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Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 393 - 393
1 Sep 2012
Zlowodzki M Wijdicks C Armitage B Cole P
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Introduction

Femoral neck fractures are a large clinical and economical problem. One of the most common fixation options for femoral neck fractures are multiple cancellous screws. A previous clinical study has shown the lack of washers to be the single largest predictor of fixation failure in the treatment of femoral neck fractures with cancellous screws. This finding was somewhat surprising as washers do not prevent the screws from backing out and do not provide any increase resistance to varus collapse. Therefore a follow-up biomechanical study was designed to test this observation. The purpose was to evaluate the maximal insertional torque of screws in osteoporotic bone with and without washers. We hypothesized that the lateral cortex of an osteoporotic proximal femur does not provide sufficient counter resistance for the screw heads to obtain maximum torque upon screw insertion in the femoral head and that the use of washers would increase screw purchase by providing a larger rigid surface area and subsequent higher counter resistance thereby allowing a higher maximal screw insertion torque.

Methods

We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Two screws each were inserted in each femur either with or without a washer and maximal insertional torque was measured using a 50 Nm torque transducer. The testing was performed using a customized device which allowed the torque transducer to apply a constant axial force and torque speed to the screws. A paired Student's t-test was used to compare the maximal screw insertional torque of screws with washers versus screws without washers in matched pairs.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 512 - 512
1 Sep 2012
Zlowodzki M Armitage B Wijdicks C Kregor P Bruce L Cole P
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Introduction

The most common treatment options for fixation of osteoporotic distal femur fractures are retrograde nails and locking plates. There are proponents of more elastic titanium plates as well as more rigid steel plates; No clear superiority of one over the other has been established. We aimed to evaluate the mechanical differences between stainless steel and titanium locking plates in the fixation of distal femur fractures in osteoporotic bone. We hypothesized that due to its higher elasticity titanium locking plates can absorb more energy and are therefore less likely to “cut” into the bone compared to stainless steel locking plates resulting in improved metaphyseal osteoporotic fracture fixation.

Methods

We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Within each pair we randomized one femur to be fitted with a Less Invasive Stabilization System (LISS-Titanium locking plate) and one with a Distal Locking Condylar Plate (DLCP-Stainless steel locking plate).

A fracture model simulating an AO 33-A3 fracture was created (extraarticular comminuted fracture) and specimens were subsequently subjected to step-wise cyclic axial loading to failure. We used an advanced three dimensional tracking system (Polhemus Fastrak) to monitor the movement of the distal fragment relative to the real time distal plate position allowing us to evaluate distal implant cut-out.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_II | Pages 275 - 275
1 May 2010
Zlowodzki M Can S Bandari M Klliainen L Shubert W
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Aims: Ulnar nerve compression at the elbow known as cubital tunnel syndrome is the second most common compression neuropathy of the upper limb. There is currently no consensus on the optimal operative treatment approach. The objective of this meta-analysis of randomized controlled trials was to evaluate the efficacy of simple decompression versus anterior transposition of the nerve in the treatment of cubital tunnel syndrome.

Methods: Multiple databases (Medline, Embase, Cochrane Library, Cinahl and several meeting archives) were searched for randomized controlled trials (RCTs) reporting on the outcome of operative treatment of cubital tunnel syndrome in patients with no trauma or previous surgeries. Two reviewers abstracted baseline characteristics, clinical scores and motor nerve conduction velocities independently. Data were pooled across studies, standard mean differences in effect sizes (SMD) weighted by study sample size were calculated and heterogeneity across studies was assessed.

Results: We identified four RCTs comparing simple decompression to anterior ulnar nerve transposition (two submuscular and two subcutaneous). Three studies used a clinical scoring system as the primary clinical outcome (n=261). There were no significant differences between simple decompression and anterior transposition. (SMD= − 0.04, 95%CI: −0.36 to 0.28, p=0.81). We did not find significant heterogeneity across studies (I2=34.2%; p=0.22). Two studies presented postoperative motor nerve conduction velocities (n=100) with no significant differences (SMD=0.24 in favor of simple decompression, 95%CI: −0.22 to 0.57, p=0.23; I2=0%; p=0.9).

Conclusions: The results of this meta-analysis suggests that there is no difference in motor nerve conduction velocities and clinical outcome scores between simple decompression and ulnar nerve transposition for the treatment of moderate to severe ulnar nerve compression at the elbow in patients with no prior trauma or previous surgeries to the affected elbow. Confidence intervals around the points of estimate are narrow probably excluding clinically meaningful differences. Since ulnar nerve transposition is the more invasive of the two procedures, this data supports the use of simple decompression of the ulnar nerve unless a plausible indication for ulnar nerve transposition exists.


