIOSH report in 1997 explored the causal relationship between physical work factors and MSDs. The strongest evidence in support of a causal relationship was when the exposures were considered as a group, rather than an individual physical task (Table 99–1).6
|Strength of Evidence|
|Work Exposure||Strong Evidence||Some Evidence||Insufficient Evidence|
|Neck and neck/shoulder|
|Carpal tunnel syndrome|
|Hand-arm vibration syndrome|
|Heavy physical work||X|
|Whole body vibration||X|
|Static work posture||X|
Even when one considers the limitations of workplace MSDs research, the widespread use of the term “repetitive-motion injuries” should be discouraged as the term implies a single causal exposure that has resulted in pain or dysfunction. With minimal exceptions, every essential job function is a collection of tasks. Therefore, eliminating a single motion or physical demand is unlikely to result in improvement in symptoms. In contrast, eliminating or modifying the collection of tasks attributed to the workplace MSDs has a better chance of achieving the desired effect. However, eliminating or modifying one job-related task may increase the demands on the rest of the kinetic chain responsible for performing other job-related tasks. This has been seen in sonographers where neutral wrist scanning was encouraged to reduce wrist problems—now the most common discomfort is in the elbow and shoulder girdle.7
EVALUATION OF OCCUPATION-ATTRIBUTED MSK CONDITIONS
In addition to the usual elements of the physiatric history and physical examination, the treating physician should generate an occupational history when assessing a patient for an occupation-attributed musculoskeletal conditions. An occupational history focuses on both the individual’s work environment and the interactions between the individual and their employer. Pertinent information includes documenting the individual’s essential job functions, level of supervision, shift-work, duration of employment (how long they have worked in their current position, current location, current employer, and/or current occupational classification), level of education and other formal vocational training, and the physical tasks associated with their essential job functions. For employer-based providers, this information can also be used to inform strategies to reduce or prevent similar symptoms in other workers with the same or related essential job functions. For example, if a worker with a sprained wrist mentions that they are the third worker in the last year to present with these symptoms, there is likely value in performing a job task analysis to identify the risks for injury and mitigating these factors. The following pages describes upper and lower extremity conditions that have been historically attributed to a specific task and/or occupation. For completeness sake, low back pain in the workplace setting is briefly described; however, a full discussion of low back pain in the workplace setting is beyond the scope of this chapter.
Any occupation that requires repeated/sustained wrist extension or repeated pinching/ grasping can result in lateral epicondylitis; the condition is, therefore, not limited to sports-related (i.e., one-handed tennis back hand) injuries. Classically, this is tendonitis to the extensor carpi radialis brevis tendon at the lateral humeral epicondyle, but can affect the extensor carpi radialis longus at the supracondylar line (Fig. 99–2).
Anatomy of the forearm: (A) lateral view, (B) superficial muscles, (C) deep muscles of the posterior forearm. (Reproduced with permission from Chapter 32. Forearm. In: Morton DA, Foreman K, Albertine KH, eds. The Big Picture: Gross Anatomy, New York, NY: McGraw-Hill; 2011.)
Pain with resisted extension (as seen in the Cozen or Chair tests) or with activities such as wrist dorsiflexion or gripping activities is typically reported by the patient (Fig. 99–3). The differential diagnosis includes radial tunnel syndrome, C6 radiculopathy, and (if associated with acute trauma) proximal radius fracture. Usual treatment includes work modification to minimize contributing activities with the focus on a better anthropomorphic match between the user and their work environment in contrast to a one-size-fits-all design strategy. Acute pain can be treated with anti-inflammatories, cold pack massage over the extensor origin, rest, a wrist extensor strengthening regimen, or use of a counterforce (“tennis”) brace. Chronic lateral epicondylitis treatment strategies in the context of employment are more controversial. Some common treatments include steroid injection, platelet rich plasma, dry needling/trigger point injections, physical therapy to include isometric and concentric exercises, and stretches.8–11 Research into many of these strategies is mixed, at best. Some recalcitrant cases may be candidates for surgical debridement of the ECRB/L tendon origins.
Similar to tennis elbow, this condition was initially described in a sports-related capacity. Patients often describe pain along the medial elbow with activities, indicative of a tendonitis of the proximal flexor origin. Patients with occupations that require repeated wrist flexion or pronation, or repeated finger flexion may present with symptoms of medial epicondylitis. Physical exam findings include focal tenderness to palpation of the medial epicondyle and medial epicondylar pain occurring with resisted wrist flexion. The differential diagnosis includes ulnar nerve entrapment at the elbow, ulnar collateral ligament strain, referred C8–T1 radicular pain, and intra-articular pathology at the elbow. Treatment includes work modifications and relative rest. Unlike lateral epicondylitis, steroid injections are not recommended due to risk of ulnar nerve damage.11,12
Olecranon bursitis can be found in any vocation that increases stress, irritation, or friction at the olecranon. Focal irritation and swelling can be seen as the olecranon bursa reacts with this external provocation. Acute cases of this condition can occur with a systemic inflammatory process or infection, but are rarely seen in an occupational setting. However, acute trauma to the posterior elbow may incite the bursitis process.
In general, patients present with focal fluctuant swelling and pain at the olecranon process (Fig. 99–4). Acute bursitis attributed to an occupational exposure should be evaluated like other cases of acute bursitis, including consideration of infectious or crystalline etiology. Chronic bursitis is seen in a variety of systemic inflammatory processes, such as CREST syndrome (limited scleroderma) and rheumatoid arthritis, as well as crystalline disease such as CPPD (calcium pyrophosphate deposition) or gout.
