The Role Of High Frequency Ultrasonography In Diagnosis Of Acute Closed Injury Of Extensor Digital Tendon

Acute closed injury of extensor digital tendon is very common in clinic and often has definite etiology[1-2].The commonly used extensor tendon division in hand and foot surgery of Shandong Provincial Hospital is as follows:Zone Ⅰ:dorsal base of distal phalanx to central slip end;Zone Ⅱ:central slip end to the middle of point proximal phalanx;Zone Ⅲ:the middle of point proximal phalanx to the distal margin of extensor retinaculum;zone Ⅳ:deep surface of extensor retinaculum;zone Ⅴ:the proximal margin of the extensor retinaculum to the origin of extensor.For acute closed injury of extensor digital tendon in zone Ⅰ-Ⅴ hand surgeons used to make preliminary diagnosis of various types of injuries mainly according to different clinical signs and X-ray findings.However,X-ray can only indicate the existence of fractures,can not provide the information of extensor tendon.And we can not accurately estimate the location and extent of the extensor tendon injury only by clinical signs.And extensor tendon is relatively thin.Compared with flexor tendon,it is difficult to observe extensor tendon by ultrasonography in the past.So there is no objective and direct imaging evaluation method for acute closed injury of extensor digital tendon.With the development of ultrasonography technology,especially the application of high-frequency probe,the resolution of ultrasonography is getting higher and higher,the display of extensor tendon is becoming clearer and clearer[3],and even the display of avulsed bone fragment is also very clear and accurate.In addition,we can observe and estimate the sliding of extensor tendon in real time by active or passive finger movement with ultrasonography.High frequency ultrasonography has been widely used in the diagnosis of acute closed injury of extensor digital tendon[4].From September 2009 to January 2017,103 patients with acute closed extensor tendon injury diagnosed by hand surgeons in Shandong Provincial Hospital were examined by ultrasonography.The location and extent of extensor tendon injury were defined,the ultrasonographic features were described,and the ultrasonographic manifestations of extensor tendon injury were summarized.In addition,clinicians need the explicit types of extensor tendon injuries in order to make reasonable treatment plans,which is particularly important in the most common disease--acute closed injury of Zone I extensor digital tendon(acute closed mallet fingers).Therefore,based on the ultrasonographic findings of the patients with acute closed injury of zone I extensor digital tendon(acute closed mallet finger),a new kind of classification of acute mallet finger injury was proposed.Furthermore,compared with MRI and X-ray,the difference in terms of extensor tendon injury and bony fragment identification ability among the three types of examinations were described respectively.Through this study,we hope to provide more accurate and effective imaging information for hand surgeons,achieving accurate clinical diagnosis of acute closed injury of extensor digital tendon,and to guide clinical treatment so as to facilitate the recovery of the affected limb function as soon as possible.Part IThe role of high frequency ultrasonography in diagnosis of acute closed injury of zone I extensor digital tendon(acute closed mallet finger injury)Thirty-six patients each with an acute closed mallet finger injury referred to the orthopaedic department of our hospital from Sep 2009 to Jan 2017 were included into this study.All presented with a flexion deformity of a single finger at the distal interphalangeal joint(DIP).Duration of symptoms reported by the patients varied from 1 day to 2 weeks.All patients underwent ultrasonography,magnetic resonance imaging(MRI)and X-ray examinations.A new kind of classification of acute mallet finger injury based on ultrasonography findings was described.The difference in terms of extensor tendon injury and bony fragment identification ability among the three types of examinations were described respectively.The following results were obtained:(1)Types of acute closed mallet finger based on ultrasonography findings.1)Type A,avulsion fracture without extensor tendon rupture.The ultrasonography showed hyperechoic fracture fragments of the distal phalangeal base and the thicker extensor tendon due to shortening,with the hyperechoic fracture fragments at the distal margin;no real-time gliding of the extensor tendon was found during either active or passive movements of the DIP.2)Type B,complete tendon rupture without fracture.Longitudinal evaluation showed,in Fig 3,the disruption of the extensor tendon at the level of DIPs with retraction of the proximal tendon stump but no fracture fragments of the distal phalangeal base;no real-time gliding of the extensor tendon during either active or passive movements of the DIP was found.3)Type C,contusion of extensor tendons.The ultrasonography showed the thicker and hypoechoic extensor tendon which was still integrate in longitudinal plane(Fig 4).Real-time gliding of the extensor tendon during both active and passive movements of the DIP could be found.