The Effect of the COVID Pandemic on the Rate of Same-Day Discharge in Primary Hip and Knee Arthroplasty.

BACKGROUND: Same-day discharge (SDD) following primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) started increasing prior to 2020. The purpose of this study was to evaluate the change in the rate of SDD after the pandemic and determine whether those changes became permanent. METHODS: The annual rate of SDD for 15,208 primary THA and TKA cases performed between January 1, 2015, and September 9, 2022, at a single institution was determined. We also examined changes in SDD patient demographics as well as differences in the 90-day complication rates of SDD and overnight patients. RESULTS: In 2015, the rate of SDD for primary arthroplasty was 24%, which grew annually to 29% in 2019. Postpandemic, the rate of SDD jumped above 50% and continued up to 64% by 2022. The biggest increase was in TKA, which went from under 10% SDD prepandemic to 50% by 2022. The average age and body mass index of SDD cases prepandemic increased significantly to 62 ± 9 years and 29.4 ± 5.3 (P < .01). Overnight patients had higher rates of 90-day postoperative complications (8.4 versus 4.2%, P < .00001). CONCLUSIONS: The pandemic caused major changes in the rate of SDD for primary THA and TKA, increasing in subsequent years. The SDD patients became older and heavier due to the expanded criteria for SDD cases. The 90-day postoperative complication rate was lower for SDD patients since higher risk patients were kept overnight. At the prepandemic rate, 29% of patients currently being sent home would have stayed overnight.

Does Powered Femoral Broaching Compromise Patient Safety in Total Hip Arthroplasty?

Background: During manual broaching (MB) in total hip arthroplasty (THA), off-axis forces delivered to the proximal femur and broach malalignment can lead to fractures and cortical perforations. Powered broaching (PB) is a novel alternative that delivers consistent impaction forces and reduces workload. This is the first large-scale study to compare intraoperative and 90-day rates of periprosthetic femur fractures (PFFs) and perforations in THA performed using MB vs PB. Methods: Our institutional database was reviewed for all patients undergoing primary cementless direct anterior THA from 2016 to 2021. Three surgeons performing 2048 THAs (MB = 800; PB = 1248) using the same stem design were included. PFFs and perforations within 90 days of the index procedure were compared. Differences in length of surgery and demographics were assessed. Results: Calcar fractures occurred in <1% of patients (PB [0.96%, 12/1248] vs MB [0.25%, 2/800]; P = .06). Rates of trochanteric fractures did not differ (PB = 0.32% [4/1248] vs MB = 0.38% [3/800]; P = .84). Cortical perforations occurred in 0.24% (3/1248) of the PB cohort and in 0.75% (6/800) of the MB cohort (P = .09). No revisions due to aseptic loosening or PFF occurred within 120 days of surgery. Conclusions: Our single-center experience with powered femoral broaching in THA demonstrates PB is a safe and efficient means of performing direct anterior THA. Low rates (<1%) of PFF, perforation, and revision can be achieved. Given our positive experience with PB, all surgeon authors utilize PB nearly exclusively for elective primary direct anterior THA.

Spinal Anesthesia for Primary Hip and Knee Arthroplasty: Comparative Rates of Transient Neurological Symptoms and Urinary Retention Using Lidocaine, Mepivacaine, and Bupivacaine.

