PubMed Health⌕ Search

Biomedical subjects

M J Parker

Publications and source records attributed to M J Parker.

At least 19 recordsLinked to original sources
PubMed2002

Surgical approaches for inserting hemiarthroplasty of the hip.

BACKGROUND: The operation of insertion of a hemiarthroplasty to the hip refers to replacement of the femoral head with a prosthesis, whilst retaining the natural acetabulum and acetabular cartilage. The main surgical approaches to the hip for insertion of the prosthesis can be broadly categorised as either 'anterior' via the anterior joint capsule, or 'posterior' through the posterior joint capsule. OBJECTIVES: To evaluate, based on evidence from randomised controlled trials, the effects of different surgical approaches for the insertion of a hemiarthroplasty to the hip has on clinical outcomes. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register (up to February 2002). Articles of all languages were considered. SELECTION CRITERIA: All randomised controlled trials comparing insertion of a hemiarthroplasty by different surgical approaches. DATA COLLECTION AND ANALYSIS: Both reviewers independently assessed trial quality, using a 10 item scale, and extracted data. Wherever appropriate and possible, the data are presented graphically. MAIN RESULTS: One randomised trial was identified involving 114 patients. The trial had poor methodology (particularly in susceptibility to selection bias), inadequate follow-up of patients who withdrew, and there was limited reporting of results. Medical complications and mortality from six months to two years appeared greater in the posterior group; this difference in mortality, within the structure of the poor methodology, was statistically significant. No other differences were claimed to be significant. REVIEWER'S CONCLUSIONS: There is currently insufficient evidence from randomised trials to determine the optimum surgical approach for insertion of a hemiarthroplasty to the hip.

Arthroplasty, Replacement, Hip↗
PubMed2002

Austin-Moore hemiarthroplasty for failed osteosynthesis of intracapsular proximal femoral fractures.

We studied the outcome of 100 uncemented Austin-Moore hemiarthroplasties used as a revision procedure for failed osteosynthesis of intracapsular femoral fractures. This group was compared with 730 patients in whom an uncemented Austin-Moore prosthesis had been used as the primary treatment for an intracapsular femoral fracture. The results indicate that the study group had more pain at 1-year post-fracture. There were also significantly more revision procedures in those who had the arthroplasty performed as a salvage procedure. In general, the results of uncemented Austin-Moore hemiarthroplasty used as a revision procedure for failed osteosynthesis are inferior to that for primary hemiarthroplasty. We would advocate that for any case in which there are signs of acetabular damage a total hip replacement might be a better procedure. For the remainder, an alternative arthroplasty should be considered with an uncemented Austin-Moore prosthesis reserved for only the very frail.

Aged↗
PubMed2002

Portal vein thrombosis causing neonatal cerebral infarction.

Neonatal cerebral infarction often occurs in the absence of known risk factors. Two such cases are described in which portal vein thrombosis was documented during two dimensional echocardiography. In both cases, infarcts were consistent with embolic events. A novel mechanism is proposed, which may explain some cases of "idiopathic" neonatal cerebral infarction.

Adult↗
PubMed2002

Hemiarthroplasty versus internal fixation for displaced intracapsular hip fractures in the elderly. A randomised trial of 455 patients.

A total of 455 patients aged over 70 years with a displaced intracapsular fracture of the proximal femur was randomised to be treated either by hemiarthroplasty or internal fixation. The preoperative characteristics of the patients in both groups were similar. Internal fixation has a shorter length of anaesthesia (36 minutes versus 57 minutes, p < 0.0001), lower operative blood loss (28 ml versus 177 ml, p < 0.0001) and lower transfusion requirements (0.04 units versus 0.39 units, p < 0.0001). In the internal fixation group 90 patients required 111 additional surgical procedures while only 15 additional operations on the hip were needed in 12 patients in the arthroplasty group. There was no statistically significant difference in mortality between the groups at one year (61/226 versus 63/229, p = 0.91), but there was a tendency for an improved survival in the older less mobile patients treated by internal fixation. For the survivors assessed at one, two and three years from injury there were no differences with regard to the outcome for pain and mobility. Limb shortening was more common after internal fixation (7.0 mm versus 3.6 mm, p = 0.004). We recommend that displaced intracapsular fractures in the elderly should generally be treated by arthroplasty but that internal fixation may be appropriate for those who are very frail.

Aged↗
PubMed2002

Internal fixation of intracapsular fractures.

The main indications for internal fixation of intracapsular fractures are undisplaced and minimally displaced fractures and displaced intracapsular fractures in those aged less than about 70 years. For displaced fractures, closed reduction is to be preferred to open reduction. Numerous different implants may have to be used; with current practice favouring two or three parallel cannulated cancellous screws. These may be inserted either percutaneously or with minimal surgical exposure. Attention to surgical details of fracture reduction and implant positioning will minimise the risk of fracture healing complications. Post-operative care should generally be unrestricted mobilization with weight bearing as tolerated.

