Anatomical reconstruction? Yes, just please!

Joint line

Anatomical reconstruction? Yes, just please!

Join line

Course report 4-motion® workshop, July 3, 2021

Anatomical reconstruction? Yes, just please!

Is it still up to date to mechanically align all knees to 90°/90° degrees? “No” is the answer of the “4-motion® Workshop: Better Outcomes with Kinematic Alignment”, which was held in Essen for the first time on July 3, 2021 thanks to the low number of Covid-19 infections. Under the scientific direction of Prof. Dr. Henrik Schroeder-Boersch, Wiesbaden, the participants discussed the complexity of the knee anatomy and various alignment strategies before they got to know the 4-motion® knee system practically on the specimen under the guidance of expert instructors. The conclusion of the participants: Finally there is a simple and well thought-out implementation for the anatomical reconstruction.

For years, the literature has confirmed that between 15% and 25% of patients are dissatisfied after TKA, Schroeder-Boersch referred to the study situation. “The question has clinical relevance. In the past 5 to 10 years, the specialist community has been increasingly discussing the move away from the 90°/90° alignment of the knee towards a kinematic-anatomical alignment,” explained Schroeder-Boersch.

Restoring the natural joint line is the central element for anatomical reconstruction. “We should realize that we want to go back to where the cartilage surface used to be,” summarized Schroeder-Boersch.

Two thirds of patients have an 87°/87° joint line

Preoperative anatomical CT data from 143 patients, which the company ARTIQO evaluated in the course of developing the 4-motion® knee prosthesis, confirm the frequency of a medially inclined articulation plane. About two thirds of the patients (n=92) showed a varicose joint plane between 80.5 and 87.9 degrees. A smaller group (n=25) still had a slightly inclined plane between 88 and 89.5 degrees, while the last sixth (n=26) had a neutral or slightly valgus joint plane between 89.6 and 93.2 degrees.

“The reconstruction of the joint line also means that we achieve the movement around the correct axis when flexing the knee joint,” emphasized Schroeder-Boersch. In addition to the correct joint line, the evenness of the flexion and extension gaps and the ligament stability in the various flexed positions are important prerequisites for a good clinical result, a stable joint and good function. If this does not succeed, the distances between the inner and outer ligaments to the joint surface change and with it the stabilizing function of the ligament structures. “Then the knee no longer works as it should, although we leave the ligaments alone,” stated Schroeder-Boersch.

A recently published meta-analysis certifies that kinematic alignment better results than the mechanical approach. Eleven randomized controlled trials that met the inclusion criteria and included 1,103 patients were included in the analysis. Alignment was kinematic in 553 patients and mechanical in 550 patients. The follow-up period was mostly between 6-24 months. The WOMAC score (599 patients) was significantly better in the kinematic group with 10 points (p<0.001), as was the combined Knee Society Score (KSS) with 18 points (p<0.001). The KOOS score, which measures symptoms, pain, activities of daily living, exercise, and quality of life (291 patients), was not significantly different between the two groups, while flexion (ROM) was slightly better in the kinematic group at 5 degrees than in the comparison group. In addition, there was significantly less ligament release in the kinematic than in the mechanical group.

“These are very good clinical results that we cannot ignore,” emphasized Schroeder-Boersch. However, this requires a prosthesis system that was designed for an anatomical reconstruction and that can reproduce the variability of the human knee.

Simplicity and anatomical reconstruction are not mutually exclusive

That’s why Schroeder-Boersch has been working with the 4-motion® knee system for three quarters of a year: “Anyone who knows Ulli Bücken knows that anatomical alignment has been a matter close to his heart for years.” This is not an exclusive idea from ARTIQO, but only the discussion the endoprosthetic community in recent years, which has increasingly doubted mechanical alignment. With the 4-motion® knee system there is now a system that allows this procedure.

The 4-motion® knee system approaches this topic from three directions: It has three-dimensional preoperative planning, patient-specific cutting blocks and implant components that are designed and approved for individual anatomical alignment.

“The preoperative planning and the algorithm follow the current state of the literature,” explained Mario Frank, member of the management and developer of ARTIQO GmbH. “The 3D planning shows the surgeon transparently how the components are positioned based on the state-of-the-art planning.” In order to meet the precise planning specifications, patient-specific cutting blocks are manufactured. In addition, the 4-motion® prosthesis system was designed and approved for the anatomical reconstruction of the joint line. “Right from the start of development, we wanted to be able to reconstruct the anatomical variability of the joint line,” explained Frank.

The course participants were also able to convince themselves of this in a very practical way by looking at the various preparations. The preparations were anatomically reconstructed according to the specifications using the three-dimensional planning that had been created in advance with the planning algorithm, the PSI cutting blocks and the implant components. The conclusion: finally there is a simple and well thought-out implementation for anatomical reconstruction.


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Impressions from the 4-motion® workshop on July 3, 2021 in the TripleZ in Essen