BACKGROUND: Short-acting spinal anesthetics enable rapid recovery after hip and knee arthroplasty; however, concerns with transient neurological symptoms (TNS) cause some to avoid using lidocaine. Postoperative urinary retention (POUR) is also a concern with spinal anesthesia. We sought to study the comparative rates of TNS and POUR between lidocaine, mepivacaine, and bupivacaine in a high-volume hip and knee arthroplasty setting. METHODS: Data for 1,217 primary THA, TKA, and unicompartmental knee arthroplasty cases were reviewed and grouped by spinal anesthetic agent (lidocaine, mepivacaine, or bupivacaine). Of the 1,217 cases, utilization was 523 lidocaine, 573 mepivacaine, and 121 bupivacaine. The incidence of TNS and POUR requiring catheterization was measured both by clinical evaluation as well as a questionnaire sent to patients 14 days postoperatively. RESULTS: The overall rate of TNS was 8%. With the numbers available, there was no difference in rates of TNS between groups (6.9% lidocaine, 9.2% mepivacaine, and 4.1% bupivacaine; P = .297). There was no difference in rates of TNS or POUR between THA and TKA/unicompartmental knee arthroplasty. Bupivacaine had a significantly higher rate of urinary retention (9.1%; P < .001) than mepivacaine (2.8%) or lidocaine (1.5%). CONCLUSION: This study showed no difference in the rate of TNS between the 3 common agents used in spinal anesthesia. Short-acting spinal anesthetics such as lidocaine and mepivacaine can lower the rate of POUR requiring catheterization, helping to enable rapid recovery after hip and knee arthroplasty.

Early Results of a Randomized Controlled Trial of Partial Versus Total Knee Arthroplasty.

BACKGROUND: Debate still exists regarding the benefits of unicompartmental (UKA) versus total knee arthroplasty (TKA) for the treatment of medial compartment osteoarthritis. The purpose of this randomized trial is to compare the early outcomes of UKA versus TKA. METHODS: One-hundred and seven candidates for UKA were randomized at two centers; 57 candidates received UKA and 50 received TKA. Six-week and 6-month outcome measures including Knee Injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS, JR), Knee Society Score (KSS), Forgotten Joint Score (FJS), and VR-12 global health scores were obtained. No demographic or baseline patient reported outcome (PRO) differences were present suggesting successful randomization (P > .05). RESULTS: UKA demonstrated shorter operative times (UKA = 65 minutes, TKA = 74 minutes; P < .001) and length of stay (UKA = 0.7 nights, TKA = 1.2 nights; P < .01). At 6 weeks, there were no differences in KOOS, JR (P = .755), KSS (P = .754), FJS (P = .664), or PRO change from preoperative scores (P = .468). There were three surgical complications within 90 days in each group. The duration of opioid consumption (UKA = 33.8 days, TKA = 28.5 days; P = .290) and return to work (UKA = 57.1 days, TKA = 47.3 days; P = .346) did not differ between groups. CONCLUSION: Data suggest no clinically significant differences between UKA and TKA in the early postoperative period in regards to patient-reported outcome measures, duration of opioid use, or return to work. Patients undergoing UKA can anticipate a shorter length of stay and greater early range of motion. All-cause short-term complications may be more prevalent with TKA.

Prospective Randomized Study Using Pharmacogenetics to Customize Postoperative Pain Medication Following Hip and Knee Arthroplasty.

BACKGROUND: The purpose of this study is to determine whether pharmacogenetic testing could be used to effectively customize postoperative pain medicine following total joint replacement. METHODS: Buccal swabs were collected preoperatively from 107 patients. Pharmacogenetic testing was performed for genetic variants on a panel of 16 genes, including CYP2D6, CYP2C9, OPRM1, and CYP1A2, which affect the pharmacodynamics and pharmacokinetics of non-steroidal anti-inflammatory drugs and many opioids. Patients were randomized to a control group or custom group and blinded to their group. The control group was prescribed oxycodone, tramadol, and celecoxib for postoperative pain management. If any of those were not normally metabolized, they were not prescribed to the patients in the custom group, who were given an alternative drug (hydromorphone for narcotics, meloxicam for non-steroidal anti-inflammatory drugs). Patients recorded their pain level (0-10 numeric scale) and all medications taken daily for the first 10 days following surgery. Medication was converted to milligram morphine equivalents (MMEs). RESULTS: Genetic variations to medications in our standard postoperative pain management protocol occurred in 24 of the 107 patients (22.4%). The 10-day MME consumed by patients in the control group with genetic variants was 162.6 mg. Patients with variants who had custom postoperative medication consumed only 86.7 MME in the same timeframe (P = .126). The control group demonstrated a higher 10-day average pain level of 4.2 vs the custom group pain level of only 3.1 (P < .05). CONCLUSION: With custom postoperative pain prescriptions based on pharmacogenetic testing, patients were able to achieve lower pain levels while reducing the consumption of pain medication.

