Medical Studies

Staples significantly increase risk of postoperative infection study

March 2010 Original Link  http://www.orthosupersite.com/view.aspx?rid=62584

The use of staples to close wounds following orthopedic surgery - especially hip surgery - is associated with a significantly greater risk of wound infection than traditional suturing, according to orthopedic researchers from Norwich, England.

Six clinical trials

Toby O. Smith, MSc, BSc (Hons), MCSP, and colleagues analyzed the results of six trials that compared staples and sutures used for wound closure following orthopedic procedures in adult patients. The six clinical trials involved 683 wounds. Of these cases, 322 patients underwent suture closure and 351 patients had staple closure, according to a British Medical Journal press release.

The authors found that wounds closed with staples were more than three times as likely to develop a superficial wound infection compared to wounds closed with sutures. In a subgroup analysis of patients undergoing hip surgery, the risk of developing a wound infection was found to be four times greater after staple closure than suture closure, according to the release.

Staples not recommended

The researchers found no significant difference between staples and sutures in the development of inflammation, discharge, dehiscence, necrosis and allergic reaction.

The authors called for high quality, well-designed trials to confirm their findings.

Although the quality of evidence from the six trials was generally poor, the authors concluded, "With the current evidence, however, patients and doctors should think more carefully about the use of staples for wound closure after hip and knee surgery."

•Reference:
Smith TO, Sexton D, Mann C, et al. Sutures versus staples for skin closure in orthopaedic surgery: meta-analysis. BMJ. [Published online ahead of print March 16, 2010]

A Modified Posterior Approach Preserves Femoral Head Oxgenation During Hip Resurfacing 2010

Steffen RT, De Smet KA, Murray DW, Gill HS  2010 Mar 22

Original Link  http://www.ncbi.nlm.nih.gov/pubmed/20334994?dopt=AbstractPlus

Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK.

In 11 patients, the oxygenation was measured in the superolateral quadrant of the femoral head during resurfacing with a modified posterior approach, designed to preserve the blood supply, using a gas-sensitive electrode. These were compared with measures from 10 patients in whom the standard posterior approach was used. The modified approach patients maintained a significantly (P < .005) higher amount of relative oxygenation after the approach, 78% (standard deviation [SD], 45%) vs 38% (SD, 26%), and acetabular component implantation, 74% (SD, 56%) vs 20% (SD, 28%). The modified posterior approach, unlike the standard extended approach, does not significantly compromise the blood supply to the head; and we recommend this approach be considered for hip resurfacing.

Does commitment to rehabilitation influence the clinical outcome of total hip resurfacing arthroplasty study 2010

Link to original medical study

The purpose of this study was to evaluate whether compliance and rehabilitative efforts were predictors of early clinical outcome of total hip resurfacing arthroplasty.

Methods: A cross-sectional survey was utilized to collect information from 147 resurfacing patients, who were operated on by a single surgeon, regarding their level of commitment to rehabilitation following surgery. Patients were followed for a mean of 52 months (range, 24 to 90 months).

Clinical outcomes and functional capabilities were assessed utilizing the Harris hip objective rating system, the SF-12 Health Survey, and an eleven-point satisfaction score. A linear regression analysis was used to determine whether there was any correlation between the rehabilitation commitment scores and any of the outcome measures, and a multivariate regression model was used to control for potentially confounding factors.

Results: Overall, an increased level of commitment to rehabilitation was positively correlated with each of the following outcome measures: SF-12 Mental Component Score, SF-12 Physical Component Score, Harris Hip score, and satisfaction scores.

These correlations remained statistically significant in the multivariate regression model.

Conclusions: Patients who were more committed to their therapy after hip resurfacing returned to higher levels of functionality and were more satisfied following their surgery.

Author: David MarkerThorsten SeylerAnil BhaveMichael ZywielMichael Mont
Credits/Source: Journal of Orthopaedic Surgery and Research 2010, 5:20

Sports Activity After Total Hip Resurfacing Study 2010

Original Link http://www.ncbi.nlm.nih.gov/pubmed/20223940?dopt=Abstract

March 11, 2010

Banerjee M, Bouillon B, Banerjee C, Bäthis H, Lefering R, Nardini M, Schmidt J.
Dreifaltigkeits-Krankenhaus and Cologne Merheim Medical Center.

BACKGROUND: Little is known about sports activity after total hip resurfacing.

HYPOTHESIS: Patients undergoing total hip resurfacing can have a high level of sports activity. STUDY DESIGN: Case series; Level of evidence, 4.

METHODS: The authors evaluated the level of sports activities with a standardized questionnaire in 138 consecutive patients (152 hips) 2 years after total hip resurfacing. Range of motion, Harris hip score, and Oxford score were assessed, and radiological analysis was performed.

