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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.


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.


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.