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To date, few studies have investigated the feasibility of the loop-mediated isothermal amplification (LAMP) assay for identifying pathogens in tissue samples. This study aimed to investigate the feasibility of LAMP for the rapid detection of methicillin-susceptible or methicillin-resistant Staphylococcus aureus (MSSA or MRSA) in tissue samples, using a bead-beating DNA extraction method. Twenty tissue samples infected with either MSSA (n = 10) or MRSA (n = 10) were obtained from patients who underwent orthopedic surgery for suspected musculoskeletal infection between December 2019 and September 2020. DNA was extracted from the infected tissue samples using the bead-beating method. A multiplex LAMP assay was conducted to identify MSSA and MRSA infections. To recognize the Staphylococcus genus, S. aureus, and methicillin resistance, 3 sets of 6 primers for the 16S ribosomal ribonucleic acid (rRNA) and the femA and mecA genes were used, respectively. The limit of detection and sensitivity (detection rate) of the LAMP assay for diagnosing MSSA and MRSA infection were analyzed. The results of this study suggest that the LAMP assay performed with tissue DNA samples can be a useful diagnostic method for the rapid detection of musculoskeletal infections caused by MSSA and MRSA.


Aims

To test the hypothesis that reseeded anterior cruciate ligament (ACL)-derived cells have a better ability to survive and integrate into tendon extracellular matrix (ECM) and accelerate the ligamentization process, compared to adipose-derived mesenchymal stem cells (ADMSCs).

Methods

Acellularized tibialis allograft tendons were used. Tendons were randomly reseeded with ACL-derived cells or ADMSCs. ACL-derived cells were harvested and isolated from remnants of ruptured ACLs during reconstruction surgery and cultured at passage three. Cell suspensions (200 µl) containing 2 × 106 ACL-derived cells or ADMSCs were prepared for the purpose of reseeding. At days 1, 3, and 7 post-reseeding, graft composites were assessed for repopulation with histological and immunohistochemical analysis. Matrix protein contents and gene expression levels were analyzed.


Introduction

The degree of cartilage degeneration assessed intraoperatively may not be sufficient as a criterion for patellar resurfacing in total knee arthroplasty (TKA). However, single-photon emission tomography/computed tomography (SPECT/CT) is useful for detecting osteoarthritic involvement deeper in the subchondral bone. The purpose of the study was to determine whether SPECT/CT reflected the cartilage lesion underneath the patella in patients with end-stage osteoarthritis (OA) and whether clinical outcomes after TKA without patellar resurfacing differed according to the severity of patellofemoral (PF) OA determined by visual assessment and SPECT/CT findings.

Methods

This study included 206 knees which underwent TKA. The degree of cartilage degeneration was graded intraoperatively according to the International Cartilage Repair Society grading system. Subjects were classified into four groups according to the degree of bone tracer uptake (BTU) on SPECT/CT in the PF joint. The Feller's patella score and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed preoperatively and postoperative 1 and 2 years.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_1 | Pages 4 - 4
1 Feb 2020
Oni J Yi P Wei J Kim T Sair H Fritz J Hager G
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Introduction

Automated identification of arthroplasty implants could aid in pre-operative planning and is a task which could be facilitated through artificial intelligence (AI) and deep learning. The purpose of this study was to develop and test the performance of a deep learning system (DLS) for automated identification and classification of knee arthroplasty (KA) on radiographs.

Methods

We collected 237 AP knee radiographs with equal proportions of native knees, total KA (TKA), and unicompartmental KA (UKA), as well as 274 radiographs with equal proportions of Smith & Nephew Journey and Zimmer NexGen TKAs. Data augmentation was used to increase the number of images available for DLS development. These images were used to train, validate, and test deep convolutional neural networks (DCNN) to 1) detect the presence of TKA; 2) differentiate between TKA and UKA; and 3) differentiate between the 2 TKA models. Receiver operating characteristic (ROC) curves were generated with area under the curve (AUC) calculated to assess test performance.


