Subsidence remains a concern when utilizing modern tapered fluted titanium (TFT) femoral stems and may lead to leg length discrepancy, impingement, instability and failure to obtain stem osseointegration. This study aims to compare stem subsidence across three modern TFT stems. Our secondary aim was to investigate the influence of bicortical contact or ‘scratch fit’ on subsidence, as well as the role of intraoperative imaging in maximizing this bicortical contact and preventing stem subsidence. A retrospective review of 271 hip arthroplasties utilizing modern TFT stems in a single institution was performed. Three stem designs were included in the analysis: one monoblock TFT stem (n=91) and two modular TFT stems (Modular A [n=90]; Modular B [n=90]). Patient demographics, Paprosky femoral bone loss classification, bi-cortical contact, utilization of intra-operative imaging and stem subsidence (comparison of initial post-operative radiograph to the latest follow up radiograph - minimum three months) were recorded. There was no statistically significant difference in the amount of subsidence between the three stems (Monoblock: 2.33mm, Modular A: 3.43mm, Modular B: 3.02mm; p=0.191). There was no statistical difference in subsidence >5mm between stems (Monoblock: 9.9%, Modular A: 22.2%, Modular B: 16.7%). Subgroup analysis based on femoral bone loss grading showed no difference in subsidence between stems. Increased bicortical contact was strongly associated with reduced subsidence (p=0.004). Intra-operative imaging was used in 46.5% (126/271) of cases; this was not correlated with bicortical contact (p=0.673) or subsidence (p=0.521). Across all groups, only two stems were revised for subsidence (0.7%). All three modern TFT stems were highly successful and associated with low rates of subsidence, regardless of modular or monoblock design. Surgeons should select the stem that they feel is most clinically appropriate.
The purpose of this study was to precisely measure the 10-year polyethylene wear rate of primary total hips using Radiostereometric analysis (RSA) comparing Oxidized Zirconium (OxZi) to cobalt chrome (CoCr) femoral heads articulating with highly cross-linked polyethylene (XLPE). RSA was performed on 46 patients who underwent total hip arthroplasty − 23 who received OxZi femoral heads and 23 who received CoCr heads in combination with XLPE at a minimum of 10 years follow-up. All patients had identical THR systems implanted except for the femoral head utilized. The Centre Index method was utilised to assess total wear rates (from index surgery until final evaluation) using a dedicated RSA Software program (UmRSA Digital Measure v.2.2.1). In addition, the Martell technique was used to subtract head penetration occurring in the first 1–2 years (i.e. bedding-in phase) to allow calculation of the ‘steady state’ wear rates. There were no significant differences in demographics (i.e age, BMI, gender) between the groups. The average time from surgery of the RSA examinations was 11.7 and 12.6 years for the CoCr and OxZi groups respectively. Using the Centre Index Method to calculate total head penetration, wear rates were slightly higher in the OxZi group (0.048 +/− 0.021mm/year) compared to the CoCr group (0.035 +/− 0.017mm/year) with no statistical difference between the groups (p= 0.02). After correction for the bedding-in period, there was no statistically significant difference in mean ‘steady-state’ wear rate between OxZi (0.031 +/− 0.021mm/year) and CoCr (0.024 +/− 0.019mm/year) at 10 year follow up (p= 0.24). A comparison of preoperative and postoperative SF12, HHS, and WOMAC scores showed no statistical difference between the groups. RSA demonstrated the 10 year in-vivo wear rates of both bearing combinations to be well below the threshold for osteolysis. There was no significant difference between either the total or ‘steady-state’ wear rates of the OxZi and CoCr groups at 10 years.
HXLPE acetabular liners were introduced to reduce wear-related complications in THA. However, post-irradiation thermal free radical stabilization can compromise mechanical properties, leave oxidation-prone residual free radicals, or both. Reports of mechanical failure of HXLPE acetabular liner rims raise concerns about thermal free radical stabilization and Remelted, single annealed and sequentially annealed retrieved HXLPE acetabular liners with Introduction
Material and Methods
Despite improvements in the survivorship of total knee replacements (TKR) over the years, patient satisfaction following TKR has not improved, with approximately 20% of patients recording dissatisfaction with their new knee joint. It is unclear why many patients feel this way, but it may relate in part to implant designs that do not provide a “natural” feeling knee. Implant manufacturers continue to introduce new concepts for implant design, which are essential for reaching the goal of a “normal” knee after TKR surgery. The Journey II TKR (Smith & Nephew) was developed with this goal in mind. Its anatomical design attempts to mimic the normal knee joint structure to return more natural kinematics to the joint, with emphasis on eliminating both paradoxical anterior motion and reduced posterior femoral rollback. Our objective is to examine patients receiving the Journey II TKR to measure the knee joint contact kinematics of the Journey II TKR compared to a non-anatomically designed implant by the same manufacturer. We hypothesize that the Journey II TKR will have more natural contact kinematics that differ from the non-anatomically designed implant. A total of 28 individuals were recruited to receive a Journey II TKR, matching an existing prior cohort with a non-anatomical design from the same manufacturer (Legion TKR, Smith & Nephew). For both groups, a series of radiostereometric analysis (RSA) images were acquired at different knee flexion angles, ranging in 20° increments from 0° to 120°. Model-based RSA software (RSACore, Leiden, Netherlands) was used to obtain the 3D positions and orientations of the femoral and tibial implant components, which were in turn used to obtain kinematic measures (contact locations and magnitude of excursion) for each condyle. Results from the Journey II TKR group at 3 months post-operation were compared to the 2-year post-operative measurements from the Legion TKR group.Introduction
Methods
The infection rate after total joint arthroplasty (TJA) has been shown to be 1–2% in multiple series and registry data. Irrigation, debridement, and polyethylene exchange (IDPE) is a common first line treatment in many cases of acute prosthetic joint infection (PJI). The reinfection rate in open IDPE procedures is variable with studies showing reinfection rates of 10–70% depending on various patient and microbial factors. Our pilot study aimed to determine if the bacterial load in infected total joints was sufficiently reduced by IDPE to allow for the use of post-debridement cultures as an independent marker of procedural success. 46 prosthetic joint infections underwent irrigation and debridement using 6L of normal saline and 3L of a normal saline and bacitracin mixture prior to the insertion of a new polyethylene liner. This protocol utilized a single equipment setup with all surgical members donning new gloves prior to polyethylene exchange. Between 3 and 5 intraoperative cultures were obtained both prior to and after debridement as per the surgeon's standard protocol. A two-tailed student's t-test was used to evaluate for any differences in the rate of positive culture between these two groups. Of all pre- and post-debridement cultures sampled 66.5% and 60.7% of cultures were positive respectively. No significant difference in the rate of positive intraoperative culture was found between pre-debridement and post-debridement groups (p = 0.52). In 32 of 46 (69%) cases there was no difference in the total number of positive cultures despite a thorough debridement. Our data shows that open debridement of PJI does not provide a sterile environment, and post-debridement cultures should not be used as an independent marker of procedural success. The role of an irrigation and debridement to reduce the bacterial burden and potentiate the clearance of an infection is established but its efficacy is unclear, and the inability to create a post-debridement sterile environment is a concern.
