Restricted Inverse Kinematic Alignment Better Restores the Native Joint Line Orientation While Achieving Similar Balance, Laxity, and Arithmetic Hip-Knee-Ankle Angle to Gap Balancing Total Knee Arthroplasty

Self Cite

PurposeThe relationship between constitutional coronal alignment and implant positioning on trochlear groove restoration in total knee arthroplasty (TKA) is poorly understood. This study aimed to determine whether the choice of alignment philosophy significantly affects the restoration of the trochlea groove.MethodsSixty‐one imageless robotic TKAs performed by a single orthopaedic surgeon were retrospectively reviewed. In each case, the entire native trochlea was digitized to generate the native femoral anatomy, and implants were planned according to a functional alignment (FA) technique. Final implant position was recorded using the validated bone resection planes from the navigation system. Simulated femoral component positions were generated according to previously described alignment techniques: mechanical alignment (MA), gap balancing (GB), kinematic alignment (KA), restricted kinematic alignment (rKA) and restricted inverse kinematic alignment (riKA). Trochlear angle (TA), trochlear under/overstuffing and mediolateral sulcus offset were compared between the six simulated alignment techniques, as well as the final implanted technique. Further analyses investigated the effect of preoperative coronal alignment on trochlear position. Comparisons were assessed with an analysis of variance and Welch's t‐tests or Wilcoxon's rank‐sum tests with Bonferroni corrections.ResultsThe implanted and simulated techniques all resulted in greater TA valgus compared to the native groove (p < 0.001). The implanted technique, KA and rKA were closer to the native TA than GB, MA and riKA (p > 0.001). All alignment philosophies understuffed the native trochlea groove. KA and rKA understuffed less than all other techniques (p < 0.001), and GB understuffed more than all other techniques (p < 0.001). In extension, all techniques shifted the trochlear sulcus laterally, while in flexion, they medialized it. These effects were most prominent in GB and MA.ConclusionPersonalized alignment techniques such as KA and rKA, which consider variations in individual anatomy, best restore the native patellar groove compared to systematic alignment techniques when using a standardized femoral component.Level of EvidenceLevel III, retrospective review.

Section: Methodsmentioning

confidence: 99%

Personalized alignment techniques better restore the native trochlear groove compared to systematic alignment techniques in total knee arthroplasty

Orsi,

Shatrov,

Plaskos

et al. 2024

Self Cite

“…All robotic data were then imported in R to simulate resections according to a functional alignment technique with tibia-first balancing under different boundary conditions for the tibial resection [22,35]. An anatomic tibial resection was virtually performed first, by aligning the tibial resection to the native MPTA, after correcting for bone and cartilage wear as described further below.…”

Section: Tibial Boundaries and Femoral Component Alignment Simulationsmentioning

confidence: 99%

Widening of tibial resection boundaries increases the rate of femoral component valgus and internal rotation in functionally aligned TKA

Ollivier,

Wakelin,

Plaskos

et al. 2024

Self Cite

PurposeThe purpose of this study was to investigate the influence of increasing the tibial boundaries in functional alignment on femoral component orientation in total knee arthroplasty (TKA).MethodsA retrospective review of a database of robotic‐assisted TKAs using a digital joint tensioning device was performed (BalanceBot®; Corin). A total of 692 TKAs with correctable deformity were included. Functional alignment with a tibia‐first balancing technique was simulated by performing an anatomic tibial resection to recreate the native medial proximal tibial angle within certain boundaries (A, 87–90°; B, 86–90°; C, 84–92°), while accounting for wear. After balancing the knee, the resulting amount of femoral component outliers in the coronal and axial plane was calculated for each group and correlated to the coronal plane alignment of the knee (CPAK) classification.ResultsThe proportion of knees with high femoral component varus (>96°) or valgus (<87°) alignment increased from 24.5% (n = 170) in group A to 26.5% (n = 183) in group B and 34.2% (n = 237) in group C (p < 0.05). Similarly, more knees with high femoral component external rotation (>6°) or internal rotation (>3°) were identified in group C (33.4%, n = 231) than in group B (23.7%, n = 164) and A (18.4%, n = 127) (p < 0.05). There was a statistically significant (p < 0.01) overall increase in knees with both femoral component valgus <87° and internal rotation >3° from group A (4.0%, n = 28) to B (7.7%, n = 53) and C (15.8%, n = 109), with CPAK type I and II showing a 12.9‐ and 2.9‐fold increase, respectively.ConclusionExtending the tibial boundaries when using functional alignment with a tibia‐first balancing technique in TKA leads to a statistically significant higher percentage of knees with a valgus lateral distal femoral angle < 87° and >3° internal rotation of the femoral component, especially in CPAK type I and II.Level of EvidenceLevel IV.

“…For varus knees, the numbers were lower (>50% and 66%-80%), and for valgus knees, the lowest (between 5% and 20%). Orsi et al described for the entire group of knees a CPAK restoration with their inverse KA (iKA) technique of only 32% [23]. The reason for this difference can be the surgical technique itself.…”

Section: Preoperativementioning

confidence: 99%

Tibia‐first, gap‐balanced patient‐specific alignment restores bony phenotypes and joint line obliquity in a great majority of varus and straight knees and normalises valgus and severe varus deformities

Graichen,

Avram,

Strauch

et al. 2024

PurposeThe present study focuses on testing the capability of a restricted tibia‐first, gap‐balanced patient‐specific alignment technique (PSA) to restore bony morphology and phenotypes.MethodsThree‐hundred and sixty‐seven patients were treated with navigated total knee arthroplasty and tibia‐first gap‐balanced PSA technique. Boundaries for medial proximal tibial angle were 86°–92°, mechanical lateral distal femoral angle 86°–92°, and hip–knee–ankle angle 175°–183°. Knees were classified by coronal plane alignment of the knee (CPAK), with subsequent analyses comparing pre‐ and postoperative distributions. Phenotype classification within CPAK groups assessed pre‐ and postoperative distributions.ResultsPreoperatively, the largest CPAK group was type II (30.8%), followed by type I (20.5%) and type V (17.8%). Postoperatively, type II remained the largest group (39%), followed by type V (30%). All groups with varus/valgus deformities (I, III, IV and VI) became smaller. While in straight legs (II, IV), the CPAK was restored in more than 70%–75%, in varus groups (I, IV) in 40%–50% and in valgus (III and VI) in 5%–18%. The joint line obliquity remained the same in the majority of knees (straight >75%; varus 63%–80%; valgus VI 95%), with the exception of CPAK III (40%). The phenotype analysis showed for straight legs a phenotype restoration of 85%, for varus 94% and for valgus 37%. Joint line convergence angle was reduced significantly in all groups from 1.8°–4.3° preoperatively to 0.6°–1.2° postoperatively.ConclusionPSA restores bony phenotypes and joint line obliquity in the majority of straight and varus knees, while most of the valgus and extreme varus knees are normalised.Level of EvidenceLevel III, retrospective cohort study.