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Ollivier B, Wakelin E, Plaskos C, Vandenneucker H, Luyckx T. Widening of tibial resection boundaries increases the rate of femoral component valgus and internal rotation in functionally aligned TKA. Knee Surg Sports Traumatol Arthrosc 2024; 32:953-962. [PMID: 38444096 DOI: 10.1002/ksa.12118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 02/12/2024] [Accepted: 02/15/2024] [Indexed: 03/07/2024]
Abstract
PURPOSE The 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). METHODS A 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. RESULTS The 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. CONCLUSION Extending 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 EVIDENCE Level IV.
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Affiliation(s)
- Britt Ollivier
- Department of Orthopaedics, University Hospitals Leuven, Leuven, Belgium
| | | | | | - Hilde Vandenneucker
- Department of Orthopaedics, University Hospitals Leuven, Leuven, Belgium
- Department of Development and Regeneration, KU Leuven, University of Leuven, Leuven, Belgium
| | - Thomas Luyckx
- Department of Orthopaedic Surgery, AZ Delta, Roeselare, Belgium
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Murgier J, Clatworthy M. Variable rotation of the femur does not affect outcome with patient specific alignment navigated balanced TKA. Knee Surg Sports Traumatol Arthrosc 2022; 30:517-526. [PMID: 32783080 DOI: 10.1007/s00167-020-06226-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/07/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE Excessive internal and external rotation of the femoral component has been associated with poor outcome with a measured-resection neutral mechanical alignment TKA. This technique assumes that every tibia is in 3° of varus so the femoral component is placed in 3° of external rotation relative to the posterior condylar axis to enable a balanced flexion gap. This is not the case as there is wide variability in the bony anatomy and soft tissue envelope of the knee so flexion imbalance may occur. A patient-specific alignment navigated balanced TKA technique was performed whereby the tibia is cut anatomically up to 3° of varus, then a ligament tensor is used to determine the optimal femoral component position for a balanced TKA. This results in variable femoral rotation. The hypothesis is that matching the femoral component rotation to the patient's anatomic tibial cut and soft tissue envelope will not affect clinical outcome METHODS: In a single surgeon series 287 consecutive varus aligned TKA's were performed using this technique with an Attune cruciate retaining fixed bearing TKA with an anatomic patella resurfacing. The angle between the posterior femoral cuts and the posterior condylar axis was collected using Brainlab software. Functional scores were collected prospectively preoperatively and at two years. The variable femoral component rotation was correlated with and compared with the functional outcome scores. RESULTS The femoral rotation varied from 7° of internal rotation to 8°of external rotation relative to the posterior condylar axis. The mean rotation was 1.1° of external rotation. There was no significant difference in the Oxford score, WOMAC score, Forgotten Knee Score, KOOS Joint Replacement score or Patient Satisfaction in respect to the variable femoral rotation relative to the posterior condylar axis. CONCLUSION When a more anatomic-balanced TKA technique is used variable femoral rotation will not affect clinical outcome at two years LEVEL OF EVIDENCE: II Prospective Cohort Study.
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Affiliation(s)
- Jérôme Murgier
- Orthopaedic Department, Aguiléra Private Clinic, Ramsey Santé, Biarritz, France
| | - Mark Clatworthy
- Department of Orthopaedics, Middlemore Hospital, 100 Hospital Rd, Otahuhu, Auckland, 2025, New Zealand.
