The purpose of this study in to investigate the role of infrapatellar fat pad on primary total knee arthroplasty. We evaluated 100 patients who had been undergone TKA from August 2002 to July 2003, with open box posterior substituting femoral component implant (Scorpio PS Knee^™). The study was performed prospectively and randomly allocated. We divided two groups. Group 1 (50 knees) was preserved infrapatellar fat pad and repaired fad at wound closure. Group 2 (50 knees) was excised infrapatellar fat pad as possible and repaired only joint capsule. We analyzed and compared clinical results of Knee Society knee (KS) score, function score, patellar score and Insall-Salvati ratio in both groups. The complications of each group were evaluated. Patients were followed up for mean 40 months(17~52 months).

Mean KS score was 91.9 (91.94±5.58) in Group 1 and 90.9(90.92±6.38) in Group 2. Mean function score was 81.6(81.64±13.18) in Group 1 and 83.7(83.79±17.71) in Group 2. Mean patellar score was 29.9(29.89±9.10) in Group 1 and 27.9(27.90±1.80) in Group 2. And mean patellar height as Insall-Salvati ratio was 1.19(1.19±0.17) in Group 1 and 1.23(1.23±0.11) in Group 2. The differences between the Group 1 and Group 2 in all of index were statistically insignificant. In complications, 2 cases of recurrent hemarthrosis were observed in Group 1 patients.

We concluded The difference of clinical outcomes whether infrapatellar fat pad was excised or not were statistically insignificant. However, preservation of infrapatellar fat pad on open boxed PS TKA showed unique complications such as recurrent hemarthrosis which might be caused by fat pad adhesion to intercondylar notch. We propose that infrapatellar fat pad on primary PS TKA with open box design would like to be excised for prevention of unique complications.

INTRODUCTION. Femur is one of the bones in humans that exhibit ethnic, racial, and gender difference. Several basic and clinical studies were conducted to explore these variations. Clinical anthropological studies have dealt with the compatibility of femoral prostheses and osteosythesis and materials with the femur. If there is a misalignment between the Total Knee Arthroplasy (TKA) femoral comportment installation position, Range of Motion (ROM) failure and several problems may arise. The aim of this study was to evaluate anterior bowing of the Japanese femur and to assess the adequacy of TKA femoral comportment installation position. METHODS. We analyzed 76 normal Japanese and 97 TKA patients. (June 2014-June 2015) The average age of the normal subjects was 62.0±20.90 (24–88) years old and the average of TKA subjects was 73.6±7.9 (53–89) years old. First we defined and measured the anterior curvature and the posterior condylar offset (PCO) in normal japanese femurs. Then in TKA patients we set the implant as same angle of the component. Third, we measured the post operative anterior curvature and PCO. Then calculated the anterior curvature difference and PCO differences and preformed statistical analysis with ROM. RESULTS SECTION. The average of anterior curvature in normal subjects was 7.87±6.60 degrees. Among 97 TKA patients, pre-operative anterior curvature was 7.58±0.16 degrees. Further, the angle of component which was set the post operatively was 7.32±0.25. The average of Anterior curvature difference and PCO differences had correlation with ROM. DISCUSSION. Gilbert reported that caucasian femurs are straight compared to asian femurs. Chinese and Japanese showed different anterior curvature because of different life style. The chalenges are when operating on different ethnic patients, Orthopedic Surgeons consider many factors. Previous studies yielded different suggestions for the ideal point of entry. We suggest difference between the curves of the femurs should be considered for TKA femoral comportment installation position. SIGNIFICANCE. 1)Our results gave an anatomical characteristics of Japanese femur. 2)These data will give clinical indication for TKA femoral comportment installation position