The Bone & Joint Journal
Vol. 101-B, Issue 1 | Pages 75 - 82
1 Jan 2019
Kim J Lee SY Jung JH Kim SW Oh J Park MS Chang H Kim T

Aims

The aim of this study was to evaluate the outcome of spinal instrumentation in haemodialyzed patients with native pyogenic spondylodiscitis. Spinal instrumentation in these patients can be dangerous due to rates of complications and mortality, and biofilm formation on the instrumentation.

Patients and Methods

A total of 134 haemodialyzed patients aged more than 50 years who underwent surgical treatment for pyogenic spondylodiscitis were included in the study. Their mean age was 66.4 years (50 to 83); 66 were male (49.3%) and 68 were female (50.7%). They were divided into two groups according to whether spinal instrumentation was used or not. Propensity score matching was used to attenuate the potential selection bias. The outcome of treatment was compared between these two groups.


Bone & Joint Research
Vol. 6, Issue 5 | Pages 337 - 344
1 May 2017
Kim J Hwang JY Oh JK Park MS Kim SW Chang H Kim T

Objectives

The objective of this study was to assess the association between whole body sagittal balance and risk of falls in elderly patients who have sought treatment for back pain. Balanced spinal sagittal alignment is known to be important for the prevention of falls. However, spinal sagittal imbalance can be markedly compensated by the lower extremities, and whole body sagittal balance including the lower extremities should be assessed to evaluate actual imbalances related to falls.

Methods

Patients over 70 years old who visited an outpatient clinic for back pain treatment and underwent a standing whole-body radiograph were enrolled. Falls were prospectively assessed for 12 months using a monthly fall diary, and patients were divided into fallers and non-fallers according to the history of falls. Radiological parameters from whole-body radiographs and clinical data were compared between the two groups.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 150 - 150
1 Mar 2017
Shon W Dwivedi C Kim T Kim H
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Although total hip arthroplasty is highly successful for treatment of osteoarthrosis of hip joint, it is skill demanding surgery to perform and even more challenging in case of revision with bone defects. There are many options available for reconstruction of acetabular bony defects. Here, we evaluate the outcome of acetabular bony defect reconstructed with trabecular metal augments in short term.

We performed, 22 revision total hip arthroplasties and 6 primary total hip arthroplasties (total 28 in 28 patients) using trabecular metal augments to reconstruct acetabular defect between 2011 to 2015. Out of these 28 patients, 18 were males and 10 were females. Mean age of these patients was 61.2 years (range: 46 years to 79 years). Pre-operative templating was done for all cases and need for trabecular metal augments was anticipated in all cases. All cases were classified according to Paprosky classification for acetabular bone defects. Out of 28 patients, 3 had type 2B, 1 had type 2C, 18 had type 3A and 6 had type 3B acetabular defects. Post operatively, all patients were followed at regular interval for their clinical and radiological outcome. An average follow up was 20.1 months (range: 6 months to 42.5 months). We assessed clinical outcome in the form of Herris hip score (HHS) and radiological outcomes in form of osteolysis in acetabular zones and osseointegration, according to the criteria of Moore.

The average Harris hip score (HHS) was improved from 58.0 preoperatively to 87.2 postoperatively. The average degree of cup abduction at the final follow up was 44.29. The centre of rotation of the hip joint was corrected from average 38.90mm (range: 22.15mm to 66.35mm) above the inter-teardrop line preoperatively to average 23.85mm (range: 11.82mm to 37.69mm) above the inter-teardrop line postoperatively. Out of 28 patients, 18 patients had three or more signs of osseointegration, according to the criteria of Moore, at the time of final follow up. Rest of patients, had one or two signs of osseointegration (5 patients had one sign and 5 patients had two signs). We had no patient with migration or loosening of acetabular components. No patient has osteolysis of acetabulum in any zone.

