Jean-Claude Theis

Fat embolism and acute hypotension during vertebroplasty: an experimental study in sheep.

Study Design. An experimental study of cardiovascular complications that arise during vertebroplasty was conducted. Objective. To investigate the sequential occurrence of fat embolism and hypotension during vertebroplasty. Summary of Background Data. Vertebroplasty, the augmentation of vertebrae with polymethylmethacrylate, is a technique for treating osteoporotic compression fractures and achieving prophylactic stabilization of osteoporotic vertebral bodies at risk of fracture. However, there is concern that fat embolism and acute hypotension could occur as in a variety of other orthopedic procedures. Methods. In six sheep, 6 mL of polymethylmethacrylate was injected unilaterally into L1. Transesophageal echocardiography monitored the pulmonary artery for echodense particles. Heart rate, arterial and venous pressures, and blood gas values were recorded before and for 25 minutes after injection. The lungs were subjected to postmortem histologic evaluation and compared with lung specimens from two sheep that had not undergone vertebroplasty. Results. Injection of cement elicited a very rapid decrease in heart rate (within 2 ± 1 seconds) and a rapid increase in venous pressure (within 3 ± 1 seconds), which was followed by a fall in arterial pressure (within 5 ± 2 seconds) (phase 1). Thereafter, showers of echogenic material appeared (within 6 ± 1 seconds) and lasted for 138 ± 36 seconds. A second more severe fall in arterial pressure was observed beginning at 18 ± 2 seconds (phase 2). The injection resulted in an increase in partial pressure of carbon dioxide and a decrease in pH. The histology showed intravascular fat globules and bone marrow cells in lung tissue. Conclusions. The results suggest that immediately after cement injection, there was a reflex fall in heart rate and arterial pressure. The second fall in arterial pressure was a consequence of fat emboli passing through the heart and getting trapped in the lungs.

Identification of prognostic factors for chronicity in patients with low back pain: a review of screening instruments

Low back pain (LBP) is currently the most prevalent and costly musculoskeletal problem in modern societies. Screening instruments for the identification of prognostic factors in LBP may help to identify patients with an unfavourable outcome. In this systematic review screening instruments published between 1970 and 2007 were identified by a literature search. Nine different instruments were analysed and their different items grouped into ten structures. Finally, the predictive effectiveness of these structures was examined for the dependent variables including “work status“, “functional limitation”, and “pain“. The strongest predictors for “work status” were psychosocial and occupational structures, whereas for “functional limitation” and “pain” psychological structures were dominating. Psychological and occupational factors show a high reliability for the prognosis of patients with LBP. Screening instruments for the identification of prognostic factors in patients with LBP should include these factors as a minimum core set.RésuméLa lombalgie (LBP) est un problème important notamment sur le poste des dépenses dans nos sociétés modernes. Sur le plan évolutif, il est primordial de pouvoir dépister des facteurs pronostics négatifs de ces patients. entre 1970 et 2007, un certain nombre d’éléments permettant cette analyse ont été identifiés dans la littérature. Ces instruments d’analyse nous semblent importants de façon à déterminer la limitation fonctionnelle, les possibilités de travail et la douleur. l’élément de prévision le plus important pour la poursuite d’un emploi est psychosocial, de ce fait l’élément important pour apprécier le pronostic de limitation fonctionnelle ou de douleur est plutôt psychologique. les facteurs psychologiques et sociaux permettent de faire le pronostic des lombalgies, il s’agit d’un tronc commun des éléments de dépistage, devant inclure tous ces facteurs.

Nerve Root Sedimentation Sign : Evaluation of a New Radiological Sign in Lumbar Spinal Stenosis

Study Design. Retrospective case-referent study. Objective. To assess whether the new sedimentation sign discriminates between nonspecific low back pain (LBP) and symptomatic lumbar spinal stenosis (LSS). Summary of Background Data. In the diagnosis of LSS, radiologic findings do not always correlate with clinical symptoms, and additional diagnostic signs are needed. In patients without LSS, we observe the sedimentation of lumbar nerve roots to the dorsal part of the dural sac on supine magnetic resonance image scans. In patients with symptomatic and morphologic central LSS, this sedimentation is rarely seen. We named this phenomenon “sedimentation sign” and defined the absence of sedimenting nerve roots as positive sedimentation sign for the diagnosis of LSS. Methods. This study included 200 patients. Patients in the LSS group (n = 100) showed claudication with or without LBP and leg pain, a cross-sectional area <80 mm2, and a walking distance <200 m; patients in the LBP group (n = 100) had LBP, no leg pain, no claudication, a cross-sectional area of the dural sac >120 mm2, and a walking distance >1000 m. The frequency of a positive sedimentation sign was compared between the 2 groups, and intraobserver and interobserver reliability were assessed in a random subsample (n = 20). Results. A positive sedimentation sign was identified in 94 patients in the LSS group (94%; 95% confidence interval, 90%–99%) but none in the LBP group (0%; 95% confidence interval, 0%–4%). Reliability was kappa = 1.0 (intraobserver) and kappa = 0.93 (interobserver), respectively. There was no difference in the detection of the sign between segmental levels L1–L5 in the LSS group. Conclusion. A positive sedimentation sign exclusively and reliably occurs in patients with LSS, suggesting its usefulness in clinical practice. Future accuracy studies will address its sensitivity and specificity. If they confirm the signs high specificity, a positive sedimentation sign can rule in LSS, and, with a high sensitivity, a negative sedimentation sign can rule out LSS.

