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Ex vivo estimation of cementless femoral stem stability using an instrumented hammer. Clin Biomech (Bristol, Avon) 2020; 76:105006. [PMID: 32388077 DOI: 10.1016/j.clinbiomech.2020.105006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND The success of cementless hip arthroplasty depends on the primary stability of the femoral stem. It remains difficult to assess the optimal number of impacts to guarantee the femoral stem stability while avoiding bone fracture. The aim of this study is to validate a method using a hammer instrumented with a force sensor to monitor the insertion of femoral stem in bovine femoral samples. METHODS Different cementless femoral stem were impacted into five bovine femur samples, leading to 99 configurations. Three methods were used to quantify the insertion endpoint: the impact hammer, video motion tracking and the surgeon proprioception. For each configuration, the number of impacts performed by the surgeon until he felt a correct insertion was noted Nsurg. The insertion depth E was measured through video motion tracking, and the impact number Nvid corresponding to the end of the insertion was estimated. Two indicators, noted I and D, were determined from the analysis of the time variation of the force, and the impact number Nd corresponding to a threshold reached in D variation was estimated. FINDINGS The pullout force of the femoral stem was significantly correlated with I (R2 = 0.81). The values of Nsurg, Nvid and Nd were similar for all configurations. INTERPRETATION The results validate the use of the impact hammer to assess the primary stability of the femoral stem and the moment when the surgeon should stop the impaction procedure for an optimal insertion, which could lead to the development of a decision support system.
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2
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Chanda S, Mukherjee K, Gupta S, Pratihar DK. A comparative assessment of two designs of hip stem using rule-based simulation of combined osseointegration and remodelling. Proc Inst Mech Eng H 2019; 234:118-128. [DOI: 10.1177/0954411919890998] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The stem–bone interface of cementless total hip arthroplasty undergoes an adaptive process of bone ingrowth until the two parts become osseointegrated. Another important phenomenon associated with aseptic loosening of hip stem is stress-shielding induced adverse bone remodelling. The objective of this study was to preclinically assess the relative performances of two distinct designs of hip stems by addressing the combined effect of bone remodelling and osseointegration, based on certain rule-based criteria obtained from the literature. Premised upon non-linear finite element analyses of patient-specific implanted femur models, the study attempts to ascertain in silico outcome of the hip stem designs based on an evolutionary interfacial condition, and to further comment on the efficacy of the rule-based technique on the prediction of peri-prosthetic osseointegration. One of the two hip stem models was a trade-off design obtained from an earlier shape optimization study, and the other was based on TriLock stem (DePuy). Both designs predicted similar long-term osseointegration (∼89% surface), although trade-off stem predicted higher post-operative osseointegration. Proximal bone resorption was found higher for TriLock (by ∼110%) as compared to trade-off model. The rule-based technique predicted clinically coherent osseointegration around both stems and appears to be an alternative to expensive mechanobiology-based schemes.
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Affiliation(s)
- Souptick Chanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - Kaushik Mukherjee
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Sanjay Gupta
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Dilip Kumar Pratihar
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
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3
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Modal frequency and shape curvature as a measure of implant fixation: A computer study on the acetabular cup. Med Eng Phys 2018; 60:30-38. [DOI: 10.1016/j.medengphy.2018.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 06/24/2018] [Accepted: 07/15/2018] [Indexed: 11/18/2022]
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4
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Impact Force, Polar Gap and Modal Parameters Predict Acetabular Cup Fixation: A Study on a Composite Bone. Ann Biomed Eng 2018; 46:590-604. [DOI: 10.1007/s10439-018-1980-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 01/06/2018] [Indexed: 10/18/2022]
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Tijou A, Rosi G, Hernigou P, Flouzat-Lachaniette CH, Haïat G. Ex Vivo Evaluation of Cementless Acetabular Cup Stability Using Impact Analyses with a Hammer Instrumented with Strain Sensors. SENSORS 2017; 18:s18010062. [PMID: 29280982 PMCID: PMC5796378 DOI: 10.3390/s18010062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/14/2017] [Accepted: 12/23/2017] [Indexed: 11/16/2022]
Abstract
The acetabular cup (AC) implant stability is determinant for the success of cementless hip arthroplasty. A method based on the analysis of the impact force applied during the press-fit insertion of the AC implant using a hammer instrumented with a force sensor was developed to assess the AC implant stability. The aim of the present study was to investigate the performance of a method using a hammer equipped with strain sensors to retrieve the AC implant stability. Different AC implants were inserted in five bovine samples with different stability conditions leading to 57 configurations. The AC implant was impacted 16 times by the two hammers consecutively. For each impact; an indicator IS (respectively IF) determined by analyzing the time variation of the signal corresponding to the averaged strain (respectively force) obtained with the stress (respectively strain) hammer was calculated. The pull-out force F was measured for each configuration. F was significantly correlated with IS (R² = 0.79) and IF (R² = 0.80). The present method has the advantage of not modifying the shape of the hammer that can be sterilized easily. This study opens new paths towards the development of a decision support system to assess the AC implant stability.