Trabecular metal augments provide good initial stability to acetabular cup as well as helpful to bring down the centre of rotation of the hip joint within limit of 35mm above the inter-teardrop line. They also facilitate osseointegration. Our study showed that the results of the trabecular metal augments in reconstruction of acetabular bony defects were successful even in short term. However, long term study is required for better evaluation.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_6 | Pages 1 - 1
1 Mar 2017
Clarke I Kim T Swaminathan S Shon W Donaldson T
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Hip simulator studies with ceramic-on-metal (COM) predicted less wear than metal-on-metal (MOM: Isaac. 2009). While clinical evidence is scant, two COM case reports described pseudotumors with adverse cup positioning (Deshmukh 2012, Koper 2014). It would appear that our Korean case report is the first to describe pseudotumor formation in well-positioned COM arthroplasty and including detailed failure analysis. A 50-year old female (active salesperson) had bilateral avascular necrosis of her femoral heads. A left metal-on-polyethylene (MPE) hip was performed at outside institution in 2003. At our 3-yrs evaluation, radiographs showed well-functioning MPE hip. Five years later she complained of gradual left-hip pain (2011). Radiographs and CT scan demonstrated wear, osteolysis and loosening of both components. The revision in 2011 was by COM (Fig. 1), using S-ROM stem/sleeve, 36mm ceramic head (Biolox-delta), a CoCr liner and 54mm shell (Pinnacle: Depuy Inc). Cup inclination and anteversion were considered appropriate at 45° and 20° respectively; femoral anteversion of 15° was also appropriate.

At 1-yr follow-up patient complained of mild discomfort in left COM hip (2012). Range of motion was painless and normal. Examination revealed a soft, non-tender swelling (2×3cm) in left inguinal region with no inflammation and radiographs were normal (Fig. 1a). One month later the patient complained of left hip pain, the previously noted swelling had increased in size, and she started to limp. Radiographs showed cup migration with increased inclination. CT scans showed a circumscribed lesion extending into iliopsoas region (Fig 2). Serum cobalt and chromium levels were high at 2.4 and 22.5µg/ L, respectively.

At revision the pseudotumor and surrounding inflamed synovium was excised. The cystic soft-tissue swelling (stained black) extended into the joint (Fig. 2a). The ceramic head showed a large “black stripe” across the dome (Fig 2b). The cup was loose while the femoral stem was well fixed. Operative cultures of soft tissues and joint fluid were negative for infection while histopathology was consistent for metallosis (Fig. 3). Aggressive debridement was carried out, acetabular defects were filled with bone graft. Revision incorporated 32mm ceramic head (Biolox-delta), highly cross-linked liner and 52mm trabecular-metal shell (Depuy). Functionally the patient has continued to improve. By 6 months, serum ion concentrations decreased to Co:1.3 and Cr:2.54µg/ L with most recent ion levels lower still (Co:0.66 and Cr:0.42µg/ L).

Ceramic head surfaces showed normal wear appearance. The large gray stripe identified on the highly polished dome contained Co and Cr metal-transfer from the CoCr liner (Fig. 2b). Thin gray stripes on equatorial head regions (x4 rougher than dome) represented contamination by Ti, Al and V, typical of adverse impingement against Ti6Al4V neck (Clarke 2013). There was a 100–150um defect on rim of CoCr liner as a result of impingement. Cup out-of-roundness was 476um compared to only 7um for ceramic head, thus cup wear dominated at 25–30mm3 volume. This case report was illustrative of the unpredictable and seldom diagnosed risk of habitual cup-to-neck impingement and the risk of relying on pristine simulator studies to predict outcomes in novel THA bearings.

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Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 33 - 33
1 Feb 2017
Jang K Lee D Kim T In Y Oh K Lee D Han S
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Purpose

This meta-analysis was designed to evaluate the effects of computer navigation on blood conservation after total knee arthroplasty (TKA) by comparing postoperative blood loss and need for allogenic blood transfusion in patients undergoing computer navigation and conventional primary TKAs.