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Purpose: The optimal treatment for displaced femoral neck fractures in patients aged 60–80 years is controversial. Orthopaedists that advocate for arthroplasty cite strong evidence that there is an increased revision rate with internal fixation. We aimed to explore patient preferences for the treatment of a displaced femoral neck fracture using a novel decision board approach.

Method: We developed a decision board presenting descriptions, expected outcomes, and potential complications of hemiarthroplasty and internal fixation for the treatment of displaced femoral neck fractures. 108 healthy volunteers were confronted with the scenario of sustaining a displaced femoral neck fracture and presented the decision board, then asked to state their preference for operative procedure, and describe the reasons for their choice.

Results: After application of the decision board with all outcomes presented for each alternative (internal fixation versus arthroplasty), 61/108 (56%) participants chose internal fixation over arthroplasty as their operative procedure of choice. Factors that contributed to this choice included: less blood loss (61%), shorter operation time (31%), less mortality (20%), and less invasive (18%). Participants who preferred arthroplasty (44%) did so primarily due to the lower re-operation rate (94%), better mobility (9%) and shorter hospital stay (4%).

Conclusion: Despite common surgeon preferences for arthroplasty, over half of participants preferred internal fixation due to less blood loss, shorter operative times, lower mortality, and less invasiveness. Surgeons should not assume that patients would prefer arthroplasty over internal fixation; the decision board can be an effective aid to incorporate patients’ preferences into the decision-making process.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 6 - 6
1 Mar 2010
Zlowodzki M Brink O Switzer J Wingerter S James J Bruinsma DR Petrisor BA Kregor PJ Bhandari M
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Purpose: Femoral neck fracture collapse and shortening has been a desired effect of parallel screw fixation to promote healing. While some degree of compression might be beneficial, it remains unknown whether the effects of uncontrolled femoral neck shortening leads to detectable functional impairment. We aimed to evaluate the effect of shortening and varus collapse after cancellous screw fixation of femoral neck fractures on patient functional status and quality of life.

Method: The databases of four University Hospitals were screened to identify patients with a healed isolated femoral neck fracture. Patients were contacted by telephone to complete Short-form 36(SF36) and Euroquol-5D(EQ5D) questionnaires (Primary outcome: SF36 physical functioning score[PF]). Femoral neck shortening and varus collapse were assessed by three independent reviewers blinded to functional outcome results based on the latest follow-up radiographs and categorized into three grades: None/Mild (within 5mm/5°), Moderate (5–10mm/5–10°), and Severe (> 10mm/> 10°). The minimal clinically important difference for SF36 PF score equals 12 points (1/2 of Standard deviation).

Results: Out of 660 patients screened at all four sites 70 met the inclusion criteria and were available for follow-up. The average follow-up was 20 months and an the average age was 71 years. Overall, there were 24/70 patients with none/mild femoral neck shortening, 25/70 with moderate shortening and 21/70 with severe shortening. Patients with severe shortening of their hip had significantly lower SF36 physical functioning scores (No/Mild vs. Severe shortening: 74 vs. 42 points, p=0.01). Similar important effects occurred with moderate shortening suggesting a gradient effect (No/Mild vs. Moderate shortening: 74 vs. 53 points). Some degree of varus collapse occurred in 39% of the patients and correlated moderately with the occurrence of shortening (r=0.66, p< 0.001).

Conclusion: A large proportion of displaced and undisplaced femoral neck fractures fixed with cancellous screws heal in a shortened position (66%) and varus (39%). The differences in function we observed represent patient important declines and suggest that uncontrolled sliding with cancellous screw fixation has limitations.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 18 - 18
1 Mar 2009
Poolman R Struijs P Krips R Sierevelt I Marti R Farrokhyar F Zlowodzki M Bhandari M
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Background: While surgical trials can rarely blind surgeons or patients, they can often blind outcome assessors. The aim of this systematic review was threefold:

1) to examine the reporting of outcome measures in orthopaedic trials,

2) to determine the feasibility of blinding in published orthopaedic trials and

3) to examine the association between the magnitude of treatment differences and methodological safeguards such as blinding.

Specifically, we focused on an association between blinding of outcome assessment and the size of the reported treatment effect; in other words: does blinding of outcome assessors matter?

Methods: We reviewed 32 identified RCTs published in the Journal of Bone and Joint Surgery (American Volume), in 2003 and 2004 for the appropriate use of outcome measures. These RCTs represented 3.4% (32/938) of all studies published during that time period. All RCTs were reviewed by two of us for:

1) the outcome measures used and

2) the use of a methodological safeguard: blinding.

