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MacDessi SJ, van de Graaf VA, Wood JA, Griffiths-Jones W, Bellemans J, Chen DB. Not all knees are the same. Bone Joint J 2024; 106-B:525-531. [PMID: 38821506 DOI: 10.1302/0301-620x.106b6.bjj-2023-1292.r1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
The aim of mechanical alignment in total knee arthroplasty is to align all knees into a fixed neutral position, even though not all knees are the same. As a result, mechanical alignment often alters a patient's constitutional alignment and joint line obliquity, resulting in soft-tissue imbalance. This annotation provides an overview of how the Coronal Plane Alignment of the Knee (CPAK) classification can be used to predict imbalance with mechanical alignment, and then offers practical guidance for bone balancing, minimizing the need for soft-tissue releases.
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Affiliation(s)
- Samuel J MacDessi
- CPAK Research Group, Sydney, Australia
- School of Clinical Medicine, University of NSW Medicine and Health, Sydney, Australia
- Sydney Knee Specialists, Kogarah, Australia
| | | | - Jil A Wood
- Sydney Knee Specialists, Kogarah, Australia
| | | | - Johan Bellemans
- CPAK Research Group, Sydney, Australia
- University Hasselt, ZOL Hospitals Genk, ArthroClinic Leuven, Leuven, Belgium
| | - Darren B Chen
- CPAK Research Group, Sydney, Australia
- Sydney Knee Specialists, Kogarah, Australia
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Zou D, Ling Z, Tan J, Zheng N, Dimitriou D, Chen Y, Tsai TY. Medial stability and lateral flexibility of the collateral ligaments during mid-range flexion in medial-pivot total knee arthroplasty patients demonstrates favorable postoperative outcomes. Knee Surg Sports Traumatol Arthrosc 2023; 31:3734-3744. [PMID: 36670261 DOI: 10.1007/s00167-023-07307-0] [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: 10/18/2022] [Accepted: 12/26/2022] [Indexed: 01/22/2023]
Abstract
PURPOSE The objectives of the present study were to investigate the length change in different bundles of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) during lunge, and to evaluate their association with Knee Society Score (KSS) following medial-pivot total knee arthroplasty (MP-TKA). METHODS Patients with unilateral MP-TKA knees performed a bilateral single-leg lunge under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The contralateral non-operated knees were used as the control group. The attachment sites of the sMCL and LCL were marked to calculate the 3D wrapping length. The sMCL and LCL were divided into anterior, intermediate, and posterior portions (aMCL, iMCL, pMCL, aLCL, iLCL, pLCL). Correlations between lengths/elongation rate of ligament bundles from full extension to 100° flexion and the KSS were examined. RESULTS The sMCL and LCL demonstrated relative stability in length at low flexion, but sMCL length decreased whereas LCL increased with further flexion on operated knees. The sMCL length increased at low flexion and remained stable with further flexion, while the LCL length decreased with flexion on the contralateral non-operated knees. The lengths of aMCL, iMCL, and pMCL showed moderate (0.5 < r < 0.7, p < 0.05) negative correlations with the KSS, and the lengths of aLCL, iLCL, and pLCL were positively correlated with the KSS at mid flexion on operated knees (p < 0.05). The elongation rates of aLCL, iLCL, and pLCL were negatively correlated with the KSS at high flexion on operated knees (p < 0.05). However, no significant correlations between the length of different bundles of sMCL or LCL with KSS were found on contralateral non-operated knees. CONCLUSIONS The elongation pattern of sMCL/LCL on MP-TKA knees showed differences with contralateral non-operated knees. The sMCL is tense at low to middle flexion and relaxed at high flexion, while LCL is relaxed at low to middle flexion and tense at high flexion following MP-TKA. Medial stability and proper lateral flexibility during mid flexion were associated with favorable postoperative outcomes in MP-TKA patients. In contrast, lateral relaxation at deep flexion should be avoided when applying soft-tissue balancing in MP-TKA. LEVEL OF EVIDENCE Level III.