Methods

Studies were included in this meta-analysis if they compared change in haemoglobin concentration before and after surgery, postoperative blood loss via drainage or calculated total blood loss, and/or allogenic blood transfusion rate following TKA using computer navigation and conventional methods. For all comparisons, odds ratios and 95 % confidence intervals (CI) were calculated for binary outcomes, while mean difference and 95 % CI were calculated for continuous outcomes.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_23 | Pages 63 - 63
1 Dec 2016
Chen A Kazarian G Kim T Hollern D Deirmengian C
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Aim

Hospital systems have recently instituted early systemic sepsis recognition systems, where vital signs and laboratory findings are monitored and automatically alert providers to potential sepsis. Although there are very few reports evaluating the use of sepsis alert systems outside of the emergency room or intensive care unit, many hospital systems have made the decision to apply the sepsis alarm protocols to all inpatients. The purpose of this study was to evaluate if an alarm system using systemic inflammatory response syndrome (SIRS) criteria is a valuable tool to predict systemic sepsis in the immediate postoperative period (POD#0–4) after total joint arthroplasty (TJA).

Method

10,791 primary and revision TJA patients at one institution, from 2010–2014, were retrospectively reviewed for positive SIRS criteria on each hospital day from the date of surgery to postoperative day four (POD#4). SIRS criteria included temperature > 38°C or < 36°C, heart rate > 90 beats per minute, respiratory rate > 20 breaths per minute, and white blood cell (WBC) > 12,000/mm3 or < 4,000/mm3. Additionally, hospital coding data was cross-referenced to identify patients who were diagnosed with systemic sepsis within 10 days after having a TJA.


Bone & Joint Research
Vol. 5, Issue 11 | Pages 544 - 551
1 Nov 2016
Kim Y Bok DH Chang H Kim SW Park MS Oh JK Kim J Kim T

Objectives

Although vertebroplasty is very effective for relieving acute pain from an osteoporotic vertebral compression fracture, not all patients who undergo vertebroplasty receive the same degree of benefit from the procedure. In order to identify the ideal candidate for vertebroplasty, pre-operative prognostic demographic or clinico-radiological factors need to be identified. The objective of this study was to identify the pre-operative prognostic factors related to the effect of vertebroplasty on acute pain control using a cohort of surgically and non-surgically managed patients.

Patients and Methods

Patients with single-level acute osteoporotic vertebral compression fracture at thoracolumbar junction (T10 to L2) were followed. If the patients were not satisfied with acute pain reduction after a three-week conservative treatment, vertebroplasty was recommended. Pain assessment was carried out at the time of diagnosis, as well as three, four, six, and 12 weeks after the diagnosis. The effect of vertebroplasty, compared with conservative treatment, on back pain (visual analogue score, VAS) was analysed with the use of analysis-of-covariance models that adjusted for pre-operative VAS scores.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 44 - 44
1 May 2016
Cho W Oh B Kim T Kim S
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Purpose

Most of revision TKA needs bone reconstruction. The success of revision TKA depends on how well the bone reconstruction can be done. The method of reconstruction includes bone cementing, metal augmentation, allogenic bone graft, APC and tumor prosthesis, etc.

In moderate to severe bone defect, allograft is needed. However, allogenic bone graft is surgically demanding and needs long operation time, which is very risky to the elderly patients. The authors revised an alternative method of bone defect reconstruction using cementing method with multiple screws augmentation.

Methods

There were 12 cases of patients with large defect which could not be reconstructed with metal augment from April 2012 to April 2014. The authors performed 3 to 5 screws fixation on the defect site. Sclerotic bone is prepared with burring for better cementing. 3 ∼ 5 screws according to the size of defect. The length of screw fixation was determined as deep to the bone until stable fixation just beneath the implant. When drilling for the screw insertion, intramedullary guide is put into the medullary canal so as not to interfere with implant insertion. The defect is filled with cement during prosthesis fixation. Weight bearing was permitted on postoperative 3rd day, as usual manner of primary TKA.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 145 - 145
1 May 2016
Lee B Kim T
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Objectives

C-reactive protein(CRP) Used as screening test for acute periprosthetic joint infection has high sensitivity and low specificity. So there are many reasons except acute infection after total knee arthroplasty to elevate CRP level but it is unclear what reasons exactly were concerned. We therefore performed this study to determine the Causes of elevated CRP level in the early-postoperative period after primary total knee arthroplasty.

