Advertisement for orthosearch.org.uk
Results 1 - 43 of 43
Results per page:
The Bone & Joint Journal
Vol. 105-B, Issue 3 | Pages 261 - 268
1 Mar 2023
Ruhr M Huber G Niki Y Lohner L Ondruschka B Morlock MM

Aims. The aim of the study was to investigate whether the primary stability of press-fit acetabular components can be improved by altering the impaction procedure. Methods. Three impaction procedures were used to implant acetabular components into human cadaveric acetabula using a powered impaction device. An impaction frequency of 1 Hz until complete component seating served as reference. Overimpaction was simulated by adding ten strokes after complete component seating. High-frequency implantation was performed at 6 Hz. The lever-out moment of the acetabular components was used as measure for primary stability. Permanent bone deformation was assessed by comparison of double micro-CT (µCT) measurements before and after impaction. Acetabular component deformation and impaction forces were recorded, and the extent of bone-implant contact was determined from 3D laser scans. Results. Overimpaction reduced primary acetabular component stability (p = 0.038) but did not significantly increase strain release after implantation (p = 0.117) or plastic deformations (p = 0.193). Higher press-fits were associated with larger polar gaps for the 1 Hz reference impaction (p = 0.002, R. 2. = 0.77), with a similar trend for overimpaction (p = 0.082, R. 2. = 0.31). High-frequency impaction did not significantly increase primary stability (p = 0.170) at lower impaction forces (p = 0.001); it was associated with smaller plastic deformations (p = 0.035, R. 2. = 0.34) and a trend for increased acetabular component relaxation between strokes (p = 0.112). Higher press-fit was not related to larger polar gaps for the 6 Hz impaction (p = 0.346). Conclusion. Overimpaction of press-fit acetabular components should be prevented since additional strokes can be associated with increased bone damage and reduced primary stability as shown in this study. High-frequency impaction at 6 Hz was shown to be beneficial compared with 1 Hz impaction. This benefit has to be confirmed in clinical studies. Cite this article: Bone Joint J 2023;105-B(3):261–268


The Bone & Joint Journal
Vol. 102-B, Issue 7 Supple B | Pages 71 - 77
1 Jul 2020
Gonzalez Della Valle A Shanaghan KA Nguyen J Liu J Memtsoudis S Sharrock NE Salvati EA

Aims. We studied the safety and efficacy of multimodal thromboprophylaxis in patients with a history of venous thromboembolism (VTE) who undergo total hip arthroplasty (THA) within the first 120 postoperative days, and the mortality during the first year. Multimodal prophylaxis includes discontinuation of procoagulant medications, VTE risk stratification, regional anaesthesia, an intravenous bolus of unfractionated heparin prior to femoral preparation, rapid mobilization, the use of pneumatic compression devices, and chemoprophylaxis tailored to the patient’s risk of VTE. Methods. Between 2004 to 2018, 257 patients with a proven history of VTE underwent 277 primary elective THA procedures by two surgeons at a single institution. The patients had a history of deep vein thrombosis (DVT) (186, 67%), pulmonary embolism (PE) (43, 15.5%), or both (48, 17.5%). Chemoprophylaxis included aspirin (38 patients), anticoagulation (215 patients), or a combination of aspirin and anticoagulation (24 patients). A total of 50 patients (18%) had a vena cava filter in situ at the time of surgery. Patients were followed for 120 days to record complications, and for one year to record mortality. Results. Postoperative VTE was diagnosed in seven patients (2.5%): DVT in five, and PE with and without DVT in one patient each. After hospitalization, three patients required readmiss-ion for evacuation of a haematoma, one for wound drainage, and one for monitoring of an elevated international normalized ratio (INR). Seven patients died (2.5%). One patient died five months postoperatively of a PE during open thrombectomy. She had discontinued anticoagulation. One patient died of a haemorrhagic stroke while receiving Coumadin. PE or bleeding was not suspected in the remaining five fatalities. Conclusion. Multimodal prophylaxis is safe and effective in patients with a history of VTE. Postoperative anticoagulation should be prudent as very few patients developed VTE (2.5%) or died of suspected or confirmed PE. Mortality during the first year was mostly unrelated to either VTE or bleeding. Cite this article: Bone Joint J 2020;102-B(7 Supple B):71–77


The Bone & Joint Journal
Vol. 100-B, Issue 4 | Pages 436 - 442
1 Apr 2018
Choi HG Lee YB Rhyu SH Kwon BC Lee JK

Aims. The aim of this study was to compare the rate of mortality and causes of death in Korean patients who undergo surgery for a fracture of the hip, up to 11 years after the injury, with a control group from the general population. Materials and Methods. National cohort data from Korean Health Insurance Review and Assessment Service – National Sample Cohort were used. A ratio of 1:4 matched patients with a fracture who underwent surgery (3383, fracture group) between 2003 and 2012, and controls (13 532) were included. The matches were processed for age, gender, income, and region of residence. We also undertook analyses of subgroups according to age and gender. The mean follow-up was 4.45 years (1 to 11). Results. The prevalence of hypertension, diabetes, and stroke was significantly higher in the fracture group and dyslipidemia in the controls. Both crude and adjusted hazard ratios (HR) for the rate of mortality in the fracture group were > 2 (crude HR 2.03, 95% confidence interval (CI) 1.91 to 2.17, p < 0.001; adjusted HR 2.07, 95% CI 1.94 to 2.21, p < 0.001). The HRs were also > 2 for both men and women, and for both those aged ≥ 50 years and < 50 years. However, for those aged < 50 years, they were insignificant. The rates of mortality due to all 11 major causes of death classified following Korean standard classification of diseases were significantly higher in the fracture group compared with the control group, except those in the mental and behavioral disorders category. Conclusion. The rate of mortality in the fracture group was significantly higher than in the control group up to 11 years after the surgery. The rate of death due to almost every major cause was significantly higher in the fracture group compared with the control group. Cite this article: Bone Joint J 2018;100-B:436–42


The Journal of Bone & Joint Surgery British Volume
Vol. 83-B, Issue 3 | Pages 414 - 418
1 Apr 2001
Clark DI Ahmed AB Baxendale BR Moran CG

