Experimental Study and Preliminary Clinical Application of Miniinvasive Percutaneous Internal Screw Fixation for Scaphoid Fracture under the Guidance of a 3D-printed Guide Plate

This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The study consisted of two parts:(1)experimentation on upper limbs from corpses and(2)preliminary clinical application.Corpse experiments involved upper limbs of 6 adult corpses.The specimens of upper limbs were subjected to plain CT scan.Then the CT data were input into computer to conduct 3D reconstruction of wrist region.The direction and depth of the guide wire and screw were designed on the basis of the principle that screw should lie at the center of scaphoid and the long axis of the screw should be aligned with that of the scaphoid.The carpal bone model and the guide plate were designed and 3D-printed.By using the guide plates,the guide wire was placed and the cannulated compression screw was inserted.The wrist region was examined by X-ray and CT to observe the location of the screw in the scaphoid.The scaphoid was longitudinally excised to grossly observe the location and evaluate the result of screw insertion.For clinical application,the guide plate was employed in 4 patients with fresh scaphoid fracture using the aforementioned operative technique.Our results showed that,in the 6 corpse limbs,the guide plate well fitted the skin surface and the guide wire and screw were accurately put in place in one session.X-ray examination and gross observation confirmed that the screw was satisfactorily positioned and the result met the requirements of the preoperative design.For 4 patients,the guide wire and screw were all precisely inserted into place in one session.The operation time and X-ray exposure times were apparently reduced.The imaging examination exhibited satisfactory results and the hand functioned well.It was concluded that the operative guide plate used for the mini­invasive percutaneous internal screw fixation of fractured scaphoid not only can assist in accurate placement of screw but also shorten operation time and reduce insertion and X-ray exposure times,thereby reducing the radiation injury and damage to the substance and the blood circulation of carpal bone.Its use can also improve the learning curve of surgeons.

Nonunion of the scaphoid treated by anterior vascularized bone graft： a review of 26 cases

[Abstract] Objective： To evaluate the clinical and radiological outcome of anterior vascularized bone graft in the treatment of primitive nonunion of the scaphoid. Methods： This is a retrospective study of 26 scaphoid nonunion cases treated by this technique between 2004 and 2009. The mean age was 38 years. Nonunion was of types IIA and IIB according to the Alnot＇s classification and only one case showed a proximal pole necrosis （type IV）. The fixation was ensured by K-wire. The mean immobilization period was 9 weeks. Results： At mean 19 months follow-up, the bone union rate was 88.5%. Failure was noted in three cases. No significant complications secondary to this technique were observed. The mobility in extension and flexion had an average recovery of 18°. Nineteen patients （73%） were free of pain, and the others had occasional pain Conclusions： It is a meticulous surgical technique that provides better union rates than those of conventional scaphoid graft. This technique is first adopted in cases of failure of conventional grafts in the treatment of scaphoid nonunion but the encouraging results suggest expanding indications to primitive nonunion.

Anatomic measurement of wrist scaphoid and its clini-cal significance

Objective: To provide anatomical basis for the internal fixation of scaphoid fractures.Methods: The shape and vascular lake of 48 dry scaphoids and 36 wet scaphoids were observed.Results: The data of dry bone group and wet bone group were as follows: the height of scaphoid tubercle were (11.28±0.94) mm and (10.35±1.54) mm; the thickness of scapoid waist were (12.02±1.90) mm and (11.21±1.20) mm; the width of scapoid waist were (10.59±1.11) mm and (11.34±1.47) mm; the minimal thickness of the body of scapoid were (6.51±1.22) mm and (8.54±1.07) mm; the axis length of scapoid were (25.68±2.21) mm and (26.50±2.56) mm; the width of epicondyle of scaphoid of distal portion, waist and proximal portion were (6.50±1.06) mm, (5.14±1.01) nun, (4.42±1.16)mm and(6.64±1.18) mm, (6.01±0.75)mm and(5.71±0.78) mm, respestively. The main blood vessels came from the dorsal and the radial of wrist and passed through the whole scaphoid along the crest of scaphoid.Conclusion: The internal fixation of scaphoid can be designed according to the anatomical data without damag-ing the articular surface and blood supply.