The purpose of this study is to compare 90-day costs and outcomes for primary total hip arthroplasty (THA) patients between a non-obese (BMI 18.5–24.9) versus overweight (25–29.9), obese (30–34.9), severely-obese (35–39.9), morbidly-obese (40–44.9), and super-obese (45+) cohorts. We conducted a retrospective review of a prospective institutional database of primary THA patients from 2006–2013, including patients with a minimum of three-year follow-up. Thirty-three super-obese patients were identified, and the other five cohorts were randomly selected in a 2:1 ratio (total n = 363). Demographics, 90-day outcomes (costs, reoperations, and readmissions), and outcomes after three years (revisions and change scores for SF12, HHS, and WOMAC) were collected. Costs were determined using unit costs from our institutional administrative data for all in-hospital resource utilization. Comparisons between the non-obese and other groups were made with Kruskal-Wallis tests for non-normal data and chi-square and Fisher's exact test for categorical data. The 90-day costs in the morbidly-obese ($13,134 ± 7,250 mean ± standard deviation, p <0.01) and super-obese ($15,604 ± 6,783, p <0.01) cohorts were statistically significantly greater than the non-obese cohorts ($10,315 ± 1,848). Only the super-obese cohort had statistically greater 90-day reoperation and readmission rates than the non-obese cohort (18.2% vs 0%, p <0.01 and 21.2% vs 4.5%, p=0.02, respectively). In addition, reoperations and septic revisions after 3 years were greater in the super-obese cohort compared to the non-obese cohort 21.2% vs 3.0% (p = 0.01), and 18.2% vs 1.5% (p= 0.01), respectively. There were no other statistical differences between the other cohorts with the non-obese cohort at 90-days or after 3 years. Improvements in SF12, HHS, and WOMAC were comparable in all cohorts. The 90-day costs of a primary total hip arthroplasty for morbidly-obese (BMI 40–44.9) and super-obese (BMI>45) are significantly greater than for non-obese patients, yet these patients have comparable improvements in outcome scores. Health care policies, when based purely on the economic impact of health care delivery, may place morbidly-obese and super-obese patients at risk of losing arthroplasty care, thereby denying them access to the comparable quality of life improvements.
Lewinnek's safe zone recommendation to minimise dislocations was a target of 5–25° for anteversion angle and 30–50° for inclination angle. Subsequently, it was demonstrated that mal-positioning of the acetabular cup can also lead to edge loading, liner fracture, and greater conventional polyethylene wear. The purpose of this study was to measure the effect of acetabular cup position on highly crosslinked polyethylene wear in total hip arthroplasty (THA) at long-term follow-up. We identified all patients that underwent primary THA with a minimum of 10 years follow-up using an institutional database in London, Ontario, Canada. Patients with a single implant design consisting of a 28 mm cobalt chromium head and highly crosslinked polyethylene liner (ram extruded, GUR 1050, 100 kGy gamma irradiated, remelted, ethylene oxide sterilised) were selected for inclusion. In total, 85 hips from 79 recruited patients were analysed. Patients underwent a supine radiostereometric analysis (RSA) exam in which the x-ray sources and detectors were positioned to obtain an anterior-posterior and cross-table lateral radiograph. Acetabular cup anteversion angle, inclination angle, and 3D penetration rate (including wear and creep) were measured from the stereo radiograph pairs. At a mean follow-up of 13 years (range, 10–17 years) the mean penetration rate was 0.059 mm/year (95% CI: 0.045 to 0.073 mm/year). Mean anteversion angle was 18.2° (range, −14 to 40°) and mean inclination angle was 43.6° (range, 27 to 61°). With respect to the Lewinnek safe zone, 67% hips met the target for anteversion angle, 77% met the target for inclination angle, and 51% met the target for both. There was no correlation between anteversion angle and penetration rate (r = −0.14, p = 0.72) or between inclination angle and penetration rate (r = 0.11, p = 0.35). There was also no difference (p = 0.07) in penetration rate between hips located within the Lewinnek safe zone for both anteversion angle and inclination angle (mean 0.057 mm/year, 95% CI: 0.036 to 0.079 mm/year) and those outside the safe zone (mean 0.062 mm/year, 95% CI: 0.042 to 0.083 mm/year). Acetabular cup position had no effect on the wear rate of highly crosslinked polyethylene at long-term follow-up. Although care should still be taken to correctly position the acetabular cup for stability, highly crosslinked polyethylene is a forgiving bearing material that can withstand a wide range of cup positions without negatively impacting longevity due to wear.
Previous retrieval studies demonstrate increased tibial baseplate roughness leads to higher polyethylene backside wear in total knee arthroplasty (TKA). Micromotion between the polyethylene backside and baseplate is affected by the locking mechanism design and can further increase backside wear. This study's purpose was to examine modern locking mechanisms influence, in the setting of both polished and non-polished tibial baseplates, on backside tibial polyethylene damage and wear. Five TKA models were selected with different tibial baseplate and/or locking mechanism designs. Six retrieval tibial polyethylenes from each TKA model were matched based on time in vivo (TIV), age at TKA revision, BMI, gender, number of times revised, and revision reason. Two observers visually assessed each polyethylene. Primary outcomes were visual damage scores, individual visual damage modes, and linear wear rates determined on micro-computed tomography (micro-CT) scan in mm/year. Demographics were compared by one-way ANOVA. Damage scores, damage modes, and linear wear were analyzed by the Kruskal-Wallis test and Dunn's multiple comparisons test.Purpose
Methods
Patient specific instrumentation (PSI) for total knee replacement (TKR) has demonstrated mixed success in simplifying the operation, reducing its costs, and improving limb alignment. Evaluation of PSI with tools such as radiostereometric analysis (RSA) has been limited, especially for cut-through style guides providing mechanical alignment. The primary goal of the present study was to compare implant migration following TKR using conventional and PSI surgical techniques, with secondary goals to examine whether the use of PSI reduces operative time, instrumentation, and surgical waste. The study was designed as a prospective, randomized controlled trial of 50 patients, with 25 patients each in the PSI and conventional groups, powered for the RSA analysis. Patients in the PSI group received an MRI and standing 3-foot x-rays to construct patient-specific cut-through surgical guides for the femur and tibia with a mechanical alignment. All patients received the same posterior-stabilized implant, with marker beads inserted in the bone around the implants to enable RSA imaging. Intraoperative variables such as time, number of instrumentation trays used, and mass of surgical waste were recorded. Patients underwent supine RSA exams at multiple time points (2&6 weeks, 3&6 months and yearly) with 6 months data currently available. Migration of the tibial and femoral components was calculated using model-based RSA software. WOMAC, SF-12, EQ5D, and UCLA outcome measures were recorded pre-operatively and post-operatively.Background
Methods
The advent of highly cross-linked polyethylene has resulted in improved wear rates and reduced osteolysis with at least intermediate follow-up when compared to conventional polyethylene. However, the role of alternative femoral head bearing materials in decreasing wear is less clear. The purpose of this study was to determine in-vivo polyethylene wear rates across ceramic, Oxinium, and cobalt chrome femoral head articulations. A review of our institutional database was performed to identify patients who underwent a total hip arthroplasty using either ceramic or oxidized zirconium (Oxinium) femoral head components on highly cross-linked polyethylene between 2008 and 2011. These patients were then matched on implant type, age, sex and BMI with patients who had a cobalt chrome bearing implant during the same time period. RSA analysis was performed using the center index method to measure femoral head penetration (polyethylene wear). Secondary quality of life outcomes were collected using WOMAC and HHS Scores. Paired analyses were performed to detect differences in wear rate (mm/year) between the cobalt chrome cohorts and their matched ceramic and Oxinium cohorts. Additional independent group comparisons were performed by analysis of variance with the control groups collapsed to determine wear rate differences between all three cohorts.Background
Methods
Adequate fixation of implant components is an important goal for all arthroplasty procedures. Aseptic loosening is one of the leading causes of revision surgery in total knee arthroplasty. Radiostereometric analysis (RSA) is an imaging technique to measure implant migration, with established migration thresholds for well-fixed, at risk, and unacceptably migrating components. The purpose of the present study was to examine the long-term fixation of a cemented titanium fixed bearing polished tibial baseplate. Patients enrolled in a previous two-year prospective trial were recalled at ten years. All patients received a cemented, posterior-stabilised total knee replacement of the same design implanted by one of three surgeons. Of the original 35 patients, 16 were available for long-term follow-up, with one patient lost to follow-up, nine patients deceased, and a further nine patients unwilling to return to the clinic. Each patient underwent RSA imaging in a supine position using a conventional RSA protocol. Migration of the tibial component in all planes as well as maximum total point motion (MTPM) was compared between all time points (baseline, six weeks, three months, six months, one year, two years) up to the ten year follow-up visits. Outcome scores including the Knee Society Score (KSS), WOMAC, SF-12, and UCLA Activity Score were recorded. At ten years, the mean migrations of the tibial component were less than 0.1 mm and 0.1 degree in all planes relative to the post-operative RSA exam. There was no significant difference in tibial component migration between time points. However, MTPM increased significantly over time (p = 0.002), from 0.23 ± 0.18 mm at six weeks to 0.42 ± 0.20 mm at ten years. At one year, 13 patients had an acceptable MTPM level, three patients had an ‘at risk’ level, and no patient had an ‘unacceptable’ level. No patients were revised at ten years. WOMAC and KSS were significantly improved (p < 0.0001) at the latest follow-up compared to pre-operatively, but there was no difference in SF-12. The median UCLA Activity Score at latest follow-up was six (range, two to eight). The tibial baseplate demonstrated solid fixation at ten years. No patients had an unacceptable MTPM level at one year and no patients were revised at ten years, supporting the use of RSA to predict long-term loosening risk. The low level of tibial baseplate migration found in the present study correlates to the low rate of revision for this implant as reported in individual studies and in joint replacement registries.
