Purpose of the study: The aim of this work was to study the functional and radiological results as well as any complications obtained after minimally invasive treatment of bimalleolar fractures.

Material and methods: The series included 100 fractures in 100 patients who underwent surgery between 1998 and 2000: 52 men and 48 women, mean age 47.1 years (range 17–96 years). According to the AO classification, the fractures were A:18, B:62, C:20. Osteosynthesis of the lateral malleolus was achieved with a Rush nail in 95 cases and with a K-wire in six. Closed osteosynthe-sis was achieved in 67 cases, an open procedure being used for 33 cases. Osteosynthesis was performed on the medial malleolus in 73 patients, 65 with a 3.5-mm screw, a K-wire for five, and a tutor-wire in two, all during an open procedure. The functional outcome was assessed at last follow-up using the Olerund and MOlander and the AOFAS scores.

Results: Mean follow-up was thirteen months (range 3–54 months). All fractures healed at mean eight weeks (range 6–24 weeks). At last follow-up, 90 ankles were radiographically anatomic. Mean function scores were: Olerund and Molander 73.5/90; AOFAS 85.8/100. Clinical outcome (Olerund and Molander) was excellent or good in 86 patients, poor in 12 and very poor in two. According to the AOFAS score, clinical outcome was excellent or good in 90 patients, poor in 9 and very poor in one. Considered by gender and type of reduction of the lateral malleolus, there was no difference in the distribution of the clinical outcome. There was however a strong correlation between the quality of the anatomic result and the functional outcome since poor anatomic results gave poor functional results in 80% of cases. The type of anatomic fracture had a certain importance since excellent and good results were obtained for type A fractures (94%) and type C fractures (90%) but 70% of the poor results were observed in type B fractures. There were few complications: two superficial infections, four cases of reflex dystrophy, and one thromboembolic event.

Conclusion: Compared with other operative techniques, the advantages of this method are basically linked to the ability to respond to all the different forms of bimalleo-lar fracture, irrespective of the anatomic type. The operative protocol is well established. The procedure is easy to perform and rapid and provides excellent results.

Purpose: Isolated paralysis of the great toe long extensor is a rare complication of leg fractures. In certain patients, an erroneous diagnosis of compartment syndrome or muscle incarceration may be made.

Material and methods: We dissected ten fresh cadavers.

Results: The great toe long extensor was innervated by a branch of the deep fibular nerve which arose 15 cm from the talocrural joint space and directly in contact with the periosteum of the tibial shaft. In this localisation, the branch can be directly sectioned during trauma, reduction, or reaming.

Discussion: We had one patient aged 30 years with a fracture of the mid third of the leg who was treated by centromedullar nailing. Postoperatively, this patient developed isolated paralysis of the great toe long extensor. The isolated neurogenic origin of this paralysis was confirmed by electromyography.

Conclusion: This case is illustrative of direct injury of the great toe long extensor innervation, a cause which to our knowledge has not been previously described.

Introduction: Enlarging cystic cavitations (syrinxes) form within the spinal cord in up to 28% of spinal cord injured patients. These post-traumatic syrinxes can cause neurological deterioration, and treatment results remain poor. Syrinxes are often found adjacent to regions of arachnoiditis.

The understanding of biological systems is increasingly dependent on modelling and simulations. Numerical simulation is not intended to replace in vivo experimental studies, but to enhance the understanding of biological systems. This study tests the hypothesis that pressure pulses in the SAS are high adjacent to areas of arachnoiditis and investigates the validity of a numerical model by comparison with in vivo experimental findings.

Methods: Experimental Model: Post-traumatic syringomyelia was induced in eight sheep by injection of kaolin into the subarachnoid space (SAS), and excitotoxic amino acid into the spinal cord of the upper thoracic spine. Cerebrospinal fluid (CSF) pressure studies were undertaken at either 3 or 6 weeks. Fibre-optic monitors were used to measure the pressure in the SAS 1 cm rostral and 1 cm caudal to the induced arachnoiditis.

Numerical Model: An axisymmetric fluid-structure interaction model was developed to represent the spinal cord and SAS under normal physiological conditions and in the presence of arachnoiditis. Arachnoiditis was modeled as a porous obstruction in the SAS.

