Clinical Outcomes of Isolated Polyethylene Exchange Versus Full Component Revision for the Management of Instability Following Total Knee Arthroplasty.

BACKGROUND: Instability following total knee arthroplasty (TKA) is a common cause for revision. Isolated polyethylene exchange (IPE) can be performed to increase knee joint stability, but results have been mixed. The purpose of this study was to compare the survivorship and patient-reported outcomes of patients undergoing revision TKA for instability with IPE versus full component revision. METHODS: We reviewed 280 primary TKAs undergoing revision TKA for instability. There were 181 knees that underwent revision with IPE, compared to 99 knees treated with full component revision. The mean follow-up was 32.8 months (range, 24.8 to 82.5). Patient demographics, radiographic parameters, prosthesis constraints, reoperations for instability, and patient-reported outcomes were compared. RESULTS: The survivorship for instability was significantly higher at 2 years (99 versus 92%, P = .024) and 5 years (94 versus 84%, P = .024) for patients undergoing full component revision. Although there was no difference in Knee Injury and Osteoarthritis Outcome Score for Joint Replacements and Veterans RAND 12 physical component scores between the 2 groups at 6 weeks, 1 year, and 2 years after surgery, full revision patients reported greater pain relief (P = .006) and greater improvements in Veterans RAND 12 physical component scores (P = .027) at 1 year and Knee Injury and Osteoarthritis Outcome Score for Joint Replacements scores at 2 years (P = .017) compared to IPE patients. Men were associated with an increased risk for recurrent instability following IPE (hazard ratio 3.3, 95% confidence interval: [1.0 to 10.6]). CONCLUSIONS: Isolated polyethylene exchange was not as reliable or durable compared to full component revision for the management of postoperative instability. These procedures should only be reserved in cases with competent collaterals and when component position, offset, and rotation are optimized.

Fretting Corrosion, Third-Body Polyethylene Damage, and Cup Positioning in Primary vs Revision Dual Mobility Total Hip Arthroplasty.

BACKGROUND: Dual mobility (DM) articulations were introduced for total hip arthroplasty to reduce the risk of instability for patients who have a high risk of dislocation. The use of DM constructs in both primary and revision total hip arthroplasty has been steadily increasing, leading to concerns regarding potential risks of fretting corrosion, polyethylene wear, metal release, and failure due to component positioning. METHODS: A total of 56 retrieved DM constructs were collected. The inner and outer polyethylene liner surfaces were assessed for 7 damage mechanisms, and fretting corrosion was evaluated for the femoral stem, head, and modular liner. Three polyethylene liners with the greatest amounts of embedded debris were examined using scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to determine the elemental content of the debris. Acetabular cup orientation was analyzed radiographically using the EBRA (Einzel-Bild-Roentgen-Analyse) method. RESULTS: The devices were revised most frequently for infection (36%), loosening (21%), and instability/dislocation (18%). The most common polyethylene damage mechanisms were scratching, pitting, burnishing, and embedded debris, and no difference in total damage was found between primary and revision cases. Scanning electron microscopy/energy-dispersive X-ray spectroscopy revealed that debris morphology and composition were consistent with porous titanium coating, resulting from cup loosening or broken screws and augments. A total of 71% and 50% of the constructs were determined to be within the Lewinnek safe zone for inclination and anteversion, respectively. CONCLUSION: The most notable mechanisms of surface damage were due to third-body debris, especially for the polyethylene surfaces which articulate against cobalt-chromium femoral heads and acetabular liners. Scratching of the femoral head and the metal liner from this debris may support the clinical use of ceramic for DM bearing surfaces in the future.

Reasons for Revision, Oxidation, and Damage Mechanisms of Retrieved Vitamin E-Stabilized Highly Crosslinked Polyethylene in Total Knee Arthroplasty.

