Knee Moments After Unicompartmental Knee Arthroplasty During Stair Ascent

Abstract

Background For unicompartmental knee arthroplasty (UKA), abnormal loading on the tibiofemoral joint could exacerbate knee osteoarthritis or implant wear. Joint moments are an indirect measure of such loading. However, little is known about knee moments of patients with UKA, tempering enthusiasm for its use. Questions/purposes In patients with UKAs performing stair ascent, we (1) determined whether interlimb differences for knee moments are demonstrated, (2) described the knee kinetics of patients with medial and lateral UKAs, and (3) investigated possible factors that might influence the knee abductor moments. Methods In our cross-sectional study, we recruited 26 patients with UKA with nondiseased contralateral limbs who performed stair ascent. Seventeen patients had medial UKAs and nine had lateral UKAs. Paired t-tests and CIs were applied to determine interlimb differences within each UKA group for peak knee moments and times to peak moments. Results During stair ascent, the medial UKA group displayed greater peak extensor moments for the nondiseased compared to the UKA limb (p = 0.030), whereas the lateral UKA group did not (p = 0.087). For both medial and lateral UKA groups, the UKA limb demonstrated greater internal peak abductor moments (p = 0.005 and 0.013, respectively). Both UKA groups exhibited knee moments similar to those in the literature. Limb dominance and postoperative time were correlated for both UKA groups. Conclusions Reduced knee extensor moments of limbs with UKA displayed by some participants may indicate less compressive loading on the tibiofemoral joint surfaces,

A Morphometric Fixed-Bearing Unicompartmental Knee Arthroplasty Can Reproduce Normal Knee Kinematics. An In Vitro Robotic Evaluation

“…The main described difference concerned the varus-valgus movement [ 23 , 24 ]. The varus rotation in flexion was decreased significantly [ 25 , 26 ], with the loss of lateral laxity in flexion [ 23 ]. With a morphometric implant, we found restoration of the preoperative varus-valgus movement over the full range of motion, with preservation of the physiological lateral laxity in flexion.…”

“…In cadaver studies, the knee motion after UKA has been described close to normal [ 8 , 10 ], but when performed in vivo, the results were sometimes less obvious [ [22] , [25] , [26] , [27] ]. An in vitro assessment with more complex movements is thus interesting.…”

“…In vivo, simple daily activities, such as squatting motion or stair ascent, were assessed by fluoroscopy or gait analysis after UKA. The knee kinematics in vivo after fixed-bearing or mobile-bearing UKA was not completely restored during squatting [ 13 , 23 ] or stair ascent [ 25 ]. Moreover, the patients with medial UKA displayed a reduced range of knee flexion compared with the healthy population during daily activities [ 25 , 26 ].…”

“…The knee kinematics in vivo after fixed-bearing or mobile-bearing UKA was not completely restored during squatting [ 13 , 23 ] or stair ascent [ 25 ]. Moreover, the patients with medial UKA displayed a reduced range of knee flexion compared with the healthy population during daily activities [ 25 , 26 ]. These are muscularly demanding daily functional activities and, therefore, an excellent functional evaluation of UKA.…”

Evaluation of Knee Kinematics and Moments during Active Deep Flexion Activity after Oxford Mobile-Bearing Medial UKA—A Two-Year Follow-Up Study

“…Another study 27 showed that although some abnormalities persisted in muscle activity around the knee, a good restoration of gait was achieved by most unicompartmental knee patients independently of the UKA design. Multiple UKA gait scene such as stair ascent, 28 downhill walking, 29 and on a level and sloped grounds 30 have been studied to demonstrate the biomechanical characteristics of UKA.…”