TY - JOUR
T1 - Robotic-assisted medial unicompartmental knee arthroplasty restores estimated pre-arthritic coronal limb alignment
T2 - A retrospective cohort study
AU - Bayoumi, Tarik
AU - Burger, Joost A.
AU - Zuiderbaan, Hendrik A.
AU - Ruderman, Lindsey V.
AU - Nguyen, Joseph T.
AU - Pearle, Andrew D.
N1 - Publisher Copyright: © 2023 Elsevier B.V.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - Background: Robotic-assisted medial unicompartmental knee arthroplasty (UKA) aims to restore pre-arthritic (constitutional) limb alignment, by re-tensioning of the medial collateral ligament (MCL). This study aimed to determine whether pre-arthritic coronal alignment was restored following robotic-assisted medial UKA in patients with medial compartment osteoarthritis. Method: A retrospective study was undertaken, including 102 patients with a unilateral robotic-assisted medial UKA and a contralateral unaffected knee. Both the validated arithmetic hip-knee-ankle angle (aHKA) and alignment of the contralateral unaffected knee were used to estimate pre-arthritic alignment. The aHKA is a radiographic method to estimate the pre-arthritic mechanical hip-knee-ankle angle (mHKA). To verify restoration of pre-arthritic alignment, postoperative mHKA was compared to the aHKA. Additionally, postoperative mHKA, joint line congruence (JLCA), and knee joint line obliquity (KJLO) angles were compared between the operative and contralateral unaffected knee. Equivalence between postoperative and pre-arthritic alignment was assessed through the two-one-sided t-test (TOST), using equivalence margins of ±2.0°. Results: Postoperative mHKA was equivalent to the aHKA (mean difference −0.38°, 90% CI −0.69 to −0.07; p < .001), with 93 knees (91%) restored within 3.0° their aHKA. Postoperative mHKA, JLCA and KJLO were equivalent between the operative and contralateral unaffected knees, with mean differences of −0.65°, −0.65°, and −0.40°, respectively; all p < .001. Conclusions: Postoperative and pre-arthritic coronal alignment were equivalent following robotic-assisted medial UKA, with 91% of knees restored within 3.0° of their pre-arthritic mechanical axis. These results demonstrate that both mechanical alignment and joint line congruence are restored by MCL re-tensioning in patients undergoing robotic-assisted medial UKA for medial compartment osteoarthritis.
AB - Background: Robotic-assisted medial unicompartmental knee arthroplasty (UKA) aims to restore pre-arthritic (constitutional) limb alignment, by re-tensioning of the medial collateral ligament (MCL). This study aimed to determine whether pre-arthritic coronal alignment was restored following robotic-assisted medial UKA in patients with medial compartment osteoarthritis. Method: A retrospective study was undertaken, including 102 patients with a unilateral robotic-assisted medial UKA and a contralateral unaffected knee. Both the validated arithmetic hip-knee-ankle angle (aHKA) and alignment of the contralateral unaffected knee were used to estimate pre-arthritic alignment. The aHKA is a radiographic method to estimate the pre-arthritic mechanical hip-knee-ankle angle (mHKA). To verify restoration of pre-arthritic alignment, postoperative mHKA was compared to the aHKA. Additionally, postoperative mHKA, joint line congruence (JLCA), and knee joint line obliquity (KJLO) angles were compared between the operative and contralateral unaffected knee. Equivalence between postoperative and pre-arthritic alignment was assessed through the two-one-sided t-test (TOST), using equivalence margins of ±2.0°. Results: Postoperative mHKA was equivalent to the aHKA (mean difference −0.38°, 90% CI −0.69 to −0.07; p < .001), with 93 knees (91%) restored within 3.0° their aHKA. Postoperative mHKA, JLCA and KJLO were equivalent between the operative and contralateral unaffected knees, with mean differences of −0.65°, −0.65°, and −0.40°, respectively; all p < .001. Conclusions: Postoperative and pre-arthritic coronal alignment were equivalent following robotic-assisted medial UKA, with 91% of knees restored within 3.0° of their pre-arthritic mechanical axis. These results demonstrate that both mechanical alignment and joint line congruence are restored by MCL re-tensioning in patients undergoing robotic-assisted medial UKA for medial compartment osteoarthritis.
KW - Knee arthroplasty
KW - Lower limb alignment
KW - Mechanical axis
KW - Pre-arthritic alignment
KW - Robotic-assisted surgery
KW - Unicompartmental knee arthroplasty
UR - http://www.scopus.com/inward/record.url?scp=85146934875&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.knee.2023.01.005
DO - https://doi.org/10.1016/j.knee.2023.01.005
M3 - Article
C2 - 36706493
SN - 0968-0160
VL - 41
SP - 180
EP - 189
JO - KNEE
JF - KNEE
ER -