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The influence of prosthesis design on stress shielding in cementless total hip replacement
104
The Journal
of Arthroplasty
Vol. 9 No. 1 February
For uitimate viability, any bone graft musl be: 1) Of appropriate size, 2) Have sufficient vascularity available, 3) Be firmly fixed, and 4) Be loaded in compression. In this femoral revision technique, the graft is: 1) Morselized, 2) Contained in a vascular envelope, 3) Fixed by PMMA, and 4) Loaded in compression by the Collarless Polished Taper Stem. SUMMABY: Exchange femoral arthroplasty with compacted morselized bank bone and cemented collarless polished taper stem promotes the building of a new proximal femoral envelope which shows no attenuation or deterioration over time.
PAPER
of an stablIlt> a three-
Methods and MalewIs. The fmlre clement model was generated from CT uxm data of a human proxrmal femur mlplanled wlh a commercially available prosthesIs Loads were apphed lo the femoral head and greater lrochanter lo s,mulatc smgle-leg stance and stair chmbmg Friction heha\lor of the bone-implant interface \‘las modeled using non-lmear mterface elements to snnulate a smooth, press-fit stem and a porous coated ~lem Relative molmns were calculated along Ihe medial surface of the prosthesis at the calcar. the upper one-quxter. the lover one-quarrer and the stem “P Fmdmps Av~al mot,on was greater under smgle-stance loadmg while ~ra"s~crcc mohons were greater under sla~r chmblng loads (mau~mum of eight llrnes higher I” the calcar loca(~on) For both loading conditions the porous coated sfem showed lower axml relatwe motions than the smo~,th ~fem by about one-third and lower transverse relatwe mo,,ons by about one-fourth except at the stem "p whcrc tbc
The total relal,ve
mol,o"~
\vere below
70 mlcr""s
excep, m the most provlmal locahon where the relabve mofaons were 17@ morons for the smooth stem and I40 morons for the porous coated stem Con~lusmn press-filled proximally
Porous coaled femoral stems prowde grearer stahllay than a smoolh Implam Star cllmbmg loads generate large (ransverse motwns whwh could be detrImental to nnplanl srab,hlv and bony mgrowlh
PAPER 'XRC SEISLDINQ
Ronald M.D.,
#8
INFL"ENCR OF PROSTEESIS IN CRtUNTLR ss TOTAL EIP
E. Talbert, Freeno, CA;
M.D. William
Beaumont, L.
p <
.03).
CONCLUSION: different different of stress design.
This study shows that implants of two designs and materials cause significantly degrees of strees shielding. The phenomenon shielding can be controlled through implant
PAPER
lntroductmn Implant stablhty IS crucial to the long-term performanu uncemented total htp replacement The effects of porous coatmg on implant was studled, under smgle-leg stance and stax cllmbmg loads. usmg dlmensmnal fmlte element model
were about the same
Each patient underwent DEXA scanning of both hips. BO"f2 density was then tabulated by Gwen zones and the density of each zone in the implanted femur was expressed as a percentage of the density in the corresponding zone of the contralateral normal hip. I" Group A, lees density was see" in all zones, with the greatest difference being 55% of normal in zone 7. Group B showed all zones to be greater than 95% of normal except zone 7 (83%). Comparing equivalent ~0x8 in the two groups, the differences were statistrcally significant for all zones except zone 4 (matched t-test,
#7
THE EFFECT OF POROUS COATING AND LOADING CONDII’IONS ON TOTAL HIP FEMORAL STEM STABILII’Y Fu Hau. Ph D, Houston, Jeffrey D Reuben, MD Ph D , Houston, John Akm. Ph D , Houston. TX
values
1994
Bargar,
DESIGN ON REPLACEMENT
TX;
Thomas H.D.,
STRESS
P. Gross,
#9
ROLE OF HYDROXYLAPATITE COATING IN POSTOPERATIVE RECOVERY AFTER CEMENTLESS HIP REPLACEMENT A PROSPECTIVE RANDOMIZED TRIAL C. S. Ranawat. MD, New York, NY, Rajiv G. Deshmukh. MBMS. FRCS. William F. Flynn, Jr.. MD Purms~: To study the role of hydroxylapatite coating on femoral component in reducing thigh pain and improving quality of function after noncemented hip replacements. Conclusion: Hydroxylapatite coated femoral stems appear to offer an advantage by reducing the severity and incidence of thigh pain Sianlflcance: Cementless hip replacements have overtaken cemented ones as the preferred procedure in young, active individuals. thigh pain and delay in resuming normal activity are reported by many patients. Hydroxylapatite coating can enhance recovery. of Method.Results and Discussion: A prospective randomized study is underway at our institution using a noncemented hip replacement system that provides a customized fit in the femur using a range of dlstel diameters and proximal geometries. All implants have plasma sprayed porous coating proximally. The patients are randomized into two groups, one of which receive hydroxylapatite coated implants. The study is divided into 3 phases. Phase 1 compares the thigh pain incidence and severity as well as return to normal function in the 2 groups. Phases 2 and 3 will compare long term clinical and radiological results. Thigh pain was graded into 3 grades based on it’s severity and frequency. Visual analog scales (0 to IO) were used for mail intervlews to eliminate observer bias. Recovery and return to function were judged by the need to use cane or crutch and presence or absence of limp. The first 100 consecutive operations performed by a smgle surgeon with a minimum followup of 6 months are included in this report, The degree of thigh pain experienced by patients receiving the hydroxylapatite coated implants was less though the difference was not highly significant (p=.O55). The maximum benefit was perceived by males with body weight below 165 Ibs. No difference was found in the incidence of limp and the use of cane or crutch. The role of hydroxylapatite coaling in cementless hip replacements warrants further study in view of these findings.
