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Synovial chondromatosis is an uncommon lesion, characterised by cartilaginous and osseous metaplasia of the joint synovium. It usually involves a large joint and rarely occurs in the hand. A case of tenosynovial chondromatosis of the third finger is reported.

We have carried out an experimental investigation of lesions of the intervertebral disc produced by flexion, lateral bending and rotational forces in an attempt to produce disc herniations. Adult Wistar rats were divided into 4 groups: control and posterior, lateral and rotational herniation. There were 10 rats in each group. The tail between the 5th and 8th vertebral segments was used. A Kirschner wire was inserted into each of 2 adjacent vertebrae and the movement produced had an apex which was anterior or lateral depending on the group involved. Variables such as rupture of the annulus, the cellularity of the nucleus pulposus and the site of the lesion in the disc were studied histologically. The height of the disc, the protrusion, the thickness, and the surfaces of the annulus fibrosus and the nucleus pulposus were measured. In every case we found a nuclear displacement which did not become a protrusion. The surface parameters and the cellularity of the nucleus pulposus are most useful indicators and should be included in any study examining the disc after the injection of substances for treatment.

We have carried out a biomechanical study of the forces acting on the Grosse-Kempf intramedullary nail to determine those which most affect its structure. We have used finite element analysis to assess the distribution of compression, flexion and torsion forces. The qualitative and quantitative distribution of the tension on the surface of the nail has been observed. We have shown that the torsional force is most important and it is exerted in the posterior part of the nail where there is a change from the unslotted to the slotted section.

The adherence of Staphylococcus aureus to biomaterials used in orthopaedic surgery (polymethylmethacrylate, fresh bone, steel and titanium alloys) and to glass was studied in vitro at 1, 2, 6, 24 and 48 h of incubation. Nonslime-producing strains (72, 80 and 510) and slime-producing variants of these strains were used. An automated and fast method of ATP-bioluminiscence was applied to determine bacterial viability. The lowest adherence corresponded to polymethylmethacrylate and bone, and the highest to metals. Significant adherence was detected in all cases after 6 h and was strain dependent, being lowest for strain 72. In most cases, adherence of nonslime-producing variants was not significant compared with controls, and slime-producing were more adherent than nonslime-producing variants. These differences were maximal at 6 h or 48 h, depending on the strain and the material. The findings suggest that the appearance of slime-producing cells within a given nonslime-producing bacterial population may jeopardise postoperative immune systems and antibiotic efficacy as a consequence of biofilm formation on implants and prostheses.

A retrospective review of complications with the gamma nail has been carried out in 152 patients with stable and unstable pertrochanteric fractures. Operative complications occurred in 10 patients. Screws penetrated the femoral neck in 3, immediate varus was associated with a short screw in 2, diaphyseal fractures occurred at the site of the distal screws in 3 and comminuted femoral fractures in 2. Fifteen patients (10.5%) died in hospital. At follow up, pseudarthrosis was present in 2 cases and fractures of the femoral shaft in 4. The incidence of complications could be reduced by using of shorter nails, less valgus angulation and by not introducing distal screws unless essential.

Although total knee arthroplasty is a valuable surgical technique, complications and problems do occur. Associated stress fracture of the femoral neck is relatively rare and we have only found eleven relevant reports. In this paper we present a case of bilateral total knee arthroplasty where three months after the second replacement, and without significant injury, the patient suffered a femoral neck fracture in the limb which had received the first new knee joint.