Biomechanical Analysis of Clavicle Hook Plates with a Range of Posterior Hook Offsets Implanted at Different Acromion Positions in the Acromioclavicular Joint: A Finite Element Analysis Study

The clavicle hook plate is commonly used in acromioclavicular injuries; however, the biomechanical effect of the posterior hook offset and hook position is unclear. This study applied a finite element analysis (FEA) to evaluate these parameters to improve the clinical strategy. Nine FEA models with 0-mm, 5-mm, and 10-mm posterior hook offsets implanted in the anterior, middle, and posterior acromion were established to evaluate the stress distribution and the reaction force on the acromion. The 5-mm and 10-mm posterior hook offsets at all acromion positions reduced the reaction force on the acromion but slightly increased the stress on the clavicle. The 0-mm offset increased the reaction force at all acromion positions and was relatively lower at the middle acromion. The clavicle hook plate with a posterior hook offset reduces the reaction force on the acromion, providing a flexibility of the hook position. These results provide surgeons with the biomechanical basis for the hook offset and position and engineers with the mechanical basis for the implant design.

Os acromiale may be a contraindication of the clavicle hook plate: case reports and literature review

Background Os acromiale can be potentially missed or misdiagnosed as acromion fracture, and this can affect treatment determination if it is complicated with an ipsilateral shoulder injury. The clavicle hook plate is a widely used technique for distal clavicle injuries, leading to transacromial erosion, particularly when in the presence of os acromiale. Case presentation A 70-year-old man and a 78-year-old man who had limited mobility and severe pain in their right shoulders following falls attended the emergency center. Both patients were diagnosed with os acromiale with CT or MRI and acute distal clavicle fracture or acromioclavicular joint dislocation. Following a comprehensive evaluation, os acromiale may limit the application of a clavicle hook plate due to potential transacromial erosion. The distal clavicle fracture with ipsilateral os acromiale received treatment with a volar radius locking T plate, and the acromioclavicular joint dislocation with ipsilateral os acromiale was reconstructed using suture anchors. Both yielded satisfactory outcomes and voided transacromial erosion. Conclusions Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate. An axillary lateral radiograph is recommended to detect potential os acromiale in patients using a hook plate.

Reduction of subacromial osteolysis by bending the hook arthroscopically in clavicle hook plate fixation for distal clavicle fractures

Background: Subacromial osteolysis is a serious complication caused by clavicle hook plates. Incongruency between the hook and undersurface of the acromion has been reported as a cause of subacromial osteolysis. The aim of this study was to retrospectively examine the effectiveness of hook bending in reducing subacromial osteolysis. Methods: Twenty-two patients with unstable distal clavicle fractures were treated with clavicle hook plates. There were 19 males and 3 females, with a mean age of 55.0 years. They were followed for a mean period of 9.5 months. The patients were divided into two groups; there were 10 patients whose hook was bent (the bending group) and 12 patients whose hook was not bent (the nonbending group). In the bending group, the hook was bent using a dedicated bender such that the hook and the undersurface of the acromion were parallel, and the direction of the hook was confirmed arthroscopically. At plate removal, arthroscopy was performed in both groups to observe the subacromial bony defect and the rotator cuff injury. Results: One patient in the nonbending group had a fibrous union, but bone union was achieved in all other patients. In the bending group, the angle at which the hook was inclined downward with respect to the distal portion of the plate (hook inclination angle) was 9.3 ± 6.1˚ (range, 2-23˚). The subacromial bony defects were significantly smaller in the bending group (1.7 ± 2.4 mm) than in the nonbending group (4.7 ± 2.3 mm) (P<0.05). Partial-thickness rotator cuff tears localized around the hook were observed arthroscopically in 6 patients in the bending group (60%) and in 7 patients in the nonbending group (58%). Conclusions: When the hook was bent such that it was parallel to the undersurface of the acromion, the degree of subacromial osteolysis was reduced.

Clavicle hook plate versus distal clavicle locking plate for Neer type II distal clavicle fractures

Background The purpose of this meta-analysis was to compare clavicle hook plates versus distal clavicle locking plates for the treatment of Neer type II distal clavicle fractures. Methods PubMed (1996 to January 2019), Embase (1980 to January 2019), Web of Science (1990 to January 2019), the Cochrane Library (January 2019), and the China National Knowledge Infrastructure (January 2019) were systematically searched without language restrictions for literature retrieval. The Constant-Murley shoulder joint function score at 3 and 6 months after the operation and the postoperative complications after the operation (shoulder joint pain, abduction restriction, fracture delay healing, subacromial impingement) were the outcomes. Stata 12.0 was used for the meta-analysis. Results A total of 9 clinical trials involving 446 patients were finally included in this meta-analysis. The results showed that the improvement in the Constant-Murley shoulder joint function score in the distal locking plate group was better than that in the clavicle hook plate group at 3 and 6 months after the operation (P < 0.05). There were fewer cases of shoulder joint pain and restricted shoulder abduction range of motion in the distal locking plate group, and the difference was statistically significant (P < 0.05). There were no statistically significant differences in fracture delay healing and subacromial impingement between the two groups (P > 0.05). Conclusion Compared with the clavicular hook plate, the distal clavicle locking plate for the treatment of Neer type II distal clavicle fractures is associated with better shoulder function recovery and fewer complications related to pain and abduction restriction.