[Operative treatment of proximal humeral fractures with helix wire]

Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures

Aims

Plating displaced proximal humeral fractures is associated with a high rate of screw perforation. Dynamization of the proximal screws might prevent these complications. The aim of this study was to develop and evaluate a new gliding screw concept for plating proximal humeral fractures biomechanically.

Methods

Eight pairs of three-part humeral fractures were randomly assigned for pairwise instrumentation using either a prototype gliding plate or a standard PHILOS plate, and four pairs were fixed using the gliding plate with bone cement augmentation of its proximal screws. The specimens were cyclically tested under progressively increasing loading until perforation of a screw. Telescoping of a screw, varus tilting and screw migration were recorded using optical motion tracking.

Results

Mean initial stiffness (N/mm) was 581.3 (sd 239.7) for the gliding plate, 631.5 (sd 160.0) for the PHILOS and 440.2 (sd 97.6) for the gliding augmented plate without significant differences between the groups (p = 0.11). Mean varus tilting (°) after 7500 cycles was comparable between the gliding plate (2.6; sd 1.9), PHILOS (1.2; sd 0.6) and gliding augmented plate (1.7; sd 0.9) (p = 0.10). Similarly, mean screw migration(mm) after 7500 cycles was similar between the gliding plate (3.02; sd 2.85), PHILOS (1.30; sd 0.44) and gliding augmented plate (2.83; sd 1.18) (p = 0.13). Mean number of cycles until failure with 5° varus tilting were 12702 (sd 3687) for the gliding plate, 13948 (sd 1295) for PHILOS and 13189 (sd 2647) for the gliding augmented plate without significant differences between the groups (p = 0.66).

Conclusion

Biomechanically, plate fixation using a new gliding screw technology did not show considerable advantages in comparison with fixation using a standard PHILOS plate. Based on the finding of telescoping of screws, however, it may represent a valid approach for further investigations into how to avoid the cut-out of screws.

Cite this article: Y. P. Acklin, I. Zderic, J. A. Inzana, S. Grechenig, R. Schwyn, R. G. Richards, B. Gueorguiev. Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures. Bone Joint Res 2018;7:422–429. DOI: 10.1302/2046-3758.76.BJR-2017-0356.R1.

[Intramedullary claw for stabilization of proximal humerus fractures: a comparison with other semirigid techniques]

Proximal humerus fractures (pHF) are common. In this retrospective study intra-operative and postoperative data and complications of patients stabilized with conventional semirigid techniques (pins, n=30; helix wire, n=19) or a novel semirigid technique, the intramedullary claw (IMC, n=82) were compared. The type and frequency of postoperative complications differed between the groups (p<0.001). The IMC is a novel semirigid technique to stabilize pHF and seems to result in fewer complications than pins or helix wire. The frequency and relevance of a loss of repositioning in patients after IMC implantation need to be elucidated in long-term studies.

The treatment of dislocated humeral head fractures with a new proximal intramedullary nail system

A new proximal humerus nail (Sirus) for the treatment of proximal humerus fractures has become available. This paper presents the clinical and radiological outcome of the first collective study of 36 patients. Evaluation was performed prospectively. An antero-acromial approach was used for all patients. Three fixed-angle screws were inserted in a locking technique. Thirty-six fractures were fixed with the Sirus nail. These were dislocated 2- and 3-part fractures as described by Neer (J Bone Joint Surg 52:1077-1089). Outcomes were evaluated using the Constant score. Of the 36 patients evaluated 23 had sustained a 2-part fracture and 13 a 3-part fracture. The average age at surgery was 71.2 years (range, 30-93). In 75% of the cases, good to very good outcomes were achieved. Outcomes were satisfactory in 13.8% of the cases. Twenty-five fractures were treated in a closed technique. Average operating time was 41 minutes (range, 19-106) with a fluoroscopy time of 0.6 minutes (range, 0.4-2.6). Secondary fragment dislocation occurred in two cases. After 12.1 months the average Constant score was 79.2 (range, 46-100). Initial clinical experience with the Sirus nail indicates that the procedure is straightforward and has a low complication rate. Functional outcomes are predominantly good to very good. Large fragments of the greater tuberosity and 4-part fractures are beyond the scope of this application.