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Migration and head penetration of Vitamin-E diffused cemented polyethylene cup compared to standard cemented cup in total hip arthroplasty: study protocol for a randomised, double-blind, controlled trial (E1 HIP).

ABSTRACT: INTRODUCTION:In vitro, Vitamin-E-diffused, highly cross-linked polyethylene (PE) has been shown to have superior wear resistance and improved mechanical properties when compared to those of standard highly cross-linked PE liners used in total hip arthroplasty (THA). The aim of the study is to evaluate the safety of a new cemented acetabular cup with Vitamin-E-doped PE regarding migration, head penetration and clinical results. METHODS AND ANALYSIS:In this single-centre, double-blinded, randomised controlled trial, we will include 50 patients with primary hip osteoarthritis scheduled for THA and randomise them in a 1:1 ratio to a cemented cup with either argon gas-sterilised PE (control group) or Vitamin-E-diffused PE (vitamin-e group). All patients and the assessor of the primary outcome will be blinded and the same uncemented stem will be used for all participants. The primary end point will be proximal migration of the cup at 2?years after surgery measured with radiostereometry. Secondary end points include proximal migration at other follow-ups, total migration, femoral head penetration, clinical outcome scores and hip-related complications. Patients will be followed up at 3?months and at 1, 2, 5 and 10?years postoperatively. RESULTS:Results will be analysed using 95% CIs for the effect size. A regression model will also be used to adjust for stratification factors. ETHICS AND DISSEMINATION:The ethical committee at Karolinska Institutet has approved the study. The first results from the study will be disseminated to the medical community via presentations and publications in relevant medical journals when the last patient included has been followed up for 2?years. TRIAL REGISTRATION NUMBER:NCT02254980.

SUBMITTER: Skoldenberg O

PROVIDER: S-EPMC4947731 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Migration and head penetration of Vitamin-E diffused cemented polyethylene cup compared to standard cemented cup in total hip arthroplasty: study protocol for a randomised, double-blind, controlled trial (E1 HIP).

Sköldenberg Olof O Rysinska Agata A Chammout Ghazi G Salemyr Mats M Muren Olle O Bodén Henrik H Eisler Thomas T

BMJ open 20160707 7

<h4>Introduction</h4>In vitro, Vitamin-E-diffused, highly cross-linked polyethylene (PE) has been shown to have superior wear resistance and improved mechanical properties when compared to those of standard highly cross-linked PE liners used in total hip arthroplasty (THA). The aim of the study is to evaluate the safety of a new cemented acetabular cup with Vitamin-E-doped PE regarding migration, head penetration and clinical results.<h4>Methods and analysis</h4>In this single-centre, double-bli ...[more]

PMID: 27388352

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Project description:BackgroundThe primary aim of this study was to compare the functional outcome of uncemented with cemented total hip arthroplasty (THA) for displaced intracapsular hip fractures. The secondary aims were to assess length of surgery, blood loss, complications and revision rate between the two groups.MethodsA prospective double-blind randomised control trial was conducted. Fifty patients with an intracapsular hip fracture meeting the inclusion criteria were randomised to either an uncemented (n = 25) or cemented (n = 25) THA. There were no differences (p > 0.45) in age, gender, health status or preinjury hip function between the groups. The Oxford hip score (OHS), Harris Hip score (HHS), EuroQol 5-dimensional (EQ5D), timed get up-and-go (TUG), pain and patient satisfaction were used to assess outcome. These were assessed at 4, 12 and 72 months after surgery, apart from the TUG which as only assessed as 6 months.ResultsThe study was terminated early due to the significantly (n = 8, p = 0.004) higher rate of intraoperative complications in the uncemented group: three fractures of the proximal femur and five conversions to a cemented acetabular component. There were no significant (p ≥ 0.09) differences in the functional measures (OHS, HSS, EQ5D, TUG and pain) or patient satisfaction between the groups. There was no difference in operative time (p = 0.75) or blood loss (p = 0.66) between the groups. There were two early revisions prior to 3 months post-operatively in the uncemented group and none in the cemented group, but this was not significant (log rank p = 0.16).ConclusionThere was a high rate of intraoperative complications, which may be due to poor bone quality in this patient group. There were no ergonomic or functional advantages demonstrated between uncemented and cemented THA. Cemented THA should remain as the preferred choice for the treatment of intracapsular hip fractures for patients that meet the criteria for this procedure.

