Surgical management of persistent post-traumatic trans-tentorial brain hernia.

INTRODUCTION: Temporal engagement may persist after etiologic surgical treatment of acute subdural hematoma (ASH) without clinical improvement despite normalized intracranial pressure (ICP). The aim of this study was to assess the feasibility of secondary direct temporal lobe disengagement (DTLD) after surgery for supratentorial ASH and to evaluate clinical outcome. MATERIALS AND METHODS: This was a retrospective analysis of 4 patients undergoing secondary DTLD. Patient data were recorded at admission, pre- and postoperatively and at 6months' follow-up (FU): age, gender, Rotterdam score, Glasgow Coma Scale (GCS), neurological deficits, oculomotor nerve palsy (ONP), ICP, midline shift, complications and Extended Glasgow Outcome Scale (GOS-E). RESULTS: At postoperative evaluation 48h after DTLD, we observed a significant improvement in GCS score (initial 6±3, preoperative 7±3, postoperative 14±1; P=0.02), midline shift (initial 16±3mm, preoperative 13±5mm, postoperative 9±2mm; P=0.049) and ONP (P=0.01). In all cases, early postoperative imaging documented visualization of a patent ipsilateral peri-mesencephalic cistern. At 6-month FU, GOS-E showed 75% good recovery and 25% disability. Complete ONP recovery was observed in 75% of patients (P=0.01). Neurological deficits were present at FU in 25% of patients. No surgery-related complications or mortality were recorded. CONCLUSIONS: In traumatic brain injury, secondary DTLD may allow simple, effective and safe management of trans-tentorial uncal herniation, avoiding more challenging procedures. Clinical results are promising, as this technique seems to favorably influence neurological outcome in this selected subgroup of patients with persistent clinical and radiological signs of temporal engagement after etiological treatment with normal ICP values.

Unacceptable biodegradation of polyethylene in vivo.

The chemical characterization of 19 retrieved ultra-high-molecular-weight polyethylene tibial plateaux, six new ones and one raw bar was performed by means of infrared spectroscopy. The surface and bulk oxidation and biodegradation indexes were calculated. The raw bar has a measurable oxidation, which increases on the bulk and on the surfaces of the new plateaux. In the retrieved plateaux, the average oxidation index increases further both on the bulk and on the surfaces; the worse values were present on the worn area. Similar results were found for the biodegradation index. The data show that the biotic in vivo degradation is promoted by the oxidation present on the new plateaux and that it occurs through a different mechanism, abiotic thermal-, photo-, gamma-radiation oxidation, evaluated by the oxidation index.

In vivo UHMWPE biodegradation of retrieved prosthesis.

Sixty-two ultra high molecular weight polyethylene prosthetic components (PEs) (31 tibial plateaux and 31 cups), sterilised by gamma rays or ethylene oxide (EtO), were retrieved after 1-12 years depending on different medical reasons and were studied by FTIR spectroscopy with derivatisation of oxidised species. Esters, acids and hydroperoxides were found under the surface of the EtO sterilised PEs up to 2 mm depth. The behaviour of gamma ray sterilised PEs is more complex due to the oxidation following the sterilisation process. Ester and acid formation might arise from the diffusion of components of synovial liquid or from the oxidation process, whereas hydroperoxide formation is thought to be due to the oxidation. Abrasion and delamination process is discussed considering the topological distribution of degradation products.

Oxidation in orthopaedic UHMWPE sterilized by gamma-radiation and ethylene oxide.

Ten new polyethylene prosthetic components (PEs), ethylene oxide (EtO)- and gamma-sterilized, were studied by means of infrared (IR) analysis in order to evaluate oxidation. Using attenuate total reflection infrared spectroscopy the authors demonstrate that all samples show surface oxidation, formed during processing and shaping, related to mechano-degradation. By means of Fourier transform infrared (FTIR) microscopy and derivatization techniques, the EtO-sterilized PEs present different behaviour in comparison to the gamma-radiated. The former show low levels of depth oxidation that could be related to the degradation which occurred during preparation of slices for IR analysis. The gamma-sterilized PEs show higher oxidation levels, variable from sample to sample, on the surface and in the bulk. The authors demonstrate that oxidation is described both by carbonyl species distribution and by hydroperoxide concentration. The hydroperoxides could be responsible for oxidative PEs ageing in in vivo service. The different oxidation levels and distribution could depend on the conditions of gamma-sterilization, in particular on the rate of the dose absorbed, not previously reported for ready-to-implant PEs. Chain scission of gamma-radiated UHMWPE, estimated by IR analysis, results in reduction of molecular weight and consequently in less abrasive resistance. The scheme of UHMWPE oxidation due to gamma-sterilization demonstrates the inhomogeneous distribution of reactive species in PEs responsible for the unpredictable performance in vivo.

