The Journal of Foot & Ankle Surgery xxx (2015) 1–5

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Original Research

Assessment of Postoperative Tendon Quality in Patients With Achilles Tendon Rupture Using Diffusion Tensor Imaging and Tendon Fiber Tracking Hakan Sarman, MD 1, Halil Atmaca, MD 2, Ozgur Cakir, MD 3, Umit Sefa Muezzinoglu, MD 4, Yonca Anik, MD 5, Kaya Memisoglu, MD 6, Tuncay Baran, MD 7, Cengiz Isik, MD 1 1

Assistant Professor, Department of Orthopedics and Traumatology, Abant Izzet Baysal University School of Medicine, Bolu, Turkey Assistant Professor, Department of Orthopedics and Traumatology, Akdeniz University School of Medicine, Antalya, Turkey Radiology Specialist Physician, Department of Radiology, Ministry of Health Batman Regional Hospital, Batman, Turkey 4 Professor, Department of Orthopedics and Traumatology, Kocaeli University School of Medicine, Kocaeli, Turkey 5 Professor, Department of Radiology, Kocaeli University School of Medicine, Kocaeli, Turkey 6 Associate Professor, Department of Orthopedics and Traumatology, Kocaeli University School of Medicine, Kocaeli, Turkey 7 Resident Physician, Department of Orthopedics and Traumatology, Kocaeli University School of Medicine, Kocaeli, Turkey 2 3

a r t i c l e i n f o

a b s t r a c t

Level of Clinical Evidence: 4

Although pre- and postoperative imaging of Achilles tendon rupture (ATR) has been well documented, radiographic evaluations of postoperative intratendinous healing and microstructure are still lacking. Diffusion tensor imaging (DTI) is an innovative technique that offers a noninvasive method for describing the microstructure characteristics and organization of tissues. DTI was used in the present study for quantitative assessment of fiber continuity postoperatively in patients with acute ATR. The data from 16 patients with ATR from 2005 to 2012 were retrospectively analyzed. The microstructure of ART was evaluated using tendon fiber tracking, tendon continuity, fractional anisotropy, and apparent diffusion coefficient values by way of DTI. The distal and proximal portions were measured separately in both the ruptured and the healthy extremities of each patient. The mean patient age was 41.56  8.49 (range 26 to 56) years. The median duration of follow-up was 21 (range 6 to 80) months. The tendon fractional anisotropy values of the ruptured Achilles tendon were significantly lower statistically than those of the normal side (p ¼ .001). However, none of the differences between the 2 groups with respect to the distal and proximal apparent diffusion coefficient were statistically significant (p ¼ .358 and p ¼ .899, respectively). In addition, the fractional anisotropy and apparent diffusion coefficient measurements were not significantly different in the proximal and distal regions of the ruptured tendons compared with the healthy tendons. The present study used DTI and fiber tracking to demonstrate the radiologic properties of postoperative Achilles tendons with respect to trajectory and tendinous fiber continuity. Quantifying DTI and fiber tractography offers an innovative and effective tool that might be able to detect microstructural abnormalities not appreciable using conventional radiologic techniques. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.

Keywords: Achilles tendon rupture diffusion tensor imaging fractional anisotropy surgery tendon fiber continuity trauma

The Achilles tendon (AT) is ruptured more frequently than any other tendon and accounts for 40% to 60% of all operative tendon repairs, with 75% of these procedures stemming from AT rupture (ATR) due to sports-related activities (1–3). Patients with ATR will mainly experience a long-term period of rehabilitation and regaining

Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Hakan Sarman, MD, Department of Orthopedics and Traumatology, Abant Izzet Baysal University School of Medicine, Golkoy, Bolu 14280, Turkey. E-mail address: [email protected] (H. Sarman).

full physical activity is dependent on tendon healing. Although many studies have reported the clinical outcomes of ATR treatment using various scores and questionnaires (2,4–7), none have provided any information about tendon healing in terms of the microstructural characteristics. In previous studies, ultrasonography and magnetic resonance imaging (MRI) have been used to diagnose ATR (8–10). Ultrasonography and MRI have also been used to monitor the healing process after ATR (11), quantifying the thickness and structure of the tendon but not the quality of the repair process (10,12). Diffusion tensor imaging (DTI), which is a specialized form of MRI scanning, has been evaluated as a noninvasive technique for

1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.12.025

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describing the microstructural characteristics and organization of anisotropic tissues (eg, skeletal and cardiac muscles fibers, brain, spinal cord, and kidney) by way of directionality (13–16). As such, DTI and fiber tractography offer an innovative and powerful tool that might be capable of detecting microstructural abnormalities not perceivable using conventional MRI techniques (13,17). We hypothesized that it would be possible to observe the postoperative tendon quality with respect to fiber continuity and cell viability using DTI. The aim of the present study was to evaluate the microstructure of the ruptured AT using tendon fiber tracking, tendon continuity, fractional anisotropy, and apparent diffusion coefficient values through DTI. The main difference between the present study and previous studies was the unique evaluation of the tendon microstructure using DTI.

