Use of CT-Arthrography and Ultrasound in ACL Surgery During Operation Enduring Freedom in Afghanistan: A Case Report and Practice Recommendations

ABSTRACT The availability of magnetic resonance imaging is severely limited in a deployed environment. However, advanced imaging for diagnosis and treatment of musculoskeletal soft-tissue injuries in theater does exist. Computed tomography (CT), arthrography, and ultrasound are readily available at Role 2 and 3 Medical Treatment Facilities in Afghanistan in support of Operation Enduring Freedom. In this report, we describe a case using CT arthrogram and ultrasound to assist with the diagnosis, treatment, and follow-up of an anterior cruciate ligament reconstruction surgery performed at a Role 2E hospital at Camp Arena, Herat, Afghanistan on a coalition soldier. All physicians who treat musculoskeletal injuries in theater should be familiar with the musculoskeletal applications of ultrasound and CT arthrography. Finally, treatment of the local population and coalition soldiers who do not have access to magnetic resonance imaging will be improved with the knowledge and use of existing advanced imaging in a deployed and austere setting.

INTRODUCTION

In December 2001, the U.N. Security Council approved the deployment of a peacekeeping force known as the International Security Assistance Force.1 North Atlantic Treaty Organization control of forces and logistics provides a unique opportunity to have U. S. Forces work in a joint and austere environment with other countries. Location, time, and equipment restraints make evaluating coalition soldiers and local nationals in this deployed environment challenging; for example, magnetic resonance imaging (MRI) assets are severely limited in theater.

However, computed tomography (CT) and ultrasound are readily available in theater. Today, musculoskeletal physicians in the United States use ultrasound in clinic on a regular basis to assess tendon integrity, rotator cuff pathology, abscess, infection, and placement of intra-articular injections. Ultrasound is also used to rule out deep venous thrombosis (DVT) in patients. CT with contrast (arthrogram) can be used when a patient has contraindications for MRI such as a pacemaker, dorsal column stimulator, metal fragments, or implants that may cause metallic scatter on MRI. CT arthrography carries the risks and problems of radiation and contrast allergic reaction. Provider experience and equipment limitations can make ultrasound readings difficult to interpret.

In a deployed environment, however, the benefits of these modalities outweigh the inherent risks for those patients who do not have access to an MRI. Ultrasound has shown prior utility in management of fractures in an austere environment to include natural disasters such as the Haiti earthquake relief effort in 2010.2,3 To date, no one has published the use of CT arthrogram in the austere environment for the diagnosis of musculoskeletal pathology.

In this article, we describe a case of a coalition soldier who sustained a noncontact knee injury at Camp Arena resulting in anterior cruciate ligament (ACL) insufficiency. CT arthrogram and ultrasound proved to be valuable tools in the diagnosis and management of this patient.4,5 Finally, we provide practice recommendations for the use of advance diagnostic imaging studies in an austere environment for soft-tissue musculoskeletal injuries.

CASE PRESENTATION

A 25-year-old coalition Infantry soldier presented to the Role 2E Medical Treatment Facility (MTF) at Camp Arena, Herat, Afghanistan with complaints of right knee instability and a moderate knee effusion. His medical history was significant for a prior noncontact knee injury sustained during soccer 1.5 years before presentation. He complained of recurrent and frequent knee instability despite nonoperative treatment to include physical therapy, bracing, and activity modification.

On physical examination, he had mildly decreased active and passive range of motion of his knee from 5^ to 120^ .A Thessaly test (active compression test) was painful and he had a grade 2B Lachman's test with guarding during the pivot-shift maneuver indicating an unstable knee.6,7 The posterior drawer test was negative and prone external rotation test was negative.8 His alignment was neutral. Our assessment was ACL insufficiency with possible meniscus injury. Radiographic studies did not show a Segond fracture.9,10 No MRI was available in theater and the coalition chain of command and soldier did not desire evacuation. Therefore, we performed a CT arthrogram of the knee after ultrasound images were nondiagnostic.5,11

METHODS

CT Arthrogram

After sterile skin preparation, the superior pole of the patella was palpated and an 18-gauge needle was placed into the suprapatellar recess of the right knee using a superior-lateral approach with the patient supine. Approximately 5 mL of bloody fluid was aspirated from the joint followed by injection of 35 mL iobitridol (Xenetix) 300 iodinated contrast. No other contrast was available. Following the intra-articular injection, the joint was subjected to active and passive range of motion to insure distribution of the contrast throughout the joint. No complications were observed during or after the procedure.12,13

The patient was placed in a supine position on the CT table with 0^ flexion at the knee. The CT study was performed with a 6-slice CT scanner using spiral technique. A frontal projection scout image was obtained followed by image acquisition from the right distal femoral metaphysis through the proximal tibial metaphysis. The scan was performed at 130 kVP, 80 mAs, and acquisition slice thickness of 0.63 mm. Transverse, sagittal, and coronal reconstructed images were obtained at 0.63 mm with utilization of standard soft-tissue and bony kernel algorithms.

