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The Bone & Joint Journal
Vol. 106-B, Issue 3 Supple A | Pages 44 - 50
1 Mar 2024
Engh, Jr CA Bhal V Hopper, Jr RH

Aims

The first aim of this study was to evaluate whether preoperative renal function is associated with postoperative changes in whole blood levels of metal ions in patients who have undergone a Birmingham Hip Resurfacing (BHR) arthroplasty with a metal-on-metal bearing. The second aim was to evaluate whether exposure to increased cobalt (Co) and chromium (Cr) levels for ten years adversely affected renal function.

Methods

As part of a multicentre, prospective post-approval study, whole blood samples were sent to a single specialized laboratory to determine Co and Cr levels, and the estimated glomerular filtration rate (eGFR). The study included patients with 117 unrevised unilateral BHRs. There were 36 females (31%). The mean age of the patients at the time of surgery of 51.3 years (SD 6.5), and they all had preoperative one-, four-, five-, and ten-year laboratory data. The mean follow-up was 10.1 years (SD 0.2).


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_12 | Pages 33 - 33
23 Jun 2023
Engh CA Bhal V Hopper RH
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When the Birmingham Hip Resurfacing (BHR) metal-on-metal implant system was approved by the United States Food and Drug Administration in 2006, a multicenter, prospective, post-approval study (PAS) was required. This study uses data from the PAS to investigate metal level and glomerular filtration rate (GFR) trends over the first decade in vivo.

Between October 2006 and March 2011, 290 primary BHR procedures were performed among 262 patients at 5 sites. Whole blood samples were sent to a single specialized laboratory to determine GFR, cobalt (Co) and chromium (Cr) levels. The population for this study consists of 117 unrevised unilateral patients with a mean age at surgery of 51.3±6.5 years who had pre-operative, 1-year, 4-year, 5-year and 10-year laboratory data. The mean follow-up for these patients that included 36 females was 10.1±0.2 years.

Median metal levels at 1-year increased relative to pre-operative values for Co (by a factor of 9.7 from 0.13 to 1.26 ppb, p<0.001) and Cr (by a factor of 2.5 from 0. 60 to 1.50 ppb, p<0.001). Metal levels subsequently remained relatively constant over time with a median 10-year value of 1.12 ppb for Co and 1.29 ppb for Cr. Based on 585 blood samples from all 117 patients, there was no relationship between GFR and Co (=−0.06, p=0.14) or Cr (=0.05, p=0.27) levels. However, lower pre-operative GFR values were associated with larger increases in Co at 1-year relative to the pre-operative level (=−0.26, p=0.005). There was no relationship between pre-operative GFR values and changes in Cr at 1 year (=−0.13, p=0.15).

Through the first decade in vivo, elevated whole blood metal levels for unilateral BHR patients do not appear to adversely affect GFR. However, patients with lower pre-operative GFR values tend to have larger increases in their Co level at 1-year.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_10 | Pages 20 - 20
1 Oct 2020
Engh CA Ho H Bhal V Housman LR Masonis JL Noble JW Hopper RH Su EP
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Introduction

The BIRMINGHAM HIP Resurfacing is a metal-on-metal (MOM) hip implant system approved by the US FDA in 2006. The approval required a multicenter, prospective, post-approval study (PAS). Our purpose is to report the current minimum 10-year results.

Methods

253 patients (280 hips) had surgery between October 2006 and December 2009 at one of 5 sites. We report revisions, survivorship, EQ-5D, Harris Hip Score (HHS), radiographic findings, and metal levels including cobalt (Co) and chromium (Cr). The mean age at surgery was 51 years, 74% male, BMI 28, osteoarthritis 95%. 243 (87%) of hips have known outcome or 10-year minimum follow-up (fup). Prior to 10 years, 5 patients died, 20 hips were revised, and 37 hips did not complete 10-year fup.


The Bone & Joint Journal
Vol. 102-B, Issue 7 Supple B | Pages 105 - 111
1 Jul 2020
Engh, Jr. CA McAsey CJ Cororaton AD Ho H Hopper, Jr. RH

Aims

The purpose of this study is to examine six types of bearing surfaces implanted at a single institution over three decades to determine whether the reasons for revision vary among the groups and how long it takes to identify differences in survival.

