Reliability of Imageless Computer-Assisted Navigation for Femoral Rotational Alignment in Total Knee Arthroplasty

@#Introduction: The aim of this study was to evaluate the reliability of the femoral component rotation on intraoperative data recorded in a computer-assisted navigation system (CAN-FRA) compared with the post-operative femoral component rotation observed on computed tomography (CT-FRA). Material and method: Computer-assisted total knee arthroplasty (TKA) or primary osteoarthritis of the knee was performed in 51 knees in 36 patients with a mean age of 69.51 years. All procedures were performed by a single surgeon using the same implant design. The intraclass correlation coefficient (ICC) was used to compare the intraoperative CAN-FRA with the post-operative CT-FRA. The angle between the anatomical epicondylar axis and the posterior condylar axis of the implant (CT-FRA) was measured at two separate timepoints by three observers who were blinded to the intra-operative CAN-FRA. Internal rotation was defined as rotation in the negative direction, while external rotation was defined as positive. Results: The mean intra-operative CAN-FRA was 0.1° ± 2.8° (range -5.0° to 5.5°). The mean post-operative CT-FRA was -1.3° ± 2.1° (range -4.6° to 4.4°). The mean difference between the CAN-FRA and the CT-FRA was -1.3° ± 2.2° (range -7.9° to 2.4°). The respective ICC values for the three observers were 0.92, 0.94, and 0.93, while the respective intra-observer coefficients were 0.91, 0.85, and 0.90. The ICC for the intra-operative CAN-FRA versus the postoperative CT-FRA was 0.71. Conclusion: This study shows that using a computerassisted navigation system in TKA achieves reliable results and helps to achieve optimal positioning of the femoral component and rotation alignment correction.

Combination of measured resection and gap balancing technique used in femoral component rotation in total knee arthroplasty / 中国组织工程研究

BACKGROUND: Total knee arthroplasty is effective in managing end-stage knee disease. Measured resection and gap balancing are two different techniques. Both of two have advantages and disadvantages. A technique has been developed that combines the benefits of measured resection and gap balancing to optimize the clinical effect of total knee arthroplasty. OBJECTIVE: To evaluate the operation and early clinical effect in total knee arthroplasty about the combination of measured resection and gap balancing technique used in femoral component rotation. METHODS: Totally 30 patients were treated with the combination of measured resection and gap balancing technique in total knee arthroplasty from September 2016 to December 2018, including 4 males and 26 females, at the age of 46-81 years. There were 24 cases of osteoarthritis with varus and 2 cases of osteoarthritis with valgus. There were 4 cases of rheumatoid arthritis with valgus. All patients signed the informed consent. This study was approved by the Hospital Ethics Committee. Effects were evaluated by Visual Analogue Scale, Hospital for Special Surgery score, femorotibial angle and range of motion before surgery and during final follow-up. RESULTS AND CONCLUSION: (1) The incision healed in the first stage after operation. No early complications occurred, such as infection, vascular nerve injury, deep venous thrombosis of the lower extremities and periprosthetic fracture. (2) Totally 30 patients were followed up for 6-30 months. (3) Visual Analogue Scale, Hospital for Special Surgery score, range of motion and femorotibial angle were improved during final follow-up compared with those before surgery (P < 0.05). (4) Surgeons should be familiar with measured resection and gap balancing technique in total knee arthroplasty, and then use the combination of two techniques based on the specific situation of patients to obtain better soft tissue balance and prosthesis position. The combination technique is easy to master and can be operated with traditional osteotomy tools. Thus, good short-term effect can be achieved.