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Yapp LZ, Robinson PG, Clement ND, Scott CEH. Total Knee Arthroplasty and Intra-Articular Pressure Sensors: Can They Assist Surgeons with Intra-Operative Decisions? Curr Rev Musculoskelet Med 2021; 14:361-368. [PMID: 34962638 PMCID: PMC8733123 DOI: 10.1007/s12178-021-09724-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/22/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Soft tissue imbalance, presenting as instability or stiffness, is an important cause of revision total knee arthroplasty (TKA). Traditional methods of determining soft tissue balance of the knee lack precision and are not reliable between operators. Use of intra-operative pressure sensors offers the potential to identify and avoid soft tissue imbalance following TKA. This review aims to summarise the literature supporting the clinical indication for the use of intra-articular pressure sensors during TKA. RECENT FINDINGS Analytical validation studies suggest that intra-operative pressure sensors demonstrate 'moderate' to 'good' intra-observer reliability and 'good' to 'excellent' interobserver reliability throughout the flexion arc. However, there are important errors associated with measurements when devices are used out-with the stated guidelines and clinicians should be aware of the limitations of these devices in isolation. Current evidence regarding patient benefit is conflicting. Despite positive early results, several prospective studies have subsequently failed to demonstrate significant differences in overall survival, satisfaction, and patient-reported outcome measures within 1 year of surgery. Surgeon-defined soft tissue stability appears to be significantly different from the absolute pressures measured by the intra-operative sensor. Whilst it could be argued that this confirms the need for intra-articular sensor guidance in TKA; the optimal 'target' balance remains unclear and the relationship with outcome in patients is not determined. Future research should (1) identify a suitable reference standard for comparison; (2) improve the accuracy of the sensor outputs; and (3) demonstrate that sensor-assisted TKA leads to patient benefit in patient-reported outcome measures and/or enhanced implant survival.
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Affiliation(s)
- Liam Z. Yapp
- Department of Orthopaedics, Deanery of Clinical Sciences, University of Edinburgh, Chancellors Building, 49 Little France Crescent, Edinburgh, EH16 4SB UK
- Department of Trauma & Orthopaedic Surgery, Royal Infirmary of Edinburgh, NHS Lothian, 51 Little France Crescent, Edinburgh, EH16 4SY UK
| | - Patrick G. Robinson
- Department of Orthopaedics, Deanery of Clinical Sciences, University of Edinburgh, Chancellors Building, 49 Little France Crescent, Edinburgh, EH16 4SB UK
- Department of Trauma & Orthopaedic Surgery, Royal Infirmary of Edinburgh, NHS Lothian, 51 Little France Crescent, Edinburgh, EH16 4SY UK
| | - Nicholas D. Clement
- Department of Orthopaedics, Deanery of Clinical Sciences, University of Edinburgh, Chancellors Building, 49 Little France Crescent, Edinburgh, EH16 4SB UK
- Department of Trauma & Orthopaedic Surgery, Royal Infirmary of Edinburgh, NHS Lothian, 51 Little France Crescent, Edinburgh, EH16 4SY UK
| | - Chloe E. H. Scott
- Department of Orthopaedics, Deanery of Clinical Sciences, University of Edinburgh, Chancellors Building, 49 Little France Crescent, Edinburgh, EH16 4SB UK
- Department of Trauma & Orthopaedic Surgery, Royal Infirmary of Edinburgh, NHS Lothian, 51 Little France Crescent, Edinburgh, EH16 4SY UK
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Holst DC, Doan GW, Angerame MR, Roche MW, Clary CW, Dennis DA. What is the Effect of Posterior Osteophytes on Flexion and Extension Gaps in Total Knee Arthroplasty? A Cadaveric Study. Arthroplast Today 2021; 11:127-133. [PMID: 34522740 PMCID: PMC8427272 DOI: 10.1016/j.artd.2021.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 08/05/2021] [Accepted: 08/12/2021] [Indexed: 01/14/2023] Open
Abstract
Background Posterior compartment knee osteophytes may pose a challenge in achieving soft-tissue balance during total knee arthroplasty (TKA). Obtaining symmetry of flexion and extension gaps involves balance of both bony and soft-tissue structures. We hypothesize that space-occupying posteromedial femoral osteophytes affect soft-tissue balance. Methods Five cadaveric limbs were acquired. Computed tomography scans were obtained to define the osseous contours. Three-dimensionally printed, specimen-specific synthetic posterior femoral osteophytes were fabricated in 10-mm and 15-mm sizes. TKAs were implanted. Medial and lateral compartment contact forces were measured during passive knee motion using pressure-sensing technology. For each specimen, trials were completed without osteophytes and with 10-mm and 15-mm osteophytes affixed to the posteromedial femoral condyle. Contact forces were obtained at full extension, 10°, 30°, 45°, 60°, and 90° of flexion. These were recorded across each specimen in each condition for three trials. Tukey post hoc tests were used with a repeated measures ANOVA for statistical data analysis. Results The presence of posteromedial osteophytes increased asymmetric loading from full extension to 45° of flexion, with statistically significant differences observed at full extension and 30°. A reduction in lateral compartment forces was noted. The 25%-75% bounds of variability in the contact force was less than 3.5 lbs. Conclusions Posteromedial femoral osteophytes caused an asymmetric increase in medial contact forces from full extension continuing into mid-flexion. The soft-tissue imbalance created from these osteophytes supports their removal before performing ligament releases to obtain desired soft-tissue balancing during TKA.
