Equal bony resection of distal and posterior femur will lead to flexion/extension gap inequality in robot-assisted cruciate-retaining TKA

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

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Obliteration of Intercondylar Notch Mimicking Flexion-Extension Gap Imbalance in a Cruciate Retaining Total Knee Arthroplasty

Case Reports in Orthopedics ◽

10.1155/2015/716148 ◽

2015 ◽

Vol 2015 ◽

pp. 1-4

Author(s):

Harun Resit Gungor ◽

Esat Kiter ◽

Semih Akkaya ◽

Nusret Ok ◽

Cagdas Yorukoglu

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Postoperative Period ◽

Soft Tissues ◽

Cruciate Ligament ◽

Early Postoperative Period ◽

Intercondylar Notch ◽

Cruciate Retaining ◽

Flexion Extension ◽

Total Knee

Following total knee arthroplasty (TKA), the most frequent cause of extension deficit and limitation of range of motion in early postoperative period is related to improper tensioning of soft tissues and failure to balance extension and flexion gaps. If a cruciate retaining (CR) prosthesis is the planned implant, then attention should be given to balancing the posterior cruciate ligament (PCL), and any factor that alters this balance may also cause deterioration of knee balance in postoperative period. Here, we report on an unusual case referred from another hospital because of continuous pain and restriction of knee motion in early postoperative period following CR-designed TKA that was initially thought to be due to flexion-extension imbalance. However, during the revision procedure, extruded cement to the intercondylar notch was found to be both mechanically blocking terminal extension and limiting flexion by possible mechanism of irritation of the synovial nerve endings around the stretched anterior fibers of PCL during flexion. This case was successfully treated by removal of extruded cement from intercondylar notch to decompress PCL, polyethylene exchange, and secondary patellar resurfacing.

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Flexion—Extension Gap Changes During Total Knee Arthroplasty – Effect of Posterior Cruciate Ligament and Posterior Osteophytes Removal

The Journal of Knee Surgery ◽

10.1055/s-0030-1248201 ◽

2010 ◽

Vol 17 (02) ◽

pp. 69-72 ◽

Cited By ~ 48

Author(s):

A. Baldini ◽

G. Scuderi ◽

P. Aglietti ◽

D. Chalnick ◽

J. Insall

Keyword(s):

Total Knee Arthroplasty ◽

Posterior Cruciate Ligament ◽

Knee Arthroplasty ◽

Cruciate Ligament ◽

Flexion Extension ◽

Total Knee ◽

Extension Gap

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Preoperative factors associated with extension gap in cruciate-retaining total knee arthroplasty: A retrospective study on continuous determination of distraction force

Journal of Orthopaedic Science ◽

10.1016/j.jos.2019.12.004 ◽

2020 ◽

Vol 25 (6) ◽

pp. 1035-1039

Author(s):

Hitoshi Wakama ◽

Yoshinori Okamoto ◽

Shuhei Otsuki ◽

Kosuke Nakagawa ◽

Nobuhiro Okuno ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Retrospective Study ◽

Cruciate Retaining ◽

Factors Associated ◽

Total Knee ◽

Distraction Force ◽

Extension Gap ◽

Preoperative Factors ◽

Continuous Determination

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AssistOn-Finger: An under-actuated finger exoskeleton for robot-assisted tendon therapy

Robotica ◽

10.1017/s0263574714001957 ◽

2014 ◽

Vol 32 (8) ◽

pp. 1363-1382 ◽

Cited By ~ 15

Author(s):

Ismail Hakan Ertas ◽

Elif Hocaoglu ◽

Volkan Patoglu

Keyword(s):

Degrees Of Freedom ◽

Full Range ◽

Feasibility Studies ◽

Dimensional Synthesis ◽

Gap Formation ◽

Robot Assisted ◽

Trade Offs ◽

Flexion Extension ◽

Tendon Tension ◽

Human Finger

SUMMARYWe present AssistOn-Finger, a novel under-actuated active exoskeleton for robot-assisted tendon therapy of human fingers. The primary use for the exoskeleton is to assist flexion/extension motions of a finger within its full range, while decreasing voluntary muscle contractions helping to keep the tendon tension levels to stay within acceptable limits, avoiding gap formation or rupture of the suture. The device can also be employed to administer range of motion (RoM)/strengthening exercises. AssistOn-Fingeris designed to be passively back-driveable, can cover the whole RoM of patients, and can do so in a natural and coordinated manner. In particular, the device employs human finger as an integral part of its kinematics and when coupled to a human operator, the parallel kinematic structure of exoskeleton supports three independent degrees of freedom, dictated by the kinematics of the human finger. Automatically aligning its joint axes to match finger joint axes, AssistOn-Fingercan guarantee ergonomy and comfort throughout the therapy. The self-aligning feature also significantly shortens the setup time required to attach the patient to the exoskeleton. We present the kinematic type selection for the exoskeleton to satisfy the design requirements for tendon therapy applications, detail optimal dimensional synthesis of the device considering trade-offs between multiple design criteria and discuss implementation details of the exoskeleton. We also present feasibility studies conducted on healthy volunteers and provide statistical evidence on the efficacy of exoskeleton driven exercises in keeping the average muscle recruitment and the maximum tendon tension levels as low as human guided therapies.

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

Journal of Clinical Medicine ◽

10.3390/jcm10040845 ◽

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.

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Design of a robot-assisted exoskeleton for passive wrist and forearm rehabilitation

Mechanical Sciences ◽

10.5194/ms-10-107-2019 ◽

2019 ◽

Vol 10 (1) ◽

pp. 107-118

Author(s):

Mehmet Erkan Kütük ◽

Lale Canan Dülger ◽

Memik Taylan Daş

Keyword(s):

Robot Assisted ◽

End Effector ◽

Rehabilitation Process ◽

Flexion Extension ◽

Serial Robot ◽

Articulated Robot ◽

Passive Exoskeleton ◽

Human Limb ◽

Exoskeleton Design ◽

Rehabilitation Exercises

Abstract. This paper presents a new exoskeleton design for wrist and forearm rehabilitation. The contribution of this study is to offer a methodology which shows how to adapt a serial manipulator that reduces the number of actuators used on exoskeleton design for the rehabilitation. The system offered is a combination of end-effector- and exoskeleton-based devices. The passive exoskeleton is attached to the end effector of the manipulator, which provides motion for the purpose of rehabilitation process. The Denso VP 6-Axis Articulated Robot is used to control motion of the exoskeleton during the rehabilitation process. The exoskeleton is designed to be used for both wrist and forearm motions. The desired moving capabilities of the exoskeleton are flexion–extension (FE) and adduction–abduction (AA) motions for the wrist and pronation–supination (PS) motion for the forearm. The anatomical structure of a human limb is taken as a constraint during the design. The joints on the exoskeleton can be locked or unlocked manually in order to restrict or enable the movements. The parts of the exoskeleton include mechanical stoppers to prevent the excessive motion. One passive degree of freedom (DOF) is added in order to prevent misalignment problems between the axes of FE and AA motions. Kinematic feedback of the experiments is performed by using a wireless motion tracker assembled on the exoskeleton. The results proved that motion transmission from robot to exoskeleton is satisfactorily achieved. Instead of different exoskeletons in which each axis is driven and controlled separately, one serial robot with adaptable passive exoskeletons is adequate to facilitate rehabilitation exercises.

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