Total hip arthroplasty has a very high success rate, as measured by pain relief, improved functio... more Total hip arthroplasty has a very high success rate, as measured by pain relief, improved function and patient satisfaction. However, on occasion, complications do happen. This paper will review three cases that required surgical intervention and design features of a modular stem making revision surgery considerably easier. Three patients received cementless THA within the past two years. All three had a 'Dual Press™' proximal modular stem design. Two patients had metal-on-metal (MOM) bearings that shifted position and one had a cementless porous cup with a 36 mm poly bearing with metal head that dislocated. All were performed at the same hospital by the senior author using a small posterior surgical approach. All three required revision surgery that was made considerably easier by the design feature of proximal Dual Pressâ modularity.
Artificial disc replacement was performed in six patients with an average age of 55 years and ave... more Artificial disc replacement was performed in six patients with an average age of 55 years and average follow-up of 3.4 years. Four of the six patients had juxtafusion degeneration, one had multilevel disc degeneration, and one patient had isolated disc resorption. The Acroflex disc (Acromed Corporation, Cleveland, OH), which was used in the replacement, is composed of a rubber core vulcanized to two titanium end plates. The latter have superior posts to provide for initial mechanical fixation and porous in-growth surfaces for long-term fixation. Satisfactory results occurred in four of six patients. Poor results occurred in the presence of deformity that resulted in prosthetic failure and isolated disc resorption. There was an average 8 degrees angular and 2.3-mm translational movement and satisfactory in-growth at all interfaces. Design objectives of endurance, biocompatibility, geometry, kinematics, constraint, dynamics, stability, and fail-safe were met; however, this study is preliminary in nature.
Introduction The use of short stems has been growing in THA for the past five years. As a result,... more Introduction The use of short stems has been growing in THA for the past five years. As a result, a large number of short stem designs are available in the market place. However, fixation points differ for many of the designs resulting in different radiographic modeling creating confusion when trying to collate to clinical findings. We have created a classification system in an attempted to provide clarity in analyzing radiographic and clinical findings. Method Femoral implants described as “short stems” were evaluated. The range of lengths for stem type and the method of achieving initial implant stability was determined. The optimal radiographic position of each of these implants and type of bone remodeling associated with this placement was evaluated. Stems were defined as “short” if the tip reached or was proximal to the metaphyseal-diaphyseal junction. This location on the proximal femur was defined as the place at which the medial-lateral metaphyseal flare became parallel. Stems were then classified as: 1.) Metaphyseal Stabilized; 2.) Neck Stabilized; 3.) Head Stabilized. An analysis of radiographic with a minimum of one year follow up were reviewed and posted as to the classification system Results The range of stem lengths for stem type and the method of achieving initial implant stability was determined. A classification of short-stemmed components has been defined, making it possible to evaluate and differentiate both radiographic and clinical findings. Not all so-called short stems exhibit the same radiographic and clinical findings. It also became apparent that the different stabilization points require specific surgical techniques to ensure reproducible good results. Findings for neck stabilized present with different findings as compared to metaphyseal stabilized and head stabilized. We are optimistic that this classification system will help to compare short-stemmed implants and how they performed to the more traditional convention cementless stems.
Bone Joint Journal Orthopaedic Proceedings Supplement, Mar 1, 2013
Introduction Architectural changes occurring in the proximal femur after THA continues to be a pr... more Introduction Architectural changes occurring in the proximal femur after THA continues to be a problem. Stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and breakage of the implant. A new novel tissue sparing neck-stabilised stem has been designed to address these concerns. Methods Over 1,200 stems have been implanted since April 2010 and 2012. Patient profile showed two-thirds being female with an age range between 17 to early 90s. 90% were treated for OA. This stem has been used in all Dorr bone classification (A, B, & C). Two surgical approaches were utilised (single anterior incision and standard posterior incision). All were used with a variety of cementless acetabular components and a variety of bearing surfaces (CoC, CoP, MoM, MoP). Complications were track by surgeon Members of the Tissue Sparing Study Group of the Joint Implant Surgery and Research Foundation. Complications include first year of limited clinical release. No surgeon was permitted usage without specific cadaver / surgical training. No head diameters below 32 mm were used. Observations There is a short but definitive learning curve (2–3 cases) and an easy transition for the O.R. team due to the limited inventory of stem sizes. The three main surgical technique features are: Level of neck resection, angle of resection and rasping the proximal medial curvature of the femur. Stem usage: size 0, 1 and 2 were used for more females and 3, 4, and 5 stems for males. The neutral modular neck was the single most selected (35%), however, all angled necks totaled 65% usage. Slightly more complications in the anterior approach compared to posterior approach. We are encouraged with our initial clinical / surgical / radiographic observations and believe our results warrant not only further evaluation but expanded evaluation of this tissue conserving approach to THA.
