PS-TKA with more than 10degrees of Preoperative Posterior Tibial Slope

PURPOSE: We wanted to evaluate the effects of a preoperative posterior tibial slope of more than 10degrees on the extension gap and patellar height during posterior substituted total knee arthroplasty. MATERIALS AND METHODS: One hundred ten posterior substituted total knee arthroplasties were divided into group I (more than 10degrees of preoperative posterior tibial slope, n=56) and group II (less than 10degrees of slope, n=54). Each group was evaluated to compare the frequency of additional distal femoral resections due to an insufficient extension gap and the correlation with the decrease of the patellar bone height. RESULTS: In each group, the preoperative tibial slope was 12.77degrees (+/-3.22degrees) vs. 6.72degrees (+/-2.58degrees), respectively (p=0.000) and the decrease of the posterior slope was 10.74degrees (+/-3.54degrees) vs. 4.78degrees (+/-2.66degrees), respectively, (p=0.000). The frequencies of additional distal femoral resection were 54.5% vs. 46.1%, respectively, (p=0.448) with flexion contracture and 11.8% vs. 34.1%, respectively, (p=0.022) without flexion contracture. The decrease of the patellar bone height was 0.35 (+/-4.79) mm vs. 1.99 (+/-4.78) mm, respectively, (p=0.075). There was weak correlation between the decrease of the patellar bone height and the decrease of the posterior tibial slope (r=-0.253, p=0.016). CONCLUSION: In the group having more than 10degrees of preoperative posterior tibial slope without flexion contracture, the decrease of the posterior tibial slope had to be considered as one of the factors that affected making the extension gap significantly greater during the gap technique and to preserve the patellar bone height.

Effect of Decreasing Tibial Posterior Slope on the Extension-Gap during PS-TKA

PURPOSE: To evaluate the effect of decreasing tibial slope on extension gap during posterior stabilized total knee arthroplasty. MATERIALS AND METHODS: One hundred and ten cases of total knee arthroplasty which were done with posterior stabilized implant were included and we divided those into Group I; having flexion contracture (n=35) and Group II; no flexion contracture (n=75), and from each group, we evaluated the relationship between degree of decreased angle of tibial slope and frequency of additional resection of distal femur which was done for compensating insufficient extension gap during total knee arthroplasty and compared frequencies of additional distal femoral resections between 2 parts having more and less degree of decreased angle of tibial slope. RESULTS: In Group I and II, tibial slope decrease were 8.7degrees, 7.4degrees (p=0.145) and frequencies of additional resection were 51.4%, 24% (p=0.005) in average. Comparing 2 parts having more and less degree of decreased angle of tibial slope in each Group, frequencies of additional resection were 44.4%, 58.8% (p=0.505) and 13.2%, 35.1% (p=0.032). CONCLUSION: During posterior stabilized total knee arthroplasty, especially having no preoperative flexion contracture, decreasing tibial slope can be considered as a factor influencing on extension gap by removing greater anterior bone and the estimation of predictable tibial slope decrease through preoperative radiologic findings can be helpful in creating equal flexion and extension gaps.

The Effect of Patellar Position on the Flexion Gap in Total Knee Arthroplasty

PURPOSE: The aim of this study was to investigate the relationship between eversion or reduction of patella and the heights of the extension or flexion gaps. MATERIALS AND METHODS: Measurements of the heights of the extension and flexion gaps were obtained during 32 primary posterior-stabilized total knee arthroplasties in 25 osteoarthritic patients. A tensor device was introduced after femoral and tibial bony resections while putting the knees flat on the operating table to measure the extension gaps in the medial and lateral compartments, respectively. The knee was flexed 95 degrees, and the tensor was introduced to measure the flexion gaps in the same manner. A calibrated torque wrench permitted the application of the force of about 113.4N.cm both in extension and in flexion in right knee, and of about 152.4N.cm both in extension and in flexion in left knee. RESULTS: The average height of the extension gap with everted patella was 20.9+/-2.6mm medially and 23.6+/-2.5 mm laterally, respectively. The average height of the extension gap with reduced patella was 21.0+/-2.6mm medially and 23.7+/-2.4mm laterally, respectively. The average height of the flexion gap with everted patella was 20.7+/-2.5mm medially and 23.2+/-2.8mm laterally, respectively. The average height of the flexion gap with reduced patella was 22.1+/-2.3mm medially and 24.2+/-2.8mm laterally, respectively. After reducing the patella, the flexion gap height increased an average 1.4+/-1.1(range: 0~4)mm and 1.0+/-1.2(range: -1~3)mm in the medial and lateral compartments, respectively. CONCLUSION: The height of flexion gap would be increased by reducing the patella from everted position in posterior- stabilized total knee arthroplasty for the patient with good preoperative flexion. The flexion gap must be observed not with everted patella but with reduced patella to determine whether it appears symmetric and balanced.

