Matthew Kraay

First-generation highly crosslinked polyethylene (HXLPE) was developed to reduce polyethylene wear debris and subsequent osteolysis. Two thermal stabilization strategies were developed, annealing and remelting, to remove free radicals remaining in the polymer. Both types of HXLPEs have demonstrated better wear resistance to conventional polyethylene in hip arthroplasty. However, few studies have directly compared the mid- to long-term clinical outcomes of first-generation HXLPEs. We sought to address the following research questions: (1) is there a difference between the revision reasons for HXLPE formulations (annealed and remelted), (2) is there a difference in oxidation between annealed and remelted HXLPEs, (3) is there a difference in the linear penetration rate of annealed and remelted HXLPEs, and (4) does the formulation of first-generation HXLPEs affect the prevalence of osteolysis? A total of 129 first-generation HXLPE acetabular liners were collected in a multicenter retrie...

Readmission within 90 days following total joint arthroplasty has become a central quality measure of reimbursement initiatives; however, the validity of readmission rates as a measure of hospital care quality and the proportion of readmissions that are preventable are unknown. The purpose of this study is to determine if readmissions within 30 and 90 days after total knee arthroplasty (TKA) were related to orthopaedic or medical etiology and identify if these readmissions were preventable. We retrospectively reviewed 1,625 elective TKAs performed between 2011 and 2014 at our institution. Readmissions within 30 and 90 days were categorized into orthopaedic and medical etiologies and an expert research panel determined if readmissions were potentially preventable based on objective criteria from national or peer-reviewed consensus guidelines. Out of the 1,625 TKAs performed during the study period, there were a total of 79 (4.8%) readmissions within 90 days of surgery, of which 17 (2...

All polyethylene acetabular liners wear over time, and numerous methods for calculating linear wear rates exist. The objective of this study was to compare 2-dimensional wear rates between direct, micrometer measurements and the computerized, edge-detection method using Hip Analysis Suite (HAS) 8.0.4.3. Two groups of retrieved acetabular liners from Harris-Galante Prosthesis I and Harris-Galante Prosthesis II implants in situ for more than 10 years were evaluated. Group 1 (n = 18) contained liners with both early postoperative (<6 months) and prerevision radiographs taken within 1 month of explantation. Group 2 (n = 55) included liners with only prerevision X-rays (ie, 1 radiograph for wear assessment). Average and maximum direct linear wear was calculated from thicknesses measured at 6 consistent, well-separated locations (3 in the worn and 3 in the unworn regions) using a calibrated, digital micrometer. HAS 8.0.4.3 was used to calculate 2-dimensional wear from anteroposterior p...

Concerns have arisen regarding deterioration of wear properties of yttria-stabilized zirconia (YSZ) femoral head on conventional polyethylene (PE) bearings due to YSZ phase transformation. The purpose of this study was to determine if there is a difference in long-term PE wear properties between YSZ and cobalt-chromium-molybdenum (Co-Cr-Mo) femoral heads. Ten-year radiographic wear assessment was performed on a cohort of patients enrolled in a prospective randomized clinical trial comparing total hip arthroplasty with YSZ or Co-Cr-Mo femoral heads on conventional, non-cross-linked PE. PE linear wear, annualized wear, and steady-state wear rates remained low and similar between groups. No cases of osteolysis were observed. Measured conventional PE wear was similar between YSZ and Co-Cr-Mo femoral heads with the steady-state wear rates for both remaining below the generally accepted threshold at which osteolysis typically occurs. Whether clinically relevant phase transformation with Y...

During revision surgery with a well-fixed stem, a titanium sleeve can be used in conjunction with a ceramic head to achieve better stress distribution across the taper surface. In vitro testing suggests that corrosion is not a concern in sleeved ceramic heads; however, little is known about the in vivo fretting corrosion of the sleeves. The purpose of this study was to investigate fretting corrosion in sleeved ceramic heads in retrieved total hip arthroplasties. Thirty-seven sleeved ceramic heads were collected during revision. The femoral heads and sleeves were implanted 0.0-3.3 years. The implants were revised predominantly for instability, infection, and loosening. Fifty percent of the retrievals were implanted during a primary surgery. Fretting corrosion was assessed using the Goldberg-Higgs semiquantitative scoring system. Mild-to-moderate fretting corrosion scores (score = 2-3) were observed in 92% of internal tapers, 19% of external tapers, and 78% of the stems. Severe fretti...