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Affiliation(s)
- Diyang Zou
- School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University; Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai, China
- Shanghai Key Laboratory of Orthopaedic Implants & Clinical Translation R&D Center of 3D Printing Technology, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhi Ling
- School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University; Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai, China
- Shanghai Key Laboratory of Orthopaedic Implants & Clinical Translation R&D Center of 3D Printing Technology, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jiaqi Tan
- Department of Orthopedics, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Nan Zheng
- School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University; Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai, China
- Shanghai Key Laboratory of Orthopaedic Implants & Clinical Translation R&D Center of 3D Printing Technology, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dimitris Dimitriou
- Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, CH-8008, Zürich, Switzerland.
| | - Yunsu Chen
- Department of Orthopedics, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China.
| | - Tsung-Yuan Tsai
- School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University; Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai, China.
- Shanghai Key Laboratory of Orthopaedic Implants & Clinical Translation R&D Center of 3D Printing Technology, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Fabrizio M, Edoardo B, Niccolò G, Roberto C, Bernardo I. How reproducible are clinical measurements in robotic knee surgery? J Exp Orthop 2023; 10:32. [PMID: 36961581 PMCID: PMC10039133 DOI: 10.1186/s40634-023-00582-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 01/30/2023] [Indexed: 03/25/2023] Open
Abstract
PURPOSE Robotic-assisted surgery has been recently introduced to improve biomechanical restoration, and thus better clinical and functional outcomes, after knee joint arthroplasty operations. Robotic-assisted uni-compartmental knee arthroplasty (UKA) aims indeed to improve surgical bone resection and alignment accuracy, optimized component positioning and knee balancing, relying on a series of calibration measurements performed during the surgery. These advantages focus therefore on improving the reproducibility of UKA surgeries, reducing (if not eliminating) eventual differences among high- and low-volume surgeons. The purpose of this study is to investigate and quantify the reproducibility of in-vivo measurements performed with a robotic system: the intra- and inter-observer variability of a series of measurements was therefore analyzed and compared among differently experienced operators. METHODS Five patients were analyzed and underwent robotic-assisted UKA using a semi-active robotic system. Three different observers with different experience levels were involved to independently perform the measurements of two parameters of the preoperative knee (Hip-Knee-Ankle angle [HKAa], Internal-External Rotation) at different degrees of knee flexion. Inter-observer and intra-observer comparisons were performed. RESULTS The average variability in the measurements obtained from the intra-observer and inter-observer comparisons were always < 0.68° for HKAa and < 2.59° for internal-external rotation, and the ICCs showed excellent agreement (> 0.75) for most cases and good agreement (> 0.60) in the remaining ones. CONCLUSION This study demonstrated high reproducibility of the measurements obtainable in clinical environment with the robotic system. The inter-observer results furthermore showed that the level of confidence with the robotic system is not significantly influencing the measurement.
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Affiliation(s)
- Matassi Fabrizio
- Orthopedic Clinic, University of Florence, AOU Careggi, Florence, Italy
| | - Bori Edoardo
- BEAMS Department (Bio Electro and Mechanical Systems), École Polytechnique de Bruxelles, Université Libre de Bruxelles, Bruxelles, Belgium.
