Fig 1.
Influence of tendon length by graft fixation in 40° and 90°.
Considering that the radial tuberosity moves along a radius of 5cm relative to the center of rotation (COR) of the elbow, an allograft tendon refixation with same traction in 40° (red forearm) compared to 90° (violet forearm) of elbow flexion may lead to a shortening of 4cm, representing almost 60% of the original distal biceps tendon length.
Table 1.
Demographics.
Fig 2.
a) Manual segmentation of the distal biceps tendon, proximal radial bone and distal muscle belly of the brachial biceps. b) Generation of 3D surface models: Three examples.
Fig 3.
3D tendon length measuring from the distal myotendinous junction to the insertion on the bicipital tuberosity: a) Tendon insertion (radial tuberosity): The first sphere was placed on the tendon insertion, centered on the radial tuberosity. b) Tendon course: 4–8 further spheres were placed along the entire tendon, wherever the tendon changed the direction. c) Tendon origin (muscle belly): The last sphere was placed at the distal myotendinous junction. d) Tendon length measuring: The tendon length was measured as the distance of the center of the sphere 1–2 + 2–3 + 3–4 + 5–6 + 6–7.
Fig 4.
Inter-epicondylar distance (IED) and radial head diameter (RHD).
IED = inter-epicondylar distance: Measured from the medial to the lateral epicondyle. RHD = radial head diameter: Measured as the diameter of the radial head, perpendicular to the radial head surface.
Fig 5.
This histogramm shows the distribution of the tendon length in general (yellow curve; mean value of 69mm), in women (violett; mean value of 64mm) and in men (blue; mean value of 71mm).
Table 2.
Basic dimensions.
Table 3.
Measurments and correlations in dependence of gender and side.
Fig 6.
Distal biceps tendon length prediction by.
This histogram shows the tendon length prediction by mean tendon length (TL; mean value 69mm), mean tendon length with gender distinction (TL; F Female mean value 64mm, M Male mean value 71mm), patient’s heigth (PH in cm x0.4), inter-epicondylar distance (IED in mm x1.1) and radial head diameter (RHD in mm x3). The scale reaches from 0 to -30mm (left) and +30mm (right). Perfect match would be a value of 0. And positive values imply that the calculated tendon assumes a too long, negative values too short. For example, the calculated tendon by RHD tends to be rather longer (23 elbows >+0.5cm) than smaller (16 elbows <-0.5cm).
Table 4.
Distal biceps tendon length prediction by.
Fig 7.
Surgical technique for distal biceps tendon auto-/allograft length adjustment.
a) Tendon graft: Both graft ends are reinfored by #2 FiberWire. The bone tunnel length (mark 1) and calculated tendon length without the remaining tendon stump (mark 2) are marked on the graft. b) Tendon graft fixation distally: The tendon graft is first fixed distally and shuttled through the biceps tunnel. After that, the sutures are penetrated throught the remaining tendon with a sharp suture grasper clamp. c) Tendon length adjustment: The elbow is flexed as far as needed and the graft tensionned, until the marker is flash with the remaining tendon end. A slide back of the tendon is preventionned by some sutures (#2 Vicryl). d) Tendon graft fixation proximally: The graft is interwaved through the remaining tendon–two to three times, depending on graft length–and finally knotted together. Further sutures (#2 Vicryl) are performed.
Fig 8.
Intraoperative pictures of graft interposition with a hamstring autograft.
a) Green = calculated tendon length, White = calculated tendon length without remaining tendon stump, Pink = intraosseous distance of 0.5cm. Mark 1 = corresponding to intraosseous distance, Mark 2 = corresponding to calculated tendon length without remaining tendon stump. b) The arm is flexed, mark 2 visible. c) Tendon length adjustment. d) Interwave of the autograft.