Objectives. To evaluate the clinical and radiographic outcomes of total knee arthroplasty using Vega® Knee System (B Braun-Aesculap, Tuttlingen, Germany) [Fig. 1] designed to allow high flexion by shortening the length of posterior condylar flange of femoral component after at least 2 year and to assess the occurrence of periprosthetic osteolysis and loosening at final follow-up. Materials and Methods. Of the patients who underwent total knee arthroplasty using Vega® Knee System between April 2011 and May 2013, 40 patients (46 knees) were enrolled. The mean age of the patients at the time of surgery was 72.3 years and the mean follow-up period was 29.4 months. Clinical parameters, including Knee Society Knee score, Knee Society Function score, maximal flexion and range of motion were evaluated. Relationship between postoperative maximal flexion and radiographic factors including the posterior tibial slope, the femoral condylar offset and the change of the posterior flange length of femoral condyle was analyzed. Also, the occurrence of periprosthetic osteolysis and loosening was assessed. Results. The mean preoperative flexion contracture was 4.3° which was reduced to 1.1° at the final follow-up (P < 0.05). The mean preoperative maximal flexion was 121.6° which was increased to 132.7° at the final follow-up (P < 0.05). The mean preoperative range of motion was 122.8° which was increased to 130.5° at the final follow-up (P < 0.05). The mean preoperative knee score and function score were 54.2 and 46.1. At the final follow-up, the mean knee score and function score were improved to 90.2 and 78.6 (P < 0.05). The post operative posterior tibial slope, femoral condylar offset and the change of the posterior flange length of femoral condyle showed no significant relationship with the postoperative maximal flexion angle. (posterior tibial slope; R=0.241, p=0.94 / femoral condylar offset; R=−0.271, p=0.167 / posterior flange; R=−0.074, p=0.623). The periprosthetic osteolysis of the femoral component occurred in two cases, but loosening did not occur at the final follow-up. Conclusions. Total knee arthroplasy using Vega® Knee System provided satisfactory maximal flexion at minimum 2 year follow-up and there was no the periprosthetic loosening. And, there was no significant relationship between postoperative maximal flexion and radiographic factors including the posterior tibial slope, the femoral condylar offset and the change of the posterior flange length of femoral condyle. To view tables/figures, please contact authors directly

Periprosthetic fractures around Total Knee Arthroplasty are potentially devastating complication to both the patients and the surgeons. The reported prevalence of supracondylar femoral fractures following Total Knee Replacement has ranged from 0.3 to 2.5 percent. The complication rates of various treatment modalities reported in literature varies from 25 to 70 percent. Aim: The purpose of this study is to evaluate the outcome of Antegrade Nailing and Wire fixation in Supra-condylar femoral periprosthetic fractures. Material & Methods: Seven patients who sustained complex distal femoral fractures above Total Knee Arthroplasty all treated by New technique of Ante-grade intramedullary Nailing and intramedullary bi-wire fixation through greater trochanteric approach without opening the distal femur were retrospectively evaluated. Results: All the patients demonstrated uncomplicated postoperative follow-ups and returned to weight bearing between 2 and 3 months. The average age of patient was 70 (55–90) years. All fractures healed in a satisfactory alignment in average duration of 12.6 weeks. There was no wound infection, loss of reduction or implant failure. The average range of movement of knee was 86 degrees. Conclusion: The Antegrade Nail with Wires is a simple & effective method of treating displaced periprosthetic fractures proximal to Total Knee Arthroplasy. This involves less soft tissue dissection, less operative time and satisfactory bony healing even in poor quality bones while maintaining adequate range of movements of the knee

Introduction. Revision total knee arthroplasy (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone resorption beneath metal block augmentation has been still reported and little information about the reasons of the occurrence of bone resorption is available. The aim of the current study is to identify a possibility of the potential occurrence of bone resorption beneath metal block augmentation, through evaluation of strain distribution beneath metal block augmentation in revision TKA with metal block augmentation, during high deep flexion. Materials and Method. LOSPA, revision TKA with a metal block augmentation (Baseplate size #5, Spacer size #5, Stem size Φ9, L30, Augment #5 T5) was considered in this study. For the test, the tibia component of LOSPA was implanted to the tibia sawbone (left, #3401, Sawbones EuropeAB, Malmö, Sweden), which was corresponded to a traditional TKR surgical guideline. The femoral component of LOSPA was mounted to a customized jig attached to the Instron 8872 (Instron, Norwood, MA, USA), which was designed specially to represent the angles ranged from 0° to 140° with consideration of a rollback of knee joint (Figure. 1). Here, a compressive load of 1,600N (10N/s) was applied for each angle. Strain distribution was then measured from rossete strain gauge (Half Bridge type, CAS, Seoul, Korea) together (Figure 1). Results and Discussions. The strain distribution on the cortical bone of the tibia was shown in Figure 2. The results showed that the strains on the posterior region were gradually increased from extension to high deep of the knee joint and generally larger than the other regions. In contrast to the results on the posterior region, the strains on the medial region were gradually decreased after 60° or 90° flexion position and relatively lower than the other regions. Particularly, the strains on the medial region were generally lower than 50–100 µstrain, which is known as critical value range able to inducing bone resorption, during high deep flexion. This fact indicate that a possibility of the potential bone resorption occurrence in revision TKA used with a metal block augmentation may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. This study may be valuable by identifying for the first time a possibility of the potential bone resorption occurrence through evaluation of the strain distribution beneath metal block augmentation in revision TKA used with a metal block augmentation during high deep flexion. Conclusion. A possibility of the potential bone resorption occurrence in revision TKA used with a metal block augmentation may be dependent on loading patterns applied on the knee joint related to personal lifestyle history. Particularly, it may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. Acknowledgements. This study was supported by a grant from the New Technology Product Evaluation Technical Research project, Ministry of Food and Drug Safety (MFDS), Republic of Korea