Bone Screws↗
PubMed2001

A kinetic folding intermediate probed by native state hydrogen exchange.

Stopped-flow fluorescence studies on the N-terminal domain of rat CD2 (CD2.d1) have demonstrated that folding from the fully denatured state (U) proceeds via the transient accumulation of an apparent intermediate (I) in a so-called burst phase that precedes the rate-limiting transition leading to the native state (N). A previous pH-dependent equilibrium hydrogen exchange (HX) study identified a subset of amides in CD2.d1 which, under EX2 conditions, exchange from N with free energies greater than or equal to the free energy difference between the N and I states calculated from the stopped-flow data. Under EX1 conditions the rates of HX for these amides tend towards an asymptote that matches the global unfolding rate calculated from the stopped-flow data, suggesting that exchange for these amides requires traversing the N-to-I transition state barrier. Exchange for these amides presumably occurs from exchange-competent forms comprising the kinetic burst phase therefore. To explore this idea further, native state HX (NHX) data have been collected for CD2.d1 under EX2 conditions using denaturant concentrations which span either side of the denaturant concentration where, according to the stopped-flow data, the apparent U and I states are iso-energetic. The data fit to a two-component, sub-global (sg)/global (g) NHX mechanism, yielding Delta G and m value parameters (where the m value is a measure of hydrocarbon solvation). Regression analysis demonstrates that the (m(sg), Delta G(sg)) and (m(g), Delta G(g)) values calculated for this subset of amides correspond with those describing the kinetic burst phase transition. This result confirms the ability of the NHX technique to explore the structural and energetic properties of kinetic folding intermediates.

Animals↗
PubMed2001

Internal fixation implants for intracapsular proximal femoral fractures in adults.

BACKGROUND: Numerous different implants with screws, pins and side plates have been used for the internal fixation of intracapsular hip fractures. OBJECTIVES: To determine from randomised trials which implant is superior for the internal fixation of intracapsular proximal femoral fractures. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register. The date of the most recent search was December 2000. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing different implants for the internal fixation of intracapsular hip fractures in adults. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality, by use of a ten item scale, and extracted data. Additional information was sought from trialists. After grouping by implant type, comparable groups of trials were subgrouped and where appropriate, data were pooled using the fixed effects model. MAIN RESULTS: Twenty-seven studies involving 5269 participants (5274 fractures) were included in the study. Considerable variation in the quality of methodology between studies was found and biases due to familiarity with some of the implants were noted. None of the implants tested were found to be significantly superior for any of the outcome measures related to fracture healing complications or mortality. The sliding hip screw was found to take longer to insert and to have an increased operative blood loss compared with multiple screws or pins. REVIEWER'S CONCLUSIONS: No clear conclusions can be made on the choice of implant for internal fixation of intracapsular fractures from the available evidence within randomised trials.

Bone Nails↗
PubMed2001

Arthroplasties (with and without bone cement) for proximal femoral fractures in adults.

BACKGROUND: Numerous types of arthroplasties may be used in the surgical treatment of a hip fracture (proximal femoral fracture). The main differences between the implants are the design of the stems, whether the stem is fixed in place with or without cement, whether a second articulating joint is included within the prosthesis (bipolar prosthesis) or whether the whole hip joint is replaced. OBJECTIVES: To review all randomised trials that have compared different arthroplasties for the treatment of hip fractures in adults. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register. Additional trials were identified by searching reference lists of relevant articles, conference proceedings, and contact with trialists. Date of most recent search: January 2001. SELECTION CRITERIA: All randomised and quasi-randomised trials comparing different arthroplasties (and or cement), for the treatment of hip fractures. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality, by use of a ten-item checklist and extracted data. MAIN RESULTS: Thirteen trials involving 1464 patients were included. One trial investigated two comparisons. Cemented prostheses, when compared with uncemented (four trials, 391 participants) were associated with a lower risk of failure to regain mobility (relative risk (RR) 0.60, 95% confidence interval (CI) 0.44, 0.82) and of post-operation pain at a year or later (RR 0.51, 95% CI 0.31, 0.81). For this comparison, there were no significant differences in any other outcome. Comparison of unipolar hemiarthroplasty with bipolar hemiarthroplasty (six trials, 742 participants) showed no significant differences between the two types of implant. Two trials of 269 patients compared different types of hemiarthroplasty with a total hip replacement and two trials of 151 patients compared either different types of prosthesis head or different bipolar prostheses. Because of the limited number of cases and the use of different prostheses, no definite conclusions could be made from these four studies. REVIEWER'S CONCLUSIONS: Cementing prostheses in place seems to reduce pain post-operatively and results in better mobility, but because of the under-reporting of outcomes and the small number of patients involved, no definite conclusions can be made. The role of bipolar prostheses and total hip replacement is uncertain. Further well-conducted randomised trials are required.

