Arthrodesis after failed total ankle replacement.

We present a series of 16 patients treated between 1993 and 2006 who had a failed total ankle replacement converted to an arthrodesis using bone grafting with internal fixation. We used tricortical autograft from the iliac crest to preserve the height of the ankle, the malleoli and the subtalar joint. A successful arthrodesis was achieved at a mean of three months (1.5 to 4.5) in all patients except one, with rheumatoid arthritis and severe bone loss, who developed a nonunion and required further fixation with an intramedullary nail at one year after surgery, before obtaining satisfactory fusion. The post-operative American Orthopaedic Foot and Ankle Society score improved to a mean of 70 (41 to 87) with good patient satisfaction. From this series and an extensive review of the literature we have found that rates of fusion after failed total ankle replacement in patients with degenerative arthritis are high. We recommend our method of arthrodesis in this group of patients. A higher rate of nonunion is associated with rheumatoid arthritis which should be treated differently.

Relationship between locking-bolt torque and load pre-tension in the Ilizarov frame.

The wire-bolt interface in an Ilizarov frame has been mechanically tested. The optimal torque to be applied to the frame locking-bolts during physiological loading has been defined. The set-up configuration was as is used clinically except a copper tube was used to simulate bone. The force-displacement curves of the Ilizarov wires are not altered by locking-bolt torque. The force in the bone model at which pre-tension is lost increases as the locking-bolts are tightened to 14 Nm torque, but decreases if torque exceeds 14 Nm. Thus, 14 Nm is the optimal locking-bolt torque in frame. The relationship between pre-tension versus load for different locking-bolt torques arises because at low and high clamping torques poor wire holding and plastic deformation respectively occur. Wire damage was seen under light and electron microscopy. Clinically, over or under-tightening locking-bolts will cause loss of pre-tension, reduction in frame stiffness and excessive movement at the fracture site, which may be associated with delayed union.

Extensive spinal epidural abscess associated with an unremarkable recovery.

Spinal epidural abscess is a rare complication of epidural catheter insertion, with an incidence reported to be as low as 0.02%, but with a high morbidity and mortality. This reflects the difficulty in diagnosis of the condition, as early symptoms and signs are usually non-specific with late neurological manifestations. We report a case of spinal epidural abscess in a diabetic patient who underwent splenectomy and distal pancreatectomy. Early investigation with magnetic resonance imaging was effective in demonstrating an extensive epidural abscess involving the thoracic spine, with extension to the base of the skull and associated cord compression. Extensive multilevel laminectomies with thorough irrigation and washout of the epidural space were successful in treating this patient and preventing the development of permanent neurological sequelae.

The role of rehydration in the prevention of fat embolism syndrome.

We encountered three cases of young sportsmen developing fat embolism syndrome (FES) after sustaining isolated tibial shaft fractures whilst playing football. All fractures were treated with intra-medullary nails and all three patients were kept nil-by-mouth pre-operatively without intravenous fluids. Correction of shock is often quoted as an important factor in the prevention of FES. However, animal studies have shown that dehydration, as opposed to hypovolaemia, may also be of great importance. We therefore examined the specific gravity of the urine of 20 patients with musculoskeletal injuries sustained during sport. The mean urinary specific gravity was significantly higher than that of a control group of 10 members of staff. We emphasise the importance of adequate pre-operative rehydration, especially if injuries were sustained during heavy exercise, as this may reduce the risk of developing FES.