Infection following total hip arthroplasty (THA) represents a devastating complication and is one of the main causes for revision surgery. This complication may be treated by irrigation and debridement with head and polyethylene exchange (IDHPE) or a two-stage revision (2SR). Previous studies have reported on the eradication success rates but few have reported patient outcome scores. The purpose of this study was to report patient outcome scores for both IDHPE and 2SR and compare these to a non-infected matched cohort. We hypothesised that both cohorts would have worse outcomes than the control group, and that those who failed an initial IDHPE and required a 2SR would have a worse outcome than those treated initially with a 2SR. A retrospective review identified 137 patients from our institutional arthroplasty database who had an infected primary THA between 1986–2013. We excluded patients with less than one-year follow-up. Mean follow-up was 60 months (12–187 months). A control cohort was identified and matched according to age and Charlton Comorbidity Index (CCI). Harris Hip Scores, Short Form 12 and WOMAC scores were compared between our control group and our infected cohort. Sixty-eight patients were treated with a 2SR and 69 patients were treated with an IDHPE. There was a 59% success rate in eradicating the infection with an IDHPE. All of the 28 patients who failed an IDHPE later went on to a 2SR. Outcome scores for the 2SR cohort were significantly worse than the non-infected controls (p0.05). There was no difference in outcome scores when comparing our 2SR cohort to our failed IDHPE (p>0.05). Previous studies have focused on eradication rates. However, it is important to consider patient outcome scores when deciding the best treatment. Infected patients treated with a successful IDHPE had similar outcomes to non-infected patients. Patients that failed IDHPE and went onto 2SR had similar outcomes to those that had a 2SR alone. IDHPE should still be considered in the treatment algorithm of infected THA.
Previous retrieval studies demonstrate increased tibial baseplate roughness leads to higher polyethylene backside wear in total knee arthroplasty (TKA). Micromotion between the polyethylene backside and tibial baseplate is affected by the locking mechanism design and can further increase backside wear. The purpose of this study was to examine modern locking mechanisms, in the setting of both roughened and polished tibial baseplates, on backside tibial polyethylene wear. Five TKA models were selected, all with different tibial baseplate and/or locking mechanism designs. Six retrieval tibial polyethylenes from each TKA model were matched based on time There were no differences among the groups based on TIV (p=0.962), age (p=0.651), BMI (p=0.951), gender, revision number, or reason for revision. There was a significant difference across groups for mean total damage score (p=0.029). The polished tibial design with a partial peripheral capture locking mechanism and anterior constraint demonstrated a significantly lower score compared to one of the roughened tibial designs with a complete peripheral-rim locking mechanism (13.0 vs. 22.1, p=0.018). Otherwise, mean total damage scores were not significant between groups. As far as modes of wear, there were identifiable differences among the groups based on abrasions (p=0.005). The polished design with a tongue-in-groove locking mechanism demonstrated a significantly higher score compared to both groups with roughened tibial baseplates (5.83 vs. 0.83, p=0.024 and 5.83 vs. 0.92, p=0.033). Only the two designs with roughened tibial baseplates demonstrated dimpling (5.67 and 8.67) which was significant when compared against all other groups (p0.99). No other significant differences were identified when examining burnishing, cold flow, scratching, or pitting. No polyethylene components exhibited embedded debris or delamination. Total damage scores were similar between all groups except when comparing one of the polished TKA design to one of the roughened designs. The other TKA model with a roughened tibial baseplate had similar damage scores to the polished designs, likely due to its updated locking mechanism. Dimpling wear patterns were specific for roughened tibial baseplates while abrasive wear patterns were identified in the design with a tongue-in-groove locking mechanism. Our study showed even in the setting of a roughened tibial baseplate, modern locking mechanisms decrease backside wear similar to that of other current generation TKA designs.
Studies that have previously examined the relationship between inclination angle and polyethylene wear have shown increased wear of conventional polyethylene with high inclination angles. To date, there have been no long term An institutional arthroplasty database was used to identify patients who had metal-on-highly crosslinked polyethylene primary total hip arthroplasty (THA) using the same component design with a minimum follow up of 10 years ago. A modified RSA examination setup was utilised, recreating standard anteroposterior (AP) and cross-table lateral exams in a single biplane RSA acquisition. Three dimensional head penetration was measured using the centre index method. The same radiographs were used to measure inclination angle and anteversion. Spearman correlation was used to show an association between the parameters of acetabular position and wear rate. A total of 43 hips were included for analysis in this study. Average follow-up was 12.3 ± 1.2 years. The average linear wear rate was calculated to be 0.066 ± 0.066 mm/year. Inclination angle was not correlated with polyethylene wear rate (p=0.82). Anteversion was also not correlated with polyethylene wear rate (p=0.11). There was no statistical difference between wear rates of hips within Lewinnek's “safe zone” and those outside this “safe zone” (p=0.11). Males had a higher wear rate of 0.094 ± 0.089 mm/year compared to females with a wear rate of 0.046 ± 0.032 mm/year (p=0.045). At long term follow up of greater than 10 years, highly cross linked polyethylene has very low wear rates. This excellent tribology is independent of acetabular position, but gender did impact wear rates. Due to the low wear rates, follow-up of even longer term is suggested to examine variables affecting wear.