Methods

Between 2005 and 2013, 502 patients undergone primary total knee arthroplasty were included. We excluded patients performed total knee arthroplasty with inflammatory arthritis and revision total knee arthroplasty, We measured the serial CRP levels in the all cases and then found cases with CRP level show elevation-depression-elevation pattern(bimodal graph) or >23.5mg/dl. We analyzed causes of elevated CRP level of that


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 130 - 130
1 May 2016
Kweon S Kim T Kim J Jeong K
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Purpose

The purpose of this study is to evaluate the clinical outcomes and and radiological findings of primary total hip arthroplasty(THA) performed by using cemented polished femoral stem.

Materials and Methods

We retrospectively reviewed 91 hips (84 patients) that had undergone primary THA with cemented polished femoral stem after follow-up more than 10 years. The mean age at surgery was 57 years old (47 to 75). Mean follow up period was 12. 8 years(10.1 to 14). Clinical evaluation was performed using Harris hip score. The radiographic evaluation was performed in terms of the cementing technique, including of subsidence within the cement mantle, radiolucent lines at the cement-bone or cement-stem interface, cortical hypertrophy, and calcar resorption.


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 7 | Pages 956 - 960
1 Jul 2012
Kim T Ha Y Kang B Lee Y Koo K

This prospective multicentre study was undertaken to determine whether the timing of the post-operative administration of bisphosphonate affects fracture healing and the rate of complication following an intertrochanteric fracture. Between August 2008 and December 2009, 90 patients with an intertrochanteric fracture who underwent internal fixation were randomised to three groups according to the timing of the commencement of risedronate treatment after surgery: Group A (from one week after surgery), Group B (from one month after surgery), and Group C (from three months after surgery). The radiological time to fracture healing was assessed as the primary endpoint, and the incidence of complications, including excessive displacement or any complication requiring revision surgery, as the secondary endpoint. The mean time to fracture healing post-operatively in groups A, B and C was 10.7 weeks (sd 4.4), 12.9 weeks (sd 6.2) and 12.3 weeks (sd 7.1), respectively (p = 0.420). At 24 weeks after surgery, all fractures had united, except six that had a loss of fixation. Functional outcomes at one year after surgery according to the Koval classification (p = 0.948) and the incidence of complications (p = 0.386) were similar in the three groups.

This study demonstrates that the timing of the post-operative administration of bisphosphonates does not appear to affect the rate of healing of an intertrochanteric fracture or the incidence of complications.


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 7 | Pages 961 - 966
1 Jul 2011
Park Y Kim J Ryu J Kim T

A number of causes have been advanced to explain the destructive discovertebral (Andersson) lesions that occur in ankylosing spondylitis, and various treatments have been proposed, depending on the presumed cause. The purpose of this study was to identify the causes of these lesions by defining their clinical and radiological characteristics.

We retrospectively reviewed 622 patients with ankylosing spondylitis. In all, 33 patients (5.3%) had these lesions, affecting 100 spinal segments. Inflammatory lesions were found in 91 segments of 24 patients (3.9%) and traumatic lesions in nine segments of nine patients (1.4%). The inflammatory lesions were associated with recent-onset disease; a low modified Stoke ankylosing spondylitis spine score (mSASSS) due to incomplete bony ankylosis between vertebral bodies; multiple lesions; inflammatory changes on MRI; reversal of the inflammatory changes and central bony ankylosis at follow-up; and a good response to anti-inflammatory drugs. Traumatic lesions were associated with prolonged disease duration; a high mSASSS due to complete bony ankylosis between vertebral bodies; a previous history of trauma; single lesions; nonunion of fractures of the posterior column; acute kyphoscoliotic deformity with the lesion at the apex; instability, and the need for operative treatment due to that instability.