Does Approach Influence the Dislocation Rate Following Head and Liner Exchange in Revision Hip Arthroplasty?

BACKGROUND: Revision total hip arthroplasty with modular component exchange can limit morbidity by retaining well-fixed components but dislocation has been a relatively frequent postoperative complication. This study evaluated the effect of surgical approach on dislocation rate in a modern revision cohort. METHODS: From 2010 to 2020, 248 aseptic head and liner exchanges were performed at a single institution. The mean patient age at revision was 64.9 ± 10.4 years and 50% (123/248) were performed among males. Indications for revision included 140 (56%) for polyethylene wear, 68 (27%) for failed metal-on-metal components, and 40 (16%) for instability. The mean follow-up after revision was 2.3 years. RESULTS: Thirty (12%) hips dislocated at a mean of 0.6 years (range 0.01-4.6) postoperatively. The dislocation rate by revision approach was 17% (9/54) for the direct anterior, 6% (5/80) for the direct lateral, and 14% (16/114) for the posterolateral approach (P = .13). Hips revised by the direct anterior approach that dislocated were more abducted (51 ± 8 vs 45 ± 8, P = .05) and more anteverted (26 ± 9 vs 20 ± 7, P = .04) than non-dislocators. Among all 248 hips, cups with more than 48° of abduction were 2.6 times more likely to dislocate (P = .01). Head diameter, neck length, patient age, and gender were not associated with dislocation (P ≥ .20). CONCLUSION: Dislocation remains a common complication after head and liner exchange regardless of approach. Cup position is associated with postoperative instability and must be critically evaluated during preoperative planning.

Direct Anterior Approach for Primary Total Hip Arthroplasty Lowers the Risk of Dislocation Compared to the Posterior Approach: A Single Institution Experience.

BACKGROUND: One purported benefit of the direct anterior approach (DAA) for total hip arthroplasty (THA) is a lower rate of postoperative dislocation. METHODS: An institutional database was used to identify 8840 primary THAs performed from 2003 to 2020 including 5065 (57%) performed using the DAA and 3775 (43%) performed via the posterior approach (PA). Direction and mechanism of dislocation were determined from chart review. Outcomes were compared using Kaplan-Meier survivorship with dislocation as the endpoint and a Cox multivariate regression was used to investigate factors associated with dislocation. The mean follow-up was 1.7 ± 2.0 years for the DAA and 3.1 ± 3.3 years for the PA. RESULTS: The 0.5% (26/5065) incidence of dislocation among DAA hips was significantly less than the 3.3% (126/3775) among PA cases (P < .001). The majority of dislocations were posterior (DAA 57%, PA 79%) and occurred during activities of daily living (DAA 82%, PA 77%). Five-year survivorship was significantly higher for the DAA group compared to the PA group (99.1% vs 95.4%, P < .001). Dislocation risk was 4.9 times higher for the PA compared to the DAA (hazard ratio = 4.9, 95% confidence interval = 3.2-7.5, P < .001). Increasing head diameter reduced the risk (hazard ratio = 0.70, 95% confidence interval = 0.57-0.86, P < .001). The 0.2% incidence (10/5065) of revision for instability among the DAA group was significantly lower than the 1.1% (43/3775) rate for the PA group (P < .001). CONCLUSION: Compared to primary THAs performed with the PA, DAA cases had a lower risk of dislocation, higher survivorship with dislocation as an endpoint, and a lower risk of revision for instability in this single institution cohort.

Effect of a Clean Surgical Airflow Layer on the Incidence of Infection in Total Hip Arthroplasty.

