We retrospectively studied the functional and oncological results of 15 patients after reconstruction of the distal radius with osteoarticular allograft or non-vascularised fibular graft following wide excision of an aggressive benign or malignant tumour. Eight patients underwent osteoarticular allograft and seven patients had a non-vascularised autogenous fibular graft reconstruction. The average time for incorporation of the graft was 6 and 5 months in each reconstruction respectively. There was no tumour recurrence after follow up over 41.5-95.5 (average 60.5) months. All patients had good and excellent functional results. Three patients in the group reconstructed with osteoarticular allograft had plate loosening and graft fractures which were successfully treated subsequently.

One of the major failure modes of cementless acetabular components is the loosening of the acetabular cup, which is mostly attributable to insufficient initial stability. A hemispherical cup with a porous coating which is inserted with press-fit fixation and secured with several screws is one of the most widely used approaches. Many studies have found that bone screws are very helpful aids for cup fixation, but the optimal surgical technique for inserting screws has not been clearly reported. In this study, hemispherical cups were fixed into blocks of foam bone with zero to three screws. The effects of three types of screw eccentricity (a 1-mm offset and angular eccentricities of 15°and 25°) on the initial stability of the acetabular cup were evaluated. The experimental results indicate that increasing the number of screws enhances the cup stability in the case of ideal screwing (i.e., with no eccentricity). An angular eccentricity of 15°did not affect the cup stability for fixation with one or two screws. However, the presence of 25°of angular eccentricity significantly reduced the stability of the cup, while 1 mm of offset eccentricity produced an even greater impact. Résumé Les modes les plus fréquents d'échecs des prothèses sans ciment sont le descellement de la cupule acétabulaire. Ce descellement est souvent en relation avec une stabilité initiale insuffisante. La cupule hémisphérique avec revêtement mis en place en press-fit avec vis additionnelles est un des modes opératoires les plus utilisés. De nombreuses études ont montré que l'utilisation de vis permettait de sécuriser la fixation. Pour cette étude, nous avons fixé des cupules hémisphériques dans un bloc d'os artificiel avec 0 à trois vis. Les effets de trois types de vissage ont permis d'évaluer la stabilité initiale de la cupule. Cette étude expérimentale montre que plus les vis sont nombreuses, meilleure est la stabilité. Une fixation excentrique de la cupule à 15°, stabilisée par une à deux vis n'a pas de conséquences néfastes, cependant une excentricité de 25°diminue de façon significative la stabilité de la cupule, de même, en ce qui concerne l'offset avec excentration de 1 mm.

We examined the mechanical consequences of high partial transverse sacrectomy. Ten human cadaveric pelves were randomly assigned to three groups. In the Control Group, the sacrum was left entirely intact. In Group I, transverse partial sacrectomy was performed just caudal to the S1 neural foramina. In Group II, transverse partial sacrectomy was performed just cephalad to the S1 neural foramina. Each pelvis was mounted on a testing apparatus and loaded vertically at the L4/L5 disk space until failure occurred. The average resection of the sacroiliac joints was 16% in Group I, and 25% in Group II. The average load to failure was 3014 N in the Control Group, 2166 N in Group I, and 1045 N in Group II. The average stiffness was 353 N/mm in the Control Group, 222 N/mm in Group I, and 100 N/mm in Group II. All specimens failed because of fractures through the sacrum (mostly Denis Zone II) in the sagittal plane. Using the literature to predict normal forces at the lumbosacral junction, we suggest Group I pelves could withstand postoperative mobilization without fracture, whereas Group II would probably not. Reconstruction should therefore be considered when performing transverse partial sacrectomy above the S1 nerve root.