Methods

We considered six cohorts that included a total of 1,707 primary hips done between 1982 and 2010. These included 223 conventional polyethylene sterilized with γ irradiation in air (CPE-GA), 114 conventional polyethylene sterilized with gas plasma (CPE-GP), 116 crosslinked polyethylene (XLPE), 1,083 metal-on-metal (MOM), 90 ceramic-on-ceramic (COC), and 81 surface arthroplasties (SAs). With the exception of the COC, all other groups used cobalt-chromium (CoCr) femoral heads. The mean follow-up was 10 (0.008 to 35) years. Descriptive statistics with revisions per 100 component years (re/100 yr) and survival analysis with revision for any reason as the endpoint were used to compare bearing surfaces.


The Bone & Joint Journal
Vol. 102-B, Issue 6 Supple A | Pages 91 - 95
1 Jun 2020
Johnson, Jr. WB Engh, Jr. CA Parks NL Hamilton WG Ho PH Fricka KB

Aims

It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee arthroplasty (TKA) because conversion surgery to a primary TKA is a less complicated procedure. The purpose of this study was to determine if there is a lower threshold for revising a UKA compared with TKA based on Oxford Knee Scores (OKSs) and range of movement (ROM) at the time of revision.

Methods

We retrospectively reviewed 619 aseptic revision cases performed between December 1998 and October 2018. This included 138 UKAs that underwent conversion to TKA and 481 initial TKA revisions. Age, body mass index (BMI), time in situ, OKS, and ROM were available for all patients.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_11 | Pages 3 - 3
1 Oct 2019
Johnson WB Engh CA Hamilton WG Parks NL Ho H Fricka KB
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Introduction

It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee (TKA) because conversion surgery to a primary TKA is available. The purpose of this study was to determine if there is a lower threshold for UKA revisions compared to TKA revisions based on Oxford Knee Scores and range of motion (ROM).

Methods

We retrospectively reviewed 636 aseptic revision cases performed between 1998 and 2018. This included 137 UKAs that underwent conversion to TKA and 499 TKA revisions. Pre-revision age, body mass index (BMI), time in situ, Oxford Knee Scores, and ROM were available for all patients. T-tests were performed to determine if significant differences existed between the two groups. The minimal clinically important difference (MCID) when comparing Oxford scores between cohorts has been reported as 5 points.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_12 | Pages 63 - 63
1 Oct 2019
Engh CA McAsey CJ Cororaton A Ho H Hopper RH
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Introduction

Prior to the introduction of alternative bearing surfaces, patients were typically counseled to expect that their total hip arthroplasty (THA) using conventional polyethylene would last for 10 years. With the introduction of crosslinked polyethylene and hard-on-hard bearing surfaces, revisions related to bearing surface wear were expected to decrease. We examined six different bearing surfaces used at our institution over three decades to evaluate how the overall survivorship, reasons for revision and Harris Hip Scores have changed with time.

Methods

We identified six cohorts of patients with 754 primary hips done between 1983 and 2007. With the exception of 81 Birmingham hip resurfacings (BHR), all femoral components were straight, extensively porous-coated cylindrical (EPC) stems (AML and Prodigy). All cups were porous coated. In addition to the BHRs, the bearing surfaces included 223 conventional polyethylene (CPE) in a non-modular shell, 114 CPE in a modular shell, 116 crosslinked polyethylene (XLPE), 130 metal-on-metal (MOM), and 90 ceramic-on-ceramic (COC). The mean follow-up for all hip replacements is 13.0±6.0 years. Kaplan-Meier survivorship using revision for any reason as an endpoint with log rank testing was used to evaluate differences among groups.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_13 | Pages 24 - 24
1 Oct 2018
McAsey CJ Johnson EM Hopper RH Fricka KB Goyal N Hamilton WG Engh CA
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The statements contained in this document are solely those of the authors and do not necessarily reflect the views or policies of CMS. The authors assume responsibility for the accuracy and completeness of the information contained in this document.