Complications involving the patellofemoral joint are a source of anterior knee pain, instability, and dysfunction following total knee arthroplasty. “Overstuffing” the patello-femoral joint refers to an increase in the thickness of the patellofemoral joint after a total knee replacement compared to the preoperative thickness. While biomechanical studies have indicated that overstuffing the patellofemoral joint may lead to adverse clinical outcomes, limited clinical evidence exists to support this notion. The purpose of this study is to evaluate the effect of changing the thickness of the patellafemoral joint on functional outcomes following total knee arthroplasty. Our institutional arthroplasty database was used to identify 1347 patients who underwent a primary total knee arthroplasty between 2006 and 2012 with the same component design. Standard preoperative and postoperative anteroposterior, lateral, and skyline radiographs were collected and measured for patello-femoral overstuffing. These measurements included anterior patellar displacement, anterior femoral offset, and anteroposterior femoral size. These measurements were correlated with patient outcome data using WOMAC, KSS scores, and postoperative range of motion. Multiple linear regression analysis was used to assess the association between stuffing and functional outcomes. A total of 1031 patients who underwent total knee arthroplasty were included. Increased anterior patellar displacement, a measure of patellofemoral joint thickness, was associated with decreased WOMAC scores (p=0.02). Anterior femoral offset (p=0.210) and anteroposterior femoral size (p=0.091) were not significantly associated with patient functional outcomes. Postoperative range of motion (ROM) was not associated with patellofemoral stuffing (p=0.190). The current study demonstrated that functional outcomes are adversely affected by patellofemoral overstuffing. Based on these results, caution is encouraged against increasing the thickness of the patellofemoral joint, particularly on the patellar side of the joint.
The philosophy of cemented total hip arthroplasty (THA) femoral components has become polarised. At one extreme are polished, collarless, tapered devices that are expected to subside; at the other extreme are roughened, non-tapered implants with a collar designed not to subside. Radiostereometric analysis (RSA) allows the accurate measurement of implant movement and has been extensively used for measurement of the Data from two previous prospective RSA trials with two-year follow-up were pooled. The first group included 36 patients who received a Spectron (Smith & Nephew, Memphis, USA) cemented stem. The second group included 13 patients who received an Exeter (Stryker, Mahwah, USA) cemented stem, and 15 patients who received a CPCS (Smith & Nephew, Memphis, USA) cemented stem. All patients underwent RSA examinations shortly post-operation, at 6 weeks, 3 months, 6 months, 1 years, and 2 years. Migration and rotation of the femoral stems was measured at each time point relative to the post-operative exam, and compared between the two groups. There was no difference in age at surgery (Spectron 78 ± 6 years, Exeter/CPCS 77 ± 5 years, p = 0.43), BMI (Spectron and Exeter/CPCS 28 ± 5 kg/m2, p = 0.92), or percentage of male patients (Spectron 23% male, Exeter/CPCS 21% male) between the implant groups. Subsidence was significantly greater (p < 0.0001) at all time points from three months to two years for the Exeter and CPCS stems (0.94 ± 0.39 mm at two years) compared to the Spectron stem (0.05 ± 0.16 mm at two years). There was no significant difference between the stem types for medial-lateral translation (p = 0.07) or anterior-posterior translation (p = 0.49), or for anterior-posterior tilt (p = 0.15), internal-external rotation (p = 0.89), or varus-valgus rotation (p = 0.05). Implant material, design, and surface finish are all factors in the long-term performance of cemented femoral hip implants. In this study, both femoral stem designs had a magnitude of sub-sidence that was within the limits of what is considered to be safe with respect to long-term performance. The continuous subsidence of the Exeter and CPCS stems is consistent with previous reports in the literature.
Trunnionosis in modular hip arthroplasty has recently been recognised to be clinically important. Gaining an understanding of how the material interface at the head-trunnion affects the tribology at the modular junctions has current clinical implications as well as an implication on future implant selection and material choice. This matched-cohort study aims to compare tribocorrosion between ceramic and cobalt-chromium trunnions and to investigate other factors that contribute to the difference in tribocorrosion if present. All hip prostheses retrieved between 1999 and 2015 at one centre were reviewed. Fifty two ceramic heads were retrieved, and these were matched to a cobalt-chromium cohort according to taper design, head size, neck length and implantation time in that order. The two cohorts were similar in male:female ratio (p=0.32) and body mass index (p=0.15) though the ceramic group was younger than the cobalt-chromium group (56.6 (+/−)13.5 years for ceramic group vs 66.3 (+/−14.4) years for cobalt-chromium group; p=0.001). There was no significant difference in the reasons for revision between the two groups (p=0.42). The femoral head trunnions were examined by two independent observers using a previously published 4-point scoring technique. The trunnions were divided into three zones: apex, middle and base. The observers were blinded to clinical and manufacturing data where possible. Ceramic head trunnions demonstrated a lower median fretting and corrosion score at the base zone (p<0.001), middle zone (p<0.001) and in the combined score (p<0.001). In a subgroup analysis by head size, ceramic heads had a lower fretting and corrosion score at 28mm head diameter (p<0.001). Within the ceramic group, taper design had a significant effect on fretting and corrosion in the apex zone (p=0.04). Taper design also had a similar effect in the cobalt-chromium group in the apex zone (p=0.03). For the ceramic trunnions, the largest effect was contributed by the difference between the 11/13 taper and the 12/14 taper. For the cobalt-chromium trunnions, the largest effect was contributed by the difference between the 5 degree 38′ 37″ taper and type 1 taper. Ceramic head trunnions showed a significantly lower fretting and corrosion score as compared to cobalt-chromium trunnions. Ceramic heads had a lower score than cobalt-chromium heads at 28mm head diameter. Taper design had an effect on fretting and corrosion within each cohort.
The advent of highly cross-linked polyethylene has resulted in improved wear rates and reduced osteolysis with at least intermediate follow-up when compared to conventional polyethylene. However, the role of alternative femoral head bearing materials in decreasing wear is less clear. The purpose of this study was to determine in-vivo polyethylene wear rates across ceramic, Oxinium, and cobalt chrome femoral head articulations. A review of our institutional database was performed to identify patients who underwent a total hip arthroplasty using either ceramic or oxidised zirconium (Oxinium) femoral head components on highly cross-linked polyethylene between 2008 and 2011. These patients were then matched on implant type, age, sex and BMI with patients who had a cobalt chrome bearing implant during the same time period. RSA analysis was performed using the centre index method to measure femoral head penetration (polyethylene wear). Secondary quality of life outcomes were collected using WOMAC and HHS Scores. Paired analyses were performed to detect differences in wear rate (mm/year) between the cobalt chrome cohorts and their matched ceramic and Oxinium cohorts. Additional independent group comparisons were performed by analysis of variance with the control groups collapsed to determine wear rate differences between all three cohorts. A total of 68 patients underwent RSA analysis. Fifteen patients with a ceramic femoral head component and 14 patients with an Oxinium femoral head component along with the same number of matched patients with cobalt chrome femoral head component were included in the analysis. The time This study presents evidence of a greater wear rate (mm/year) of the Oxinium femoral head component compared to a cobalt chrome femoral head component. This difference was not demonstrated in the ceramic femoral head component. Despite this difference, there were no clinical differences as measured by the HHS and WOMAC. Future research should focus on factors that may contribute to the higher wear rate seen in the Oxinium cohort.