Sacramento,
CA
Femoral implant design may have a strong INTRODUCTION: influence on stress shielding of the proximal femur resulting in varying degrees of bone resorption. This study compares matched patients with Cementless femoral hip lkstheses of two v&y different design philosophies One group (A) received an AML using DEXA analysis. implant (5/S coated, CT-Co, DePuy) which relies on distal ingrowth for fixation and tranemits axial, torsional, and bending loads distally. The other group (B) received a CT-based custom implant (Titanium, Techmadica) with proximal ingrowth pads and a parametric design that maximizes proximal endosteal contact to transmit axial and torsional loads, incorporating a cylindrical smooth stem distally to transmit bending loads. Eight patients in each of two NSZRODS AND IULTERSALS: groups were matched for age (mean = 60 yrs), weight (ew. 168.9 lbe), qender 15 females, 3 males), diaqnosis iosteoarthritip),;ace (c8ucasian), and length of hollow up (3 to 4 years). All patients had an excellent clinical result (Harris ecore > 90), and had a normal implants showed radiographic opposite hip and all evidence of bone ingrowth (Engh's criteria).
#lo
PAPER
CONCOMITANT
REPLACE"ENT Bernasek, M.D.,
OSTEOTOMY WITH Michael D. Ciepiela, Kenneth A. Gustke,
PURPOSE: Evaluation femoral anatomy required arthroplasty. CONCLUSION: Shortening osteotomy heals predictably with standard prostheses of abductor musculature. SIGNIFICANCE: This arthroplasty using standard excessive femoralanteversio" femur 1s necessary.
of
PRIMARY
M.D.,
total hip o*teotomy
TOTAL
HIP
N.D., Thomas Tampa, Florida. pat;ents to
L.
i" whom fac111tate
or
and and
derotatrunal femoral facilitates arthroplasty allows anatomic alignment
technique prostheses or where
fac111tates L" patients shortening
of
hip with the
The Journal
of Arthroplasty
Vol. 9 No. 1 February
For uitimate viability, any bone graft musl be: 1) Of appropriate size, 2) Have sufficient vascularity available, 3) Be firmly fixed, and 4) Be loaded in compression. In this femoral revision technique, the graft is: 1) Morselized, 2) Contained in a vascular envelope, 3) Fixed by PMMA, and 4) Loaded in compression by the Collarless Polished Taper Stem. SUMMABY: Exchange femoral arthroplasty with compacted morselized bank bone and cemented collarless polished taper stem promotes the building of a new proximal femoral envelope which shows no attenuation or deterioration over time.
PAPER
of an stablIlt> a three-
Methods and MalewIs. The fmlre clement model was generated from CT uxm data of a human proxrmal femur mlplanled wlh a commercially available prosthesIs Loads were apphed lo the femoral head and greater lrochanter lo s,mulatc smgle-leg stance and stair chmbmg Friction heha\lor of the bone-implant interface \‘las modeled using non-lmear mterface elements to snnulate a smooth, press-fit stem and a porous coated ~lem Relative molmns were calculated along Ihe medial surface of the prosthesis at the calcar. the upper one-quxter. the lover one-quarrer and the stem “P Fmdmps Av~al mot,on was greater under smgle-stance loadmg while ~ra"s~crcc mohons were greater under sla~r chmblng loads (mau~mum of eight llrnes higher I” the calcar loca(~on) For both loading conditions the porous coated sfem showed lower axml relatwe motions than the smo~,th ~fem by about one-third and lower transverse relatwe mo,,ons by about one-fourth except at the stem "p whcrc tbc
The total relal,ve
mol,o"~
\vere below
70 mlcr""s
excep, m the most provlmal locahon where the relabve mofaons were 17@ morons for the smooth stem and I40 morons for the porous coated stem Con~lusmn press-filled proximally
Porous coaled femoral stems prowde grearer stahllay than a smoolh Implam Star cllmbmg loads generate large (ransverse motwns whwh could be detrImental to nnplanl srab,hlv and bony mgrowlh
PAPER 'XRC SEISLDINQ
Ronald M.D.,
#8
INFL"ENCR OF PROSTEESIS IN CRtUNTLR ss TOTAL EIP
E. Talbert, Freeno, CA;
M.D. William
Beaumont, L.
p <
.03).
CONCLUSION: different different of stress design.