Readmissions after total joint arthroplasty have become a key quality measure in elective surgery in the United States. The Affordable Care Act includes the Hospital Readmission Reduction Program, which calls for reduced payments to hospitals with excessive readmissions. This policy uses a method to determine excess readmission ratios and calculate readmission payment adjustments to hospitals, however, it is unclear whether readmission rates are an effective quality metric. The reasons or conditions associated with readmission after elective THA have been well established but the extent to which readmissions can be prevented after THA remains unclear. (1) Are unplanned readmissions after THA associated with orthopaedic or medical causes? (2) Are these readmissions preventable? (3) When during the course of aftercare are orthopaedic versus medical readmissions more likely to occur? We retrospectively evaluated all 1096 elective THAs for osteoarthritis performed between January 1, 2011 and June 30, 2014 at a major academic medical center. Of those, 69 patients (6%) who met inclusion criteria were readmitted in our healthcare system within 90 days of discharge after the index procedure during the study period. Fifty patients were readmitted within 30 days of discharge after the index procedure (5%). We defined a readmission as any unplanned inpatient or observation status admission to the hospital spanning at least one midnight. A panel of physicians not involved in the care of these patients used available criteria and existing consensus guidelines to evaluate the medical records, radiographs, and operative reports to identify whether the underlying reason for readmission was orthopaedic versus medical. They subsequently were classified as either nonpreventable or potentially preventable readmissions, based on any care that may have occurred during the index hospitalization. To make such determinations, consensus specialty society guidelines were used whenever possible for each readmission diagnosis. A total of 50 of 1096 patients (5% of those who underwent THA during the period in question) were readmitted within 30 days and 69 of 1096 (6%) were readmitted within 90 days of their index procedures. Thirty-one patients were readmitted for orthopaedic reasons (31/69; 45%) and 38 of 69 were readmitted for medical reasons (55%). Three readmissions (three of 69; 4%) were identified as potentially preventable. Of these potentially preventable readmissions, one was orthopaedic (hip dislocation) and two were medical. Thirty-day readmissions were more likely to be orthopaedic than 90-day readmissions (odds ratio, 4.06; 95% CI, 1.18-13.96; p = 0.026). Using a panel of expert reviewers, available existing criteria, and consensus methodology, it appears only a small percentage of readmissions after THA are potentially preventable. Orthopaedic readmissions occur earlier during the postoperative course. Currently, existing policies and readmission penalties may not serve as valuable external quality metrics. The readmission rates in our study may represent the threshold for expected readmission rates after THA. Future studies should enroll larger numbers of patients and have independent review panels in efforts to refine criteria for what constitutes preventable readmissions. Level III, therapeutic study.

Previous studies identified imprinting of the stem morphology onto the interior head bore, leading researchers to hypothesize an influence of taper topography on mechanically assisted crevice corrosion. The purpose of this study was to analyze whether microgrooved stem tapers result in greater fretting corrosion damage than smooth stem tapers. A matched cohort of 120 retrieved head-stem pairs from metal-on-polyethylene bearings was created controlling for implantation time, flexural rigidity, apparent length of engagement, and head size. There were 2 groups of 60 heads each, mated with either smooth or microgrooved stem tapers. A high-precision roundness machine was used to measure and categorize the surface morphology. Fretting corrosion damage at the head-neck junction was characterized using the Higgs-Goldberg scoring method. Fourteen of the most damaged heads were analyzed for the maximum depth of material loss and focused ion beam cross-sectioned to view oxide and base metal. Fretting corrosion damage was not different between the 2 cohorts at the femoral head (P = .14, Mann-Whitney) or stem tapers (P = .35). There was no difference in the maximum depths of material loss between the cohorts (P = .71). Cross-sectioning revealed contact damage, signs of micro-motion, and chromium-rich oxide layers in both cohorts. Microgroove imprinting did not appear to have a different effect on the fretting corrosion behavior. The results of this matched cohort retrieval study do not support the hypothesis that taper surfaces with microgrooved stems exhibit increased in vivo fretting corrosion damage or material release.

