A load-measuring device can achieve fine-tuning of mediolateral load at knee arthroplasty but may lead to a more lax knee state

Abstract

Purpose A balanced knee arthroplasty should optimise survivorship and performance. Equilibration of medial and lateral femorotibial load requires guided judicious pericapsular ligament release. The null hypothesis was that there would be no difference between use of a tensiometer device and a remote load sensor final load transfer across the joint through functional arc of motion. Methods A cadaveric study, using eight knees, was performed to define the impact of an established gap distraction device against load sensor-aimed soft tissue release in a TKA setting. Using validated measures of laxity in six degrees of freedom and true real-time load sensing four states were examined: native knee, TKA using spacer blocks (TKA), TKA with soft tissue release aided by a monogram tensiometer (TKA-T) and finally where load across the tibiofemoral articulation remains unbalanced final soft tissue release using a sensor device (TKA-OS). Results The laxity pattern was equivalent for TKA-T and TKA-OS. However, in only four of these seven knees despite the tensiometer confirming equivalence of rectangular flexion–extension gap dimensions and centralisation of collateral ligament distraction, there remained a > 15lb medial to lateral load difference for at least one point of the flexion arc. This was corrected by further final soft tissue release guided by the OS sensor device in the final three knees. Conclusion Tensiometer-guided soft tissue release at two points of flexion failed to achieve balance for three out of seven knee arthroplasty procedures. Sensor technology guided final soft tissue balancing to equilibrate load across the joint through full arc of motion. This work argues for the role of continuous sensor readings to guide the soft tissue balancing during total knee arthroplasty.

Passive ligament stability in natural knee: a cadaveric biomechanical study

“…The results are in agreement to the ones found by other recent experimental (Manning, Blain, Longstaff, & Deehan, 2018) and shown that the tension necessary to stabilize a knee joint in different ligament conditions is way lower than the ones usually applied via tensioners nowadays.…”

Sensor-Assisted Total Knee Arthroplasty: A Narrative Review

“…In a cadaveric study with 7 knees, 26) the tensiometer failed to achieve gap balance for 3 of 7 TKAs; the sensor was able to guide final soft-tissue balancing to equilibrate compartmental loads through the full range of motion. The rectangular flexion and extension gaps may be achieved by modern distraction tensiometers; however, they only measure soft-tissue behavior at 2 points of motion and are very easily influenced by rotational malposition of the femoral and tibial components.…”

“…The rectangular flexion and extension gaps may be achieved by modern distraction tensiometers; however, they only measure soft-tissue behavior at 2 points of motion and are very easily influenced by rotational malposition of the femoral and tibial components. 26 27) In addition, gap equivalence during distraction does not necessarily equate to a balanced load, 9) unless there are equivalent Young's moduli for the medial and lateral soft tissues. 26 28) Sensors can overcome the limitations of the distraction tensiometer in terms of femorotibial incongruence and Young's moduli.…”

Multiple needle puncture combined with repetitive knee manipulation in total knee arthroplasty for correcting varus deformity

“…Ligament balancing in TKA is an important step that effects postoperative function and longevity of prosthesis. 3 Medial release of fixed contracture of medial soft tissue in varus OA knee is necessary to obtain perfect gap balancing. 5 MNP is one technique that has reported to be successful in reaching this goal.…”

“…1,2 Coronal ligament balancing is one of the most important steps that effects outcome and the longevity of implants. 3 In varus osteoarthritis (OA) knee, medial soft tissue is contracted while the lateral soft tissue is elongated. 4 Therefore, medial soft tissue release is performed to correct knee alignment.…”