Imaging study on effect of femoral intramedullary guide on the alignment of femoral prosthesis in unicompartmental knee arthroplasty / 中国修复重建外科杂志

Objective: To explore the imaging features of intramedullary guide rod and its influence on the alignment of the femoral prosthesis in unicompartmental knee arthroplasty (UKA). Methods: Between August 2016 and November 2016, 50 patients (50 knees) with primary anteromedial osteoarthritis were treated with UKA by Oxford MicroPlasty minimally invasive replacement system. There were 10 males and 40 females. The age ranged from 62 to 77 years with an average of 68.8 years. Preoperative varus and flexion deformity angles were (5.22±3.46)° and (7.42±2.65)°, respectively. The knee range of motion (ROM) was (106.85±7.62)°. The Hospital for Special Surgery (HSS) score was 68.26±4.65. The angles between the femoral intramedullary guide rod and the anatomical axis of femur on the coronal and sagittal planes, the femoral component valgus/varus angle (FCVA), the femoral component posterior slope angle (FCPSA), knee varus deformity angle, and knee flexion deformity angle were measured by intra- and post-operative X-ray films. The postoperative ROM and HSS score were measured. Results: Intraoperative X-ray films measurement showed that the lateral side angles between femoral intramedullary guide rod and femoral anatomical axis were observed on coronal plane, and the angles ranged from 0.28 to 2.06° with an average of 0.96°. While the posterior side angles were observed on sagittal plane, and the angles ranged from 0.09 to 0.48° with an average of 0.23°. The angulations (>1°) between femoral intramedullary part guide rod and outside part of the rod were confirmed in 12 cases (24%) on coronal plane. Postoperative femoral prosthesis were mild varus in 38 patients (76%). The FCVA ranged from -1.76 to 4.08° with an average of 2.21°. The FCPSA ranged from 7.12 to 13.86° with an average of 9.16°. All patients were followed up 22-26 months, with an average of 24.5 months. The incisions healed by first intention. At last follow-up, the varus and flexion deformity angles were (1.82±1.05) and (2.54 ± 1.86)°, respectively. ROM was (124.62±5.85)° and HSS score was 91.58±3.65. There were significant differences between pre- and post-operative parameters ( P<0.05). No complication such as dislocation or aseptic loosening of the prosthesis occurred during the follow-up. Conclusion: UKA by Oxford MicroPlasty minimally invasive replacement system can obtain accurate femoral prosthesis position with the help of intramedullary guide system, and the effectiveness is excellent.

Comparison of Revision Rates Due to Aseptic Loosening between High-Flex and Conventional Knee Prostheses

PURPOSE: The purpose was to evaluate and compare the revision rate due to aseptic loosening between a high-flex prosthesis and a conventional prosthesis. MATERIALS AND METHODS: Two thousand seventy-eight knees (1,377 patients) with at least 2 years of follow-up after total knee arthroplasty were reviewed. Two types of implants were selected (LPS-Flex and LPS, Zimmer) to compare revision and survival rates and sites of loosened prosthesis component. RESULTS: The revision rate of the LPS-Flex (4.9%) was significantly higher than that of the conventional prosthesis (0.6%) (p<0.001). The 5-, 10-, and 15-year survival rates were 98.9%, 96.2% and 92.0%, respectively, for the LPS-Flex and 99.8%, 98.5% and 93.5%, respectively, for the LPS. The survival rate of the high-flex prosthesis was significantly lower than that of the conventional prosthesis, especially in the mid-term period (range, 5 to 10 years; p=0.002). The loosening rate of the femoral component was significantly higher in the LPS-Flex prosthesis (p=0.001). CONCLUSIONS: The LPS-Flex had a higher revision rate due to aseptic loosening than the LPS prosthesis in the large population series with a long follow-up. The LPS-Flex should be used carefully considering the risk of femoral component aseptic loosening in the mid-term (range, 5 to 10 years) follow-up period after initial operation.

Intentionally Increased Flexion Angle of the Femoral Component in Mobile Bearing Unicompartmental Knee Arthroplasty

