[Show abstract][Hide abstract] ABSTRACT: Background:
The choice of bearing articulation for total hip arthroplasty in younger patients is amenable to debate. We compared mid-term patient-reported outcomes and survivorship across 2 different bearing articulations in a young patient cohort.
We reviewed patients with cobalt-chrome or oxidized zirconium on highly crosslinked polyethylene who were followed prospectively between 2004 and 2012. Kaplan-Meier analysis was used to determine predicted cumulative survivorship at 5 years with all-cause and aseptic revisions as the outcome. We compared patient-reported outcomes, including the Harris hip score (HHS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Short-form 12 (SF-12) scores.
A total of 622 patients were followed during the study period. Mean follow-up was 8.2 (range 2.0-10.6) years for cobalt-chrome and 7.8 (range 2.1-10.7) years for oxidized zirconium. Mean age was 54.9 ± 10.6 years for cobalt-chrome and 54.8 ± 10.7 years for oxidized zirconium. Implant survivorship was 96.0% (95% confidence interval [CI] 94.9%-97.1%) for cobalt-chrome and 98.7% (95% CI 98.0%-99.4%) for oxidized zirconium on highly crosslinked polyethylene for all-cause revisions, and 97.2% (95% CI 96.2%-98.2%) for cobalt-chrome and 99.0% (95% CI 98.4%-99.6%) for oxidized zirconium for aseptic revisions. An age-, sex- and diagnosis-matched comparison of the HHS, WOMAC and SF-12 scores demonstrated no significant changes in clinical outcomes across the groups.
Both bearing surface couples demonstrated excellent mid-term survivorship and outcomes in young patient cohorts. Future analyses on wear and costs are warranted to elicit differences between the groups at long-term follow-up.
Preview · Article · Jan 2016 · Canadian journal of surgery. Journal canadien de chirurgie
[Show abstract][Hide abstract] ABSTRACT: Aims
The purpose of this study was to compare the long-term results of primary total hip arthroplasty (THA) in young patients using either a conventional (CPE) or a highly cross linked (HXLPE) polyethylene liner in terms of functional outcome, incidence of osteolysis, radiological wear and rate of revision.
We included all patients between the ages of 45 and 65 years who, between January 2000 and December 2001, had undergone a primary THA for osteoarthritis at our hospital using a CPE or HXLPE acetabular liner and a 28 mm cobalt-chrome femoral head. From a total of 160 patients, 158 (177 hips) were available for review (CPE 89; XLPE 88). The mean age, body mass index (BMI) and follow-up in each group were: CPE: 56.8 years (46 to 65); 30.7 kg/m2 (19 to 58); 13.2 years (2.1 to 14.7) and HXLPE: 55.6 years (45 to 65); BMI: 30 kg/m2 (18 to 51); 13.1 years (5.7 to 14.4).
The mean Harris hip score (HHS) at final follow-up was 89.3 for the CPE group and 90.9 for the HXLPE group (p = 0.078). Osteolysis was present around 15 acetabular (17%) and 16 femoral (18%) components in the CPE hips compared with none (0%) in the HXLPE hips. The mean radiological linear wear of the CPE liners was 0.11 mm/year compared with 0.035 mm/year for the HXLPE liners (p = 0.006). The cumulative implant survival, with revision for polyethylene wear as the endpoint, was 86% (95% confidence interval 78 to 94) in the CPE group and 100% in the HXLPE group at 13 years (numbers at risk at 13 years - CPE: 65, XLPE: 61).
This study shows that HXLPE liners are associated with significantly less osteolysis and a lower rate of revision THA than CPE liners at long-term follow-up.
Take home message: The findings of this study highlight the clinical benefits of using HXLPE liners in THA and support the routine use of the material in order to improve implant longevity and to decrease the number of patients needing revision for aseptic osteolysis.
Full-text · Article · Jan 2016 · The Bone & Joint Journal
[Show abstract][Hide abstract] ABSTRACT: Background:
Wear in posterior-stabilized (PS) polyethylene tibial inserts depends on component position, limb alignment, and ligament balancing. Valgus-varus constrained (VVC) inserts are likely to be affected similarly. We aimed to compare wear characteristics of VVC and PS inserts and identify associated factors.