Treatment focuses on work modification to reduce friction and irritation at the olecranon, including an elbow pad or temporary elbow immobilization. In acute cases, bursal aspiration (with appropriate infectious/crystalline workup) followed by steroid injection is commonly used. In chronic or refractory cases, surgical resection of the bursa may be required.13
DeQuervain’s is a tenosynovitis of the tendons and tendon sheaths of abductor pollicis longus and extensor pollicis brevis that compose the first dorsal compartment of the forearm. Work-associated conditions associated with DeQuervain’s tenosynovitis involve overuse of the thumb and wrist, especially with extension and radial deviation. Common physical job tasks include repetitive lifting and hammering. Clinical findings include focal pain and swelling along the radial/dorsal portion of the thumb. The classic diagnostic test in DeQuervain’s is the Finkelstein test, where the patient’s pain is exacerbated when they ulnar deviate at the wrist when holding the thumb flexed into the palm (Fig. 99–5).
The differential diagnosis includes scaphoid fracture (acute) and carpometacarpal (CMC) arthritis at the base of the thumb. Treatment includes relative rest and reducing/restricting/eliminating physical job tasks that require supination. Additional management options are utilization of cold packs, anti-inflammatory medication, and a thumb spica splint. For more chronic issues, local steroid injection into the affected tendon sheath, or even surgical decompression of the first extensor compartment may be required.14
Carpal tunnel syndrome (CTS) is the clinical diagnosis of a median mononeuropathy at the wrist. In acute CTS, there is a direct change in anatomy between the transverse carpal ligament and the carpal bones, resulting in compression of the nerve (Fig. 99–6). Acute CTS can be seen with acute edema or a Colles fracture of the radius. Chronic CTS is often attributed to physical tasks such as forceful gripping, repetitive forceful wrist and finger movement, or traumatic high-frequency vibration in the hands. Patients will often describe paresthesias, numbness, or pain in the thumb, index, long, and lateral portion of the ring fingers. In addition, patients will report that their symptoms are exacerbated by sleeping or performing activities that involve prolonged wrist flexion or extension (i.e., reading, driving, talking on the phone).
Anatomy of the carpal tunnel. (Reproduced with permission from Davenport M, Tang P. Injuries to the Hand and Digits. In: Tintinalli JE, Stapczynski J, Ma O, Yealy DM, Meckler GD, Cline DM, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e New York, NY: McGraw-Hill; 2016.)
On physical examination, patients with chronic CTS may present with thenar weakness or atrophy of abductor pollicis brevis. There are several provocative tests described in the literature, such as the Phalen’s test, Tinel’s Sign over the Carpal tunnel, the Carpal Compression test, or the Scratch Collapse test—all with varying degrees of sensitivity and specificity (Fig. 99–7).
Phalen’s test and Tinel’s Sign for carpal tunnel syndrome: (1) The carpal tunnel: the flexor retinaculum in the wrist compresses the median nerve to produce hyperesthesia in the radial digits. (2) Tinel’s sign: percussion on the radial side of the palmaris longus tendon produces tingling in the digital region. (3) Phalen’s test: hyperflexion of the wrist for 60 seconds produces pain in the median nerve distribution, which is relieved by extension of the wrist. (Reproduced with permission from The Nervous System. In: LeBlond RF, Brown DD, Suneja M, Szot JF, eds. DeGowin’s Diagnostic Examination, 10e New York, NY: McGraw-Hill; 2014.)
Office-based ultrasound can be used to visualize the median nerve at the carpal tunnel and appears to be a promising technology to aid in the diagnosis of CTS.15 The differential diagnoses includes median mononeuropathy at a more proximal site and cervical radiculopathy. Electrodiagnostic studies can be useful to diagnose and assess the severity CTS and exclude other confounding diagnoses.
Treatment includes optimization of job tasks to reduce the movements that exacerbate symptoms. Relative rest and splinting the wrist in neutral (especially at night) can help with symptoms. If these strategies are not sufficient, steroid injections to the carpal tunnel, or even carpal tunnel release surgery are options.16,17
As the ulnar nerve passes through the cubital tunnel between the medial epicondyle and olecranon, it becomes more superficial and, therefore, susceptible to compression. Job tasks associated ulnar neuropathy at the elbow include activities in which a patient bears their weight through a flexed elbow or holds their elbows flexed for a long period of time. Acute injuries can also occur, particularly when the flexed elbow is struck in a postero-medial location. Ulnar neuropathy at the elbow is sometimes referred to as “cubital-tunnel syndrome,” which does not accurately reflect the anatomy as the ulnar nerve is less likely to become entrapped within the cubital tunnel proper, and more likely to be entrapped or irritated at a slightly more proximal locus.
Patients will often describe paresthesias or pain in the medial forearm and the small and ulnar half of the ring fingers. In chronic or severe cases, this can be accompanied by weakness or intrinsic/hypothenar hand atrophy. Tinel sign or scratch collapse testing over the cubital tunnel may elicit paresthesias or weakness, respectively. The elbow flexion test may reproduce the patient symptoms (Fig. 99–8). As with median mononeuropathies, ultrasound, MRI, or nerve conduction studies can be helpful in diagnosing this condition and localizing the damage.
Elbow flexion test for 60 seconds. With ulnar neuropathy at elbow, tingling or numbness may occur in fourth and fifth digits. It can be useful to follow progress of treatment by recording the time to onset of symptoms. (Reproduced with permission from Rempel DM, Amirtharajah M, Descatha A. Shoulder, Elbow, & Hand Injuries. In: LaDou J, Harrison RJ, eds. CURRENT Diagnosis & Treatment: Occupational & Environmental Medicine, 5e New York, NY: McGraw-Hill; 2013.)