In a prospective, controlled study, we measured the effect on cardiac output of the introduction of methylmethacrylate during hemiarthroplasty for displaced fractures of the femoral neck. We treated 20 elderly patients who were similar in age, height, weight and preoperative left ventricular function with either cemented or uncemented hemiarthroplasty. Using a transoesophageal Doppler probe, we measured cardiac output before incision and at six stages of the procedure: during the surgical approach, reaming and lavage of the femoral canal, the introduction of cement, the insertion of the prosthesis, and in reduction and closure. We found that before the cement was introduced, there was no difference in stroke volume or cardiac output (p > 0.25). Cementation produced a transient but significant reduction in cardiac output of 33% (p < 0.01) and a reduction in stroke volume of 44% (p < 0.02). The introduction of cement did not affect the heart rate or mean arterial pressure. There was no significant difference in cardiac function on insertion of the prosthesis. Standard non-invasive haemodynamic monitoring did not detect the cardiovascular changes which may account for the sudden deaths that sometimes occur during cemented hemiarthroplasty. The fall in stroke volume and cardiac output may be caused by embolism occurring during cementation, but there was no similar fall during reaming or insertion of the prosthesis


Bone & Joint Research
Vol. 5, Issue 9 | Pages 393 - 402
1 Sep 2016
Yang Z Liu H Li D Xie X Qin T Ma J Kang P

Objectives. The primary purpose of this meta-analysis was to determine whether statin usage could reduce the risk of glucocorticoid-related osteonecrosis in animal models. Methods. A systematic literature search up to May 2015 was carried out using the PubMed, Ovid, EBM reviews, ISI Web of Science, EBSCO, CBM, CNKI databases with the term and boolean operators: statins and osteonecrosis in all fields. Risk ratio (RR), as the risk estimate of specific outcome, was calculated along with 95% confidence intervals (CI). The methodological quality of individual studies was assessed using a quantitative tool based on the updated Stroke Therapy Academic Industry Roundtable (STAIR) recommendations. Results. A total of 11 eligible studies were included according to predetermined criteria. The pooled data demonstrated that animals with statin usage, either alone or combined with other treatments, were at a decreased risk of developing glucocorticoid-related osteonecrosis (RR = 2.06, 95% confidence interval (CI) 1.71 to 2.50). Moreover, subgroup analysis revealed that compared with statins alone, statins combined with other treatments significantly decreased the risk of osteonecrosis (RR = 1.23, 95% CI 1.02 to 1.47). However, we could find no significant risk difference for different gender, or for different time points. Conclusions. The present study suggests that statins combined with other treatments are efficient in preventing the development of glucocorticoid-related osteonecrosis in animals. These results might shed light on clinical practice when glucocorticoids are prescribed, and could be further investigated in high-quality clinical trials. Cite this article: Z. Yang, H. Liu, D. Li, X. Xie, T. Qin, J. Ma, P. Kang. The efficacy of statins in preventing glucocorticoid-related osteonecrosis in animal models: A meta-analysis. Bone Joint Res 2016;5:393–402. DOI: 10.1302/2046-3758.59.2000500


Bone & Joint Open
Vol. 5, Issue 1 | Pages 28 - 36
18 Jan 2024
Selmene MA Moreau PE Zaraa M Upex P Jouffroy P Riouallon G

Aims

Post-traumatic periprosthetic acetabular fractures are rare but serious. Few studies carried out on small cohorts have reported them in the literature. The aim of this work is to describe the specific characteristics of post-traumatic periprosthetic acetabular fractures, and the outcome of their surgical treatment in terms of function and complications.

Methods

Patients with this type of fracture were identified retrospectively over a period of six years (January 2016 to December 2021). The following data were collected: demographic characteristics, date of insertion of the prosthesis, details of the intervention, date of the trauma, characteristics of the fracture, and type of treatment. Functional results were assessed with the Harris Hip Score (HHS). Data concerning complications of treatment were collected.


The Bone & Joint Journal
Vol. 105-B, Issue 2 | Pages 135 - 139
1 Feb 2023
Karczewski D Schönnagel L Hipfl C Akgün D Hardt S

Aims

Periprosthetic joint infection (PJI) in total hip arthroplasty in the elderly may occur but has been subject to limited investigation. This study analyzed infection characteristics, surgical outcomes, and perioperative complications of octogenarians undergoing treatment for PJI in a single university-based institution.

Methods

We identified 33 patients who underwent treatment for PJIs of the hip between January 2010 and December 2019 using our institutional joint registry. Mean age was 82 years (80 to 90), with 19 females (57%) and a mean BMI of 26 kg/m2 (17 to 41). Mean American Society of Anesthesiologists (ASA) grade was 3 (1 to 4) and mean Charlson Comorbidity Index was 6 (4 to 10). Leading pathogens included coagulase-negative Staphylococci (45%) and Enterococcus faecalis (9%). Two-stage exchange was performed in 30 joints and permanent resection arthroplasty in three. Kaplan-Meier survivorship analyses were performed. Mean follow-up was five years (3 to 7).


Bone & Joint Open
Vol. 4, Issue 8 | Pages 559 - 566
1 Aug 2023
Hillier DI Petrie MJ Harrison TP Salih S Gordon A Buckley SC Kerry RM Hamer A

Aims

The burden of revision total hip arthroplasty (rTHA) continues to grow. The surgery is complex and associated with significant costs. Regional rTHA networks have been proposed to improve outcomes and to reduce re-revisions, and therefore costs. The aim of this study was to accurately quantify the cost and reimbursement for a rTHA service, and to assess the financial impact of case complexity at a tertiary referral centre within the NHS.

Methods

A retrospective analysis of all revision hip procedures was performed at this centre over two consecutive financial years (2018 to 2020). Cases were classified according to the Revision Hip Complexity Classification (RHCC) and whether they were infected or non-infected. Patients with an American Society of Anesthesiologists (ASA) grade ≥ III or BMI ≥ 40 kg/m2 are considered “high risk” by the RHCC. Costs were calculated using the Patient Level Information and Costing System (PLICS), and remuneration based on Healthcare Resource Groups (HRG) data. The primary outcome was the financial difference between tariff and cost per patient episode.


