Use of Cementless Metaphyseal Fixation in Revision Total Knee Arthroplasty in the United States.

BACKGROUND: Fixation options for revision total knee arthroplasty (rTKA) have expanded and now include cementless metaphyseal fixation. The utilization rates of these implants in the United States are not well known. The purpose of this study was to analyze trends in cementless metaphyseal fixation for rTKA within the American Joint Replacement Registry (AJRR). METHODS: The AJRR was queried for the years 2015-2019 to identify all rTKA with implant data. Trends in the use of cementless sleeves, metaphyseal cones, and any cementless metaphyseal fixation (sleeves + cones) were examined over the study period using logistic regression analysis. RESULTS: Twenty thousand two hundred and eighty rTKA were analyzed. Cementless metaphyseal fixation was used in 16% of rTKA and significantly increased over the study period (14% to 19%, P < .0001). Cementless metaphyseal fixation was more frequently utilized during revision for aseptic loosening than other diagnoses (OR 1.014, 95% CI 1.001-1.027). Cementless sleeve utilization decreased over time (11% to 9%, P = .004), driven by decreased use on the femur (4% to 2%, P < .0001). The use of cones increased significantly over time (3% to 9%, P < .0001), driven by increased use on the tibia (2% to 9%, P < .0001). Cones were 22 times more likely to be utilized on the tibia relative to the femur (P < .0001) and were more likely to be used in revisions for infection (OR 1.103, 95% CI 1.089-1.117) and aseptic loosening (OR 1.764, 95% CI 1.728-1.800). CONCLUSION: Cementless metaphyseal fixation has grown in popularity yet, still comprised only 16% of rTKA over a 5-year period. Most of the increase was due to the utilization of tibial metaphyseal cones.

Frailty Is Associated With Increased 30-Day Adverse Events and Hospitalization Costs After Primary Total Hip Arthroplasty.

BACKGROUND: Frailty can predict adverse outcomes for multiple medical conditions and surgeries but is not well studied in total hip arthroplasty (THA). We evaluate the association between Hospital Frailty Risk Score and postoperative events and costs after primary THA. METHODS: Using the National Readmissions Database, we identified primary THA patients for osteoarthritis, osteonecrosis, or hip fracture from January to November 2017. Using Hospital Frailty Risk Score, we compared 30-day readmission rate, hospital course duration, and costs between frail and nonfrail patients for each diagnosis, controlling for covariates. Thirty-day complication and reoperation rates were compared using univariate analysis. RESULTS: We identified 167,700 THAs for osteoarthritis, 5353 for osteonecrosis, and 7246 for hip fractures. Frail patients had increased 30-day readmission rates (5.3% vs 2.5% for osteoarthritis, 7.1% vs 3.3% for osteonecrosis, 8.4% vs 4.3% for fracture; P < .01), longer hospital course (3.4 vs 1.9 days for osteoarthritis, 4.1 vs 2.1 days for osteonecrosis, 6.3 vs 3.9 days for fracture; P < .01), and increased costs ($18,712 vs $16,142 for osteoarthritis, $19,876 vs $16,060 for osteonecrosis, $22,185 vs $19,613 for fracture; P < .01). Frail osteoarthritis patients had higher 30-day complication (4.4% vs 1.9%; P < .01) and reoperation rates (1.6% vs 0.93%; P < .01). Frail osteonecrosis patients had higher 30-day complication rates (5.3% vs 2.6%; P < .01). Frail hip fracture patients had higher 30-day complication (6.6% vs 3.8%; P < .01) and reoperation rates (2.9% vs 1.8%; P < .01). CONCLUSION: Frailty is associated with increased healthcare burden and postoperative events after primary THA. Further research can identify high-risk patients and mitigate complications and costs.

Total Femur Antibiotic Spacers: Effective Salvage for Complex Periprosthetic Joint Infections.

