Scaphoid Fracture Detection in a Military Population: A Standardized Approach for Medical Referral

Transcription

1 MILITARY MEDICINE, 171, 5:404, 2006 Scaphoid Fracture Detection in a Military Population: A Standardized Approach for Medical Referral Guarantor: LTC John Faillace, MC USA Contributors: CPT Michael T. Burtis, MC USA*; LTC John Faillace, MC USA ; Leslie F. Martin, MD MPH ; CPT Shawn Hermenau, MC USA Objective: The objective was to test, refine, and implement an algorithm for early detection and referral of clinical scaphoid fractures by U.S. Army medical personnel. Our goal was to reduce complications resulting from delayed diagnosis and to improve outcomes affecting soldier health and unit readiness. Methods: Data on scaphoid fractures treated in the orthopedic department at Tripler Army Medical Center were collected from January 1, 2001, through December 31, Demographic variables included gender, age, and military rank. Results: The incidence of scaphoid fractures in our population was 43 cases per 100,000 personnel per year. An algorithm to guide nonorthopedic providers was developed after review of the medical literature. Conclusion: We present an algorithmbased approach to soldiers presenting with post-traumatic wrist pain. The algorithm was fashioned with the aim of reducing complications and poor outcomes associated with delayed diagnosis of scaphoid fractures, affecting soldier health and unit readiness. A prospective study of the algorithm is underway. Introduction ractures in the active duty population affect soldier and unit F readiness for 2 months after injury, because of healing time and subsequent rehabilitation. Moreover, scaphoid fractures take longer to heal than the typical fracture, for reasons discussed below, and readiness can be affected for 3 to 4 months. Enlisted medical personnel in the U.S. military are the gatekeepers through which soldiers gain access to medical care, even if they have a scaphoid fracture. Considering the confusion in diagnosing and managing injuries of the carpal scaphoid, we present an algorithm to heighten clinical suspicion for scaphoid fracture among our medics. The algorithm is based on a review of the medical literature, with the intent to increase utilization of appropriate medical resources. One goal in particular is to reduce complications resulting from delayed diagnosis, thereby decreasing poor outcomes that affect the soldier s health as well as unit readiness. The Study Population Our study population included the active duty members of the armed forces serving in Hawaii. Active duty service members referred to the orthopedic department at Tripler Army Medical *Department of Radiology, Tripler Army Medical Center, Honolulu, HI Orthopedic Surgery Service, Darnall Army Community Hospital, Fort Hood, TX Division of Public Health, Medical College of Wisconsin, Milwaukee, WI Department of Orthopedic Surgery, Tripler Army Medical Center, Honolulu, HI This manuscript was received for review in December 2004 and was accepted for publication in May Center for scaphoid fractures between January 1, 2001, and December 31, 2003 (n 50), were included. Demographic characteristics of the 25th Infantry Division, the total armed forces serving in Hawaii, and the fracture group are included in Table I. Active Duty Health Care Active duty members of the U.S. Army receive their health care through the Department of Defense managed care plan known as TRICARE, 1 with military providers delivering the majority of care at designated medical treatment facilities. Access to garrison medical treatment facilities is hierarchical in nature (Fig. 1), and the unit-level Army medical specialist (medic) functions as the initial caregiver in most circumstances. This relationship exists because most soldiers seeking care must first report to their individual units for sick call. A medic assigned to the unit s battalion aid station formulates an initial assessment and plan in accordance with his or her level of experience or as guided by the Algorithm-Directed Troop Medical Care (ADTMC) plan. A wide range of presenting complaints are evaluated and managed by enlisted medical personnel. The ADTMC provides quality assurance and assists the medic in determining whether referral to the supervising medical officer is required. However, the