It is essential to distinguish between inflammatory and traumatic Andersson lesions, as the former respond to medical treatment whereas the latter require surgery.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 128 - 128
1 Mar 2010
Kwon S Kang Y Chang C Seong S Kim T
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In a previous study, we found that pre-TKA patients were severely disabled in high-flexion activities but perceived these disabilities as being no more important than pain relief and the restoration of daily routine activities. This study was conducted to investigate functional disabilities and patient satisfaction in Korean patients after TKA.

Of 387 patients who had undergone TKA with a follow-up longer than 12 months, 270 (69.7%) completed a questionnaire designed to evaluate functional disabilities, perceived importance and patient satisfaction.

The top 5 severe functional disabilities were difficulties in kneeling, squatting, sitting with legs crossed, sexual activity, and recreational activities. The top 5 in order of perceived importance were difficulties in walking, using a bathtub, working, climbing stairs, and recreation activities. Severities of functional disabilities were not found to be correlated with perceived importance. The patients (8.5%) dissatisfied with their replaced knees had more severe functional disabilities than the satisfied for most activities. The dissatisfied patients tended to perceive functional disabilities in high-flexion activities to be more important than the satisfied.

This study indicates that despite severe disabilities in high-flexion activities, most Korean patients after TKA would not consider high-flexion disability to be more important than other daily routine activities. Moreover, postoperative high-flexion disabilities would not adversely influence satisfaction for most patients. Nevertheless, such disabilities are likely to cause dissatisfaction among those that are not prepared to modify their traditional life-styles.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 119 - 120
1 Mar 2010
Kim T Seong S Lee S Kim D Lee M
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The aim of this study was to evaluate passive kinematics of a mobile-bearing, ultracongruent (UC) total knee design compared with a mobile-bearing, posterior stabilised (PS) design intraoperatively using navigation system.

Thirty-four knees of 24 patients which had undergone total knee arthroplasty with UC prosthesis (E-motion®, Aesculap, Tuttlingen, Germany) for primary osteoarthritis and fifteen knees of 14 patients with PS prosthesis (E-motion®) were included in this study. Thirty-one female and seven male patients were included and the mean age was 70.4 years. Patients were followed up for 7.26 months (6 to 12 months). Intraoperative kinematics including valgus/varus rotation, internal/external rotation, and anterior/posterior translation was assessed from 10° to 120° of passive flexion before and after total knee replacement using a surgical navigation system (Orthopilot®, Aesculap). The range of motion (ROM) was measured preoperatively and at the final follow up.

The tibiofemoral alignment in 10° flexion changed from varus 5.85° to valgus 0.38° in UC group and changed from varus 7.45° to valgus 1.08° in PS group (p> 0.05), the magnitude of varus rotation during flexion was 0.01° in UC group and 4.08° in PS group (p< 0.05). PS knee showed the tendency to slight varus alignment during flexion but UC knee showed the tendency toward valgus alignment fter midflexion. The mean internal rotation during flexion was 10.3° in UC group and 13.2° in PS group (p> 0.05). The translation of the femur was 4.99mm posteriorly in UC group and 3.24mm posteriorly in PS group at 120° flexion (p> 0.05). The maximum flexion angle at the final follow up was 123° in UC group and 118° in PS group (p> 0.05). Total knee arthroplasty with high flexion PS prosthesis showed good ROM and satisfactory early clinical results.