BACKGROUND: A simultaneous periprosthetic joint infection (PJI) of an ipsilateral hip and knee arthroplasty is a challenging complication of lower extremity reconstructive surgery. We evaluated the use of total femur antibiotic-impregnated polymethylmethacrylate (PMMA) bone cement spacers in the staged treatment of such limb-threatening PJIs. METHODS: Thirteen patients were treated with a total femur antibiotic spacer. The mean age at the time of spacer placement was 65 years. Nine patients had polymicrobial PJIs. All spacers incorporated vancomycin (3.0 g/40 g PMMA) and gentamicin (3.6 g/40 g PMMA), while 8 also included amphotericin (150 mg/40 g PMMA). Eleven spacers were biarticular. Twelve spacers were implanted through one longitudinal incision, while 8 of 12 reimplantations occurred through 2 smaller, separate hip and knee incisions. Mean follow-up after reimplantation was 3 years. RESULTS: Twelve (92%) patients underwent reimplantation of a total femur prosthesis at a mean of 26 weeks. One patient died of medical complications 41 days after spacer placement. At latest follow-up, 3 patients had experienced PJI recurrence managed with irrigation and debridement. One required acetabular component revision for instability. All 12 reimplanted patients retained the total femur prosthesis with no amputations. Eleven (91%) were ambulatory, and 7 (58%) remained on suppressive antibiotics. CONCLUSION: Total femur antibiotic spacers are a viable, but technically demanding, limb-salvage option for complex PJIs involving the ipsilateral hip and knee. In the largest series to date, there were no amputations and 75% of reimplanted patients remained infection-free. Radical debridement, antimicrobial diversity, prolonged spacer retention, and limiting recurrent soft tissue violation are potential tenets of success. LEVEL OF EVIDENCE: IV.

Are Postoperative Hip Precautions Necessary After Primary Total Hip Arthroplasty Using a Posterior Approach? Preliminary Results of a Prospective Randomized Trial.

BACKGROUND: It is unclear whether posterior hip precautions after primary total hip arthroplasty (THA) reduce the incidence of early postoperative dislocation. METHODS: We performed a prospective randomized study to evaluate the effect of hip precautions on incidence of early dislocation after primary THA using a posterior approach. Between January 2016 and April 2019, 587 patients (594 hips) were consented and randomized into restricted or unrestricted groups. No significant demographic or surgical differences existed between groups. The restricted group was instructed to refrain from hip flexion >90°, adduction across midline, and internal rotation for 6 weeks. 98.5% (585 of 594) of hips were available for minimum 6-week follow-up (291 restricted and 294 unrestricted). Power analysis showed that 579 hips per group are needed to demonstrate an increase in dislocation rate from 0.5% to 2.5% with 80% power. RESULTS: At average follow-up of 15 weeks (range, 6-88), there were 5 dislocations (incidence, 0.85%). Three posterior dislocations occurred in the restricted group at a mean of 32 days (range, 17-47), and 2 posterior dislocations occurred in the unrestricted group at a mean of 112 days (range, 21-203), with no difference in dislocation rate between groups (1.03% vs 0.68%; odds ratio, 0.658; 95% confidence interval, 0.11-3.96; P = .647). At 6 weeks, unrestricted patients endorsed less difficulty with activities of daily living, earlier return to driving, and more time spent side sleeping (P < .05). CONCLUSION: Preliminary analysis suggests that removal of hip precautions after primary THA using a posterior approach was not associated with early dislocation and facilitated return to daily functions. Investigation to appropriate power is warranted.

Is There a Benefit to Modularity for Femoral Revisions When Using a Splined, Tapered Titanium Stem?

BACKGROUND: Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs monoblock splined, tapered titanium stems in revision THA. METHODS: We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2-17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included. RESULTS: There were no statistically significant differences in rates of reoperation (22.3% vs 17.9%; P = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .20) between groups. CONCLUSION: Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine whether modularity is beneficial for more complex femoral defects.

Inpatient Versus Outpatient Arthroplasty: A Single-Surgeon, Matched Cohort Analysis of 90-Day Complications.

BACKGROUND: Although some prior work supports the safety of same-day arthroplasty performed in a hospital, concerns remain when these procedures are performed in a free-standing ambulatory surgery center. The purpose of this study is to compare 90-day complication rates between matched cohorts that underwent inpatient vs outpatient arthroplasty at an ambulatory surgery center. METHODS: A single-surgeon cohort of 243 consecutive patients who underwent outpatient arthroplasty was matched with 243 inpatients who had the same procedure. One-to-one nearest-neighbor matching with respect to gender, age, American Society of Anesthesiologists Score, and body mass index was utilized. The 486 primary arthroplasties included 178 unicondylar knees (36.6%), 146 total hips (30.0%), 92 total knees (18.9%), and 70 hip resurfacings (14.5%). Ninety-day outcomes including reoperation, readmission, unplanned clinic or emergency department visits, and major and minor complications were compared using a 2-sample proportions test. RESULTS: The 2 cohorts were similar in distribution of demographic variables, demonstrating successful matching. The inpatient and outpatient cohorts both had readmission rates of 2.1% (P = 1.0). With the number of subjects studied, there were no statistically significant differences in rates of major complications (2.1% vs 2.5%, P = 1.0), minor complications (7.0% vs 7.8%, P = .86), reoperations (0.4% vs 2.1%, P = .22), emergency department visits (1.6% vs 2.5%, P = .52), or unplanned clinic visits (3.3% vs 5.8%, P = .19). CONCLUSION: This study suggests that arthroplasty procedures can be performed safely in an ambulatory surgery center among appropriately selected patients without an increased risk of complications.