Bone & Joint Open
Vol. 4, Issue 8 | Pages 628 - 635
22 Aug 2023
Hedlundh U Karlsson J Sernert N Haag L Movin T Papadogiannakis N Kartus J

Aims

A revision for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) has a major effect on the patient’s quality of life, including walking capacity. The objective of this case control study was to investigate the histological and ultrastructural changes to the gluteus medius tendon (GMED) in patients revised due to a PJI, and to compare it with revision THAs without infection performed using the same lateral approach.

Methods

A group of eight patients revised due to a PJI with a previous lateral approach was compared with a group of 21 revised THAs without infection, performed using the same approach. The primary variables of the study were the fibril diameter, as seen in transmission electron microscopy (TEM), and the total degeneration score (TDS), as seen under the light microscope. An analysis of bacteriology, classification of infection, and antibiotic treatment was also performed.


Bone & Joint Open
Vol. 4, Issue 5 | Pages 329 - 337
8 May 2023
Khan AQ Chowdhry M Sherwani MKA McPherson EJ

Aims

Total hip arthroplasty (THA) is considered the preferred treatment for displaced proximal femoral neck fractures. However, in many countries this option is economically unviable. To improve outcomes in financially disadvantaged populations, we studied the technique of concomitant valgus hip osteotomy and operative fixation (VOOF). This prospective serial study compares two treatment groups: VOOF versus operative fixation alone with cannulated compression screws (CCSs).

Methods

In the first series, 98 hip fixation procedures were performed using CCS. After fluoroscopic reduction of the fracture, three CCSs were placed. In the second series, 105 VOOF procedures were performed using a closing wedge intertrochanteric osteotomy with a compression lag screw and lateral femoral plate. The alignment goal was to create a modified Pauwel’s fracture angle of 30°. After fluoroscopic reduction of fracture, lag screw was placed to achieve the calculated correction angle, followed by inter-trochanteric osteotomy and placement of barrel plate. Patients were followed for a minimum of two years.


The Bone & Joint Journal
Vol. 104-B, Issue 5 | Pages 598 - 603
1 May 2022
Siljander MP Gausden EB Wooster BM Karczewski D Sierra RJ Trousdale RT Abdel MP

Aims

The aim of this study was to evaluate the incidence of liner malseating in two commonly used dual-mobility (DM) designs. Secondary aims included determining the risk of dislocation, survival, and clinical outcomes.

Methods

We retrospectively identified 256 primary total hip arthroplasties (THAs) that included a DM component (144 Stryker MDM and 112 Zimmer-Biomet G7) in 233 patients, performed between January 2012 and December 2019. Postoperative radiographs were reviewed independently for malseating of the liner by five reviewers. The mean age of the patients at the time of THA was 66 years (18 to 93), 166 (65%) were female, and the mean BMI was 30 kg/m2 (17 to 57). The mean follow-up was 3.5 years (2.0 to 9.2).


The Bone & Joint Journal
Vol. 104-B, Issue 2 | Pages 212 - 220
1 Feb 2022
Fishley WG Selvaratnam V Whitehouse SL Kassam AM Petheram TG

Aims

Femoral cement-in-cement revision is a well described technique to reduce morbidity and complications in hip revision surgery. Traditional techniques for septic revision of hip arthroplasty necessitate removal of all bone cement from the femur. In our two centres, we have been using a cement-in-cement technique, leaving the distal femoral bone cement in selected patients for septic hip revision surgery, both for single and the first of two-stage revision procedures. A prerequisite for adoption of this technique is that the surgeon considers the cement mantle to be intimately fixed to bone without an intervening membrane between cement and host bone. We aim to report our experience for this technique.

Methods

We have analyzed patients undergoing this cement-in-cement technique for femoral revision in infection, and present a consecutive series of 89 patients. Follow-up was undertaken at a mean of 56.5 months (24.0 to 134.7) for the surviving cases.


The Bone & Joint Journal
Vol. 103-B, Issue 7 Supple B | Pages 84 - 90
1 Jul 2021
Yang J Olsen AS Serino J Terhune EB DeBenedetti A Della Valle CJ

Aims

The proportion of arthroplasties performed in the ambulatory setting has increased considerably. However, there are concerns whether same-day discharge may increase the risk of complications. The aim of this study was to compare 90-day outcomes between inpatient arthroplasties and outpatient arthroplasties performed at an ambulatory surgery centre (ASC), and determine whether there is a learning curve associated with performing athroplasties in an ASC.

Methods

Among a single-surgeon cohort of 970 patients who underwent arthroplasty at an ASC, 854 (88.0%) were matched one-to-one with inpatients based on age, sex, American Society of Anesthesiologists (ASA) grade, BMI, and procedure (105 could not be adequately matched and 11 lacked 90-day follow-up). The cohort included 281 total hip arthroplasties (THAs) (32.9%), 267 unicompartmental knee arthroplasties (31.3%), 242 primary total knee arthroplasties (TKAs) (28.3%), 60 hip resurfacings (7.0%), two revision THAs (0.3%), and two revision TKAs (0.3%). Outcomes included readmissions, reoperations, visits to the emergency department, unplanned clinic visits, and complications.


The Bone & Joint Journal
Vol. 103-B, Issue 7 | Pages 1197 - 1205
1 Jul 2021
Magill P Hill JC Bryce L Martin U Dorman A Hogg R Campbell C Gardner E McFarland M Bell J Benson G Beverland D

Aims

A typical pattern of blood loss associated with total hip arthroplasty (THA) is 200 ml intraoperatively and 1.3 l in the first 48 postoperative hours. Tranexamic acid (TXA) is most commonly given as a single preoperative dose only and is often withheld from patients with a history of thromboembolic disease as they are perceived to be “high-risk” with respect to postoperative venous thromboembolism (VTE). The TRanexamic ACid for 24 hours trial (TRAC-24) aimed to identify if an additional 24-hour postoperative TXA regime could further reduce blood loss beyond a once-only dose at the time of surgery, without excluding these high-risk patients.

Methods

TRAC-24 was a prospective, phase IV, single centre, open label, parallel group, randomized controlled trial (RCT) involving patients undergoing primary unilateral elective THA. The primary outcome measure was the indirect calculated blood loss (IBL) at 48 hours. The patients were randomized into three groups. Group 1 received 1 g intravenous (IV) TXA at the time of surgery and an additional oral regime for 24 hours postoperatively, group 2 only received the intraoperative dose, and group 3 did not receive any TXA.


