Implant removal after clavicle plating is common. Low-profile dual mini-fragment plate constructs are considered safe for fixation of diaphyseal clavicle fractures. The aim of this study was to investigate: (1) the biomechanical competence of different dual plate designs from stiffness and cycles to failure, and (2) to compare them against 3.5mm single superoanterior plating.

Twelve artificial clavicles were assigned to 2 groups and instrumented with titanium matrix mandible plates as follows: group 1 (G1) (2.5mm anterior+2.0mm superior) and group 2 (G2) (2.0mm anterior+2.0mm superior). An unstable clavicle shaft fracture (AO/OTA15.2C) was simulated. Specimens were cyclically tested to failure under craniocaudal cantilever bending, superimposed with torsion around the shaft axis and compared to previous published data of 6 locked superoanterior plates tested under the same conditions (G3).

Displacement (mm) after 5000 cycles was highest in G3 (10.7±0.8) followed by G2 (8.5±1.0) and G1 (7.5±1.0), respectively. Both outcomes were significantly higher in G3 as compared to both G1 and G2 (p≤0.027). Cycles to failure were highest in G3 (19536±3586) followed by G1 (15834±3492) and G2 (11104±3177), being significantly higher in G3 compared to G2 (p=0.004). Failure was breakage of one or two plates at the level of the osteotomy in all specimens. One G1 specimen demonstrated failure of the anterior plate. Both plates in other G1 specimens. Majority of G2 had fractures in both plates. No screw pullout or additional clavicle fractures were observed among specimens.

Low-profile 2.0/2.0 dual plates demonstrated similar initial stiffness compared to 3.5mm single plates, however, had significantly lower failure endurance. Low-profile 2.5/2.0 dual plates showed significant higher initial stiffness and similar resistance to failure compared to 3.5mm single locked plates and can be considered as a useful alternative for diaphyseal clavicle fracture fixation. These results complement the promising results of several clinical studies.

Introduction and Objective

Malunion after trauma can lead to coronal plane malalignment in the lower limb. The mechanical hypothesis suggests that this alters the load distribution in the knee joint and that that this increased load may predispose to compartmental arthritis. This is generally accepted in the orthopaedic community and serves as the basis guiding deformity correction after malunion as well as congenital or insidious onset malalignment. Much of the literature surrounding the contribution of lower limb alignment to arthritis comes from cohort studies of incident osteoarthritis. There has been a causation dilemma perpetuated in a number of studies - suggesting malalignment does not contribute to, but is instead a consequence of, compartmental arthritis. In this investigation the relationship between compartmental (medial or lateral) arthritis and coronal plane malalignment (varus or valgus) in patients with post traumatic unilateral limb deformity was examined. This represents a specific niche cohort of patients in which worsened compartmental knee arthritis after extra-articular injury must rationally be attributed to malalignment.