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Bone & Joint Research
Vol. 6, Issue 4 | Pages 253 - 258
1 Apr 2017
Hsu C Lin C Jou I Wang P Lee J

Objectives

Osteoarthritis (OA) is the most common form of arthritis, affecting approximately 15% of the human population. Recently, increased concentration of nitric oxide in serum and synovial fluid in patients with OA has been observed. However, the exact role of nitric oxide in the initiation of OA has not been elucidated. The aim of the present study was to investigate the role of nitric oxide in innate immune regulation during OA initiation in rats.

Methods

Rat OA was induced by performing meniscectomy surgery while cartilage samples were collected 0, 7, and 14 days after surgery. Cartilage cytokine levels were determined by using enzyme-linked immunosorbent assay, while other proteins were assessed by using Western blot


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 116 - 116
1 Feb 2017
Lee J Hyung J Jeong H
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BACKGROUNDS

Total knee arthroplasty (TKA) using an imageless navigation is widely used in these days. Despite the usefulness of navigation-assisted TKA, there are still limitations of accuracy. From previous studies, many factors have been suggested as causes of the discordance between pre-op planning and post-op results. In Addition, Registration of reliable landmark is very important factor in navigation-assisted TKA, fundamentally. Nevertheless, current method of registration process is substantially affected by subjective preference of operators. Until now, However, there is no consensus about the optimal range of reference point. Moreover, the tolerance of imageless navigation system is still questionable. We investigated the effect of variation during the manual registration in this study. We compared the measured alignment and calculated plan of navigation system which were collected from repeated independent registration processes.

METHODS

From 7 March 2016 to 13 May 2016, 44 patients (49 knees) underwent navigation assisted TKA with Orthopilot® Aesculap system. The subject group were severe osteoarthritis patients, they have evaluated radiographically and clinically before the operation. we excluded candidates who have shown very severe mal-alignment (>20 °) and metaphyseal bowing in Pre-op radiographic evaluation. All patients were followed for postoperative long axis film that could measure the correction angle, and followed clinically for functional score. Authors executed multiple registration trials in a single case, each trial was implemented by different surgeons (Senior surgeon JHJ and trainee LJH1, LJH2). At first, Senior surgeon (JHJ) start the operation from initial approach. Standard sub-vastus approach was applied to all-patients. After the procedure of joint exposure, each participating surgeon did the examination of knee anatomy and registered optimal point of his own. It was repeated three times (J,L1,L2) via imageless navigation system. Then, we collected the information of measured limb alignments and calculated plans of tibia cutting from navigation system.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 8 - 8
1 Feb 2017
Lee H Ham D Lee J Ryu H Chang G Kim S Park Y
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Introduction

The range of motion (ROM) obtained after total knee arthroplasty (TKA) is an important measurement to evaluate the postoperative outcomes impacting other measures such as postoperative function and satisfaction. Flexion contracture is a recognized complication of TKA, which reduces ROM or stability and is a source of morbidity for patients.