PURPOSE: The purpose of this study was to determine the results of mobile bearing unicompartmental knee arthroplasty (UKA) with an intentionally increased flexion angle of the femoral component in patients requiring high flexion. MATERIALS AND METHODS: We investigated 45 knees treated by UKA. Clinically, we measured the range of motion (ROM) and the American Knee Society (AKS) score preoperatively and at final follow-up and investigated complications. Radiologically, we measured the flexion angle of the femoral component, the posterior slope angle of the tibial component, the femorotibial angle and mechanical axis of the limb postoperatively. RESULTS: The ROM was increased from 123° preoperatively to 139° at the final follow-up. The AKS knee and function scores increased from 59 and 68, respectively, preoperatively to 94 and 96, respectively, at the final follow-up. The flexion angle of the femoral component was 9.1°, and the posterior slope angle of the tibial component was 8.6°. There was one case of bearing dislocation in the largest femoral flexion angle case. CONCLUSIONS: The results might reflect the positive effect of an increased flexion angle of the femoral component up to 10° on ROM in mobile bearing UKA, which would contribute to better quality of life after UKA especially in populations requiring deep knee flexion.

Comparison of an Accelerometer-Based Portable Navigation System, Patient-Specific Instrumentation, and Conventional Instrumentation for Femoral Alignment in Total Knee Arthroplasty

PURPOSE: The KneeAlign2 (KA2, OrthoAlign Inc.) accelerometer-based portable navigation system and patient-specific instrumentation (PSI; Signature, ZimmerBiomet) are widely used for ideal femoral component alignment in total knee arthroplasty (TKA). However, there has been no comparative study of the KA2 system, PSI, and conventional intramedullary instrumentation (CON). The purpose of this study was to compare the accuracy in achieving proper femoral component alignment and clinical features by using the KA2 navigation system, PSI, and CON. MATERIALS AND METHODS: We retrospectively compared the accuracy of femoral component alignment of 34 TKAs performed with the KA2 system for implantation of the femoral component, 32 TKAs with PSI, and 33 TKAs with CON. RESULTS: In the coronal plane, use of the KA2 system was more likely to result in optimal femoral component alignment than the CON and PSI (p < 0.01). In the sagittal plane, use of the KA2 system was more likely to result in optimal component alignment than PSI, but the difference between the KA2 and CON was insignificant. CONCLUSIONS: The portable accelerometer-based KA2 navigation system enabled ideal femoral implantation in the coronal and sagittal planes, as compared to the PSI or CON.

Efficacy of Extramedullary Femoral Component Alignment Guide System for Blood Saving after Total Knee Arthroplasty

PURPOSE: To compare the extramedullary femoral alignment guide system with the conventional intramedullary alignment guide system for bleeding and transfusion rate after total knee arthroplasty (TKA). MATERIALS AND METHODS: Forty-nine female TKA patients were randomized into two groups: intramedullary (IM) group vs. extramedullary (EM) group. Drained volume of blood, hemoglobin concentration, hemoglobin drop, and transfusion rate were compared between the two groups. Wound problems, bleeding-related problems and thromboembolic complications were collected. RESULTS: The mean drained volume via vacuum drainage was less in the EM group than that in the IM group (482.9 mL vs. 266.8 mL, p=0.001). Hemoglobin at 5 days after surgery was higher in the EM group (9.3 g/dL vs. 9.9 g/dL, p=0.002) than that in the IM group. The drop in hemoglobin after 5 days was smaller in the EM group (3.5 g/dL vs. 2.9 g/dL, p=0.003) than that in the IM group. The EM group had a lower prevalence of allogeneic transfusion (45.0% vs. 20.5%, p=0.026) than that in the IM group. No significant complications developed in either group. CONCLUSIONS: The results suggest that the extramedullary femoral alignment guide technique is an advantageous method that can reduce the drained volume of blood and the allogeneic transfusion rate.

The Correlation of Postoperative Femoral Component Rotation Angle and Patella Tilt Angle with Clinical Results in Total Knee Arthroplasty

