This study investigated the quality and quantity of healing of a bone defect following intramedullary reaming undertaken by two fundamentally different systems; conventional, using non-irrigated, multiple passes; or suction/irrigation, using one pass. The result of a measured re-implantation of the product of reaming was examined in one additional group. We used 24 Swiss mountain sheep with a mean tibial medullary canal diameter between 8 mm and 9 mm. An 8 mm ‘napkin ring’ defect was created at the mid-diaphysis. The wound was either surgically closed or occluded. The medullary cavity was then reamed to 11 mm. The Reamer/Irrigator/Aspirator (RIA) System was used for the reaming procedure in groups A (RIA and autofilling) and B (RIA, collected reamings filled up), whereas reaming in group C (Synream and autofilling) was performed with the Synream System. The defect was allowed to auto-fill with reamings in groups A and C, but in group B, the defect was surgically filled with collected reamings. The tibia was then stabilised with a solid locking Unreamed Humerus Nail (UHN), 9.5 mm in diameter. The animals were killed after six weeks. After the implants were removed, measurements were taken to assess the stiffness, strength and callus formation at the site of the defect.

There was no significant difference between healing after conventional reaming or suction/irrigation reaming. A significant improvement in the quality of the callus was demonstrated by surgically placing captured reamings into the defect using a graft harvesting system attached to the aspirator device. This was confirmed by biomechanical testing of stiffness and strength. This study suggests it could be beneficial to fill cortical defects with reaming particles in clinical practice, if feasible.

We investigated several factors which affect the stability of cortical screws in osteoporotic bone using 18 femora from cadavers of women aged between 45 and 96 years (mean 76). We performed bone densitometry to measure the bone mineral density of the cortical and cancellous bone of the shaft and head of the femur, respectively. The thickness and overall bone mass of the cortical layer of the shaft of the femur were measured using a microCT scanner. The force required to pull-out a 3.5 mm titanium cortical bone screw was determined after standardised insertion into specimens of the cortex of the femoral shaft.

A significant correlation was found between the pull-out strength and the overall bone mass of the cortical layer (r² = 0.867, p < 0.01) and also between its thickness (r² = 0.826, p < 0.01) and bone mineral density (r² = 0.861, p < 0.01). There was no statistically significant correlation between the age of the donor and the pull-out force (p = 0.246), the cortical thickness (p = 0.199), the bone mineral density (p = 0.697) or the level of osteoporosis (p = 0.378).

We conclude that the overall bone mass, the thickness and the bone mineral density of the cortical layer, are the main factors which affect the stability of a screw in human female osteoporotic cortical bone.

Despite advances in the prevention and treatment of osteoporotic fractures, their prevalence continues to increase. Their operative treatment remains a challenge for the surgeon, often with unpredictable outcomes. This review highlights the current aspects of management of these fractures and focuses on advances in implant design and surgical technique.

Aims: The holding power of new designed implants, need to be improved by osseointegration, in particular in osteoporotic bone. The osseo-integration depends on the interface mechanical conditions during fracture healing or fusion leading either to bony incorporation or to micro-movement and encapsulation. The aim of the current study was to evaluate the load sharing conditions after the fusion process between implant and bone with respect to the fusion status of the stabilized segment. Methods: The hollow cylinder based implant was used to stabilize a corpectomy of L4 in 17 sheep (9 osteoporotic and 8 control). After a survival time of 4 month the spine specimens were tested in a six-degree-of-freedom (6DOF) device in the three principal directions (flex/ex, lat. bending, torsion). Hysteresis curves were recorded before and after removal of the stabilizing longitudinal bar. The changes in ROM and stiffness in the different planes were compared statistically (α < 0.05). The results were validated histologically. Results: The increase in range of motion in all planes was significantly higher after implant removal in animals that were classified as non-fused spines (+35±15% in non-fused vs. +12±8% in fused spines). At the same time stiffness decreased significantly more (stiffness ex/flex −31±14% in non-fused vs −7±7% in fused spines) without differnces between normal and osteoporotic spines. Histology revealed 3 capsules in the fused spines. Conclusions: If fusion takes place in the presence of a relatively stiff implant the load flow through the implant is interrupted by connective tissue on one of the implant/bone interfaces. The changes in ROM and stiffness indicate the remaining contribution of the implant to the load sharing of the implant/ bone complex in case of non-fusion and are highly sensitive therefore to predict micromovement.