Total joint arthroplasty is commonly associated with post-operative anemia. Blood conservation programs have been developed to optimise patients prior to surgery. Epoetin Alfa (Eprex) or intravenous (IV) iron transfusions are two modalities that can be used pre-operatively to optimise hemoglobin and ferritin levels. There are, however, potential complications and increased costs associated with their use. Oral iron is a less costly option for those undergoing surgery but requires more time to take effect. There are no studies to date that examine the effects of an early screening program utilising oral iron supplementation prior to total joint arthroplasty. The purpose of this study is to evaluate the effect of implementing early pre-operative oral iron supplementation on patients prior total joint arthroplasty. A retrospective review of patients undergoing total joint arthroplasty was performed using our institution clinical informatics database. We identified all patients seen in pre-admission clinic (PAC) between Jan 1, 2009 and March 31, 2010 representing our control group. We then identified all patients seen in PAC between October 1, 2012 and December 31, 2013. Patients in this cohort received screening blood work when booked for surgery, and oral iron supplementation was given to patients with hemoglobin of less than 135g/L or ferritin less than 100ug/L, thus representing our treatment group. Patients undergoing revision, uni-compartment knee arthroplasty and bilateral arthroplasties were excluded from the study. Pearson Chi-Square tests were used to calculate significance between groups with main outcomes including pre-admission hemoglobin, and pre-operative requirements for Eprex or IV iron. In our control group, we identified 354 patients (25.6%) with hemoglobin less than 130 g/L at time of pre-admission clinic. In our treatment group, this number dropped significantly to only 16.4% of patients (p<0.005). Implementation of an early screening program using oral iron supplementation resulted in a decrease in the number of patients with hemoglobin lower than 130 g/L at the time of pre-admission clinic. There was also a significant decrease in the use of Eprex and IV iron pre-operatively in the patients in the early screening program. These results encourage the use of early oral iron supplementation for patients with hemoglobin less than 135 g/L or ferritin less than 100ug/L in order to optimise patients prior to total joint arthroplasty.
Unicompartmental versus total knee arthroplasty has been a debated topic for decades. The purpose of this study was to compare the survivorship and clinical outcomes of a large primary total knee arthroplasty versus unicompartmental knee arthroplasty cohort. A consecutive series of 6352 TKAs and 296 UKAs with a minimum of one year follow-up were evaluated. Pre-operative scores, latest scores, and change in clinical outcome scores (KSCRS, SF12, WOMAC) were compared and tested for significance using the students t-test.Purpose
Method
The pros and cons of general anesthesia versus spinal anesthesia in total hip arthroplasty has been a long debated topic. The purpose of this study was to compare the surgical times, blood loss and transfusion requirements between anesthetic types in patients undergoing primary total hip arthroplasty. A consecutive series of 1600 THA procedures with complete preoperative and postoperative data were evaluated. Twenty eight percent of procedures were performed with a general anesthetic (GA), 67% with a spinal anesthetic (SP) and 5% with a combination of the two. Outcomes were compared and tested for significance using the Independent Samples Kruskal Wallis or Pearson Chi-Square analysis.Purpose
Method
The purpose of this study was to compare the outcomes and complications of normal weight, class one obese (BMI=30-34.9 kg/m2) and superobese (BMI≥50 kg/m2) primary total knee replacement (TKR) patients. Between January 1995 and December 2005, 4104 primary TKR were performed in our centre. Patients were stratified for their obesity level according the World Health Organisation (WHO) and current surgical literature classification. Sixty-seven superobese patients (group one) were identified. They were matched with normal weight (group two) and class one obese (group three) primary TKR patients for sex, age, side, preoperative diagnosis, implants used, time since surgery and preoperative SF-12 mental component summary score (MCS). Patient clinical outcomes (WOMAC, SF-12 and Knee Society scores), radiographs, complications, readmissions, and revisions rates were compared for normal BMI, class one obese and superobese patients.Purpose
Method
The patella provides a mechanical advantage to the knee extensor mechanism. Patellectomy, performed for trauma or patellofemoral arthrosis, does not preclude the development of tibiofemoral arthrosis. Total knee arthroplasty is the mainstay of treatment for tibiofemoral arthrosis. The purpose of this study was to evaluate the outcomes of total knee arthoplasty in patients who previously underwent patellectomy. A retrospective analysis was completed on a prospectively collected database to identify all patients who underwent total knee arthroplasty following a previous patellectomy. Sixty-one total knee arthroplasties in 57 patients were identified. Patient demographics as well as functional outcome scores, including WOMAC and Knee Society Scores, were evaluated.Purpose
Method
Sixty four patients undergoing total hip replacement (THR) were randomized to receive a peri-articular intra-operative multi modal drug injection or to receive no injection. All patients received patient controlled analgesia (PCA) for 24 hours after surgery. Patients receiving the peri-articular injection showed significantly less PCA consumption 6 hours postoperatively (P<
0.002). The 24 hour PCA requirement post surgery was also less (P<
0.009). The VAS score for pain on activity in the post anaesthetic care unit (PACU) was significantly less for injected patients (P<
0.04). The VAS satisfaction score for injected patients in the PACU and 4 hours post-operatively showed no statistical difference. Peri-articular intra-operative injection with multimodal drugs can significantly reduce post-operative patient controlled analgesia requirements and pain on activity in patients undergoing total hip replacement with no apparent increase in risk.
The clinical results were evaluated with SF12, WOMAC, and KSCRS performed preoperatively and postoperatively at 5 and 10 years. A radiographic analysis was performed using x-rays of the last available follow-up.
There is an increasing trend towards performing a high tibial osteotomy (HTO) with a medial opening wedge technique. Amongst the potential advantages is easier conversion to a total knee replacement (TKR), although literature regarding this is scarce. We report our early clinical and radiological results, along with the technical issues encountered. From our database, we identified thirty-one patients who had undergone thirty-two TKRs after medial opening wedge HTOs. Clinic and operative records were reviewed, and our database used for knee society scores. Those patients not seen in the last twelve months were reviewed in clinic. All pre- and postoperative radiographs were reviewed. The average age of the patients was fifty-seven years, and the average time from HTO to TKR was 4.5 years. Difficulties with patella eversion were seen in 12.5%, and the knee balanced easily in 85% of cases. The tibia had minimal deformity in most cases, and all osteotomies were healed at the time of conversion. A stem was used in ten cases, and only if metalwork was removed at the time of conversion (which was done in twenty-three of the thirty-two). Minimum one year follow-up was available for twenty-six patients, with a mean follow-up time of twenty-eight months (range twelve to ninety-three months). The average Knee Society knee score was eighty-eight, function score seventy-five, and total score one hundred and sixty-two. Compared to non-matched group of 1149 primary TKRs (of older average age), the knee score was significantly lower, and there was a higher percentage of patients in the poor category. Poor results correlated strongly to the presence of chronic pain or workers compensation issues, and also to whether the knee had undergone revision HTO prior to TKR. We conclude that the conversion of a medial opening wedge HTO to a TKR is relatively straightforward technically, and some aspects are easier than performing a TKR after a lateral closing wedge osteotomy (using historical controls). The clinical results appear inferior to that of a TKR performed without a prior osteotomy, although the results in our osteotomy group were skewed by a small group of chronic pain and workers compensation cases.
This study reports on the clinical and wear performance of a prospective randomised controlled trial comparing highly cross-linked (XLPE) to conventional polyethylene (PE) in total hip arthroplasty at five years minimum follow-up. One hundred patients enrolled in a prospective randomised controlled trial received identical hybrid total hip arthroplasties with the exception of the polyethylene insert. Fifty patients received a PE liner (2.5 MRads; gamma-in-nitrogen sterilization) and fifty patients received a XLPE liner (10Mrads; gas-plasma sterilization). Clinical outcomes were determined using Harris Hip, WOMAC and SF-12 scores by an independent study nurse. Femoral head penetration rates were determined using a validated radiographic technique (Hip Analysis Suite 8.0.1.1) based on radiographs at six weeks, one year and yearly post-operatively. Linear regression analysis was performed for both the entire polyethylene groups and on each patient, where the slope represents the steady state head penetration rate (after bedding in) from one to five years follow-up. None of the patients were lost to follow-up, however, nine patients were deceased before their five year follow-up. Two patients have been revised for loose stems. At average follow-up of 6.0 years (range 5.1–6.8 years), there were no differences in Harris Hip, WOMAC or SF-12 scores. XLPE had a significantly lower (p= 0.03) steady-state head penetration rate of 0.018 mm/year compared to 0.050 mm/year for XLPE (approximately 64% reduction). Analysis of individual patient’s head penetration rates demonstrated a similar significantly lower rate with XLPE (0.004 ± 0.067 mm/year) compared to PE (0.045 ± 0.083 mm/year). Interestingly, when examined by gender, the male PE group had a significantly higher head penetration rate (0.081 ± 0.084 mm/year) than both the male and female XLPE (−0.013 ± 0.104, 0.011 ± 0.074 mm/year, respectively). At minimum five years follow-up, there were no clinical differences between groups. After bedding-in, there was a significant lower head penetration rate with XLPE compared to PE. Thus, mid-term follow-up appears to demonstrate a significant wear reduction (based on head penetration rates) afforded by first generation XLPE. Long-term follow-up is required to demonstrate the clinical benefit of this new material.
