Current Concepts in Alignment in Total Knee Arthroplasty

Karasavvidis, Theofilos; Pagan, Cale; Haddad, Fares S.; Hirschmann, Michael T.; Pagnano, Mark W.; Vigdorchik, Jonathan M.

doi:10.1016/j.arth.2023.01.060

Cited by 22 publications

(16 citation statements)

References 53 publications

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“…This approach is not based on outcome data yet, but it allows for deeper insight into normality values of the patients treated. Combining the previously presented functional phenotype concept with the normalised data presented in this study can be used to identify the safe zones as well as target zones for personalised alignment techniques [13–15, 26–28]. If one considers values within mean ± 2SDs as “normal”, mean ± 3 SDs as “deviant” and larger than this as “aberrant”, then the coronal alignment was neutral in 22.7% cases, 63.3% were within normality, 12.1% were deviant, and only 1.8% were aberrant.…”

Section: Discussionmentioning

confidence: 99%

Definition of normal, neutral, deviant and aberrant coronal knee alignment for total knee arthroplasty

Hirschmann,

Khan,

Sava

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeOne of the most pertinent questions in total knee arthroplasty (TKA) is: what could be considered normal coronal alignment? This study aims to define normal, neutral, deviant and aberrant coronal alignment using large data from a computed tomography (CT)‐scan database and previously published phenotypes.MethodsCoronal alignment parameters from 11,191 knee osteoarthritis (OA) patients were measured based on three dimensional reconstructed CT data using a validated planning software. Based on these measurements, patients' coronal alignment was phenotyped according to the functional knee phenotype concept. These phenotypes represent an alignment variation of the overall hip knee ankle angle (HKA), femoral mechanical angle (FMA) and tibial mechanical angle (TMA). Each phenotype is defined by a specific mean and covers a range of ±1.5° from this mean. Coronal alignment is classified as normal, neutral, deviant and aberrant based on distribution frequency. Mean values and distribution among the phenotypes are presented and compared between two populations (OA patients in this study and non‐OA patients from a previously published study).ResultsThe arithmetic HKA (aHKA), combined normalised data of FMA and TMA, showed that 36.0% of knees were neutral within ±1 SD from the mean in both angles, 44.3% had either a TMA or a FMA within ±1–2 SD (normally aligned), 15.3% of the patients were deviant within ±2–3 SD and only 4.4% of them had an aberrant alignment (±3–4 SD in 3.4% and >4 SD in 1.0% of the patients respectively). However, combining the normalised data of HKA, FMA and TMA, 15.4% of patients were neutral in all three angles, 39.7% were at least normal, 27.7% had at least one deviant angle and 17.2% had at least one aberrant angle. For HKA, the males exhibited 1° varus and females were neutral. For FMA, the females exhibited 0.7° more valgus in mean than males and grew 1.8° per category (males grew 2.1° per category). For TMA, the males exhibited 1.3° more varus than females and both grew 2.3° and 2.4° (females) per category. Normal coronal alignment was 179.2° ± 2.8–5.6° (males) and 180.5 > ± 2.8–5.6° (females) for HKA, 93.1 > ± 2.1–4.2° (males) and 93.8 > ± 1.8–3.6° (females) for FMA and 86.7 > ± 2.3–4.6° (males) and 88 > ± 2.4–4.8° (females) for TMA. This means HKA 6.4 varus or 4.8° valgus (males) or 5.1° varus to 6.1° valgus was considered normal. For FMA HKA 1.1 varus or 7.3° valgus (males) or 0.2° valgus to 7.4° valgus was considered normal. For TMA HKA 7.9 varus or 1.3° valgus (males) or 6.8° varus to 2.8° valgus was considered normal. Aberrant coronal alignment started from 179.2° ± 8.4° (males) and 180.5 > ± 8.4° (females) for HKA, 93.1 > ± 6.3° (males) 93.8 > ± 5.4° (females) for FMA and 86.7 > ± 6.9° (males) and 88 > ± 7.2° (females) for TMA. This means HKA > 9.2° varus or 7.6° valgus (males) or 7.9° varus to 8.9° valgus was considered aberrant.ConclusionDefinitions of neutrality, normality, deviance as well as aberrance for coronal alignment in TKA were proposed in this study according to their distribution frequencies. This can be seen as an important first step towards a safe transition from the conventional one‐size‐fits‐all to a more personalised coronal alignment target. There should be further definitions combining bony alignment, joint surfaces' morphology, soft tissue laxities and joint kinematics.Level of EvidenceIII.

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Section: Discussionmentioning

confidence: 99%

Definition of normal, neutral, deviant and aberrant coronal knee alignment for total knee arthroplasty

Hirschmann,

Khan,

Sava

et al. 2024

Knee surg. sports traumatol. arthrosc.

