INTRODUCTION. Golf is considered low-impact sport, but concerns exist about whether golf swing can be performed in safe manner after THA. The purpose of this study was to clarify dynamic hip kinematics during golf swing after THA using image-matching techniques. METHODS. This study group consisted of eight right-handed recreational golfers with 10 primary THAs. Each operation was performed using a posterolateral approach with combined anteversion technique. Nine of ten polyethylene liners used had elevated portion of 15°. Continuous radiographic images of five trail and five lead hips during golf swing were recorded using a flat panel X-ray detector (Fig. 1) and analyzed using image-matching techniques (Fig. 2). The relative distance between the center of cup and femoral head and the minimum liner-to-stem distance were measured using a CAD software program. The cup inclination, cup anteversion, and stem anteversion were measured in postoperative CT data. Hip kinematics, orientation of components, and cup-head distance were compared between patients with and without liner-to-stem contact by Mann-Whitney U test. RESULTS. At the top of backswing, lead hips showed 26 ± 11° ER, and trail hips showed 24 ± 19° IR. At the end of follow-through, lead hips showed 24 ± 19° IR, and trail hips showed 24 ± 12° ER. The mean cup inclination and anteversion, stem anteversion, and combined anteversion were 40 ± 5°, 18 ± 11°, 33 ± 14°, and 50 ± 8°, respectively. The minimum liner-to-stem distance showed the smallest value of 3 ± 4 mm at the maximum ER. Bone-to-bone and bone-to-implant impingements were not observed in all hips at all phases. The liner-to-stem contact was observed in four hips with elevated liners (two trail and two lead hips; Fig 3). Patients with elevated liner-to-stem contact demonstrated significantly (p < .05) larger maximum ER and larger cup anteversion than patients without contact. The mean cup-head distance was 0.9 ± 0.5 mm of translation. No significant difference was found in the flexion/extension and adduction/abduction at the maximum ER, cup inclination, combined anteversion, and cup-head distance between patients with and without contact. DISCUSSION. Golf swing produced approximately 50° of axial rotations in both lead and trail hips after THA. The mean cup-head distances showed less than 1.0 mm, and there was no significant difference between patients with and without neck-liner contact. Therefore, we consider that dynamic stability without excessive hip rotations or subluxation was demonstrated during golf swing. Despite no evidence of component malpositioning, elevated liner-to-stem contact was observed in 40% of hips with significantly larger ER and cup anteversion. Because the liner-to-stem contact may be a concern with regard to the long-term prognosis following THA, further attention must be given to the anteversion of the components and the use of elevated liner at the time of surgery. To view tables/figures, please contact authors directly

Background:. The axis of the fibula in the sagittal plane are known as a landmark for the extramedullary guide in order to minimize posterior tibial slope measurement error in the conventional total knee arthroplasty (TKA). However, there are few anatomic studies about them. We also wondered if the fibula in the coronal plane could be reliable landmark for the alignment of the tibia. This study was conducted to confirm whether the fibula is reliable landmark in coronal and sagittal plane. Methods:. We evaluated 60 osteoarthritic knees after TKA using Athena Knee (SoftCube Co, Ltd, Osaka, Japan) 3-D image-matching software. Angle between the axis of the fibula (FA) and the mechanical axis (MA) in the coronal and sagittal plane were measured. Results:. The mean angle between the FA and MA was 0.86 ± 2.0° of varus in the coronal plane (range 6.0° of varus to 4.2° of valgus) and 2.6 ± 2.3° of posterior inclination in the sagittal plane (range 6.8° of posterior inclination to 2.8 of anterior inclination), respectively. The percentage of subjects in which FA was within 3° of the MA was 77% in the coronal plane and 58% in the sagittal plane, respectively. Conclusions:. The FA used as a landmark for the alignment of the tibia in the conventional TKA differed from MA relatively in this study, and not be used safely if the differences are considered

Introduction. Increased long-term survival of TKA is becoming more important. Several studies have confirmed that optimal positioning and alignment of prosthetic components is crucial for the best long-term results. Therefore, the purpose of the current study was to compare the postoperative alignment and sizing of femoral prosthesis among patients performed by 3 different navigation systems. Methods. Twenty patients who underwent primary TKA (E. motion; B. Braun Aesculap, Tuttlingen, Germany) using a CT-free navigation system (OrthoPilot v 4.2) by modified gap technique were enrolled in this study. The results of this study group were retrospectively compared with those in a control group of 20 matched-paired posterior stabilized TKAs (Triathlon;Stryker; Mahwah, NJ, USA) which were using another CT-free navigation system (Stryker Navigation System) by measured technique and 20 matched-paired posterior stabilized TKAs (Press-fit Condylar prosthesis; DePuy, Tokyo, Japan) using CT-based navigation system (VectorVision) by measured technique. Several parameters were evaluated for each patient using Athena Knee (Softcube Co, Ltd. Osaka, Japan), 3-D image-matching software. The coronal component angles and sagittal component angles were measured in relation to mechanical axis (MA). In addition, axial femoral component angle was measured in relation to surgical epicondylar axis (SEA) and axial tibial component angle was measured in relation to Akagi line. Results. (Coronal plane alignment). The coronal femoral component angle (varus) was 1.3° ± 2.7° in the Orthopilot group, 1.1 ± 1.5° in the stryker group and 0.21° ± 2.2°in VectorVisioin group with no sigificant difference. The coronal tibial component angle (varus) was 0.7° ± 2.0° in the Orthopilot group, −0.50° ± 1.4° in the stryker group and −1.0° ± 1.2° in VectorVision group with no significant difference. (Sagittal plane alignment). The sagittal femoral component angle (flexion) was 2.7° ± 2.2° in the Orthopilot group, 3.3° ± 2.4° in the stryker group and −0.2° ± 2.9°in VectorVisioin group. The sagittal femoral component angle in VectorVison group is significantly smaller than that in the Orthopilot group and that in the Stryker group. The sagittal tibial component angle (posterior slope) was 4.7° ± 1.9° in the Orthopilot group, 2.6° ± 1.5° in the stryker group and 2.8° ± 1.4° in VectorVision group. The posterior slope was aimed at 5°in Orthopilot group and 3°in stryker group and VectorVision group. Accuracy among 3 groups is no significant difference. (Axial component angle). The axial femoral component angle (external rotation) was 2.2° ± 1.9° in the Orthopilot group, 1.2° ± 1.5° in the stryker group and −0.9° ± 2.0°in VectorVisioin group. The axial femoral component angle in Orthopilot group was significantly more external than that in the stryker group and that in the VectorVision group. The axial tibial component angle (external rotation) was 2.4° ± 5.0° in the Orthopilot group, 2.6° ± 5.5° in the stryker group and 2.0° ± 4.2° in VectorVision group with no differnence. Discussion and Conclusion. We performed primary TKA by 3 different navigation systems and analyzed alignment of component. Accurate alignment was obtained in all 3 different navigation systems. However surgeons should take into account the features in each navigation