• Journal of Biomedical Engineering Research
• /
• v.19 no.1
• /
• pp.53-58
• /
• 1998

This study examined the distribution of bone mineral density(BMD) and the von Mises stress in the patella. The BMD of eighteen patellae were determined by using quantitative computed tomography and imaging analysis software. It was found that the BMD of the patella varied with location. BMD values were largest at the superior and lateral regions and decreased inferiorly and medially. This distribution appeared to correspond to the organization of trabeculae within the patella. A two-dimensional finite element analysis was performed on each patella. It was also found that the maximum von Mises stress in the patella occurred along the cortical shell on the non-articular surface. The trabecular von Mises stress existed in the posterior region of the patella. These findings demonstrated the potential for finite element studies in vivo. Further, such studies may lead to the development of custom-made, patient-specific patella prostheses.

• Knee surgery & related research
• /
• v.30 no.4
• /
• pp.334-340
• /
• 2018

Purpose: The purposes of this study were to compare clinical results after total knee arthroplasty (TKA) using the Attune and PFC Sigma knee designs and to investigate whether the use of the Attune prosthesis increased the risk of patellar injury in Asian patients. Materials and Methods: Three hundred knees that underwent TKA using Attune (group A) were compared to 300 knees that underwent TKA using PFC Sigma (group B). The Knee Society Knee Score (KS) and Function Score (FS), and range of motion (ROM) were compared. The residual patellar thickness was compared to evaluate the risk of patellar injury. Results: The postoperative KS and ROM of group A were better than those of group B (93.1 vs. 88.8, p<0.001 and $131.4^{\circ}$ vs. $129.0^{\circ}$, p=0.008, respectively). The postoperative FS did not differ significantly between the two groups (80.9 vs. 78.7, p=0.427). The residual patella was thinner in group A (14.8 mm vs. 15.7 mm, p=0.003), which made up a higher proportion of the high-risk group for patellar fractures with a residual thickness of <12 mm (7.5% vs. 2.1%, p=0.003). Conclusions: TKA using the Attune prosthesis provided more favorable clinical results than TKA using PFC Sigma. However, the risk of injury in the residual patella was increased with use of the Attune prosthesis in Asian patients.

• The Journal of the Korean bone and joint tumor society
• /
• v.2 no.1
• /
• pp.8-17
• /
• 1996

The purpose of this study is a comparative evaluation of range motion, especially extension deficit between the group of total patellectomy and that of intact patella, after reconstruction of the patellar tendon in the prosthetic replacement of a proximal tibia. Between 1990 and 1994, 15 patients who had a primary malignancy on proximal tibia were operated on. All patients were evaluated clinically and radiographically. Two patients were excluded because one had a deep infection treated with arthrodesis of the knee and the other was a composite allograft. The mean follow-up of the 13 patients was 27 months(15-47), including 10 osteosarcomas, 1 chondrosarcoma, 1 malignant fibrous histiocytoma and 1 malignant giant cell tumor. Eleven patients had a resection of the proximal tibia and 2 had an extracapsular total knee resection with distal femur. Reconstruction of the defect was done in 8 cases with a custom-made Link Endo-Model Total Rotation Knee Joint Prosthesis, and in 5 with How Medica Modular Resection System (HMRS). We used two methods to reconstruct the ligamentum patellae. Fixation of the patellar tendon to the prosthesis only with suturing and/or stapling(group SS) was done in 7. Transposition of gastrocnemius muscle to enhance fixation and to cover the prosthesis(group TG) was done in 6. Regardless of fixation methods, total patellectomy was done in 5 either to lengthen the patellar tendon or to make primary skin closure easier or for both. In 8 cases, patella was left intact or resurfaced with polyethylene prosthesis. Active extension was measured while the patient was in a sitting position. There is no statistically meaningful difference in terms of extension deficit (Wilcoxon rank test, p=0.8800) between patellectomy group and intact patella group, and between group of fixation only with suturing and that of gastrocnemius transposition. Two cases of extension deficit over 30 degree were seen in group SS and in the group of intact patella. Conclusively, total patellectomy could be an option without increasing the risk of extension deficit when primary skin closure is difficult or patellar tendon is a little bit short to be fixed. There is no rating in the Enneking system of functional evaluation that this finding into consideration.