Project description:Several studies have demonstrated a correlation between the acetabular cup position and the risk of dislocation, wear and range of motion after total hip arthroplasty. The present study was designed to evaluate the accuracy of the surgeon's estimated position of the cup after freehand placement in total hip replacement. Peroperative estimated abduction and anteversion of 200 acetabular components (placed by three orthopaedic surgeons and nine residents) were compared with measured outcomes (according to Pradhan) on postoperative radiographs. Cups were placed in 49.7 degrees (SD 6.7) of abduction and 16.0 degrees (SD 8.1) of anteversion. Estimation of placement was 46.3 degrees (SD 4.3) of abduction and 14.6 degrees (SD 5.9) of anteversion. Of more interest is the fact that for the orthopaedic surgeons the mean inaccuracy of estimation was 4.1 degrees (SD 3.9) for abduction and 5.2 degrees (SD 4.5) for anteversion and for their residents this was respectively, 6.3 degrees (SD 4.6) and 5.7 degrees (SD 5.0). Significant differences were found between orthopaedic surgeons and residents for inaccuracy of estimation for abduction, not for anteversion. Body mass index, sex, (un)cemented fixation and surgical approach (anterolateral or posterolateral) were not significant factors. Based upon the inaccuracy of estimation, the group's chance on future cup placement within Lewinnek's safe zone (5-25 degrees anteversion and 30-50 degrees abduction) is 82.7 and 85.2% for anteversion and abduction separately. When both parameters are combined, the chance of accurate placement is only 70.5%. The chance of placement of the acetabular component within 5 degrees of an intended position, for both abduction and anteversion is 21.5% this percentage decreases to just 2.9% when the tolerated error is 1 degrees . There is a tendency to underestimate both abduction and anteversion. Orthopaedic surgeons are superior to their residents in estimating abduction of the acetabular component. The results of this study indicate that freehand placement of the acetabular component is not a reliable method.

Project description:BackgroundMedialization of the cup with a respective increase in femoral offset has been proposed in THA to increase abductor moment arms. Insofar as there are potential disadvantages to cup medialization, it is important to ascertain whether the purported biomechanical benefits of cup medialization are large enough to warrant the downsides; to date, studies regarding this question have disagreed.Questions/purposesThe purpose of this study was to quantify the effect of cup medialization with a compensatory increase in femoral offset compared with anatomic reconstruction for patients undergoing THA. We tested the hypothesis that there is a (linear) correlation between preoperative anatomic parameters and muscle moment arm increase caused by cup medialization.MethodsFifteen patients undergoing THA were selected, covering a typical range of preoperative femoral offsets. For each patient, a finite element model was built based on a preoperative CT scan. The model included the pelvis, femur, gluteus minimus, medius, and maximus. Two reconstructions were compared: (1) anatomic position of the acetabular center of rotation, and (2) cup medialization compensated by an increase in the femoral offset. Passive abduction-adduction and flexion-extension were simulated in the range of normal gait. Muscle moment arms were evaluated and correlated to preoperative femoral offset, acetabular offset, height of the greater trochanter (relative to femoral center of rotation), and femoral antetorsion angle.ResultsThe increase of muscle moment arms caused by cup medialization varied among patients. Muscle moment arms increase by 10% to 85% of the amount of cup medialization for abduction-adduction and from -35% (decrease) to 50% for flexion-extension. The change in moment arm was inversely correlated (R(2) = 0.588, p = 0.001) to femoral antetorsion (anteversion), such that patients with less femoral antetorsion gained more in terms of hip muscle moments. No linear correlation was observed between changes in moment arm and other preoperative parameters in this series.ConclusionsThe benefit of cup medialization is variable and depends on the individual anatomy.Clinical relevanceCup medialization with compensatory increase of the femoral offset may be particularly effective in patients with less femoral antetorsion. However, cup medialization must be balanced against its tradeoffs, including the additional loss of medial acetabular bone stock, and eventual proprioceptive implications of the nonanatomic center of rotation and perhaps joint reaction forces. Clinical studies should better determine the relevance of small changes of moment arms on function and joint reaction forces.

Dataset Information

Migration and head penetration of Vitamin-E diffused cemented polyethylene cup compared to standard cemented cup in total hip arthroplasty: study protocol for a randomised, double-blind, controlled trial (E1 HIP).

Publications

Migration and head penetration of Vitamin-E diffused cemented polyethylene cup compared to standard cemented cup in total hip arthroplasty: study protocol for a randomised, double-blind, controlled trial (E1 HIP).

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