Short-term Complications After Revision Hip Arthroplasty for Prosthetic Joint Infection Are Increased Relative to Noninfectious Revisions.

BACKGROUND: Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) is associated with significant morbidity and cost. The purpose of this study was to determine how rates of perioperative complications, operative duration, and postoperative length of stay (LOS) in patients undergoing revision THA for PJI compare to primary THA and to revision THA for non-PJI. METHODS: We used the National Surgical Quality Improvement Program registry from 2005 to 2015 to identify all patients who underwent primary and revision THA. Patients were placed into cohorts based on the surgical procedure and by indication, including (1) primary THA, (2) revision THA for PJI, and (3) revision THA for non-PJI. Differences in 30-day postoperative medical complications, hospital readmissions, operative duration, and LOS were compared using bivariate and multivariate analyses. RESULTS: One lakh fourteen thousand five hundred five THA patients were identified, with 102,460 (89.5%) patients undergoing a primary THA and 12,045 (10.5%) undergoing a revision procedure. Of the 12,045 revision procedures, 10,777 (89.5%) were for non-PJI indications and 1268 (10.5%) were for PJI. Relative to primary THA, patients undergoing revision THA for PJI had an increased rate of total complications (odds ratio [OR] 3.96), sepsis (OR 13.15), deep surgical site infections (SSIs, OR 8.58), superficial SSI (OR 2.14, P = .002), nonhome discharge (OR 1.85), readmissions (OR 2.46), LOS (+3.0 days), and operative duration (+61 minutes). Compared with non-PJI revisions, PJI revisions had an increased rate of total complications (OR 2.42), sepsis (OR 5.51), deep SSI (OR 2.12), nonhome discharge (OR 1.47), and LOS (+1.8 days). CONCLUSION: Revision THA for PJI is associated with increased postoperative complications, nonhome discharge, and LOS relative to non-PJI revision THA. Separate care pathways and reimbursement bundles should be considered for patients with PJI. LEVEL OF EVIDENCE: III.

A Prospective Randomized Trial of Mini-Incision Posterior and 2-Incision Total Hip Arthroplasty: Minimum 5-Year Follow-Up.

BACKGROUND: We previously described the results of a randomized controlled trial of mini-posterior vs 2-incision total hip arthroplasty and were unable to demonstrate significant differences in early outcomes. As less-invasive anterior approaches remain popular, the purpose of this report was to re-examine the outcomes at a minimum 5-year follow-up. METHODS: Seventy-two patients undergoing primary total hip arthroplasty were randomized to a mini-posterior or 2-incision approach. Complications, revisions, and clinical outcome measures were compared. Radiographs were reviewed for implant loosening. A power analysis using a minimal clinically important difference value of 6 points for the Harris hip score revealed 28 patients required per group. RESULTS: At a mean of 8.2 years (range, 5-10 years), 6 patients died without revision surgery and 63 of 66 living patients were reviewed. There were 6 total failures, 3 in each group. For unrevised patients, there were no significant differences between groups (posterior vs 2-incision) in the Harris hip score (95.5 ± 3.5 vs 95.7 ± 6.3; P = .88), 12-item Short Form Survey physical composite score (50.5 ± 8.5 vs 49.0 ± 9.1; P = .53), 12-item Short Form Survey mental composite score (57.3 ± 4.1 vs 55.4 ± 8.0; P = .25), or single assessment numeric evaluation score (97.1 ± 3.7 vs 97.8 ± 5.2; P = .55). CONCLUSION: We found no differences in midterm outcomes between the 2 approaches. Given the increased complexity, operative time, and need for fluoroscopy with the 2-incision approach combined with equivalent early and midterm outcomes, the 2-incision approach has been abandoned in the senior author's practice.