Background

The Bundled Payments for Care Improvement (BPCI) initiative was introduced to reduce healthcare costs while maintaining quality. We examined data from a healthcare system comprised of five hospitals that elected to participate in the BPCI Major Joint Replacement of the Lower Extremity Model 2 initiative beginning July 1, 2015. We compared one hospital that did 439 BPCI hip cases to the four other hospitals that did 459 cases. Stratifying the data by hospital volume, we sought to determine if costs decreased during the BPCI period, how the savings were achieved, and if savings resulted in financial rewards for participation.

Methods

The Medicare data included the target cost for each episode (based on historical data from 2009–2012 for each hospital that was adjusted quarterly) and actual Part A and Part B spending for 90 days. Using 1,574 primary hip replacements, we analyzed the costs associated with the anchor hospitalization, inpatient rehabilitation, skilled nursing facilities, home health, outpatient physical therapy and readmission to compare the 898 hips done during the 16-month BPCI initiative period with the 676 hips done during the 1-year period preceding BPCI participation. Owing to the nonparametric distribution of the cost data, a Mann-Whitney U test was used to compare the higher volume hospital with the four lower volume hospitals.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_12 | Pages 69 - 69
1 Oct 2018
McAsey CJ Johnson EM Hopper RH Fricka KB Goyal N Hamilton WG Engh CA
Full Access

The statements contained in this document are solely those of the authors and do not necessarily reflect the views or policies of CMS. The authors assume responsibility for the accuracy and completeness of the information contained in this document.

Background

The Bundled Payments for Care Improvement (BPCI) initiative was introduced to reduce healthcare costs while maintaining quality. We examined data from a healthcare system comprised of five hospitals that elected to participate in the BPCI Major Joint Replacement of the Lower Extremity Model 2 initiative beginning July 1, 2015. We compared one hospital that did 507 BPCI knee cases to the four other hospitals that did 566 cases. Stratifying the data by hospital volume, we sought to determine if costs decreased during the BPCI period, how the savings were achieved, and if savings resulted in financial rewards for participation.

Methods

The Medicare data included the target cost for each episode (based on historical data from 2009–2012 for each hospital that was adjusted quarterly) and actual Part A and Part B spending for 90 days. Using 1,836 primary knee replacements, we analyzed the costs associated with the anchor hospitalization, inpatient rehabilitation, skilled nursing facilities, home health, outpatient physical therapy and readmission to compare the 1,073 knees done during the 16-month BPCI initiative period with the 763 knees done during the 1-year period preceding BPCI participation. Owing to the nonparametric distribution of the cost data, a Mann-Whitney U test was used to compare the higher volume hospital with the four lower volume hospitals.


The Bone & Joint Journal
Vol. 98-B, Issue 1_Supple_A | Pages 68 - 72
1 Jan 2016
Goodman GP Engh Jr CA

The custom triflange is a patient-specific implant for the treatment of severe bone loss in revision total hip arthroplasty (THA). Through a process of three-dimensional modelling and prototyping, a hydroxyapatite-coated component is created for acetabular reconstruction. There are seven level IV studies describing the clinical results of triflange components. The most common complications include dislocation and infection, although the rates of implant removal are low. Clinical results are promising given the challenging problem. We describe the design, manufacture and implantation process and review the clinical results, contrasting them to other methods of acetabular reconstruction in revision THA.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):68–72.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 568 - 568
1 Nov 2011
MacDonald SJ Engh CA Naudie DD Engh CA McCalden RW Thompson AE Sritulanondha S
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Purpose: A ceramic head coupled to a metal liner is a proposed new alternate bearing in THA. The authors participated in an FDA approved multicentre prospective, randomized, blinded clinical trial comparing ceramic-on-metal (CoM) to metal-on-metal (MoM) in patients receiving a THA.

Method: 390 patients received the same acetabular component and metal insert. 194 patients received a delta ceramic head (CoM) and 196 received a metal head (MoM). Metal ions were evaluated in 72 patients (36-CoM, 36-MoM). Harris Hip scores, radiographs, and metal ion levels (cobalt, chromium and titanium in serum, erythrocytes and urine) were evaluated pre-operatively and at three, 12 and 24 months.