Adult↗
PubMed2001

Closed suction surgical wound drainage after orthopaedic surgery.

BACKGROUND: Closed suction drainage systems are frequently used to drain fluids, particularly blood, from surgical wounds. The aim of these systems is to reduce the occurrence of wound haematomas and infection. OBJECTIVES: To evaluate the effectiveness of closed suction drainage systems for orthopaedic surgery. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register (May 2001), MEDLINE (1996-May 2001) and references from articles. SELECTION CRITERIA: All randomised or quasi-randomised trials comparing the use of closed suction drainage systems with no drainage systems for all types of elective and emergency orthopaedic surgery. DATA COLLECTION AND ANALYSIS: Both reviewers independently assessed trial quality, using a nine item scale, and extracted data. Wherever appropriate and possible, the data are presented graphically. MAIN RESULTS: Twenty-one studies involving 2772 patients with 2971 wounds were included in the analysis. The types of surgery involved were hip and knee replacement, shoulder surgery, hip fracture surgery, spinal surgery, cruciate ligament reconstruction, open meniscectomy and fracture fixation surgery. Many of the studies had poor methodology and reporting of outcomes. Pooling of results indicated no difference in the incidence of wound infection, haematoma or dehiscence between those allocated to drains and the un-drained wounds. There was a tendency to an increased risk of re-operation for wound complications in the group with drains (relative risk (RR) 2.25, 95% confidence intervals (CI) 0.95 to 5.33), but due to the small numbers of cases involved definite conclusions cannot be made for this outcome. Blood transfusion was required more frequently in those who received drains (RR 1.41, 95% CI 1.10 to 1.80). The need for reinforcement of wound dressings (RR 0.22, 95% CI 0.13 to 0.40) and bruising around the operation site was more common in the group without drains. REVIEWER'S CONCLUSIONS: There is insufficient evidence from randomised trials to support or refute the routine use of closed suction drainage in orthopaedic surgery. Further randomised trials are required before definite conclusions can be made.

Hematoma↗
PubMed2001

Current concepts in the treatment of hip fracture.

Clinicians involved in the care of hip fracture patients should move away from using treatments based on historical practices or local preferences, to those that are derived from careful evaluations and summaries of all previous medical research on that topic. For the busy clinician the use of summary articles, reviews and guidelines that are evidenced based are necessary to provide the best treatment available for the patient. Current practice indicates that the majority of hip fractures should be treated surgically, mobilised without restriction as soon as able and discharged home as soon a practicable. Given modern technology this should be possible for all patients.

Aged↗
PubMed2001

Does the level of an intracapsular femoral fracture influence fracture healing after internal fixation? A study of 411 patients.

The aim of the study was to determine if the level of an intracapsular femoral fracture influences the risk of non-union or avascular necrosis occurring after internal fixation. An observer blinded to the outcome of the treatment (fracture union, non-union or avascular necrosis) reviewed the radiographs of 411 patients with an intracapsular fracture, which had been treated by internal fixation. The level of the fracture was determined by two methods, a direct distance measurement and a ratio method. In addition, the diameter of the femoral head was measured. Results indicated that none of the methods for determining the fracture level had any relationship to the risk of non-union or avascular necrosis occurring. Undisplaced fractures were found to be more proximally located than displaced fractures. We conclude that the level of an intracapsular fracture should not be used as a method of deciding if the femoral head should be preserved or replaced. The level of an intracapsular fracture may determine if the fracture displaces at the time of injury.

Aged↗
PubMed2001

Results of the long Gamma nail for complex proximal femoral fractures.

The results for a series of 35 patients with complex proximal femoral fractures treated with the long Gamma nail are presented. Fracture healing occurred in all surviving patients, but there were four technical problems associated with the implant. Two nails broke associated with delayed union of the fracture necessitating revision of the implant, one fracture of femur at the site of distal locking occurred during surgery and there was one later fracture at the tip of the nail. All but one failures of fixation were revised with another Gamma nail and healed uneventfully. Overall the number of fracture healing complications compares favourably to contemporary implants and improvements in the design and strength of the nail may further improve results.

Adult↗
PubMed2001

Determinants of agonist binding affinity on neuronal nicotinic receptor beta subunits.