Objectives

The purpose of this study was to evaluate the influence of intra-operative soft tissue release on correction of flexion contracture in navigated TKA.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_10 | Pages 34 - 34
1 May 2016
Shin Y Lee J Han S
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A matched comparison was made between femoral neck-preserving short, tapered stems (n = 50) and conventional length femoral stems (n = 50) in cementless total hip arthroplasty between January 2008 and January 2012. Patients were matched for age, sex, body mass index, height, surgical approach, and surgeon. In group A, mean preoperative HHS and WOMAC scores of 55.0 and 53.0, respectively, improved to mean postoperative scores of 98.6 and 3.3, respectively, at an average follow–up of 37.2 months. In group B, mean preoperative HHS and WOMAC scores of 53.0 and 49.5, respectively, improved to mean postoperative scores 97.8 and 4.4, respectively, at an average follow–up of 35.3 months. In addition, no significant differences in mean postoperative HHS (P = 0.168) or WOMAC scores (P = 0.158) were observed between the two groups according to the independent sample t-test. Table 1 shows two stems (4%) located in valgus (greater than 5° from neutral). The mean preoperative and postoperative HHS and WOMAC scores were similar to those of stems neutrally located in group A. All group A stems displayed bone bridging and endosteal spot welds distributed in Gruen zones 2 and 6 as evidence of bony ingrowth with no radiolucencies (Fig. 1). Two patients in group B had the slight decrease in bone density, mostly in Gruen zone 1 and 7. No radiographic evidence of osteolytic lesions, cortical hypertrophy, or acetabular fractures was detected in either group. Furthermore, no patient required revision surgery for aseptic loosening. The chi–square (Fisher's exact) test showed no significant difference between the two groups with respect to patient complications (Table 2). One patient in group A with a CCD angle of 135° had subsidence (greater than 2 mm, P =0.313) that displayed bony ingrowth with no further progression of subsidence at final follow-up. An intraoperative minor femur neck fracture (P =1.00) occurred in two patients (one in group A and one in group B). These patients were treated by cerclage wires without further incident. Three patients (two in group A: valgus and a CCD angle 135°, and one in group B: varus) had malalignment (P = 0.554) that was not associated with loosening. One patient in group A with a CCD angle of 135° had greater than 1 cm leg length discrepancy (shortening, P = 0.313). Two patients in group B had thigh pain (P = 0.151) that disappeared after a few months. Three patients (one in group A and two in group B) had heterotopic ossifications (P = 0.554) that were categorized as Brooker class I in two patients and class II in one patient without limiting their activities. In conclusion, no significant differences in the clinical and radiographic outcomes as well as component-specific complications were observed between the two groups, showing satisfactory performance at the 5-year follow-up. Group A had a higher incidence of malalignment and subsidence and a lower incidence of thigh pain and proximal bone resorption than group B.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_7 | Pages 26 - 26
1 May 2016
Kang H Lee J Bae K
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Thermal injury to the radial nerve caused by cement leakage is a rare complication after revision elbow arthroplasty. Several reports have described nerve palsy caused by cement leakage after hip arthroplasty. However, little information is available regarding whether radial nerve injury due to cement leakage after humeral stem revision will recover. In a recent study, radial nerve palsy occurred in 2 of 7 patients who had thermal injury from leaked cement during humeral component revisions. These patients did not regain function of the radial nerve after observation. We present a case of functional recovery from a radial nerve palsy caused by cement leakage after immediate nerve decompression in revision elbow arthroplasty[Fig. 1.2].


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_10 | Pages 33 - 33
1 May 2016
Shin Y Lee J Han S
Full Access

We prospectively analyzed 83 patients who underwent ceramic-on-ceramic THA using preassembled (n = 22) or modular acetabular components (n = 61) between June 2010 and June 2012. No radiographic evidence of progressive radiolucency, osteolytic lesions, acetabular fractures, or component migration was detected in either group. Furthermore, no patient required revision surgery for instability or ceramic breakage. Table 1 shows the mean postoperative HHS, WOMAC score, and acetabular component inclination and anteversion in groups A and B. No significant differences in mean postoperative HHS (P < 0.056), WOMAC score (P < 0.258), acetabular component inclination (P < 0.827), or anteversion (P < 0.549) were observed between the two groups according to the independent sample t-test. However, the chi-square (Fisher's exact) test showed a significant difference between the two groups with respect to the gender of the patients (P < 0.001, Table 2). These findings indicate that half of the women had smaller acetabular diameters accommodating a cup size of only 48–50-mm. Thus a preassembled ceramic liner is a very good option for women with a small acetabulum, which could permit the use of a larger femoral head (36-mm) with thin-walled acetabular components. In contrast, the component-specific complications between the two groups were quite similar. One patient (group B) had transient squeaking that disappeared after a few months. One patient (group B) had a mild limp caused by abductor muscle weakness, and one patient (group B) had a superficial wound infection that was treated with local debridement and antibiotics. Early dislocation (P < 0.488) occurred in three patients (one in group A and two in group B). Two patients (one in group A and one in group B) reported postoperative falling events at their bedside. The other in group B was a female with rheumatoid arthritis, which can lead to a much higher risk of dislocation due to soft tissue laxity around the hip joint. All of these patients were treated by closed reduction without further incident. Three patients (one in group A and two in group B) had mild iliopsoas pain (P < 0.488) that was not associated with loosening; however, the pain did not limit their activities (Table 3). In conclusion, we found no significant differences in the mean postoperative radiographic or functional outcomes or complications between the two groups, showing satisfactory performance at the 2 year follow up. Only the gender of the patient was significantly different between the two goups, demonstrating that a larger number of women had smaller acetabular diameters accommodating a cup size of only 48–50-mm. Although a preassembled cup with a 36-mm ceramic liner has proven safety in the short term, future research should focus on its long-term risks.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_7 | Pages 83 - 83
1 May 2016
Chun Y Rhyu K Baek J Oh K Lee J Cho Y
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Purpose

