Robotic Assisted Knee Arthroplasty - Retain the Anterior Cruciate Ligament or Not

The goal of this clinical trial is to compare the function of the knee after retaining or sacrificing the anterior cruciate ligament in robotic assisted knee arthroplasty.

The main questions it aims to answer are:

Does retaining the anterior cruciate ligament improve postoperative gait? Participants will perform

* Gait analysis
* Stair performance test
* CT based Micromotion analysis of the implant micromovement

A randomized controlled clinical trial intended to compare walking function and movement of the prosthesis after robot-assisted knee replacement surgery with two knee replacement designs; One prosthesis is preserving the anterior cruciate ligament (Smith+Nephew Journey II XR) and the other is sacrificing the anterior cruciate ligament (Smith+Nephew Jourrney II CR).

It is common to remove anterior cruciate ligament during knee replacement surgery. There is speculation about this weakens the balance in the operated knee and whether this can explain some of the problems that up to 20% experience after knee replacement surgery.

Preservation of the anterior cruciate ligament during knee replacement surgery may provide a more natural movement and better balance in the operated knee, and this in turn could provide increased patient satisfaction.

Previous studies have shown that knee replacement surgery where the anterior cruciate ligament is preserved has an increased incidence of per- and postoperative complications and reduced implant survival. Robot assisted navigation in knee arthroplasty surgery has shown the possibility of increased precision and accuracy when implanting the knee prostheses, and therefore might provide increased satisfaction when performing elective knee prosthetic surgery with robotic assistance and at the same time preserving the anterior cruciate ligament without an increased risk of complications.

In this study, postoperative function is assessed by looking at whether the walking pattern has normalized.

Gait analyses with comparison of the two groups is carried out both before surgery and 2, 6 and 12 months after surgery.

Primary endpoint is self-selected walking speed at 12 months follow-up. Secondary endpoints include other gait analysis parameters, result of stair test, as well as patient-reported pain, satisfaction and function (NRS, EQ-5D-5L, KOOS-PS, IKSS, FJS-12), knee mobility, stability, and hip-knee-ankle angle.

Complications related to the surgery or the course afterwards is noted. The study will also compare the movement of the prosthetic components in relation to the skeleton over a period of 2 years using a CT based micro motion analysis method (CT-RSA) making it possible to assess implant migration over time.

Increased movement can predict early loosening of the prosthesis.

Eligibility Criteria:
Inclusion Criteria:

* Severe osteoarthritis Ahlbäck grade 3 or 4 affecting 2-3 compartments
* Ability to preoperatively walk 30 m independently without support before surgery
* Ability to give written consent.
* CPAK (Coronal Plane alignment of the Knee) I, II or III

Exclusion Criteria:

* Previous cruciate ligament surgery in affected knee
* Previous osteotomy in affected knee,
* Posttraumatic arthritis in affected knee
* History of infectious arthritis
* Rheumatoid arthritis
* Significant preoperative varus or valgus deformity \>15º
* Evidence of damaged Anterior Cruciate Ligament and/or Posterior Cruciate Ligament
* Flexion contracture \> 10 º, - Planning reveals the need for a complex implant ( stem, augment or higher level of constraint).