The emergence of modularity in total hip arthroplasty (THA) in the 1980s and 1990s was based on t... more The emergence of modularity in total hip arthroplasty (THA) in the 1980s and 1990s was based on the fact that the benefit of these design features outweighed the risk. The use of metallic modular junctions presents a unique set of advantages and problems for use in THA. The advantages include improvement in fit and fill of the implant to bone, restoration of joint mechanics, reduced complications in revision surgery and reduction of costly inventory. However, the risks or concerns are a little harder to identify and deal with. Certainly corrosion, and fatigue failure are the two most prevalent concerns but now the specifics of fretting wear and corrosive wear increasing particulate debris and the potential biological response is having an impact on the design and potential longevity of the reconstructed hip. Material and designs are facing a shorter life expectancy than what was previously thought, mostly due to an increasing level of physical activity by the patient. Because there ...
FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certa... more FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certain conventional cementless stems. 1 Yr. follow up demonstrates positive bone remodeling filling in calcar gap with this short curved proximal conical neck sparing stem. Introduction: Architectural changes occurring in the proximal femur after THA continues to be a problem. Proximal stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and or breakage of the implant. We are seeing younger patients with higher levels of physical activity as compared to just a decade ago. A tissue sparing total hip stem provides for less tissue damage, a quicker rehab and leaves behind more infrastructure in case of future revision surgery. Patients today demand more out of the hip reconstruction and their increase activity places a higher demand on the implant. A number of the current short stems introduced into the market are no more than standard ste...
FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certa... more FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certain conventional cementless stems. 1 Yr. follow up demonstrates positive bone remodeling filling in calcar gap with this short curved proximal conical neck sparing stem. Introduction: Architectural changes occurring in the proximal femur after THA continues to be a problem. Proximal stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and or breakage of the implant. We are seeing younger patients with higher levels of physical activity as compared to just a decade ago. A tissue sparing total hip stem provides for less tissue damage, a quicker rehab and leaves behind more infrastructure in case of future revision surgery. Patients today demand more out of the hip reconstruction and their increase activity places a higher demand on the implant. A number of the current short stems introduced into the market are no more than standard ste...
Purpose. To evaluate early and mid-term risk factors and dislocation rates in the posterior surgi... more Purpose. To evaluate early and mid-term risk factors and dislocation rates in the posterior surgical approach in three separate community private practices using a short curved neck-sparing total hip stem design.Material and Methods.The three senior authors performed 338 short curved neck-sparing stem designs since April 2010 to June 2014. Various cementless acetabular components were used for all three surgical centers based on preoperative and intraoperative risk factors. All cases were reviewed retrospectively for incidence of dislocation after surgery.Version and inclination of the acetabular component and version of the femoral component were assed intra-operatively prior to final implantation. Various risk factors were reviewed including surgical approach, cup position, combined cup and stem positioning, and femoral head size.There have been significant papers in the past ten years that have recommended large head diameters to reduce the chances of head/neck mechanical imping...
The aim of this paper is to review the influx of short stems for total hip arthroplasty. Not all ... more The aim of this paper is to review the influx of short stems for total hip arthroplasty. Not all short stems are created equal concerning fixation points for implant stability and length of engagement of the device in the proximal femur. Some devices are stabilized in the head, neck, metaphysis and metaphysis/diaphysis. Depending on stabilization and engagement area different short stems can have different indications, contraindications and clinical outcomes. As a result of our findings JISRF developed a classification system based on implant stabilization point and overall stem length.Keywords: short stems, head stabilized, neck stabilized, metaphyseal stabilized, metaphyseal diaphyseal stabilized
Board-certified orthopedic surgeon specializing in total hip and knee arthroplasty currently prac... more Board-certified orthopedic surgeon specializing in total hip and knee arthroplasty currently practicing in Oklahoma City, OK.
