Background Coronoid fracture of ulna reflects the severity of the elbow trauma.It is mainly due to the fall with the elbow in a straight position,which caused by collision with trochlea of humerus,leading to elbow instability.Violent trauma often causes elbow dislocation.If the fracture block is large,because of the pulling force of tendon,it is not easy to maintain reduction,and the stability of the elbow is badly affected,often requiring surgery treatment to restore the stability of the joints.In our hospital,From November 2009 to January 2012,we treated 16 cases with fracture of coronary fracture with elbow arthroscopy assisting reduction and fixation.Methods From November 2009 to January 2012,we treated 16 cases with fracture of coronary fracture with elbow arthroscopy assisting reduction and fixation,including 10 males and 6 females,with an average age of 39(24-51).There are 11 cases caused by fall and 5 cases caused by traffic accidents ; 6 cases were the left side,and 10 cases were on the right side;There were one case combined with fracture of the humeral capitellum and 3 cases combined with posterolateral rotation instability;According to Regan-Morrey classification:Ⅱ type 10 cases,Ⅲ type 6 cases.Diagnosis by preoperative elbow CT and three-dimensional imaging,we accurately knew of fracture position,size of fracture block,the degree of displacement of fracture.With general anesthesia and lateral position,the patients were positioned with limb in the elbow ancon.To applly pneumatic tourniquet inflation pressure band,with the pressure of 240 mmHg,tourniquet time 40-90 min,average(63.3±25.0) min.Anterolateral approach in the elbow-flexion position and proximal medial approach from the proximal part were used,because:(1) there is safest distance of ulnar nerve and median nerve in anterolateral approach in the elbow-flexion position,it is the safest approach in the medial approach into the road (the distance to the ulnar nerve is 15.5 mm,the distance to the median nerve is 13.8 mm).(2) there is safest distance(10 mm) to radial nerve in the anterolateral approach to,With the advantage of flexible operation and good microscopic field of vision,it is the most safe and effective one of the lateral approachs into the way;(3) We choose the position of 90° elbow flexion position to puncture operation since nerve is away from point of puncture.Usually water injection were operated from the lateral approach establishing arthroscopy channel,cleaning blood stasis and synovial joints of joint,exposing fracture block of coronary,and completing the reduction with arthroscopy.After the satisfied reduction,to fix the fracture from the back to coronary direction with screws or wires.Usually,the appropriate length of hollow screw is 3.0 mm,and the cutting-edge through coronary is not more than 2 mm.Also,the needle tail should be placed subcutaneously after bending.To combined fractures,such as capitellum fractures,open reduction and fixation is needed at the same time,including the repair or reconstruction of the lateral collateral ligament when posterolateral rotation unstability occurrs.Elbow should be fixed in a flexion position no less than 1 week,then early functional exercise was operated under the guidance of doctor.Results 14 cases were followed-up,with an average time of 12.6 months (8-24 months).All the postoperative incision healed good(type Ⅰhealing),no incisional drainage,nerve damage and fracture displacement occurs,with 1 case of heterotopic ossification.X ray film was applied at the time of terminal follow-up to assess fracture healing,showing fracture clinical healing of all the cases,and the healing time was 10-14 weeks,12 weeks on average.All patients reached anatomical reduction in the operation.The improved elbow HSS score was an average of 33 (28-35),average score of Visual Analog Scale is 1.2±0.5,with an average of 132.4° of elbow flexion,and 10.6° of elbow straighten,68.5° of pronation,78.6° of supination.the total good and excellent rate was 100%(14/14).Discussion Discuss Elbow joint is is composed of trochlea of humerus and half-month notch of ulna,composed of coronary and olecranon.Ulna coronary is the most important humeral blocking structure in front of elbow,which is an important part preventing elbow dislocation and posteriormedial rotation unstability.There are many important soft tissue attachment points important structures in front of the elbow including the joint capsule,the medial collateral ligament,brachialis,and so on,.It is the main stable structure of elbow,resisting biceps,brachialis and triceps pulling ulna to elbow.Coronary processes is an important part of the anterior column and the medial column,forming a stable ring in front of the elbow.When it damages,elbow medial and front instability may occurs.Improper handling may lead to habitual dislocation.Therefore,in the treatment of ulna coronary fracture,restore or rebuild the height and shape of the coronary and repair or reconstruction the anterior beam of medial collateral ligament is very important.With development of further research of elbow joint,the important role of elbow has been recognized,the fractures usually lead to complex traumatic elbow instability,so the treatment of ulna coronary fracture also attract more and more attention of surgons.When the fracture fragment is large(Regan-Morrey Ⅱ,Ⅲ),because of the flexor pull leading fracture displacement,elbow instability easily occurs and it is difficult.to manually reduce and maintain the position of fracture.And because the fracture is hard to expose,and fix,especially for small pieces or comminuted fracture of the coronary.Improper treatment may easily causes joint instability,myositis ossificans,traumatic arthritis,stiff joints,etc.Coronary fracture