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“…To overcome the described limitations of standardised alignment, various patient‐specific techniques have been popularised in recent years [10], however, until now it is unclear which workflow will provide superior results [11]. As in MA, individualised alignment workflows can be divided into tibia‐first, gap‐balanced techniques and into femur‐first, measured‐resection approaches.…”

Section: Introductionmentioning

confidence: 99%

Tibia‐first, gap‐balanced patient‐specific alignment technique achieves well‐balanced gaps in 90% of cases by rebuilding bony anatomy within boundaries

Strauch,

Kaufmann,

Graichen

2024

Knee surg. sports traumatol. arthrosc.

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PurposePatient‐specific alignment (PSA) technique tries to achieve balanced gaps and simultaneously rebuild the individual bony phenotype. The hypothesis was: PSA technique achieves balanced knees in a high percentage with more anatomical resections than adjusted mechanical alignment (AMA).MethodsThree hundred sixty‐seven patients underwent navigated total knee arthroplasty (TKA) with a tibia‐first gap‐balanced PSA technique. Resection boundaries for medial proximal tibia angle (MPTA) of 86–92°, mechanical lateral distal femoral angle (mLDFA) of 86–92°, and hip‐knee‐ankle angle (HKA) of 175–185° were defined. Preoperative and intraoperative parameters of HKA, MPTA, mLDFA, and gap widths were recorded. Depending on the coronal deformity, the patients were divided into three groups: varus HKA < 178°; straight 178–182° and valgus HKA > 182°. The stability was analysed by assessing the difference between medial and lateral extension and flexion gaps as well as between flexion and extension gaps. All PSA measurements were compared with data from a previously published AMA series.ResultsPSA achieved balanced gaps in extension, flexion and between flexion/extension in over 90% of cases, being similar to AMA. In PSA, MPTA and mLDFA were restored within 1°, except in extreme varus (MPTA difference 2°) and valgus knees (mLDFA difference 3°). This was caused by the defined boundaries of the alignment technique. This individualised reconstruction led to significantly more anatomical resections of all tibia and femur resections.ConclusionA tibia‐first, gap‐balanced PSA technique achieves balanced joints in more than 90% of cases. By maintaining preoperative MPTA and mLDFA to a high extent, far more anatomical resections, compared to AMA were performed. Future studies need to be conducted to investigate whether those promising intraoperative results correlate with postoperative patient outcomes and whether patients outside the 5° corridor have higher failure rates.Level of EvidenceLevel III, retrospective cohort study.

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“…The evolution of navigation and robotics has led surgeons to achieve their target angles consistently and accurately; now, the discussion is around the most effective alignment targets (4). The classification of various phenotypes assists in the proposed starting points for implant position, but soft tissue tension is required in the input data to achieve global balance and stable motion.…”

Section: Discussionmentioning

confidence: 99%

Correction of Coronal Deformity and Intercompartmental Imbalance through Bone Resection

Roche,

Law

2023

J Knee Surg

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Introduction This chapter discusses the correction of coronal deformity and intercompartmental imbalance through bone resection in total knee arthroplasty (TKA). To achieve functional knee balance, coronal, rotational, and sagittal alignment are critical to successful patient outcomes. Though variations in coronal alignment are debated as a correlate to positive results, advancements in utilizing implant position, alignment, and soft tissue balance to improve patient outcomes and function are an evolving discussion. Materials and Methodology The study draws upon existing literature, clinical studies, and surgical techniques related to TKA, including advancements in navigation and robotics. Results The study highlights the importance of individualized alignment strategies for varus and valgus knees. While mechanical neutral alignment has shown excellent long-term data (1), re-evaluating the anatomic recreation of the patient's joint line obliquity is now being studied extensively (2,3). Sensor data and navigation systems contribute to improved outcomes and patient satisfaction. Discussion The evolution of navigation and robotics has led surgeons to achieve their target angles consistently and accurately; now, the discussion is around the most effective alignment targets (4). The classification of various phenotypes assists in the proposed starting points for implant position, but soft tissue tension is required in the input data to achieve global balance and stable motion. Each approach's advantages and limitations are considered. Conclusion In conclusion, achieving optimal coronal alignment, joint line obliquity, and soft tissue balance is crucial for successful TKA outcomes. Personalized alignment philosophies, supported by 3D data and sensor technology, are evolving to minimize critical errors and enhance functional results. Robotic assistance and future advancements in AI and machine learning hold promise for further improving TKA outcomes in the quest for soft tissue stabilization.

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Current Concepts in Alignment in Total Knee Arthroplasty

Cited by 22 publications

References 53 publications

Definition of normal, neutral, deviant and aberrant coronal knee alignment for total knee arthroplasty

Definition of normal, neutral, deviant and aberrant coronal knee alignment for total knee arthroplasty

Tibia‐first, gap‐balanced patient‐specific alignment technique achieves well‐balanced gaps in 90% of cases by rebuilding bony anatomy within boundaries

Correction of Coronal Deformity and Intercompartmental Imbalance through Bone Resection

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