BACKGROUND: In order to improve oxidation resistance, antioxidants such as vitamin-E are added to polyethylene used in the bearing surfaces of orthopedic components. Currently, little is known about the efficacy of this treatment in vivo. This study therefore reports on the reasons for revision, surface damage mechanisms, and oxidation of retrieved vitamin E-stabilized highly crosslinked polyethylene (HXLPE) for total knee arthroplasty. METHODS: We examined 103 retrieved knee inserts fabricated from vitamin E (VE)-stabilized HXLPE and 67 fabricated from remelted HXLPE as a control. The implantation times were 1.2 ± 1.3 and 1.5 ± 1.3 years for the VE and control cohorts, respectively. The inserts were evaluated for 7 surface damage mechanisms using a semiquantitative scoring method and analyzed for oxidation using Fourier-transform infrared spectroscopy. Reasons for revision were also assessed using operative notes created at time of retrieval. RESULTS: Both groups were revised primarily for instability, infection, and loosening. Burnishing, pitting, and scratching were the most common damage mechanisms observed, with the VE cohort demonstrating less surface damage than the control. Measured oxidation for the cohort was low, with a median oxidation index of 0.09 ± .05 for the articulating surface, 0.05 ± 0.06 for the backside, 0.08 ± 0.06 for the anterior/posterior surfaces, and 0.08 ± 0.05 for the stabilizing post. As compared to the control cohort, oxidation tended to be less for the VE group at the articulating (P < .001) and backside (P = .003) surfaces, although the median differences were minimal and may not be clinically significant. CONCLUSION: The results indicate positive fatigue damage resistance and oxidation resistance for the retrieved VE-stabilized total knee arthroplasty inserts.

Midterm Clinical and Radiographic Results of Mobile-Bearing Revision Total Knee Arthroplasty.

BACKGROUND: Constrained implants are frequently required in revision total knee arthroplasty (TKA) and are associated with an increase in aseptic component loosening and damage or wear to the constraining mechanisms, compared with primary TKA. The purpose of the following study was to evaluate the midterm clinical and radiographic results including the incidence of bearing complications in a group of patients undergoing revision TKA using mobile-bearing revision TKA implants. METHODS: We retrospectively reviewed 316 consecutive mobile-bearing revision TKAs performed at 2 centers between 2006 and 2010. There were 183 women and 133 men with a mean age of 66 years. The patients were evaluated clinically using the Knee Society scores. A radiographic analysis was performed. Bearing specific complications (ie, instability or dislocation) were recorded. RESULTS: Patients were followed-up for a minimum of 24 months and a median of 59.88 months (range 24-121.2). The average Knee Society knee score and function scores increased from 40.8 and 47.9 points preoperatively to 80 points and 70.3 points, respectively (P < .01). The average knee flexion improved from 105.6° preoperatively to 117.4° postoperatively (P < .01). Eight patients required subsequent implant revision. No cases of bearing complications were observed. CONCLUSION: Revision TKA using mobile-bearing revision components demonstrated favorable midterm clinical and radiographic results with no occurrence of bearing instability or dislocation. Longer follow-up is required to evaluate for potential advantages of mobile-bearings over fixed-bearing revision components in terms of polyethylene wear reduction, reduced stress transmission across fixation interfaces, and reduced stress on the polyethylene post.

Fretting and Corrosion Damage in Taper Adapter Sleeves for Ceramic Heads: A Retrieval Study.

BACKGROUND: 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. METHODS: 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. RESULTS: 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 fretting corrosion was observed in 1 stem trunnion that was previously retained during revision surgery and none of the retrieved sleeves. There was no difference in corrosion damage of sleeves used in primary or revision surgery. CONCLUSION: The fretting corrosion scores in this study were predominantly mild and lower than reported fretting scores of cobalt-chrome heads in metal-on-polyethylene bearings. Although intended for use in revisions, we found that the short-term in vivo corrosion behavior of the sleeves was similar in both primary and revision surgery applications. From an in vivo corrosion perspective, sleeves are a reasonable solution for restoring the stem taper during revision surgery.

Do Stem Taper Microgrooves Influence Taper Corrosion in Total Hip Arthroplasty? A Matched Cohort Retrieval Study.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Polyethylene Liner Dissociation Is a Complication of the DePuy Pinnacle Cup: A Report of 23 Cases.