Total hip arthroplasty has a very high success rate, as measured by pain relief, improved functio... more Total hip arthroplasty has a very high success rate, as measured by pain relief, improved function and patient satisfaction. However, on occasion, complications do happen. This paper will review three cases that required surgical intervention and design features of a modular stem making revision surgery considerably easier. Three patients received cementless THA within the past two years. All three had a 'Dual Press™' proximal modular stem design. Two patients had metal-on-metal (MOM) bearings that shifted position and one had a cementless porous cup with a 36 mm poly bearing with metal head that dislocated. All were performed at the same hospital by the senior author using a small posterior surgical approach. All three required revision surgery that was made considerably easier by the design feature of proximal Dual Pressâ modularity.
Artificial disc replacement was performed in six patients with an average age of 55 years and ave... more Artificial disc replacement was performed in six patients with an average age of 55 years and average follow-up of 3.4 years. Four of the six patients had juxtafusion degeneration, one had multilevel disc degeneration, and one patient had isolated disc resorption. The Acroflex disc (Acromed Corporation, Cleveland, OH), which was used in the replacement, is composed of a rubber core vulcanized to two titanium end plates. The latter have superior posts to provide for initial mechanical fixation and porous in-growth surfaces for long-term fixation. Satisfactory results occurred in four of six patients. Poor results occurred in the presence of deformity that resulted in prosthetic failure and isolated disc resorption. There was an average 8 degrees angular and 2.3-mm translational movement and satisfactory in-growth at all interfaces. Design objectives of endurance, biocompatibility, geometry, kinematics, constraint, dynamics, stability, and fail-safe were met; however, this study is preliminary in nature.
Introduction The use of short stems has been growing in THA for the past five years. As a result,... more Introduction The use of short stems has been growing in THA for the past five years. As a result, a large number of short stem designs are available in the market place. However, fixation points differ for many of the designs resulting in different radiographic modeling creating confusion when trying to collate to clinical findings. We have created a classification system in an attempted to provide clarity in analyzing radiographic and clinical findings. Method Femoral implants described as “short stems” were evaluated. The range of lengths for stem type and the method of achieving initial implant stability was determined. The optimal radiographic position of each of these implants and type of bone remodeling associated with this placement was evaluated. Stems were defined as “short” if the tip reached or was proximal to the metaphyseal-diaphyseal junction. This location on the proximal femur was defined as the place at which the medial-lateral metaphyseal flare became parallel. Stems were then classified as: 1.) Metaphyseal Stabilized; 2.) Neck Stabilized; 3.) Head Stabilized. An analysis of radiographic with a minimum of one year follow up were reviewed and posted as to the classification system Results The range of stem lengths for stem type and the method of achieving initial implant stability was determined. A classification of short-stemmed components has been defined, making it possible to evaluate and differentiate both radiographic and clinical findings. Not all so-called short stems exhibit the same radiographic and clinical findings. It also became apparent that the different stabilization points require specific surgical techniques to ensure reproducible good results. Findings for neck stabilized present with different findings as compared to metaphyseal stabilized and head stabilized. We are optimistic that this classification system will help to compare short-stemmed implants and how they performed to the more traditional convention cementless stems.
Bone Joint Journal Orthopaedic Proceedings Supplement, Mar 1, 2013
Introduction Architectural changes occurring in the proximal femur after THA continues to be a pr... more Introduction Architectural changes occurring in the proximal femur after THA continues to be a problem. Stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and breakage of the implant. A new novel tissue sparing neck-stabilised stem has been designed to address these concerns. Methods Over 1,200 stems have been implanted since April 2010 and 2012. Patient profile showed two-thirds being female with an age range between 17 to early 90s. 90% were treated for OA. This stem has been used in all Dorr bone classification (A, B, & C). Two surgical approaches were utilised (single anterior incision and standard posterior incision). All were used with a variety of cementless acetabular components and a variety of bearing surfaces (CoC, CoP, MoM, MoP). Complications were track by surgeon Members of the Tissue Sparing Study Group of the Joint Implant Surgery and Research Foundation. Complications include first year of limited clinical release. No surgeon was permitted usage without specific cadaver / surgical training. No head diameters below 32 mm were used. Observations There is a short but definitive learning curve (2–3 cases) and an easy transition for the O.R. team due to the limited inventory of stem sizes. The three main surgical technique features are: Level of neck resection, angle of resection and rasping the proximal medial curvature of the femur. Stem usage: size 0, 1 and 2 were used for more females and 3, 4, and 5 stems for males. The neutral modular neck was the single most selected (35%), however, all angled necks totaled 65% usage. Slightly more complications in the anterior approach compared to posterior approach. We are encouraged with our initial clinical / surgical / radiographic observations and believe our results warrant not only further evaluation but expanded evaluation of this tissue conserving approach to THA.
