Geographic Variation in Knee Phenotypes Based on the Coronal Plane Alignment of the Knee Classification: A Systematic Review

Pagan, Cale; Karasavvidis, Theofilos; LeBrun, Drake G.; Jang, Seong Jun; Wood, Jil A.; Vigdorchik, Jonathan M.

doi:10.1016/j.arth.2023.03.047

Cited by 13 publications

(10 citation statements)

References 28 publications

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“…To better evaluate the joint line and to understand how far this might influence the outcome, a lot of research and analysis was done, and the concept of phenotypes was established. This classification confirms a wide variability between individuals and challenges the standard of MA [ 4 , 5 , 6 ].…”

Section: Introductionsupporting

confidence: 69%

Influence of Mechanical Alignment on Functional Knee Phenotypes and Clinical Outcomes in Primary TKA: A 1-Year Prospective Analysis

Rak

Klann

Heinz

et al. 2023

JPM

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In total knee arthroplasty (TKA), functional knee phenotypes are of interest regarding surgical alignment strategies. Functional knee phenotypes were introduced in 2019 and consist of limb, femoral, and tibial phenotypes. The hypothesis of this study was that mechanically aligned (MA) TKA changes preoperative functional phenotypes, which decreases the 1-year Forgotten Joint (FJS) and Oxford Knee Score (OKS) and increases the 1-year WOMAC. All patients included in this study had end-stage osteoarthritis and were treated with a primary MA TKA, which was supervised by four academic knee arthroplasty specialists. To determine the limb, femoral, and tibial phenotype, a long-leg radiograph (LLR) was imaged preoperatively and two to three days after TKA. FJS, OKS, and WOMAC were obtained 1 year after TKA. Patients were categorized using the change in functional limb, femoral, and tibial phenotype measured on LLR, and the scores were compared between the different categories. A complete dataset of preoperative and postoperative scores and radiographic images could be obtained for 59 patients. 42% of these patients had a change of limb phenotype, 41% a change of femoral phenotype, and 24% a change of tibial phenotype of more than ±1 relative to the preoperative phenotype. Patients with more than ±1 change of limb phenotype had significantly lower median FJS (27 points) and OKS (31 points) and higher WOMAC scores (30 points) relative to the 59-, 41-, and 4-point scores of those with a 0 ± 1 change (p < 0.0001 to 0.0048). Patients with a more than ±1 change of femoral phenotype had significantly lower median FJS (28 points) and OKS (32 points) and higher WOMAC scores (24 points) relative to the 69-, 40-, and 8-point scores of those with a 0 ± 1 change (p < 0.0001). A change in tibial phenotype had no effect on the FJS, OKS, and WOMAC scores. Surgeons performing MA TKA could consider limiting coronal alignment corrections of the limb and femoral joint line to within one phenotype to reduce the risk of low patient-reported satisfaction and function at 1-year.

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Section: Introductionsupporting

confidence: 69%

Influence of Mechanical Alignment on Functional Knee Phenotypes and Clinical Outcomes in Primary TKA: A 1-Year Prospective Analysis

Rak

Klann

Heinz

et al. 2023

JPM

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“…Additionally, the unequal sex distribution in their cohort [8], (80% females) may have further contributed to differences compared to the current study. In line with these observations, a recent systematic review reported a wide geographic variation in coronal knee phenotypes of healthy and arthritic knees [20]. These findings further emphasise the importance of considering ethnic differences in understanding knee phenotypic variation at the population level.…”

Section: Discussionsupporting

confidence: 58%

The phenotypic diversity of anteromedial osteoarthritis before and after treatment with medial unicompartmental knee arthroplasty: A radiographic analysis of 1000 knees