BACKGROUND: Polyethylene liner dissociation is a rare but catastrophic event in total hip arthroplasty (THA), and certain implant designs are known to be at greater risk. Although the DePuy Pinnacle (Warsaw, IN, USA) modular acetabular construct has an excellent record of fixation and wear, an unexpectedly high number of liner dissociations has been noted. QUESTIONS/PURPOSES: The purposes of this study were (1) to characterize the clinical parameters observed in a large group of patients who have experienced liner dissociations with the DePuy Pinnacle acetabular component; (2) to describe the radiographic findings in this group of patients; and (3) to calculate a minimum frequency of this complication. METHODS: Since 2001, 23 patients with previously well-functioning THAs presented with sudden atraumatic polyethylene liner dissociation at four separate institutions. These THAs were performed between 2001 and 2013. Eight different arthroplasty specialists had performed the index hip arthroplasties using the DePuy Pinnacle acetabular component with a polyethylene liner. Polyethylene failures were evaluated for liner type and radiographic cup position. For three of the surgeons who contributed cases, institutional registries allowed the calculation of the number of components of this type that they used during the period in question, which provided a conservative estimate of the frequency of this type of failure. RESULTS: All 23 liner failures occurred atraumatically in previously asymptomatic THAs at a mean of 48 months (range, 3-138 months). Patients characteristically reported a new and sudden onset of discomfort with audible, reproducible squeaking. Surgical inspection of dissociated liners demonstrated displacement of polyethylene with shearing of the peripheral locking tabs. Radiographic evaluation demonstrated that 14 cups were well positioned and nine cups were malpositioned outside the so-called safe zone. Conservative estimates of the frequency of this complication from the three surgeons' practices whose institutional registries allowed calculation of the lowest possible frequency were 0.32% (six of 1888), 0.77% (three of 391), and 0.82% (three of 367). CONCLUSIONS: With this report of 23 additional liner dissociations, we suggest that surgeons should be aware of the problem and take extra precautions when using this implant to ensure locking mechanism integrity at the time of surgery. We caution that the frequency of liner dissociation may be higher than previously reported. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Outcomes of long tapered hydroxyapatite-coated stems in revision total hip arthroplasty.

The purpose of this study was to evaluate the outcome of femoral component revisions using a long tapered HA coated femoral revision stem. Between 2001 and 2008, 55 femoral component revisions were performed using this stem. Forty-one patients were available for follow up evaluation at average of 59 months. The clinical results were evaluated using the HHS and serial radiographs were evaluated for loosening. The mean HHS was 71 (range 22-100). Three hips required revision of KAR stem (1 aseptic loosening, 1 infection, 1 limb length discrepancy). Only one prosthesis demonstrated radiographic evidence of subsidence. Our study suggests that long tapered HA coated revision femoral components can provide stable fixation and in-growth in cases where there is good proximal femoral bone stock and favorable canal geometry.

Mechanically assisted taper corrosion in modular TKA.

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.

Do ceramic femoral heads reduce taper fretting corrosion in hip arthroplasty? A retrieval study.

BACKGROUND: Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads. QUESTIONS/PURPOSES: We asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads. METHODS: One hundred femoral head-stem pairs were analyzed for evidence of fretting and corrosion using a visual scoring technique based on the severity and extent of fretting and corrosion damage observed at the taper. A matched cohort design was used in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design, and flexural rigidity. RESULTS: Fretting and corrosion scores were lower for the stems in the ceramic head cohort (p=0.03). Stem alloy (p=0.004) and lower stem flexural rigidity (Spearman's rho=-0.32, p=0.02) predicted stem fretting and corrosion damage in the ceramic head cohort but not in the metal head cohort. The mechanism of mechanically assisted crevice corrosion was similar in both cohorts although in the case of ceramic femoral heads, only one of the two surfaces (the male metal taper) engaged in the oxide abrasion and repassivation process. CONCLUSIONS: The results suggest that by using a ceramic femoral head, CoCr fretting and corrosion from the modular head-neck taper may be mitigated but not eliminated. CLINICAL RELEVANCE: The findings of this study support further study of the role of ceramic heads in potentially reducing femoral taper corrosion.