Results: In both models the SAS pressure rostral to the arachnoiditis was found to be higher than the caudal SAS pressure. There was no statistically significant difference between the sheep at 3 and 6 weeks. Under normal conditions, both experimentally and in the numerical model, the pressure drop along the SAS was negligible. In the presence of arachnoiditis, the pressure drop across the arachnoiditis in the experimental model was 1.6 mmHg, whereas the numerical model predicted a pressure difference of 1.3 mmHg.

Discussion: The numerical model accurately predicts CSF pressures in the animal model under both normal and abnormal conditions, allowing predictions to be made to within 20% accuracy. The local increases in SAS CSF pressure demonstrated may act to increase fluid flow through perivascular spaces and be implicated in syrinx formation and enlargement.

Purpose: Compartment syndrome of the leg is an exceptional (0.8% of leg fractures) but serious complication with a risk of muscle necrosis. The purpose of this work was to propose an original therapeutic approach to compartment syndromes that have progressed to the stage of muscle necrosis.

Material and method: Between November 1999 and January 2001, we treated eleven patients with acute compartment syndrome of the leg. There were ten men and one women, mean age 38 year (range 19–70). The causal mechanism was fracture of the two leg bones in nine patients (during the study period, 129 leg fractures were managed in the unit). For two patients the causal mechanism was prolonged compression. The compartment syndrome was present at admission in seven patients and developed after nailing in two. Emergency aponeurotomy was performed in all cases.

Results: Mean follow-up was six months, range 3 – 26 months. Outcome was favourable in six patients and the aponeurotomy was closed between day 5 and 10 (mean day 7), associated with a skin graft in some patients. Muscle necrosis developed in four patients. These patients were treated by wide muscle excision and immediate wound closure with aspiration drainage, followed by a prolonged adapted antibiotic regimen. Complete healing with total regression of the infectious syndrome was achieved. Partial recovery of sensory and motor function was obtained in all cases. One patient required a cross-leg flap for cover after infectious necrosis. One other patient aged 57 years died a few hours after aponeurotomy due to cardiac failure of undetermined origin.

Discussion: Compartment syndrome is a recognised surgical emergency. All authors recommend emergency aponeurotomy. There is no standard treatment after progression to muscle necrosis.

Conclusion: Muscle necrosis is not uncommon despite aponeurotomy (4 out of 11 patients in our series). In case of muscle necrosis, we propose wide excision and immediate wound closure associated with adapted antibiotics. Despite the muscle excision, partial recovery of sensorial and motor function of the foot was achieved several months after the initial treatment.

Introduction: Modern imaging techniques have demonstrated that up to 28% of patients with spinal cord injury develop syringomyelia. Cyst formation and enlargement are thought to be related to abnormalities of cerebrospinal fluid hydrodynamics, however the exact mechanism and route of entry into the spinal cord remain incompletely understood. Previous work in rats has demonstrated that experimental post-traumatic syrinxes occur more reliably and are larger when the excitotoxic injury is combined with arachnoiditis produced by subarachnoid kaolin injection. A sheep model of post-traumatic syringomyelia (P.T.S.) has been characterised and studies of cerebrospinal fluid dynamics are currently being undertaken. The aim of this study was to assess the effect of focal subarachnoid space blockage on spinal fluid pressures and flow.

Methods: Arachnoiditis was induced in 5 sheep by injection of 1.5 mls of kaolin in the subarachnoid space (SAS) of upper thoracic spinal cord. The animals were left for 6–8 weeks before C.S.F. studies were undertaken. In another 5 sheep, a ligature was passed around the spinal cord to simulate an acute blockage of the subarachnoid space. Fluid-coupled monitors were used to measure blood pressure, central venous pressure and subarachnoid pressure (1cm rostral and 1 cm caudal to the arachnoiditis or ligature). Fiberoptic monitors were used to measure intracranial pressure. In the ligature group, subarachnoid pressures were also measured prior to tying the ligature to obliterate the SAS and served as baseline control pressures. The effects of Valsalva and Queckenstedt manoeuvres on SAS pressures were examined in both groups.