| | - Giabbani Niccolò
- Orthopedic Clinic, University of Florence, AOU Careggi, Florence, Italy
| | - Civinini Roberto
- Orthopedic Clinic, University of Florence, AOU Careggi, Florence, Italy
| | - Innocenti Bernardo
- BEAMS Department (Bio Electro and Mechanical Systems), École Polytechnique de Bruxelles, Université Libre de Bruxelles, Bruxelles, Belgium
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4
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Young SW, Gavin W C, Esposito CI, Carter M, Walker M. The Effect of Minor Adjustments to Tibial and Femoral Component Position on Soft Tissue Balance in Robotic Total Knee Arthroplasty. J Arthroplasty 2023; 38:S238-S245. [PMID: 36933677 DOI: 10.1016/j.arth.2023.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 03/20/2023] Open
Abstract
BACKGROUND Ideal goals for alignment and balance in total knee arthroplasty (TKA) remain controversial. We aimed to compare initial alignment and balance using mechanical alignment (MA) and kinematic alignment (KA) techniques, and to analyze the percentage of knees that could achieve balance using limited adjustments to component position. METHODS Prospective data on 331 primary robotic TKAs (115 MA and 216 KA) were analyzed. Medial and lateral virtual gaps were recorded in both flexion and extension. A computer algorithm was used to calculate potential (theoretical) implant alignment solutions to achieve balance within 1 millimeter (mm) without soft tissue release given an alignment philosophy (MA or KA), angular boundaries (±1, ±2, or ±3°), and gap targets (equal gaps or lateral laxity allowed). The percentage of knees that could theoretically achieve balance was compared. RESULTS Less than 5% of TKAs were initially balanced. Limited adjustments to component position increased the percentage of TKAs that could be balanced in a graduated manner, with no difference between MA and KA start points: adjustments of ±1 (10 vs 6% P=0.17), or ±2 (42 vs 39% P=0.61) or of ±3 (54 vs 51% P=0.66). A higher percentage of TKAs could be balanced when a greater range for lateral gap laxity was allowed. Balancing from KA resulted in increased joint line obliquity in the final implant alignment. CONCLUSION A high percentage of TKAs can be balanced without soft-tissue release using minor adjustments to component position. Surgeons should consider the relationship between alignment and balance goals when optimizing component positioning in TKA.
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Affiliation(s)
- Simon W Young
- Department of Orthopaedic Surgery, North Shore Hospital, Auckland, New Zealand.
| | - Clark Gavin W
- Department of Orthopaedic Surgery, St. John of God Subiaco Hospital, Perth, Australia
| | | | | | - Matthew Walker
- Department of Orthopaedic Surgery, North Shore Hospital, Auckland, New Zealand
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Shamritsky DZ, Berube EE, Sapountzis N, Diaz A, Krell EC, Wright TM, Parides M, Westrich GH, Mayman DJ, Sculco PK, Chalmers BP, Imhauser CW. Novel Arthrometer for Quantifying In Vivo Knee Laxity in Three Planes Following Total Knee Arthroplasty. J Arthroplasty 2023; 38:S190-S195. [PMID: 36813213 DOI: 10.1016/j.arth.2023.02.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/08/2023] [Accepted: 02/11/2023] [Indexed: 02/24/2023] Open
Abstract
BACKGROUND Knee instability is a leading cause of dissatisfaction following total knee arthroplasty (TKA). Instability can involve abnormal laxity in multiple directions including varus-valgus (VV) angulation, anterior-posterior (AP) translation, and internal-external rotation (IER). No existing arthrometer objectively quantifies knee laxity in all three of these directions. The study objectives were to verify the safety and assess reliability of a novel multiplanar arthrometer. METHODS The arthrometer utilized a five degree-of-freedom instrumented linkage. Two examiners each conducted two tests on the leg that had received a TKA of 20 patients (mean age 65 years (range, 53-75); 9 men, 11 women), with nine and eleven distinct patients tested at 3-month and 1-year postoperative time points, respectively. AP forces from -10 to 30 Newtons, VV moments of ±3 Newton-meters, and IER moments of ±2.5 Newton-meters were applied to each subject's replaced knee. Severity and location of knee pain during testing were assessed using a visual analog scale. Intraexaminer and interexaminer reliabilities were characterized using intraclass correlation coefficients. RESULTS All subjects successfully completed testing. Pain during testing averaged 0.7 (out of possible 10; range, 0-2.5). Intraexaminer reliability was >0.77 for all loading directions and examiners. Interexaminer reliability and 95% confidence intervals were 0.85 (0.66-0.94), 0.67 (0.35-0.85), and 0.54 (0.16-0.79) in the VV, IER, and AP directions, respectively. CONCLUSION The novel arthrometer was safe for evaluating AP, VV, and IER laxities in subjects who had received TKA. This device could be used to examine relationships between laxity and patient perceptions of knee instability.