This was a retrieval analysis (macroscopic and radiographic) of all 18 VVC liners collected from patients who underwent revision surgery from 1999 to 2011. These patients were matched to another group with PS inserts who underwent revision in the same time period.
There was significantly more damage in the posts of the VVC group (13.0 ± 5.0, compared to 4.7 ± 1.9 in the PS group; P < .001). Within the VVC group, the total damage score and cold flow damage were significantly higher with excessive joint line changes (≥5 mm; P = .01). The excessive joint line elevation was associated with rotational wear pattern of the post (P = .004). Damage scores were increased with femoral component malposition (P = .04), anterior tibial slope (P = .04), and tibial component malposition (P = .04).
Joint line elevation, femoral and tibial component malposition, and anterior tibial slope resulted in significantly more wear in the VVC inserts. Joint line elevation of >5 mm resulted in wear of the medial and lateral aspects of the post, femoral valgus resulted in cold flow wear of the anterior post, and tibial valgus and anterior slope resulted in wear of lateral aspect of the post.
No preview · Article · Dec 2015 · The Journal of arthroplasty
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to compare clinical outcomes of total knee arthroplasty (TKA) after manipulation under anaesthesia (MUA) for post-operative stiffness with a matched cohort of TKA patients who did not requre MUA. In total 72 patients (mean age 59.8 years, 42 to 83) who underwent MUA following TKA were identified from our prospective database and compared with a matched cohort of patients who had undergone TKA without subsequent MUA. Patients were evaluated for range of movement (ROM) and clinical outcome scores (Western Ontario and McMaster Universities Arthritis Index, Short-Form Health Survey, and Knee Society Clinical Rating System) at a mean follow-up of 36.4 months (12 to 120). MUA took place at a mean of nine weeks (5 to 18) after TKA. In patients who required MUA, mean flexion deformity improved from 10 degrees (0 degrees to 25 degrees) to 4.4 degrees (0 degrees to 15 degrees) (p < 0.001), and mean range of flexion improved from 79.8 degrees (65 degrees to 95 degrees) to 116 degrees (80 degrees to 130 degrees) (p < 0.001). There were no statistically significant differences in ROM or functional outcome scores at three months, one year, or two years between those who required MUA and those who did not. There were no complications associated with manipulation. At most recent follow-up, patients requiring MUA achieved equivalent ROM and clinical outcome scores when compared with a matched control group. While other studies have focused on ROM after manipulation, the current study adds to current literature by supplementing this with functional outcome scores.
No preview · Article · Dec 2015 · Bone and Joint Journal
[Show abstract][Hide abstract] ABSTRACT: This study examines the damage and wear on the polyethylene (PE) inserts from 52 retrieved Genesis II total knee replacements to identify differences in tribological performance between matched pairs of cobalt-chromium (CoCr) and oxidized zirconium (OxZr) femoral components. Observer damage scoring and microcomputed tomography were used to quantify PE damage and wear, respectively. No significant differences were found between CoCr and OxZr groups in terms of PE insert damage, surface penetration, or wear. No severe damage such as cracking or delamination was noted on any of the 52 PE inserts. Observer damage scoring did not correlate with penetrative or volumetric PE wear. The more costly OxZr femoral component does not demonstrate clear tribological benefit over the standard CoCr component in the short term with this total knee replacement design.
No preview · Article · Aug 2015 · The Journal of arthroplasty
[Show abstract][Hide abstract] ABSTRACT: Although it is understood that backside damage occurs in polyethylene acetabular liners, the effect of highly crosslinked polyethylene, which has completely replaced conventional polyethylene, has yet to be examined.
The purpose of this study was to answer the following questions: (1) With conventional polyethylene (CPE), did the acetabular design make a difference in backside wear? (2) Is there a difference in backside damage between CPE and crosslinked polyethylene (XLPE) liners? (3) With XLPE, is the difference in backside wear between designs still present? (4) Is there any difference in backside damage in various zones on backside of individual liners?