RESULTS:  Preoperatively, 98% of all patients participated in sports activities. Two years postoperatively, 98% of the patients participated in at least 1 sports activity. The level of sports activity decreased after surgery. The number of sports activities per patient decreased from 3.6 preoperatively to 3.2 postoperatively. Intermediate- and high-impact sports, especially tennis, soccer, jogging, squash, and volleyball, showed a significant decrease while the low-impact sports (stationary cycling, Nordic walking, and fitness/weight training) showed a significant increase. Physical activity level at the time of follow-up as measured by the Grimby scale was significantly higher than in the year before surgery. Duration of sports participation per week increased significantly after surgery. Men had a significantly higher sport level than women before and after surgery. Eighty-two percent felt no restriction while performing sports. One-third missed certain sports activities such as jogging, soccer, tennis, and downhill skiing. The Harris hip and Oxford scores showed a significant increase postoperatively.

CONCLUSION: The results of this short-term follow-up study show that sports activity after total hip resurfacing surgery is still possible. Physical activity level increased with a shift toward low-impact sports. Duration of sports participation increased. High-impact sports activities decreased. These findings  can be important for the decision-making process for hip surgery and should be communicated to the patient.

Hospitals more specialized in orthopedic surgery show better outcomes for hip and knee replacement

 February 17, 2010  Click Here to read full article

A recent study of Medicare data by University of Iowa investigators indicates that hospitals with a higher degree of orthopedic specialization provide better outcomes for patients undergoing hip or knee replacement surgery.

The findings, which appear in the online version of the British Medical Journal, were based on a retrospective study of nearly 1.3 million Medicare beneficiaries aged 65 years and older who had hip or knee replacement procedures between 2001 and 2005 at 3,818 U.S. hospitals. The investigators grouped the hospitals into five categories according to their degree of orthopedic specialization. Orthopedic procedures accounted for 10.5% of admissions at the average hospital, while they represented 14.5% or more of the admissions in the most specialized group...

..."The findings suggest that more specialized hospitals have better outcomes even after we account for the type of patients each hospital cares for and the number of hip and knee replacement surgeries that each hospital performs," Tyson Hagen, MD, the lead author of the study, stated in the release...

Reference: Hagen TP, Vaughan-Sarrazin MS, Cram P. Relation between hospital orthopaedic specialisation and outcomes in patients aged 65 and older: retrospective analysis of US Medicare data. BMJ. Published online 2010 Feb 11.

Antibiotic Prophylaxis for Bacteremia in Patients with Joint Replacements by AAOS

February 2009 American Academy of Orthopaedic Surgeons

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This statement provides recommendations to supplement practitioners in their clinical judgment regarding antibiotic prophylaxis for patients with a joint prosthesis. It is not intended as the standard of care nor as a substitute for clinical judgment as it is impossible to make recommendations for all conceivable clinical situations in which bacteremias may occur. The treating clinician is ultimately responsible for making treatment recommendations for his/her patients based on the clinician’s professional judgment.

Any perceived potential benefit of antibiotic prophylaxis must be weighed against the known risks of antibiotic toxicity, allergy, and development, selection and transmission of microbial resistance. Practitioners must exercise their own clinical judgment in determining whether or not antibiotic prophylaxis is appropriate.

More than 1,000,000 total joint arthroplasties are performed annually in the United States, of which approximately 7 percent are revision procedures.1 Deep infections of total joint replacements usually result in failure of the initial operation and the need for extensive revision, treatment and cost. Due to the use of perioperative antibiotic prophylaxis and other technical advances, deep infection occurring in the immediate postoperative period resulting from intraoperative contamination has been markedly reduced in the past 20 years...

...Patients with joint replacements who are having invasive procedures or who have other infections are at increased risk of hematogenous seeding of their prosthesis. Antibiotic prophylaxis may be considered, for those patients who have had previous prosthetic joint infections, and for those with other conditions that may predispose the patient to infection. There is evidence that some immunocompromised patients with total joint replacements may be at higher risk for hematogenous infections. However, patients with pins, plates and screws, or other orthopaedic hardware that is not within a synovial joint are not at increased risk for hematogenous seeding by microorganisms...

...Given the potential adverse outcomes and cost of treating an infected joint replacement, the AAOS recommends that clinicians consider antibiotic prophylaxis for all total joint replacement patients prior to any invasive procedure that may cause bacteremia.

The Influence of Head Size and Sex on the Outcome of Birmingham Hip Resurfacing

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 The Journal of Bone and Joint Surgery (American). 2010
Callum W. McBryde, MD, FRCS(Tr&Orth)1, Kanthan Theivendran, MRCS1, Andrew M.C. Thomas, FRCS1, Ronan B.C. Treacy, FRCS(Tr&Orth)1 and Paul B. Pynsent, PhD1

1 Research and Teaching Centre, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. E-mail address for C.W. McBryde: cwmcbryde@hotmail.com

Investigation performed at the Royal Orthopaedic Hospital, Birmingham, United Kingdom

Background Hip resurfacing has gained popularity for the treatment of youngand active patients who have arthritis. Recent literature has demonstrated an increased rate of revision among female patients as compared with male patients who have undergone hip resurfacing. The aim of the present study was to identify any differences in survival or functional outcome between male and female patients with osteoarthritis who were managed with metal-on-metal hip resurfacing.