ABSTRACT Specialized surgical techniques and knee replacement technology have been developed specifically to address the complexities of revision total knee replacement. Prior to surgery, a thorough understanding of the mechanism of failure and evaluation for possible periprosthetic sepsis is essential in order to obtain a satisfactory result. Removal of well-fixed implants, management of bone loss, soft tissue deficiency and instability, and a strategy for obtaining stable fixation of a new implant all need to be considered during the pre-operative planning phase of surgery. A well-thought-out pre-operative plan will ensure that all the necessary equipment and implants are available at the time of surgery and that all factors contributing to failure of the knee replacement are addressed.

Degenerative problems of the hip in patients with childhood and adult onset neuromuscular disorders can be challenging to treat. Many orthopaedic surgeons are reluctant to recommend total hip replacement (THR) for patients with underlying neuromuscular disorders due to the perceived increased risks of dislocation, implant loosening, and lack of information about the functional outcomes and potential benefits of these procedures in these patients. Modular femoral components and alternative bearings which facilitate the use of large femoral heads, constrained acetabular components and perhaps more importantly, a better understanding about the complications and outcomes of THR in the patient with neuromuscular disorders, make this option viable. This paper will review the current literature and our experience with THR in the more frequently encountered neuromuscular disorders.

We evaluated the clinical and radiographic outcomes of 100 consecutive primary total hip arthroplasties in which a proximally coated anatomically designed femoral component was fixed without cement for the treatment of primary osteoarthritis. The minimum duration of follow-up was six years (average, 7.1 years). The eighty-eight patients who had the arthroplasties were followed prospectively with a standard clinical evaluation that involved use of the Harris hip score and a radiographic evaluation based on the criteria of the Hip Society. Bone ingrowth was evaluated with the method of Engh et al. The average age of the patients at the time of the operation was 62.6 years (range, thirty-nine to eighty-four years). Fifty-one patients were men and thirty-seven were women. The average preoperative Harris hip score was 48 points, with an average pain score of 15 points and an average function score of 26 points. Nonmechanical complications that necessitated a revision operation included o...

The purpose of this study was to characterize the prevalence of taper damage in modular TKA components. One hundred ninety-eight modular components were revised after 3.9±4.2 years of implantation. Modular components were evaluated for fretting corrosion using a semi-quantitative 4-point scoring system. Design features and patient information were assessed as predictors of fretting corrosion damage. Mild-to-severe fretting corrosion (score ≥2) was observed in 94/101 tapers on the modular femoral components and 90/97 tapers on the modular tibial components. Mixed alloy pairs (p=0.03), taper design (p<0.001), and component type (p=0.02) were associated with taper corrosion. The results from this study supported the hypothesis that there is taper corrosion in TKA. However the clinical implications remain unclear.

Evaluation and management of 4 challenging knee case scenarios were discussed in an interactive session with a moderator and 5 experts in knee reconstruction. Case-based discussion included total knee arthroplasty in the presence of femoral deformity, deficient patellar bone, and patella baja, and treatment of infected total knee arthroplasty.

PMMA beam specimens were tested in four-point bending to determine if' the bending strength of acrylic bone cement, as used in posterior spinal fusion, could be improved by metal-wire reinforcement. The result showed that the load-carrying capacities of 1-and 0.5-mm diam ...

PMMA beam specimens were tested in four-point bending to determine if' the bending strength of acrylic bone cement, as used in posterior spinal fusion, could be improved by metal-wire reinforcement. The result showed that the load-carrying capacities of 1-and 0.5-mm diam ...

Metal-on-metal (MOM) hip resurfacing has become an increasingly popular treatment for young, active patients with degenerative disease of the hip, as bearing surfaces with better wear properties are now available. One proposed advantage of resurfacing is its ability to be successfully revised to total hip arthroplasty (THA). In addition, radiographic parameters that may predict failure in hip resurfacing have yet to be clearly defined. Seven MOM resurfacing arthroplasties were converted to conventional THAs because of aseptic failure. Using Harris Hip Scores (HHS) and Short Form 12 (SF-12) questionnaire scores, we compared the clinical outcomes of these patients with those of patients who underwent uncomplicated MOM hip resurfacing. In addition, all revisions were radiographically evaluated. Mean follow-up periods were 51 months (revision group) and 43 months (control group). There was no significant difference between the 2 groups' HHS or SF-12 scores. There was no dislocation or aseptic loosening after conversion of any resurfacing arthroplasty. Valgus neck-shaft angle (P < .03) was associated with aseptic failure of MOM hip resurfacing. Conversion of aseptic failure of hip resurfacing to conventional THA leads to clinical outcomes similar to those of patients who undergo uncomplicated hip resurfacing. The orientation of the femur and the components placed play a large role in implant survival in hip resurfacing. More work needs to be done to further elucidate these radiographic parameters.

