Authors (including presenting author) :
Mak MCK(1), Ho PC(1), Tse WL(1), Yu FWP(1)
Affiliation :
Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong
Introduction :
Distal radius malunion is a common complication after distal radius fractures and has been reported in up to 76% of patients after nonoperative treatment of distal radius fractures. Malunion, if significant, may affect joint loading, kinematics, and stability of the wrist and distal radioulnar joints. These can give rise to pain, limitation in range of motion, functional limitation, and deformity, particularly in patients with high functional demand or in the working population. Specifically, shortening of the radius leads to increase in ulnocarpal joint loading and ulnar impaction syndrome, incongruence of the radiocarpal and distal radioulnar joints may lead to arthritis and motion impingement, and abnormal joint angulation may lead to carpal instability. Corrective osteotomy of the distal radius aims to restore normal skeletal anatomy and relieve symptoms caused by the malalignment. However, accurate correction in all three planes may be difficult to achieve by conventional surgical planning, based on assessment from biplanar radiographs. On-table assessment is time consuming and is often inaccurate due to positional factors. Three-dimensional planning based on computed tomography images has been advocated, and the osteotomy and screw holes can be guided by 3D printed patient-specific guides. With this technique, reduction is performed by fixing the plate on pre-planned screw holes, and using a precisely fashioned bone graft that restores alignment after being fitted into the defect. However, this process depends on manual repositioning of the fragments until the plate holes exactly match those drilled in the bone, which may be difficult. Also, only one implant could be used and cannot be changed. To facilitate the realignment of the two fragments, we developed a reduction guide which holds the fragments in position while fixation is performed in the similar fashion as simple distal radius fracture.
Objectives :
This study was performed to demonstrate the feasibility and accuracy of 3D printed osteotomy and reduction guides in the surgical treatment of distal radius malunions. This is done by assessment of the accuracy of correction in terms of radiological outcomes, complications of surgery, functional outcomes, and symptom relief.
Methodology :
A retrospective review of all patients with extra-articular distal radius malunion treated by corrective osteotomy using rapid prototyping since 2016 to 2021 was done. Pre-operative computed tomography was performed, and planning was done using 3D imaging software (3matic, Mimics). Opening wedge osteotomies were performed using patient-specific cutting guides, and a novel reduction guide was designed in which a three-dimensionally pre-planned guide fitted into the osteotomy site so that the two fragments are realigned to exactly match the anatomy of the contralateral normal radius. Bone graft or bone substitutes were used to fill into the gap after plate fixation was performed. Ulnar shortening osteotomy was performed when ulnar variance was positive despite adequate correction of the radius as planned or if excessive lengthening >1.5cm of the radius was required. Outcome measurements included radiological and functional parameters. In all cases, radiological parameters including ulnar variance, tilting of the distal articular surface, and radial inclination were measured. In cases in which computed tomography was performed for assessing bony union, matching of the distal articular surface was performed by software (3matic). Functional assessment included pain VAS score, range of motion, grip strength, wrist performance scores, and DASH score.
Result & Outcome :
A total of 6 patients were treated by this method from 2015 to 2021, with an average follow up of 2.5 years. 5 cases involved bone grafting and in one case, bone substitute was used. 4 cases resulted in successful bone union, and 1 patient received surgery less than 4 weeks ago to have assessment of union. All reported improvement in their VAS, wrist performance scores, pain scores (assessment tool developed in our center), Mayo wrist score and DASH scores. However 2 patients developed delayed extensor pollicis longus tendon rupture more than 3 months after the surgery, possibly from attrition from bone graft or fragment edges. All three radiological parameters were corrected to within normal accepted range and post-operative computed tomography scans correlated well with the pre-operative scans.