Pelvic Pseudotumor: An Unusual Presentation of an Extra-Articular Granuloma in a Well-Fixed Total Hip Arthroplasty

A 76-year-old woman developed a pelvic mass and abdominal pain 12 years after cementless total hip arthroplasty. The mass was a cystic granuloma that communicated with the hip joint via a soft tissue herniation under the inguinal ligament. There was no acetabular lysis or defects. The shell and femoral component were well fixed, the polyethylene was worn, and a liner exchange was undertaken. The cyst was debrided, and follow-up computed tomography demonstrated resolution of the granuloma and no recurrence of the cyst. Removal of the source of the particle wear debris via liner exchange or revision surgery combined with cyst debridement via a single incision is recommended.

Exercise therapy, manual therapy, or both, for osteoarthritis of the hip or knee: a factorial randomised controlled trial protocol

BackgroundNon-pharmacological, non-surgical interventions are recommended as the first line of treatment for osteoarthritis (OA) of the hip and knee. There is evidence that exercise therapy is effective for reducing pain and improving function in patients with knee OA, some evidence that exercise therapy is effective for hip OA, and early indications that manual therapy may be efficacious for hip and knee OA. There is little evidence as to which approach is more effective, if benefits endure, or if providing these therapies is cost-effective for the management of this disorder. The MOA Trial (Management of OsteoArthritis) aims to test the effectiveness of two physiotherapy interventions for improving disability and pain in adults with hip or knee OA in New Zealand. Specifically, our primary objectives are to investigate whether:1. Exercise therapy versus no exercise therapy improves disability at 12 months;2. Manual physiotherapy versus no manual therapy improves disability at 12 months;3. Providing physiotherapy programmes in addition to usual care is more cost-effective than usual care alone in the management of osteoarthritis at 24 months.MethodsThis is a 2 × 2 factorial randomised controlled trial. We plan to recruit 224 participants with hip or knee OA. Eligible participants will be randomly allocated to receive either: (a) a supervised multi-modal exercise therapy programme; (b) an individualised manual therapy programme; (c) both exercise therapy and manual therapy; or, (d) no trial physiotherapy. All participants will continue to receive usual medical care. The outcome assessors, orthopaedic surgeons, general medical practitioners, and statistician will be blind to group allocation until the statistical analysis is completed. The trial is funded by Health Research Council of New Zealand Project Grants (Project numbers 07/199, 07/200).DiscussionThe MOA Trial will be the first to investigate the effectiveness and cost-effectiveness of providing physiotherapy programmes of this kind, for the management of pain and disability in adults with hip or knee OA.Trial registrationAustralian New Zealand Clinical Trials Registry ref: ACTRN12608000130369.

The international spine registry SPINE TANGO: status quo and first results

With an official life time of over 5 years, Spine Tango can meanwhile be considered the first international spine registry. In this paper we present an overview of frequency statistics of Spine Tango for demonstrating the genesis of questionnaire development and the constantly increasing activity in the registry. Results from two exemplar studies serve for showing concepts of data analysis applied to a spine registry. Between 2002 and 2006, about 6,000 datasets were submitted by 25 centres. Descriptive analyses were performed for demographic, surgical and follow-up data of three generations of the Spine Tango surgery and follow-up forms. The two exemplar studies used multiple linear regression models to identify potential predictor variables for the occurrence of dura lesions in posterior spinal fusion, and to evaluate which covariates influenced the length of hospital stay. Over the study period there was a rise in median patient age from 52.3 to 58.6 years in the Spine Tango data pool and an increasing percentage of degenerative diseases as main pathology from 59.9 to 71.4%. Posterior decompression was the most frequent surgical measure. About one-third of all patients had documented follow-ups. The complication rate remained below 10%. The exemplar studies identified ‘‘centre of intervention’’ and ‘‘number of segments of fusion’’ as predictors of the occurrence of dura lesions in posterior spinal fusion surgery. Length of hospital stay among patients with posterior fusion was significantly influenced by ‘‘centre of intervention’’, ‘‘surgeon credentials’’, ‘‘number of segments of fusion’’, ‘‘age group’’ and ‘‘sex’’. Data analysis from Spine Tango is possible but complicated by the incompatibility of questionnaire generations 1 and 2 with the more recent generation 3. Although descriptive and also analytic studies at evidence level 2++ can be performed, findings cannot yet be generalised to any specific country or patient population. Current limitations of Spine Tango include the low number and short duration of follow-ups and the lack of sufficiently detailed patient data on subgroup levels. Although the number of participants is steadily growing, no country is yet represented with a sufficient number of hospitals. Nevertheless, the benefits of the project for the whole spine community become increasingly visible.

