Functionally aligned total knee arthroplasty: A lateral flexion laxity up to 6 mm is safe!

Nixon, Jeremy; Tadros, Baha John; Moreno‐Suarez, Ignacio; Pretty, William; Collopy, Dermot; Clark, Gavin

doi:10.1002/ksa.12087

Cited by 3 publications

(5 citation statements)

References 27 publications

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“…Anatomically, the knee presents more contact in the medial compartment than in the lateral, suggesting that the centre of rotation of the knee is in the medial compartment [ 28 , 29 , 30 , 32 ]. Consequently, more significant laxity in the lateral compartment [ 9 , 13 , 34 ] would enable the physiologic posterolateral femoral roll-back [ 13 , 21 ]. Thus, it seems reasonable that some authors [ 13 , 21 , 33 ] observed better outcomes when a certain degree of asymmetry was present.…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, more significant laxity in the lateral compartment [ 9 , 13 , 34 ] would enable the physiologic posterolateral femoral roll-back [ 13 , 21 ]. Thus, it seems reasonable that some authors [ 13 , 21 , 33 ] observed better outcomes when a certain degree of asymmetry was present.…”

Section: Discussionmentioning

confidence: 99%

“…Achieving perfect soft-tissue balance during TKA is difficult, so a 0 to 2 mm difference between the medial and lateral compartments is still considered symmetrical [ 11 , 15 , 21 ]. It is plausible that when restoring constitutionality, there will be inequalities in the joint gaps through the medial and lateral compartments, with a more significant lateral gap than the medial during flexion.…”

Section: Discussionmentioning

confidence: 99%

“…It is plausible that when restoring constitutionality, there will be inequalities in the joint gaps through the medial and lateral compartments, with a more significant lateral gap than the medial during flexion. Therefore, some authors have postulated that a slight asymmetry in the gap balance may be acceptable [ 10 , 11 , 13 , 17 , 21 ]. Our findings support this statement, with no significant differences between the symmetric (0–2 mm) and asymmetric (2–5 mm) flexion gaps in knee function and clinical scores.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, computer- and robotic-assisted technologies enable the control of the three-dimensional component position and help to objectify the femorotibial gaps [ 9 ]. However, in this context, new alignment philosophies, such as inverse kinematic alignment or functional alignment, are still based on the principle of equal and symmetric flexion and extension gaps [ 19 , 20 , 21 ]. This contrasts with the kinematic alignment (KA) idea, which aims to align the knee prosthesis components to closely restore the patient’s constitutional and prearthritic anatomy and thus achieve more natural soft tissue tension and kinematics of the patient’s knee [ 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

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Maintaining the Physiological Lateral Flexion Gap in the Kinematically Aligned TKA Does Not Compromise Clinical Outcomes at One-Year Follow-Up

Jimenez-Soto,

Moya-Angeler,

León-Muñoz

et al. 2024

JCM

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Background: Instability is a common cause of (total knee arthroplasty) TKA failure, which can be prevented by achieving proper gap balance during surgery. There is no consensus on the ideal gap balance in TKA, and different alignment philosophies result in varying soft-tissue tightness. Traditional TKA aims for symmetric compartment balance, while kinematic alignment (KA) restores anatomy and accepts asymmetric flexion gaps. This study evaluated the impact of these philosophies on the flexion gap balance and clinical outcomes. Methods: A retrospective review of 167 patients who received true or restricted KA robotic-assisted TKA with at least one year of follow-up was conducted. The groups were based on intraoperative flexion gap differences: symmetric (0–1 mm) (n = 94) and asymmetric (2–5 mm) (n = 73). Results: Preoperative demographics and postoperative clinical and functional scores were compared. Both groups were similar in demographics and preoperative scores. True KA alignment was more likely to result in an asymmetric flexion gap, while restricted KA produced symmetric gaps. Conclusions: The study found no adverse effects from the physiological asymmetric flexion gap, with clinical and functional outcomes comparable to symmetric gaps. A 5 mm difference between the medial and lateral gap width did not negatively impact the outcomes. True KA more frequently results in a physiological asymmetric flexion gap.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Maintaining the Physiological Lateral Flexion Gap in the Kinematically Aligned TKA Does Not Compromise Clinical Outcomes at One-Year Follow-Up