(2)The difference in terms of extensor tendon injury and bony fragment identification ability among the three types of examinations.Compared with X-ray,ultrasonography and MRI could show the extensor tendon injury clearly.While compared with MRI,ultrasonography and X-ray was more sensitive in showing bony fragment.Either an injury of extensor digital tendon or an avulsion fracture of distal phalangeal base was identified clearly on ultrasonography.And the real-time observation of ultrasound can estimate the function of extensor tendon.Therefore,high frequency ultrasonography could be an important method in diagnosis of acute close mallet finger injury.Part IIThe role of high frequency ultrasonography in diagnosis of acute closed injury of zone II-V extensor digital tendonAlthough acute closed injury of zone I extensor digital tendon(acute closed mallet finger)is the most commonly affected as its superficial location[5],lacking blood supply[6],and Uechanical factors[7],acute closed injury of zone Ⅱ-Ⅴ extensor digital tendon are not rare in clinical hand surgery.From Sep 2009 to Jan 2017,67 patients each with an acute closed injury of zone Ⅱ-Ⅴ extensor digital tendon referred to the orthopaedic department of our hospital were included into this study.High frequency ultrasonography was performed on all patients,and their sonographic features were summarized and analyzed.The following results were obtained:(1)20 cases of extensor tendon central slip injury or rupture,presenting with a flexion deformity of a single finger at the proximal interphalangeal joint(PIP),hyperextension of distal interphalangeal joint.The ultrasonographic features of the extensor tendon central slip rupture were:the interruption of the central slip at the base of the phalanx,contracture of the extensor tendon stumps,and local non-echo area.No real-time gliding of the extensor tendon during either active or passive movements of the PIP was found.The ultrasonographic features of the extensor tendon central slip injury were:tendon thickening and heterogeneous echo.Real-time gliding of the extensor tendon during both active and passive movements of the PIP could be found but the slip amplitude is reduced.(2)9 cases of extensor tendon hood injury,presenting with a extensor tendon lateral displacement deformity of a single finger.The ultrasonographic features of extensor tendon hood rupture were:the interruption of extensor tendon hood,unclear structure,and local non-echo area.Dynamic observation showed that the ruptured end was separated and the extensor tendon slided to the healthy side.(3)29 cases of spontaneous tendon rupture at the level of dorsal wrist,presenting with a extension disorder of the finger.The ultrasonographic features were:the interruption of tendon,contracture of the extensor tendon stumps,and local non-echo or flocculent hypoechoic area between the extensor tendon stumps.No real-time gliding of the extensor tendon during either active or passive movements was found.(4)9 cases of extensor injury,presenting with a extension disorder of the finger after forearm trauma.The ultrasonographic features were:the volume of the forearm extensor muscle bundle was enlarged,the structure was not clearly displayed of extensor muscle fiber,the continuity of local muscle fiber was interrupted.non-echo area was detected and blood flow signal increased inside the muscle bundle.This part shows that high frequency ultrasonography can clearly show the location and degree of acute closed extensor tendon injury in zone Ⅱ-Ⅴ,accurately locates the extensor tendon stump and the distance between the extensor tendon stumps,whether there is contracture or effusion,providing imaging evidence for the next step of clinical treatment.And the real-time observation of ultrasound can estimate the function of extensor tendon.Therefore,high frequency ultrasonography could be an important method in diagnosis of acute closed injury of zone Ⅱ-Ⅴ extensor digital tendon.To sum up,high frequency ultrasonography can evaluate acute closed extensor tendon injury accurately,and provide effective imaging information for clinical treatment,so as to guide the selection of clinical treatment and operation,so as to facilitate the recovery of the affected limb function as soon as possible.In short,high frequency ultrasonography could be an accurate and reliable imaging method in diagnosis of acute close mallet finger injury,and provide imaging evidence for clinical diagnosis and treatment,which is of great significance.