Prospective results of uncemented tantalum monoblock tibia in total knee arthroplasty: minimum 5-year follow-up in patients younger than 55 years.

A significant increase in younger patients undergoing total knee arthroplasty raises the theoretical concern for revision secondary to micromotion and fixation failure with cemented components. We prospectively studied 100 consecutive tantalum monoblock uncemented tibial components and 312 concurrent cemented controls. Patients younger than 55 years with adequate bone stock were enrolled. This cementless patient group was younger and had higher preoperative functional status. Prostheses were posterior-substituting uncemented femoral and tibial components with a cemented patellar button. Knee Society pain and function scores and radiographs were obtained, and a cost analysis was performed. Knee Society scores were excellent and equivalent beyond 6 months. There was no significant difference in perioperative blood loss, complication rates, or cost. There was a significant decrease in operative time in the uncemented group. Radiographs revealed no failures of ingrowth at last follow-up. There were 3 uncemented group failures, but none were due to failure of fixation. The use of a porous tantalum tibia at minimum 5 years has yielded promising clinical and radiographic results in a younger patient population.

Does Metal Transfer Differ on Retrieved Ceramic and CoCr Femoral Heads?

Metal transfer has been observed on retrieved THA femoral heads for both CoCr and ceramic bearing materials. In vitro wear testing has shown increased wear to polyethylene acetabular liners with the presence of metal transfer. This study sought to investigate the extent of metal transfer on the bearing surface of CoCr and ceramic femoral heads and identify prevalent morphologies. Three bearing couple cohorts: M-PE (n = 50), C-PE (n = 35), and C-C (n = 15), were derived from two previously matched collections (n = 50/group) of CoCr and ceramic femoral heads. From the three cohorts, 75% of the femoral heads showed visual evidence of metal transfer. These femoral heads were analyzed using direct measurement, digital photogrammetry, and white light interferometry. Surface area coverage and curved median surface area were similar among the three cohorts. The most prevalent metal transfer patterns observed were random stripes (n = 21/75), longitudinal stripes (n = 17/75), and random patches (n = 13/75). Metal transfer arc length was shorter in the M-PE cohort. Understanding the morphology of metal transfer may be useful for more realistic recreation of metal transfer in in vitro pin-on-disk and joint simulators studies.

Ceramic-on-ceramic total hip arthroplasty in patients younger than 55 years.

PURPOSE: To review the outcomes of 65 patients younger than 55 years who underwent uncemented total hip arthroplasty (THA) using third-generation ceramic-on-ceramic prostheses. METHODS: Medical records of 30 men and 35 women (80 hips) aged 18 to 55 (mean, 39) years who underwent uncemented THA using third-generation ceramic-onceramic prostheses by a single surgeon were reviewed. 61 THAs used the Reflection cup with the Synergy stem (n=49), Spectron stem (n=7), or Anthology stem (n=5), and 19 THAs used the Trident cup with the Secur-Fit stem. Outcomes were assessed based on the UCLA Activity Score and Harris Hip Score, as well as radiolucency around the implants, malposition, and subsidence on radiographs. Patients were asked about their satisfaction with current activity level (yes/no), activity limitation (no limitation, musculoskeletal limitation, psychological impediments and lack of motivation, and pain or disability of the operative hip), and change in occupational activity level (same or similar, more active, and less active or disability). RESULTS: The mean follow-up period was 54 (range, 24-110) months. Six patients were excluded from the analysis owing to prosthetic failure secondary to ceramic liner fracture after falling (n=2), acetabular component loosening (n=1), intolerable squeak (n=1), periprosthetic fracture (n=1), and instability (n=1). The mean UCLA Activity Score improved from 4.0 (range, 1-10) to 7.7 (range, 2-10) [p<0.001], and the mean Harris Hip Score improved from 52.8 (range, 25-69) to 91.0 (range, 38-100) [p<0.001]. No hip had evidence of subsidence, loosening, or osteolysis. 52 (80%) patients were satisfied with their activity level; 28 (43%) patients reported no activity limitation; and 57 (88%) patients kept the same or similar occupation. CONCLUSION: Ceramic-on-ceramic THA achieved acceptable clinical and radiographic outcomes.