Radiographic measurements of the wear of total hip arthroplasty implants are indirect measurements based on radiographic determinations of the location of the femoral head relative to the acetabular component. Using the simplest case of zero wear, we assessed the reproducibility and accuracy of two software applications designed to quantify wear from clinical radiographs. After a cobalt-chromium head was glued into the polyethylene liner of a titanium shell, one cross-table lateral radiograph and three anteroposterior pelvic radiographs were made for twelve permutations of acetabular component angulation. The three anteroposterior radiographs differed only with regard to the cephalocaudal positioning of the prosthesis relative to the x-ray tube. To assess method reproducibility, each anteroposterior radiograph was assumed to be both the initial and the latest follow-up radiograph of a wear analysis. To assess method accuracy, each anteroposterior radiograph was paired in a wear analysis with each of the two anteroposterior radiographs made when the component was in the same angulation but at a different cephalocaudal position relative to the tube (one radiograph was the initial follow-up radiograph while the second was the latest follow-up radiograph). The analyses of reproducibility and accuracy were performed both with and without inclusion of the lateral radiograph made with the component in the same angulation. Both methods fared well in the reproducibility analyses, with mean linear and volumetric wear values of 0.00 to 0.07 mm and 0 to 24 mm(3), respectively. In the accuracy analyses, the mean linear and volumetric wear values derived with the two methods were 0.26 to 0.40 mm and 78 to 126 mm(3), respectively. Whereas the results of the reproducibility analyses showed that the methods were consistent in determining the relative positions of the head and shell from a given anteroposterior radiograph or pair of anteroposterior and lateral radiographs, the non-zero wear results obtained in the accuracy analyses proved that these positional determinations were often inaccurate. Thus, while contemporary software methods may yield reproducible results, their accuracy is limited by their inability to correctly determine the position of the head relative to the acetabular component.

The long term survival of the Miller-Galante I cementless total knee arthroplasty was evaluated by studying prospectively for a minimum of 14 years (range, 14-17 years), 124 consecutive cementless total knee arthroplasties using a Miller-Galante I prosthesis in 99 patients with a mean age of 62 years who had primary or secondary osteoarthritis. Knee function and roentgenograms were evaluated using the Knee Society criteria. Kaplan-Meier survivorship analysis was conducted. Five patients (five knees) were lost to followup; six patients died with six knees in place. Fifteen knees (15 patients) failed and were revised. Thirteen metal-backed patellas were revised. Eight of these revisions also required exchange of the femoral component, but only one tibial tray was revised. One knee (one patient) was revised for an infection. Of the 98 knees not revised (73 patients) observed throughout this study, the average preoperative knee score was 31 (range, 0-47); postoperatively, the average knee score was 91 (range, 72-100). The average function score improved from 28 (range, 10-45) to 84 (range, 50-100). Twenty-four tibial trays (21%) and twenty femoral components (17%) of the 113 knees studied showed osteolysis. This study indicates that osteointegration of cementless tibial components can be successful with screw fixation, although there is a worrisome incidence of tibial and femoral osteolysis. The overall knee survival rate was 87%; however, the tibial component had a survival of 99%.

Metal-on-metal (MOM) hip resurfacing has become an increasingly popular treatment for young, active patients with degenerative disease of the hip, as bearing surfaces with better wear properties are now available. One proposed advantage of resurfacing is its ability to be successfully revised to total hip arthroplasty (THA). In addition, radiographic parameters that may predict failure in hip resurfacing have yet to be clearly defined. Seven MOM resurfacing arthroplasties were converted to conventional THAs because of aseptic failure. Using Harris Hip Scores (HHS) and Short Form 12 (SF-12) questionnaire scores, we compared the clinical outcomes of these patients with those of patients who underwent uncomplicated MOM hip resurfacing. In addition, all revisions were radiographically evaluated. Mean follow-up periods were 51 months (revision group) and 43 months (control group). There was no significant difference between the 2 groups' HHS or SF-12 scores. There was no dislocation ...