Bone & Joint Research
Vol. 10, Issue 6 | Pages 354 - 362
1 Jun 2021
Luo Y Zhao X Yang Z Yeersheng R Kang P

Aims

The purpose of this study was to examine the efficacy and safety of carbazochrome sodium sulfonate (CSS) combined with tranexamic acid (TXA) on blood loss and inflammatory responses after primary total hip arthroplasty (THA), and to investigate the influence of different administration methods of CSS on perioperative blood loss during THA.

Methods

This study is a randomized controlled trial involving 200 patients undergoing primary unilateral THA. A total of 200 patients treated with intravenous TXA were randomly assigned to group A (combined intravenous and topical CSS), group B (topical CSS), group C (intravenous CSS), or group D (placebo).


Bone & Joint Open
Vol. 2, Issue 8 | Pages 611 - 617
10 Aug 2021
Kubik JF Bornes TD Klinger CE Dyke JP Helfet DL

Aims

Surgical treatment of young femoral neck fractures often requires an open approach to achieve an anatomical reduction. The application of a calcar plate has recently been described to aid in femoral neck fracture reduction and to augment fixation. However, application of a plate may potentially compromise the regional vascularity of the femoral head and neck. The purpose of this study was to investigate the effect of calcar femoral neck plating on the vascularity of the femoral head and neck.

Methods

A Hueter approach and capsulotomy were performed bilaterally in six cadaveric hips. In the experimental group, a one-third tubular plate was secured to the inferomedial femoral neck at 6:00 on the clockface. The contralateral hip served as a control with surgical approach and capsulotomy without fixation. Pre- and post-contrast MRI was then performed to quantify signal intensity in the femoral head and neck. Qualitative assessment of the terminal arterial branches to the femoral head, specifically the inferior retinacular artery (IRA), was also performed.


The Bone & Joint Journal
Vol. 103-B, Issue 2 | Pages 309 - 320
1 Feb 2021
Powell-Bowns MFR Oag E Ng N Pandit H Moran M Patton JT Clement ND Scott CEH

Aims

The aim of this study was to determine whether fixation, as opposed to revision arthroplasty, can be safely used to treat reducible Vancouver B type fractures in association with a cemented collarless polished tapered femoral stem (the Exeter).

Methods

This retrospective cohort study assessed 152 operatively managed consecutive unilateral Vancouver B fractures involving Exeter stems; 130 were managed with open reduction and internal fixation (ORIF) and 22 with revision arthroplasty. Mean follow-up was 6.5 years (SD 2.6; 3.2 to 12.1). The primary outcome measure was revision of at least one component. Kaplan–Meier survival analysis was performed. Regression analysis was used to identify risk factors for revision following ORIF. Secondary outcomes included any reoperation, complications, blood transfusion, length of hospital stay, and mortality.


The Bone & Joint Journal
Vol. 101-B, Issue 6_Supple_B | Pages 77 - 83
1 Jun 2019
Roberts HJ Tsay EL Grace TR Vail TP Ward DT

Aims

Increasingly, patients with bilateral hip arthritis wish to undergo staged total hip arthroplasty (THA). With the rise in demand for arthroplasty, perioperative risk assessment and counselling is crucial for shared decision making. However, it is unknown if complications that occur after a unilateral hip arthroplasty predict complications following surgery of the contralateral hip.

Patients and Methods

We used nationwide linked discharge data from the Healthcare Cost and Utilization Project between 2005 and 2014 to analyze the incidence and recurrence of complications following the first- and second-stage operations in staged bilateral total hip arthroplasty (BTHAs). Complications included perioperative medical adverse events within 30 to 60 days, and infection and mechanical complications within one year. Conditional probabilities and odds ratios (ORs) were calculated to determine whether experiencing a complication after the first stage of surgery increased the risk of developing the same complication after the second stage.


Bone & Joint Research
Vol. 9, Issue 8 | Pages 468 - 476
1 Aug 2020
Parsons NR Costa ML Achten J Griffin XL

Aims

To assess the variation in pre-fracture quality of life (QoL) within the UK hip fracture population, and quantify the nature and strength of associations between QoL and other routinely collected patient characteristics and treatment choices.

Methods

The World Hip Trauma Evaluation (WHiTE) study, an observational cohort study of UK hip fracture patients, collects a range of routine data and a health-related QoL score (EuroQol five-dimension questionnaire (EQ-5D)). Pre-fracture QoL data are summarized and statistical models fitted to understand associations between QoL, patient characteristics, fracture types, and operations.


The Bone & Joint Journal
Vol. 101-B, Issue 5 | Pages 547 - 551
1 May 2019
Malik AT Li M Scharschmidt TJ Khan SN

Aims

The aim of this study was to investigate the differences in 30-day outcomes between patients undergoing revision for an infected total hip arthroplasty (THA) compared with an aseptic revision THA.

Patients and Methods

This was a retrospective review of prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database, between 2012 and 2017, using Current Procedural Terminology (CPT) codes for patients undergoing a revision THA (27134, 27137, 27138). International Classification of Diseases Ninth Revision/Tenth Revision (ICD-9-CM, ICD-10-CM) diagnosis codes for infection of an implant or device were used to identify patients undergoing an infected revision THA. CPT-27132 coupled with ICD-9-CM/ICD-10-CM codes for infection were used to identify patients undergoing a two-stage revision. A total of 13 556 patients were included; 1606 (11.8%) underwent a revision THA due to infection and there were 11 951 (88.2%) aseptic revisions.


The Bone & Joint Journal
Vol. 101-B, Issue 5 | Pages 540 - 546
1 May 2019
Juneau D Grammatopoulos G Alzahrani A Thornhill R Inacio JR Dick A Vogel KI Dobransky J Beaulé PE Dwivedi G

Aims

Cardiac magnetic resonance (CMR) was used to assess whether cardiac function or tissue composition was affected in patients with well-functioning metal-on-metal hip resurfacing arthroplasties (MoMHRA) when compared with a group of controls, and to assess if metal ion levels correlated with any of the functional or structural parameters studied.

Patients and Methods

In all, 30 participants with no significant cardiac history were enrolled: 20 patients with well-functioning MoMHRA at mean follow-up of 8.3 years post-procedure (ten unilateral, ten bilateral; 17 men, three women) and a case-matched control group of ten non-MoM total hip arthroplasty patients (six men, four women). The mean age of the whole cohort (study group and controls) at the time of surgery was 50.6 years (41.0 to 64.0). Serum levels of cobalt and chromium were measured, and all patients underwent CMR imaging, including cine, T2* measurements, T1 and T2 mapping, late gadolinium enhancement, and strain measurements.


