[Influence of anterior fracture line on anterior cortical reduction loss after cephalomedullary nail fixation in intertrochanteric fractures]

Objective

To investigate the position of the anterior fracture line in AO/Orthopaedic Trauma Association (AO/OTA) type A2 unstable intertrochanteric fractures and its impact on the incidence of anterior cortical reduction loss after cephalomedullary nail fixation.

Methods

A clinical data of 95 patients with intertrochanteric fractures who met the selection criteria between April 2020 and February 2023 was retrospectively analyzed. All patients were treated with cephalomedullary nail fixation, and the intra- and post-operative imaging data were complete. Among them, there were 37 males and 58 females. The age ranged from 61 to 97 years, with an average of 79.6 years. The time from injury to operation ranged from 7 hours to 11 days, with an average of 2.8 days. According to the 2018-AO/OTA classification standard, there were 39 cases of type 31-A2.2 and 56 cases of type 31-A2.3. Intraoperative fluoroscopy was used to record the number of patients with satisfactory fracture alignment. The preoperative CT data were imported into Mimics17.0 software to simulate the fracture reduction and measure the distance between the anterior fracture line and the intertrochanteric line bony ridge. The fractures were classified as transcapsular fractures, extra-capsular fractures, and intra-capsular fractures according to the distance. CT three-dimensional reconstruction was performed within 2 weeks after operation to observe the number of patients with anterior cortical reduction loss. The postoperative anterior cortical reduction loss incidence in patients with satisfactory fracture alignment, and the relationship between postoperative anterior cortical reduction loss and the position of the anterior fracture line were observed.

Results

There were 52 cases (54.7%) of transcapsular fractures, 24 cases (25.3%) of extra-capsular fractures, and 19 cases (20.0%) of intra-capsular fractures. Among them, 41 of the 52 transcapsular fractures had satisfactory fracture alignment, and 4 (9.8%) of them experienced anterior cortical reduction loss after operation; 19 of the 24 extra-capsular fractures had satisfactory fracture alignment, and no anterior cortical reduction loss occurred; 16 of the 19 intra-capsular fractures had satisfactory fracture alignment, and 7 (43.8%) of them experienced anterior cortical reduction loss after operation. There was a significant difference in the incidence of anterior cortical reduction loss between groups ( χ 2=8.538， P=0.003). All patients were followed up 3-26 months (mean, 9 months). Among them, 91 cases had fracture healing, and 4 cases had nonunion.

Conclusion

In AO/OTA type A2 unstable intertrochanteric fractures, where the anterior fracture line is located within the joint capsule, there is a high risk of anterior cortical reduction loss after operation.

[Off target of distal interlocking screw in short cephalomedullary nail fixation for intertrochanteric femur fractures]

Objective

To analyze the causes and treatment of off target of the distal interlocking screws when short cephalomeduallry nails were installed through jig-guided targeting device, and to put forward the technical points to prevent off target.

Methods

Retrospective analysis of 9 patients with intertrochanteric fractures treated between July 2014 and June 2023 was conducted, in which off target occurred during the insertion of the distal interlocking screw by jig-guided targeting device in short cephalomedullary nailling (<24 cm). There were 1 male and 8 females, with an average age of 82.7 years (range, 73-94 years). There were 3 cases of type A1, 5 cases of type A2, and 1 case of type A3 according to 2018-AO/Orthopaedic Trauma Association (AO/OTA) fracture classification. As for the misaligned distal interlocking screw, six parameters were collected and analyzed, including the time of finding, the position, the type of passing through the cortical bone, the special circumstances during operation (such as the need to remove the intramedullary nail for reaming the diaphysis, hammering, etc.), the treatment, and the patient follow-up results.

Results

In the 9 patients, the off target of the distal interlocking screw was found in 7 cases during operation and in 2 cases after operation; the locking screw was located behind the nail in 7 cases and in front of the nail in 2 cases; the off target locking screw was passing tangentially in transcortical patern in 6 cases and in bicortical pattern through the medullary cavity in 3 cases. Three cases were attributed to the mismatch between the nail and the femur, two of which were attributed to the narrow femoral medullary cavity, one of which was attributed to the large anterolateral femoral bowing, and the other 6 cases were attributed to technical errors such as the loosening of the jig-guided targeting device, the tension of the fascia lata, and the blunt of the drill. In the 7 cases found during operation, the misaligned interlocking screw was removed first and the screw hole was left vacant, then in 2 cases, the interlocking screw was not used further; in 1 case, the distal dynamic hole was successfully inserted with a dynamic guide frame, and in 4 cases, the interlocking screw was successfully put after 2-3 attempts, leaving a large hole in the lateral cortex. No special treatment was performed in 2 cases found after operation. One patient was out of bed early after operation, 7 patients were in bed for 1 month, and 1 patient deteriorated to A3 type after operation and was in bed for 3 months. All the 9 patients were followed up 6-12 months, with an average of 8 months. Fracture healing was achieved in 8 patients. One patient with vacant interlocking screw had a secondary spiral fracture of the femoral shaft 3 months later, and was refixed with a long cephalomedullary nail and circlage wiring.