PURPOSE: The aim of this study was to analyze the correlation of postoperative femoral component rotation angle and patella tilt angle with clinical results for total knee arthroplasty. MATERIALS AND METHODS: Ninety-six cases in 48 patients who underwent total knee arthroplasty between March 2002 and February 2010 were enrolled. Femoral component rotation angle (FRA) and patella tilt angle (PTA) were measured with postoperative computed tomography. Clinical results were evaluated using American Knee Society knee score & function score and Feller's patella score. We analyzed the correlation of FRA and PTA with clinical outcomes. We also compared clinical results between the PFC(R) Sigma group and the Scorpio NRG(R) group, and the patello-femoral symptom group and a symptom-free group. RESULTS: The mean FRA was 1.40degrees of internal rotation. The patellar tilt angle was 3.79degrees of lateral tilt. The mean knee score was 90.5, the function score was 77.4, and the patella score was 23.9. There was a significant difference between FRA and knee scores (p=0.031, r=-0.284). There were no significant differences between FRA and function score or patella score. The correlation of PTA and clinical results was not significant. The mean FRA was 2.00degrees of internal rotation in the PFC(R) Sigma group, and it was significantly different than for the Scorpio NRG(R) group which had 0.81degrees of internal rotation; but there were no significant differences between the two groups in clinical results. The patello-femoral symptom group deviated more from the mean FRA than did the symptom-free group. CONCLUSION: Internal rotation of the femoral component is correlated with poor clinical results after total knee arthroplasty. The correlation of patella tilt angle and clinical results was not significant.

Anatomical Assessment of the Distal Femur and Tibia for Optimal Femoral Rotational Alignment in Total Knee Arthroplasty

PURPOSE: This study aimed 1) to identify the rotational axis of the femur that provides a balanced 90degrees flexion space in TKA, 2) to assess the changes in the flexion space in deep flexion, and 3) to assess the changes in rotational alignment, with using the posterior condylar axis (PCA) as a guide, and as the changes are related to asymmetric cartilage erosion of the posterior condyle. MATERIALS AND METHODS: The axial MR images of the distal femur in knee extension and the coronal images of the distal femur and the entire tibia at 90 and 130degrees were examined in 40 healthy adults. RESULTS: The clinical transepicondylar axis (TEA) provides a balanced 90degrees flexion space on average. The balanced flexion space in 90degrees became an asymmetrical space with relative narrowing of the medial side in 130degrees. Every 1 mm of asymmetrical cartilage erosion between the posterior condyles changed the femoral rotation by approximately 1degrees when using the PCA as a guide. CONCLUSION: This study suggests that the clinical TEA is the rotational reference that provides a balanced flexion space. When using the PCA as a rotational reference, a surgeon should consider the potential change in the rotational angle that is caused by asymmetrical cartilage erosion.

MRI Measurement of the Distal Femur for Determining the Rotational Alignment in TKA

PURPOSE: The purpose of the current study was to investigate the relationship between the angles made by the reference axes on the axial magnetic resonance (MR) images and to provide information for determining the rotational alignment of the femoral component in total knee arthroplasty. MATERIALS AND METHODS: We analyzed 194 magnetic resonance (MR) images to measure the posterior condylar angle, the condylar twist angle and the difference between the posterior condylar angle and the condylar twist angle. We then evaluated the relationship between these angular measurements. RESULTS: The condylar twist angle averaged 6.09degrees, the posterior condylar angle averaged 2.95degrees and the difference between the posterior condylar angle and the condylar twist angle was 3.14degrees. There were no differences in these angles based on gender and age. CONCLUSION: In the cases that the center of the medial epicondyle is difficult to clearly identify during TKA, the femoral rotational resection angle can be determined by subtracting 3degrees from the condylar twist angle.

Results of Ceramic on Ceramic Bearing Total Hip Arthroplasty Using Cemented Femoral Stem and Cementless Femoral Stem

