Biomechanical comparison of screw-based zones of a spatial subchondral support plate for proximal humerus fractures

Stabilisation of proximal humerus fractures remains a surgical challenge. Spatial subchondral support (S3) plate promises to overcome common complications associated with conventional proximal humerus plates. This study compared the biomechanical performance of S3 plate with a fixed-angle hybrid blade (Equinoxe Fx) plate and a conventional fixed-angle locking plate (PHILOS). The effects of removal of different S3 plate screws on the humeral stability were also investigated. A total of 20 synthetic left humeri were osteotomised transversely at the surgical neck to simulate a two-part fracture and were each treated with an S3 plate. Head screws were divided into three zones based on their distance from the fracture site. Specimens were divided into four equal groups where one group acted as a control with all screws and three groups had one of the screw zones missing. With humeral head fixed, humeral shaft was first displaced 5 mm in extension, flexion, valgus and varus direction (elastic testing) and then until 30 mm varus displacement (plastic testing). Load–displacement data were recorded to determine construct stiffness in elastic tests and assess specimens’ varus stability under plastic testing. Removal of the screw nearest to the fracture site led to a 20.71% drop in mean elastic varus bending stiffness. Removal of the two inferomedial screw above it resulted in a larger drop. The proximal screw pair had the largest contribution to extension and flexion bending stiffness. Varus stiffness of S3 plate constructs was higher than PHILOS and Fx plate constructs. Stability of humeri treated with S3 plate depends on screws’ number, orientation and location. Varus stiffness of S3 plate construct (10.54 N/mm) was higher than that of PHILOS (6.61 N/mm) and Fx (7.59 N/mm) plate constructs. We attribute this to S3 plates’ thicker cross section, the 135° inclination of its screws with respect to the humeral shaft and the availability of pegs for subchondral support.

Download Full-text

Biomechanical comparison of a unique locking plate versus a standard plate for internal fixation of proximal humerus fractures in a cadaveric model

Clinical Biomechanics ◽

10.1016/j.clinbiomech.2006.06.005 ◽

2006 ◽

Vol 21 (10) ◽

pp. 1027-1031 ◽

Cited By ~ 75

Author(s):

Stephen Walsh ◽

Rudy Reindl ◽

Edward Harvey ◽

Gregory Berry ◽

Lorne Beckman ◽

...

Keyword(s):

Internal Fixation ◽

Locking Plate ◽

Proximal Humerus ◽

Plate Versus ◽

Proximal Humerus Fractures ◽

Standard Plate ◽

Humerus Fractures ◽

Biomechanical Comparison ◽

Cadaveric Model

Download Full-text

Initial varus displacement of proximal humerus fractures results in similar function but higher complication rates

Injury ◽

10.1016/j.injury.2016.01.021 ◽

2016 ◽

Vol 47 (4) ◽

pp. 909-913 ◽

Cited By ~ 18

Author(s):

Christina E. Capriccioso ◽

Joseph D. Zuckerman ◽

Kenneth A. Egol

Keyword(s):

Proximal Humerus ◽

Complication Rates ◽

Proximal Humerus Fractures ◽

Similar Function ◽

Varus Displacement ◽

Humerus Fractures

Download Full-text

Prospective observational study evaluating the outcome of a fixed angle plate (proximal humerus internal locking system) in proximal humerus fractures

International Journal of Research in Orthopaedics ◽

10.18203/issn.2455-4510.intjresorthop20195804 ◽

2019 ◽

Vol 6 (1) ◽

pp. 117

Author(s):

Kiran Ramachandran ◽

Jackson Mathew ◽

Praveen Koraboina ◽

Ponnezhathu Sebastian John

Keyword(s):

Functional Outcomes ◽

Proximal Humerus ◽

Osteoporotic Fractures ◽

Attrition Rate ◽

Proximal Humerus Fractures ◽

Fixed Angle ◽

Significant Difference ◽

Humerus Fractures ◽

Study Participants ◽

Type Of Fracture

Background: Proximal humerus fractures are common among elderly. The present study assesses the functional outcomes of fixed angle plate (proximal humerus internal locking system (PHILOS)) in fractures of proximal humerus.Methods: 30 participants aged ≥18 years with proximal humerus fracture (2, 3 and 4 part) who underwent PHILOS fixation were enrolled. Undisplaced, open, severely comminuted, metastatic, and pathological fractures and with associated head injury and neurovascular injuries wew excluded. Clinical and radiological evaluation were done pre and post-operatively. Intraarticular extent of fracture geometry was assessed using 3-dimensional computed tomography. Participants were managed preoperatively with analgesics and shoulder immobilizer followed by preanesthetic check-up and routine investigations and surgery was done once participants were stable. Sample size was calculated assuming excellent or satisfactory results in 80% participants 6 months after surgery, relative precision of 20%, α of 5% and 10% attrition rate. Institutional ethics committee approved the study and written informed consent was obtained from all study participants.Results: Mean age of study participants was 62.9 (14.9) years and were predominantly females (66.6%, n=20). No significant difference between type of fracture and duration of recovery was observed (p=0.4). 30% participants had post-operative complications, stiffness was the most common (13.3%, n=4) complication. 76.6% (n=23) participants had good functional outcomes. Significant correlation between type of fracture and NEER score was observed (p<0.0001).Conclusions: PHILOS is a preferential implant in proximal humerus fractures due to angular stability, particularly in comminuted fractures in younger patients, and osteoporotic fractures in elderly, thus allowing early mobilization and satisfactory final functional outcome.

Download Full-text