Spontaneous dissociation of offset, face-changing polyethylene liners from the acetabular shell: a report of four cases.

BACKGROUND: Dissociation of the polyethylene liner from the acetabular shell is an uncommon event. Offset, face-changing polyethylene liners theoretically increase femoral head coverage, allow for larger heads with smaller cup diameters, and offer improved stability without risk of impingement. However, we present four cases of liner dissociations from the acetabular shell that necessitated revision hip surgery. METHODS: Four patients with spontaneous dissociations of offset, face-changing polyethylene acetabular liners underwent revision hip arthroplasty between January 2007 and June 2010. All patients were women with an average age of fifty-three years. All cases involved the combination of a Pinnacle acetabular component with an offset, face-changing polyethylene liner. We reviewed the presenting signs and symptoms associated with liner dissociations and analyzed the radiographs for the acetabular component position. RESULTS: All cases of liner dissociation occurred without direct trauma and were associated with squeaking sounds reported by the patient. The average cup abduction angle was 55° (range, 51° to 60°) and the average anteversion was 21.5° (range, 17° to 24°). Examination of the dissociated liners at the time of revision surgery revealed plastic deformation of the polyethylene liner rim posterosuperiorly at the eleven o'clock position on the right hip and the one o'clock position on the left hip. CONCLUSIONS: The combination of a vertically positioned acetabular component and an offset, face-changing liner resulted in impingement and dissociation of the liner from the shell in four patients. Proper acetabular component positioning, rather than the routine use of uniquely designed polyethylene liners, is critical to maximizing implant stability in total hip arthroplasty.

Total knee arthroplasty after prior bone or joint sepsis about the knee.

The current study was done to determine the effect of current methods to diagnose and treat infection on the incidence of deep prosthetic infection after total knee arthroplasty for patients with previous sepsis or osteomyelitis about the knee. Between 1989 and 1999, one surgeon did 20 consecutive primary total knee arthroplasties in 19 patients with a previous history of either septic arthritis or osteomyelitis about the knee. Antibiotic-impregnated cement was used in all patients. One patient was lost to followup and two patients died before 2 years from the arthroplasty. The remaining 16 patients were followed up for an average of 5 years (range, 2-11 years). There was one (5%) recurrent deep periprosthetic infection for which the patient required resection arthroplasty at 3.5 years. No patients required chronic antibiotic suppression. With careful preoperative and intraoperative evaluation and the routine use of antibiotic bone cement for fixation, total knee arthroplasty, in patients with prior bone or joint sepsis about the knee can provide good pain relief, functional improvement, and an acceptably low rate of deep prosthetic infection.

Systemic safety of high-dose antibiotic-loaded cement spacers after resection of an infected total knee arthroplasty.

The purpose of this study was to assess the systemic safety and potential adverse effects of using a high-dose antibiotic-impregnated cement spacer after resection arthroplasty of an infected total knee replacement. Between October 2000 and December 2002, 36 knees (34 patients) had a resection arthroplasty of an infected total knee prosthesis with placement of a high-dose antibiotic impregnated cement spacer. There were 24 men and 10 women with a mean age of 66.5 years (range, 48-84 years). All spacers placed contained an average of 3.4 batches of cement with an average total dose of 10.5 g of vancomycin (range, 3-16 g) and 12.5 g of gentamicin (range, 3.6-19.2 g). All patients were followed up post-operatively until reimplantation for evidence of renal failure. The preoperative creatinine ranged from 0.7 to 1.8 mg/dL. All patients were concomitantly treated with 6 weeks of intravenous organism-specific antibiotics. One patient with normal preoperative renal function (Cr 0.7 mg/dL) had a perioperative 1-day transient rise in serum creatinine (1.7 mg/dL) postoperatively that subsequently normalized. No patients showed any clinical evidence of acute renal insufficiency, failure, or other systemic side effects of the antibiotics. Treatment of patients with an infected total knee arthroplasty with high-dose vancomycin and gentamicin antibiotic spacers seems to be clinically safe.