Sepsis Within 30 Days of Geriatric Hip Fracture Surgery.

BACKGROUND: Sepsis after hip fracture typically develops from one of the 3 potential infectious sources: urinary tract infection (UTI), pneumonia, and surgical site infection (SSI). The purpose of this investigation is to determine (1) the proportion of cases of sepsis that arises from each of these potential infectious sources; (2) baseline risk factors for developing each of the potential infectious sources; and (3) baseline risk factors for developing sepsis. METHODS: The National Surgical Quality Improvement Program database was searched for geriatric patients (aged >65 years) who underwent surgery for hip fracture during 2005-2013. Patients subsequently diagnosed with sepsis were categorized according to concomitant diagnosis with UTI, SSI, and/or pneumonia. Multivariate regression was used to test for associations while adjusting for baseline characteristics. RESULTS: Among the 466 patients who developed sepsis (2.4% of all patients), 157 (33.7%) also had a UTI, 135 (29.0%) also had pneumonia, and 36 (7.7%) also had SSI. The rate of sepsis was elevated in patients who developed UTI (13.0% vs 1.7%; P < .001), pneumonia (18.2% vs 1.8%; P < .001), or SSI (14.8% vs 2.3%; P < .001). The mortality rate was elevated among those who developed sepsis (21.0% vs 3.8%; P < .001). CONCLUSION: Sepsis occurs in about 1 in 40 patients after geriatric hip fracture surgery. Of these septic cases, 1 in 3 is associated with UTI, 1 in 3 with pneumonia, and 1 in 15 with SSI. The cause of sepsis is often unknown on clinical diagnosis, and this distribution of potential infectious sources allows clinicians for direct identification and treatment.

What Factors Influence the Success of Medial Gastrocnemius Flaps in the Treatment of Infected TKAs?

BACKGROUND: Soft tissue defects after TKA are a potentially devastating complication. Medial gastrocnemius flaps occasionally are used to provide soft tissue coverage, most commonly with a periprosthetic joint infection. QUESTIONS/PURPOSES: We asked: (1) What were the rates of persistent or recurrent infection, implant survivorship, flap-related complications, and reoperation for patients who underwent medial gastrocnemius flap reconstruction for soft tissue coverage after TKA? (2) What were the Knee Society clinical and functional scores for patients who underwent medial gastrocnemius flap reconstruction for soft tissue defects after TKA? (3) What were the risk factors for failure of medial gastrocnemius flap reconstruction after TKA, with failure defined as recurrent or new periprosthetic joint infection or inability to reimplant the TKA prosthesis? METHODS: Between 2003 and 2011, four surgeons at one institution performed 31 medial gastrocnemius flaps for soft tissue coverage over an infected TKA. Of those, 27 (87%) were available for followup at a minimum of 2 years (mean, 4 years; range, 2-6 years), although patients experiencing complications or treatment failures before two years were included. The study group consisted of 15 men and 12 women with a mean age of 61 years at the time of surgery (range, 36-86 years). The general indication for using a gastrocnemius flap in this setting was full-thickness soft tissue deficiency over the anterior knee during the course of treatment for concomitant deep infection. Six flaps were performed at prosthetic explantation and antibiotic spacer placement, eight at a spacer exchange, eight at second-stage TKA prosthesis reimplantation, and five at débridement with polyethylene exchange. The decision regarding when during staged treatment to place the flap was based solely on when the soft tissues were deemed insufficient, and not based on a belief that placement at one stage versus another was advantageous. Failure was defined as inability to undergo reimplantation of a TKA prosthesis or recurrence of periprosthetic joint infection. Patient and procedural characteristics were tested for association with failure. Survivorship was calculated by Cox proportional hazards modeling. Outcomes scores were drawn from a longitudinal institutional registry. RESULTS: Fourteen of 27 (52%) patients had a persistent or recurrent infection; survivorship of the TKA prosthesis at 4 years was 48% (95% CI, 31%-66%). Although there were no flap-related complications, 12 patients had a total of 19 reoperations during the study period. Overall, the mean (± SD) Knee Society knee (38 ± 18 vs 65 ± 20; p < 0.001) and function (20 ± 22 vs 37 ± 25; p = 0.002) scores were improved at most recent followup. No factors were identified as associated with failure when a Bonferroni correction was applied. CONCLUSIONS: Gastrocnemius flaps were used to address difficult soft tissue defects in this series, in the presence of deep infections; the high proportion of patients experiencing persistent or recurrent infections reflects the case complexity and not necessarily a problem with the flaps. However, this series highlights the need to continue to explore alternative approaches to managing this difficult clinical problem. Future studies should aim to establish an evidence-based reconstructive algorithm, focusing on host, wound, and timing characteristics that may maximize outcomes. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Is There a Benefit to Modularity in 'Simpler' Femoral Revisions?

