Undercoverage of lateral trochlear resection is correlated with the tibiofemoral alignment parameters in kinematically aligned TKA: a retrospective clinical study

Abstract Background A mismatch between the femoral component and trochlear resection surface is observed in kinematically aligned total knee arthroplasty (KA-TKA) when conventional prostheses are employed. This mismatch is mainly manifested in the undercoverage of the lateral trochlear resection surface. The aim of the present study was to assess the relationship between the mismatch and the alignment parameters of the tibiofemoral joint. Methods Forty-five patients (52 knees) who underwent KA-TKA in our hospital were included. Patient-specific instrumentation was used in 16 patients (16 knees), and conventional instruments with calipers and other special tools were employed in the other 29 patients (36 knees). The widths of the exposed resection bone surface at the middle (MIDexposure) and distal (DISexposure) levels on the lateral trochlea were measured as dependent variables, whereas the hip-knee-ankle angle (HKAA), mechanical lateral distal femoral angle (mLDFA), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA) and transepicondylar axis angle (TEAA) were measured as independent variables. Correlation analysis and subsequent linear regression were conducted among the dependent variables and various alignment parameters of the tibiofemoral joint. Results The incidence of undercoverage of the lateral trochlear resection surface was 86.5 % with MIDexposure and DISexposure values of 2.3 (0–6 mm) and 2.0 (0–5 mm), respectively. The widths of the two levels of exposed bone resection were significantly correlated with mLDFA and HKAA but were not related to TEAA. Conclusions The undercoverage of the trochlear resection surface in KA-TKA is mainly correlated with the degree of valgus of the distal femoral joint line. The current study suggests that this correlation should be considered in the development of KA-specific prostheses.

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The Insufficient Coverage of Lateral Trochlear Resection is Correlated to the Tibiofemoral Alignment Parameters in Kinematically Aligned TKA: A Retrospective Clinical Study

10.21203/rs.3.rs-89190/v1 ◽

2020 ◽

Author(s):

Zhiwei Wang ◽

Liang Wen ◽

Liang Zhang ◽

Desi Ma ◽

Xiang Dong ◽

...

Keyword(s):

Joint Line ◽

Patient Specific ◽

Bone Surface ◽

Transepicondylar Axis ◽

Tibiofemoral Joint ◽

Joint Line Convergence Angle ◽

Retrospective Clinical Study ◽

Dependent Variables ◽

Total Knee ◽

Tibiofemoral Alignment

Abstract Background: The mismatching of the femoral component and trochlear resection surface is very common in kinematically aligned total knee arthroplasty (KA-TKA) when conventional prostheses are employed. This mismatching is mainly manifested in the insufficient coverage of the bone cut surface of the lateral trochlea. The aim of present study is to explore whether this mismatch is related to the alignment parameters of the tibiofemoral joint. Methods: 45 patients (52 knees) who underwent KA-TKA in our hospital were included. There were 16 patients (16 knees) received surgery using patient specific instrumentations, and conventional instruments with caliper and other special tools were employed in the other 29 patients (36 knees). The widths of exposed resection bone surface at the middle (MIDexposure) and distal (INFexposure) levels on the lateral trochlear were measured as dependent variables, while the hip-knee-ankle (HKA) angle, mechanical lateral distal femoral angle (mLDFA), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA) and transepicondylar axis angle (TEAA) were measured as independent variables. Correlation analysis and subsequent linear regression were conducted among the dependent variables and various alignment parameters of the tibiofemoral joint. Results: The incidence of insufficient coverage of the lateral trochlear cut bone surface was 86.5%, with MIDexposure and INFexposure being 2.3 (0-6mm) and 2.0 (0-5mm), respectively. The widths of two levels of exposed bone resection were significantly correlated to mLDFA and HKA, but were not related to TEAA. Conclusions: the insufficient coverage of trochlear resection surface in KA-TKA is negatively correlated with the degrees of valgus of the distal femoral joint line and the degrees of varus of the knee. The present study suggest that in the development of KA-specific prostheses, attention should be paid to the effects of tibiofemoral alignment parameters on the prosthetic matching of the trochlear resection surface.

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Surgeon Dominated Design Can Improve the Accuracy of Patient-specific Instruments in Kinematically Aligned TKA

10.21203/rs.3.rs-109191/v1 ◽

2020 ◽

Author(s):

Zhiwei Wang ◽

Liang Wen ◽

Liang Zhang ◽

Desi Ma ◽

Xiang Dong ◽

...

Keyword(s):

Joint Line ◽

Patient Specific ◽

Group 14 ◽

Bone Resection ◽

Patient Specific Instrumentation ◽

Improve Accuracy ◽

Before And After ◽

Patient Specific Instruments ◽

Total Knee ◽

Line P

Abstract Precise bone resection is mandatory for kinematically aligned total knee arthroplasty（KA-TKA). Patient-specific instrumentation (PSI) has been applied to improve the accuracy of bone resection in TKA for many years. The purpose of this study was to investigate whether surgeons’ domination in PSI design can improve accuracy in KA-TKA. A total of 24 patients (24 knees) who underwent KA-TKA in our institution were assigned into engineer designed PSI group (10 knees) and surgeon designed PSI group (14 knees). The bone resection discrepancies of every key facets were used to evaluate the accuracy of PSI in bone resection, while the absolute differences of joint line orientation before and after surgery were used to evaluate the accuracy of PSI in joint line restoration. The overall discrepancy of bone resection was reduced by surgeon designed PSI compared to engineer designed PSI by 0.33mm (P<0.001). Surgeon designed PSI could reduce the outliers in terms of relative discrepancies in bone resection as well. Moreover, surgeon designed PSI could significantly improve the accuracy of PSI in the restoration of the joint line (p=0.01). This study indicate that the dominance of surgeons in both PSI design and subsequent surgical operation should be emphasized in efforts to improve the accuracy of PSI.

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