Methods A prospective collection of data on all patients undergoing Birmingham Hip Resurfacing at a single institution was commenced in July 1997. On the basis of the inclusion and exclusion criteria,1826 patients (2123 hips, including 799 hips in female patients and 1324 hips in male patients) with a diagnosis of osteoarthritis who had undergone the procedure between July 1997 and December2008 were identified. The variables of age, sex, preoperative Oxford Hip Score, component size used, surgical approach, lead surgeon, and surgeon experience were analyzed. A multivariate Cox proportional hazard survival model was used to identify which variables were most influential for determining revision.

Results The mean duration of follow-up was 3.46 years (range, 0.03 to10.9 years). The five-year cumulative survival rate for the655 hips that were followed for a minimum of five years was 97.5% (95% confidence interval, 96.3% to 98.3%). There were forty-eight revisions. Revision was significantly associated with female sex (hazard rate, 2.03 [95% confidence interval,1.15 to 3.58]; p = 0.014) and decreasing femoral component size hazard rate per 4-mm decrease in size, 4.68 [95% confidence interval, 4.36 to 5.05]; p < 0.001). Revision was not associated with age (p = 0.88), surgeon (p = 0.41), surgeon experience (p = 0.30), or surgical approach (p = 0.21). A multivariate analysis including the covariates of sex, age, surgeon, surgeon experience, surgical approach, and femoral component size demonstrated that sex was no longer significantly associated with revision when femoral component size was included in the model (p = 0.37).Femoral component size alone was the best predictor of revision when all covariates were analyzed (hazard rate per 4-mm decrease in size, 4.87 [95% confidence interval, 4.37 to 5.42]; p <0.001).

Conclusions The present study demonstrates that although female patients initially may appear to have a greater risk of revision, this increased risk is related to differences in the femoral component size and thus is only indirectly related to sex. Patient selection for hip resurfacing is best made on the basis of femoral head size rather than sex.

Surgery hits hip pocket

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By Sue Dunlevy From: The Daily Telegraph January 04, 2010

ONE in every 12 hip and knee replacements need corrective operations and new surgical techniques are more susceptible to problems, according to Australia's largest health insurer. Medibank Private has reviewed its data on the 3990 hip replacements and 4860 knee replacements it paid for in 2008 and found "on average surgeons perform revisions on 8.3 per cent of their total procedures"...

...The National Joint Replacement Registry, which is studying the reliability of hip and knee replacements, has found newer joint replacements that are cementless or hybrid are more likely to need further surgery than the older cemented replacements...

...And research found the more reliable cement joint replacements are used in just 23 per cent of hip replacement operations...

...The latest report from the National Joint Replacement Registry found that three types of hip replacements - the ASR, Durom and Recap hip replacements - had more than twice the risk of revision of other resurfacing prostheses. Hip replacements with smaller femoral head sizes are also more likely to be revised.

The Allegretto knee, one of the most common knee-replacements used in Australia, has a 10 per cent revision rate at 2.5 years, which is considerably greater than other similar prostheses.

 

"The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear"

Presented at the 2nd Annual Total Hip Resurfacing Arthroplasty Course in LA Oct. 2008

By: John Fisher
Co-Authors: Ian Leslie, Sophie Williams, Eileen Ingham, Graham Isaac
Institute of Medical and Biological Engineering
University of Leeds

Background: There are considerable variations in metal ion levels and metallic wear rates in patients with metal on metal resurfacing. In this in vitro study the effect of design variables of head diameter and bearing clearance and patient variables of cup and head position on metal ion levels and wear rates are were investigated. Methods: Hip joint simulator studies were carried out on size 39mm and size 55mm metal on metal resurfacing with the same design. Size 55mm diameter bearings with 110 micrometer diametrical clearance were compared to size 54mm diameter with larger >250 micrometer diametrical clearance. The wear rates of size 39mm bearings with a standard cup position of 45 degrees, were compared to a steep cup position of 60 degrees and to a steep cup position combined with micro separation associated with head offset deficiency.

Results: Initial bedding in wear rates and ion levels were higher with size 39mm bearings compared to size 55mm, but in long term after 15 million cycles there was no difference in the steady state wear rates. Bearings with the larger diametrical clearance had higher initial wear and steady state wear rates at five million cycles. Cup position and head position resulted in much greater increases in wear. For the 39 mm bearings, a 60 degree cup position resulted in a 9 fold increase in wear. A steep cup and microseparation resulted in a 17 fold increase in wear after two million cycles and a 39 fold increase in wear compared to the long term steady state wear rate.

Conclusions: The study confirmed clinical ion level studies of increased wear with larger clearance bearings. The results also confirm clinical ion level measurements that steep cup angles can substantially increases wear. The study also indicates that offset deficiency and microseparation may be responsible for extremely high wear rates and ion levels found in some retrievals and some patients. Further work is needed to investigate effect of different head sizes with steep cups and microseparation and the effect of version.