Assessment of the CT arthrography images was consistent with ACL tear with no increased density in the menisci and no chondral filling defects or irregularity noted. CT arthrography coronal image shows mildly heterogeneous and irregular soft-tissue (solid arrows) at the lateral aspect of the interchondylar notch and contrast (open arrow) is seen between the inner aspect of the lateral femoral condyle and the posterior cruciate ligament (curved arrow) (Fig. 1). Sagittal CT image demonstrates an abnormal course and discontinuity of the ACL fibers (solid arrows) at the proximal footprint with contrast (open arrow) seen between the lateral femoral condyle and the posterior cruciate ligament (Fig. 2). Coronal CT image shows normal appearance of the medial and lateral menisci (open arrows). Chondral (solid arrows) filling defects are not seen (Fig. 3).12,13

Surgery

After informed consent obtained, the patient received approval from his command and he underwent a combined intraarticular and extra-articular ACL reconstruction with an autogenous iliotibial band graft using a mini-open technique with regional anesthesia similar to that used in Kocher et al14-17 (Fig. 4). The patient underwent standard ACL reconstruction postoperative protocol to include early weight bearing and range of motion exercises to decrease the low risk of DVT. The postoperative course was complicated by right leg swelling at 2 weeks. Ultrasound was negative for DVT 2 and 3 weeks after surgery. His swelling resolved and he had an uncomplicated recovery. During his follow-up visits, physical examination and ultrasound was used to confirm graft integrity.5,18 At 6 weeks, the patient returned to tower guard duty. At 6 months, his quadriceps strength and size had returned. He had a stable knee and was running without difficulty without complaints of instability.

DISCUSSION

Musculoskeletal soft-tissue diagnosis and treatment in an austere environment is difficult. In addition to the challenges of limited assets available at your facility level, both coalition soldiers and the local population may have unreasonable expectations regarding the level of care available. Traditionally, medical care in a war environment has been divided into an Echelon or Role system to improve treatment, triage, and evacuation. Role 1 MTFs provide effective unit primary care, first aid, triage, and emergency treatment in preparation for casualty evacuation.19 Role 2 MTFs provide unit primary and emergency care, specialty care to include surgery and intensive care support and beds. Role 2E (enhanced) MTFs also have advanced imaging to include CT, arthrography, and ultrasound.19,20 Role 3 MTFs offer theater of operations capability encompassing primary and specialist surgery, advanced imaging capabilities, and enhanced nursing capabilities.19,21 Role 4 hospitals provide "definitive care of patients for whom the treatment required is longer than the theater evacuation policy or for whom the capabilities usually found at role/echelon 3 are inadequate."19

Truax et al22 reviewed the incidence of musculoskeletal injuries during the Persian Gulf War. They found that softtissue injuries comprised 34% of the overall injuries in the Persian Gulf War, and twice as many patients required evacuation for diagnosis as were diagnosed locally using existing imaging modalities. They concluded that "a dedicated extremity magnetic resonance scanner in the battlefield would obviate many evacuations and hence be of both monetary and military readiness benefit."22 Although disease non-battle injury admission rates for Operation Enduring Freedom and Operation Iraqi Freedom are lower than those for Operation Desert Shield/Operation Desert Storm, the need for advanced imaging modalities still exists.23

Camp Arena, Herat, Afghanistan has a Role 2E Spanish hospital and the U. S. Army currently supports the hospital with an Orthopedic Surgeon, General Surgeon, Radiologist, Anesthesiologist, Internal Medicine physician, and Intensive Care Nursing and Tech support.20 The hospital provides trauma care, primary care, and musculoskeletal care. However, the hospital does not have MRI. U.S. soldiers, contractors, and coalition soldiers are usually evacuated when a physician determines an MRI is required for diagnosis. Currently, the United States will send soldiers to Landstuhl Regional Medical Center, a Role 4 hospital in Germany, for imaging and/or treatment for musculoskeletal injuries.

