Cartilage diseases have a significant impact on the patient's quality of life and are a heavy burden for the healthcare system. Better understanding, early detection and proper follow-up could improve quality of life and reduce healthcare related costs. Therefore, the aim of this study was to evaluate if difference between osteoarthritic (OA) and non-osteoarthritic (non-OA) knees can be detected quantitatively on cartilage and subchondral bone levels with advanced but clinical available imaging techniques.

Two OA (mean age = 88.3 years) and three non-OA (mean age = 51.0 years) human cadaveric knees were scanned two times. A high-resolution peripheral quantitative computed tomography (HR-pQCT) scan (XtremeCT, Scanco Medical AG, Switzerland) was performed to quantify the bone microstructure. A contrast-enhanced clinical CT scan (GE Revolution Evo, GE Medical Systems AG, Switzerland) was acquired with the contrast agent Visipaque 320 (60 ml) to measure cartilage. Subregions dividing the condyle in four parts were identified semi-automatically and the images were segmented using adaptive thresholding. Microstructural parameters of subchondral bone and cartilage thickness were quantified.

The overall cartilage thickness was reduced by 0.27 mm between the OA and non-OA knees and the subchondral bone quality decreased accordingly (reduction of 33.52 % in BV/TV in the layer from 3 to 8 mm below the cartilage) for the femoral medial condyle. The largest differences were observed at the medial part of the femoral medial condyle both for cartilage and for bone parameters, corresponding to clinical observations.

Subchondral bone microstructural parameters and cartilage thickness were quantified using in vivo available imaging and apparent differences between the OA and non-OA knees were detected. Those results may improve OA follow-up and diagnosis and could lead to a better understanding of OA. However, further in vivo studies are needed to validate these methods in clinical practice.

Reorientating pelvic osteotomies are performed to improve femoral head coverage and secondary degenerative arthritis. A rectangular triple pelvic innominate osteotomy (3PIO) is performed in symptomatic cases. However, deciding optimal screw fixation type to avoid complications is questionable. Therefore, this study aimed to investigate the biomechanical behavior of two different acetabular screw configurations used for rectangular 3PIO osteosynthesis. It was hypothesized that bi-directional screw fixation would be biomechanically superior to mono-axial screw fixation technique.

A rectangular 3PIO was performed in twelve right-side artificial Hemi-pelvises. Group 1 (G1) had two axial and one transversal screw in a bi-directional orientation. Group 2 (G2) had three screws in the axial direction through the iliac crest. Acetabular fragment was reoriented to 10.5° inclination in coronal plane, and 10.0° increased anteversion along axial plane. Specimens were biomechanically tested until failure under progressively increasing cyclic loading at 2Hz, starting at 50N peak compression, increasing 0.05N/cycle. Stiffness was calculated from machine data. Acetabular anteversion, inclination and medialization were evaluated from motion tracking data from 250-2500 at 250 cycle increments. Failure cycles and load were evaluated for 5° change in anteversion.

Stiffness was higher in G1 (56.46±19.45N/mm) versus G2 (39.02±10.93N/mm) but not significantly, p=0.31. Acetabular fragment anteversion, inclination and medialization increased significantly each group (p≤0.02) and remained non-significantly different between the groups (p≥0.69). Cycles to failure and failure load were not significantly different between G1 (4406±882, 270.30±44.10N) and G2 (5059±682, 302.95±34.10N), p=0.78.

From a biomechanical perspective, the present study demonstrates that a bi-directional screw orientation does not necessarily advantageous versus mono-axial alignment when the latter has all three screws evenly distributed over the osteotomy geometry. Moreover, the 3PIO fixation is susceptible to changes in anteversion, inclination and medialization of the acetabular fragment until the bone is healed. Therefore, cautious rehabilitation with partial weight-bearing is recommended.

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.

Proximal humerus fractures (PHF) are the third most common fractures in the elderly. Treatment of complex PHF has remained challenging with mechanical failure rates ranging up to 35% even when state-of-the-art locked plates are used. Secondary (post-operative) screw perforation through the articular surface of the humeral head is the most frequent mechanical failure mode, with rates up to 23%. Besides other known risk factors, such as non-anatomical reduction and lack of medial cortical support, in-adverse intraoperative perforation of the articular surfaces during pilot hole drilling (overdrilling) may increase the risk of secondary screw perforation. Overdrilling often occurs during surgical treatment of osteoporotic PHF due to minimal tactile feedback; however, the awareness in the surgical community is low and the consequences on the fixation stability have remained unproved. Therefore, the aim of this study was to evaluate biomechanically whether overdrilling would increase the risk of cyclic screw perforation failure in unstable PHF.