belongs to intra-articular fracture,anatomical reduction and strong internal fixation is the basis of the joint function recovery in the treatment of intra-articular fractures.Anatomical reduction is beneficial to the activities of the joint,relieve joint pain,and prevent the occurrence of traumatic arthritis;Strong internal fixation is beneficial to early functional exercise and prevent the stiffness of the elbow joint,reduce muscle atrophy,and dynamic instability and prevent the occurrence of traumatic arthritis,achieving good function.Ulna coronary fractures often combined with elbow instability,foreign scholars not only reported and discussed the treatment and prognosis,but also put forward the diagnostic criteria and surgical treatment scheme.Domestic scholars have similar report and literature review,introduces the treatment experience,and discuss new approaches and solutions,etc.The main method of fixation are steel wire fixation,kirschnerwire fixation,mini screw internal fixation,mini plate internal fixation and absorbable screw fixation,etc.Open reduction and internal fixation of coronary fracture was operated through the conventional anterior approach,but it is very difficult to coronary reduction and internal fixation,because:(1) the neurovascular structure in front of the elbow closely packed,operation through blood vessels or nerve gap is safe,and the vice injury occures easily; (2) the position of coronary is deep,it is very difficulty to touch the fracture line,because there is a lot of soft tissue,in this case it is difficult to touch the front clear fracture line and clean.If the soft tissue on the coronary was cleaned radically,including the attachment point of the medial collateral ligament,the brachial muscle,and the joint capsule,the meaning of reduction will lose;(3) fragment of coronal fractures tend to be small,the compaction fingers from the anterior part may occupy the fixing position again;(4)surgery of open reduction is a kind of great trauma,easily lead to heterotopic ossification and larger scars left,affecting beautiful appearance.With the deep understanding of the anatomy of elbow function and the improvement of elbow function requirements of patients,and minimally invasive surgery is more and more become a safe and effective treatment of intra-articular fractures.Because arthroscopy surgery has the advantages of little trauma and quick recovery in recent years,the application in the elbow fracture has made rapid progress.In acute elbow trauma,elbow arthroscopy technology can not only clean up small pieces fragment including cartilage ones,but also compete reduction and internal fixation of fracture feasiblly.And radial head fractures,olecranon fractures,coronoid process fractures,humerus condyle fracture reduction and internal fixation were reported.Adams reported 7 cases of ulna coronary condyle fracture appling elbow arthroscopy technology for reduction and fixation,final follow-up showed the curative effect is satisfied,with no heterotopic ossification and elbow arthritis.Operation approach of elbow arthroscopy are anterolateral approach and anteromedial approach in the position of elbow flexion.Because:(1) there is safest distance of ulnar nerve and median nerve in anterolateral approach in the elbow-flexion position,it is the safest approach in the medial approach into the road (the distance to the ulnar nerve is 15.5 mm,the distance to the median nerve is 13.8 mm).(2) there is safest distance(10 mm) to radial nerve in the anterolateral approach to,With the advantage of flexible operation and good microscopic field of vision,it is the most safe and effective one of the lateral approachs into the way;(3) We choose the position of 90° elbow flexion position to puncture operation since nerve is away from point of puncture.For Regan-Morrey Ⅱ type comminuted fracture,preoperative CT fully estimated size of fracture block,due to the small fracture fragment,cannulated screws may break down the fracture fragment and the fixing effect is not exact.To prevent this occurs,for Regan-Morrey Ⅱ type frature.we fix with kirschner wire from the back of the elbow to coronary direction ;For Regan-Morrey Ⅱ type simple fracture and Regan-Morrey Ⅲ type fracture,if the fragment is large,hollow screws should be used from the back of the ulna to the coronary direction.Compared with other joints,arthroscopy technical of elbow joint requires higher technique. performer must be very familiar with anatomy around the elbow.Because the structure is complex around the elbow joint with a lot of important nerve and blood vessels,although elbow surgery is a kind of effective and minimally invasive treatment,the incidence of complications than knee and shoulder arthroscopy surgery is higher,but the majority are mild reversible disease,and after some measures,these complications can be avoided,so the elbow arthroscopy surgery is a safe and effective technique.In addition,arthroscopic technique can provide better joint vision,less surgical trauma,less postoperative recovery time.Application of elbow arthroscopic technique assisted reduction and fixation in the treatment of ulna coronary fracture has the advantage of small incision,small trauma,good effect,fast recovery,etc.articular surface can be observed directly under arthroscopy,leading anatomicalintra-articular reduction,reducing traumatic arthritis,and can make the complications such as nerve,blood vessel damage to a minimum extent,still can reduce surgical trauma and reduce the complications of elbow injury.But the performer should has rich experience in the microscopic operation and local anatomical knowledge,strictly control the choice of operation indication,in order to avoid the happening of the complications to the maximum extent.