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Effect of polyethylene conformity on total knee arthroplasty early clinical outcomes.
Knee Surg Sports Traumatol Arthrosc. 2019 Apr; 27(4):1028-1034.KS

Abstract

PURPOSE

Total knee arthroplasty is a successful procedure in treating subjects with end-stage knee osteoarthritis. The objective of this matched study was to evaluate subjective patient satisfaction and clinical and radiological outcomes in two groups of patients undergoing primary TKA using an identical third-generation design with different conformity in the polyethylene insert.

METHODS

One hundred consecutive patients undergoing TKA because of knee osteoarthritis were randomized in two matched groups. Group A included 50 Posterior-Stabilized (PS) implants, while group B included 50 Medially Congruent (MC) implants. The surgical technique was identical: gap balancing in extension and measured resection in flexion; cruciate ligaments were always removed; the coronal alignment followed the mechanical axis and the tibial slope was set at 3° in the PS group and 5° in the MC. Oxford Knee Score (OKS) and Knee Society Score (KSS) were assessed preoperatively and at 2 year minimum follow-up. Two-sample T test statistical analysis was performed.

RESULTS

All patients were available at final follow-up: there were no preoperative statistical differences between the two groups in the average preoperative ROM (PS 112°, MC 108°; n.s.), average preoperative KSS (PS 64.4, MC 63.7; n.s.), average preoperative OKS (PS 19.6; MC 19.0; n.s.), and average BMI (PS 34.40, MC 34.60; n.s.). At final follow-up, there were no statistical differences between the two groups in the average OKS (PS 40,5; MC 41.1; n.s.) and in the average KSS (PS 161,5, MC 165,7; n.s.). We found a statistically but not clinically significant difference at final ROM: the average maximum active flexion was 120° in the PS group and 123° in the MC group (s.s.).

CONCLUSION

This study evaluated two biomechanically different polyethylene inserts in the same TKA design, showing that reducing the level of intra-articular conformity had minimal effects on PROMs and objective short-term clinical results but a potentially beneficial effect on ROM. This study suggests that, once a satisfactory intra-operative stability is obtained, the minimal level of constraint should be used.

LEVEL OF EVIDENCE

III.

Authors+Show Affiliations

Department Orthopaedic Surgery and Bioengineering, Stanford University School of Medicine, Stanford, USA. pindelli@stanford.edu. PAVAHCS, Surgical services, 1801 Miranda Ave, Palo Alto, CA, 94304, USA. pindelli@stanford.edu.Department Orthopaedic Surgery and Bioengineering, Stanford University School of Medicine, Stanford, USA. PAVAHCS, Surgical services, 1801 Miranda Ave, Palo Alto, CA, 94304, USA.Department Orthopaedic Surgery and Bioengineering, Stanford University School of Medicine, Stanford, USA. PAVAHCS, Surgical services, 1801 Miranda Ave, Palo Alto, CA, 94304, USA.Department Orthopaedic Surgery and Bioengineering, Stanford University School of Medicine, Stanford, USA. PAVAHCS, Surgical services, 1801 Miranda Ave, Palo Alto, CA, 94304, USA.Department Orthopaedic Surgery and Bioengineering, Stanford University School of Medicine, Stanford, USA. PAVAHCS, Surgical services, 1801 Miranda Ave, Palo Alto, CA, 94304, USA.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30328496

Citation

Indelli, Pier Francesco, et al. "Effect of Polyethylene Conformity On Total Knee Arthroplasty Early Clinical Outcomes." Knee Surgery, Sports Traumatology, Arthroscopy : Official Journal of the ESSKA, vol. 27, no. 4, 2019, pp. 1028-1034.
Indelli PF, Risitano S, Hall KE, et al. Effect of polyethylene conformity on total knee arthroplasty early clinical outcomes. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1028-1034.
Indelli, P. F., Risitano, S., Hall, K. E., Leonardi, E., & Migliore, E. (2019). Effect of polyethylene conformity on total knee arthroplasty early clinical outcomes. Knee Surgery, Sports Traumatology, Arthroscopy : Official Journal of the ESSKA, 27(4), 1028-1034. https://doi.org/10.1007/s00167-018-5170-5
Indelli PF, et al. Effect of Polyethylene Conformity On Total Knee Arthroplasty Early Clinical Outcomes. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1028-1034. PubMed PMID: 30328496.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of polyethylene conformity on total knee arthroplasty early clinical outcomes. AU - Indelli,Pier Francesco, AU - Risitano,Salvatore, AU - Hall,Kimberly E, AU - Leonardi,Erika, AU - Migliore,Eleonora, Y1 - 2018/10/17/ PY - 2018/04/06/received PY - 2018/09/21/accepted PY - 2018/10/18/pubmed PY - 2019/5/22/medline PY - 2018/10/18/entrez KW - Gap balancing KW - Knee KW - MC KW - Medial pivot KW - Polyethylene KW - Results KW - TKA KW - Total knee arthroplasty SP - 1028 EP - 1034 JF - Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA JO - Knee Surg Sports Traumatol Arthrosc VL - 27 IS - 4 N2 - PURPOSE: Total knee arthroplasty is a successful procedure in treating subjects with end-stage knee osteoarthritis. The objective of this matched study was to evaluate subjective patient satisfaction and clinical and radiological outcomes in two groups of patients undergoing primary TKA using an identical third-generation design with different conformity in the polyethylene insert. METHODS: One hundred consecutive patients undergoing TKA because of knee osteoarthritis were randomized in two matched groups. Group A included 50 Posterior-Stabilized (PS) implants, while group B included 50 Medially Congruent (MC) implants. The surgical technique was identical: gap balancing in extension and measured resection in flexion; cruciate ligaments were always removed; the coronal alignment followed the mechanical axis and the tibial slope was set at 3° in the PS group and 5° in the MC. Oxford Knee Score (OKS) and Knee Society Score (KSS) were assessed preoperatively and at 2 year minimum follow-up. Two-sample T test statistical analysis was performed. RESULTS: All patients were available at final follow-up: there were no preoperative statistical differences between the two groups in the average preoperative ROM (PS 112°, MC 108°; n.s.), average preoperative KSS (PS 64.4, MC 63.7; n.s.), average preoperative OKS (PS 19.6; MC 19.0; n.s.), and average BMI (PS 34.40, MC 34.60; n.s.). At final follow-up, there were no statistical differences between the two groups in the average OKS (PS 40,5; MC 41.1; n.s.) and in the average KSS (PS 161,5, MC 165,7; n.s.). We found a statistically but not clinically significant difference at final ROM: the average maximum active flexion was 120° in the PS group and 123° in the MC group (s.s.). CONCLUSION: This study evaluated two biomechanically different polyethylene inserts in the same TKA design, showing that reducing the level of intra-articular conformity had minimal effects on PROMs and objective short-term clinical results but a potentially beneficial effect on ROM. This study suggests that, once a satisfactory intra-operative stability is obtained, the minimal level of constraint should be used. LEVEL OF EVIDENCE: III. SN - 1433-7347 UR - https://www.unboundmedicine.com/medline/citation/30328496/Effect_of_polyethylene_conformity_on_total_knee_arthroplasty_early_clinical_outcomes_ L2 - https://dx.doi.org/10.1007/s00167-018-5170-5 DB - PRIME DP - Unbound Medicine ER -