Biocompatibility and osteogenetic characteristics of new biocompatible glasses.

A fibre-shaped glass with qualities of biocompatibility and biodegradation could be promising for reconstructive bone surgery in orthopaedics and neurosurgery. New highly biocompatible glasses, originally made by the Italian Group of Study on Biocompatible Glass, are obtained both in cylinder and fibre shapes due to their original chemical composition (Glassfiber). This is the only glass which is also available as a continuous filament. Hydrolytic in vitro and in vivo tests demonstrate that these glasses present both good biocompatibility and adjustable biodegradation in relation to their chemical composition. The advantages of bioactive glass also being available as a continuous filament are suggested.

Spinal fusion in degenerative disc disease.

Low back pain caused by degenerative disc disease is of such intensity in a low percentage of cases that surgery is indicated. Surgery must not only stabilize, but it must above all correct the deformity, recovering the disc space. Among all of the methods available circumferential fusion with a double combined approach, that is, anterior and posterior, is held to be the most effective.

Stenosis of the nerve root canal caused by disc resorption.

Stenosis of the nerve root canal caused by isolated resorption of a lumbar disc is a frequently observed pathology, but one about which the orthopaedist still knows relatively little. Henry Crock was the first to reveal its principal pathogenetic factor, disc resorption, and to accurately describe the syndrome and its surgical treatment. A total of 22 patients operated according to Henry Crock's indications and followed-up after 2 years were reviewed. In 20 cases decompression alone was performed, while in 2 cases anterior fusion and MOSS instrumentation were associated. Of the 22 patients submitted to decompression 17 revealed complete regression of pain. Three cases failed: 1 patient had previously been treated with chymopapain, while 3 are awaiting anterior fusion to treat persistent lumbar pain. Follow-up is not sufficient for the two patients submitted to anterior fusion.

The surgical treatment of thoracolumbar metastases.

Between 1990 and June 1995 a total of 41 patients affected with vertebral metastases caused by neoplasm with different histotypes were treated at the Ist Clinical Orthopaedics and Traumatology Division at the University of Turin. A method proposed by J. Harms was used, nearly always involving a combined anterior and posterior surgical approach. At the Division of Orthopaedics of the Ospedale Maria Adelaide in Turin between 1993 and June 1995 a total of 16 patients affected with vertebral metastases caused by neoplasms of different histotypes were treated. Decompression and posterior stabilization alone using Diapason instrumentation was prevalently performed. Patients with a life expectancy of at least 6 months were treated. Follow-up was obtained by interviewing the patients over the phone during August of 1995. In the cases at the Ist Division of Orthopaedics the number of levels that were instrumented were on the average 2.5, at follow-up 83% of the patients stated that they were satisfied, while only 7.4% were unsatisfied. In the second series (Ospedale Maria Adelaide) the number of levels instrumented was on the average 8, at follow-up 62.5% of the patients said that they were satisfied, while 31.8% said that they were unsatisfied.

The biological reaction to polyethylene wear debris can be related with oxidation of the UHMWPE cups.

BACKGROUND: Oxidised UHMWPE due to gamma irradiation in air has a greater susceptibility to wear than non-oxidised UHMWPE (ethylene oxide, EtO). AIM: To evaluate, the biological reaction of loose implants with oxidised and non-oxidised PE components. MATERIALS AND METHODS: Ten loose PE cups sterilised by EtO (group 1) and 13 sterilised by gamma irradiation in air (group 2) were studied. PE wear and oxidation were related to biological reaction. RESULTS: Group 1: PE cups had low wear score and no oxidation. In the oldest implants, a few PE particles and macrophages were observed in the interface membrane. Group 2: PE inserts had medium-to-high PE wear score and variable oxidation. In the interface membrane, the number and total area of PE particles were high and variable; giant cells were more numerous than macrophages. CONCLUSION: Junctional tissues around loose oxidised PE components contain more PE debris and giant cells than membranes around PE components that are not oxidised.