The emergence of modularity in total hip arthroplasty (THA) in the 1980s and 1990s was based on t... more The emergence of modularity in total hip arthroplasty (THA) in the 1980s and 1990s was based on the fact that the benefit of these design features outweighed the risk. The use of metallic modular junctions presents a unique set of advantages and problems for use in THA. The advantages include improvement in fit and fill of the implant to bone, restoration of joint mechanics, reduced complications in revision surgery and reduction of costly inventory. However, the risks or concerns are a little harder to identify and deal with. Certainly corrosion, and fatigue failure are the two most prevalent concerns but now the specifics of fretting wear and corrosive wear increasing particulate debris and the potential biological response is having an impact on the design and potential longevity of the reconstructed hip. Material and designs are facing a shorter life expectancy than what was previously thought, mostly due to an increasing level of physical activity by the patient. Because there ...
FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certa... more FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certain conventional cementless stems. 1 Yr. follow up demonstrates positive bone remodeling filling in calcar gap with this short curved proximal conical neck sparing stem. Introduction: Architectural changes occurring in the proximal femur after THA continues to be a problem. Proximal stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and or breakage of the implant. We are seeing younger patients with higher levels of physical activity as compared to just a decade ago. A tissue sparing total hip stem provides for less tissue damage, a quicker rehab and leaves behind more infrastructure in case of future revision surgery. Patients today demand more out of the hip reconstruction and their increase activity places a higher demand on the implant. A number of the current short stems introduced into the market are no more than standard ste...
FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certa... more FEA Modeling clearly demonstrates certain style short stems have less stress shielding than certain conventional cementless stems. 1 Yr. follow up demonstrates positive bone remodeling filling in calcar gap with this short curved proximal conical neck sparing stem. Introduction: Architectural changes occurring in the proximal femur after THA continues to be a problem. Proximal stress shielding occurs regardless of fixation method. The resultant bone loss can lead to implant loosening and or breakage of the implant. We are seeing younger patients with higher levels of physical activity as compared to just a decade ago. A tissue sparing total hip stem provides for less tissue damage, a quicker rehab and leaves behind more infrastructure in case of future revision surgery. Patients today demand more out of the hip reconstruction and their increase activity places a higher demand on the implant. A number of the current short stems introduced into the market are no more than standard ste...
Purpose. To evaluate early and mid-term risk factors and dislocation rates in the posterior surgi... more Purpose. To evaluate early and mid-term risk factors and dislocation rates in the posterior surgical approach in three separate community private practices using a short curved neck-sparing total hip stem design.Material and Methods.The three senior authors performed 338 short curved neck-sparing stem designs since April 2010 to June 2014. Various cementless acetabular components were used for all three surgical centers based on preoperative and intraoperative risk factors. All cases were reviewed retrospectively for incidence of dislocation after surgery.Version and inclination of the acetabular component and version of the femoral component were assed intra-operatively prior to final implantation. Various risk factors were reviewed including surgical approach, cup position, combined cup and stem positioning, and femoral head size.There have been significant papers in the past ten years that have recommended large head diameters to reduce the chances of head/neck mechanical imping...
The aim of this paper is to review the influx of short stems for total hip arthroplasty. Not all ... more The aim of this paper is to review the influx of short stems for total hip arthroplasty. Not all short stems are created equal concerning fixation points for implant stability and length of engagement of the device in the proximal femur. Some devices are stabilized in the head, neck, metaphysis and metaphysis/diaphysis. Depending on stabilization and engagement area different short stems can have different indications, contraindications and clinical outcomes. As a result of our findings JISRF developed a classification system based on implant stabilization point and overall stem length.Keywords: short stems, head stabilized, neck stabilized, metaphyseal stabilized, metaphyseal diaphyseal stabilized
Board-certified orthopedic surgeon specializing in total hip and knee arthroplasty currently prac... more Board-certified orthopedic surgeon specializing in total hip and knee arthroplasty currently practicing in Oklahoma City, OK.
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