This study shows that implants of two designs and materials cause significantly degrees of strees shielding. The phenomenon shielding can be controlled through implant
PAPER
lntroductmn Implant stablhty IS crucial to the long-term performanu uncemented total htp replacement The effects of porous coatmg on implant was studled, under smgle-leg stance and stax cllmbmg loads. usmg dlmensmnal fmlte element model
were about the same
Each patient underwent DEXA scanning of both hips. BO"f2 density was then tabulated by Gwen zones and the density of each zone in the implanted femur was expressed as a percentage of the density in the corresponding zone of the contralateral normal hip. I" Group A, lees density was see" in all zones, with the greatest difference being 55% of normal in zone 7. Group B showed all zones to be greater than 95% of normal except zone 7 (83%). Comparing equivalent ~0x8 in the two groups, the differences were statistrcally significant for all zones except zone 4 (matched t-test,
#7
THE EFFECT OF POROUS COATING AND LOADING CONDII’IONS ON TOTAL HIP FEMORAL STEM STABILII’Y Fu Hau. Ph D, Houston, Jeffrey D Reuben, MD Ph D , Houston, John Akm. Ph D , Houston. TX
values
1994
Bargar,
DESIGN ON REPLACEMENT
TX;
Thomas H.D.,
STRESS
P. Gross,
#9
ROLE OF HYDROXYLAPATITE COATING IN POSTOPERATIVE RECOVERY AFTER CEMENTLESS HIP REPLACEMENT A PROSPECTIVE RANDOMIZED TRIAL C. S. Ranawat. MD, New York, NY, Rajiv G. Deshmukh. MBMS. FRCS. William F. Flynn, Jr.. MD Purms~: To study the role of hydroxylapatite coating on femoral component in reducing thigh pain and improving quality of function after noncemented hip replacements. Conclusion: Hydroxylapatite coated femoral stems appear to offer an advantage by reducing the severity and incidence of thigh pain Sianlflcance: Cementless hip replacements have overtaken cemented ones as the preferred procedure in young, active individuals. thigh pain and delay in resuming normal activity are reported by many patients. Hydroxylapatite coating can enhance recovery. of Method.Results and Discussion: A prospective randomized study is underway at our institution using a noncemented hip replacement system that provides a customized fit in the femur using a range of dlstel diameters and proximal geometries. All implants have plasma sprayed porous coating proximally. The patients are randomized into two groups, one of which receive hydroxylapatite coated implants. The study is divided into 3 phases. Phase 1 compares the thigh pain incidence and severity as well as return to normal function in the 2 groups. Phases 2 and 3 will compare long term clinical and radiological results. Thigh pain was graded into 3 grades based on it’s severity and frequency. Visual analog scales (0 to IO) were used for mail intervlews to eliminate observer bias. Recovery and return to function were judged by the need to use cane or crutch and presence or absence of limp. The first 100 consecutive operations performed by a smgle surgeon with a minimum followup of 6 months are included in this report, The degree of thigh pain experienced by patients receiving the hydroxylapatite coated implants was less though the difference was not highly significant (p=.O55). The maximum benefit was perceived by males with body weight below 165 Ibs. No difference was found in the incidence of limp and the use of cane or crutch. The role of hydroxylapatite coaling in cementless hip replacements warrants further study in view of these findings.
Sacramento,
CA
Femoral implant design may have a strong INTRODUCTION: influence on stress shielding of the proximal femur resulting in varying degrees of bone resorption. This study compares matched patients with Cementless femoral hip lkstheses of two v&y different design philosophies One group (A) received an AML using DEXA analysis. implant (5/S coated, CT-Co, DePuy) which relies on distal ingrowth for fixation and tranemits axial, torsional, and bending loads distally. The other group (B) received a CT-based custom implant (Titanium, Techmadica) with proximal ingrowth pads and a parametric design that maximizes proximal endosteal contact to transmit axial and torsional loads, incorporating a cylindrical smooth stem distally to transmit bending loads. Eight patients in each of two NSZRODS AND IULTERSALS: groups were matched for age (mean = 60 yrs), weight (ew. 168.9 lbe), qender 15 females, 3 males), diaqnosis iosteoarthritip),;ace (c8ucasian), and length of hollow up (3 to 4 years). All patients had an excellent clinical result (Harris ecore > 90), and had a normal implants showed radiographic opposite hip and all evidence of bone ingrowth (Engh's criteria).
#lo
PAPER
CONCOMITANT
REPLACE"ENT Bernasek, M.D.,
OSTEOTOMY WITH Michael D. Ciepiela, Kenneth A. Gustke,
PURPOSE: Evaluation femoral anatomy required arthroplasty. CONCLUSION: Shortening osteotomy heals predictably with standard prostheses of abductor musculature. SIGNIFICANCE: This arthroplasty using standard excessive femoralanteversio" femur 1s necessary.
of
PRIMARY
M.D.,
total hip o*teotomy
TOTAL
HIP
N.D., Thomas Tampa, Florida. pat;ents to
L.
i" whom fac111tate
or
and and
derotatrunal femoral facilitates arthroplasty allows anatomic alignment
technique prostheses or where
fac111tates L" patients shortening
of
hip with the