Results: No patients were lost to follow-up. There were no differences between groups’ baseline demographics and clinical scores. At two years there were no differences in Harris Hip scores, radiographs, adverse events or postoperative complications. Both groups had overall very low median metal ion profiles with no statistically significant differences. 24 month MoM vs CoM; Serum cobalt ( g/L), mean: 1.2(+/−0.5) vs 1.1(+/−0.3), median: 0.66(range: 0.2–5.6) vs 1.0 (range: 0.3–2.7); Serum chromium ( g/L), mean: 1.1(+/−0.5) vs 1.4(+/−0.4), median: 0.86(range: 0.3–6.9) vs 1.2(range: 0.3–4.9). Urine cobalt and urine chromium ( g/day) demonstrated similar trends to serum ion levels.

Conclusion: While CoM is a new bearing surface in North America and not currently FDA or HPB approved, it has been in clinical use globally since 2006. Results of this non-inferiority RCT demonstrated no clinical outcome, metal ion, radiographic or adverse event differences between CoM and MoM cohorts.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_III | Pages 273 - 274
1 Jul 2011
MacDonald SJ Engh CA Thompson AE Sritulanondha S Naudie D Engh CA
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Purpose: Metal-on-metal articulations are an increasingly popular choice as an alternate bearing surface in total hip arthroplasty (THA) and Resurfacing implants. One advantage of a metal-on-metal bearing is the use of larger diameter femoral heads with hip simulator data demonstrating reduced wear. We performed a prospective, multicentre, randomized, blinded clinical trial comparing 28mm to 36mm metal-on-metal bearings assessing multiple validated outcome measures and serum, erythrocyte and urine metal ions.

Method: Ninety-one patients were randomized to receive a metal-on-polyethylene (34), a 28mm metal-on-metal (25) or a 36mm metal-on-metal (32) insert. All patients received the same acetabular and femoral component. Patients were evaluated pre-operatively, at 6, 12 months and annually thereafter, including an evaluation of serum, erythrocyte and urine cobalt, chromium, and titanium, outcome measures (WOMAC, SF-12, Harris Hip Score) and radiographs.

Results: At a minimum two years follow-up there were no differences in WOMAC, SF-12, Harris Hip scores or radiographs. Patients receiving metal liners had significantly (p< 0.001) elevated metal ion measurements compared with the polyethylene control group, however there were no differences between the 28mm and 36mm metal-on-metal bearings (Median serum Co (mg/L): 0.14(poly), 0.77(28mm), 0.73(36mm). Median erythrocyte Co (mg/L): 0.11(poly), 0.42(28mm), 0.42(36mm). Median urine Co(mg/day): 0.44(poly), 4.55(28mm), 5.42(36mm)). (Median serum Cr(mg/L): 0.17(poly), 1.29(28mm), 0.91(36mm). Median erythrocyte Cr(mg/ L): 1.10(poly), 1.10(28mm), 1.20(36mm). Median urine Cr(mg/day): 0.27(poly), 1.92(28mm), 2.02(36mm)).

Conclusion: Both cobalt and chromium ion measurements were significantly elevated in the blood and urine of the patients randomized to receive the metal-on-metal bearings at all time intervals. There were no differences seen between the 28mm and 36mm metal-on-metal bearings, keeping all other variables identical. The larger diameter bearing therefore provides the potential clinical advantages of improved range of motion and stability, while providing a similar metal ion profile. While reduced wear is seen with larger diameter metal-on-metal bearings in-vitro, we could not demonstrate a reduction in blood or urine metal ion levels in-vivo.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_I | Pages 103 - 103
1 Mar 2008
Naudie D Kitamura N Leung S Engh CA
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This study evaluates forty-four consecutive autopsy specimens of the senior author’s own patients in attempt to locate and measure periacetabular bone defects and correlate this information with their communication pathways with the joint space.

The purpose of this study was to evaluate autopsy retrieved hemipelves of previously well-functioning total hip arthroplasties (THAs) with computed tomography (CT) to better understand patterns of osteolysis around modular uncemented acetabular components.

Forty-four hemipelves containing titanium porous-coated modular acetabular components were retrieved at autopsy, imaged with CT, and analyzed to determine the location and volume of osteolytic lesions. The mean age of the patients at the time of surgery was seventy years. The mean time in situ for the implants was eight years.