Effects of a Posterior Cruciate Ligament Resection on the Flexion-Extension Gap in Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: To assess the effects of a posterior cruciate ligament resection on the tibiofemoral joint gap in total knee arthroplasty. MATERIALS AND METHODS: The effect of a PCL resection on the tibiofemoral joint gap was analyzed prospectively in 58 patients (69 knees) who had undergone TKA between May 2003 and April 2006. The knee was exposed using a modified subvastus approach. The medial soft tissue was released and a tibial cutting was made first. The tibial insertion of a PCL was protected during the tibial resection by inserting a thin osteotome in front of the posterior spine. An extension and flexion gap were measured using a balancer/tensor device (Stryker Howmedica Osteonics(R), Allendale, NJ, USA) under manual maximal stress before and after the PCL resection. The change of the joint line and the posterior inclination on preoperative and postoperative lateral roentgenograms was also assessed. RESULTS: After the PCL resection, the flexion gap and extension gap increased by an average of 3.6+/-1.5 mm and 2.0+/-1.0 mm, respectively. Although the PCL resection resulted in an increasing a flexion gap and extension gap, the increase in the flexion gap was larger than that of the extension gap by 1.6 mm. CONCLUSION: A PCL resection resulted in an increase in the flexion and extension gaps by 3.6 mm and 2.0 mm, respectively. Therefore, a PCL resection would be a good alternative method for controlling the flexion-extension gap in TKA.

The Relationship between Flexion-Extension Gap and Clinical Results in Total Knee Arthroplasty

PURPOSE: To evaluate the relationship between flexion-extension gap discrepancy and clinical results in total knee arthroplasty (TKA). MATERIALS AND METHODS: We evaluated the clinical results of 38 knees, which were performed TKA between March 2003 and June 2003, and followed up for at least 2 years. We divided all cases by the difference of medial and lateral joint gap in flexion and extension. Group A was no flexion-extension gap difference(17 cases) and group B was different gap(21 cases). We evaluated Knee Score, Function Score, range of motion and radiologic results RESULTS: The difference of group B was less than 2mm. In Knee Score and function score, Group A improved from preoperative 50.1 and 45.0 to the last follow up to 95.6 and 95.9, and those of Group B improved from 48.2 and 45.2 to 96.9 and 91.4. There was no statistical difference between two groups(p>0.05). Flexion angle of Group A increased from preoperative 108.2 degree to the last follow up 115.3 degree. That of Group B increased from preoperative 101.9 degree to the last follow up 113.6degree. But, there was no statistical difference between two groups(p>0.05). 2 cases of recurrent hemarthrosis were in Group B. CONCLUSION: We got good clinical results by flexion-extension gap difference within 2 mm. But long term followed up was needed.

Gap Discrepancy in Posterior Cruciate Ligament-Sacrificing Total Knee Joint Arthroplasty

PURPOSE: To evaluate the effects of PCL (posterior cruciate ligament) resection on the flexion and extension gap during TKA (total knee joint arthroplasty). MATERIALS AND METHODS: From December 2002 to August 2003, we quantitatively measured and ana-lyzed prospectively the flexion and extension gap before and after PCL resection during TKA in 26 cases among 23 patients of osteoarthritis. A tensioning device was used to measure the gap and a torque wrench attached to the device was used to apply constant force. RESULTS: Before resection, the average flexion gap was 24.9 mm and the average extension gap was 25.3 mm. After resection, the average flexion gap was 29.8 mm and average extension gap was 27.6 mm. The extension gap was increased 2.2 mm and the flexion gap was increased 4.9 mm which implies that using a thicker polyethylene insert would be favorable after PCL resection. CONCLUSION: After PCL resection, both flexion and extension gaps were increased but the flexion gap was increased more than the extension gap.

Component Size Matched Extension Gap Osteotomy for TKRA: A New Concept in Knee Osteotomy for TKRA / 대한정형외과학회잡지

PURPOSE: We designed a new osteotomy technique in order to get a consistent extension gap along with a tibial polyethelene insert in TKRA. The results were compared to the independent osteotomy technique. MATERIAL AND METHODS: Forty two patients were divided into an independent osteotomy group and a linked osteotomy group according to the technique adopted. In the linked osteotomy group, the extension gap was made by using a linker which was designed to provide a consistent gap between the distal femur and the proximal tibia during knee extension. The widths of the extension gap and the polyethylene thickness was compared between the two groups. RESULTS: The extension gap of the independent osteotomy group was 18.1 +/- 4.2 mm (2SD) and that of the linked femorotibial osteotomy group was 20.3 +/- 1.3 mm (2SD). The polyethylene thickness was 8.1 +/- 2.6 mm (2SD) in the independent group and 9.4 +/- 0.9 mm (2SD) in the linked group. CONCLUSION: This linked femorotibial osteotomy technique provided an improved method for obtaining a tibial insert matched extension gap in TKRA. This technique might also increase the longevity of the polyethylene insert.