Anatomical Study For The Treatment Of Proximal Humeral Fracture Through The Medial Approach

Background:Although open reduction internal fixation(ORIF)is still the mainstream treatment for proximal humeral fractures,the treatment of complex 3-part and 4-part proximal humeral fractures has been controversial due to such as varus malunion,avascular necrosis of the humeral head and other postoperative complications.With the development of internal fixation techniques,strengthening the medial column in proximal humeral fractures has been widely recognized,and new techniques and concepts have emerged.The purpose of this study was to elucidate the medial approach to proximal humeral fractures through autopsy.Method:Upper limbs from 20 cadavers have been dissected to expose the shoulder joint through a medial approach.We selected the coracoid process as the bony reference.Vernier caliper will be used to measure the following data,including distance from coracoid process to anterior circumflex humeral artery(ACHA)and posterior circumflex humeral artery(PCHA),distance between anterior circumflex humeral artery(ACHA)and posterior circumflex humeral artery(PCHA)and their diameters.Assessment included the characteristics of the vascular supply around the humeral head,identification of the structures at risk,quality of exposure of the bony structures,and feasibility of fixation.Results:The medial approach is appropriate in 87.50%anatomical patterns.Between the lower part of the shoulder capsule and the insertion of conjoined tendon of the latissimus dorsi and teres major muscles,the bony surface exposed was limited by the interval between ACHA and PCHA.An interval of 2 to 3 cm(24.60 ± 3.24 mm)was available for medial plate.ACHA(49.33±7.92 mm,35.14-68.53 mm)and PCHA(49.78±7.64 mm,37.67-66.76 mm)were about 5 cm away from the coracoid process.Low-risk structures including ACHA and PCHA originate in common,musculocutaneous nerve intersects with ACHA,the diameter of PCHA:ACHA<1.5.High-risk structures including PCHA originated from the deep brachial artery(DBA),the presence of perforator vessels between ACHA and PCHA.In 12.50%anatomical patterns,this risk structure should be taken seriously.Conclusion:The medial approach provides a new perspective in the optimal management of complex fractures of proximal humerus.Anatomical research proves that the medial approach is feasible,but the protection of ACHA and some anatomical variations,such as the variation of PCHA and the crossing position of musculocutaneous nerves,require skilled surgical techniques of surgeons.To some extent,this study supports that the humeral head blood transport is more dependent on PCHA.This paper also provides some data support for the selection of medial humeral internal fixation and the preoperative localization of ACHA and PCHA by body surface markers.In this study,indications for medial approach were discussed for ACHA injuries and fracture types in proximal humeral fractures.With further studies on the anatomy and mechanism of injury,the development of more clinical cases and prognosis observation will be an important work of our institution in the future.