We calculated the magnitude of treatment effect of blinded compared to un-blinded outcome assessors.

Results: The methodological validation and clinical usefulness of the clinician-based, patient-based, and generic outcome instruments varied. Ten of the 32 RCTs (31%) used a modified outcome instrument. Of these 10 trials, 4 (40%) failed to describe how the outcome instrument was modified. Nine (90%) of the 10 articles did not describe how their modified instrument was validated and retested. Sixteen (50%) of the 32 RCTs did not report blinding of outcome assessors where blinding would have been possible. Among those studies with continuous outcome measure, unblinded outcomes assessment was associated with significantly larger treatment effects (standardized mean difference 0.76 versus 0.25, p=0.01). Similarly, in those studies with dichotomous outcomes, unblinded outcomes assessments were associated with significantly greater treatment effects (Odds ratio 0.13 versus 0.42, unblinded versus blinded, p< 0.001). The ratio of odds ratios (unblinded to blinded) was 0.31 suggesting that unblinded outcomes assessment was associated with an exaggeration of the benefit of a treatment’s effectiveness in our cohort of studies.

Conclusion: Reported outcomes in RCTs are often modified and rarely validated. Half of the RCTs did not blind outcome assessors even though blinding of outcome assessors would have been feasible in each case. Treatment effects may be exaggerated if outcome assessors are unblinded. Emphasis should be placed on detailed reporting of outcome measures to facilitate generalization. Outcome assessors should be blinded where possible to prevent bias.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 18 - 18
1 Mar 2009
Poolman R Struijs P Krips R Sierevelt I Lutz K Zlowodzki M Bhandari M
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Background: The Levels of Evidence Rating System is widely believed to categorize studies by quality, with Level I studies representing the highest quality evidence. We aimed to determine the reporting quality of Randomised Controlled Trials (RCTs) published in the most frequently cited general orthopaedic journals.

Methods: Two assessors identified orthopaedic journals that reported a level of evidence rating in their abstracts from January 2003 to December 2004 by searching the instructions for authors of the four highest impact general orthopaedic journals. Based upon a priori eligibility criteria, two assessors hand searched all issues of the eligible journal from 2003–2004 for RCTs. The assessors extracted the demographic information and the evidence rating from each included RCT and scored the quality of reporting using the reporting quality assessment tool, which was developed by the Cochrane Bone, Joint and Muscle Trauma Group. Scores were conducted in duplicate, and we reached a consensus for any disagreements. We examined the correlation between the level of evidence rating and the Cochrane reporting quality score.

Results: We found that only the Journal of Bone and Joint Surgery–American Volume (JBJS-A) used a level of evidence rating from 2003 to 2004. We identified 938 publications in the JBJS-A from January 2003 to December 2004. Of these publications, 32 (3.4%) were RCTs that fit the inclusion criteria. The 32 RCTs included a total of 3543 patients, with sample sizes ranging from 17 to 514 patients. Despite being labelled as the highest level of evidence (Level 1 and Level II evidence), these studies had low Cochrane reporting quality scores among individual methodological safeguards. The Cochrane reporting quality scores did not differ significantly between Level I and Level II studies. Correlations varied from 0.0 to 0.2 across the 12 items of the Cochrane reporting quality assessment tool (p> 0.05). Among items closely corresponding to the Levels of Evidence Rating System criteria assessors achieved substantial agreement (ICC=0.80, 95%CI:0.60 to 0.90).

Conclusions: Our findings suggest that readers should not assume that

1) studies labelled as Level I have high reporting quality and

2) Level I studies have better reporting quality than Level II studies.

One should address methodological safeguards individually.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 111 - 112
1 Mar 2009
Poolman R Sierevelt I Farrokhyar F Mazel J Blankevoort L Zlowodzki M Bhandari M
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Background: The Journal of Bone and Joint Surgery, American Edition (the Journal) recently initiated a section called “Evidence-Based Orthopaedics”. Furthermore, a Levels of Evidence rating is now used in the Journal to help readers in clinical decision-making. Little is known if this recent emphasis of Evidence-based Medicine (EBM) influenced surgeons’ perceptions about and competence in evidence-based medicine. Therefore, we examined perceptions and competence in evidence-based medicine among Dutch orthopaedic surgeons.

Methods: Members of the Dutch Orthopaedic Association were surveyed to examine surgeons’ attitudes towards evidence-based medicine and competence in evidence-based medicine. We evaluated perceptions using a newly developed instrument tailored to surgical practice. Univariate analysis, and a multivariable analysis using Generalized Estimating Equations were performed to model the competence instrument.