Conclusion

Distal interlocking screw off target is rare, but when it occurs, it leaves a large cortical hole in the osteoporotic femoral shaft, reducing bone strength; the use of precision instruments and attention to technical details can reduce this adverse phenomenon.

[Research progress on valgus impacted proximal humeral fractures]

Objective

To review the advancement made in the understanding of valgus impacted proximal humeral fracture (PHF).

Methods

The domestic and foreign literature about the valgus impacted PHF was extensively reviewed and the definition, classification, pathological features, and treatment of valgus impacted PHFs were summarized.

Results

PHF with a neck shaft angle ≥160° is recognized as a valgus impacted PHF characterized by the preservation of the medial epiphyseal region of the humeral head, which contributes to maintenance of the medial periosteum's integrity after fracture and reduces the occurrence of avascular necrosis. Therefore, the valgus impacted PHF has a better prognosis when compared to other complex PHFs. The Neer classification designates it as a three- or four-part fracture, while the AO/Association for the Study of Internal Fixation (AO/ASIF) categorizes it as type C (C1.1). In the management of the valgus impacted PHF, the selection between conservative and surgical approaches is contingent upon the patient's age and the extent of fracture displacement. While conservative treatment offers the advantage of being non-invasive, it is accompanied by limitations such as the inability to achieve anatomical reduction and the potential for multiple complications. Surgical treatment includes open reduction combined with steel wire or locking plate and/or non-absorbable suture, transosseous suture technology, and shoulder replacement. Surgeons must adopt personalized treatment strategies for each patient with a valgus impacted PHF. Minimally invasive surgery helps to preserve blood supply to the humeral head, mitigate the likelihood of avascular necrosis, and reduce postoperative complications of bone and soft tissue. For elderly patients with severe comminuted and displaced fractures, osteoporosis, and unsuitable internal fixation, shoulder joint replacement is the best treatment option.

Conclusion

Currently, there has been some advancement in the classification, vascular supply, and management of valgus impacted PHF. Nevertheless, further research is imperative to assess the clinical safety, biomechanical stability, and indication of minimally invasive technology.

[Three-dimensional finite element analysis of exo-cortical placement of humeral calcar screw for reconstruction of medial column stability]

Objective

To explore the biomechanical stability of the medial column reconstructed with the exo-cortical placement of humeral calcar screw by three-dimensional finite element analysis.

Methods

A 70-year-old female volunteer was selected for CT scan of the proximal humerus, and a wedge osteotomy was performed 5 mm medially inferior to the humeral head to form a three-dimensional finite element model of a 5 mm defect in the medial cortex. Then, the proximal humeral locking plate (PHILOS) was placed. According to distribution of 2 calcar screws, the study were divided into 3 groups: group A, in which 2 calcar screws were inserted into the lower quadrant of the humeral head in the normal direction for supporting the humeral head; group B, in which 1 calcar screw was inserted outside the cortex below the humeral head, and the other was inserted into the humeral head in the normal direction; group C, in which 2 calcar screws were inserted outside the cortex below the humeral head. The models were loaded with axial, shear, and rotational loadings, and the biomechanical stability of the 3 groups was compared by evaluating the peak von mises stress (PVMS) of the proximal humerus and the internal fixator, proximal humeral displacement, neck-shaft angle changes, and the rotational stability of the proximal humerus. Seven cases of proximal humeral fractures with comminuted medial cortex were retrospectively analyzed between January 2017 and December 2020. Locking proximal humeral plate surgery was performed, and one (5 cases) or two (2 cases) calcar screws were inserted into the inferior cortex of the humeral head during the operation, and the effectiveness was observed.

Results

Under axial and shear force, the PVMS of the proximal humerus in group B and group C was greater than that in group A, the PVMS of the internal fixator in group B and group C was less than that in group A, while the PVMS of the proximal humerus and internal fixator between group B and group C were similar. The displacement of the proximal humerus and the neck-shaft angle change among the 3 groups were similar under axial and shear force, respectively. Under the rotational torque, compared with group A, the rotation angle of humerus in group B and group C increased slightly, and the rotation stability decreased slightly. All the 7 patients were followed up 6-12 months. All the fractures healed, and the healing time was 8-14 weeks, with an average of 10.9 weeks; the neck-shaft angle changes (the difference between the last follow-up and the immediate postoperative neck-shaft angle) was (1.30±0.42)°, and the Constant score of shoulder joint function was 87.4±4.2; there was no complication such as humeral head varus collapse and screw penetrating the articular surface.

Conclusion

For proximal humeral fractures with comminuted medial cortex, exo-cortical placement of 1 or 2 humeral calcar screw of the locking plate outside the inferior cortex of the humeral head can also effectively reconstruct medial column stability, providing an alternative approach for clinical practice.