BACKGROUND: Modular revision femoral components allow the surgeon to make more precise intraoperative adjustments in anteversion and sizing, which may afford lower dislocation rates and improved osseointegration, but may not offer distinct advantages when compared with less expensive monoblock revision stems. QUESTIONS/PURPOSES: We compared modular and monoblock femoral components for revision of Paprosky Type I to IIIA femoral defects to determine (1) survivorship of the stems; and (2) complications denoted as intraoperative fracture, dislocation, or failure of osseointegration. METHODS: Between 2004 and 2010, participating surgeons at three centers revised 416 total hip arthroplasties (THAs) with Paprosky Type I to IIIA femoral defects. Of those with minimum 2-year followup (343 THAs, mean followup 51 ± 13 months), 150 (44%) were treated with modular stems and 193 (56%) were treated with monoblock, cylindrical, fully porous-coated stems. During this time, modular stems were generally chosen when there was remodeling of the proximal femur into retroversion and/or larger canal diameters (usually > 18 mm). A total of 27 patients died (6%) with stems intact before 2 years, 46 THAs (13%) were lost to followup before 2 years for reasons other than death, and there was no differential loss to followup between the study groups. The modular stems included 101 with a cylindrical distal geometry (67%) and 49 with a tapered geometry (33%). Mean age (64 versus 68 years), percentage of women (53% versus 47%), and body mass index (31 versus 30 kg/m(2)) were not different between the two cohorts, whereas there was trend toward a slightly greater case complexity in the modular group (55% versus 65% Type 3a femoral defects, p = 0.06). Kaplan-Meier survivorship was calculated for the endpoint of aseptic revision. Proportions of complications in each cohort (dislocation, intraoperative fracture, and failure of osseointegration) were compared. RESULTS: Femoral component rerevision for any reason (including infection) was greater (OR, 2.01; 95% CI, 1.63-2.57; p = 0.03) in the monoblock group (27 of 193 [14%]) compared with the modular cohort (10 of 150 [7%]). Femoral component survival free from aseptic rerevision was greater in the modular group with 91% survival (95% CI, 89%-95%) at 9 years compared with 86% survival (95% CI, 83%-88%) for the monoblock group in the same timeframe. There was no difference in the proportion of mechanically relevant aseptic complications (30 of 193 [16%] in the monoblock group versus 34 of 150 [23%] in the modular group, p = 0.10; OR, 1.47; 95% CI, 0.86-2.53). There were more intraoperative fractures in the modular group (17 of 150 [11%] versus nine of 193 [5%]; OR, 2.2; 95% CI, 1.68-2.73; p = 0.02). There were no differences in the proportions of dislocation (13 of 193 [7%] monoblock versus 14 of 150 [9%] modular; OR, 0.96; 95% CI, 0.67-1.16; p = 0.48) or failure of osseointegration (eight of 193 [4%] monoblock versus three of 150 [2%] modular; OR, 1.92; 95% CI, 0.88-2.84; p = 0.19) between the two groups with the number of hips available for study. CONCLUSIONS: Although rerevisions were less common in patients treated with modular stems, aseptic complications such as intraoperative fractures were more common in that group, and the sample was too small to evaluate corrosion-related or fatigue concerns associated with modularity. We cannot therefore conclude from this that one design is superior to the other. Larger studies and pooled analyses will need to be performed to answer this question, but we believe modularity should be avoided in more straightforward cases if possible. LEVEL OF EVIDENCE: Level III, therapeutic study.

The Chitranjan Ranawat Award: Should prophylactic antibiotics be withheld before revision surgery to obtain appropriate cultures?

