(iv) Flexion—extension gap theory

2001 ◽  
Vol 15 (6) ◽  
pp. 423-427 ◽  
Author(s):  
D. Macdonald
Keyword(s):  
Flexion Extension ◽  
Extension Gap

Posterior cruciate ligament resection in total knee arthroplasty

2019 ◽  
Vol 101-B (10) ◽  
pp. 1230-1237 ◽  
Author(s):  
Babar Kayani ◽  
Sujith Konan ◽  
Saman Horriat ◽  
Mazin S. Ibrahim ◽  
Fares S. Haddad
Keyword(s):  
Total Knee Arthroplasty ◽  
Posterior Cruciate Ligament ◽  
Knee Arthroplasty ◽  
Cruciate Ligament ◽  
Limb Alignment ◽  
Flexion Gap ◽  
Flexion Extension ◽  
Total Knee ◽  
The Mean ◽  
Extension Gap

Aims The aim of this study was to assess the effect of posterior cruciate ligament (PCL) resection on flexion-extension gaps, mediolateral soft-tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilized (PS) total knee arthroplasty (TKA). Patients and Methods This prospective study included 110 patients with symptomatic osteoarthritis of the knee undergoing primary robot-assisted PS TKA. All operations were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps before and after PCL resection in extension and 90° knee flexion. Measurements were made after excision of the anterior cruciate ligament and prior to bone resection. There were 54 men (49.1%) and 56 women (50.9%) with a mean age of 68 years (sd 6.2) at the time of surgery. The mean preoperative hip-knee-ankle deformity was 4.1° varus (sd 3.4). Results PCL resection increased the mean flexion gap significantly more than the extension gap in the medial (2.4 mm (sd 1.5) vs 1.3 mm (sd 1.0); p < 0.001) and lateral (3.3 mm (sd 1.6) vs 1.2 mm (sd 0.9); p < 0.01) compartments. The mean gap differences after PCL resection created significant mediolateral laxity in flexion (gap difference: 1.1 mm (sd 2.5); p < 0.001) but not in extension (gap difference: 0.1 mm (sd 2.1); p = 0.51). PCL resection significantly improved the mean FFD (6.3° (sd 4.4) preoperatively vs 3.1° (sd 1.5) postoperatively; p < 0.001). There was a strong positive correlation between the preoperative FFD and change in FFD following PCL resection (Pearson’s correlation coefficient = 0.81; p < 0.001). PCL resection did not significantly affect limb alignment (mean change in alignment: 0.2° valgus (sd 1.2); p = 0.60). Conclusion PCL resection creates flexion-extension mismatch by increasing the flexion gap more than the extension gap. The increase in the lateral flexion gap is greater than the increase in the medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity before PCL resection. Cite this article: Bone Joint J 2019;101-B:1230–1237

scholarly journals Flexion-extension gap in cruciate-retaining versus posterior-stabilized total knee arthroplasty: A cadaveric study

2014 ◽  
Vol 32 (5) ◽  
pp. 627-632 ◽  
Author(s):  
Joshua Matthews ◽  
Alexander Chong ◽  
David McQueen ◽  
Justin O'Guinn ◽  
Paul Wooley
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Cadaveric Study ◽  
Posterior Stabilized ◽  
Cruciate Retaining ◽  
Flexion Extension ◽  
Total Knee ◽  
Extension Gap

scholarly journals Medio-Lateral and Flexion-Extension Gap Imbalances in Mechanically Aligned Total Knee Arthroplasty Using Measured Resection Technique in Korean Patients: 3D Simulation

2021 ◽  
Vol 10 (4) ◽  
pp. 845
Author(s):  
Byung Woo Cho ◽  
Ji Hoon Nam ◽  
Yong Gon Koh ◽  
Kwan Kyu Park ◽  
Kyoung Tak Kang
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Valgus Knee ◽  
Varus Knee ◽  
Asian Patients ◽  
Measured Resection ◽  
Flexion Extension ◽  
Total Knee ◽  
Extension Gap ◽  
Flexion And Extension

Background: It is well known that the measured resection (MR) technique in mechanically aligned (MA) total knee arthroplasty (TKA) generates significant gap imbalances, but little is known about whether this applies to the knees of Asian patients. The aim of this study was to evaluate the medio-lateral and flexion-extension gap imbalances and to find the most optimal posterior femoral condyle resection method for operating on the knees of Asian patients. Methods: In total, 738 magnetic resonance imaging (MRI) scans of consecutive patients who underwent TKA were obtained. Four posterior femoral condylar resection methods were used: alignment by the surgical transepicondylar axis (TEA), Whiteside’s line (WSL), 3° external rotation to the posterior condylar axis (PCA), and flexion-extension axis (FEA). Results: For the medial compartments, there were significant differences between the flexion and extension gaps in the varus knee group in all four methods, but there were no differences between the flexion and extension gaps in the valgus knee group. For the lateral compartment, all the methods showed significant differences except for WSL of the valgus knee group and FEA of the varus knee group. Conclusions: In Asian patients, the use of the MA MR technique inevitably leads to medio-lateral or flexion-extension imbalances. Therefore, surgeons should consider which methods can minimize imbalances and choose the best method within the technically possible range.