Results: 367 Surgeons responded (60%). Orthopaedic surgeons welcomed evidence-based medicine. Practical evidence-based medicine resources were perceived as the best methods to move from eminence-based to evidence-based practice. Four variables were significantly and positively associated with the competence instrument:

1) younger age, particularly age between 36 and 45 years,

2) experience of less than 10 years,

3) having a PhD degree, and

4) working in an academic or teaching setting.

The majority of the respondents (65%) were aware of the Journal’s evidence-based medicine section, and 20% used the Journal’s evidence-based medicine abstracts in clinical decision-making. This increased awareness in evidence-based medicine was also reflected in a frequent use of Cochrane reviews in clinical decision-making (27%). Surgeons who used the Journal’s evidence-based medicine abstracts and Cochrane reviews had significantly higher competence scores.

Conclusions: Evidence-based medicine is welcomed by Dutch orthopaedic surgeons. Recent emphasis of evidence-based medicine is reflected in an increased awareness about the Journal’s evidence-based medicine section, Levels of Evidence, and the largest evidence-based medicine resource: Cochrane reviews. Younger orthopaedic surgeons had better knowledge about evidence-based medicine. Development and use of evidence-based resources as well as pre-appraised summaries like the Journal’s evidence-based medicine abstracts and Cochrane reviews were perceived as the best way to move from eminence based- to evidence-based orthopaedic practice.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 349 - 349
1 Mar 2004
Zlowodzki M Williamson S Zardiackas L Kregor P
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Aims: Loss of distal þxation occurs with this the blade plate, especially in the setting of a very distal femur fracture and/or in osteoporotic bone. The LISS (Less Invasive Stabilization System) provides a þxation construct for supracondylar/intracondylar distal femoral fractures, with features including submuscular þxation and percutaneous placement of self-drilling unicortical þxed angled screws. The purpose of this study was to evaluate the biomechanical characteristics of the LISS versus the angled blade plate in an osteoporotic human cadaveric femoral model. Methods: Twenty-four matched pairs of fresh frozen human femora were utilized. Three groups of eight pairs each were tested to failure in one-time axial loading, one-time torsional loading and cyclical axial loading. A fracture model was created to simulate an AO 33–A3 fracture. Results: The average axial load to failure was 34% higher for the LISS compared with the blade plate (p = 0.03). All 8 LISS constructs failed by plastic deformation of the implant only, while 3/8 blade plates failed by loss of distal þxation. The blade plate had a 47% higher torsional moment to failure (p= 0.05). Permanent deformation after cyclical axial loading was signiþcantly lower for the LISS (p = 0.01). Conclusions: Of signiþcant interest is potential loss of þxation in catastrophic loading of a supracondylar femoral fracture þxation construct. In conclusion, biomechanical testing of the LISS demonstrates in comparison to the blade plate: (1) superior þxation of the distal femoral Ç block È in axial loading, (2) lower torsional strength, and (3) less permanent deformation in cyclical axial loading. The results further indicate that one-time axial loading of the LISS þxation construct will ultimately result in þxator plastic deformation, rather than screw pullout.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 349 - 349
1 Mar 2004
Zlowodzki M Vogt D Cole P Kregor P
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Aims: Published series of traditional plate þxation of the femur note rates of up to 69% primary bone grafting, 13% infection, 15% nonunion, 68% late complications, and 25% secondary surgical procedures. A shift from traditional plating to submuscular plating has thus ensued. This series entails an all-inclusive review of the plate þxation experience by two orthopaedic trauma surgeons in a þve-year period at a university trauma center. Methods: Between June 1996 and May 2001, 40 acute diaphyseal femoral fractures in 37 patients were managed utilizing dynamic compression plating via traditional Ç biological È plating with a formal lateral incision (n = 19), or submuscular plate þxation utilizing only a proximal and distal incision (n = 21). A comparison of reduction quality, union rates, and infection rates between traditional plate þxation and submuscular þxation was performed. Results: Thirty-nine of forty femoral shaft fractures healed without need of a secondary procedure. One nonunion occurred in the ORIF group. There was one infection in each group. Two patients treated by submuscular þxation developed signiþcant heterotopic ossiþcation around the femoral shaft which signiþcantly impaired knee motion. There were 6 cases of malreduction in the submuscular group, and none in the ORIF Group. Conclusions: Although the theoretical advantages of submuscular plating are well established, its utilization in the femoral shaft did not have a clear clinical advantage. In addition, its use appears to be more technically challenging, and is associated with a high rate of sub-optimal reductions.