The purpose of this study was to evaluate and compare the clinical, radiological outcomes of the group of patients with distal femoral cortical hypertrophy (DFCH) and without DFCH after hip arthroplasty using a cementless double tapered femoral stem and to analyze a correlation between patients factors and DFCH.

Materials and Methods

Four hundreds four patients (437 hips) who underwent total hip arthroplasty (n = 293) or hemiarthroplasty (n = 144) using a Accolade TMZF femoral stem between Jun 2006 and March 2012 and were follow up period more than 24 months after surgery were enrolled in this study. They were divided into 2 groups, the one group (n = 27) included patients with DFCH, and the other group (n = 410) included patients without DFCH. The mean follow up period was 54.5 months (range, 24 to 85 months) and 56.2 months (range, 24 to 92 months) for patients with DFCH and without DFCH.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_2 | Pages 147 - 147
1 Jan 2016
Lee T Lee J Bouzarif G McGarry M Schwarzkopf R
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INTRODUCTION

Total knee arthroplasty (TKA) is a very successful procedure with good clinical outcomes. However, the effects of obesity on TKA outcomes remain controversial and inconclusive. The objective of this study was to quantify the biomechanical effects of simulated obesity on Cruciate Retaining (CR) and Posterior Stabilized (PS) TKA in human cadaveric knees. We hypothesized that biomechanical characteristics of CR TKA will be less dependent on simulated obesity compared to PS TKA.

METHODS

Eight cadaveric knees (4 male, 4 female) average age 68.4 years (range, 40–86 years) underwent TKA and were tested using a custom knee testing system. Specifically, Cruciate Retaining (CR) and Posterior Stabilized (PS) Lospa Knee System (Corentec Inc.) were implanted and tested sequentially using internal control experimental design. The muscle loading was determined based on the physiological cross-sectional area ratio of the quadriceps and hamstring muscles. The ratios were then applied to CDC data representing the average male height and used to simulate a BMI of 25, 30, and 35 at knee flexion angles (KFA) of 15, 30, 45, 60, 75, and 90 degrees. Patellofemoral and tibiofemoral joint contact areas and pressures were measured using the K-scan sensor system (Tekscan Inc, South Boston, MA). Contact area, force, pressure and peak contact pressure were obtained and analyzed for each specimen. Knee kinematics were quantified using a Microscribe 3DLX digitizer (Revware Inc, Raleigh, North Carolina). Repeated measure analysis of variance with a Tukey post hoc test was used to compare loading conditions. Comparisons between the CR and PS TKA groups were made with a paired t-test. The significance level was set at 0.05.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_3 | Pages 114 - 114
1 Jan 2016
Yoon S Heo I Lee J Park M
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Background

BHA is popular surgery for femoral neck fractures expecially elderly patients. However, clinical results are variable that factors affecting results are questionable. Therefore we investigated radiologic fators, dysplastic hip whether influences results of BHA.

Methods

Between 2004 and 2009, 200 patients undergoing bipolar hemiarthroplasty for femoral neck fracture were divided two groups; a lateral center edge (LCE) angle of < 16 degree or > 16 degree on anteroposterior radiographs. All surgical procedures were performed by a single surgeon. Dermogrpahic data, the harris hip score, WOMAC index, Koval activity level, and complication were recorded. The minimum follow up interval was 4 years (mean, 7.8 years).