Radiographic measurements of the wear of total hip arthroplasty implants are indirect measurements based on radiographic determinations of the location of the femoral head relative to the acetabular component. Using the simplest case of zero wear, we assessed the reproducibility and accuracy of two software applications designed to quantify wear from clinical radiographs. After a cobalt-chromium head was glued into the polyethylene liner of a titanium shell, one cross-table lateral radiograph and three anteroposterior pelvic radiographs were made for twelve permutations of acetabular component angulation. The three anteroposterior radiographs differed only with regard to the cephalocaudal positioning of the prosthesis relative to the x-ray tube. To assess method reproducibility, each anteroposterior radiograph was assumed to be both the initial and the latest follow-up radiograph of a wear analysis. To assess method accuracy, each anteroposterior radiograph was paired in a wear anal...

Wear of the ultra-high molecular weight polyethylene articular surface has been recognized as a major factor threatening the long-term success of total hip arthroplasty. Manual techniques that have been used to measure femoral head penetration into the polyethylene have been plagued with poor reproducibility and limited accuracy. Using a previously described phantom model simulating an unworn total hip arthroplasty, we previously demonstrated significant limitations in the accuracy of several widely used computerized wear measurement programs. A major component of these inaccuracies is projectional distortion of the femoral head and acetabular shell on the radiograph. These inaccuracies can be "corrected for" mathematically. In the present follow-up study, we evaluated a widely used hip wear measurement software program (Hip Analysis Suite version 8.0.3.0) that corrects for these projectional errors with use of our previously described "zero wear" phantom model. ...

Carbon fiber-reinforced ultra-high molecular weight polyethylene (Poly II) was clinically introduced in the 1970s, but catastrophic short-term outcomes were reported in case studies. Clinical use of Poly II persisted into the 1980s until it was eventually abandoned. To date, no studies have documented its long-term clinical and material performance. Forty Poly II tibial inserts of the Total Condylar, Insall-Burstein I, and Miller-Galante I designs were retrieved at revision surgery. Twenty-six historical unreinforced polyethylene knee retrievals of similar designs (Miller-Galante I and II, and Insall-Burstein II) served as the control group. The average in vivo durations of both retrieval groups were similar (11.1 and 11.6 years, respectively), although Poly II had a wider implantation range (3.7-32.8 years) than historical polyethylene (4.4-17.0 years). Surface damage on all the retrievals, as well as oxidation and mechanical strength when possible, were characterized. Poly II tibial inserts had long-term clinical survivability and material performance comparable to unreinforced polyethylene bearings. Poly II retrievals exhibited less surface damage at all the regions than historical components, and they were less sensitive to pitting and delamination, but more susceptible to abrasion and embedded debris. Both Poly II and historical retrievals were found to oxidize in vivo and exhibited similar mechanical strength. This study provides improved understanding of well-consolidated Poly II long-term retrievals and also motivation to revisit carbon fiber-reinforced polymeric bearings for joint replacement in the twenty-first century.

Screening vascular ultrasonography was performed postoperatively on 164 consecutive patients being treated with total knee arthroplasty (203 total knee prostheses). This consisted of examination of the femoral and popliteal veins of the operative extremity with color flow and duplex ultrasonography one week postoperatively. All patients received deep venous thrombosis (DVT) prophylaxis with sequential compressive pneumatic stockings, low-dose warfarin, continuous passive motion, and early mobilization. All patients were observed prospectively for thromboembolic sequelae for a minimum of six months postoperatively. The screening study was significantly limited in six (3%) of the 203 total knee prostheses. The overall incidence of sonographically detected proximal DVT or symptomatic calf vein thrombosis was 3% (6/203), and the incidence of symptomatic pulmonary embolism was 2% (4/203). Four of the ten thromboembolic complications occurred after hospital discharge. Results of this study suggest that duplex ultrasonography can be a useful screening method for identification of venous thrombosis after TKA. Patients with asymptomatic proximal DVT can be identified and appropriately treated before development of serious thromboembolic complications. Routine screening for DVT after TKA can avoid the considerable expense, inconvenience, and potential risk of complications associated with prolonged postoperative prophylactic anticoagulation. The combination of sequential compressive stockings, early mobilization, and low-dose warfarin appears to be a safe and effective prophylactic regimen against venous thromboembolic disease in these high-risk patients.