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Affiliation(s)
- David C Holst
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC
| | - Gary W Doan
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO
| | | | | | - Chadd W Clary
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO
| | - Douglas A Dennis
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO.,Colorado Joint Replacement, Denver, CO.,Department of Orthopaedics, University of Colorado School of Medicine, Aurora, CO.,Department of Biomedical Engineering, University of Tennessee, Knoxville, TN
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Improving radiographic patello-femoral tracking in total knee arthroplasty with the use of a flexion spacer: a case-control study. Knee Surg Sports Traumatol Arthrosc 2021; 29:586-593. [PMID: 32279109 DOI: 10.1007/s00167-020-05991-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/07/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE The purpose of this study was to compare the effectiveness of a flexion spacer in the clinical and radiological outcomes of patients who underwent total knee arthroplasty (TKA) and to compare these patients to a group of patients subjected to the same type of surgery but without the use of a flexion spacer. It was hypothesized that patients who underwent TKA using a flexion spacer would have better clinical and radiological outcomes than those without a flexion spacer in both short- and medium-term follow-ups. METHODS A consecutive series of patients undergoing TKA were included, yielding 20 patients in the study group. The control group was identified from the consultant database of the senior author, yielding 21 patients who underwent the same operation. All 41 patients received a Vanguard Knee System (Zimmer-Biomet, Warsaw, Indiana, USA). Cases were defined as those patients who had undergone TKA using a flexion spacer device for gap balancing; controls were defined as patients who had undergone TKA without the support of a flexion spacer device. Patients were clinically and radiographically evaluated at two consecutive follow-ups: T1-13.1 ± 1.3 months and T2-108 ± 6 months. Clinical evaluation was performed using the Knee Society Scoring System and the Western Ontario, McMaster Universities Osteoarthritis Index score. Radiographic evaluation included the femoral angle (α), the tibial angle (β), the sagittal femoral (γ) angle and the tibial slope (δ). Furthermore, the lateral patellofemoral angle (LPFA) and the Caton-Deschamps index were evaluated. RESULTS No statistically significant clinical differences were found between the two groups at T1 and T2; moreover, the clinical outcomes of the two groups were stable between the two follow-ups, with no significant improvement or worsening. Radiographic evaluation showed no difference in the two groups between T1 and T2; the only significant radiographic difference between the two groups concerned the LPFA (both at 30° and 60°) at each follow-up, which was significantly greater in cases than in controls (p = 0.001). CONCLUSIONS The current study demonstrates that the use of a flexion spacer significantly improves radiographic patello-femoral tracking, although no significant clinical differences were found between the two groups. LEVEL OF EVIDENCE Case-control study, level III.