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Affiliation(s)
- David Z Shamritsky
- Department of Biomechanics, Hospital for Special Surgery, New York, New York
| | - Erin E Berube
- Department of Biomechanics, Hospital for Special Surgery, New York, New York
| | - Nicolas Sapountzis
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - Allison Diaz
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - Ethan C Krell
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - Timothy M Wright
- Department of Biomechanics, Hospital for Special Surgery, New York, New York
| | - Michael Parides
- Department of Biostatistics and Bioinformatics, Hospital for Special Surgery, New York, New York
| | - Geoffrey H Westrich
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - David J Mayman
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - Peter K Sculco
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - Brian P Chalmers
- Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York
| | - Carl W Imhauser
- Department of Biomechanics, Hospital for Special Surgery, New York, New York
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MacDessi SJ, Oussedik S, Abdel MP, Victor J, Pagnano MW, Haddad FS. The language of knee alignment : updated definitions and considerations for reporting outcomes in total knee arthroplasty. Bone Joint J 2023; 105-B:102-108. [PMID: 36722056 DOI: 10.1302/0301-620x.105b2.bjj-2022-1345] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Orthopaedic surgeons are currently faced with an overwhelming number of choices surrounding total knee arthroplasty (TKA), not only with the latest technologies and prostheses, but also fundamental decisions on alignment philosophies. From 'mechanical' to 'adjusted mechanical' to 'restricted kinematic' to 'unrestricted kinematic' - and how constitutional alignment relates to these - there is potential for ambiguity when thinking about and discussing such concepts. This annotation summarizes the various alignment strategies currently employed in TKA. It provides a clear framework and consistent language that will assist surgeons to compare confidently and contrast the concepts, while also discussing the latest opinions about alignment in TKA. Finally, it provides suggestions for applying consistent nomenclature to future research, especially as we explore the implications of 3D alignment patterns on patient outcomes.Cite this article: Bone Joint J 2023;105-B(2):102-108.
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Affiliation(s)
- Samuel J MacDessi
- Sydney Knee Specialists, Sydney, Australia.,The University of New South Wales, Sydney, Australia
| | | | - Matthew P Abdel
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Jan Victor
- Department of Orthopaedics, University Hospital of Ghent, Ghent, Belgium
| | - Mark W Pagnano
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Fares S Haddad
- University College London Hospitals, London, UK.,The Bone & Joint Journal, London, UK
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Mehta N, Burnett RA, Kahlenberg CA, Miller R, Chalmers B, Cross MB. Mid-Flexion Instability After Total Knee Arthroplasty: Diagnosis, Implant Design, and Outcomes. Orthopedics 2023; 46:e13-e19. [PMID: 35876775 DOI: 10.3928/01477447-20220719-01] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Mid-flexion instability (MFI) in total knee arthroplasty refers to a distinct clinical entity where the knee is stable at full extension and 90° of flexion, but unstable somewhere between these 2 points. The presentation of MFI is often vague, and studies defining objective clinical or intraoperative measurements are limited. In this review, we aim to properly define the condition, describe diagnostic criteria and risk factors contributing to MFI, review current implant design, and present outcomes of revision surgery performed for MFI. [Orthopedics. 2023;46(1):e13-e19.].