This single-institution retrieval analysis involved visual damage scoring on the backside of 233 polyethylene liners implanted between 2002 and 2011. The liners were retrieved from either polished/dovetail cups (PD) or roughened/wire cups (RW) made by two different manufacturers. The inserts were divided into four groups: PD-CPE (n = 105), PD-XLPE (n = 16), RW-CPE (n = 99), and RW-XLPE (n = 13). Aseptic loosening and polyethylene wear were the predominant reasons for revision of CPE liners, whereas instability and infection were the common reasons for revision of XLPE liners. The time in situ (TIS) was shorter for the XLPE liners as compared with the CPE liners (PD-CPE: 8.5 years [SD 4.4]; RD-CPE: 9.5 [SD 4.8]; PD-CPE: 3.8 [SD 3.7]; RD-XLPE: 4.0 [SD 4.3]). The backside of each liner was divided into five zones and graded initially from a scale of 0 to 3 for seven different damage modes by one observer. There was substantial interobserver (kappa 0.769) and intraobserver (0.736) reliability on repeat scoring. To compare the effects of crosslinking, a subset of the conventional polyethylene liners was matched to the crosslinked liners based on TIS, resulting in 16 per group for the two PD types and 13 per group for the two RW types.
Total damage scores in the RW-CPE (19 ± 7) group were greater (p < 0.001) than the PD-CPE group (8 ± 4). Damage was reduced with XLPE (p = 0.02) only for the RW-XLPE (9 ± 9) versus RW-CPE-type sockets (4 ± 4). There was no difference (p = 0.16) between the RW-XLPE group and the PD-XLPE group. Damage scores in the peripheral zone of the locking mechanisms were higher for RW-CPE (4 ± 3) compared with PD-CPE (1.4 ± 1.0, p < 0.001) and RW-XLPE (1.3 ± 1.3, p = 0.02). Damage was greater (p < 0.001) within the superior zones (7 ± 4) compared with the inferior zones (3.0 ± 2.8) of all liners.
The current study shows greater backside damage for CPE in the roughened, wire lock cups. XLPE was shown to be more resistant to backside damage for both socket designs.
Although the polished/dovetail cups seem to cause less backside damage in the CPE liners than roughened/wire cups, the use of XLPE liners has been shown to protect the liner from backside damage in either cup design. If an acetabular shell has a functional locking mechanism, surgeons should not worry about cup design when undertaking isolated liner revision using XLPE liners.
No preview · Article · Jul 2015 · Clinical Orthopaedics and Related Research
[Show abstract][Hide abstract] ABSTRACT: Hard-on-hard bearings for total hip arthroplasty continue to warrant analysis even though crosslinked polyethylene is performing very well. Ceramic-on-metal (CoM) has low in vitro wear and did well in an early clinical trial. We report on a prospective, randomized, multicenter investigational device trial comparing CoM with metal-on-metal (MoM).
(1) Is there a difference in the number or type of revisions comparing CoM with MoM? (2) Are cobalt and chromium metal levels different for CoM and MoM THA?
Between August 2005 and October 2006, of 1015 patients screened, 390 patients were enrolled at 11 centers and randomized to 194 CoM and 196 MoM bearings. There was no difference in the preoperative patient demographics between the study groups. Mean followup was 50 months (range, 22-75 months). Seventy-two patients from two centers had metal level analysis.
With the numbers available, there was no difference in the proportion of patients undergoing revisions between the MoM and the CoM cohorts (MOM: 3% [six of 196]; COM: 1.5% [three of 194]; p = 0.50). Four MoM revisions were unrelated to the bearing surface. Two had bearing surface-related reoperations, one for an aseptic lymphocyte-dominated vasculitis-associated lesion and one for elevated metal levels with acetabular malposition. None of the CoM revisions were related to the bearing surface. The metal level analysis revealed that in contrast to the CoM, the MoM bearing group had increasing values of erythrocyte and serum cobalt from 1 to 5 years (CoM erythrocyte 0.45-0.55 ppb, p = 0.11 and CoM serum 0.88-0.85, p = 0.55, and MoM erythrocyte 0.32-0.51 ppb, p < 0.01 and MoM serum 0.65-1.01 ppb, p < 0.01). In addition, the MoM cobalt levels in erythrocytes and serum at 5 years were more variable than at 1 year (erythrocyte interquartile range [IQR], 0.26-0.44 to 0.31-1.21 ppb and serum IQR, 0.42-0.80 to 0.64-2.20 ppb, p < 0.02 for both).