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Dong Y, Zhang Z, Dong W, Hu G, Wang B, Mou Z. An optimization method for implantation parameters of individualized TKA tibial prosthesis based on finite element analysis and orthogonal experimental design. BMC Musculoskelet Disord 2020; 21:165. [PMID: 32164625 PMCID: PMC7068904 DOI: 10.1186/s12891-020-3189-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/04/2020] [Indexed: 11/22/2022] Open
Abstract
Background Individualized and accurate implantation of a tibial prosthesis during total knee arthroplasty (TKA) can assist in uniformly distributing the load and reducing the polyethylene wear to obtain a long-term prosthetic survival rate, but individualized and accurate implantation of a tibial prosthesis during TKA remains challenging. The purpose of this study was to optimize and individualize the positioning parameters of a tibial prosthesis to improve its accurate implantation using a new method of finite element analysis in combination with orthogonal experimental design. Methods Ten finite element models of TKA knee joint were developed to optimize the implantation parameters (varus angle, posterior slope angle, and external rotation angle) of tibial prosthesis to reduce the peak value of the contact pressure on the polyethylene liner according to the method of finite element analysis in combination with orthogonal experimental design. The influence of implantation parameters on the peak value of the contact pressure on the polyethylene liner was evaluated based on a range analysis in orthogonal experimental design. Results The optimal implantation parameters for tibial prosthesis included 0° varus, 1° posterior slope, and 4° external rotation. Under these conditions, the peak value of the contact pressure on the polyethylene liner remained the smallest (16.37 MPa). Among the three parameters that affect the peak value of the contact pressure, the varus angle had the greatest effect (range = 6.70), followed by the posterior slope angle (range = 2.36), and the external rotation angle (range = 2.15). Conclusions The optimization method based on finite element analysis and orthogonal experimental design can guide the accurate implantation of the tibial prosthesis, reducing the peak value of the contact pressure on the polyethylene liner. This method provides new insights into the TKA preoperative plan and biomechanical decision-making for accurately implanting TKA prosthesis.
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Affiliation(s)
- Yuefu Dong
- Department of Orthopedics, The Affiliated Lianyungang Hospital of Xuzhou Medical University/the First People's Hospital of Lianyungang, Lianyungang, China
| | - Zhen Zhang
- School of Materials Engineering, Shanghai University of Engineering Science, Shanghai, China
| | - Wanpeng Dong
- School of Materials Engineering, Shanghai University of Engineering Science, Shanghai, China
| | - Guanghong Hu
- Institute of Plasticity Forming Technology & Equipment, Shanghai Jiao Tong University, Shanghai, China
| | - Bing Wang
- Department of Orthopedics, The Affiliated Lianyungang Hospital of Xuzhou Medical University/the First People's Hospital of Lianyungang, Lianyungang, China
| | - Zhifang Mou
- Department of Critical Care Medicine, The Affiliated Lianyungang Hospital of Xuzhou Medical University/the First People's Hospital of Lianyungang, No.8 Lingzhou East Road, Haizhou District, Lianyungang, 222000, China.