A total of forty-six osteolytic lesions were identified in twenty-eight of the forty-four cases (64%). Thirty-one of forty-six lesions (67%) had one or more apparent communications with the joint space. We identified four types of communication pathways between osteolytic lesions and the joint space: around the rim, through a central dome hole, in association with a screw or screw hole, or around a non-ingrown interface. The mean volume of lesions that had a clear communication pathway was significantly larger than those lesions that did not have a clear communication pathway (p=0.012). Thirteen of the fifteen lesions that did not have a clear communication with the joint space represented bone defects that had existed prior to total hip arthroplasty.

Osteolysis was commonly observed at early time intervals around modular uncemented acetabular components. The communication with the joint space is important for developing osteolysis, as well as in the detection of true osteolytic lesions.


The Journal of Bone & Joint Surgery British Volume
Vol. 83-B, Issue 5 | Pages 686 - 690
1 Jul 2001
Jana AK Engh CA Lewandowski PJ Hopper RH Engh CA

We studied the results of total hip arthroplasty (THA) using AML porous-coated femoral components at a mean follow-up of 11 years in a non-selected, consecutive series of patients with rheumatoid arthritis. We reviewed 64 patients with 82 primary THAs using these components. There were seven men (8 hips) and 57 women (74 hips) with a mean age of 55.1 years (24 to 80) at the time of surgery.

Nine patients (11 hips) died before the two-year follow-up. Of the remaining 71 hips, only one stem was revised for aseptic loosening. Survivorship for the stems was 98.1% (95% confidence interval (CI) 94.5 to 100.0) at ten years, using a life-table analysis, with revision for any reason as an endpoint. Of the 70 unrevised stems, 66 (94%) had bony ingrowth, while four (6%) were radiologically loose at the most recent follow-up (mean 11.4 years). Our study shows the excellent long-term results which can be achieved with porous-coated femoral components in patients with rheumatoid arthritis.


The Journal of Bone & Joint Surgery British Volume
Vol. 82-B, Issue 7 | Pages 948 - 951
1 Sep 2000
Sychterz CJ Engh CA Young AM Hopper RH Engh CA

At yearly intervals we compared the radiological wear characteristics of 81 alumina ceramic femoral heads with a well-matched group of 43 cobalt-chrome femoral heads. Using a computer-assisted measurement system we assessed two-dimensional penetration of the head into the polyethylene liner. We used linear regression analysis of temporal data of the penetration of the head to calculate the true rates of polyethylene wear for both groups. At a mean of seven years the true rate of wear of the ceramic group was slightly greater (0.09 mm/year, SD 0.07) than that of the cobalt-chrome group (0.07 mm/year, SD 0.04). Despite the numerous theoretical advantages of ceramic over cobalt-chrome femoral heads, the wear performance in vivo of these components was similar.


The Journal of Bone & Joint Surgery British Volume
Vol. 78-B, Issue 2 | Pages 270 - 275
1 Mar 1996
Hooten JP Engh CA Heekin RD Vinh TN

Two acetabula which contained large bone allografts introduced at revision arthroplasty were obtained at post-mortem. The allografts had been placed in superior defects to support cementless acetabular components, and both hips were functioning well at the time of death. Clinical radiographs demonstrated apparent healing of graft to host bone, no graft collapse and stability of the acetabular components. Microscopic examination of sections through these specimens showed that the bulk allografts were encapsulated in fibrous tissue. Vascularity was increased at the host-graft interface, but there was limited evidence of bone union between the graft and the host. In the few areas where union had occurred, revascularisation extended no more than 2 mm beyond the graft-host interface.

Within the body of the graft, the acellular matrix of trabecular bone maintained structural integrity up to 48 months after surgery. In areas where the allograft was adjacent to an implant, there was fibrous tissue orientated parallel to the implant surface. The acetabulum which contained a porous-coated component showed evidence of bone growth into the porous surface where it was in contact with viable host bone. No ingrowth occurred in areas where the porous coating was in contact with the graft. Although the grafts were functioning well, allograft revascularisation and remodelling were minimal, and the radiological appearance of healing did not correlate with histological findings.