Age at hip or knee joint replacement surgery predicts likelihood of revision surgery

We compared revision and mortality rates of 4668 patients undergoing primary total hip and knee replacement between 1989 and 2007 at a University Hospital in New Zealand. The mean age at the time of surgery was 69 years (16 to 100). A total of 1175 patients (25%) had died at follow-up at a mean of ten years post-operatively. The mean age of those who died within ten years of surgery was 74.4 years (29 to 97) at time of surgery. No change in comorbidity score or age of the patients receiving joint replacement was noted during the study period. No association of revision or death could be proven with higher comorbidity scoring, grade of surgeon, or patient gender. We found that patients younger than 50 years at the time of surgery have a greater chance of requiring a revision than of dying, those around 58 years of age have a 50:50 chance of needing a revision, and in those older than 62 years the prosthesis will normally outlast the patient. Patients over 77 years old have a greater than 90% chance of dying than requiring a revision whereas those around 47 years are on average twice as likely to require a revision than die. This information can be used to rationalise the need for long-term surveillance and during the informed consent process.

Pressurization of vertebral bodies during vertebroplasty causes cardiovascular complications: an experimental study in sheep.

Study Design. An experimental study of cardiovascular complications arising during vertebroplasty (VP) of multiple levels in sheep. Objectives. To investigate the effect of pressurizing vertebral bodies during VP using different materials in the development of fat embolism (FE) and any associated cardiovascular changes. Summary of Background Data. Polymethylmethacrylate (PMMA) is the material of choice for VP. However, PMMA has several disadvantages, such as toxicity, exothermic curing, uncertain long-term biomechanical effects, and biocompatibility. Alternative materials are being developed for VP; however, there is the concern that an increase in intraosseous pressure and displacement of bone marrow contents could lead to FE and hypotension during VP regardless of what type of materials is used. Methods. In 20 sheep, four vertebral bodies were augmented either with PMMA or bone wax. Heart rate; arterial, central venous, and pulmonary artery pressure; cardiac output; and blood gas values were recorded. Postmortem the lungs were subjected to histologic evaluation. Results. The consecutive augmentation of four vertebral bodies with PMMA induced a cumulative FE that gradually deteriorated baseline mean arterial blood pressure (MABP) and blood gas values. The augmentation with bone wax resulted in similar cardiovascular changes and amount of intravascular fat in the lungs. Conclusion. There are potential cardiovascular complications during VP of multiple levels regardless of the augmentation material used. The deteriorating baseline MABP during VP is associated with the pressurization of the vertebral bodies rather than with the use of polymethylmethacrylate.

Correction of Complex Lower Limb Deformities by the Ilizarov Technique: An Audit of Complications

This is an audit of complications resulting from correction of complex lower limb deformities by the Ilizarov technique. 33 patients (40 bone segments) were reviewed and divided into 4 groups according to the type of surgery carried out: limb lengthening and/or correction of deformity, bone or joint stabilisation, treatment of nonunion or bone defect, angular and/or rotation correction. Most minor complications were fixator specific. Pin tract infections were almost universal but responded well to oral antibiotics and rarely resulted in osteomyelitis. Major complications were procedure specific and more common in those patients who underwent leg lengthening, treatment for nonunion and bone transport. There was also a high incidence of nerve injury as a result of acute angular deformity correction. Despite the high complication rate the Ilizarov technique remains an effective tool for complex lower limb reconstruction surgery.

Degradation of hydroxyapatite coating on a well-functioning femoral component.

We carried out a histological study of a proximally hydroxyapatite (HA)-coated femoral component, retrieved after 9.5 years of good function. The HA coating had completely degraded. Bone was in direct contact with the titanium surface in all the areas which had been coated, with no interposing fibrous tissue. There were no signs of particles, third-body wear, adverse tissue reactions or osteolysis. Bone remodelling was evident by the presence of resorption lacunae; tetracycline labelling showed bone laid down six years after implantation. The loss of the HA-coating had no negative effect on the osseo-integration of the stem. We conclude that the HA coating contributes to the fixation of the implant and that its degradation does not adversely affect the long-term fixation.