The Bone & Joint Journal
Vol. 101-B, Issue 12 | Pages 1585 - 1592
1 Dec 2019
Logishetty K Rudran B Cobb JP

Aims

Arthroplasty skills need to be acquired safely during training, yet operative experience is increasingly hard to acquire by trainees. Virtual reality (VR) training using headsets and motion-tracked controllers can simulate complex open procedures in a fully immersive operating theatre. The present study aimed to determine if trainees trained using VR perform better than those using conventional preparation for performing total hip arthroplasty (THA).

Patients and Methods

A total of 24 surgical trainees (seven female, 17 male; mean age 29 years (28 to 31)) volunteered to participate in this observer-blinded 1:1 randomized controlled trial. They had no prior experience of anterior approach THA. Of these 24 trainees, 12 completed a six-week VR training programme in a simulation laboratory, while the other 12 received only conventional preparatory materials for learning THA. All trainees then performed a cadaveric THA, assessed independently by two hip surgeons. The primary outcome was technical and non-technical surgical performance measured by a THA-specific procedure-based assessment (PBA). Secondary outcomes were step completion measured by a task-specific checklist, error in acetabular component orientation, and procedure duration.


The Bone & Joint Journal
Vol. 101-B, Issue 6_Supple_B | Pages 51 - 56
1 Jun 2019
Nowak LL Schemitsch EH

Aims

The aim of this study was to assess the influence of operating time on 30-day complications following total hip arthroplasty (THA).

Patients and Methods

We identified patients aged 18 years and older who underwent THA between 2006 and 2016 from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database. We identified 131 361 patients, with a mean age of 65 years (sd 12), who underwent THA. We used multivariable regression to determine if the rate of complications and re-admissions was related to the operating time, while adjusting for relevant covariables.


Aims

The aim of this study was to examine the efficacy and safety of multiple boluses of intravenous (IV) tranexamic acid (TXA) on the hidden blood loss (HBL) and inflammatory response following primary total hip arthroplasty (THA).

Patients and Methods

A total of 150 patients were allocated randomly to receive a single bolus of 20 mg/kg IV TXA before the incision (group A), a single bolus followed by a second bolus of 1 g IV-TXA three hours later (group B) or a single bolus followed by two boluses of 1 g IV-TXA three and six hours later (group C). All patients were treated using a standard peri-operative enhanced recovery protocol. Primary outcomes were HBL and the level of haemoglobin (Hb) as well as the levels of C-reactive protein (CRP) and interleukin-6 (IL-6) as markers of inflammation. Secondary outcomes included the length of stay in hospital and the incidence of venous thromboembolism (VTE).


The Bone & Joint Journal
Vol. 100-B, Issue 7 | Pages 915 - 922
1 Jul 2018
Joice M Vasileiadis GI Amanatullah DF

Aims

The aim of this study was to assess the efficacy of non-selective and selective non-steroidal anti-inflammatory drugs (NSAIDs) in preventing heterotopic ossification (HO) after total hip arthroplasty (THA).

Methods

A thorough and systematic literature search was conducted and 29 studies were found that met inclusion criteria. Data were extracted and statistical analysis was carried out generating forest plots.


Bone & Joint Research
Vol. 5, Issue 11 | Pages 531 - 537
1 Nov 2016
Burgo FJ Mengelle DE Ozols A Fernandez C Autorino CM

Objectives

Studies reporting specifically on squeaking in total hip arthroplasty have focused on cementless, and not on hybrid, fixation. We hypothesised that the cement mantle of the femur might have a damping effect on the sound transmitted through the metal stem. The objective of this study was to test the effect of cement on sound propagation along different stem designs and under different fixation conditions.

Methods

An in vitro model for sound detection, composed of a mechanical suspension structure and a sound-registering electronic assembly, was designed. A pulse of sound in the audible range was propagated along bare stems and stems implanted in cadaveric bone femurs with and without cement. Two stems of different alloy and geometry were compared.


The Bone & Joint Journal
Vol. 98-B, Issue 8 | Pages 1027 - 1035
1 Aug 2016
Pereira LC Kerr J Jolles BM

Aims

Using a systematic review, we investigated whether there is an increased risk of post-operative infection in patients who have received an intra-articular corticosteroid injection to the hip for osteoarthritis prior to total hip arthroplasty (THA).

Methods

Studies dealing with an intra-articular corticosteroid injection to the hip and infection following subsequent THA were identified from databases for the period between 1990 to 2013. Retrieved articles were independently assessed for their methodological quality.


The Bone & Joint Journal
Vol. 96-B, Issue 11 | Pages 1464 - 1471
1 Nov 2014
Lindberg-Larsen M Jørgensen CC Hansen TB Solgaard S Kehlet H

Data on early morbidity and complications after revision total hip replacement (THR) are limited. The aim of this nationwide study was to describe and quantify early morbidity after aseptic revision THR and relate the morbidity to the extent of the revision surgical procedure. We analysed all aseptic revision THRs from 1st October 2009 to 30th September 2011 using the Danish National Patient Registry, with additional information from the Danish Hip Arthroplasty Registry. There were 1553 procedures (1490 patients) performed in 40 centres and we divided them into total revisions, acetabular component revisions, femoral stem revisions and partial revisions. The mean age of the patients was 70.4 years (25 to 98) and the median hospital stay was five days (interquartile range 3 to 7). Within 90 days of surgery, the readmission rate was 18.3%, mortality rate 1.4%, re-operation rate 6.1%, dislocation rate 7.0% and infection rate 3.0%. There were no differences in these outcomes between high- and low-volume centres. Of all readmissions, 255 (63.9%) were due to ‘surgical’ complications versus 144 (36.1%) ‘medical’ complications. Importantly, we found no differences in early morbidity across the surgical subgroups, despite major differences in the extent and complexity of operations. However, dislocations and the resulting morbidity represent the major challenge for improvement in aseptic revision THR.

Cite this article: Bone Joint J 2014; 96-B:1464–71.