The alpha and beta subunits of heteromeric neuronal nicotinic acetylcholine receptors (nAChRs) are thought to contribute "principal" and "complementary" components to the agonist binding site, respectively. At least six loops of amino acid sequence (A, B, and C from alpha; D, E, and F from beta) are involved. We demonstrated previously that receptors containing the beta2 subunit had consistently higher affinities for a variety of agonists than beta4-containing receptors. For example, the affinity of the alpha2beta2 receptor for epibatidine, ACh, nicotine, and dimethylphenylpiperazinium (DMPP) exceeds that of alpha2beta4 by 9-, 61-, 87-, and 120-fold, respectively. Using saturation and competition analysis of receptors formed by chimeric beta subunits coexpressed with alpha2 in Xenopus laevis oocytes, we have now identified sequence segment 54-63 (corresponding to loop D) as a major determinant of affinity for epibatidine, ACh, nicotine, and DMPP. We then analyzed a series of mutant beta2 subunits in which each residue that differs between beta2 and beta4 in this region was changed from what occurs in beta2 to what occurs in beta4. The N55S, V56I, and E63T mutations each resulted in a loss of affinity for ACh and nicotine of 3- to 4-fold, whereas the T59K mutation resulted in a 7-fold loss of ACh and nicotine affinity. These mutations had little or no effect on epibatidine and DMPP affinity. The positive charge introduced by the T59K mutation does not appear to underlie loss of agonist affinity, because a similar loss of affinity was observed when a negative charge (T59D) was introduced at this position.

Animals↗
PubMed2000

A statistical appraisal of native state hydrogen exchange data: evidence for a burst phase continuum?

For a number of proteins, folding occurs via the rapid accumulation of secondary and tertiary structural features in a so-called burst phase, preceding the relatively slow, highly activated transition leading to the native state. A fundamental question is: do these burst phase reactions comprise two phase-separated thermodynamic states or a continuum of states? Ribonuclease HI (RNase H) from Escherichia coli and phage T4 lysozyme (T4L) both exhibit such a phenomenon. Native-state hydrogen exchange (NHX) data have been collected for these proteins, providing residue-specific free energies and m-values (a measure of hydrocarbon solvation) for the manifold of partially unfolded, exchange-competent forms that are accessible from the native state (DeltaG(sg) and m(sg), where the sg subscript denotes sub-global). There is good evidence that these parameters pertain to exchange-competent species comprising the burst phase observed in the global folding kinetics. We combine the results from the global folding kinetics of these proteins with a statistical analysis of their NHX parameters to determine if the distribution of experimental (m(sg), DeltaG(sg)) values derive from a mechanism where the burst phase is two-state. For RNase H, this analysis demonstrates that the burst phase of this protein is not two-state; the results imply a distribution of states, m and DeltaG exhibiting a linear functional relationship consistent with the global folding parameters. For T4L, it is difficult to distinguish the observed distribution of m(sg), DeltaG(sg) values from that expected for a mechanism where the burst phase is two-state. The results for RNase H* lend support for the idea that the burst phase reaction of this protein comprises a continuum of states. This has important implications for how we model the process of structural acquisition in protein folding reactions.

Bacteriophage T4↗
PubMed2000

Replacement arthroplasty versus internal fixation for extracapsular hip fractures.

BACKGROUND: Internal fixation, commonly used for extracapsular hip fractures, may fail particularly in unstable fractures. Replacement of the hip using arthroplasty, often used for intracapsular fractures, has been used as an alternative. OBJECTIVES: To compare replacement arthroplasty with internal fixation for the treatment of extracapsular hip fractures in adults. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group's trials register and bibliographies of published papers, and contacted colleagues. Date of the most recent search: August 1999. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing replacement arthroplasty with an internal fixation implant for skeletally mature patients with an extracapsular hip fracture. DATA COLLECTION AND ANALYSIS: Both reviewers independently assessed trial quality, using a ten item scale, and extracted data. Additional information was sought from trialists. Odds ratios and 99% confidence intervals were calculated for relevant dichotomous outcomes and presented graphically. MAIN RESULTS: Only one randomised trial of 90 patients with unstable extracapsular hip femoral fractures in the trochanteric region was identified and included in this review. This compared arthroplasty with a sliding hip screw and was of poor methodological quality. From the limited data available for this trial, there were no significant differences between the two methods of treatment for operating time, local wound complications, mortality rate or mobility of previously independent patients. There was however a reportedly higher blood transfusion need in the arthroplasty group. REVIEWER'S CONCLUSIONS: There is insufficient evidence from randomised trials to determine whether replacement arthroplasty has any advantage over the sliding hip screw for extracapsular hip fractures. Further well designed randomised trials for the treatment of these fractures for this comparison are required.

Fracture Fixation, Internal↗