Although both bearings performed well at short-term followup, the CoM bearing group had no wear-related revisions and maintained consistently low metal levels. The MoM cobalt elevations may be important considering recent reports of taper corrosion. This CoM bearing was approved by the FDA but withdrawn from the market because of low sales. If it were available, the authors would not use CoM until long-term data were available. The bearing would have to outperform crosslinked polyethylene because it is unlikely that CoM metal levels will return to normal.
Level I, therapeutic study.
Full-text · Article · Jul 2015 · Clinical Orthopaedics and Related Research
[Show abstract][Hide abstract] ABSTRACT: Porous metal acetabular augments have become widely used to fill bony defects in patients undergoing revision total hip arthroplasty. The objective of this study was to determine whether the currently offered size range of the augments is appropriate for surgical needs.
We reviewed the cases of all patients at 1 centre with a porous revision shell, and when an augment was used we recorded the patient and implant characteristics.
We reviewed the cases of 281 patients, and augments were used in 24. Augment diameter was skewed toward the small end (p < 0.001), although thickness was not (p = 0.05); 21 of 24 augments were those with the smallest 3 diameters and thicknesses.
Given the sizes used, the full range of inventory provided by the manufacturer may be unnecessary, as surgeons will likely attempt a larger shell before a larger augment.
Full-text · Article · Feb 2015 · Canadian journal of surgery. Journal canadien de chirurgie
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to assess the feasibility, effectiveness and costs of a web-based follow-up compared to in-person assessment following primary total hip or total knee arthroplasty. Patients who were at least 12 months postoperative were randomized to follow-up method. We excluded patients who had revision surgery, osteolysis, complications or identified radiographic issues. 229 patients (118 Web, 111 in-person) completed the study. There were no patients who had an issue missed by the web-based follow-up. Patients in the web-based group travelled less (28.2 km vs 103.7 km, (p < 0.01)), had lower associated costs ($10.45 vs $21.36, (p < 0.01)) and took less time to complete (121.7 min web vs 228.7 min usual). Web-based follow-up is a feasible, clinically effective alternative with lower associated costs than in-person clinic assessment.
No preview · Article · Sep 2014 · The Journal of Arthroplasty
[Show abstract][Hide abstract] ABSTRACT: Background:
Highly crosslinked polyethylene (XLPE) is believed to demonstrate better wear resistance than conventional polyethylene (CPE) in total hip arthroplasty.
The purpose of this study was to compare visual damage scores and micro-CT measurements of penetration, a surrogate for wear, between matched retrieved XLPE and CPE acetabular liners.
Thirteen XLPE acetabular liners were matched in terms of implant design (all were of the same design), patient age, sex, liner dimensions, duration of implantation, and reason for revision to a group of CPE liners that were retrieved in the same time period. Penetration resulting from the combination of wear and creep in the two groups of liners was measured with micro-CT. Surface damage was scored by two blinded observers using a surface damage system that considers the seven common damage modes: pitting, scratching, burnishing, abrasions, impingement, embedded debris, and delamination, and wear patterns were documented.
There was no difference (p=0.32) in total damage score between the XLPE group (14±4) and the CPE group (15±5). However, there was three times greater penetration (odds ratio, 3.1; confidence interval, 2.3-5.1; p<0.001) in the CPE group (0.18±0.09 mm/year) than in the XLPE group (0.05±0.07 mm/year). There was less volumetric loss in XLPE (82±SD 134 mm3) versus the CPE group (350±SD 342 mm3; p=0.017).
XLPE liners undergo less penetration as a result of creep and wear than CPE liners based on quantitative measurements provided by micro-CT, which was not apparent using damage scoring alone. This demonstrates the use of three-dimensional imaging techniques such as micro-CT for quantifying wear in retrieval studies.
In this study, XLPE had less wear but similar damage scores than CPE, allaying concerns that the beneficial wear properties of XLPE might come with a tradeoff arising from the increased brittleness of that material.
