After a fracture of the distal radius, the bone segments may heal in a suboptimal position. This condition may lead to a reduced hand function, pain and finally osteoarthritis, sometimes requiring corrective surgery.

The contralateral unaffected radius is often used as a reference in planning of a corrective osteotomy procedure of a malunited distal radius. In the conventional procedure, radiographs of both the affected radius and the contralateral radius have been used for planning. The 2D nature of radiographs renders them sub-optimal for planning due to overprojection of anatomical structures. Therefore, computer-assisted 3D planning techniques have been developed recently based on CT images of both forearms.

The accuracy of using the contralateral forearm for CT based 3D planning the surgery of the affected arm and the optimal strategy for planning have not been studied thoroughly.

To estimate the accuracy of the planned repositioning using the contralateral forearm we investigated bilateral symmetry of corresponding radii and ulnae using 3-dimensional imaging techniques. A total of 20 healthy volunteers without previous wrist injury underwent a volumetric computed tomography scan of both forearms. The left radius and ulna were segmented to create virtual 3 dimensional models of these bones. We selected a distal part and a larger proximal part from these bones and matched them with a mirrored CT-image of the contralateral side. This allowed estimation of the accuracy by calculation of relative displacements (Δx, Δy, Δz) and rotations (Δψx, Δψy, Δψz) required to align the left bone with the right bone segments as a reference. We also investigated the relationship between longitudinal length differences in radius and ulna and utilised this relationship to arrive at an optimal planning of the length of the affected radius after surgery.

Relative differences in displacement and orientation parameters after planning based on the contralateral radius were (Δx, Δy, Δz): −0.81±1.22 mm, −0.01±0.64 mm, and 2.63±2.03 mm; and (Δψx, Δψy, Δψz): 0.13°±1.00°, −0.60°±1.35°, and 0.53°±5.00°. The same parameters for the ulna were (Δx,Δy, Δz): −0.22±0.82 mm, 0.52±0.99 mm, 2.08±2.33 mm; and (Δψx, Δψy, Δψz): −0.56°±0.96°, −0.71°±1.51°, and −2.61°±5.58°. The results also point out that there is a strong linear relationship between absolute length differences (Δz) of the radius and ulna among the individuals.

Since we observed substantial length difference of the longitudinal bone axes of both forearms in healthy individuals, including the length difference of the adjacent forearm bones in the planning turned out to be useful in improving length correction in computer-assisted planning of radius or ulna osteotomies. The improved planning markedly reduces length positioning variability, (from 2.9± 2.1 mm to 1.5 ± 0.6 mm). We expect this approach to be valuable for 3-D planning of a corrective distal radius osteotomy. Awareness of the level of bilateral symmetry is important in reconstructive surgery procedures when the contralateral unaffected side is used as a reference for planning and evaluation. Bilateral asymmetry may introduce length errors into this type of preoperative planning that can be reduced by taking into account the concomitant ulnae asymmetry.

A fracture of the distal radius may lead to malunion of bone segments, which gives discomfort to the patient and may lead to chronic pain, reduced range of motion, reduced grip strength and finally to early osteoarthritis. A treatment option to realign the bone segments is a corrective osteotomy. In this procedure the surgeon tries to improve alignment by cutting the bone at, or near, the fracture location and by fixating the bone segments in an improved position, using a plate and screws. Standard corrective osteotomy of the distal radius is most often planned using two orthogonal radiographs to find correction parameters for restoring the radial inclination, palmar tilt and ulnar variance, to normal. However, 2D imaging techniques hide rotations about the bone axis and may therefore cause a misinterpretation of the correction parameters.

We present a new technique that uses preoperative 3-D imaging techniques to plan positioning and to design a patient-tailored fixation plate that only fits in one way and realigns the bone segments as planned in six degrees of freedom. The procedure uses a surgical guide that snugly fits the bone geometry and allows predrilling the bone at specified positions, and cutting the bone through a slit at the preoperatively planned location. The patient-tailored plate fits the same bone geometry and uses the predrilled holes for screw fixation. The method is evaluated experimentally using artificial bones and renders realignment highly accurate and very reproducible (d_err < 1.2 ± 0.8 mm and ϕ_err < 1.8 ± 2.1°). In addition, the new method is evaluated clinically (n=1) and results in accurate positioning (d_err ≤ 1.0 mm and ϕ_err ≤ 2.6°).

Besides using a patient-tailored plate for corrective distal radius osteotomy, the method may be of interest for corrective osteotomy of other long bones, mandibular reconstruction and clavicular reconstruction as well. In all of these cases the contralateral side can equally be used as reference for reconstruction of the affected side.

The two-step method of predrilling and cutting using a surgical guide, followed by the utilisation of a patient-tailored plate for fixation and accurate 3D positioning at the same time, seems very easy to utilise during surgery, since it does not require complex navigation, robotic equipment or tracking tools. Custom treatment with a patient-tailored plate may reduce the reoperation rate, since repositioning is likely to be better than conventional malunion treatment using 2D imaging techniques and a standard anatomical plate. The patient-tailored plating technology is expected to have a great impact on future corrective osteotomy surgery.

Purpose: Presently, tension band figure-of-eight fixation of olecranon fractures is usually performed with stainless steel wire. A polyethylene cable cerclage has been proposed as an alternative to lessen the complications associated with wire. This study compared the stability of tension band constructs for olecranon fracture fixation using a polyethylene cable cerclage or a stainless steel wire cerclage.

Methods: Ten matched pairs of fresh-frozen cadaveric elbows, without radiographic abnormality, were selected for the study. In each specimen, a transverse fracture was created by an osteotomy at the middle of the sigmoid notch of the olecranon. One elbow of each pair was randomized for tension band fixation with a figure-of-eight construct while the other was fixed by tension banding with a loop cerclage. Two different materials, stainless steel wire and isoelastic polyethylene cable, were randomly selected to create the cerclage constructs in each elbow. The triceps tendon was controlled and cyclic loads were applied to the dorsal cortex of the ulna 8 cm distal to the fracture site to create a bending moment. The elbow was initially preconditioned at 45 N for 100 cycles, followed by four periods of 300 cycles each, from 45 N to 120 N in 25 N increments. Dynamic and static fracture gap for the different configurations and materials were recorded.

Results: No difference in static gap was found between the metal figure-of-eight, cable figure-of-eight and cable loop constructs (p> 0.05). The metal loop was found to have significantly greater gap (p=0.0013) than the other 3 constructs. No difference was observed in dynamic gap at the peak loads for any of the constructs (p=0.3379).

Conclusion: This study demonstrated that the biomechanical performance of tension band fixation in an olecranon fracture model using a polyethylene cable in either figure-of-eight or loop construct is similar to that of the stainless steel wire figure-of-eight construct and should be considered as an option to the traditional stainless steel wire. This type of soft and tissue tolerant fixation may lessen the known clinical complications of wire fixation while providing equivalent stability under physiologic loads which would permit early rehabilitation.