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A single type of varus knee does not exist: morphotyping and gap analysis in varus OA. Knee Surg Sports Traumatol Arthrosc 2022; 30:2600-2608. [PMID: 34414473 DOI: 10.1007/s00167-021-06688-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 07/29/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE To achieve a higher level of satisfaction in patients having undergone Total Knee Arthroplasty (TKA), a more personalized approach has been discussed recently. It can be assumed that a more profound knowledge of bony morphology and ligamentous situation would be beneficial. While CT/MRI can give 3D information on bone morphology, the understanding of the ligamentous situation in different flexion angles is still incomplete. In this study, the dynamic gap widths of a large number of varus knees were assessed in various flexion angles, to find out whether all varus knees behave similar or have more individual soft tissue patterns. Additionally, it was investigated whether the amount of varus deformity or other patient factors have an effect on joint gap widths. METHODS A series of 1000 consecutive TKA patients, including their CAS data and patient records were analyzed. Joint gap widths in multiple flexion angles (0°, 30°, 60°, 90°) were measured in mm and differences between the joint gaps were compared. A "standard" varus knee was defined as follows: (1) Lateral extension gap greater than medial, (2) lateral flexion gap greater than medial, and (3) flexion gap greater than extension gap. The percentage of fulfillment was tested for each and all criteria. To measure the influence of varus deformity on gap width difference, three subgroups were formed based on the deformity. Data were analyzed at 0°, 30°, 60° and 90° flexion. The effect of patient factors (gender, BMI, age) on gap sizes was tested by performing subgroup analyses. RESULTS Only 444 of 680 (65%) patients met all three varus knee criteria. The lateral extension gap (4.1 mm) was significantly larger than the medial extension gap (0.6 mm) in 657 (97%) patients and the gap difference highly correlated with the amount of varus deformity (r2 = 0.62). In all flexion positions, however, no correlation between gap differences and varus deformity existed. Women had significantly larger extension and flexion gaps. Age and BMI showed no significant effect on gap widths. CONCLUSION Varus knees show a large inter-individual variability regarding gap widths and gap differences. The amount of varus deformity correlates highly with the medio-lateral gap difference in extension, but not in any flexion angle. As varus knees are not all alike, a uniform surgical technique will not treat all varus knees adequately and the individual gap sizes need to be analyzed and addressed accordingly with an individualized balancing technique. Which final balancing goal should be achieved needs to be analyzed in future studies. LEVEL OF EVIDENCE Level III.
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Song SJ, Lee HW, Bae DK, Park CH. Mid-flexion laxity could be identified with continuous flexion-arc gap assessment in patients with a large preoperative convergence angle. Knee Surg Sports Traumatol Arthrosc 2022; 31:1307-1315. [PMID: 35048142 DOI: 10.1007/s00167-021-06846-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 12/07/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE To analyze the incidence of intraoperative mid-flexion laxity using continuous flexion-arc gap assessment, risk factors for mid-flexion laxity, and clinical results in navigation-assisted total knee arthroplasty (TKA). METHODS Ninety posterior-stabilized TKAs were performed under navigation guidance for patients with degenerative arthritis and varus deformity. Intraoperatively, the gap between the trial femoral component and insert was evaluated in the navigation system with continuous flexion-arc gap assessment. Each medial and lateral gap at flexion (90°) and extension (0°) were made to be less than 3 mm. Mid-flexion laxity was determined when the gap in the flexion range between 15° and 60° was 3 mm or more. The proportion of knees with mid-flexion laxity was investigated. The factors affecting mid-flexion laxity were identified in terms of demographics, preoperative convergence angle, and change in joint line height and posterior femoral offset. The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated. RESULTS There were 31 cases (34.4%) of lateral mid-flexion laxity (average peak mid-flexion gap = 3.7 mm). The other 59 cases did not show mid-flexion laxity. The preoperative convergence angle was the only significant factor affecting lateral mid-flexion laxity (odds ratio = 1.466, p = 0.002). There were no significant differences in the clinical results between the groups with and without mid-flexion laxity. CONCLUSIONS The continuous flexion-arc gap assessment was useful in evaluating mid-flexion laxity using navigation-assisted TKA. The preoperative convergence angle, reflecting soft-tissue laxity, can be a practical and simple radiographic finding for predicting lateral mid-flexion laxity. LEVEL OF EVIDENCE IV.