Bayoumi,

ten Noever de Brauw,

Ruderman

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeThis study aimed to assess phenotypic variation in the coronal plane of knees with anteromedial osteoarthritis using the functional knee phenotype classification, before and after treatment with medial unicompartmental knee arthroplasty (UKA).MethodsThe study comprised 1000 knees of 835 patients (45% females, 55% males, 90% Caucasian) who underwent medial UKA for anteromedial osteoarthritis. Pre and postoperative alignment was evaluated through the hip‐knee‐ankle angle (HKA), femoral mechanical angle (FMA), and tibial mechanical angle (TMA). Knees were classified according to the functional knee phenotype system which combines limb phenotype (HKA), and femoral and tibial knee phenotypes (FMA and TMA, respectively). Restoration of prearthritic coronal alignment following medial UKA was evaluated by phenotype.ResultsPreoperatively, 76 distinct and 25 relevant (prevalence ≥1%) functional knee phenotypes were identified, of which VARHKA6°VARFMA3°NEUTMA0° was the most common (9.4% of knees). The most prevalent limb phenotype, VARHKA6°, comprised 15 distinct knee phenotypes (FMA and TMA combinations). Postoperatively, 58 distinct and 17 relevant functional knee phenotypes were observed, of which VARHKA3°NEUFMA0°NEUTMA0° had the highest prevalence at 18.3%. Knees with combined tibial and femoral deformities were associated with a lower probability of restoration of prearthritic coronal alignment following medial UKA, compared to knees without extra‐articular deformity, or knees with an isolated tibial or femoral deformity.ConclusionPhenotype analysis using the functional knee phenotype system demonstrated a wide diversity of coronal alignment phenotypes among knees with anteromedial osteoarthritis in a predominantly Caucasian population. Following medial UKA, a reduction from 25 preoperative to 17 postoperative relevant phenotypes was observed. Consideration of phenotypic variation can be of importance when aiming to restore prearthritic coronal alignment during medial UKA.Level of EvidenceLevel III, retrospective cohort study.

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“…Another important finding of this study is that caliper-verified unKATKA successfully restored the patient's constitutional alignment concerning the CPAK classification. Geographic variations in CPAK have been well-reviewed in a previous study [25]. A higher prevalence of varus knee phenotypes (type I and type IV) and a lower prevalence of type V phenotypes in patients with OA have been reported in Asian TA B L E 4 Analysis of implant survival for the categories of postoperative alignment of varus outlier range, valgus outlier range and in-range.…”

Section: Discussionmentioning

confidence: 94%

Caliper‐verified unrestricted kinematically aligned total knee arthroplasty in Asian patients showed efficacious mid‐ to long‐term results regardless of postoperative alignment categories

Won,

Eim,

Shen

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeThere have been insufficient data regarding the long‐term results of unrestricted kinematically aligned total knee arthroplasty (unKATKA) in Asian patients. We investigated mid‐ to long‐term clinical and radiological follow‐up data of Korean patients after caliper‐verified unKATKA of minimum 7.4–10 years including categorised data of postoperative tibial component, limb and knee alignment. Additionally, we analysed the preoperative distribution and postoperative restoration of coronal plane alignment of knee (CPAK) phenotypes.MethodsThis study is a retrospective analysis of 63 patients: 96 osteoarthritic underwent consecutive caliper‐verified unKATKA between October 2013 and May 2016 by a single surgeon. Implant survivorship was investigated for revision for any reason. Each knee was categorised into an in‐range or outlier group by three postoperative alignment parameters: tibial component, knee and limb alignment. Statistical analyses were done for any significant differences in clinical scores and implant survival rates between groups. Finally, all knees were classified into CPAK classification postoperatively and postoperatively. The CPAK restoration rate was calculated.ResultsAmong 85 knees in the clinically confirmed group, implant survival was 98.8%. There was one case of revision due to periprosthetic fracture. The percentage postoperatively aligned in the varus (valgus) outlier range was 100% (0%) for tibial component, 16.7% (24.8%) for the knee alignment and 51% (0%) for the limb alignment. All three categories did not affect implant survival or clinical scores. Eighty one out of 96 knees (84.4%) were restored to their CPAK phenotype postoperatively.ConclusionWith the limitation of a case series having a small number of patients and gender deviation, our study suggests that caliper‐verified unKATKA could be a good option regardless of geographical variation of constitutional alignment in patients with osteoarthritis (OA).Level of EvidenceLevel IV, therapeutic study.

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Geographic Variation in Knee Phenotypes Based on the Coronal Plane Alignment of the Knee Classification: A Systematic Review

Cited by 13 publications

References 28 publications

Influence of Mechanical Alignment on Functional Knee Phenotypes and Clinical Outcomes in Primary TKA: A 1-Year Prospective Analysis

Influence of Mechanical Alignment on Functional Knee Phenotypes and Clinical Outcomes in Primary TKA: A 1-Year Prospective Analysis

The phenotypic diversity of anteromedial osteoarthritis before and after treatment with medial unicompartmental knee arthroplasty: A radiographic analysis of 1000 knees

Caliper‐verified unrestricted kinematically aligned total knee arthroplasty in Asian patients showed efficacious mid‐ to long‐term results regardless of postoperative alignment categories

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