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Affiliation(s)
- Antoine Tijou
- Laboratoire de Modélisation et de Simulation Multi-Echelle, CNRS, UMR CNRS 8208, 61 Avenue du Général de Gaulle, 94010 Créteil, France;
| | - Giuseppe Rosi
- Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208, Université Paris-Est, 61 Avenue du Général de Gaulle, 94010 Créteil, France;
| | - Philippe Hernigou
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Henri Mondor AP-HP, CHU Paris 12, Université Paris-Est, 51 Avenue du Maréchal de Lattre de Tassigny, 94010 Créteil, France; (P.H.); (C.-H.F.-L.)
- Équipe 10, Groupe 5, IMRB U955, INSERM/UPEC, 51 Avenue du Maréchal de Lattre de Tassigny, 94010 Créteil, France
| | - Charles-Henri Flouzat-Lachaniette
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Henri Mondor AP-HP, CHU Paris 12, Université Paris-Est, 51 Avenue du Maréchal de Lattre de Tassigny, 94010 Créteil, France; (P.H.); (C.-H.F.-L.)
- Équipe 10, Groupe 5, IMRB U955, INSERM/UPEC, 51 Avenue du Maréchal de Lattre de Tassigny, 94010 Créteil, France
| | - Guillaume Haïat
- Laboratoire de Modélisation et de Simulation Multi-Echelle, CNRS, UMR CNRS 8208, 61 Avenue du Général de Gaulle, 94010 Créteil, France;
- Correspondence: ; Tel.: +33-1-45-17-14-31
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Leuridan S, Goossens Q, Vander Sloten T, De Landsheer K, Delport H, Pastrav L, Denis K, Desmet W, Vander Sloten J. Vibration-based fixation assessment of tibial knee implants: A combined in vitro and in silico feasibility study. Med Eng Phys 2017; 49:109-120. [DOI: 10.1016/j.medengphy.2017.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 07/07/2017] [Accepted: 08/13/2017] [Indexed: 10/18/2022]
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7
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Goossens Q, Leuridan S, Henyš P, Roosen J, Pastrav L, Mulier M, Desmet W, Denis K, Vander Sloten J. Development of an acoustic measurement protocol to monitor acetabular implant fixation in cementless total hip Arthroplasty: A preliminary study. Med Eng Phys 2017; 49:28-38. [PMID: 28760407 DOI: 10.1016/j.medengphy.2017.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 04/24/2017] [Accepted: 07/12/2017] [Indexed: 11/27/2022]
Abstract
In cementless total hip arthroplasty (THA), the initial stability is obtained by press-fitting the implant in the bone to allow osseointegration for a long term secondary stability. However, finding the insertion endpoint that corresponds to a proper initial stability is currently based on the tactile and auditory experiences of the orthopedic surgeon, which can be challenging. This study presents a novel real-time method based on acoustic signals to monitor the acetabular implant fixation in cementless total hip arthroplasty. Twelve acoustic in vitro experiments were performed on three types of bone models; a simple bone block model, an artificial pelvic model and a cadaveric model. A custom made beam was screwed onto the implant which functioned as a sound enhancer and insertor. At each insertion step an acoustic measurement was performed. A significant acoustic resonance frequency shift was observed during the insertion process for the different bone models; 250 Hz (35%, second bending mode) to 180 Hz (13%, fourth bending mode) for the artificial bone block models and 120 Hz (11%, eighth bending mode) for the artificial pelvis model. No significant frequency shift was observed during the cadaveric experiment due to a lack of implant fixation in this model. This novel diagnostic method shows the potential of using acoustic signals to monitor the implant seating during insertion.