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_3 | Pages 115 - 115
1 Jan 2016
Yoon S Park M Lee J Heo I
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Purpose

The purpose of this study was to evaluate the results of modular revision stems, uncemented fluted, tapered to treat periprosthetic femoral (PFF) fracture; we specifically evaluated fracture union, implant stability, patient outcomes, and complications to compare the differences between cemented and cementless primary stem.

Materials and Methods

We retrospectively reviewed 56 cases of unstable periporsthetic femoral fracture (forty B2 and sixteen B3) treated with the uncemented fluted and tapered modular distal fixation stem with or with or without autogenous bone graft. Clinical outcomes were assessed with Harris Hip Score and WOMAC score. Radiologic evaluations were conducted using Beals and Tower's criteria. Any complication during the follow-up period was recorded.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 286 - 286
1 Jul 2014
Lee J Jeong C
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Summary Statement

The implantation of scaffold-free CTE from suspension culture into growth-plate defects resulted in a significant reduction in growth arrest of the rabbit tibia

Introduction

In childhood and adolescence, the growth plate injury can cause partial premature arrest of growth plate, which can make problems such as leg length discrepancy and angular deformity. Bone bridge resection and variable implantation materials such as fat, bone wax, silastic and craniopalst has been investigated. However, those procedures may show limitations including the control of bone growth and long term safety of implant materials in vivo. As an alternative, homogeneous or heterogeneous cartilage cells and stem cell transplants have been tried. In this method, scaffold for cell transplantation is needed. But, so far the most suitable scaffold has not been established. Recently, some authors generated a cartilage tissue equivalent (CTE) using a suspension culture with biophysical properties similar to native hyaline cartilage. Therefore we are able to transplant the CTE without scaffold to the physeal defect. The purpose of this study was to investigated the effects of a transplantation of a vitro-generated scaffold-free tissue-engineered cartilage tissue equivalent (CTE) using a suspension chondrocyte culture in a rabbit growth arrest model.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 64 - 64
1 Dec 2013
Noticewala M Cassidy K Macaulay W Lee J Geller J
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Introduction:

Total hip arthroplasty (THA) is extremely effective in treating debilitating arthritic conditions of the hip. With the many modular prosthetic designs available, surgeons can now precisely construct mechanical parameters such as femoral offset (FO). Although several studies have investigated relationships between offset choice and hip abductor strength, hip range of motion, and prosthetic wear rate, there is scarce data on the effect of FO on pain and functional outcomes following THA. The objective of this study was to assess the effect of restoring FO (within varying degrees compared to the contralateral non-diseased hip [CL]) on physical function, mental well-being, pain, and stiffness outcomes as measured by the Short Form 12 Health Survey (SF-12) and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) at post-operative follow-up.

Methods:

We prospectively collected data on 249 patients that underwent unilateral THA with no or minimal disease of the contralateral hip. Baseline data collection included: age, gender, diagnosis, femoral head size, type of stem, and pre-operative SF-12 and WOMAC scores. Post-operative SF-12 and WOMAC scores were recorded during annual follow-up visits. Post-operative FO was retrospectively measured on standard anteroposterior (AP) pelvis radiographs and compared to FO of CL. FO was measured as the perpendicular distance from the femoral head center of rotation to the anatomic axis of the femur with appropriate adjustments made for image magnification. Patients were categorized into one of three groups: decreased femoral offset (dFO, less than −5 mm compared to CL), normal femoral offset (nFO, between −5 and +5 mm of CL), and increased femoral offset (iFO, greater than +5 mm compared to CL).