ADTMC does not include an algorithm for post-traumatic wrist pain adequate to address suspected scaphoid fractures. Scaphoid fractures are prone to delayed union, nonunion, avascular necrosis, and progression to osteoarthritis, 2,3 with consequent disability. This underscores the need for a standardized detailed approach to evaluating soldiers with acute wrist trauma. Army physician assistants (PAs) supervise the battalion aid station and are ultimately responsible for the primary care of soldiers within the battalion. Soldiers in units without assigned medical assets receive their health care from troop medical clinics staffed by physicians and PAs. These providers do not have specialized training in orthopedics. A physician or PA commands the troop medical clinic and decides when referral for more-definitive care at the Army community hospital or Army medical center is required. Therefore, regulation of an individual soldier s access to care occurs at various points in the hierarchy. Often, of necessity, the medic determines the allocation of medical resources. Increasing the medic s awareness of the mechanisms of injury and clinical examination findings for suspected scaphoid fractures should improve the sensitivity and specificity of evaluations, as well as timely referral to the supervising medical officer. Moreover, earlier diagnosis and appropriate treatment should reduce the rate of nonunion and avascular necrosis associated with inadequate 404

2 Scaphoid Fracture Detection 405 TABLE I DEMOGRAPHIC CHARACTERISTICS OF PATIENTS WITH SCAPHOID FRACTURES AMONG ACTIVE DUTY PERSONNEL SERVING IN THE 25TH INFANTRY DIVISION AND OTHER ARMED FORCES, HAWAII (SOURCE: CENSUS OF POPULATION AND HOUSING, 2000) Variable Scaphoid Fracture, Active Duty (n 50) therapy and should decrease poor outcomes. Soldier health and unit readiness will be improved as a result of earlier management. Scaphoid Anatomy and Blood Supply The ossis scaphoideum is the largest carpal bone on the radial side of the wrist and occupies the floor of the anatomical snuffbox. The extensor pollicis longus and extensor pollicis brevis tendons form the dorsal boundaries (Fig. 2). The position of the scaphoid is integral to wrist motion. It forms an articulation with both the proximal and distal carpal rows, 4 synchronizing wrist kinematics; this adds to its susceptibility to injury. One of the first concerns after any injury to the wrist is the presence of fracture. The most common wrist fracture among adults is fracture of the distal radius, 5 with scaphoid fracture being the most common carpal injury. These fractures share a common mechanism of injury, and axial loading predisposes both the radius and scaphoid to fracture. Moreover, nearly three-fourths of all scaphoid fractures are the result of Schofield Barracks (n 14,428) Proportion (%) Wheeler AFB (n 2,289) All Armed Forces, Hawaii (n 38,992) Gender Male Female Age 18 years years years years years years years a 92.0 Rank E1 E E5 E WO 0 O1 O AFB, Air Force Base. a Age at which most scaphoid fractures occur. Fig. 1. Hierarchy of care, showing access of care beginning at the soldier s individual unit. Fig. 2. Anatomical snuffbox. The dorsal boundary of the anatomical snuffbox (single, thin, black arrow) formed by the extensor pollicis longus (double black arrows) and extensor pollicis brevis (white arrow) tendons and the first compartment (single, large, black arrow) are shown. falls on the outstretched hand. 6 Axial or longitudinal forces transmitted through the scaphoid during injuries from falls on the outstretched hand are the result of wrist hyperextension or forced ulnar deviation. Compounding the anatomical vulnerabilities of the scaphoid is a tenuous blood supply (Fig. 3). A major portion of the scaphoid arterial supply arises from the radial artery. Lateral volar, dorsal, and distal radial artery branches share in the burden. Because the surface is largely covered by articular cartilage, the dorsal branches entering the bone distally provide most of the vascular supply to the proximal scaphoid. Fracture healing of the proximal pole of the scaphoid is dependent on dorsal branches, supplying 70% to 80% of the proximal scaphoid. 7 Unlike most fractures, scaphoid fracture healing frequently occurs in only one fragment instead of both.