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Affiliation(s)
- Quentin Goossens
- KU Leuven, Department of Mechanical Engineering, Smart Instrumentation, Andreas Vesaliusstraat 13, 3000 Leuven, Belgium.
| | - Steven Leuridan
- KU Leuven, Department of Mechanical Engineering, Biomechanics Section, Celestijnenlaan 300C, 3001 Leuven, Belgium
| | - Petr Henyš
- Technical University of Liberec, Studentská 1402/2,461 17 Liberec, Czech Republic
| | - Jorg Roosen
- KU Leuven, UZ Pellenberg, Department of Orthopaedics, Weligerveld 1, 3212 Pellenberg, Belgium
| | - Leonard Pastrav
- KU Leuven, Department of Mechanical Engineering, Smart Instrumentation, Andreas Vesaliusstraat 13, 3000 Leuven, Belgium
| | - Michiel Mulier
- KU Leuven, UZ Pellenberg, Department of Orthopaedics, Weligerveld 1, 3212 Pellenberg, Belgium
| | - Wim Desmet
- KU Leuven, Department of Mechanical Engineering, Production Engineering, Machine Design and Automation Division, Celestijnenlaan 300C, 3001 Leuven, Belgium
| | - Kathleen Denis
- KU Leuven, Department of Mechanical Engineering, Smart Instrumentation, Andreas Vesaliusstraat 13, 3000 Leuven, Belgium
| | - Jos Vander Sloten
- KU Leuven, Department of Mechanical Engineering, Biomechanics Section, Celestijnenlaan 300C, 3001 Leuven, Belgium
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Michel A, Bosc R, Sailhan F, Vayron R, Haiat G. Ex vivo estimation of cementless acetabular cup stability using an impact hammer. Med Eng Phys 2015; 38:80-6. [PMID: 26671784 DOI: 10.1016/j.medengphy.2015.10.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 08/17/2015] [Accepted: 10/15/2015] [Indexed: 11/29/2022]
Abstract
Obtaining primary stability of acetabular cup (AC) implants is one of the main objectives of press-fit procedures used for cementless hip arthroplasty. The aim of this study is to investigate whether the AC implant primary stability can be evaluated using the signals obtained with an impact hammer. A hammer equipped with a force sensor was used to impact the AC implant in 20 bovine bone samples. For each sample, different stability conditions were obtained by changing the cavity diameter. For each configuration, the inserted AC implant was impacted four times with a maximum force comprised between 2500 and 4500 N. An indicator I was determined based on the partial impulse estimation and the pull-out force was measured. The implant stability and the value of the indicator I reached a maximum value for an interference fit equal to 1 mm for 18 out of 20 samples. When pooling all samples and all configurations, the implant stability and I were significantly correlated (R(2) = 0.83). The AC implant primary stability can be assessed through the analysis of the impact force signals obtained using an impact hammer. Based on these ex vivo results, a medical device could be developed to provide a decision support system to the orthopedic surgeons.