The Bone & Joint Journal
Vol. 96-B, Issue 11_Supple_A | Pages 27 - 31
1 Nov 2014
Kraay MJ Bigach SD

Degenerative problems of the hip in patients with childhood and adult onset neuromuscular disorders can be challenging to treat. Many orthopaedic surgeons are reluctant to recommend total hip replacement (THR) for patients with underlying neuromuscular disorders due to the perceived increased risks of dislocation, implant loosening, and lack of information about the functional outcomes and potential benefits of these procedures in these patients. Modular femoral components and alternative bearings which facilitate the use of large femoral heads, constrained acetabular components and perhaps more importantly, a better understanding about the complications and outcomes of THR in the patient with neuromuscular disorders, make this option viable. This paper will review the current literature and our experience with THR in the more frequently encountered neuromuscular disorders.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):27–31.


The Bone & Joint Journal
Vol. 97-B, Issue 12 | Pages 1623 - 1627
1 Dec 2015
Mounsey EJ Williams DH Howell JR Hubble MJ

Revision of a cemented hemiarthroplasty of the hip may be a hazardous procedure with high rates of intra-operative complications. Removing well-fixed cement is time consuming and risks damaging already weak bone or perforating the femoral shaft. The cement-in-cement method avoids removal of intact cement and has shown good results when used for revision total hip arthroplasty (THA). The use of this technique for the revision of a hemiarthroplasty to THA has not been previously reported.

A total of 28 consecutive hemiarthroplasties (in 28 patients) were revised to a THA using an Exeter stem and the cement-in-cement technique. There were four men and 24 women; their mean age was 80 years (35 to 93). Clinical and radiographic data, as well as operative notes, were collected prospectively and no patient was lost to follow-up.

Four patients died within two years of surgery. The mean follow up of the remainder was 70 months (25 to 124). Intra-operatively there was one proximal perforation, one crack of the femoral calcar and one acetabular fracture. No femoral components have required subsequent revision for aseptic loosening or are radiologically loose.

Four patients with late complications (14%) have since undergone surgery (two for a peri-prosthetic fracture, and one each for deep infection and recurrent dislocation) resulting in an overall major rate of complication of 35.7%.

The cement-in-cement technique provides reliable femoral fixation in this elderly population and may reduce operating time and rates of complication.

Cite this article: Bone Joint J 2015;97-B:1623–7.


The Bone & Joint Journal
Vol. 97-B, Issue 5 | Pages 595 - 602
1 May 2015
McCalden RW Korczak A Somerville L Yuan X Naudie DD

This was a randomised controlled trial studying the safety of a new short metaphyseal fixation (SMF) stem. We hypothesised that it would have similar early clinical results and micromovement to those of a standard-length tapered Synergy metaphyseal fixation stem. Using radiostereometric analysis (RSA) we compared the two stems in 43 patients. A short metaphyseal fixation stem was used in 22 patients and a Synergy stem in 21 patients. No difference was found in the clinical outcomes pre- or post-operatively between groups. RSA showed no significant differences two years post-operatively in mean micromovement between the two stems (except for varus/valgus tilt at p = 0.05) (subsidence 0.94 mm (sd 1.71) vs 0.32 mm (sd 0.45), p = 0.66; rotation 0.96° (sd 1.49) vs 1.41° (sd 2.95), p = 0.88; and total migration 1.09 mm (sd 1.74) vs 0.73 mm (sd 0.72), p = 0.51). A few stems (four SMF and three Synergy) had initial migration > 1.0 mm but stabilised by three to six months, with the exception of one SMF stem which required revision three years post-operatively. For most stems, total micromovement was very low at two years (subsidence < 0.5 mm, rotation < 1.0°, total migration < 0.5 mm), which was consistent with osseous ingrowth. The small sample makes it difficult to confirm the universal applicability of or elucidate the potential contraindications to the use of this particular new design of stem.

Cite this article: Bone Joint J 2015; 97-B:595–602.


The Bone & Joint Journal
Vol. 97-B, Issue 3 | Pages 312 - 317
1 Mar 2015
Amanatullah DF Howard JL Siman H Trousdale RT Mabry TM Berry DJ

Revision total hip arthroplasty (THA) is challenging when there is severe loss of bone in the proximal femur. The purpose of this study was to evaluate the clinical and radiographic outcomes of revision THA in patients with severe proximal femoral bone loss treated with a fluted, tapered, modular femoral component. Between January 1998 and December 2004, 92 revision THAs were performed in 92 patients using a single fluted, tapered, modular femoral stem design. Pre-operative diagnoses included aseptic loosening, infection and peri-prosthetic fracture. Bone loss was categorised pre-operatively as Paprosky types III-IV, or Vancouver B3 in patients with a peri-prosthetic fracture. The mean clinical follow-up was 6.4 years (2 to 12). A total of 47 patients had peri-operative complications, 27 of whom required further surgery. However, most of these further operations involved retention of a well-fixed femoral stem, and 88/92 femoral components (97%) remained in situ. Of the four components requiring revision, three were revised for infection and were well fixed at the time of revision; only one (1%) was revised for aseptic loosening. The most common complications were post-operative instability (17 hips, 19%) and intra-operative femoral fracture during insertion of the stem (11 hips, 12%). Diaphyseal stress shielding was noted in 20 hips (22%). There were no fractures of the femoral component. At the final follow-up 78% of patients had minimal or no pain.

Revision THA in patients with extensive proximal femoral bone loss using the Link MP fluted, tapered, modular stem led to a high rate of osseointegration of the stem at mid-term follow-up.

Cite this article: Bone Joint J 2015; 97-B:312–17.


The Bone & Joint Journal
Vol. 96-B, Issue 9 | Pages 1178 - 1184
1 Sep 2014
Tarrant SM Hardy BM Byth PL Brown TL Attia J Balogh ZJ

There is a high rate of mortality in elderly patients who sustain a fracture of the hip. We aimed to determine the rate of preventable mortality and errors during the management of these patients. A 12 month prospective study was performed on patients aged > 65 years who had sustained a fracture of the hip. This was conducted at a Level 1 Trauma Centre with no orthogeriatric service. A multidisciplinary review of the medical records by four specialists was performed to analyse errors of management and elements of preventable mortality. During 2011, there were 437 patients aged > 65 years admitted with a fracture of the hip (85 years (66 to 99)) and 20 died while in hospital (86.3 years (67 to 96)). A total of 152 errors were identified in the 80 individual reviews of the 20 deaths. A total of 99 errors (65%) were thought to have at least a moderate effect on death; 45 reviews considering death (57%) were thought to have potentially been preventable. Agreement between the panel of reviewers on the preventability of death was fair. A larger-scale assessment of preventable mortality in elderly patients who sustain a fracture of the hip is required. Multidisciplinary review panels could be considered as part of the quality assurance process in the management of these patients.