BACKGROUND: Preoperative antibiotics are known to be critical for decreasing the risk of periprosthetic joint infection (PJI) in primary THA and TKA. However, antibiotics often are withheld before revision surgery, as there is concern that even a single dose of prophylactic antibiotics may affect intraoperative cultures. QUESTIONS/PURPOSES: In this prospective randomized controlled trial, we determined the effect of a single dose of prophylactic antibiotics on cultures obtained at the time of revision arthroplasty. METHODS: We randomized 65 patients with known PJI after 37 TKAs and 28 THAs at three centers. Patients were included in the trial if they had a culture-positive aspiration and had not taken antibiotics within 2 weeks of the procedure. Patients were randomized to receive prophylactic antibiotics either before the skin incision or after a minimum of three sets of intraoperative cultures were obtained. Preoperative and intraoperative cultures were then compared. Results between patients who did and did not receive antibiotics were compared using an equivalence test for proportion differences (two one-sided t-tests [TOST]) with a 0.2 margin. RESULTS: Intraoperative cultures yielded the same organisms as preoperative cultures in 28 of 34 patients (82%) randomized to receive antibiotics before the skin incision compared to 25 of 31 patients (81%) randomized to receive antibiotics after obtaining operative cultures (statistically equivalent by TOST estimate: p = 0.0290). CONCLUSIONS: In this randomized controlled trial, there was no effect on the results of cultures obtained intraoperatively when prophylactic antibiotics were administered before skin incision. Given the known benefits of prophylactic antibiotics in preventing PJI, preoperative prophylaxis should not be withheld in revision surgery for fear of affecting cultures.

Are short fully coated stems adequate for "simple" femoral revisions?

BACKGROUND: Many studies suggest long femoral components should be used in revision THA. However, longer stems are more difficult to insert and reduce femoral bone stock for future revisions. QUESTIONS/PURPOSES: We investigated (1) how frequently a short (≤ 160-mm or primary-length) fully porous-coated stem could be utilized for Paprosky Type I to IIIA femoral defects, (2) how often the tip of the old stem or cement mantle was bypassed by the revision implant, (3) Harris hip scores, radiographic signs of osseointegration, and revision frequency, and (4) complications associated with these reconstructions. METHODS: Two surgeons performed 277 femoral revisions graded as Paprosky Types I to IIIA between 2004 and 2009. When femoral canal diameter was less than 18 mm, these surgeons generally used the shortest stem capable of achieving a minimum of 4 cm of scratch fit in the femoral isthmus. Patients were evaluated clinically using the Harris hip score and radiographically for component loosening and to determine whether the revision component bypassed the prior stem tip or cement mantle. RESULTS: A short stem was utilized in 144 of the 277 revisions (52%). In 113 (78%), the revision femoral component did not bypass the tip of the prior stem or cement mantle. The Harris hip score improved (p < 0.001) from 36 preoperatively to 76 at a mean of 4 years (range, 2-8 years). Twelve stems required repeat revision including six (4.9%) for failed ingrowth. Complications included four intraoperative fractures, three postoperative femoral fractures, one cortical perforation, and eight dislocations. CONCLUSIONS: Primary-length extensively coated stems provided reliable fixation for ½ of our Paprosky Type I to IIIA femoral revisions. When considering the use of such a component, the revision surgeon should take into account a small risk of failed osseointegration and technical challenges associated with this technique.

Is synovial C-reactive protein a useful marker for periprosthetic joint infection?

BACKGROUND: Serum C-reactive protein (CRP) is a general marker of inflammation, and recent studies suggest that measurement of CRP in synovial fluid may be a more accurate method for diagnosing periprosthetic joint infection (PJI). QUESTIONS/PURPOSES: We aimed to (1) determine if there is a correlation between serum and synovial CRP values, (2) establish cutoff values for diagnosing infection based on serum and synovial CRP, and (3) compare the utility of measuring CRP in synovial fluid versus serum for the diagnosis of PJI using standard assay equipment available at most hospitals. METHODS: Between February 2011 and March 2012, we invited all 150 patients scheduled for revision TKA (84) or THA (66) to participate in this prospective study, of whom 100% agreed. Data ultimately were missing for 31 patients, leaving 60 patients undergoing revision TKA and 59 undergoing revision THA (71% and 89% of the original group, respectively) for whom CRP level was measured in serum and synovial fluid samples. Patients were deemed to have a PJI (32) or no infection (87) using Musculoskeletal Infection Society criteria. Serum and synovial CRP levels were assayed using the same immunospectrophotometer and the correlation coefficient was calculated. Receiver operating characteristic curve analyses were performed to compare utility in diagnosing PJI, which included area under the curve, diagnostic threshold, and test sensitivity, specificity, predictive values, and accuracy. In 22 of 150 patients (14.7%), synovial CRP could not be measured because the sample was too viscous or hemolyzed. RESULTS: In the analyzed 119 samples, there was a strong correlation (r = 0.76; p < 0.001) between synovial and serum CRP. The area under the curve was 0.90 both for the synovial fluid (95% CI, 0.82-0.97) and serum (95% CI, 0.84-0.96) CRP assays. The diagnostic thresholds were 6.6 mg/L for synovial fluid and 11.2 mg/L for serum. Sensitivities, specificities, positive predictive value, negative predictive value, and accuracies were similar for synovial fluid and serum assays. CONCLUSIONS: Although recent studies have suggested a superiority of synovial fluid CRP over serum CRP for the diagnosis of PJI, we found that measurement of CRP in synovial fluid rather than serum using readily available assay equipment does not offer a diagnostic advantage in detection of PJIs. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Instructions to Authors for a complete description of levels of evidence.