Arthrodesis is used most commonly as a salvage procedure for failed total knee arthroplasty (TKA). For successful arthrodesis, a stable fusion technique and acceptable limb mechanical alignment are needed. Although the use of intramedullary alignment rods might be helpful in terms of achieving an acceptable limb mechanical axis, fat embolism and intramedullary dissemination of an infection or reactivation of latent infection might occur in failed TKA cases. However, computer-assisted surgery allows precise cuts to be made without breaching medullary cavities. Here, the authors describe a case of knee arthrodesis performed by computer navigation and the Ilizarov method in a patient with a past history of infection. A 45-year-old man visited our hospital with failed total knee arthroplasy. Fortunately, even though infection was treated by debridement with component retention, mild heating was present over the knee, but ESR(erythrocyte sedimentation rate) and CRP(C-reactive protein) were within normal ranges. X-ray showed subsidence of the femoral component and a radiolucent line around the femoral component. Arthrodesis was planned for this patient due to disabling pain, a long-lasting severe functional deficit, failure of the primary TKA for ankylosed knee, and the patient’s poor economic status and his strong desire for arthrodesis. The computer navigation surgery system and the Ilizarov method were used for two reasons. The first reason was that the patient had a past history of infection. At pre-operative evaluation, even though ESR and CRP levels were within normal range, we could not completely rule out the possibility of latent infection due to suspicious findings such as long lasting disabling knee pain, mild heating over the knee, severe osteolytic radiographic changes around the femoral component. In that situation, inserting an IM rod to achieve acceptable mechanical alignment might have reactivated and disseminated a possible latent infection to the femoral or tibial medullary canals. The second reason was that we wanted to reduce the possibility of fat embolism by using computer navigation without instrumentation within the medullary canal. A CT-free, wireless computer navigation system was applied, with trackers fixed to the femur and tibia and no requirement for the use of an IM rod with component retention. Navigated femoral and tibial bone resections were then performed using Stryker software. The femoral resection was conducted at 0° of flexion to the sagittal axis, and the tibial resection at 7 ° of flexion to the sagittal axis. Arthrodesis was held in proper axial and rotational alignment with bone surfaces compressed together. Finally, knee arthrodesis was completed using the Ilizarov method. Based on our experience of the described case, we believe that arthrodesis for failed TKR, especially failure secondary to intraarticular infection, can be considered as another indication for computer navigation

Patellar maltracking after total knee arthroplasy (TKA) introduces complications such as anterior knee pain and patellar subluxation, generally due to prosthetic component malallignment in both tibiofemoral (TF) and patellofemoral joints. It is still debated if it is necessary to resurface the patella, which would better adapt the patellar articular surface to the prosthetic femoral troclea with a prosthesis, but also result in possible bone fractures. In this study, an in-vitro analysis is presented in order to identify differences between intact and TKA patellar tracking with and without patellar resurfacing and to show how much the latter is similar to intact knee patellar tracking. Three fresh-frozen amputated legs with knees free from anatomical defects and with intact joint capsule, collaterals and quadriceps tendon were analyzed using the Stryker knee navigation system (Kalamazoo, MI-USA). Landmark digitations were used to define anatomical frames for femur, tibia and patella. Manually driven TF flexions, from 0 to 140, were performed under conditions of no load and of 10 kg on the quadriceps, with intact knee and TKA with patella resurfaced and not. TF flex/extension, intra/extra rotation, ad/abduction were calculated according to a standard convention. Patellar flex/extension, medial/lateral tilt, rotation and shift were calculated according to a recently proposed articular convention. Since more repeatable, results relative to trials under 10 kg are reported. Intact knee: 4 abduction; considerable intra rotation (from 16 to 4), followed by continuous extra rotation starting at 30 TF flexion; linear increase in patellar flexion (from 20 to 110); initial medial patellar rotation (from 12 to 8), followed by medial rotation starting at 60 TF flexion; initial lateral patellar tilt (from 4 lateral to 4 medial), followed by medial tilt starting at 70 TF flexion; initial 6 mm lateral patellar shifts from 0 to 80 TF flexion, followed by 4 mm medial shift. TKA knee: small differences in ad/abduction between intact and TKA knees, both with and without resurfaced patella; slight initial extra rotation, followed by continuous intra rotation starting at 20 TF flexion; linear increase in the flexion of the patella, both resurfaced and not, close to the that of the intact knee; patellar rotation more lateral than in the intact knee; patellar tilt without resurfaced patella closer to the intact knee one; 6 mm lateral patellar shift, likely accounted for the surgical technique. Slightly more than TKA with resurfaced patella, TKA with non resurfaced patella flexes nearly like the intact knee. The closeness in values of patellar flexion and tilt represents a proof of the closeness in behavior of not resurfaced patella in TKA to the patella in the intact knee