Cite this article: Bone Joint J 2014;96-B:1178–84.


The Bone & Joint Journal
Vol. 96-B, Issue 9 | Pages 1207 - 1213
1 Sep 2014
te Stroet MAJ Bronsema E Rijnen WHC Gardeniers JWM Schreurs BW

In this retrospective study, we investigated the results of revision total hip replacement (THR) using a cemented long-stemmed Exeter femoral component, with a minimum length of 205 mm in patients with extensive femoral bone defects. The study included 37 consecutive patients with a mean age of 76 years (39 to 93) and a mean follow-up of nine years (5 to 16). A total of 26 patients (70%) had a pre-operative Endo-Klinik score of 3 or 4. Impaction bone grafting was used in 24 patients (65%). At the time of evaluation, 22 patients (59%) were still alive and were evaluated clinically and radiologically. A total of 14 patients died during follow-up and their data were included until the time of their death. One reconstruction failed after five years and five months owing to recurrent dislocation: the hip was converted to an excision arthroplasty. Intra-operative fractures or fissures were encountered in nine patients (24%), but none occurred during impaction of the bone graft. Post-operative peri-prosthetic fractures occurred in two patients (5%); both were treated with plate fixation. At nine years, survival with the endpoint of all-cause re-revision was 96.3% (95% CI 76.4 to 99.5); including re-operations for any reason, it was 80.7% (95% CI 56.3 to 92.3%). There were no re-revisions for aseptic loosening.

The survival of long stem cemented femoral components following revision THR is satisfactory in a fragile population with extensive femoral defects.

Cite this article: Bone Joint J 2014; 96-B:1207–13.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 8 | Pages 993 - 996
1 Aug 2006
Kesteris U Aspenberg P

During revision total hip replacement using morcellised compacted bone allograft, 16 patients were randomised to receive a graft which had been rinsed in either an ibandronate solution or in saline. Patients were assessed by dual energy x-ray absorptiometry after operation and at 3, 6, 12 and 24 months. A region of interest between the tip of the femoral stem and the distal plastic plug was chosen to measure the changes in bone density over time. The study was double-blinded. In all the control patients the bone density decreased during the first three months and then remained constant at this lower level. A large proportion of the mass of the bone graft was lost. In contrast, all patients with grafts treated with bisphosphonate showed a slight increase in bone density. The difference between the groups was highly significant at all points in time.

We conclude that rinsing the graft in a bisphosphonate solution prevents its resorption and may therefore reduce the risk of mechanical failure. The treatment is simple, inexpensive, and appears virtually free of risk.


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 2 | Pages 172 - 177
1 Feb 2011
Pedersen AB Baron JA Overgaard S Johnsen SP

We evaluated the short-term of 0 to 90 days and the longer term, up to 12.7 years, mortality for patients undergoing primary total hip replacement (THR) in Denmark in comparison to the general population. Through the Danish Hip Arthroplasty Registry we identified all primary THRs undertaken for osteoarthritis between 1 January 1995 and 31 December 2006. Each patient (n = 44 558) was matched at the time of surgery with three people from the general population (n = 133 674). We estimated mortality rates and mortality rate ratios with 95% confidence intervals for THR patients compared with the general population. There was a one-month period of increased mortality immediately after surgery among THR patients, but overall short-term mortality (0 to 90 days) was significantly lower (mortality rate ratio 0.8; 95% confidence interval 0.7 to 0.9). However, THR surgery was associated with increased short-term mortality in subjects under 60 years old, and among THR patients without comorbidity. Long-term mortality was lower among THR patients than in controls (mortality rate ratio 0.7; 95% confidence interval 0.7 to 0.7).

Overall, THR was associated with lower short- and long-term mortality among patients with osteoarthritis. Younger patients and patients without comorbidity before surgery may also experience increased mortality after THR surgery, although the absolute risk of death is small.


The Bone & Joint Journal
Vol. 95-B, Issue 4 | Pages 459 - 466
1 Apr 2013
Fisher WD Agnelli G George DJ Kakkar AK Lassen MR Mismetti P Mouret P Turpie AGG

There is currently limited information available on the benefits and risks of extended thromboprophylaxis after hip fracture surgery. SAVE-HIP3 was a randomised, double-blind study conducted to evaluate the efficacy and safety of extended thromboprophylaxis with the ultra-low molecular-weight heparin semuloparin compared with placebo in patients undergoing hip fracture surgery. After a seven- to ten-day open-label run-in phase with semuloparin (20 mg once daily subcutaneously, initiated post-operatively), patients were randomised to once-daily semuloparin (20 mg subcutaneously) or placebo for 19 to 23 additional days. The primary efficacy endpoint was a composite of any venous thromboembolism (VTE; any deep-vein thrombosis and non-fatal pulmonary embolism) or all-cause death until day 24 of the double-blind period. Safety parameters included major and clinically relevant non-major bleeding, laboratory data, and treatment-emergent adverse events (TEAEs). Extended thromboprophylaxis with semuloparin demonstrated a relative risk reduction of 79% in the rate of any VTE or all-cause death compared with placebo (3.9% vs 18.6%, respectively; odds ratio 0.18 (95% confidence interval 0.07 to 0.45), p < 0.001). Two patients in the semuloparin group and none in the placebo group experienced clinically relevant bleeding. TEAE rates were similar in both groups. In conclusion, the SAVE-HIP3 study results demonstrate that patients undergoing hip fracture surgery benefit from extended thromboprophylaxis.