The pathogenesis of osteolysis in failed total hip arthroplasty is not fully understood. The purpose of this study is to identify CD4+CD25+ Regulatory T cells in periprosthetic tissues in failed total hip replacements secondary to osteolysis. Intra-operative tissue samples and peripheral blood were collected from patients undergoing revision total hip arthroplasty surgery. Regulatory T cells were present in the tissues, and significantly increased in the peripheral blood in patients with failed total hips compared to normal controls. Further characterization of these regulatory T cells are warranted as they may play a role in osteolysis in loose total hip replacements. Osteolysis remains the most common complication following total joint arthroplasty. To date, no authors have investigated the role of CD4+CD25+ regulatory T cells (TREG) participating in the osteolytic pathogenesis. The purpose of this study is to quantitate the presence of TREG cells in periprosthetic tissues in failed total hip replacements secondary to osteolysis. Fifteen consecutive patients booked for revision total hip arthroplasty secondary to osteolysis were included. Tissue samples were collected: peripheral blood (PB), synovial fluid (SF), synovial tissue (ST), and interface tissue (IT) between the failed component and the bone defect. Total lymphocytes were isolated and analyzed using fluorescent-tagged antibody cell sorting (FACS) for the presence of TREG cells. Frozen sections of ST and IT were analyzed with immunohistochemistry for TREG cells. TREG cells were significantly upregulated (p<
0.01) in the PB (68%) of revision hip patients compared to normal controls PB (44%). In the synovial tissue (ST) and interface tissue (IT), 57% of the lymphocytes isolated were TREG cells. The presence of TREG cells in the ST and IT were confirmed with immunohistochemistry. TREG cells are upregulated in the peripheral blood of patients with failed total hips secondary to osteolysis. The TREG cells are also present in the synovial tissue and interface tissue. Evidence for involvement of regulatory T cells contribute to our understanding of this complex biologic response to artificial wear particles. Functional studies of these TREG cells are warranted as they are upregulated in patients with loose total hip replacements.
Fixed bearing and mobile bearing knee designs are both currently used in clinical practice with little evidence- based research available to determine superiority of one system. We performed a prospective, randomized, blinded clinical trial to compare a mobile bearing to two standard fixed bearing implants. A single observer was used to measure all range of motion scores. We evaluated the short and long- term outcomes of the SAL® (mobile bearing) versus the AMK® and Genesis II® (fixed bearings) total knee joint replacements. Minimum two- year follow-up revealed no differences in the outcome measures (WOMAC, SF-12, Knee Society Clinical Rating System). The purpose of this study was to compare the results between a cruciate retaining mobile bearing total knee (SAL®, Sulzer) and two cruciate retaining fixed bearing total knee prostheses (AMK®, Depuy and Genesis II®, Smith and Nephew). Ninety patients were randomized to receive a SAL, AMK, or GenesisII prostheses. Patients were evaluated pre-operatively, at three, twelve months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated. No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two year follow up, and one patient was revised for infection at 6 months leaving eighty-seven patients at an average follow-up of 3.37 years (range 2.91 – 4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL - 167, AMK – 158, GenesisII – 166). There were no differences in knee flexion at two years (SAL – 117°, AMK – 115°, GenesisII – 118°). No differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses. In this prospective randomized clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.
Fixed bearing and mobile bearing knee designs are both currently used in clinical practice with little evidence- based research available to determine superiority of one system. We performed a prospective, randomized, blinded clinical trial to compare a mobile bearing to two standard fixed bearing implants. A single observer was used to measure all range of motion scores. We evaluated the short and long- term outcomes of the SAL® (mobile bearing) versus the AMK® and Genesis II® (fixed bearings) total knee joint replacements. Minimum two- year follow-up revealed no differences in the outcome measures (WOMAC, SF-12, Knee Society Clinical Rating System). The purpose of this study was to compare the results between a cruciate retaining mobile bearing total knee (SAL®, Sulzer) and two cruciate retaining fixed bearing total knee prostheses (AMK®, Depuy and Genesis II®, Smith and Nephew). Ninety patients were randomized to receive a SAL, AMK, or GenesisII prostheses. Patients were evaluated pre-operatively, at three, twelve months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated. No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two year follow up, and one patient was revised for infection at 6 months leaving eighty-seven patients at an average follow-up of 3.37 years (range 2.91 – 4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL - 167, AMK – 158, GenesisII – 166). There were no differences in knee flexion at two years (SAL – 117°, AMK – 115°, GenesisII – 118°). No differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses. In this prospective randomized clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.
The Genesis II total knee prosthesis was a successor to the Genesis I TKR in which three degrees of external rotation was built into the femoral component to improve patellofemoral tracking and eliminate rotational incongruity. The midterm (minimum five year) results of three hundred and forty-three Genesis II cemented components were reviewed in three hundred and twenty-four patients. Kaplan-Meier survivorship was 98% at a mean 7.6 years. The focus of this study was to analyze the minimum five- year results of patients receiving either a cruciate-retaining, posterior stabilizing, or mobile bearing Genesis II TKR. Further analysis was performed to delineate differences between subsets of this population. Data from a consecutive series of three hundred and twenty-four patients receiving three hundred and sixty-seven Genesis II TKR’s between February 1996 and July 1999 was collected. Patients were evaluated pre-operatively, at six weeks, three months, six months and annually thereafter, using the Knee Society Clinical Rating System and the Western Ontario MacMaster Osteoarthritis Index. A Kaplan-Meier Survivorship was performed on the consecutive series. Statistical analyses were used to delineate significant differences between subsets of patients. There were three hundred and sixty-seven procedures (one hundred and sixty-nine cruciate-retaining, one hundred and sixty-six posterior stabilized and six mobile bearing designs) performed on three hundred and twenty-four patients. At the time of evaluation, forty-five (13%) patients were deceased, twenty-four (7%) patients were unavailable for evaluation and nine (2%) knees had been revised. A 98% implant survivor-ship was calculated at a mean time of 7.6 years. These are the first mid-term (minimum five year) clinical results of the Genesis II TKR, which continues to function well. Kaplan-Meier survivorship was 98% at a mean 7.6 years.
