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Updated: Apr 10, 2026
In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty
Published on: May 5, 2023
No difference in patella mobility between conventional mechanically aligned and robotic-assisted functionally aligned
Krzysztof Lachowski1, Karim Mustapha Naja1, Robert Prill1,2
1Center of Orthopaedics and Traumatology, University Hospital Brandenburg/Havel, Brandenburg Medical School Theodor Fontane, Brandenburg an der Havel, Germany.
Purpose:
Robotic-assisted (RA) surgery allows for higher accuracy in total knee arthroplasty (TKA) and for better standardization of alignment concepts. It was hypothesized that the more personalized component placement in functional robotic-assisted total knee arthroplasty (RA-TKA) would show an impact on patella mobility and clinical outcome.
Methods:
Prospective study was performed on 80 patients who received TKA (Triathlon; Stryker). In 51 patients, the prosthesis was implanted using MAKO robotic assistance (RA-TKA), while 29 patients underwent conventional implantation (conventional total knee arthroplasty [C-TKA]). Patella mobility was compared pre- and postoperatively after three months. Medial and lateral translation was measured in extension by using a patellostabilometer (PSM), which measures medio-lateral patella mobility under a force of 10 N. Clinical assessment was based on Oxford Knee Score (OKS), Knee Society Score (KSS), Kujala and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores.
Results:
The medio-lateral patella mobility was 31 ± 9 mm before and 34 ± 7 mm (p < 0.01) after surgery. There was no significant difference in mediolateral patella mobility between the two groups (p = 0.282). Patella mobility increased by 3 mm in both groups after surgery. The medial and lateral shift ranged between 14 and 18 mm. All clinical scores (OKS, KSS, Kujala and WOMAC score) improved significantly from before to after surgery (p ≤ 0.001) without difference between the groups.
Conclusions:
RA-TKA did not result in changes in patella mobility when compared to conventional implantation. Other factors, such as general joint laxity or implant design and component placement, may have a more significant impact on patella mobility and clinical outcome.
Level Of Evidence:
Level II, prospective designed study.
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