Cite this article: Bone Joint J 2013;95-B:459–66.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 9 | Pages 1149 - 1157
1 Sep 2006
Khoo PPC Michalak KA Yates PJ Megson SM Day RE Wood DJ

Iontophoresis is a novel technique which may be used to facilitate the movement of antibiotics into the substance of bone using an electrical potential applied externally. We have examined the rate of early infection in allografts following application of this technique in clinical practice. A total of 31 patients undergoing revision arthroplasty or surgery for limb salvage received 34 iontophoresed sequential allografts, of which 26 survived for a minimum of two years. The mean serum antibiotic levels after operation were low (gentamicin 0.37 mg/l (0.2 to 0.5); flucloxacillin 1 mg/l (0 to 1) and the levels in the drains were high (gentamicin 40 mg/l (2.5 to 131); flucloxacillin 17 mg/l (1 to 43). There were no early deep infections. Two late infections were presumed to be haemotogenous; 28 of the 34 allografts were retained. In 12 patients with pre-existing proven infection further infection has not occurred at a mean follow-up of 51 months (24 to 82).


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 12 | Pages 1648 - 1653
1 Dec 2010
Cordingley R Kohan L Ben-Nissan B

The major advantage of hip resurfacing is the decreased amount of bone resection compared with a standard total hip replacement. Fracture of the femoral neck is the most common early complication and poor bone quality is a major risk factor. We undertook a prospective consecutive case control study examining the effect of bone mineral density changes in patients undergoing hip resurfacing surgery. A total of 423 patients were recruited with a mean age of 54 years (24 to 87). Recruitment for this study was dependent on pre-operative bilateral femoral bone mineral density results not being osteoporotic. The operated and non-operated hips were assessed. Bone mineral density studies were repeated over a two-year period. The results showed no significant deterioration in the bone mineral density in the superolateral region in the femoral neck, during that period.

These findings were in the presence of a markedly increased level of physical activity, as measured by the short-form 36 health survey physical function score.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 7 | Pages 929 - 934
1 Jul 2010
Pedersen AB Mehnert F Johnsen SP Sørensen HT

We have evaluated the extent to which diabetes affects the revision rate following total hip replacement (THR). Through the Danish Hip Arthroplasty Registry we identified all patients undergoing a primary THR (n = 57 575) between 1 January 1996 and 31 December 2005, of whom 3278 had diabetes. The presence of diabetes among these patients was identified through the Danish National Registry of Patients and the Danish National Drug Prescription Database. We estimated the relative risk for revision and the 95% confidence intervals for patients with diabetes compared to those without, adjusting for the confounding factors. Diabetes is associated with an increased risk of revision due to deep infection (relative risk = 1.45 (95% confidence interval 1.00 to 2.09), particularly in those with type 2 diabetes (relative risk = 1.49 (95% confidence interval 1.02 to 2.18)), those with diabetes for less than five years prior to THR (relative risk = 1.69 (95% confidence interval 1.24 to 2.32)), those with complications due to diabetes (relative risk = 2.11 (95% confidence interval 1.41 to 3.17)), and those with cardiovascular comorbidities prior to surgery (relative risk = 2.35 (95% confidence interval 1.39 to 3.98)).

Patients and surgeons should be aware of the relatively elevated risk of revision due to deep infection following THR in diabetes particularly in those with insufficient control of their glucose level.


The Journal of Bone & Joint Surgery British Volume
Vol. 89-B, Issue 7 | Pages 887 - 892
1 Jul 2007
Cohen AT Skinner JA Warwick D Brenkel I

Little is known about the efficacy of graduated compression stockings in preventing venous thromboembolism after hip surgery. We conducted a prospective, randomised single-blind study to determine whether the addition of compression stockings to fondaparinux conferred any additional benefit.

The study included 874 patients, of whom 795 could be evaluated (400 in the fondaparinux group and 395 in the fondaparinux plus compression stocking group). Fondaparinux was given post-operatively for five to nine days, either alone or combined with wearing stockings, which were worn for a mean 42 days (35 to 49).

The study outcomes were venous thromboembolism, or sudden death before day 42. Duplex ultrasonography was scheduled within a week of day 42. Safety outcomes were bleeding and death from venous thromboembolism.

The prevalence of deep-vein thrombosis was similar in the two groups 5.5% (22 of 400) in the fondaparinux group and 4.8 (19 of 395) in the fondaparinux plus stocking group (odds ratio 0.88, 95% confidence interval 0.46 to 1.65, p = 0.69). Major bleeding occurred in only one patient.

The addition of graduated compression stockings to fondaparinux appears to offer no additional benefit over the use of fondaparinux alone.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 11 | Pages 1430 - 1437
1 Nov 2006
Michalak KA Khoo PPC Yates PJ Day RE Wood DJ

Revision arthroplasty after infection can often be complicated by both extensive bone loss and a relatively high rate of re-infection. Using allograft to address the bone loss in such patients is controversial because of the perceived risk of bacterial infection from the use of avascular graft material. We describe 12 two-stage revisions for infection in which segmental allografts were loaded with antibiotics using iontophoresis, a technique using an electrical potential to drive ionised antibiotics into cortical bone.

Iontophoresis produced high levels of antibiotic in the allograft, which eluted into the surrounding tissues. We postulate that this offers protection from infection in the high-risk peri-operative period. None of the 12 patients who had two-stage revision with iontophoresed allografts had further infection after a mean period of 47 months (14 to 78).


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 10 | Pages 1303 - 1308
1 Oct 2006
Johnsen SP Sørensen HT Lucht U Søballe K Overgaard S Pedersen AB

We examined the association between patient-related factors and the risk of initial, short- and long-term implant failure after primary total hip replacement. We used data from the Danish Hip Arthroplasty Registry between 1 January 1995 and 31 December 2002, which gave us a total of 36 984 patients. Separate analyses were carried out for three follow-up periods: 0 to 30 days, 31 days to six months (short term), and six months to 8.6 years after primary total hip replacement (long term). The outcome measure was defined as time to failure, which included re-operation with open surgery for any reason.

Male gender and a high Charlson co-morbidity index score were strongly predictive for failure, irrespective of the period of follow-up. Age and diagnosis at primary total hip replacement were identified as time-dependent predictive factors of failure. During the first 30 days after primary total hip replacement, an age of 80 years or more and hip replacement undertaken as a sequela of trauma, for avascular necrosis or paediatric conditions, were associated with an increased risk of failure. However, during six months to 8.6 years after surgery, being less than 60 years old was associated with an increased risk of failure, whereas none of the diagnoses for primary total hip replacement appeared to be independent predictors.