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 395 - 395
1 Dec 2013
Lee J Yoon J Lee J
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To investigate the effectiveness of avulsion fracture of tibial insertion of posterior cruciate ligament using the safe postero-medial approach through analyzing the clinical and radiographic outcomes. We treated 14 cases of acute PCL tibial avulsion fracture with “safe postero-medial approach”. The PCL and avulsion bony fragment was fixed with 1 cannuated screw and washer. The patients were assessed clinically and radiographically at 3 months, 6 months, and 12 months. Clinical examination for each visit included assessment of the knee range of motion, using goniometer and the posterior drawer test. The patients were evaluated according to the Lysholm and Tegner rating scales. Patients were followed-up for 12 to 16 months. X-ray showed that satisfactory reducdtion and bony healing was achieved in all cases. There was no neurovascular complication. All patients had negative posterior drawer tests. Excellent outcomes were reported by all patients with the Lysholm score system. And there was no signicant difference between the Tegner scores before injury and last follow-up. Surgical treatment of acute tibial avulsion fracture of the PCL with this approach can restore the stability and fuction of the joint safely in most patients without neurovascular complication. Therefore “safe postero-medial approach” may be suitable for the treatment of isolated tibial avulsion fracture of the PCL.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_15 | Pages 36 - 36
1 Mar 2013
Cho YJ Lee J Kwak S Chun YS Rhyu KH Won YY Yoo M
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Purpose

There are some concerns about doing hip resurfacing arthroplasty in ONFH due to bone defect which can cause mechanical weakness of femoral component and highly active young age of patients which can cause high wear rate and failure rate. The purpose of this study is to verify the HRA is safe procedure in ONFH in the aspect of mechanical and biological issue.

Materials and Methods

Between December 1998 and May 2005, 185 hips of 169 patients underwent MoM HRA using Birmingham Hip Resurfacing System® at single center. 166 hips (26 hips of female, 140 hips of male) of 144 patients have been reviewed for at least 7 years after MoM HRA. Mean follow-up period was 101.8 (84–178) months. Their mean age at the time of operation was 37.7(16–67) years old. Clinically, Harris hip scores (HHS), UCLA activity scores and range of motion were evaluated. Radiologically, the extent of necrotic area in preoperative MRI and radiolucency around implants, narrowing of retained neck, impingement, stress shielding, and heterotopic ossification were evaluated in the serial anteroposterior and groin lateral radiographs of hip. Complications were defined as joint dislocation, infection, implant loosening, femoral neck fracture and pseudotumor. Failure was defined as revision arthroplasty due to the complications.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_15 | Pages 238 - 238
1 Mar 2013
Park HG Lee J
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Purpose

To evaluate the accuracy of the alignment of lower extremity in 661 cases of total knee replacement arthroplasty (TKA) using navigation system.

Materials and method

From June 2006 to September 2008, 661 cases (431 patients) of TKA using navigation system were operated. To analyze the mechanical axis, the weight bearing full length lower extremity radiographs were taken preoperatively and 3 weeks after the operation. The results from a well- experienced surgeon (423 cases) were compared with those from a less-experienced surgeon (238 cases), and they both used the navigation.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_15 | Pages 147 - 147
1 Mar 2013
Cho YJ Lee J Chun YS Rhyu KH Kwak S Won YY Yoo M
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Purpose

In general, the amount and rate of linear wear are associated with femoral head size in the conventional UHMWPE acetabular liner. The smaller the femoral head, the higher the linear wear rate. The aim of this study is to verify the relationship between wear rate and femoral head size and the polyethylene cup thickness.

Materials and Methods

We conducted a retrospective review of all patients who had undergone primary cementless total hip arthroplasty using the conventional UHMWPE (HGP2) acetabular liner between July 1992 and December 2002. 128 hips (34 hips of female, 94 hips of male) of 64 patients who had 28 mm femoral head with different polyethylene acetabular linear thickness and 102 hips (41 hips of female, 61 hips of male) of 81 patients with 22 mm femoral head were included. Patients were assessed clinically and radiographically at postop 6 weeks, 3 months, 6 months and annually thereafter. Clinical assessment was performed using Harris Hip Score. Radiographic analysis included measurement of acetabular component position, polyethylene wear using a validated radiographic technique (Dorr method). Their mean age at the time of operation was 45.3 (24–81) years old and mean follow-up period was 10.8 (96–144 months) years.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_15 | Pages 113 - 113
1 Mar 2013
Cho YJ Lee J Chun YS Rhyu KH Kwak S Ji H Won YY Yoo M
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Purpose

To evaluate the radiological changes after metal on metal resurfacing arthroplasty.

