The properties of impacted morsellised bone graft (MBG) in revision total knee arthroplasty (TKA) were studied in 12 horses. The left hind metatarsophalangeal joint was replaced by a human TKA. The horses were then randomly divided into graft and control groups. In the graft group, a unicondylar, lateral uncontained defect was created in the third metatarsal bone and reconstructed using autologous MBG before cementing the TKA. In the control group, a cemented TKA was implanted without the bone resection and grafting procedure. After four to eight months, the animals were killed and a biomechanical loading test was performed with a cyclic load equivalent to the horse’s body-weight to study mechanical stability. After removal of the prosthesis, the distal third metatarsal bone was studied radiologically, histologically and by quantitative and micro CT. Biomechanical testing showed that the differences in deformation between the graft and the control condyles were not significant for either elastic or time-dependent deformations. The differences in bone mineral density (BMD) between the graft and the control condyles were not significant. The BMD of the MBG was significantly lower than that in the other regions in the same limb. Micro CT showed a significant difference in the degree of anisotropy between the graft and host bone, even although the structure of the area of the MBG had trabecular orientation in the direction of the axial load. Histological analysis revealed that all the grafts were revascularised and completely incorporated into a new trabecular structure with few or no remnants of graft. Our study provides a basis for the clinical application of this technique with MBG in revision TKA

The treatment of large bony defects by callus distraction is well accepted, but the duration of treatment is long and the rate of complications increases accordingly. We have examined the effect of the stiffness of the axial fixator on reducing the time for maturation of callus. We created a mid-diaphyseal defect of 15 mm in the metatarsal bone in sheep and stabilised it with a ring fixator. After four days a bony segment was transported for 16 days at 1 mm per day. After 64 days the animals were divided into four groups, three with axial interfragmentary movement (IFM) of 0.5, 1.2 and 3.0 mm, respectively, and a control group. The 3.0 mm IFM group had the smallest bone density (p = 0.001) and area of callus and the largest IFM after 12 weeks; it also had typical clinical signs of hypertrophic nonunion. The most rapid stiffening of the callus was in the 0.5 mm group which had the smallest IFM (p = 0.04) after 12 weeks and radiological signs of bridging of the defect. These results indicate that suitable dynamic axial stimulation can enhance maturation of distraction callus when the initial amplitude is small, but that a large IFM can lead to delayed union

A cavovarus foot deformity was simulated in cadaver specimens by inserting metallic wedges of 15° and 30° dorsally into the first tarsometatarsal joint. Sensors in the ankle joint recorded static tibiotalar pressure distribution at physiological load.

The peak pressure increased significantly from neutral alignment to the 30° cavus deformity, and the centre of force migrated medially. The anterior migration of the centre of force was significant for both the 15° (repeated measures analysis of variance (ANOVA), p = 0.021) and the 30° (repeated measures ANOVA, p = 0.007) cavus deformity. Differences in ligament laxity did not influence the peak pressure.

These findings support the hypothesis that the cavovarus foot deformity causes an increase in anteromedial ankle joint pressure leading to anteromedial arthrosis in the long term, even in the absence of lateral hindfoot instability.

Compartment syndrome of the foot requires urgent surgical treatment. Currently, there is still no agreement on the number and location of the myofascial compartments of the foot. The aim of this cadaver study was to provide an anatomical basis for surgical decompression in the event of compartment syndrome. We found that there were three tough vertical fascial septae that extended from the hindfoot to the midfoot on the plantar aspect of the foot. These septae separated the posterior half of the foot into three compartments. The medial compartment containing the abductor hallucis was surrounded medially by skin and subcutaneous fat and laterally by the medial septum. The intermediate compartment, containing the flexor digitorum brevis and the quadratus plantae more deeply, was surrounded by the medial septum medially, the intermediate septum laterally and the main plantar aponeurosis on its plantar aspect. The lateral compartment containing the abductor digiti minimi was surrounded medially by the intermediate septum, laterally by the lateral septum and on its plantar aspect by the lateral band of the main plantar aponeurosis. No distinct myofascial compartments exist in the forefoot.

Based on our findings, in theory, fasciotomy of the hindfoot compartments through a modified medial incision would be sufficient to decompress the foot.

Strains applied to bone can stimulate its development and adaptation. High strains and rates of strain are thought to be osteogenic, but the specific dose response relationship is not known. In vivo human strain measurements have been performed in the tibia to try to identify optimal bone strengthening exercises for this bone, but no measurements have been performed in the distal radial metaphysis, the most frequent site of osteoporotic fractures. Using a strain gauged bone staple, in vivo dorsal metaphyseal radial strains and rates of strain were measured in ten female patients during activities of daily living, standard exercises and falls on extended hands. Push-ups and falling resulted in the largest compression strains (median 1345 to 3146 με, equivalent to a 0.1345% to 0.3146% length change) and falling exercises in the largest strain rates (18 582 to 45 954 με/s). On the basis of their high strain and/or strain rates these or variations of these exercises may be appropriate for distal radial metaphyseal bone strengthening.

We have evaluated four different fixation techniques for the reconstruction of a standard Mason type-III fracture of the radial head in a sawbone model. The outcome measurements were the quality of the reduction, and stability.

A total of 96 fractures was created. Six surgeons were involved in the study and each reconstructed 16 fractures with 1.6 mm fine-threaded wires (Fragment Fixation System (FFS)), T-miniplates, 2 mm miniscrews and 2 mm Kirschner (K-) wires; four fractures being allocated to each method using a standard reconstruction procedure.

The quality of the reduction was measured after definitive fixation. Biomechanical testing was performed using a transverse plane shear load in two directions to the implants (parallel and perpendicular) with respect to ultimate failure load and displacement at 50 N.

A significantly better quality of reduction was achieved using the FFS wires (Tukey’s post hoc tests, p < 0.001) than with the other devices with a mean step in the articular surface and the radial neck of 1.04 mm (sd 0.96) for the FFS, 4.25 mm (sd 1.29) for the miniplates, 2.21 mm (sd 1.06) for the miniscrews and 2.54 mm (sd 0.98) for the K-wires. The quality of reduction was similar for K-wires and miniscrews, but poor for miniplates.

The ultimate failure load was similar for the FFS wires (parallel, 196.8 N (sd 46.8), perpendicular, 212.5 N (sd 25.6)), miniscrews (parallel, 211.8 N (sd 47.9), perpendicular, 208.0 N (sd 65.9)) and K-wires (parallel, 200.4 N (sd 54.5), perpendicular, 165.2 N (sd 37.9)), but significantly worse (Tukey’s post hoc tests, p < 0.001) for the miniplates (parallel, 101.6 N (sd 43.1), perpendicular, 122.7 N (sd 40.7)). There was a significant difference in the displacement at 50 N for the miniplate (parallel, 4.8 mm (sd 2.8), perpendicular, 4.8 mm (sd 1.7)) vs FFS (parallel, 2.1 mm (sd 0.8), perpendicular, 1.9 mm (sd 0.7)), miniscrews (parallel, 1.8 mm (sd 0.5), perpendicular, 2.3 mm (sd 0.8)) and K-wires (parallel, 2.2 mm (sd 1.8), perpendicular, 2.4 mm (sd 0.7; Tukey’s post hoc tests, p < 0.001)).

The fixation of a standard Mason type-III fracture in a sawbone model using the FFS system provides a better quality of reduction than that when using conventional techniques. There was a significantly better stability using FFS implants, miniscrews and K-wires than when using miniplates.