PURPOSE: The purpose of this study was to evaluate the results of ceramic-on-ceramic bearing primary total hip arthroplasty (THA) using cemented femoral stems and cementless femoral stems. MATERIALS AND METHODS: We studied 59 cases (52 patients) of THAs using ceramic-on-ceramic bearing cemented femoral stems and 64 cases (58 patients) of THAs using ceramic-on-ceramic bearing cementless femoral stems. All THAs were performed between January 2004 and February 2005 and were followed up for more than 3 years. The clinical results were evaluated using the Harris hip score (HHS), WOMAC score, sense of discomfort, and thigh pain. Radiographic results were assessed with serial radiographs. RESULTS: The mean HHS improved from 62.7 points preoperatively to 92.4 points at the last follow-up in the cemented stem group and improved from 61.5 points to 91.8 points in the cementless stem group (p>0.05). And mean WOMAC score improved from 37.9 points to 7.0 points in the cemented stem group and from 38.5 points to 12 points in the cementless stem group (p<0.05). There were 5 patients with a sense of discomfort and 9 patients with thigh pain in the cementless stem group and no cases in the cemented stem group. There were no instances of acetabular loosening in either group. Subsidence of the cemented femoral stem was less than 1 mm in 57 cases and less than 2 mm in 2 cases. All cementless femoral stems acquired firm bony union. CONCLUSION: Ceramic-on-ceramic bearing THA using a cemented stem showed clinical results superior to those achieved using a cementless stem. Cemented THA is thought to be good for complementing the problems caused by the hardness of ceramic-on-ceramic bearings.

Early Loosening of Femoral Component after Primary Total Knee Arthroplasty : Report of 4 Cases

The mechanism of the loosening after arthroplasty is considered that micromotion makes a gap between implant and bone, the subsidence of implant and osteolysis around the implant. The loosening of femoral component after total knee arthroplasty(TKA) might be related to the improper support of posterior condylar area, the causes of which may be inaccurate osteotomy, improper cementing technique and poor bone quality, etc. The authors found four cases of flexed displacement and osteolysis around the femoral component after TKA. The types of implant were one case of PS type and three cases of High Flex PS type. Revision arthroplasty was done in three patients who had severe clinical symptoms with diffuse bone loss around the distal femur. We evaluated the mechanism of the early loosening by clinical and radiologic assessment of four patients.

Analysis of the Relationship between Posterior Cruciate Ligament Preservation and Femoral Component Sizein Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: How PCL preservation affects the selection of femoral component size in total knee arthroplasty. MATERIALS AND METHODS: One hundred and fifty-seven patients, two-hundred and twenty-two knees, underwent total knee arthroplasties with Scorpio(R). One hundred and eighteen knees underwent PCL-preserving procedures, and one-hundred and four knees underwent PCL-substituting procedures. For minimization of error, we performed soft tissue balancing and then bone cutting by a Linker system with certain posterior slope (< or = 3 degrees). We compared the sizes of the femoral components between the PCL-preserving and PCL-substituting procedures in order to determine how flexion gap differences affect femoral component sizes (Wilcoxon signed rank test). RESULTS: With a certain minimal posterior slope (< or = 3 degrees), the PCL-preservation procedure led to selection of a 2.4 mm smaller femoral component than the PCL substituting procedure (p<0.05). CONCLUSION: Selection of femoral component size was affected by PCL preservation, and the size of the femoral component was decreased in the PCL preservation group.

Anatomical Assessment of Distal Femur for Optimal Femoral Component Rotational Alignment in TKA / 대한정형외과학회잡지

PURPOSE: We evaluated the relationship among the various rotational reference axes of femoral component in TKA, and the potential change in rotational alignment when a posterior condylar axis (PCA) was used as a reference for different cartilage erosions between the medial and lateral posterior femoral condyles. MATERIALS AND METHODS: The study subjects included twenty male and twenty female volunteers. Axial MR image of the distal femur were used to measure the angles among the clinical transepicondylar axis (cTEA), surgical transepicondylar axis (sTEA), the PCA, and the AP axis. We then evaluated the difference in the amount of rotation between a normal and osteoarthritic model when the PCA was used as a rotational reference. RESULTS: The mean angle between cTEA and PCA was 5.4 degrees, and it was significantly greater in the female (6.5 degrees) than in the male group (4.3 degrees). The cTEA demonstrated a perpendicular relationship with the AP axis in both groups. The average angles between cTEA and sTEA were 3.2 degrees in the male group and 3.8 degrees in the female group. When we assumed complete erosion of the cartilage on the medial posterior condyle with preservation on the lateral side, the angles between the cTEA and PCA decreased by an average of 1.9 degrees in both groups. CONCLUSION: This study suggests that the two transepicondylar axes, which demonstrated greater than 3 degrees in angle-difference, should be defined clearly in scientific reports and in their application as rotational references in TKA. Some significant gender differences in the rotational profile were noted. When the PCA is used as a rotational reference, potential errors caused by the different amounts of cartilage erosion between the medial and lateral posterior condyles should be considered.