• Journal of Veterinary Clinics
• /
• v.33 no.5
• /
• pp.295-299
• /
• 2016

A 2-year-old, 1.94 kg spayed female Toy Poodle was referred for revision surgery for patellar reluxation following surgery for bilateral medial patellar luxation (MPL). Intermittent non-weight-bearing lameness of the right hindlimb and weight-bearing lameness of the left hindlimb were evident on general inspection. A physical examination revealed that there was a bilateral grade 4 MPL. On radiographs, the medial and lateral trochlear ridge was bilaterally worn out. Patellar groove replacement (PGR) was performed in two stages to replace the bilateral femoral trochlea that had a severely worn out groove. Corrective femoral osteotomy with increasing anteversion angle, tibial tuberosity transposition, medial releasing, lateral imbrications and PGR were performed on the right hindlimb. Six months after surgery on the right hindlimb, a PGR prosthesis was positioned medially on the frontal plane and tibial tuberosity transposition and lateral imbrications were performed on the left hindlimb. Two weeks after surgery, reluxation of the patella occurred on the left hindlimb. The tibial tuberosity transposition was performed to realign the patella more laterally than the previous surgery, and a patellar sling was applied. Two years after the last surgery, the patient showed no pain on the stifle joint and satisfactory weight-bearing ambulation. Reluxation did not recur. PGR maybe a successful treatment for dogs with iatrogenically damaged and/or worn out patellar grooves.

• Physical Therapy Korea
• /
• v.3 no.1
• /
• pp.65-72
• /
• 1996

The purpose of this study was to introduce rotation-plasty procedure and prosthetic ambulation training. The recent development of chemotherapy and diagnostic facility have permitted the orthopaedic surgeons to try limb saving procedures rather than amputations for the treatment of the malignant bone tumors. If the tumors around the knee joint were treated by mid-thigh amputation or hip disarticulation, it would impose the client with a great handicap for rehabilitation. Rotation-plasty procedure was first done by Borggreve, in 1930 for the congenital short femur. Recently this procedure was used a malignant bone tumor at the distal femur by Kotz and Salzer in 1982. In spite of its cosmetic problem of the distal stump, this procedure has the great functional advantage of converting the above-knee amputation to the below-knee amputation. The inverted foot was also good to control the prosthesis as a below-knee stump and heel functioned as a patella to support the body weight. This 15 years old girl case was had rotation-plasty due to osteosarcoma of the distal femur with 3rd postoperative chemotherapy, and admitted to Yonsei rehabilitation hospital for prosthetic ambulation training. Then, the case had excellent functional results of prosthetic ambulation training with rotaion-plasty after 3 months.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.7 no.1
• /
• pp.39-44
• /
• 2014

The patellar clunk syndrome is one of the patellofemoral complication, caused by formation of the fibrous nodule at the suprapatellar region after total knee arthroplasty. The symptom involves painful catching, crepitus and clunk during knee extension. It has been mainly but not exclusively associated with the posterior stabilized total knee system. The fibrous nodule is entrapped in the femoral intercondylar notch of the femoral component during flexion and as the knee is extended, it displaces back to the trochlear groove abruptly and the typical symptoms occur. The risk of developing this complication is primarily related to the design of the femoral component and higher incidence was noted with earlier designs of posterior stabilized knee prosthesis. Modifications have been made to the femoral component to optimize the kinematics of the patellofemoral joint and thereby reduced the incidence of patellar clunk syndrome but did not eliminate the problem completely. Clinical examination is the gold standard of diagnosis and imaging study has been used as a possible adjunct to diagnosis. Especially ultrasonography is an imaging modality, which can be easily performed to detect the fibrous nodule on the quadriceps tendon. We report a case of patellar clunk syndrome which was diagnosed with ultrasonography.