Isolated liner exchange in revision total hip arthroplasty for the treatment of polyethylene wear is an increasingly common surgical procedure. Twenty-four hips underwent this procedure via the direct lateral approach and were prospectively followed clinically and radiographically. Accessible osteolytic lesions were curetted and bone grafted. At a mean follow-up of forty months, a significant clinical improvement was observed. One cup collapsed into an osteolytic lesion postoperatively; all other lesions regressed. No dislocations have occurred. Isolated liner exchange via the direct lateral approach may reduce dislocation rates while avoiding the morbidity associated with the removal of well-fixed components. The purpose of this study was to evaluate the clinical and radiographic results of isolated liner exchange in revision total hip arthroplasty (THA) for osteolysis and polyethylene wear via the direct lateral surgical approach. Retention of well-fixed implants avoids unnecessary bone loss at revision surgery. Previous studies report a significant dislocation rate with isolated liner exchange. Revision via the direct lateral surgical approach may reduce the dislocation rate in surgery for acetabular osteolysis. Twenty-four hips that underwent an isolated liner exchange revision procedure via the direct lateral approach were prospectively followed. Accessible osteolytic lesions were curetted and bone grafted. Harris Hip Score, WOMAC Index, and radiographic analysis were recorded. The area of osteolytic lesions was calculated using a computer imaging technique. At mean follow-up of forty months, all except one of the osteolytic lesions had regressed in size. Mean Harris Hip scores improved from sixty-nine to eighty-three and WOMAC indices improved from thirty-seven to twenty-four. No dislocations have occurred. One cup collapsed into an osteolytic lesion postoperatively, requiring an acetabular revision procedure. Isolated liner exchange is a promising technique that avoids the removal of well-fixed acetabular implants. The increased dislocation rate associated with revision THA may be reduced and osteolytic lesions may be debrided and bone grafted through the direct lateral approach. Isolated liner exchange via the direct lateral approach reduces the dislocation rate in THA. Retention of wellfixed implants and bone grafting is a procedure that preserves bone stock and addresses osteolytic lesions at revision surgery.
The purpose of this study was to determine contact patterns in cementless acetabular cups using a novel computed tomography (CT) scan analysis technique. Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive one of three cup designs. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone pros-thesis contact. The purpose of this study was to determine contact patterns in cementless acetabular cups using computed tomography (CT) scan analysis. Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive a hemispherical cup, a dual geometry cup, or a spiked cup. After radiographic templating, an experienced orthopaedic team prepared the specimens and implanted the acetabular cups. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. Contact was defined as a bone-prosthesis distance of 0.5 mm or less. The mean amount of cup contact was 40.4% (SD=8.2%) in the hemisphere group, 24.7% (SD=2.3%) in the dual geometry group, and 29.7% (SD=9.5%) in the spiked group. Colour mapping of the bone-prosthesis gap was used to identify contact/non-contact regions along the acetabular contour for all cup designs. Preliminary work with this CT analysis technique demonstrates differences in the amount and distribution of contact in the acetabular cup designs. Future work will involve development of an imaging phantom to clarify error, use of the technique with different cup designs and reaming techniques, and comparison of this technique with conventional CT scan techniques. This study outlines a novel CT analysis technique for quantitatively determining bone-prosthesis contact for cementless acetabular cups. The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone prosthesis contact.
One hundred and thirty-one cemented femoral stems inserted during revision total hip arthroplasty were reviewed to determine component survival. Harris Hip scores and complete radiographs were analysed. Survival at 10.5 years was 86.9%. Radiographically, 76.9% of the remaining components were classified as stable or possibly loose. Chi-square analysis of demographic and surgical factors determined age <
60 years, male gender and stems >
200 mm in length contributed significantly to failure (p <
0.05). Contrary to published results, we found that longer stems were more susceptible to failure. Revision femoral THA to a cemented component is an effective procedure that exhibits good long-term survival. The purpose of this study was to determine the long-term survival of cemented femoral components in revision total hip arthroplasty (THA) and to identify factors significant to implant failure. Cemented femoral components demonstrate good long-term survival and remain a suitable option for revision THA for hips with an intact cortical tube. We report high long-term survival for this increasingly popular procedure, and contradict published results regarding the relationship between stem length and failure. A consecutive series of one hundred and thirty-one THA revisions using a cemented femoral component were reviewed. Ninety-four hips in eighty-five patients alive >
six years post-operatively were studied with a mean follow-up of 10.5 years. Hips excluded from analysis were thirty deceased and seven lost to follow-up before six years post-operatively. Implant success was graded radiographically and by comparing pre-operative to recent Harris Hip scores. Of the ninety-four hips, fifteen (16%) femoral components were subsequently revised; nine (9.6%) for aseptic loosening, three (3.2%) for periprosthetic fracture, and one (1.1%) for each of stem fracture, instability, and sepsis. Survival at 10.5 years was 86.9% for all reasons and 91.0% for aseptic loosening as an endpoint. 76.9% of the retained components were radiologically classified as stable or possibly loose at follow-up. Factors significant for failure included age at revision <
sixty years (p = 0.003), male patients (p = 0.036) and stems >
200 mm in length (p = 0.024).
Constrained acetabular components are a useful adjunct for the potentially unstable hip arthroplasty. There have been concerns over implant failure and early acetabular component loosening secondary to the increased implant constraint. We report the results of a constrained ace-tabular component used as treatment for dislocating hips and as prophylaxis against dislocation in high risk primary and revision hip arthroplasty. At average 3.1 years follow-up only one insert of eighty-nine inserted had failed. No cups have demonstrated radiographic or clinical evidence of loosening. We conclude this implant is safe and effective for both the prevention and treatment of hip instability. To review the effectiveness and durability of a constrained acetabular component used to treat and prevent recurrent dislocation after total hip arthroplasty Constrained acetabular components of this type provide both an excellent treatment and preventative option in total hip arthroplasty. There is no evidence of accelerated cup loosening and the implant failure rate remains acceptable despite the increased constraint. Constrained acetabular components have been mainly used as a salvage option for dislocating hip arthroplasty. There have been concerns over implant failure and early acetabular component loosening secondary to the increased implant constraint. Use of this implant can prevent dislocation in high risk patient groups (eg: revision surgery) without compromising implant longevity. This significantly reduces the potential morbidity associated with hip instability. Eighty-nine patients received the tripolar constrained acetabular component. Fifteen were inserted for recurrent dislocation whilst seventy-two were inserted in patients felt to be at high risk of dislocation (forty-nine for intra-operative instability at revision surgery, twenty-five for primary THA in patients with poor compliance, neurological conditions or deficient abductor mechanism). One implant failed by component dissociation at eighteen months. All other recurrent dislocators remained stable. There was no evidence of accelerated component loosening at medium term review (range twelve – eighty three months, average thirty-seven months) Radiographic and clinical data was prospectively collected on eighty-nine patients who had the constrained acetabular component inserted.
Controversy continues to exist regarding the choice of a cementless femoral component in a primary total hip arthroplasty. Both proximally coated tapered stems and fully coated cylindrical stems have excellent clinical results. The incidence of both thigh pain and proximal femoral stress shielding and multiple validated outcome measures were evaluated in a prospective randomized clinical trial with a minimum of two year follow-up comparing a proximally coated tapered femoral stem to a fully coated cylindrical femoral stem. A prospective randomized clinical trial (RCT) was performed comparing a cylindrical cobalt chrome fully coated femoral stem (Prodigy, Depuy, Warsaw, IN) to a tapered, titanium, proximally porous coated stem (Synergy, Smith &
Nephew, Memphis, TN) with respect to thigh pain, femoral stress shielding and multiple outcome measures. One hundred and ninety-four patients were enrolled and evaluations were performed pre-operatively, three months, six months and annually. Multiple outcome measures (Harris Hip Score, SF12, WOMAC, Patient Satisfaction Questionnaire, Thigh Pain Questionnaire) were obtained. Sixty-one of these patients were randomized to receive a bone density scan pre-operatively, two weeks post-operatively, six months and annually. Twelve patients were unavailable for two-year follow-up, leaving one hundred and eighty-two patients evaluated. No significant differences were demonstrated in thigh pain incidence or the multiple outcome measures. Bone density scans demonstrated significantly greater bone density (p<
0.005) in the tapered stem versus the cylindrical stem patients at two-week evaluations from distal femoral reaming. Both stem designs demonstrated statistically significant bone loss in Gruen zones one, six, seven between the two-week and one and two-year evaluations. There were no differences between stem designs although the Prodigy stem demonstrated trends towards greater bone loss in Gruen zones six and seven. This prospective RCT demonstrated no difference in thigh pain incidence and multiple outcome measures between patients receiving a proximally coated tapered versus a fully coated cylindrical femoral component. Both stem designs demonstrated statistically significant proximal femoral bone loss between the post-operative and two-year evaluations; however, there were no differences between stem designs.