The Study of Anatomical Measurement of Distal Femur and Compatibility of Femoral Prosthesis in Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to provide the basic data for the anatomy of distal femur by real measurement, to determine the morphologic fit between the distal femur of Koreans and the femoral prostheses in total knee arthroplasty. MATERIALS AND METHODS: For 173 knees of 117 patients who underwent total knee arthroplasty, we measured the mediolateral width and the anteroposterior height of the distal femur during operation. RESULTS: The average mediolateral width of the distal femur was 68.4+/-4.3 mm, and the average anteroposterior height of the medial and lateral condyle were 59.0+/-4.7 mm and 60.8+/-4.0 mm respectively. the distal femurs of Koreans are smaller on average than the femoral prostheses used in Korea. The average ratio of height to width of the distal femur is 0.86+/-0.07, but the ratios of the five different kinds of femoral prostheses were not constant. So discrepancy between the ratio of the distal femur and the femoral prosthesis results in poor bony coverage. CONCLUSION: A more adequate femoral prosthesis is required to improve the compatibility to the distal femur. These results should contribute to the development of new model of femoral prosthesis for Koreans.

Treatment of Infected uncemented Total Hip Arthroplasty: Two-stage revision procedure by preserving well-fixed femoral components in four cases / 대한정형외과학회잡지

In infected uncemented hip arthroplasty, 4 cases which showed well-fixed femoral stem were managed by staged procedure. Thorough debridement, removal of acetabular socket and insertion of antibiotics impregnated cement spacer was done without removal of femoral stem. No recurrence of infection or loosening was developed after staged procedure and revisoin was performed after infection evidence disappeared. The interval between the two procedures was 4 months (3-6) on average. In Weber's criteria, all 4 cases were graded as having definitive cure of infection on both clinical and radiological criteria (Grade I) .

Fracture of the Femoral Component in Total Knee Arthroplasty Using Whiteside Ortholoc Prosthesis with Cement - Metallurgical Study by SEM and EDS / 대한정형외과학회잡지

The present study reports two cases of femoral component fracture using Whiteside Ortholoc prosthesis(Dow Corning Wright, Arlington, Tennessee) with cement. The causes of the fracture were investigated by radiological findings, prosthetic design and metallurgical study using scanning electron microscope(SEM) and energy dispersive spectrometer(EDS). Respectively, the findings from this study are summarized as follows. In X-ray study, one case had valgus 3 mechanical axis(normal: valgus 7 axis) while the other case had 10 tibial anterior slope(normal: 10 posterior slope). The medial side of femoral component fractured in both cases. The fracture site was in the junction between the posterior bevel and distal surface of the medial side of femoral component. The analysis of the prosthetic design showed that the Whiteside Ortholoc femoral stem was thinner, and shorter at the site of posterior bevel surface of the femoral stem than other TKA(Total Knee Arthroplasty) system. The metallurgical study by SEM showed that the crack was developed initially near the inner surface of fractured femoral component and was extended to the outer surface. Carbon particles were detected in the fractured femoral component by EDS. The findings imply that operating technique is very important especially during bone cutting and soft tissue balance in TKA. It is also proposed from this study that a minor design modification such as a thicker and longer Whiteside Ortholoc femoral component would be better and that the cast-iron ware of TKA system has to he produced by careful metallurgical process, that precludes the incorporation of any foreign material such as carbon particles.

