Jeroen Vanhaecke

Accuracy of 3D Virtual Planning of Corrective Osteotomies of the Distal Radius

Corrective osteotomies of the distal radius for symptomatic malunion are time-tested procedures that rely on accurate corrections. Patients with combined intra- and extra-articular malunions present a challenging deformity. Virtual planning and patient-specific instruments (PSIs) to transfer the planning into the operating room have been used both to simplify the surgery and to make it more accurate. This report focuses on the clinically achieved accuracy in four patients treated between 2008 and 2012 with virtual planning and PSIs for a combined intra- and extraarticular malunion of the distal radius. The accuracy of the correction is quantified by comparing the virtual three-dimensional (3D) planning model with the postoperative 3D bone model. For the extraarticular malunion the 3D volar tilt, 3D radial inclination and 3D ulnar variance are measured. The volar tilt is undercorrected in all cases with an average of -6 ± 6°. The average difference between the postoperative and planned 3D radial inclination was -1 ± 5°. The average difference between the postoperative and planned 3D ulnar variances is 0 ± 1 mm. For the evaluation of the intraarticular malunion, both the arc method of measurement and distance map measurement are used. The average postoperative maximum gap is 2.1 ± 0.9 mm. The average maximum postoperative step-off is 1.3 ± 0.4 mm. The average distance between the postoperative and planned articular surfaces is 1.1 ± 0.6 mm as determined in the distance map measurement. There is a tendency to achieve higher accuracy as experience builds up, both on the surgeons side and on the design engineering side. We believe this technology holds the potential to achieve consistent accuracy of very complex corrections.

Influence of wrist position on maximum grip force in a post-operative orthosis.

Background: Flexor tendon repair in the hand remains challenging in avoiding tendon rupture and adhesion formation. Post-operative mobilization has been shown to be critical in regaining functional range of motion. Objectives: The objective of this study is 2-fold: to assess the influence of wrist position on maximum grip force generated in a post-operative orthosis and to determine the correlation between this maximum grip force and an individual’s grip strength. Study design: Clinical measurement Methods: A total of 30 uninjured wrists of right-handed men were given a post-operative orthosis with an incorporated Caroli-hinge. The maximum grip force was measured according to a different wrist position ranging from −30° extension until 80° of flexion using a 10° interval. These measurements were plotted out on a graph for regression analysis. A correlation was determined between measurements in a neutral wrist position and maximum grip strength generated without an orthosis. To assess the coherence of the measurements, a mean intraclass correlation coefficient was used. Results: The maximum grip force values were statistically significantly different in every wrist position and decreased progressively with an increasing flexion angle (p < 0.05). This relationship is expressed in a logistic regression curve f(x) = −4.98 + 16.92/(1 + (x/8.59))2.24. A wrist position of 4.4° of flexion was derived from this function to cause a maximum grip force reduction of 33%. Further analysis showed a force decrease of 50% at 23.2° and 66% at 51.8° of wrist flexion. The grip strength measured without an orthosis showed a positive correlation with previous measurements (Spearman’s correlation coefficient = 0.74 for the right hand and 0.72 for the left hand (p < 0.001)). Conclusions: The obtained logistic function allowed to derive the wrist position needed in a post-operative orthosis to obtain a desired amount of maximum grip force reduction. Clinical relevance Measuring a high grip force in a clinical setting of flexor tendon repair on the contralateral non-affected hand could indicate the use of an increased flexion angle in a post-operative orthosis. This reduces the load transferred on the tendon repair when involuntary contractions take place, for example, during sleeping when positioned in a post-operative orthosis.

Trapeziometacarpal stabilization through dorsoradial ligament reconstruction: An early post-surgery in vivo biomechanical analyses: TRAPEZIOMETACARPAL STABILIZATION THROUGH DORSORADIAL LIGAMENT

Ligament reconstruction can provide pain relief in patients with a painful, unstable, pre‐arthritic trapeziometacarpal (TMC) joint. Imbrication of the dorsoradial ligament (DRL) has been proposed as a minimal invasive stabilization technique. It requires less invasive surgery than an Eaton‐Littler technique and shows promising long‐term clinical outcome. We used dynamic CT to objectively review the effects of the imbrication. Four patients with pain and laxity at the TMC joint, but without radiographic signs of osteoarthritis, were recruited. Dynamic CT scans were made during active thumb abduction‐adduction, flexion‐extension, and two functional grip tasks using a radiolucent jig. Scans of the patients were acquired before and 3 to 6 months after DRL reconstruction. Motion of each bone in the articular chain of the thumb was quantified. In addition, we mapped changes in the contact patterns between the articular facets during the entire thumb motion. After DRL imbrication, we found no overall decrease in MC1 movement in three out of four patients. Furthermore, no increase in TMC joint congruency, defined as proximity area size, was found for three out of four patients. Pre‐ and post‐operative differences in congruency across different tasks were patient‐dependent and relatively small. We demonstrated that, from a biomechanical perspective, there is high variability in post‐operative outcome between patients that undergo identical surgical procedures performed by the same surgeon. A post‐operative decrease in range of motion, increase in joint congruency or decrease in proximity area shift during thumb motion is not omnipresent.

Airbag-induced thumb avulsion: two case reports.

Although airbags are designed to save lives and protect victims from serious injuries, airbag deployment can cause unwanted lesions. In this case report, two cases are presented of young women who sustained an important fracture dislocation of the first carpometacarpal joint (CMC I joint) caused by airbag deployment during a car collision.