This Blinded Randomized Clinical Trial outlines: how peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. Patients who received the injection demonstrated greater satisfaction and pain relief. Finally, patients in the injected group did not show any signs of cardio and central nervous system toxicity. Post-operative analgesia can be associated with troublesome side effects. Good peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. The purpose of this study was to assess a novel cocktail for peri-articular analgesia after total knee replacement. Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for twenty-four hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at six week follow up. PCA consumption and overall analgesic requirement were measured. PCA use at six, twelve and over twenty-four hours post surgery was significantly less in patients receiving the injection (p<
0.01, p=0.016, p<
0.01). Patient satisfaction in PACU and four hours post operation was greater (p=0.016, p=0.013). VAS for pain during activity in PACU and at four hours were significantly less (p=0.04, p=0.007) in the injected group. The average ROM at six weeks was no different. Overall hospital stay and the incidence of wound complications were not different between the two groups. Peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Patient satisfaction and pain relief is greater in the injection group. No cardio and central nervous system toxicity was observed. Our novel cocktail of ketorolac, epimorphine, epinephrine and ropivacaine provides superior pain relief with no adverse side effects.
Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. This study reviews AP and lateral radiographs for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months). Reduced implant survivorship due to aseptic loosening has prompted research into alternative bearing materials. Simulator testing is useful but clinical studies are the gold standard to evaluate the wear characteristics of new bearing materials. On hundred and twelve patients matched for sex, age, body mass index, primary pathology, Charnley grade, and follow up underwent uncemented total hip replacement using an identical implant. Group One (sixty-four patients) had a RAM extruded liner (GUR 4150 HP) and Group Two (forty-eight patients) had a compression molded liner (Montell H 1900). HMWPE sterilisation regimes were identical. AP and lateral radiographs were analysed for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months). Preliminary data show a linear and volumetric wear rate in Group One of 0.067 mm/yr and 26 mm3/year respectively between two years to maximum follow up. Similarly, the wear rates for Group Two were 0.132 mm/yr and 45 mm3/year respectively. There was no statistical difference in acetabular osteolysis between Group One (16.3%) and Group Two (15%) patients at maximum follow up. Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. Quality of the wear debris is more likely to be important in producing aseptic loosening than actual wear rate.
Fifty-one prospectively followed Contour_ acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). To date, four reoperations were required (two each for sepsis and instability) with no failures due to aseptic loosening. The Kaplan-Meier Survival Rate for any reoperation was 87% at 6.4 years. Short to mid-term follow-up of a single type of acetabular reconstruction cage, inserted through the lateral approach, demonstrated this to be a successful reconstruction option in the management of large acetabular bone defects. This study reports the mid-term results of a single design of acetabular reconstruction cage inserted through the direct lateral approach. At minimum three years follow-up (range 3 to 6.4 yrs.), there were no failures due to aseptic loosening with only four of fifty-one cases requiring reoperation (two sepsis, two instability). This review supports the use of the reconstruction cage, inserted through the lateral approach, for large defects that cannot be managed with a hemispherical porous implant. The use of the reconstruction cage in our center is reserved for large defects that cannot be managed with a hemispherical porous implant because of insufficient bone stock for initial implant stability and/or host bone contact for in-growth. Fifty-one consecutive prospectively followed Contour_ (Smith and Nephew) acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). The majority of cases were AAOS Type Three and Four defects in which morsellized allograft was used in forty-nine cases and structural graft in three cases. Harris hip scores improved from 32.1±17.8 pre-op to 65.3±24.1 at most recent follow-up. Defining any acetabular reoperation as a failure, four of the fifty-one cages were considered to have failed giving a Kaplan-Meier Cumulative Survival Rate of 87% at 6.41 years. Two reoperations were for recurrent dislocation and the other two for sepsis. None of the fifty-one cages have been revised for aseptic loosening to date.
The timing of liner exchange for retroacetabular oste-olysis in THA remains uncertain. Liner exchange should be done before the shell becomes loose. The purpose of this study was to determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Osteolytic lesions were quantified radiographically using three different measures. Implant stability was confirmed intraoperatively. Percent of shell circumference with surrounding osteolysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary. The timing of liner exchange for retroacetabular osteolysis in cementless THA remains uncertain. Liner exchange should be done before the shell becomes loose. To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Osteolytic areas differ between loose and stable shells. Between 1992 to 2002, seventy-one cementless shells of the same design were revised at our institution; forty-six were for aseptic retroacetabular osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolytic areas and percent of shell circumference associated with lesions. Implant stability was confirmed intraoperatively. Of twenty-six stable and twenty loose shells, the average area of osteolysis on AP radiographs showed no significant difference (Stable 591mm2, Loose 630 mm2, p greater than 0.05); whereas, lateral radiographs demonstrated a significant difference (Stable 546 mm2, Loose 837 mm2, p 0.05). The percentage of shell circumference with associated osteolysis on AP and lateral films demonstrated a significant difference (AP: Stable 60, Loose 75, p 0.042; LATERAL: Stable 49, Loose73, p 0.016). Diagnostic criteria of fifty percent shell circumference associated with osteolysis on AP films has sensitivity 1, specificity 0.27 while the same criteria on lateral films has sensitivity 0.84, specificity 0.54 for shell loosening. Percent of shell circumference with surrounding oste-olysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.
Purpose: To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Hypothesis: Osteolytic areas differ between loose and stable shells.
Our aim was to evaluate the functional outcome of extensile revision knee exposure techniques. 166 revision total knee arthroplasties requiring an extensile exposure with 2 year minimum follow-up were prospectively studied {81 rectus snips (RS), 42 tibial tubercle osteotomies (TTO), and 43 quadriceps turn-downs (QT)}. Patients were clinically evaluated for knee society score, range of motion (ROM) and extensor lag comparing pre-op and 24 month follow-up appointment findings. Radiological evidence of avascular necrosis (AVN) pre &
post operation was recorded. The TTO group was further examined for proximal migration of the tubercle post op. Pre-operative knee motion (75° &
71°) and knee scores (74 &
70) were lower in revision total knee arthroplasties requiring QT &
TTO than those requiring a RS (91° &
84). Post op flexion and knee scores were greater in the RS group (102° &
131) than in the QT (81° &
114) and TTO (84° &
111) groups in whom there was no significant difference. Avascular necrosis of the patella was most commonly seen following QT. In both QT &
TTO groups performing a lateral release was significantly associated with AVN of the patella. Extensor lag (>
10°) was seen only in the QT &
TTO groups (11% &
8%) in whom there was no significant difference. Tubercle escape (>
2mm) in the TTO group was significantly greater (54%) in those where circlage wires only had been used than in those where a proximal transfixation wire was used (11%). In conclusion, both QT &
TTO groups had similarly poor knee scores &
ROM pre &
post operation. AVN of the patella for both groups was similar and significantly associated with performing a lateral release. Finally we would conclude that the use of a through wire significantly reduces tubercle escape in TTO fixation.