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Manning W, Ghosh M, Wilson I, Hide G, Longstaff L, Deehan D. Improved mediolateral load distribution without adverse laxity pattern in robot-assisted knee arthroplasty compared to a standard manual measured resection technique. Knee Surg Sports Traumatol Arthrosc 2020; 28:2835-2845. [PMID: 31352497 PMCID: PMC7471111 DOI: 10.1007/s00167-019-05631-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 07/15/2019] [Indexed: 11/28/2022]
Abstract
PURPOSE Robot-assisted total knee arthroplasty (rTKA) remains in its infancy, is expensive but offers the promise of improved kinematic performance through precise bone cuts, with minimal soft tissue disruption, based on pre-resection soft tissue behaviour. This cadaveric study examined load transfer, soft tissue performance and radiographic indices for conventional (sTKA) versus rTKA. The null hypothesis was there would be no difference between the two modes of implantation. METHODS Whole (ten) cadaveric limbs were randomised to receive either robotic (rTKA, N = 5) or conventional measured resection (sTKA, N = 5) knee arthroplasty. Laxity patterns were established using validated fixed sensors (Verasense) with manual maximum displacement for six degrees of freedom. Tibiofemoral load and contact points were determined dynamically using remote sensor technology for medial and lateral compartments through a functional arc of motion (0-110 degrees of motion). Final component position was assessed using pre- and post-implantation CT. RESULTS No significant intergroup differences for laxity were found (n.s.). The rTKA group exhibited consistently balanced mediolateral load throughout the full arc with significantly reduced overall total load across the joint (for distinct points of measurement, p < 0.05). Despite using flexion-extension and mediolateral gap balancing with measured resection, the sTKA group failed to achieve balance in at least three points of the flexion arc. Post-operative CT confirmed satisfactory component alignment with no significant differences for positioning between the two groups. CONCLUSION This work found improved load sharing for rTKA when compared to conventional surgery for same donor knees. Laxity and CT determined final component positioning was not significantly different. The work supports the contention that robot-assisted TKA delivers improved tibiofemoral load sharing in time zero studies under defined conditions but such offers the promise of improved clinical performance and reduced implant wear.
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Affiliation(s)
- William Manning
- Newcastle Surgical Training Centre Research Unit Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN UK ,Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN UK
| | - Milton Ghosh
- Newcastle Surgical Training Centre Research Unit Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN UK ,Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN UK
| | - Ian Wilson
- Institute of Genetic Medicine, Newcastle University International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
| | - Geoff Hide
- Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN UK
| | - Lee Longstaff
- University Hospital of North Durham, Durham, DH1 5TW England, UK
| | - David Deehan
- Newcastle Surgical Training Centre Research Unit Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN, UK. .,Freeman Hospital, High Heaton, Newcastle upon Tyne, NE7 7DN, UK.
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A load-measuring device can achieve fine-tuning of mediolateral load at knee arthroplasty but may lead to a more lax knee state. Knee Surg Sports Traumatol Arthrosc 2019; 27:2238-2250. [PMID: 30288569 PMCID: PMC6609829 DOI: 10.1007/s00167-018-5164-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 09/25/2018] [Indexed: 12/30/2022]
Abstract
PURPOSE A balanced knee arthroplasty should optimise survivorship and performance. Equilibration of medial and lateral femorotibial load requires guided judicious pericapsular ligament release. The null hypothesis was that there would be no difference between use of a tensiometer device and a remote load sensor final load transfer across the joint through functional arc of motion. METHODS A cadaveric study, using eight knees, was performed to define the impact of an established gap distraction device against load sensor-aimed soft tissue release in a TKA setting. Using validated measures of laxity in six degrees of freedom and true real-time load sensing four states were examined: native knee, TKA using spacer blocks (TKA), TKA with soft tissue release aided by a monogram tensiometer (TKA-T) and finally where load across the tibiofemoral articulation remains unbalanced final soft tissue release using a sensor device (TKA-OS). RESULTS The laxity pattern was equivalent for TKA-T and TKA-OS. However, in only four of these seven knees despite the tensiometer confirming equivalence of rectangular flexion-extension gap dimensions and centralisation of collateral ligament distraction, there remained a > 15lb medial to lateral load difference for at least one point of the flexion arc. This was corrected by further final soft tissue release guided by the OS sensor device in the final three knees. CONCLUSION Tensiometer-guided soft tissue release at two points of flexion failed to achieve balance for three out of seven knee arthroplasty procedures. Sensor technology guided final soft tissue balancing to equilibrate load across the joint through full arc of motion. This work argues for the role of continuous sensor readings to guide the soft tissue balancing during total knee arthroplasty.
