Systematic alignments yield balanced knees without additional releases in only 11% of knee arthroplasties: a prospective study

Abstract

PurposeThe literature suggests that "forgotten" knees are the most stable knees postoperatively. The main objective of our study was to determine whether a systematic alignment (mechanical, anatomical or kinematic) makes it possible to stabilise the operated joint in extension and in lexion. Methods This monocentric prospective cohort study was conducted between May 1st, 2021 and October 31st, 2021. A total of 132 consecutive patients undergoing primary navigated total knee arthroplasty were included, with a mean age of 72.4 years (7.9; 48.8-91.2 years), a mean body mass index (BMI) of 28.6 kg/m 2 (4.6; 17.6-41.6) and 71.2% (94/132) women. Mechanical, anatomical and kinematic knee alignments were simulated using Kick software for each patient. The primary outcome was the targeted rate of balanced knees for each type of alignment, based on a three-point score, aiming for a 3/3 score for each knee. Our secondary outcome was to characterise the speciic implantation inally achieved by the surgeon. ResultsThe targeted balance was reached in 10.6% (14/132), 10.6% (14/132) and 12.9% (17/132) of knees with mechanical, anatomical and kinematic alignment simulations, respectively. None of these simulations provided a superior number of balanced knees (p = 0.87). When simulating a patient-speciic implantation, the highest score was reached in 89.1% (115/132) of cases. Conclusion Systematic alignment simulations achieved knee balance in only 11% of cases. Patient-speciic implantation, favouring knee balancing over alignment, allowed an 89% perfect score rate without having to perform any collateral release. Level of evidence Case series. Level 4.

Alignment is only part of the equation: High variability in soft tissue distractibility in the varus knee undergoing primary TKA

“…Together, this study adds to knowledge on joint distractibility across a range of deformities and further suggests that targeting alignment alone may lead to poor soft tissue tensioning in TKA [3,10,15,24]. The population trend for increased medial distractibility with increased varus deformity may be unexpected.…”

“…With the increasing utilization of kinematic alignment‐based TKA, an enhanced understanding of native soft tissue tensions may help direct surgical technique and kinematic goals. Together, this study adds to knowledge on joint distractibility across a range of deformities and further suggests that targeting alignment alone may lead to poor soft tissue tensioning in TKA [3, 10, 15, 24].…”

“…In contrast, a moderate varus deformity with native varus femur has a lower chance of correctability to a neutral mechanical axis. In addition, the high variability within each deformity category suggests that an individualized approach to kinematic techniques may be more appropriate when combined with accurate joint tensioning technology and that targeting alignment alone may lead to significant variability in medial gapping [3,7,10,15,16,24].…”

Automatic measurement of lower limb alignment in portable devices based on deep learning for knee osteoarthritis

“…The HRNet model, proposed for visual recognition problems in 2D images, was adopted in our study [23]. Compared to existing low-resolution classification networks or high-resolution representational learning networks, HRNet was characterised by the following features: it connected high-and low-resolution convolutions in parallel; it maintained high resolution throughout the process, rather than recovering high resolution from low resolution; it repeatedly fused multiresolution representations, producing rich high-resolution representations with strong positional sensitivity; its storage cost was comparable to available technologies [4]. These features allowed us to guarantee accurate measurements while allowing the model to run on portable devices.…”

“…Lower limb alignment is a critical aspect that surgeons carefully evaluate when assessing deformity, predicting treatment outcomes, and planning for surgery. For cases involving knee OA, the majority of surgeons agree that achieving a neutrally aligned lower limb after TKA is a crucial objective [ 4 ].…”