A highly unstable malreduced 3-part fracture was simulated by osteotomizing 9 pairs of fresh-frozen human cadaveric proximal humeri from elderly donors (73.7 ± 13.0 ys, f/m: 3/6). The fragments were fixed with a locking plate (PHILOS, DePuy Synthes, Switzerland) using six proximal screws, with their lengths selected to ensure 6 mm tip-to-joint distance. The pairs were randomized into two treatment groups, one with all pilot holes accurately predrilled (APD) and another one with the boreholes of the two calcar screws overdrilled (COD). The constructs were tested under progressively increasing cyclic loading to failure at 4 Hz using a previously developed setup and protocol. Starting from 50 N, the peak load was increased by 0.05 N/cycle. The event of initial screw loosening was defined by the abrupt increase of the displacement at valley load, following its initial linear behavior. Perforation failure was defined by the first screw penetrating the joint surface, touching the artificial glenoid component and stopping the test via electrical contact.

Bone mineral density (range: 63.8 – 196.2 mgHA/cm3) was not significantly different between the groups. Initial screw loosening occurred at a significantly lower number of cycles in the COD group (10,310 ± 3,575) compared to the APD group (12,409 ± 4,569), p = 0.006. Number of cycles to screw perforation was significantly lower for the COD versus APD specimens (20,173 ± 5,851 and 24,311 ± 6,318, respectively), p = 0.019. Failure mode was varus collapse combined with lateral-inferior translation of the humeral head. The first screw perforating the articular surface was one of the calcar screws in all but one specimen.

Besides risk factors such as fracture complexity and osteoporosis, inadequate surgical technique is a crucial contributor to high failure rates in locked plating of complex PHF. This study shows for the first time that overdrilling of pilot holes can significantly increase the risk of secondary screw perforation. Study limitations include the fracture model and loading method. While the findings require clinical corroboration, raising the awareness of the surgical community towards this largely neglected risk source, together with development of devices to avoid overdrilling, are expected to help improve the treatment outcomes.

Distal radius fractures have an incidence rate of 17.5% among all fractures. Their treatment in case of comminution, commonly managed by volar locking plates, is still challenging. Variable-angle screw technology could counteract these challenges. Additionally, combined volar and dorsal plate fixation is valuable for treatment of complex fractures at the distal radius. Currently, biomechanical investigation of the competency of supplemental dorsal plating is scant. The aim of this study was to investigate the biomechanical competency of double-plated distal radius fractures in comparison to volar locking plate fixation.

Complex intra-articular distal radius fractures AO/OTA 23-C 2.1 and C 3.1 were created by means of osteotomies, simulating dorsal defect with comminution of the lunate facet in 30 artificial radii, assigned to 3 study groups with 10 specimens in each. The styloid process of each radius was separated from the shaft and the other articular fragments. In group 1, the lunate facet was divided to 3 equally-sized fragments. In contrast, the lunate in group 2 was split in a smaller dorsal and a larger volar fragment, whereas in group 3 was divided in 2 equal fragments. Following fracture reduction, each specimen was first instrumented with a volar locking plate and non-destructive quasi-static biomechanical testing under axial loading was performed in specimen's inclination of 40° flexion, 40° extension and 0° neutral position. Mediolateral radiographs were taken under 100 N loads in flexion and extension, as well as under 150 N loads in neutral position. Subsequently, all biomechanical tests were repeated after supplemental dorsal locking plate fixation of all specimens. Based on machine and radiographic data, stiffness and angular displacement between the shaft and lunate facet were determined.

Stiffness in neutral position (N/mm) without/with dorsal plating was on average 164.3/166, 158.5/222.5 and 181.5/207.6 in groups 1–3. It increased significantly after supplementary dorsal plating in groups 2 and 3.

Predominantly, from biomechanical perspective supplemental dorsal locked plating increases fixation stability of unstable distal radius fractures after volar locked plating. However, its effect depends on the fracture pattern at the distal radius.