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Hollander DB, Yoshida S, Tiwari U, Saladino A, Nguyen M, Boudreaux B, Hadley B. Dynamic Analysis of Vibration, Muscle Firing, and Force as a Novel Model for Non-Invasive Assessment of Joint Disruption in the knee: A Multiple Case Report. Open Neuroimag J 2018. [DOI: 10.2174/1874440001812010120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We present a new method for understanding knee pathology through non-invasive techniques. The combination of electromyography (EMG), vibroarthrographic (VAG), and force analysis in proposed to examine the force transfer between unhealthy and healthy knees. A multiple case report is presented to demonstrate the technique and its potential application for future study. The comparison of four individuals’ knee characteristics will be explained using this innovative methodology.
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Affiliation(s)
- N D Clement
- Department of Orthopaedics, Freeman Hospital, High Heaton, Newcastle-upon-Tyne, UK
| | - D J Deehan
- Department of Orthopaedics, Freeman Hospital, High Heaton, Newcastle-upon-Tyne, UK
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Riley J, Roth JD, Howell SM, Hull ML. Internal-external malalignment of the femoral component in kinematically aligned total knee arthroplasty increases tibial force imbalance but does not change laxities of the tibiofemoral joint. Knee Surg Sports Traumatol Arthrosc 2018; 26:1618-1628. [PMID: 29181558 DOI: 10.1007/s00167-017-4776-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 10/30/2017] [Indexed: 01/15/2023]
Abstract
PURPOSE The purposes of this study were to quantify the increase in tibial force imbalance (i.e. magnitude of difference between medial and lateral tibial forces) and changes in laxities caused by 2° and 4° of internal-external (I-E) malalignment of the femoral component in kinematically aligned total knee arthroplasty. Because I-E malalignment would introduce the greatest changes to the articular surfaces near 90° of flexion, the hypotheses were that the tibial force imbalance would be significantly increased near 90° flexion and that primarily varus-valgus laxity would be affected near 90° flexion. METHODS Kinematically aligned TKA was performed on ten human cadaveric knee specimens using disposable manual instruments without soft tissue release. One 3D-printed reference femoral component, with unmodified geometry, was aligned to restore the native distal and posterior femoral joint lines. Four 3D-printed femoral components, with modified geometry, introduced I-E malalignments of 2° and 4° from the reference component. Medial and lateral tibial forces were measured from 0° to 120° flexion using a custom tibial force sensor. Bidirectional laxities in four degrees of freedom were measured from 0° to 120° flexion using a custom load application system. RESULTS Tibial force imbalance increased the greatest at 60° flexion where a regression analysis against the degree of I-E malalignment yielded sensitivities (i.e. slopes) of 30 N/° (medial tibial force > lateral tibial force) and 10 N/° (lateral tibial force > medial tibial force) for internal and external malalignments, respectively. Valgus laxity increased significantly with the 4° external component with the greatest increase of 1.5° occurring at 90° flexion (p < 0.0001). CONCLUSION With the tibial component correctly aligned, I-E malalignment of the femoral component caused significant increases in tibial force imbalance. Minimizing I-E malalignment lowers the increase in the tibial force imbalance. By keeping the resection thickness of each posterior femoral condyle to within ± 0.5 mm of the thickness of the respective posterior region of the femoral component, the increase in imbalance can be effectively limited to 38 N. Generally laxities were unaffected within the ± 4º range tested indicating that instability is not a clinical concern and that manual testing of laxities is not useful to detect I-E malalignment.
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Affiliation(s)
- Jeremy Riley
- Biomedical Engineering Graduate Group, University of California, Davis, USA
| | - Joshua D Roth
- Biomedical Engineering Graduate Group, University of California, Davis, USA
| | - Stephen M Howell
- Department of Biomedical Engineering, University of California, Davis, USA
| | - Maury L Hull
- Department of Biomedical Engineering, University of California, Davis, USA.
- Department of Mechanical Engineering, University of California, Davis, USA.
- Department of Orthopaedic Surgery, University of California, Davis, USA.
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