Recurrent periprosthetic joint infection: persistent or new infection?

It is unclear if recurrent periprosthetic joint infection (PJI) is a result of failed pathogen eradication. This study addresses this issue. We identified 92 patients from three institutions who failed two-stage exchange. Cultured organisms at each stage of treatment were compared to determine whether these were persistent or new infections. Only twenty-nine of the 92 patients (31.5%) had identical organisms at treatment failure. Of the failures associated with Staphylococcus as the original infecting organism, 37% (25 of 67) failed due to the same organism compared to only 16% (four of 25) caused by other organisms. Positive cultures at reimplantation and poor health status were associated with higher rates of recurrent infection due to new organisms. Successful management of PJI with a two-stage exchange must stress minimization of comorbid risk factors that may contribute to the low success rate of PJI treatment and recurrence of infection.

Should draining wounds and sinuses associated with hip and knee arthroplasties be cultured?

We assessed the utility of culturing draining wounds or sinuses in evaluating periprosthetic joint infection (PJI). Fifty-five patients with a draining wound or sinus after total joint arthroplasty (28 knees, 27 hips) who had not received antibiotics for at least two weeks were prospectively studied. Superficial wound cultures were compared to intra-articular cultures to determine accuracy in isolating infecting organism(s). The superficial cultures were concordant with deep cultures in 26 of 55 cases (47.3%) and were more likely to generate polymicrobial results (27.3% vs. 10.9%; P=0.023). In 23 cases (41.8%), the superficial cultures would have led to a change in antibiotic regimen. Superficial cultures yielded bacterial growth in 8 of the 10 cases (80%) when deep cultures and further work-up suggested the absence of deep infection. Given the potential to misguide diagnosis and treatment, we recommend against obtainment of superficial cultures in patients with a draining wound or sinus following hip or knee arthroplasty.

What is the prevalence of MRSA colonization in elective spine cases?

BACKGROUND: The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection is increasing. However, the prevalence of MRSA colonization among patients undergoing spine surgery is unclear. QUESTIONS/PURPOSES: We therefore (1) determined the prevalence of MRSA colonization in a population of patients scheduled for elective spine surgery; and (2) evaluated whether MRSA screening and treatment reduce the rate of early wound complications. METHODS: We retrospectively reviewed prospectively collected data from 1002 patients undergoing elective spine surgery in 2010. There were 719 primary and 283 revision surgeries. Instrumentation was used in 72.0% cases and autologous iliac crest bone graft was taken in 65.1%. Twelve patients were lost to followup; of the remaining 990 patients, 503 were screened for MRSA and 487 were not. MRSA-colonized patients were treated with mupirocin and chlorhexidine. An early wound complication was defined as wound drainage or the presence of an abscess. Patients were followed for a minimum of 3 months (average, 7 months; range, 3-545 days). RESULTS: Of the patients undergoing elective spine surgery and screened for MRSA, 14 of 503 (2.8%) were colonized with MRSA. The rates of early wound complications were similar for patients who were screened and pretreated for MRSA (17 of 503 [3.4%]) compared with those who were not (17 of 487 [3.5%]). CONCLUSIONS: The colonization rate for MRSA in our elective spine surgery population was comparable to that in the arthroplasty literature. LEVEL OF EVIDENCE: Level III, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

Use of a monoblock dual-mobility acetabular component in primary total hip arthroplasty in patients at high risk of dislocation.