Some coalition soldiers and local nationals do not have the opportunity or the ability to be evacuated for diagnostic tests. In this case, our coalition patient was mission essential and his unit wanted him to have definitive treatment at our hospital. O'Shea et al24 showed that knee injuries do not require MRI if physical examination is diagnostic. However, we advocate the use of advance imaging studies to assist with surgery planning and to confirm the diagnosis if there is a diagnostic dilemma. In this case, the physical exam was consistent with ACL tear but meniscus injury could not be ruled out secondary to an inconclusive active compression test.6 A meniscus injury would lead to a more invasive surgery. Additional imaging needed to be done to evaluate the meniscus definitively and for preoperative planning. Multiple authors have shown that CT arthrography and ultrasound are viable alternatives to MRI for soft-tissue musculoskeletal injuries to include shoulder and knee pathology.4,5,18,25-29 At Camp Arena, CT arthrography and ultrasound were available and the radiologist was skilled in use of both modalities. The ultrasound images were nondiagnostic, secondary to the limitations of the machine available, for meniscus or ACL injury; therefore, a CT arthrogram was the modality of choice. Vande Berg et al11-13 have shown that the sensitivities and specificities for the detection of ACL tears using CT arthrogram were 90% and 96%, respectively; and the sensitivities and specificities for the detection of meniscal tears in knees with abnormal ACLs were 92% and 88%, respectively. The results of the CT arthrogram allowed the senior author to provide adequate informed consent and to perform an autograft ACL reconstruction with a mini-open incision without arthroscopic equipment in theater.14,15 In addition, ultrasound, although not helpful in this case with the diagnosis, in conjunction with nerve stimulation was used to decrease the amount of local anesthetic needed for regional anesthesia- femoral nerve block.30 Finally, ultrasound was used postoperatively successfully to rule out DVT and to assess graft integrity. Ultrasound postoperatively was more successful because of the graft placement that was more anterior in the surgery technique used and more readily accessible.

PRACTICE RECOMMENDATIONS

Unfortunately, many physicians rely on advanced imaging studies such as MRI for musculoskeletal diagnosis because of a lack of musculoskeletal education and examination skills.31 Despite the prevalence of musculoskeletal disorders in the United States and its military, physicians have received inadequate training during their training programs on how to examine, diagnose, and manage these conditions.32,33 The inability to correctly diagnose musculoskeletal conditions with physical examination has led to the overreliance and perceived need of MRI in the military leading to overuse of evacuation assets and increased costs.22 Almost all Role 2 MTFs have ultrasound and the enhanced (E) Role 2 MTFs and Role 3 MTFs have ultrasound and CT scan with capability of arthrography.

Medical students have already been successful in improving physical examination skills using ultrasound.34 We believe medical schools should also integrate ultrasound in medical education as part of a robust musculoskeletal program. The Uniformed Services University of the Health Sciences and the University of South Carolina currently use ultrasound in their teaching curriculum for physical examination to include musculoskeletal imaging.35,36 In addition, many orthopedic surgery residencies such as Dwight David Eisenhower Army Medical Center have ultrasound in their clinic to assist with diagnosis and physical examination. We recommend that military residency training programs that treat musculoskeletal conditions continue to incorporate the use of ultrasound in their programs to augment their physical exam skills.

Not all deployable radiologists are comfortable with the use of musculoskeletal ultrasound and CT arthrography. We recommend and encourage deploying radiologists to seek training opportunities in the musculoskeletal applications of ultrasound and CT arthrography before deployment. In addition, radiologists should be comfortable with contrast joint injections to assist with CT arthrography as the utility of ultrasound in diagnosing internal derangement of the knee in a deployed environment is variable.

In conclusion, the use of advanced imaging techniques currently available, such as ultrasound and CT arthrography, will decrease the need of MRI and reduce the number of evacuations for a diagnostic test. As CT and US technology continue to improve, the sensitivity and specificity of these tests will improve in theater. These imaging modalities will allow for advanced orthopedic surgical intervention as deemed necessary. Finally, treatment of the local population and coalition soldiers who do not have access to MRI will be improved with the use of existing advanced imaging in a deployed and austere setting.

ACKNOWLEDGMENT

We thank SPC Omar Wilson for giving us written permission to publish his knee drawing (Fig. 4).

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MAJ Patrick Davis, MC USA*; MAJ Justin J. Stewart, MC USA*; LTC(P) Nancy G. Hoover, MC USA*; MAJ Billie J. Matthews, AN USA*; Douglas W. Pahl, MD[dagger]; LTC(P) <person>John A. Bojescul, MC USA*

*Task Force 14th Combat Support Hospital Regional Command-West, Spanish Military Hospital (Role IIE), Camp Arena, Herat, Afghanistan APO AE 09382.

[dagger]Hughston Sports Medicine Clinic, 6262 Veterans Pkwy, Columbus, GA 31909.

The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.

doi: 10.7205/MILMED-D-13-00248