3D C-arm navigated acromioclavicular joint stabilization

Abstract

Introduction: Surgical treatment options for acromioclavicular joint separations are varied. Frequently, suspension devices (SD) are inserted for stabilization under arthroscopic view. This study investigates the feasibility and accuracy of three-dimensional (3D) digital-volume-tomography (DVT) C-arm navigated implantation with regard to the general trend toward increasingly minimally invasive procedures.

Materials and methods: The implantation of a TightRope^® suture button system (SD) via a navigated vertical drill channel through the clavicle and coracoid was investigated in 10 synthetic shoulder models with a mobile isocentric C-arm image intensifier setup in the usual parasagittal position. Thereby, in addition the placement of an additive horizontal suture cerclage via a navigated drill channel through the acromion was assessed.

Results: All vertical drill channels in the Coracoclavicular (CC) direction could be placed in a line centrally through the clavicle and the coracoid base. The horizontal drill channels in the Acromioclavicular (AC) direction ran strictly in the acromion, without affecting the AC joint or lateral clavicle. All SD could be well inserted and anchored. After tensioning and knotting of the system, the application of the horizontal AC cerclage was easily possible. The image quality was good and all relevant structures could be assessed well.

Conclusion: Intraoperative 3D DVT imaging of the shoulder joint using a mobile isocentric C-arm in the usual parasagittal position to the patient is possible. Likewise, DVT navigated SD implantation at the AC joint in CC and AC direction on a synthetic shoulder model. By combining both methods, the application in vivo could be possible. Further clinical studies on feasibility and comparison with established methods should be performed.

Keywords: 3D C-arm navigation; AC joint separation; Rockwood; Shoulder imaging; Tightrope; Tossy.

Fig. 1

System setup in the operating room. a–c a synthetic shoulder model is attached to the operating table. The mobile C-arm is placed in parasagittal position at the head end. The navigation camera is pointed at the references on the model and the C-arm. The navigation monitor still shows images of the first DVT scan with a planned CC drill channel. On the X-ray monitor, the already implanted SD is visible in two planes. The drill, wires, and pointers are on the instrument table. d–e the planning of the navigated drill channel in CC direction is shown enlarged in two planes (coronal and sagittal)

Fig. 2

Navigated drilling and implantation of the SD. a the reference is attached to the lateral acromion margin, temporarily fixing the AC joint and the CC drill channel is already being prepared with a lying drill wire. b the AC drill channel is created. c the drill wire in the acromion is replaced by a wire loop through which the suture loop is pulled later. d the lying CC drill wire is overdrilled using a cannulated drill. e a trocar is introduced CC. f the SD is inserted through the trocar. g the SD is anchored below the coracoid and above the clavicle. h the SD is knotted and then a thread end will be pulled laterally through the acromion using the wire loop

Fig. 3

Illustrated in a sketch. Shown is the arrangement of the mobile C-arm and navigation camera to the shoulder models on the operating table in the center. Surgeon (OP), assistant (ASS), nurse, anesthesia (AN), and monitors around. The area marked in red represents the imaged body region (right shoulder with complete AC joint) between the X-ray tube and detector of the C-arm

Fig. 4

Intraoperative DVT images of the examined models for control and measuring of the inserted SD in multiplanar view (a–d) and 3D reconstruction (e–g). a Sagittal plane to measure the position and length (dashed line) of the CC drill channel and assess the button position above the clavicle and below the coracoid (here the drill channel is centered in the clavicle and the lower button is directly at the tip of the coracoid arch at 12 o’clock) directly on the bone. b Coronal plane for measuring and evaluating the CC and AC drill channel as well as the button position (the central position of the CC drill channel and the button placed directly underneath the coracoid as well as the correctly positioned wire loop in the AC drill channel without affecting the lateral clavicle are confirmed here). c Axial plane to evaluate the central position of the drill channel entrance at the surface of the clavicle (yellow parallel lines) as well as the distance from here to the lateral end of the clavicle (orange dashed line) as well as the direction of the AC drill channel (gray dashed line from the wire loop to the center of the drill hole). d Axial plane at the level of the coracoid surface to determine the central drill channel position in anterior–posterior and medial–lateral direction (yellow grid lines). e and f 3D reconstruction in the direction of view from medioventral and cranioventral for three-dimensional assessment of the AC joint position (acromion = one star, lateral clavicle = two stars and coracoid = three stars) and the implant position (inserted wire loop in the AC drill channel, attached button above the clavicle and below the coracoid). g Hard paned 3D image reconstruction with direct view to the two CC titanium buttons from cranial to caudal