Jimenez-Soto,

Moya-Angeler,

León-Muñoz

et al. 2024

JCM

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Intraoperative lateral laxity greater than 4° is associated with inferior functional improvement in posterior‐stabilised total knee arthroplasty

Inokuchi,

Muratsu,

Kamenaga

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeThe study aimed to determine the impact of intraoperative lateral laxity at extension on clinical and functional outcomes 1 year after posterior‐stabilised total knee arthroplasty (PS‐TKA).MethodsIn total, 91 varus‐type osteoarthritic knees that underwent PS‐TKA using the medial preservation gap technique were included. After the femoral trial component placement and patellofemoral joint reduction, the soft‐tissue balance was assessed using an offset‐type tensor with a 40‐lb joint‐distraction force. Patients were divided into the following three groups according to the intraoperative lateral laxity at extension (i.e., varus ligament balance) using the mean ± 1 standard deviation: Groups A, ≤0°; B, 0–4°; and C, >4°. The 2011 Knee Society Score (KSS) and 3‐m timed up‐and‐go test (TUG) time 1‐year postoperatively, and their improvements were compared among the groups.ResultsWhile significant improvements were observed in all subscales of the 2011 KSS and TUG post‐TKA (p < 0.05), the improvement of functional activities and TUG time were significantly lower in Group C than in Group B (p < 0.05). However, no significant differences were observed in symptom improvement, patient satisfaction or patient expectation scores among the groups.ConclusionAn excessive lateral laxity (varus angle) >4° at extension was associated with lower improvement in functional ability 1‐year postoperatively. Therefore, excessive intraoperative lateral laxity should be avoided in PS‐TKA.Level of EvidenceLevel IV.

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Impact of Joint Laxity on 2-Year KOOS Outcomes of Posterior Stabilized Total Knee Arthroplasty

Randall,

Wakelin,

Kah

et al. 2024

J Knee Surg

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Background: The objective of this study was to determine relationships between intra-operative posterior cruciate ligament (PCL) sacrificing posterior stabilized (PS) total knee arthroplasty (TKA) laxity measurements throughout flexion and patient outcomes at 2-years post-TKA; and to define clinically relevant laxity thresholds to optimize patient outcomes. Methods: In a single surgeon study, PCL sacrificing TKA using a robotics assisted platform with a digital joint tensioning device was performed in 115 knees in 115 patients. Final intra-operative joint laxity was recorded, and 2-year Knee Injury and Osteoarthritis Outcome Scores (KOOS) were obtained. A Simulated Annealing optimisation algorithm was used to identify medial and lateral laxity windows which maximized the 2-year KOOS pain score. Wilcox non-parametric tests were used to compare outcomes between groups. Results: Significant associations were found between intra-operative joint laxity and 2-year KOOS pain outcomes throughout flexion. Clinically relevant laxity windows were defined medially and laterally in mid-flexion and flexion for improved outcomes, whereas only a lateral laxity window could be defined in extension. When all laxity windows were satisfied a 14.5 KOOS point improvement was found (97.2 vs 77.8, p=0.0060) compared to knees which did not satisfy any window. Improvements in Activities of Daily Living (∆8.8, p = 0.0143), Sports (∆22.5, p = 0.0108), and Quality of Life (∆18.7, p = 0.0011) KOOS subscores were also found in knees which satisfied all windows versus 0 – 1 window. Conclusion: Intra-operative joint laxity is associated with post-operative outcomes in a PS knee design, wherein patients balanced within identified laxity targets reported improved outcomes over those that did not. Clinically significant thresholds were defined and were predominately found in mid-flexion and flexion for medial and lateral laxity. When target windows were combined further improved outcomes were identified.

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Functionally aligned total knee arthroplasty: A lateral flexion laxity up to 6 mm is safe!

Cited by 3 publications

References 27 publications

Maintaining the Physiological Lateral Flexion Gap in the Kinematically Aligned TKA Does Not Compromise Clinical Outcomes at One-Year Follow-Up

Maintaining the Physiological Lateral Flexion Gap in the Kinematically Aligned TKA Does Not Compromise Clinical Outcomes at One-Year Follow-Up

Intraoperative lateral laxity greater than 4° is associated with inferior functional improvement in posterior‐stabilised total knee arthroplasty

Impact of Joint Laxity on 2-Year KOOS Outcomes of Posterior Stabilized Total Knee Arthroplasty

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