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Affiliation(s)
- Adrien Michel
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208,61 Avenue du Général de Gaulle, Créteil 94010, France
| | - Romain Bosc
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Henri Mondor AP-HP, CHU Paris 12, Université Paris-Est, 51 avenue du Maréchal de Lattre de Tassigny, Créteil 94000, France
| | - Frédéric Sailhan
- Service de Chirurgie Ostéo-articulaire et carcinologique, Clinique Arago, 54, boulevard Saint-Jacques, 75014 Paris, France
| | - Romain Vayron
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208,61 Avenue du Général de Gaulle, Créteil 94010, France
| | - Guillaume Haiat
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208,61 Avenue du Général de Gaulle, Créteil 94010, France; Ecole de Technologie Superieure, Department of Mechanical Engineering, 1100 Rue Notre-Dame Ouest, Montréal, QC H3C 1K3, Canada.
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Abstract
Femoral neck preserving stems have been developed to take advantage of the biomechanical properties of the femoral neck, and to optimise femoral anchorage and load distribution. The aim of this study was to report the clinical and radiological results in a group of 126 patients (150 hips), operated on for a total hip arthroplasty with the CFP stem. Clinical evaluation considered Harris Hip Score (HHS), thigh pain, Charnley classification, peri- and post-operative complications. Radiographic variables were stem sizing and alignment, femoral and acetabular osteolysis, the quality of cementation and restoration of the offset. The HHS at mean follow-up of 66 months was 83 points. We did not observe femoral or acetabular osteolysis, secondary malalignment or radiographic reactions, but only bone remodelling under the collar. The CFP stem must be used appropriately based on pre-operative planning (correct morphology and torsion of the femur). The surgical technique is straightforward if carried out step by step. We did not see any cases of significant limb length discrepancy.
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10
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Michel A, Bosc R, Mathieu V, Hernigou P, Haiat G. Monitoring the press-fit insertion of an acetabular cup by impact measurements: influence of bone abrasion. Proc Inst Mech Eng H 2014; 228:1027-34. [PMID: 25258009 DOI: 10.1177/0954411914552433] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Press-fit procedures used for the insertion of cementless hip prostheses aim at obtaining optimal implant primary stability. We have previously used the measurement of impact duration to follow the insertion of the acetabular cup implant within bone tissue. The aim of this study was to investigate the variation of the value of the impact momentum due to successive insertions of the acetabular cup into bone tissue. The results obtained with impact momentum and contact duration measurements were compared. A total of 10 bovine bone samples were subjected to three successive procedures consisting of 10 reproducible impacts (3.5 kg falling 40 mm). Each procedure aimed at inserting the acetabular cup implant into the same bone cavity. The time variation of force during each impact was recorded by a force sensor, allowing the measurement of the impact duration (I 1) and momentum (I 2). The value of I 2 increased as a function of the impact number and reached a constant value after N 2 = 5.07 ± 1.31 impacts. Moreover, statistical analyses show that N 2 decreased significantly as a function of the number of experiments, which may be due to abrasion phenomena at the bone-implant interface. Abrasion phenomena led to a faster insertion of the acetabular cup when the implant had been previously inserted into the same bone cavity. An empirical analytical model considering a flat punch configuration to model the bone-implant contact conditions was used to understand the trend of the variation of I 2 during the insertion of the acetabular cup. The measurement of the force during impacts is useful to assess the bone-implant interface properties, but needs to be validated in the clinic to be useful for orthopaedic surgeons intra-operatively.