No preview · Article · Aug 2014 · Clinical Orthopaedics and Related Research
[Show abstract][Hide abstract] ABSTRACT: Background
Quantitative measurements of damage and wear in orthopaedic components retrieved from patients during revision surgery can provide valuable information. However, to perform these measurements there needs to be an estimate of the original, unworn geometry of the component, often requiring multiple scans of the various sizes of components that have been retrieved. The objective of this study was to determine whether the articular and backside surfaces could be independently segmented from a micro-CT reconstruction of a tibial insert, such that a tibial insert of one thickness could be used as a reference for a tibial insert of a different thickness.
New tibial inserts of a single width but six different thicknesses were obtained and scanned with micro-CT. An automated method was developed to computationally segment the articular and backside surfaces of the components. Variability between intact and extracted components was determined.
The deviations between the comparisons of the extracted surfaces (range, 0.0004 to 0.010 mm) were less (p < 0.001) than the baseline deviation between the intact surfaces (range, 0.0002 to 0.053 mm).
An extracted surface from one insert thickness could be used to accurately represent the surface of an insert of a different thickness. This greatly enhances the feasibility of performing retrieval studies using micro-CT as a quantitative tool, by reducing the costs and time associated with acquiring, scanning, and reconstructing multiple reference tibial insert geometries. This will add greater detail to studies of retrieved implants, to better establish how implants are functioning in vivo.
[Show abstract][Hide abstract] ABSTRACT: We sought to determine what dimensional changes occurred from wear testing of a total knee implant, as well as whether any changes developed within the polyethylene subsurface. Three fixed bearing implants underwent wear simulator testing to 6.1 million cycles. Gravimetric analysis and micro-CT scans were performed pre-test, mid-test, and post-test. Wear volume and surface deviations were greater during 0-3.2 million cycles (91 ± 12 mm3) than from 3.2-6.1 million cycles (52 ± 18 mm3). Deviations (wear and creep) occurred across all surfaces of the tibial inserts, including the articular surface, backside surface, sides, and locking mechanism. No subsurface changes were found. The micro-CT results were a useful adjunct to gravimetric analysis, better defining the dimensional changes that occurred with testing and ruling out subsurface fatigue.
No preview · Article · Aug 2014 · The Journal of Arthroplasty
[Show abstract][Hide abstract] ABSTRACT: Increased modularity of total hip arthroplasty components has occurred, with theoretical advantages and disadvantages. Recent literature indicates the potential for elevated revision rates of modular neck systems and the potential for local pseudotumor and metallosis formation at the modular neck/stem site. Retrieval analysis of one modular neck implant design including SEM (Scanning Electron Microscopy) assessment was done and correlated to FEA (Finite Element Analysis) as well as clinical features of patient demographics, implant and laboratory analysis. Correlation of the consistent corrosion locations to FEA indicates that the material and design features of this system may result in a biomechanical reason for failure. The stem aspect of the modular neck/stem junction may be at particular risk.
No preview · Article · Jun 2014 · The Journal of Arthroplasty
[Show abstract][Hide abstract] ABSTRACT: The U.S. Food and Drug Administration has requested post-market surveillance data, including data on metal ion levels, regarding metal-on-metal total hip arthroplasty. We performed a prospective, randomized study of metal ion levels in erythrocytes, serum, and whole blood at five years after 28 and 36-mm metal-on-metal and 28-mm metal-on-polyethylene total hip arthroplasty.
One hundred and five enrolled patients were randomized equally to the three bearing surface options and were blinded with regard to their treatment group. Metal ion measurements and clinical evaluations were performed at regular intervals.
Cobalt and chromium ion levels in all blood sample types at the five-year time point were significantly lower in the metal-on-polyethylene group than in each of the two metal-on-metal groups (p < 0.001) with the exception of chromium in erythrocytes (p = 0.194). Cobalt in serum (p = 0.029) and erythrocytes (p = 0.002) showed significant increases from two to five years in the 36-mm metal-on-metal group; similar increases were not seen in the 28-mm metal-on-metal group. At five years, five patients in the 36-mm metal-on-metal group and none in the 28-mm metal-on-metal group had cobalt or chromium levels of >7 ppb. Correlations among levels in serum, erythrocyte, and whole blood were stronger for cobalt than for chromium. One patient in the 36-mm metal-on-metal group underwent revision because of an adverse local tissue reaction.