INTRODUCTION: Dislocation is amongst the most common complications following total hip arthroplasty (THA). Dual-mobility bearings have been suggested as one way to reduce the risk of dislocation, particularly among patients at increased risk. The purpose of this study was to determine the outcomes of a monoblock dual-mobility shell for patients at high risk for dislocation following primary THA. METHODS: A total of 155 primary THAs with a monoblock, cementless dual-mobility acetabular component were performed in patients at high risk for dislocation. Two patients died prior to their two-year follow-up. The remaining 153 THAs were followed for a mean of 5.1 years (range: 2.1 to 9.3). RESULTS: There were no dislocations; however, four patients underwent revision surgery: one for an early periprosthetic acetabular fracture, one for an early periprosthetic femoral fracture, one for a late periprosthetic femoral fracture, and one for leg-length discrepancy. Intraoperative complications included one periprosthetic acetabular fracture treated with protected weight-bearing and one intraoperative proximal femoral fracture treated with cerclage wiring. Harris Hip Scores improved from a mean of 42.4 points preoperatively to a mean of 82.4 points postoperatively (p < 0.001). No cups were radiographically loose. At a mean follow-up of 5.1 years, survivorship of the acetabular component was 99.3% (95% CI, 98.1-100%) and survivorship without any reoperation was 97.4% (95% CI, 95.9-100%). DISCUSSION: Although there were no dislocations in this high-risk population, periprosthetic fractures of the femur and acetabulum were common with the implants utilised.

Direct Anterior Approach Total Hip Arthroplasty Is Not Associated with Increased Infection Rates: A Systematic Review and Meta-Analysis.

BACKGROUND: The direct anterior approach (DAA) for primary total hip arthroplasty (THA) has recently increased in popularity. Recent evidence has raised concerns about whether use of the DAA is associated with increased rates of superficial and deep infection. The aim of this study was to systematically assess the literature and comparatively evaluate the rate of superficial and deep infection following primary THA using the DAA and non-direct anterior (non-DAA) approaches. METHODS: This study was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) statement. Primary outcome measures evaluated were rates of superficial and deep infection in patients undergoing DAA and non-DAA primary THA. RESULTS: A total of 1,872 studies were identified in the original search, of which 15 studies satisfied inclusion criteria. Our analysis evaluated 120,910 primary THAs, including 14,908 DAA and 106,002 non-DAA. The rate of superficial infection was 1.08% for DAA compared with 1.24% for non-DAA (odds ratio [OR] = 1.01, 95% confidence interval [CI] = 0.79 to 1.30, p = 0.921). The rate of deep infection was 0.73% for DAA compared with 0.51% for non-DAA (OR = 1.03, 95% CI = 0.80 to 1.32, p = 0.831). CONCLUSIONS: This study found no difference in the rate of superficial or deep infection after primary THA using the DAA versus other surgical approaches. Our results suggest that comparative infection risk need not be a primary driver in the choice of surgical approach. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Isolated tibial insert exchange in revision total knee arthroplasty : reliable and durable for wear; less so for instability, insert fracture/dissociation, or stiffness.

AIMS: This study aimed to determine outcomes of isolated tibial insert exchange (ITIE) during revision total knee arthroplasty (TKA). METHODS: From 1985 to 2016, 270 ITIEs were performed at one institution for instability (55%, n = 148), polyethylene wear (39%, n = 105), insert fracture/dissociation (5%, n = 14), or stiffness (1%, n = 3). Patients with component loosening, implant malposition, infection, and extensor mechanism problems were excluded. RESULTS: Survivorship free of any re-revision was 68% at ten years. For the indication of insert wear, survivorship free of any re-revision at ten years was 74%. Re-revisions were more frequent for index diagnoses other than wear (hazard ratio (HR) 1.9; p = 0.013), with ten-year survivorships of 69% for instability and 37% for insert fracture/dissociation. Following ITIE for wear, the most common reason for re-revision was aseptic loosening (33%, n = 7). For other indications, the most common reason for re-revision was recurrence of the original diagnosis. Mean Knee Society Scores improved from 54 (0 to 94) preoperatively to 77 (38 to 94) at ten years. CONCLUSION: After ITIE, the risk and reasons for re-revision correlated with preoperative indications. The best results were for polyethylene wear. For other diagnoses, the re-revision rate was higher and the failure mode was most commonly recurrence of the original indication for the revision TKA. Cite this article: Bone Joint J 2021;103-B(6):1103-1110.