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Affiliation(s)
- Adrien Michel
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle - UMR CNR 8208, Créteil, France
| | - Romain Bosc
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle - UMR CNR 8208, Créteil, France
| | - Vincent Mathieu
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle - UMR CNR 8208, Créteil, France
| | - Philippe Hernigou
- Service de Chirurgie Orthopédique et Traumatologique, Hôpital Henri Mondor AP-HP, CHU Paris 12, Université Paris-Est, France
| | - Guillaume Haiat
- CNRS, Laboratoire de Modélisation et de Simulation Multi-Echelle - UMR CNR 8208, Créteil, France
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Ruther C, Nierath H, Ewald H, Cunningham JL, Mittelmeier W, Bader R, Kluess D. Investigation of an acoustic-mechanical method to detect implant loosening. Med Eng Phys 2013; 35:1669-75. [PMID: 23860369 DOI: 10.1016/j.medengphy.2013.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 06/04/2013] [Accepted: 06/23/2013] [Indexed: 10/26/2022]
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12
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Ruther C, Schulze C, Boehme A, Nierath H, Ewald H, Mittelmeier W, Bader R, Kluess D. Investigation of a passive sensor array for diagnosis of loosening of endoprosthetic implants. SENSORS 2012; 13:1-20. [PMID: 23344370 PMCID: PMC3574661 DOI: 10.3390/s130100001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 12/05/2012] [Accepted: 12/13/2012] [Indexed: 11/27/2022]
Abstract
Currently, imaging methods are used to diagnose loosening of endoprosthetic implants, but fail to achieve 100% accuracy. In this study, a passive sensor array which is based on the interaction between magnetic oscillators inside the implant and an excitation coil outside the patient was investigated. The excited oscillators produce sound in the audible range, which varies according to the extent of loosening. By performing several experimental tests, the sensor array was optimized to guarantee reproducible and selective excitation of the sound emission. Variation in the distance between the oscillators demonstrated a definite influence on the quality of the generated sound signal. Furthermore, a numerical design analysis using the boundary element method was generated for consideration of the magnetic field and the selectivity of the oscillators during excitation. The numerical simulation of the coil showed the higher selectivity of a coil with a C-shape compared to a cylindrical coil. Based on these investigations, the passive sensor system reveals the potential for detection of implant loosening. Future aims include the further miniaturization of the oscillators and measurements to determine the sensitivity of the proposed sensor system.
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Affiliation(s)
- Cathérine Ruther
- Department of Orthopaedics, University Medicine Rostock, Doberaner Str. 142, 18057 Rostock, Germany; E-Mails: (C.S.); (A.B.); (W.M.); (R.B.); (D.K.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-381-4949-375; Fax: +49-381-4949-308
| | - Christian Schulze
- Department of Orthopaedics, University Medicine Rostock, Doberaner Str. 142, 18057 Rostock, Germany; E-Mails: (C.S.); (A.B.); (W.M.); (R.B.); (D.K.)
| | - Andrea Boehme
- Department of Orthopaedics, University Medicine Rostock, Doberaner Str. 142, 18057 Rostock, Germany; E-Mails: (C.S.); (A.B.); (W.M.); (R.B.); (D.K.)
| | - Hannes Nierath
- Institute of General Electrical Engineering, University of Rostock, Albert-Einstein-Str. 2, 18055 Rostock, Germany; E-Mails: (H.N.); (H.E.)
| | - Hartmut Ewald
- Institute of General Electrical Engineering, University of Rostock, Albert-Einstein-Str. 2, 18055 Rostock, Germany; E-Mails: (H.N.); (H.E.)
| | - Wolfram Mittelmeier
- Department of Orthopaedics, University Medicine Rostock, Doberaner Str. 142, 18057 Rostock, Germany; E-Mails: (C.S.); (A.B.); (W.M.); (R.B.); (D.K.)
| | - Rainer Bader
- Department of Orthopaedics, University Medicine Rostock, Doberaner Str. 142, 18057 Rostock, Germany; E-Mails: (C.S.); (A.B.); (W.M.); (R.B.); (D.K.)
| | - Daniel Kluess
- Department of Orthopaedics, University Medicine Rostock, Doberaner Str. 142, 18057 Rostock, Germany; E-Mails: (C.S.); (A.B.); (W.M.); (R.B.); (D.K.)
