Locking plate fixation with and without inferomedial screws for proximal humeral fractures: a biomechanical study.

PURPOSE. To compare the efficacy of locking plate fixation with and without inferomedial screws in maintaining the reduction of a proximal humeral fracture. METHODS. 22 synthetic humerus models were used. A standardised 3-part proximal humeral fracture with a 4-mm wedge segment was created and fixed with a locking plate and screws with (n=11) and without (n=11) inferomedial screws. The intrafragmentary motion of the construct at 250, 500, 750, and 1000 cycles of 532 N loading, and the load to failure of the 2 groups were compared. RESULTS. Locking plate fixation with inferomedial screws reduced the mean intrafragmentary motion in all cycles (

An application of principal component analysis to the clavicle and clavicle fixation devices

BACKGROUND: Principal component analysis (PCA) enables the building of statistical shape models of bones and joints. This has been used in conjunction with computer assisted surgery in the past. However, PCA of the clavicle has not been performed. Using PCA, we present a novel method that examines the major modes of size and three-dimensional shape variation in male and female clavicles and suggests a method of grouping the clavicle into size and shape categories. MATERIALS AND METHODS: Twenty-one high-resolution computerized tomography scans of the clavicle were reconstructed and analyzed using a specifically developed statistical software package. After performing statistical shape analysis, PCA was applied to study the factors that account for anatomical variation. RESULTS: The first principal component representing size accounted for 70.5 percent of anatomical variation. The addition of a further three principal components accounted for almost 87 percent. Using statistical shape analysis, clavicles in males have a greater lateral depth and are longer, wider and thicker than in females. However, the sternal angle in females is larger than in males. PCA confirmed these differences between genders but also noted that men exhibit greater variance and classified clavicles into five morphological groups. DISCUSSION AND CONCLUSIONS: This unique approach is the first that standardizes a clavicular orientation. It provides information that is useful to both, the biomedical engineer and clinician. Other applications include implant design with regard to modifying current or designing future clavicle fixation devices. Our findings support the need for further development of clavicle fixation devices and the questioning of whether gender-specific devices are necessary

Effect of calcium triphosphate cement on proximal humeral fracture osteosynthesis: a finite element analysis

Purpose. To measure the effect of void-filling calcium triphosphate cement on the loads at the implant-bone interface of a proximal humeral fracture osteosynthesis using a finite element analysis. Methods. Finite element models of a 3-part proximal humeral fracture fixed with a plate with and without calcium triphosphate cement augmentation were generated from a quantitative computed tomography dataset of an intact proximal humerus. Material properties were assigned to bone fragments using published expressions relating Young\u27s modulus to local Hounsfield number. Boundary conditions were then applied to the model to replicate the physiological loads. The effect of void-filling calcium triphosphate cement was analysed. Results. When the void was filled with calcium triphosphate cement, the pressure gradient of the bone surrounding the screws in the medial fracture fragment decreased 97% from up to 21.41 to 0.66 MPa. Peak pressure of the fracture planes decreased 95% from 6.10 to 0.30 MPa and occurred along the medial aspect. The mean stress in the screw locking mechanisms decreased 78% from 71.23 to 15.92 MPa. The angled proximal metaphyseal screw had the highest stress. Conclusion. Augmentation with calcium triphosphate cement improves initial stability and reduces stress on the implant-bone interface

An application of principal component analysis to the clavicle and clavicle fixation devices

Abstract Background Principal component analysis (PCA) enables the building of statistical shape models of bones and joints. This has been used in conjunction with computer assisted surgery in the past. However, PCA of the clavicle has not been performed. Using PCA, we present a novel method that examines the major modes of size and three-dimensional shape variation in male and female clavicles and suggests a method of grouping the clavicle into size and shape categories. Materials and methods Twenty-one high-resolution computerized tomography scans of the clavicle were reconstructed and analyzed using a specifically developed statistical software package. After performing statistical shape analysis, PCA was applied to study the factors that account for anatomical variation. Results The first principal component representing size accounted for 70.5 percent of anatomical variation. The addition of a further three principal components accounted for almost 87 percent. Using statistical shape analysis, clavicles in males have a greater lateral depth and are longer, wider and thicker than in females. However, the sternal angle in females is larger than in males. PCA confirmed these differences between genders but also noted that men exhibit greater variance and classified clavicles into five morphological groups. Discussion And Conclusions This unique approach is the first that standardizes a clavicular orientation. It provides information that is useful to both, the biomedical engineer and clinician. Other applications include implant design with regard to modifying current or designing future clavicle fixation devices. Our findings support the need for further development of clavicle fixation devices and the questioning of whether gender-specific devices are necessary.</p

Upper limb strength and performance deficits after glenohumeral joint stabilisation surgery in contact and collision athletes

Purpose: The primary aim was to identify and quantify differences in interlimb asymmetry magnitudes across a battery of upper extremity strength and performance tests at four and six months after glenohumeral-joint-stabilisation surgery shoulder stabilisation in contact and collision athletes compared to an un-injured group. A secondary aim was to investigate if identified asymmetry magnitudes changed from four months to six months post glenohumeral-joint-stabilisation. The third aim was to explore associations within the different performance and strength variables. Methods: Fifty-six male contact and collision sport athletes who had had undergone unilateral glenohumeral-joint-stabilisation were tested at 4 and 6 months post-surgery. An un-injured control group (n=39 for upper extremity performance tests, n= 47 for isokinetic dynamometry) were tested on a single occasion. Three upper extremity force platform-based performance tests and angle-specific concentric internal and external isokinetic shoulder rotational strength were assessed, and inter-limb asymmetries were compared between the two groups. Results: At four months post-surgery, the glenohumeral-joint-stabilisation group demonstrated significantly higher absolute interlimb asymmetry values than the un-injured group for almost all the performance test variables. In the ballistic upper-body performance tests, the glenohumeral-joint-stabilisation group achieved only half the body elevation reached by the un-injured (counter-movement push-up jump height (η2 = 0.50) and press-jump jump height (η2 = 0.39)). At 6 months post-surgery absolute inter-limb asymmetries reduced for the performance tests variables but some asymmetry persisted. The glenohumeral-joint-stabilisation group had significantly greater absolute inter-limb asymmetries for five out of the eight isokinetic variables. Conclusions: Contact and collision athletes who may be cleared to return to sport at four to six months after glenohumeral-joint-stabilisation surgery shoulder stabilisation continue to demonstrate upper limb strength and performance deficits when compared to their un-injured limb and to their un-injured counterparts

DS_10.1177_0363546518759540 – Supplemental material for Open Versus Arthroscopic Latarjet Procedure for Anterior Shoulder Instability: A Systematic Review and Meta-analysis

<p>Supplemental material, DS_10.1177_0363546518759540 for Open Versus Arthroscopic Latarjet Procedure for Anterior Shoulder Instability: A Systematic Review and Meta-analysis by Eoghan T. Hurley, Daren Lim Fat, Shane K. Farrington and Hannan Mullett in The American Journal of Sports Medicine</p