Skeletal imaging following reconstruction of the posterior cruciate ligament: in vivo comparison of fluoroscopy, radiography, and computed tomography

Preoperative Determination of the Size of the Semitendinosus and Gracilis Tendon by Multidetector Row CT Scanner for Anterior Cruciate Ligament Reconstruction

Accurately measuring the length and diameter of the hamstring tendon autograft preoperatively is important for planning anterior cruciate ligament (ACL) reconstructive surgery. The purpose of this study was to assess the reliability of three-dimensional computed tomography (3D CT) scanning technique to produce the actual measurement of the gracilis and semitendinosus (GT and ST, respectively) tendon grafts' length and diameter for surgery. Ninety patients were scheduled for ACL reconstruction with hamstring autograft. Before the surgery, patients were examined under the multidetector row CT scanner and the ST and GT tendons were qualitatively measured by a volume-rendering technique. The length of ST and GT was measured with 3D CT compared with the length of the harvested ST and GT. The cross-sectional area (CSA) of ST and GT measured with 3D CT compared with the ST and GT graft diameter. Tendon size measured preoperatively and during surgery were statistically compared and correlated. The GT tendons length and cross-sectional area measured during surgery was both shorter and smaller compared with the ST tendon. GT and ST tendon length were correlated to patients' body index such as the height and weight (p < 0.05). However, the correlation levels were low to medium (r = 0.23-0.49). There was strong correlation between the lengths of GT (r = 0.76; p < 0.001) and ST (r = 0.87; p < 0.001) measured with the 3D CT and tendon length at surgery. There was a moderate correlation between graft diameter measured at surgery and 3D CT cross-sectional area (r = 0.31; p < 0.05). A multidetector row CT scanner can determine the ST and GT tendons' length and diameter. These measurements can be used for preoperative planning to help determine the surgical method and counsel patients on appropriate graft choices prior to surgery.

Radiographic evaluation of the glenohumeral joint space in patients undergoing arthroscopic shoulder surgery in the beach-chair position

Background

Shoulder arthroscopy can be performed with the patient in the lateral decubitus or beach-chair position, but in both cases, glenohumeral (GH) joint spaces must be increased to improve visualization and allow access of the optical instrument. The aim of this study was to determine the effects of limb setup and longitudinal traction on the opening of the GH space with patients placed in the beach-chair (dorsal decubitus) position.

Methods

GH spaces at 3 test points corresponding to the anatomic locations of Bankart lesions were determined indirectly from radiographic images obtained from 67 patients presenting shoulder pathology with an indication for arthroscopic surgery. Measurements were made with the operative limb in neutral rotation and positioned in relation to the coronal plane in adduction, 45° of abduction, or adduction with an axillary spacer, in each case with and without longitudinal traction.

Results

GH spaces were optimized at 2 of 3 test points when the operative limb was positioned in adduction or neutral rotation and manual longitudinal traction was applied with or without a polystyrene spacer placed under the axilla, but use of the spacer was essential to maximize the GH space at all 3 locations. In contrast, 45° of abduction proved to be the least appropriate position because it afforded the smallest GH space values with or without traction.

Conclusion

Appropriate positioning of the patient on the operating table is a critical aspect of shoulder arthroscopy. Radiographic images revealed that adducted upper-limb traction with the use of an axillary spacer in patients in the beach-chair position generates a significant increase in the GH space in the lower half of the glenoid cavity, thereby facilitating visualization and access of the optical equipment to the GH compartments.

Measurements of tunnel placements after anterior cruciate ligament reconstruction--A comparison between CT, radiographs and MRI

BACKGROUND

A non-anatomic placement of the femoral and tibial tunnels may affect outcome in anterior cruciate ligament (ACL) reconstructions. Tunnel placements are validated with varying imaging modalities. We compared measurements of tunnel placements between radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) in a clinical setting, assessed the reliability and aimed to decide on a possible "gold standard".

METHODS

All patients who had undergone at least two of three modalities, radiographs, MRI and CT, after ACL reconstruction between January 2011 and June 2013 were included. Two radiologists measured tunnel placements according to a standardized protocol. Interobserver agreement was assessed with intraclass correlation coefficients (ICC), the intermodality differences with Bland-Atman plots. Radiation data for CT studies were collected.

RESULTS

Forty-six CTs, 45 radiographs and 30 MRIs were reviewed. Femoral inter-observer agreement for radiographs was ICC=0.64, for CT ICC=0.86 and for MRI ICC = 0.75. Tibial inter-observer agreement for radiographs was ICC=0.92, for CT-mip ICC=0.91, for CT and MRI ICC = 0.87. No intermodality differences between the femoral measurements were observed. In the tibia, there were differences between radiographs and CT (-3.9%), radiographs-MRI (-3.6%), CT-CT mip (3.2%) and CTmip-MRI (-3.1%). The effective radiation doses varied between 0.025 and 0.045 mSv, mean and median was 0.033 mSv.

CONCLUSION

There were differences in the tibial measurements between summation and single slice images. Only 3D-CT depicted the femoral tunnel in both directions. CT was consistently reliable in both femoral and tibial measurements. Effective radiation dose from CT was lower than previously reported. CT can safely be used in routine clinical practice to evaluate tunnel placements after ACL reconstruction.