The 36-mm metal-on-metal bearing underperformed the 28-mm metal-on-metal bearing with respect to metal ion levels. The authors are closely following all patients treated with metal-on-metal total hip arthroplasty.
Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
No preview · Article · Mar 2014 · The Journal of Bone and Joint Surgery
[Show abstract][Hide abstract] ABSTRACT: A web-based followup assessment may be a feasible, cost-saving alternative of tracking patient outcomes after total joint arthroplasty. However, before implementing a web-based program, it is important to determine patient satisfaction levels with the new followup method. Satisfaction with the care received is becoming an increasingly important metric, and we do not know to what degree patients are satisfied with an approach to followup that does not involve an in-person visit with their surgeons.
We determined (1) patient satisfaction and (2) patients' preferences for followup method (web-based or in-person) after total joint arthroplasty.
We randomized patients who were at least 12 months after primary THA or TKA to complete a web-based followup or to have their appointment at the clinic. There were 410 eligible patients contacted for the study during the recruitment period. Of these, 256 agreed to participate, and a total of 229 patients completed the study (89% of those enrolled, 56% of those potentially eligible; 111 in the usual-care group, 118 in the web-based group). Their mean age was 69 years (range, 38-86 years). There was no crossover between groups. All 229 patients completed a satisfaction questionnaire at the time of their followup appointments. Patients in the web-based group also completed a satisfaction and preference questionnaire 1 year later. Only patients from the web-based group were asked to indicate preference as they had experienced the web-based and in-person followup methods. We used descriptive statistics to summarize the satisfaction questionnaires and compared results using Pearson's chi-square test.
Ninety-one patients (82.0%) in the usual-care group indicated that they were either extremely or very satisfied with the followup process compared with 90 patients (75.6%) who were in the web-based group (p < 0.01; odds ratio [OR] = 3.95; 95% CI, 1.79-8.76). Similarly, patients in the usual care group were more satisfied with the care they received from their surgeon, compared with patients in the web-based group (92.8% versus 73.9%; p < 0.01, OR = 1.37; 95% CI, 0.73-2.57). Forty-four percent of patients preferred the web-based method, 36% preferred the usual method, and 16% had no preference (p = 0.01).
Our results show moderate to high satisfaction levels with a web-based followup assessment. Patients who completed the usual method of in-person followup assessment reported greater satisfaction; however, the difference was small and may not outweigh the additional cost and time-saving benefits of the web-based followup method.
Level I, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.
No preview · Article · Feb 2014 · Clinical Orthopaedics and Related Research
[Show abstract][Hide abstract] ABSTRACT: Currently, there is a lack of high-level evidence addressing the variety of treatment options available for patients diagnosed with femoroacetabular impingement (FAI). The objective was to determine the current state of practice for FAI in Canada.
A questionnaire was developed and pretested to address the current state of knowledge among orthopaedic surgeons regarding FAI treatment using a focus group of experts, reviewing prior surveys, and reviewing online guidelines addressing surgical interventions for FAI. The membership of the Canadian Orthopaedic Association (COA) was surveyed through email and mail in both French and English.
Two hundred and two surveys were obtained (20 % response rate), of which 74.3 % of respondents manage patients under age 40 with hip pain. Most surgeons (62 %) considered failure of non-operative management as the most important indication for the surgical management of FAI, usually by treating both bony and soft tissue damage (54.4 %). The majority of surgeons were unsure of the existence of evidence supporting the best clinical test for FAI, the use of a diagnostic intra-articular injection for diagnosis of FAI, and for non-operative management of FAI. One in four respondents supported a sham surgery (24.8 %) control arm for a trial evaluating the impact of surgical intervention on FAI.
This survey elucidates areas of research for future studies relevant to FAI and highlights controversial areas of treatment. The results suggest that the current management of FAI by members of the COA is limited by a lack of awareness of high-level evidence. LEVEL OF EVIDENCE: III.
No preview · Article · Feb 2014 · Knee Surgery Sports Traumatology Arthroscopy