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Affiliation(s)
- Sang Jun Song
- Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 130-872, Korea
| | - Hyun Woo Lee
- Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 130-872, Korea
| | - Dae Kyung Bae
- Department of Orthopaedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Korea
| | - Cheol Hee Park
- Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 130-872, Korea.
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Song SJ, Lee HW, Park CH. Intraoperative Assessment of Gap Balancing in Total Knee Arthroplasty Using Navigation with Joint Stability Graphs. J Knee Surg 2021; 36:540-547. [PMID: 34794197 DOI: 10.1055/s-0041-1739200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The purpose of this study was to assess continuous gaps in the replaced knee throughout the full range of motion (ROM) after total knee arthroplasty (TKA) using a joint stability graph, and to analyze the gap laxity in the mid-flexion range. Ninety-three TKAs were performed using imageless navigation with a joint stability graph. While positioning guides for each respective cut, the surgeon can safely preview the resection's impact for the resulting joint gaps and control the soft tissue balance at the knee flexion of 0° (extension) and 90° (flexion). The gaps between the femoral component and insert were evaluated throughout the full ROM using the joint stability graph. The mechanical axis (MA) and change of joint line height were radiographically evaluated. Posthoc power analyses using a significant α value of 0.05 were performed on the proportion of the mid-flexion instability as a primary outcome to determine whether the sample had sufficient power. The power was determined to be sufficient (100%). The flexion-extension gap differences in each medial and lateral compartment and the mediolateral gap differences in flexion and extension were all ≤3 mm. None of the knees had mid-flexion instability, which is defined by a peak mid-flexion gap that is 3 mm greater than the smaller value of flexion or extension gap. The average MA was well corrected from varus 11.4° to varus 1.0° postoperatively. The proportion of postoperative well-aligned knees (MA ≤ 3°) was 87.1%. The joint line height was well preserved (14.7 vs. 14.8 mm, p = 0.751). The joint stability graph in TKA using the navigation can effectively evaluate the continuous gap throughout the ROM, including the mid-flexion range. Mid-flexion instability was uncommon in primary TKAs with appropriate alignment and proper preservation of the joint line. The Level of evidence for the study is IV.
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Affiliation(s)
- Sang Jun Song
- Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Hyun Woo Lee
- Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Cheol Hee Park
- Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Korea
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Instability, an unforeseen diagnosis of the Legion™ hinge knee system. Knee 2021; 28:97-103. [PMID: 33321414 DOI: 10.1016/j.knee.2020.11.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 10/12/2020] [Accepted: 11/16/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND Instability is an infrequently encountered diagnosis in rotating hinge knee (rHK) implants. With the introduction of a new rHK implant, we encountered multiple patients who complained of instability. This article presents its prevalence while describing our diagnostic and treatment algorithms. METHODS A retrospective analysis of a cohort of all consecutive patients treated with the Legion™ Hinge Knee System (Smith&Nephew, Memphis, Tennessee) as primary or revision procedure between July 2014 and December 2018 was performed. All patients reporting a sense of instability or having recurrent joint effusion after activity were suspected of experiencing instability. Stress X-rays were performed and brace treatment was started. In patients with insufficient effect of brace treatment, a liner exchange to a thicker liner was performed. Prevalence of instability and the effect of treatment was analysed descriptively. RESULTS In total, six patients were categorized as patients having instability problems (prevalence 3.5%; male:female ratio 5:1; median age 69.5 years; all revision procedures). Indication for revision to the Legion rHK implant was infection (three), instability (two) and aseptic loosening (one). In two patients, a prior rHK implant was revised. All patients showed tilting beyond the tolerance on stress X-ray examination. Brace treatment was adequate in three patients; in the other three patients a liner exchange was performed, two of which were satisfied. CONCLUSION Instability is an infrequently encountered diagnosis in rHK implants. The design of the Legion rHK implant seems prone to this problem with a prevalence of 3.5%. If brace treatment is insufficient a liner exchange might be considered.
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