3 406 Scaphoid Fracture Detection Fig. 3. Arterial supply of the scaphoid (volar surface). The lateral volar branches of the radial artery (long, thin, black arrow), the palmar scaphoid branches (short, thin, black arrow), and the distal scaphoid branches (thick black arrow) are shown. Pathophysiology Fractures of the carpal scaphoid typically occur between 15 and 35 years of age 8 and represent approximately 50% to 80% of all carpal fractures. 9 Confusion and improper treatment often hamper the diagnosis and appropriate management of scaphoid fractures. The lack of acceptable intervention during the initial postinjury interval may lead to complications with significant morbidity and potential for long-term disability. The differential diagnosis for soldiers presenting with acute wrist pain from falls on the outstretched hand or from direct trauma to the wrist should include scaphoid fracture until proven otherwise, even after initial radiography. Herneth et al. 10 reported that, in the immediate postinjury interval, as many as 65% of scaphoid fractures are radiographically occult. Brydie and Raby, 11 in a study of 195 patients, found occult fractures for nearly 40% of their patients with clinical scaphoid fracture and normal radiographs at presentation. Chakravarty et al. 12 reported that, of patients presenting for radiographs for suspected fracture of the scaphoid, the proportion with negative X-rays is 10% to 36%. In addition, one of the largest prospective studies to date, that of 1,052 patients by Munk et al., 13 showed that 6% of 160 scaphoid fractures went undiagnosed until follow-up X-ray examination 2 weeks after injury. In cases of clinical scaphoid fracture and normal X-rays, immobilization followed by repeat radiography in 10 to 14 days is the standard of care in the medical literature. 14 Of particular interest, there is ongoing debate in the literature with respect to a reliable approach to diagnostic imaging of scaphoid fractures. In a study of interobserver agreement in radiographic interpretation, Tiel-van Buul et al. 15 concluded that radiographs are no longer the standard method. Options include bedside fluoroscopy, scintigraphy, computed tomography, and magnetic resonance imaging (MRI). The Value of a Standardized Approach to Physical Findings References to the importance of judicious screening examinations for clinical scaphoid fractures are not infrequent in the medical literature. 12,13,15 17 Since the advent of evidence-based medicine, quality data are required to support medical decisions regarding diagnostic tests. Our major aim is to produce an algorithm-directed approach for the physical evaluation of soldiers presenting with possible carpal scaphoid injury. Medics treating soldiers at the unit level could use the algorithm as a guideline for referral to the supervising medical officer, Army community hospital, or medical center, as indicated. The proposed algorithm accounts for pretest probability statistics based on detailed mechanisms of injury and the incidence of scaphoid fractures in the military population of Hawaii. Moreover, a review of physical examination findings in major studies of clinical scaphoid fracture from 1997 to 2003 is included. The derivation of quantitative statistics, i.e., positive predictive value (PPV), negative predictive value, sensitivity, and specificity, is referenced in Table II. Cervik et al. 17 prospectively studied the value of physical examination findings in predicting wrist fracture among 55 patients with acute wrist injury. Patients were referred for MRI of the wrist in cases of discrepancy between clinical examination findings and initial X-ray studies. The examination findings with the highest PPVs were pain on supination (PPV of 96%) and wrist edema (PPV of 95.2%). Pain with prehension had a higher PPV than local scaphoid tenderness (PPVs of 89.3% and 67.3%, respectively). However, local wrist pain on active motion had a sensitivity of 97.1%. Although not specific to scaphoid fractures alone, this study confirms the importance of physical examination findings for clinically suspected fractures. In the first prospective study of combined clinical symptoms in scaphoid fracture, Parvizi et al. 16 studied anatomical snuffbox tenderness, scaphoid tubercle tenderness, tenderness with longitudinal compression of the thumb, and limited motion of the thumb for 215 patients. Information was obtained at the time of presentation and at follow-up evaluation. Confirmation of scaphoid fracture was made with initial radiographs and subsequent radiographs obtained at 2 weeks or with bone scans. In total, 56 patients (26%) demonstrated fracture of the scaphoid. Initial sensitivity of anatomical snuffbox tenderness, scaphoid tubercle tenderness, and longitudinal compression of the thumb was 100% at presentation. Specificities were 9%, 30%, and 48%, respectively. When clinical signs were combined, however, specificity improved to 74%. Limited motion of the thumb TABLE II QUANTITATIVE INDICATORS IN DIAGNOSTIC RESEARCH Test Formula Definition PPV TP/(TP FP) Ratio of TP test results to all positive test results Negative predictive value TN/(FN TN) Ratio of TN test results to all negative test results Sensitivity TP/(TP FN) TP test ratio Specificity TN/(TN FP) TN test ratio TP, true positive; FP, false positive; TN, true negative; FN, false negative.