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Ruther C, Ewald H, Mittelmeier W, Fritsche A, Bader R, Kluess D. A Novel Sensor Concept for Optimization of Loosening Diagnostics in Total Hip Replacement. J Biomech Eng 2011; 133:104503. [DOI: 10.1115/1.4005222] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The main reason for the revision of total hip replacements is aseptic loosening, caused by stress shielding and wear particle induced osteolysis. In order to detect an implant loosening early, the osseointegration of endoprosthetic implants must be measured exactly. Currently applied diagnostic methods, such as standard radiographs and clinical symptomatology, often result in an imprecise diagnosis. A novel radiation-free method to improve the diagnostic investigation of implant loosening is presented. The osseointegration of an implant can be identified using mechanical magnetic sensors (oscillators), which impinge on small membranes inside an implant component, e.g., the femoral hip stem. The maximum velocity after impingement of the oscillator depends on the osseointegration of the implant. Excitation of the oscillator is realized by a coil outside the human body. Another external coil is used to detect the velocity of the oscillator. To demonstrate the principle of the novel loosening sensor, an overdimensioned test device was designed to measure simulated loosening phases in the first experimental tests with different material layers. The overdimensioned test device of the loosening sensor showed significant differences in the various phases of fixation. Analysis of the membrane without any material layer in the case of advanced loosening resulted in a 23% higher maximum velocity compared to an attached artificial bone layer. Based on these preliminary results, the sensor system shows potential for the detection of implant loosening. Moreover, the proposed system could be used in experimental applications to determine the quality of bioactive coatings and new implant materials.
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Affiliation(s)
- Cathérine Ruther
- Department of Orthopedics, University of Rostock, 18057 Rostock, Germany
| | - Hartmut Ewald
- Institute of General Electrical Engineering, University of Rostock, 18057 Rostock, Germany
| | | | - Andreas Fritsche
- Department of Orthopedics, University of Rostock, 18057 Rostock, Germany
| | - Rainer Bader
- Department of Orthopedics, University of Rostock, 18057 Rostock, Germany
| | - Daniel Kluess
- Department of Orthopedics, University of Rostock, 18057 Rostock, Germany
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Reggiani B, Cristofolini L, Taddei F, Viceconti M. Sensitivity of the Primary Stability of a Cementless Hip Stem to Its Position and Orientation. Artif Organs 2008; 32:555-60. [DOI: 10.1111/j.1525-1594.2008.00577.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Varini E, Cristofolini L, Traina F, Viceconti M, Toni A. Can the rasp be used to predict intra-operatively the primary stability that can be achieved by press-fitting the stem in cementless hip arthroplasty? Clin Biomech (Bristol, Avon) 2008; 23:408-14. [PMID: 18068878 DOI: 10.1016/j.clinbiomech.2007.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 09/25/2007] [Accepted: 11/02/2007] [Indexed: 02/07/2023]
Abstract
BACKGROUND Success of cementless hip stems implantation depends mainly on primary stability which, in turn, depends on the degree of press-fitting achieved, and optimal medullary canal filling by the selected stem size. Stem size, based on templating and pre-operative planning software, only partially avoids stem mis-sizing. Mis-sizing can produce implant instability and/or wasting the wrong-sized stem. METHODS An intra-operative device was designed that enabled real-time measurement of rasp-bone micromotions by applying torque manually. Rasp stability was assessed in vitro in seven femurs after femoral canal preparation when the rasp was fully seated. Then, primary implant stability was assessed with the stem press-fitted in the position indicated as optimal by the surgeon. Torque-micromotion curves were compared for the rasp and the stem. Finally, the protocol was applied to two hip patients. FINDINGS Rasp stability micromotions were successfully measured in all in vitro specimens and all patients. The slope of the initial part of the rasp torque-micromotion curve was correlated with the slope of the stem curve (correlation coefficient=0.798, P-value=0.001). The entire procedure for measuring rasp stability added less than two minutes to the 75-80-min operating time. INTERPRETATION This study indicates that the rasp stability can be used to predict the maximal primary stability that can eventually be achieved by the selected stem size. Early prediction of stem stability enables correcting the stem size, if necessary, before the press-fitting procedure is initiated, thus saving operating time and the cost of a new stem.
