Biomechanical analysis of dorsal plate fixation in proximal phalangeal fractures

A systematic review of the use of titanium versus stainless steel implants for fracture fixation

Background:

Controversy exists regarding the use of titanium and stainless steel implants in fracture surgery. To our knowledge, no recent, comprehensive review on this topic has been reported.

Purpose:

To perform a systematic review of the evidence in the current literature comparing differences between titanium and stainless steel implants for fracture fixation.

Methods:

A systematic review of original research articles was performed through the PubMed database using PRISMA guidelines. Inclusion criteria were English-language studies comparing titanium and stainless steel implants in orthopaedic surgery, and outcome data were extracted.

Results:

The search returned 938 studies, with 37 studies meeting our criteria. There were 12 clinical research articles performed using human subjects, 11 animal studies, and 14 biomechanical studies. Clinical studies of the distal femur showed the stainless steel cohorts had significantly decreased callus formation and an increased odds radio (OR 6.3, 2.7-15.1; P < .001) of nonunion when compared with the titanium plate cohorts. In the distal radius, 3 clinical trials showed no implant failures in either group, and no difference in incidence of plate removal, or functional outcome. Three clinical studies showed a slightly increased odds ratio of locking screw breakage with stainless steel intramedullary nails compared with titanium intramedullary nails (OR 1.52, CI 1.1-2.13).

Conclusion:

Stainless steel implants have equal or superior biomechanical properties when compared with titanium implants. However, there is clinical evidence that titanium plates have a lower rate of failure and fewer complications than similar stainless steel implants in some situations. Although our review supports the use of titanium implants in these clinical scenarios, we emphasize that further prospective, comparative clinical studies are required before the conclusions can be made.

The role of locking technology in the hand

Locked fixed-angle plating in the hand and wrist helps to optimize outcomes following surgical fixation of select acute fractures and complex reconstructions. Select indications include unstable distal ulna head/neck fractures, periarticular metacarpal and phalangeal fractures, comminuted/multifragmentary diaphyseal fractures with bone loss (ie, combined injuries of the hand), osteopenic/pathologic fractures, nonunions and corrective osteotomy fixation, and small joint arthrodesis. Locked plating techniques in the hand should not be seen as a panacea for wrist and digital acute trauma and delayed reconstructions. An understanding of the biomechanics of fixed-angle plating and proper technical application of locking constructs will optimize outcomes and minimize complications. As clinical experience with locking technology in hand trauma broadens, new indications and applications will emerge. Currently, several systems are available. The specific implants share common features in their protocols for insertion, but unique differences in their design (ie, individual locking mechanisms, uniaxial vs polyaxial locking capability, metallurgy, and plate profiles) must be appreciated and considered preoperatively.

Self-tapping versus standard tapped titanium screw fixation in the upper extremity

Most screws used in fracture fixation necessitate a separate step for tapping of the screw hole. Titanium screw systems have been developed in which the screws can be inserted directly after a drill hole is made. These self-tapping screws thereby eliminate an operative step. A retrospective study was conducted that evaluated all wrist and hand procedures performed between January 1992 and December 1994 by 1 surgeon using screw fixation. The results of 39 cases treated with standard tapped titanium screws were compared with 28 cases treated with self-tapping titanium screws. Nearly identical union and complication rates were obtained in each group. Comparable results can be obtained with self-tapping screw fixation, which limits the number of instruments needed, eliminates an operative step, and thereby may diminish operative risk and shorten operative time.

A comparative mechanical analysis of plate fixation in a proximal phalangeal fracture model

A biomechanical study compared the mechanical properties of hand and craniofacial plating systems commonly used in proximal phalangeal fractures. Two plates of each of the various systems were mounted dorsally on a yellow-birch-dowel model of a proximal phalanx after a transverse cut was made in the middle of the section of the dowel, modeling a midshaft transverse osteotomy or fracture. Torsional rigidity, as well as four-point bending rigidity in apex dorsal, lateral and volar directions, was achieved. Failure testing in apex palmar four-point bending was then examined. Between plating systems, torsion varied 1,600% and results of apex palmar testing varied 1,500%. Apex palmar moment-to-failure testing varied 1,000% and represented a 3.5%-38% range of intact proximal phalangeal strength. This also represented 12%-128% of the maximum calculated in vivo bending moments of the proximal phalanx. The wide variation in plate strengths and stiffness raises questions as to the suitability of certain plating systems with regard to early mobilization. Moreover, some plating systems tested were mechanically weaker than the reported strengths of certain Kirschner wire fixation techniques.

A comparative study of miniplates used in the treatment of mandibular fractures

The purposes of this study were to investigate the differences in mechanical properties of major miniplating systems used for noncompression miniplate osteosynthesis of mandibular fractures and to determine whether these properties influence treatment outcome. The study was conducted in two parts. First, six of the major miniplate systems currently used at the Royal Adelaide Hospital were subjected to bending tests at the University of Adelaide Engineering Department to quantify the relative stiffness of each plate. Second, a prospective sample of patients presenting with mandibular fractures was analyzed. These patients were treated with a variety of the miniplating systems. The results of treatment as a whole were compared to identify any direct benefit consequent on the miniplate selected. While significant differences in stiffness were identified between the plating systems, no significant differences in treatment outcome were identified, between the noncompression plates employed. Since no observable benefits have been identified by choice of miniplate, selection should be based on surgical preference, biocompatibility, CT compatibility and unit cost. Because of the variations in materials, design, properties, CT compatibility, and unit cost, it is important not to regard all miniplates as equal and interchangeable.