BACKGROUND:Proximal humerus internal locking system locking plate is the most commonly used fixation method for proximal humeral fractures,but its failure rate is still high in clinical practice.Reasonable screw placement is an important factor affecting the stability of internal fixation. OBJECTIVE:To investigate the distribution of humeral head screws in the treatment of proximal humeral fractures with proximal humerus internal locking system plate and its influence on internal fixation failure. METHODS:From January 2017 to December 2021,data from patients with proximal humeral fractures undergoing proximal humerus internal locking system plate in Third Affiliated Hospital of Guangzhou University of Chinese Medicine were retrospectively analyzed.A total of 124 patients were enrolled,including 16 males and 108 females,at the age of≥60 years.According to whether there was internal fixation failure after operation,they were divided into normal group(n=101)and internal fixation failure group(n=23).The patient's age,gender,fracture type,the integrity of the medial column,plate height,neck-shaft angle,whether the talus screw was inserted,and the number of humeral head screws,were collected.The humeral head was divided into eight zones according to the postoperative digital radiography anteroposterior film,and the distribution characteristics of the screws in each zone were collected,and the heat map of the screw distribution was drawn. RESULTS AND CONCLUSION:(1)There were no significant differences between the two groups in age,gender,fracture type,the integrity of the medial column,plate height,neck-shaft angle,whether to insert talus screws,and the number of humeral head screws(P>0.05).(2)The heat map showed that the humeral head screws were evenly distributed in the normal group,mainly scattered in zones 4,6,and 7.However,the screw distribution in the internal fixation failure group was not uniform,mainly concentrated in zones 4 and 6.In addition,in the ideal area of talus screws(7/8 zone),there were significantly more screws in the normal group than in the internal fixation failure group.(3)It is indicated that in the treatment of proximal humeral fractures with proximal humerus internal locking system plate,the uniform distribution of humeral head screws is the key to ensuring the internal fixation effect.A reasonable distribution of humeral head screws helps to improve the treatment effect and the success rate of internal fixation.

BACKGROUND:Palmar locking plate fixation is the most commonly used fixation method for distal radius fractures.However,when the fracture line involves the dorsal articular surface,palmar plate fixation carries a higher risk of postoperative displacement of the dorsal bone mass,especially the dorsal sigmoid notch bone mass. OBJECTIVE:To analyze the fracture line characteristics of distal radius fracture involving the dorsal articular surface,and further investigate the risk factors of postoperative displacement of the dorsal bone mass involving the sigmoid notch,so as to provide evidence for improving the success rate of surgery. METHODS:Retrospective analysis was performed on patients with distal radius fracture who were admitted to Third Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2021 to September 2022.The number of dorsal fractures of the distal radius of 1,2,3 and above was divided into types Ⅰ,Ⅱ,and Ⅲ based on preoperative CT images.The fracture line maps were drawn respectively to analyze the morphological characteristics of the dorsal fracture lines.Patients with dorsal sigmoid notch fracture were followed up for more than 3 months and divided into displaced group and non-displaced group according to whether the dorsal sigmoid notch bone mass displacement occurred after surgery.Age,sex,preoperative and postoperative CT anatomical parameters were compared between the two groups. RESULTS AND CONCLUSION:(1)145 patients with type C of AO/OTA involving the dorsal articular surface were analyzed by fracture line map.According to the number of dorsal fractures,there were 25 cases of type Ⅰ fracture(17.2％),82 cases of type Ⅱ fracture(56.6％),and 38 cases of type Ⅲ fracture(26.2％).Fracture line map showed that the fracture line of type Ⅰ fracture block mainly involved sigmoid notch;type Ⅱ mainly involved sigmoid notch and lister tubercle,and type Ⅲ involved sigmoid notch,lister tubercle,and dorsal radial column.Among the 145 patients,86.2％(125/145 cases)were involved in sigmoid notch,of which type Ⅲ was involved as high as 94.7％(36/38 cases);type Ⅱ was involved as high as 88.0％(72/82 cases),and type Ⅰ was involved as high as 68％(17/25 cases).(2)76 cases of type C of AO/OTA involving the dorsal sigmoid notch were included for further study,of which 65 cases were not displaced after operation and 11 cases were displaced.In univariate analysis,there were no statistically significant differences between the two groups in age,sex,injury site,preoperative CT dorsal sigmoid notch bone mass length(d1),ulnar length(d2),dorsal height of dorsal sigmoid notch bone mass(d4),and ulnar edge distance between steel plate and radius(d5)(P>0.05).The proportion of dorsal sigmoid notch involving the radioulnar joint:[d2/(d2+d3)],the proportion of articular surface of dorsal sigmoid notch(s1/s2),the distance between the ulnar screw tail and the edge of dorsal sigmoid notch(d6),and the number of screw fixation of dorsal sigmoid notch were statistically significant(P<0.05).(3)Multivariate Logistic regression analysis showed that the number of screw fixation of sigmoid notch was the only risk factor affecting the displacement of sigmoid notch on dorsal ulnar side(P<0.05).(4)It is indicated that type Ⅱ is the most common intra-articular fracture of distal radius involving the back of the radius,followed by type Ⅲ and type Ⅰ with dorsal sigmoid notch bone mass.However,the dorsal sigmoid notch bone mass is prone to postoperative displacement due to the influence of the inferior radioulnar joint ligament,and the fixation of at least one effective screw during the operation can reduce the risk of displacement and help to improve the treatment effect.