UC total knee design showed less varus rotation during flexion, more valgus pattern in higher flexion angle than PS design, similar internal rotation angle and pattern, and similar posterior translation at 120° flexion with PS design.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 147 - 147
1 Mar 2010
Shin DS Lee H Kim T Oh K
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The anterior pelvic plane has been introduced as a concept of the reference plane to image free navigation-assisted cup placement of total hip arthroplasty. With the neutral pelvis, the anteversion relative to the conventional coordinate system is equal to the that of relation to the anatomical coordinate system. This is the rationale of image free navigation system. But, currently, two major concerns about image-free navigation assisted total hip arthroplasty are tilting of anatomic coordinate system and the cutaneous palpation procedure. Therefore, it was the goal of this study to provide both the bone anterior pelvic plane (Bone_APP) and the overlying soft tissue plane (Soft_APP) simultaneously, and to find possible correlations of biometrical parameters and effect of ante-version were an additional motivation of this study. 23 Korean adult patients underwent image-free navigation-assisted total hip arthroplasty. The tilting of Bone_APP, soft tissue thickness on ASIS, pubis, and then tilting of Soft_APP, and anteversion of cup were measured with reconstructed CT and 3D workstation system.

The average age was 66.1 years, the average height was 162.5cm at a weight of 59.2 kg. The average body mass index was 22.3. And the average lumbar lordosis was measured as 30.4 degrees. The soft tissue on the level of the pubis was 17.6 mm thicker than that on the level of ASIS in average. In all cases, Soft_APP was positive, that is from 3.5 to 16.5 degrees of backward rotation. We also found a high-intersubject variability in the Bone_APP from 13.4 of forward rotatation to 23 degrees of backward rotation. Overall, there are no correlation between biometrical parameters and difference of navigated data to others measured on CT. Averaged navigated data was 22.4 degrees. The average anatomic, operative, and planar anteversion were 29.2, 27.2 and 21.3 degrees respectively. The value of anteversion measured on the transverse plane and sagittal plane shows higher than navigated anteversion in paired comparison. This could be comprehended that the navigation system had under-estimated the anteversion than that of transverse and sagittal plane, This means navigation assessed pelvic plane as back ward tilting rather than forward tilting intraoperatively.

None of cases showed the Bone_APP was parallel to conventional coordinate system. Comparing the variable bone APP tilt, all of cases showed an backward tilted soft tissue plane. There were no correlation between bone APP and biometrical parameters. Overall, navigated data were less than anatomic and operative anteversion. Rather than anatomic coordinate system (Bone-APP), backward tilting due to overlying soft tissue (Soft-APP) might to make the navigated data have the tendency to under-estimated the anteversion of cup measured with CT. In conclusion, anterior pelvic plane does not satisfactory reliability with should be easily identified during operation. Image-free navigation system would take into account variations of individuals including both bone tilt and soft tissue plane.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 126 - 126
1 Mar 2010
Chung B Kang Y Chang C Kim S Seong S Kim T
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Despite the well-documented improvement in coronal alignment achieved by computer assisted navigation, varying results have been reported for sagittal alignment. Current navigation systems rely on a sagittal femoral mechanical axis identified by the navigation system, but little information is available on the relationship between the sagittal mechanical axis and anatomical axes for intra-operative or postoperative radiographic assessments. We asked whether deviations exist between sagittal femoral mechanical axis and anatomical axes and attempted to identify predictors of the deviations found.

In 100 consecutive patients (200 knees) undergoing TKA, angles between two anatomical axes (the anterior cortical line and mid-medullary line) and two sagittal mechanical axes identified by current navigation systems were measured as proxies of the deviations between them on true lateral radiographs of the whole femur. Correlation analyses and multivariate regression were carried out to identify predictors of deviations.

Significant deviations existed with wide ranges between the anatomical axes and the sagittal mechanical axes. Degree of femoral bowing and femoral length were found to be predictors of deviations between sagittal femoral mechanical axes and anatomical axes.

This study suggests that surgeons applying navigation technology to TKA need to consider deviations between the sagittal femoral mechanical axes and anatomical axes when they intend to place a femoral component at a target sagittal orientation with respect to an anatomical reference.