Patients and Methods Patient Population The data from 16 patients, including 3 females (18.75%) and 13 males (81.25%), with acute ATR, who had been treated from January 2005 to December 2012, were retrospectively analyzed. Because the DTI results could have been affected by the type of treatment, such as minimally invasive, open, or nonsurgical interventions, only those patients who had undergone the same treatment were enrolled in the present study. Thus, to be included, all the patients had to have undergone closed surgical repair of their ATR (18). In addition, only patients with a unilateral ATR were included. Finally, all the patients had to have undergone DTI MRI 6 months after surgery. Each participant served as their own control. Specifically, the study group included the lower extremity with ATR, and the control group included the lower extremity without ATR (the healthy extremity). Therefore, to be included, each participant’s uninjured lower extremity had to be free of rupture or any other clinical evidence of tendinopathy.

MRI Protocol MRI was performed with a 3-Tesla scanner (Achieva InteraÔ, release 2.3.6.7; Philips Healthcare, Eindhoven, The Netherlands) using a transmit-receive head coil with the patient in the standard supine position and resting the leg. The routine ankle MRI protocol in our department included axial, sagittal, and coronal T1-weighted turbo-spin echo (repetition time [TR]/excitation time [TE] 569 ms/25 ms), axial proton densityweighted (TR/TE 7506 ms/30 ms), coronal T2-weighted turbo-spin echo (TR/TE 6470 ms/100 ms), and coronal short T1-weighted inversion recovery (TR/TE 7985 ms/55 ms) sequences. The diffusion tensor images were acquired with bilateral, axial, single-shot, turbo spin-echo echo-planar imaging sequence (TR/TE 14,447 ms/55 ms; echo-planar imaging factor 68; sense factor 2; matrix 98  132; slice thickness 2 mm with no gap; field of view 191  230 mm; 15 directions) acquired using b values of 0 and 1000 s/ mm2. The total imaging time was 16 to 18 minutes (DTI 1 minute 48 seconds). All MRI acquisitions were visually checked for artifacts before processing. Image Analysis Quantitative analyses were performed using a dedicated workstation (release 2.5.3.0; Philips Medical Systems, Best, The Netherlands). All images were assessed by 2 radiologists (O.C., Y.A.), and every treating surgeon contributed to the evaluation of the results. The final decision was by consensus. For the measurements of the mean diffusivity and fractional anisotropy (FA), the localization of the regions of interest was also determined by consensus. For quantitative analysis of DTI and FA, maps were created automatically by the imaging console. The mean diffusivity and FA values from DTI were measured on the apparent diffusion coefficient (ADC) map with b values of 0 and 1000 s/mm2. The measurements were performed by placing the regions of interest to the proximal and distal parts of the normal and ruptured ATs. The region of interest was carefully placed on the proximal-distal tendon to include the largest possible volume without including necrotic, hemorrhagic, or cystic components. The measurements were repeated twice, and the mean average was recorded as the final result. Data Analysis Postprocessing was performed at another workstation (release 2.5.3.0 2007-12-03; Philips Medical Systems). The DTI measurements were performed over the AT with the

Fig. 1. Diffusion tensor imaging of the normal Achilles tendons. ADC1, apparent diffusion coefficient of distal part of musculotendinous junction; ADC2, apparent diffusion coefficient of proximal part of musculotendinous junction; FA1, distal fractional anisotropy; FA2, proximal fractional anisotropy.

H. Sarman et al. / The Journal of Foot & Ankle Surgery xxx (2015) 1–5

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Table 1 Results of DTI measurements and comparisons between normal and ruptured tendons (N ¼ 16 patients) Variable

Normal Tendon Side (n ¼ 16 tendons)

FA1 FA2 ADC1 ADC2

0.62 0.62 1.09 1.10

   

0.13 0.14 0.26 0.26

Ruptured Tendon Side (n ¼ 16 tendons) 0.43 0.43 1.19 1.11

   

0.12 0.12 0.31 0.35

p Value

Assessment of Postoperative Tendon Quality in Patients With Achilles Tendon Rupture Using Diffusion Tensor Imaging and Tendon Fiber Tracking.

Although pre- and postoperative imaging of Achilles tendon rupture (ATR) has been well documented, radiographic evaluations of postoperative intratend...
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