Fracture of the Femoral Component in Whiteside Ortholoc Modular Total Knee ArthroplastyL: 2 Cases Reports

The breakage of component is rare in TKA and usually restricted to hinges and linked design. Occasionally fracture of metal tibial component has been noted, but fracture of the femoral component has been rarely reported and occurred to be a significaot problem in TKA. This study reports 2 cases of femoral component fracture using Whiteside Ortholoc total knee system and analyzes the cause of this phenomenon. One pahent, a 67 years old female who weighed 74kg, was performed 1ke left TKA using Whiteside Ortholoc g system with cement. The size of feraoral component was small plus, and small tibial component, 14mm tibial insert and 28mm pateBa were used, The medial site of femoeal component fractured at 38 months postoperatively. A second female patient, who weighed 68kg and was 64 years old at the time of surgery, had also the left TKA using a medium sized femoral component of Whiteside Ortholoc modular system with cement. The small-Ex large tibial component, 8rrun tibial insert were used, but did not replace the pateBa. Also at 37 mainths postaperatively the medial site of femoral compcnent fractured, Ail cases were revised with using a cemented P,F.C. Modular Total Knee System (Johnson k Johnson). All two cases were kactured at the junction between the posterior bevel md distal surface of the medial femoral condyle. The thickness and length of Whiteside Ortholoc femoral component are thinner and shorter at posterior bevel surface compared with other TKA systems. So it is encouraging that a minor design modification of Whiteside Ortholoe femoral component and also should be edueated for the prohibihon of excessive flexion of the knee joint after TKA.

Cemented Femoral Component with Centralizing Device : Is it Effective for Centralization and for Attainment of Optimal Cement Mantle Thickness ? / 대한정형외과학회잡지

To evaluate the effectiveness of centralizing device, three groups of patients on whom cemented total hip arthroplasty with three types of implant was performed respectively were analyzed and compared; SL stems without centralizing device were used in Group I, Interlok stems with central sleeve in Group II, and MS-30 stems with distal centralizer in Group III .The size of each group was 20. Cement mantle thickness, the amount of displacement of stem tip, and axis alignment of femoral stem on A-P radiograph checked at 2 weeks after operation were assessed. More optimal cement mantle thickness (3~6mm) was achieved in Group II (P=0.046) and Group III (P=0.01) than in Group I. Centralizing effect of the distal femoral stem in the intramedullary canal was significantly better (P<0.05) in Group III ( 4.55% ) than in Group I (11.60%) and Group II (12.35%). Neutral alignment of femoral stem was achieved in 15% of Group I, in 90% of Group II, and in 95% of Group III. Compared to stem without centralizing device, cemented femoral stem with distal centralizer resulted in 1) significantly more centralized distal femoral stem, 2) significantly more neutrally aligned femoral stem,and 3) significantly more optimal cement mantle thickness at zone V. Compared to stem without centralizing device, cemented femoral stem with central sleeve resulted in 1) significantly more neutrally aligned femoral stem, and 2) significantly more optimal cement mantle thickness at zone VI.

Analysis of Femoral cortical Indices in Cementless Femoral Stem / 대한정형외과학회잡지

Preperative radiologic indices, such as cortical index of Engh, morphological cortical index of Sportono and Romagnoli, canal flare index of Noble, and their relationship to the postoperative canal filling, femoral stem fitness, stability and clinical result at last follow up were analyzed in 111 hips of 96 patients treated with bipolar or total hip arthroplasty at the Department of Chthopedic Surgery, Korea University Hospital, between January 1985 and May 1993. The results obtained were as follows: 1. The cortical index had no correlations with age, metaphyseal filling and clinical result but isthmic filling was proportional to the cortical index. In femoral stem fitness and stability, most cases of press fit and optimal stability were obtained in group 3 and 4 that have thick cortex. 2. The morphological cortical index had no correlation with age, canal filling and clinical results. But it was proportional to the postoperative femoral stem fitness and stability. 3. The canal flare index had no correlation with age. The metaphyseal filling was increased in the stove piped canal group(less than 3.0 canal flare index), but isthmic filling was increased in normal canal group(3.0-4.7 canal flare index). The most cases of press fit and optimal stability were obtained in normal canal group. More satisfactory clinical results were obtained in nomal canal group. Above results suggest that straight type of cementless femoral component could get better press fit fixation, postoperative stability and more satisfactory clinical results in the cases of cortical index larger than 2.0, mophological cortical index larger than 2.7 and canal flare index larger than 4.0 but metaphyseal filling is unsatisfactor.