scholarly journals Intraoperative Assessment of Gap Balancing in Total Knee Arthroplasty Using Navigation with Joint Stability Graphs

2021 ◽  
Author(s):  
Sang Jun Song ◽  
Hyun Woo Lee ◽  
Cheol Hee Park
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Full Range ◽  
Joint Line ◽  
Joint Stability ◽  
Primary Tkas ◽  
Flexion Extension ◽  
Total Knee ◽  
Stability Graph ◽  
Extension Gap

AbstractThe purpose of this study was to assess continuous gaps in the replaced knee throughout the full range of motion (ROM) after total knee arthroplasty (TKA) using a joint stability graph, and to analyze the gap laxity in the mid-flexion range. Ninety-three TKAs were performed using imageless navigation with a joint stability graph. While positioning guides for each respective cut, the surgeon can safely preview the resection's impact for the resulting joint gaps and control the soft tissue balance at the knee flexion of 0° (extension) and 90° (flexion). The gaps between the femoral component and insert were evaluated throughout the full ROM using the joint stability graph. The mechanical axis (MA) and change of joint line height were radiographically evaluated. Posthoc power analyses using a significant α value of 0.05 were performed on the proportion of the mid-flexion instability as a primary outcome to determine whether the sample had sufficient power. The power was determined to be sufficient (100%). The flexion–extension gap differences in each medial and lateral compartment and the mediolateral gap differences in flexion and extension were all ≤3 mm. None of the knees had mid-flexion instability, which is defined by a peak mid-flexion gap that is 3 mm greater than the smaller value of flexion or extension gap. The average MA was well corrected from varus 11.4° to varus 1.0° postoperatively. The proportion of postoperative well-aligned knees (MA ≤ 3°) was 87.1%. The joint line height was well preserved (14.7 vs. 14.8 mm, p = 0.751). The joint stability graph in TKA using the navigation can effectively evaluate the continuous gap throughout the ROM, including the mid-flexion range. Mid-flexion instability was uncommon in primary TKAs with appropriate alignment and proper preservation of the joint line. The Level of evidence for the study is IV.

The effect of anterior cruciate ligament resection on knee biomechanics

2020 ◽  
Vol 102-B (4) ◽  
pp. 442-448
Author(s):  
Babar Kayani ◽  
Sujith Konan ◽  
Syed S Ahmed ◽  
Justin S Chang ◽  
Atif Ayuob ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Cruciate Ligament ◽  
Knee Extension ◽  
Limb Alignment ◽  
Flexion Gap ◽  
Flexion Extension ◽  
Soft Tissue Laxity ◽  
The Mean ◽  
Anterior Cruciate ◽  
Extension Gap

Aims The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA). Methods This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus). Results ACL resection increased the mean extension gap significantly more than the flexion gap in the medial (mean 1.2 mm (SD 1.0) versus mean 0.2 mm (SD 0.7) respectively; p < 0.001) and lateral (mean 1.1 mm (SD 0.9) versus mean 0.2 mm (SD 0.6) respectively; p < 0.001) compartments. The mean gap differences following ACL resection did not create any significant mediolateral soft tissue laxity in extension (gap difference: mean 0.1 mm (SD 2.4); p = 0.89) or flexion (gap difference: mean 0.2 mm (SD 3.1); p = 0.40). ACL resection did not significantly affect maximum knee extension (change in maximum knee extension = mean 0.2° (SD 0.7°); p = 0.23) or fixed flexion deformity (mean 4.2° (SD 3.2°) pre-ACL release versus mean 3.9° (SD 3.7°) post-ACL release; p = 0.61). ACL resection did not significantly affect overall limb alignment (change in alignment = mean 0.2° valgus (SD 1.0° valgus; p = 0.11). Conclusion ACL resection creates flexion-extension mismatch by increasing the extension gap more than the flexion gap. However, gap differences following ACL resection do not create any mediolateral soft tissue laxity in extension or flexion. ACL resection does not affect maximum knee extension or overall limb alignment. Cite this article: Bone Joint J 2020;102-B(4):442–448.

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