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Affiliation(s)
- Elena Varini
- Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
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Lannocca M, Varini E, Cappello A, Cristofolini L, Bialoblocka E. Intra-operative evaluation of cementless hip implant stability: A prototype device based on vibration analysis. Med Eng Phys 2007; 29:886-94. [PMID: 17101289 DOI: 10.1016/j.medengphy.2006.09.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 09/19/2006] [Accepted: 09/24/2006] [Indexed: 10/23/2022]
Abstract
Cementless implants are mechanically stabilized during surgery by a press-fitting procedure. Good initial stability is crucial to avoid stem loosening and bone cracking, therefore, the surgeon must achieve optimal press-fitting. A possible approach to solve this problem and assist the surgeon in achieving the optimal compromise, involves the use of vibration analysis. The present study aimed to design and test a prototype device able to evaluate the primary mechanical stability of a cementless prosthesis, based on vibration analysis. In particular, the goal was to discriminate between stable and quasi-stable implants; thus the stem-bone system was assumed to be linear in both cases. For that reason, it was decided to study the frequency responses of the system, instead of the harmonic distortion. The prototype developed consists of a piezoelectric exciter connected to the stem and an accelerometer attached to the femur. Preliminary tests were performed on four composite femurs implanted with a conventional stem. The results showed that the input signal was repeatable and the output could be recorded accurately. The most sensitive parameter to stability was the shift in resonance frequency of the stem-bone system, which was highly correlated with residual micromotion on all four specimens.
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Affiliation(s)
- Maurizio Lannocca
- University of Bologna, Engineering Faculty, DEIS, Viale Risorgimento 2, 40136 Bologna, Italy.
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Reggiani B, Cristofolini L, Varini E, Viceconti M. Predicting the subject-specific primary stability of cementless implants during pre-operative planning: Preliminary validation of subject-specific finite-element models. J Biomech 2007; 40:2552-8. [PMID: 17229427 DOI: 10.1016/j.jbiomech.2006.10.042] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 10/30/2006] [Indexed: 11/18/2022]
Abstract
Pre-operative planning help the surgeon in taking the proper clinical decision. The ultimate goal of this work is to develop numerical models that allow the surgeon to estimate the primary stability during the pre-operative planning session. The present study was aimed to validate finite-element (FE) models accounting for patient and prosthetic size and position as planned by the surgeon. For this purpose, the FE model of a cadaveric femur was generated starting from the CT scan and the anatomical position of a cementless stem derived by a skilled surgeon using a pre-operative CT-based planning simulation software. In-vitro experimental measurements were used as benchmark problem to validate the bone-implant relative micromotions predicted by the patient-specific FE model. A maximum torque in internal rotation of 11.4 Nm was applied to the proximal part of the hip stem. The error on the maximum predicted micromotion was 12% of the peak micromotion measured experimentally. The average error over the entire range of applied torques was only 7% of peak measurement. Hence, the present study confirms that it is possible to accurately predict the level of primary stability achieved for cementless stems using numerical models that account for patient specificity and surgical variability.
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Affiliation(s)
- B Reggiani
- DIEM - Dipartimento di Ingegneria delle Costruzioni Meccaniche, Nucleari, Aeronautiche e di Metallurgia, Università degli Studi di Bologna, Viale Risorgimento 2, 40136, Bologna, Italy.
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18
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Varini E, Cristofolini L, Viceconti M, Traina F. Stem Damage During Implantation of Modular Hip Prostheses. Artif Organs 2006; 30:564-7. [PMID: 16836740 DOI: 10.1111/j.1525-1594.2006.00261.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modular hip prostheses are commonly used today. Dedicated surgical auxiliary instrumentation is indispensable. A correct coupling between the prosthesis and the instrument is necessary to avoid damage. Based on a specific commercial design (AnCAFit, Wright Cremascoli Ortho, Toulon, France), the aim of this work was to assess if stem holders of modular prostheses can induce any stem damage, and if so, to identify the features that provide minimal damage. Two different stem holder connector designs were investigated. The surface of the stem cavity was inspected to identify the damage caused by the use of the two connectors after a simulated surgical handling. Both connectors induced some damage, with significantly more damage being caused by a supposedly improved design. Scars due to contact with the stem holder were observed on the stem cavity surface. This may be sufficient to trigger increased fretting damage during service life, causing the production of fretting debris.
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Affiliation(s)
- Elena Varini
- Dipartimento di Elettronica, Informatica e Sistemistica, University of Bologna, Bologna, Italy
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