4 Scaphoid Fracture Detection was 69% sensitive and 66% specific. Those authors proposed that clinical examination findings used in combination would improve accuracy in the clinical diagnosis of scaphoid fractures. 16 Saxena et al. 18 studied 124 patients with clinical scaphoid fractures. Their protocol was consistent with clinical examination and radiographs at initial presentation. All fractures were treated with orthopedic referral, whereas patients with negative radiographs received casts and underwent out-of-plaster examinations 2 weeks after injury. Patients with persistent clinical scaphoid fractures had repeat radiographs. The study protocol yielded a total of 16 patients with scaphoid fractures. The overall PPV of clinical examination in that study was 13%, similar to the aforementioned study by Munk et al., 13 in which the PPV was 14%. It is important to note that the aim of this study was not to evaluate clinical findings directly. In a study evaluating MRI for 195 patients with positive clinical evaluations and no evidence of fracture on initial radiographs, Brydie and Raby 11 confirmed the presence of 37 scaphoid fractures. The PPV for their study was 19%. Similarly, Tielvan Buul et al., 4 in a report of their series studying bone scanning for 160 patients with clinical scaphoid fractures and negative initial radiographs, confirmed 56 scaphoid fractures, consistent with a PPV of 35%. Our Suggested Approach We cannot overstress the importance of early recognition of scaphoid injury by medics caring for soldiers in battalion aid stations and troop medical clinics. The primary goal is heightened clinical awareness, leading to immobilization and prompt referral to supervising medical officers and specialty care when needed. Critical evaluation of the medical literature supports our proposal that a standardized approach to clinical examination would discriminate between soldiers requiring evaluation by the PA or physician and those for whom ADTMC guidelines for management apply. Our wrist injury protocol is summarized in the Appendix. Acknowledgments We thank Dr. Patrick D. Carroll for his cooperation and especially for his willingness to serve as an anatomical model. Appendix: Traumatic Wrist Injuries Purpose To provide guidelines for enlisted medical personnel evaluating soldiers with complaints of acute injury or chronic pain of the wrist. This should be used as augmentation to the ADTMC. The medic must be attentive to the significance of the mechanism of injury and the importance of a complete examination of the injured wrist. Subjective Data (Always Include) 1. Mechanism of injury (was mechanism from forced wrist extension and/or axial load, e.g., fall on the outstretched hand*, holding handlebars* or steering wheel* during MVA, or other high-energy trauma*?). Medics should note that wrist pain may be mild and even absent if the wrist is held motionless. 2. Wrist dominance (e.g., handedness). 3. Anatomical region of the wrist injured. 4. Pain (quality, radiation, severity, and timing). 5. History of prior wrist traumas. Objective Data (Record Vital Signs and Include) 1. Description of any gross deformity of the wrist. 2. Wrist ecchymosis and edema*, especially at the snuffbox. 3. Tenderness with palpation of the snuffbox*. 4. Tenderness with dorsal-radial wrist flexion/extension* or radial/ulnar deviation* or supination* or grip*. 5. Special tests, noting tenderness with palpation of the palmar scaphoid tubercle* or pain with longitudinal compression of the thumb*. Assessment 1. Cannot exclude fracture for any soldier meeting at least 1 criteria marked with an asterisk for mechanism of injury and physical examination results. Appropriate management is indicated; refer to plan. 2. Soft-tissue injury/sprain. Soldier does not meet any of the criteria. Refer to ADTMC. 3. Laceration. Soldier does not meet any of the criteria. Refer to ADTMC. 4. Abrasion. Soldier does not meet any of the criteria. Refer to ADTMC. 5. Chronic pain. Soldier does not meet any of the criteria. Refer to medical officer. Plan (Fracture Suspected) 1. A thumb-spica splint should be applied. 2. Rest, ice, compression, and elevation and nonsteroidal anti-inflammatory drugs should be used in accordance with standard operating procedures. 3. Dedicated X-rays of the wrist are required; the medical officer must be consulted. 4. Soldiers with positive X-rays should be referred to the orthopedic surgery service. 5. All soldiers with negative X-rays at initial evaluation should be maintained in the thumb-spica splint for 2 weeks. Follow-up evaluation at 2 weeks should include repeat examination using criteria described above. If physical examination findings are not completely resolved, then repeat X-rays should be obtained and the soldier should be referred to the orthopedic service. Alternative Pathway 1. As determined by the medical officer, soldiers with negative X-rays may alternatively undergo bone scanning at 72 hours after injury. 2. Soldiers with hot scans are referred to the orthopedic service immediately. 3. Soldiers with cold scans are changed to a removable splint and allowed to increase activity as tolerated. References U.S. Department of Defense: TRICARE Handbook, pp 1 8. Falls Church, VA, TRICARE Management Activity, 2004.

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