CSF flow was studied at 0 and 10 minutes after injection of the CSF tracer horseradish peroxidase (HRP). Vibratome sections of the spinal cord were processed using tetramethylbenzidine and sections examined under light microscopy.

Results: The mean SAS pressure rostral to the arachnoiditis was found to be greater than the mean caudal SAS pressure by 1.7 mmHg. In the ligature group, the difference was 0.9 mmHg, being higher in the caudal SAS. Queckenstedt manoeuvre exaggerated this difference to 3 mmHg in the Kaolin group and 4 mmHg in the ligature group. The effect of Valsalva was much less marked in both groups.

Perivascular spaces were enlarged in most cases of arachnoiditis and HRP was seen to stain these spaces and the central canal within 10 minutes.

Discussion: Post-traumatic syrinxes are usually juxtaposed to the injury site with 80% occurring rostral, 4% caudal and 15%in both directions. The finding of a higher subarachnoid pressure rostral to the injury site may help explain this phenomenon. We hypothesize that a reduction of compliance in subarachnoid space increases the pulse pressure and hence increases perivascular flow of C.S.F. contributing to the formation and enlargement of PTS. We are currently investigating this hypothesis by measuring subarachnoid space compliance directly in the sheep model of arachnoiditis described above.

INTRODUCTION: Modern imaging techniques have demonstrated that up to 28% of patients with spinal cord injury develop syringomyelia. Cyst formation and enlargement are thought to be related to abnormalities of cerebrospinal fluid hydrodynamics, however the exact mechanism and route of entry into the spinal cord remain incompletely understood. Previous work in rats has demonstrated that experimental post-traumatic syrinxes occur more reliably and are larger when the excitotoxic injury is combined with arachnoiditis produced by subarachnoid kaolin injection. A sheep model of post-traumatic syringomyelia (P.T.S.) has been characterised and studies of cerebrospinal fluid dynamics are currently being undertaken. The aim of this study was to assess the effect of focal subarachnoid space blockage on spinal fluid pressures and flow.

METHODS: Arachnoiditis was induced in five sheep by injection of 1.5 mls of kaolin in the subarachnoid space (SAS) of upper thoracic spinal cord. The animals were left for 6–8 weeks before C.S.F. studies were undertaken. In another five sheep, a ligature was passed around the spinal cord to simulate an acute blockage of the subarachnoid space. Fluid-coupled monitors were used to measure blood pressure, central venous pressure and subarachnoid pressure (1 cm rostral and 1 cm caudal to the arachnoiditis or ligature). Fiberoptic monitors were used to measure intracranial pressure. In the ligature group, subarachnoid pressures were also measured prior to tying the ligature to obliterate the SAS and served as baseline control pressures. The effects of Valsalva and Queckenstedt manoeuvres on SAS pressures were examined in both groups.

CSF flow was studied at 0 and 10 minutes after injection of the CSF tracer horseradish peroxidase (HRP). Vibratome sections of the spinal cord were processed using tetramethylbenzidine and sections examined under light microscopy.

RESULTS: The mean SAS pressure rostral to the arachnoiditis was found to be greater than the mean caudal SAS pressure by 1.7 mmHg. In the ligature group, the difference was 0.9 mmHg, being higher in the caudal SAS. Queckenstedt manoeuvre exaggerated this difference to 3 mmHg in the Kaolin group and 4 mmHg in the ligature group. The effect of Valsalva was much less marked in both groups.

Perivascular spaces were enlarged in most cases of arachnoiditis and HRP was seen to stain these spaces and the central canal within 10 minutes.

DISCUSSION: Post-traumatic syrinxes are usually juxtaposed to the injury site with 80% occurring rostral, 4% caudal and 15% in both directions. The finding of a higher subarachnoid pressure rostral to the injury site may help explain this phenomenon. We hypothesise that a reduction of compliance in subarachnoid space increases the pulse pressure and hence increases peri-vascular flow of C.S.F. contributing to the formation and enlargement of PTS. We are currently investigating this hypothesis by measuring subarachnoid space compliance directly in the sheep model of arachnoiditis described above.