Materials and Methods

Between December 1998 and August 2004, 166 hips in 150 patients who underwent metal resurfacing arthroplasty and followed up more than 4 years. Their mean age at the time of operation was 37.3 years(range, 15–68 years) and mean period of follow-up was 6.1 years(range, 48–95 months). The cause of arthroplasty included 115 avascular necrosis, 43 osteoarthritis, 7 ankylosing spondylitis, 1 haemophilic arthropathy. All patients had anteroposterior, translateral radiographs of the hip made preoperatively and each follow-up visit, and we analyzed radiographic findings such as radiolucencies or impingement signs around implant, neck narrowing and heterotopic ossification.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 518 - 518
1 Sep 2012
Lee C Itoi E Kim S Lee J Jung K Lee S Suh K
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Introduction

Many literatures regarding more specific tests to diagnose the supraspinatus tendon injuries and the best rehabilitation methods to strengthen the supraspinatus have been published. However, conflicting results have been reported. 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography (PET) has been recently used to assess skeletal muscle activities in various fields.

Purpose

To evaluate & compare the metabolic activities of deltoid & rotator cuff muscles after the full-can & empty-can exercises using PET-CT.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XLI | Pages 67 - 67
1 Sep 2012
Raniga S Lee J Perry A Darley D Hurley-Watts C
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The aim of this study was to prospectively assess the results of a preoperative surgical safety checklist by comparing the initial phase of implementation of the Time Out Procedure (TOP) to the results four years later. We compared the accuracy and acceptance of the TOP to determine whether surgical practice had changed.

The TOP was initiated for all elective surgical procedures performed in Christchurch in 2004. An initial audit from September 2004 – April 2005 (Phase 1) was compared to one from October 2008-September 2009 (Phase 2) looking for an improvement in completion of the procedure. Variances were recorded and analysed within the categories of 1 System and process 2 Consent and limb marking 3Incorrect details and 4 Near miss. A questionnaire was also sent to all the surgeons to determine their attitude towards the TOP.

Although the TOP was completed more often in Phase 2 (98%, p<0.001) there were more variances (9%, p<0.001). The commonest variance was due to the surgeon and assistant not being present at the TOP which was significantly worse than in Phase 1 (p<0.0001). The results of the surgeon questionaire showed that only 88% agreed that the TOP was valuable in preventing wrong site surgery.

This surgical indifference to the TOP is difficult to explain especially when National and International agencies have stressed its role in preventing surgical error. The recent introduction of the expanded WHO Checklist should be ‘surgeon led’ to be effective.


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 1 | Pages 93 - 97
1 Jan 2012
Lee JH Lee J Park JW Shin YH

In patients with osteoporosis there is always a strong possibility that pedicle screws will loosen. This makes it difficult to select the appropriate osteoporotic patient for a spinal fusion. The purpose of this study was to determine the correlation between bone mineral density (BMD) and the magnitude of torque required to insert a pedicle screw. To accomplish this, 181 patients with degenerative disease of the lumbar spine were studied prospectively. Each underwent dual-energy x-ray absorptiometry (DEXA) and intra-operative measurement of the torque required to insert each pedicle screw. The levels of torque generated in patients with osteoporosis and osteopenia were significantly lower than those achieved in normal patients. Positive correlations were observed between BMD and T-value at the instrumented lumbar vertebrae, mean BMD and mean T-value of the lumbar vertebrae, and mean BMD and mean T-value of the proximal femur. The predictive torque (Nm) generated during pedicle screw insertion was [-0.127 + 1.62 × (BMD at the corresponding lumbar vertebrae)], as measured by linear regression analysis. The positive correlation between BMD and the maximum torque required to insert a pedicle screw suggests that pre-operative assessment of BMD may be useful in determining the ultimate strength of fixation of a device, as well as the number of levels that need to be fixed with pedicle screws in patients who are suspected of having osteoporosis.