The Center for Health Design estimates that more than 30% of surgical site infections are caused by airborne pathogens. A device that creates a localized clean air field directly adjacent to and surrounding the incision site is meant to shield a surgical site from particulate in the operating room. The purpose of this study was to determine whether the routine use of this device would reduce the rate of infection following total hip arthroplasty (THA). The authors conducted a retrospective review of primary THA cases performed with and without the airflow device. Since July 2013, a total of 1093 primary THA cases were performed with the device at the authors' institution. The incidence of wound dehiscence and deep infection was compared with that of 1171 THA cases performed prior to July 2013 without the airflow device. There were no significant differences between the study groups regarding average patient age, sex, body mass index, or diagnosis. In the airflow group, there were 7 (0.64%) deep infections and 5 (0.46%) cases of wound dehiscence that required a return to the operating room for irrigation and wound revision. In the control group, there were 7 (0.60%) cases of deep infection and 4 (0.34%) wound revisions. The groups were not significantly different in the rates of infection (P=1.0) or wound revision (P=.75). Both groups had a very low incidence of infection and wound revision, with rates below 1%. Despite compelling bench data showing a dramatic reduction of particle load in the wound, the use of the airflow device did not reduce the clinical rate of infection over a large number of cases. [Orthopedics. 2020;43(5):e425-e430.].

Using pharmacogenetics to structure individual pain management protocols in total knee arthroplasty.

AIMS: The purpose of this study was to use pharmacogenetics to determine the frequency of genetic variants in our total knee arthroplasty (TKA) patients that could affect postoperative pain medications. Pharmacogenetic testing evaluates patient DNA to determine if a drug is expected to have a normal clinical effect, heightened effect, or no effect at all on the patient. It also predicts whether patients are likely to experience side effects from medicine. We further sought to determine if changing the multimodal programme based on these results would improve pain control or reduce side effects. METHODS: In this pilot study, buccal samples were collected from 31 primary TKA patients. Pharmacogenetics testing examined genetic variants in genes OPRM1, CYP1A2, CYP2B6, CYP2C19, CYP3A4, CYP2C9, and CYP2D6. These genes affect the pharmacodynamics and pharmacokinetics of non-steroidal anti-inflammatory drugs and opioids. We examined the frequency of genetic variants to any of the medications we prescribed including celecoxib, hydrocodone, and tramadol. Patients were randomized to one of two groups: the control group received the standard postoperative pain regimen, and the study group received a customized regimen based on the pharmacogenetic results. For the first ten postoperative days, patients recorded pain scores, medication, and side effects. RESULTS: Genetic variants involving one or more medications in the multimodal pain protocol occurred in 13 of the 31 patients (42%). In total, eight patients (26%) had variants affecting more than one of the medications. For the 25 patients who recorded pain and medication logs, the mean pain levels and morphine equivalents (MEQs) consumed in the first ten days were higher in the control group than in the custom-guided group (p = 0.019 for pain and p = 0.655 for MEQ). CONCLUSION: Overall, 42% of patients had a variant involving one of the pain medications prescribed in our perioperative pain program for TKA. Ongoing research will help determine if using these data to modify a patient's medication will improve outcomes. Cite this article: Bone Joint J 2020;102-B(6 Supple A):73-78.

A lower threshold for revision of aseptic unicompartmental vs total knee arthroplasty.

AIMS: It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee arthroplasty (TKA) because conversion surgery to a primary TKA is a less complicated procedure. The purpose of this study was to determine if there is a lower threshold for revising a UKA compared with TKA based on Oxford Knee Scores (OKSs) and range of movement (ROM) at the time of revision. METHODS: We retrospectively reviewed 619 aseptic revision cases performed between December 1998 and October 2018. This included 138 UKAs that underwent conversion to TKA and 481 initial TKA revisions. Age, body mass index (BMI), time in situ, OKS, and ROM were available for all patients. RESULTS: There were no differences between the two groups based on demographics or time to revision. The top reasons for aseptic TKA revision were loosening in 212 (44%), instability in 88 (18%), and wear in 69 (14%). UKA revision diagnoses were primarily for loosening in 50 (36%), progression of osteoarthritis (OA) in 50 (36%), and wear in 17 (12%). Out of a maximum 48 points, the mean OKS of the UKAs before revision was 23 (SD 9.3), which was significantly higher than the TKAs at 19.2 (SD 9.8; p < 0.001). UKA patients scored statistically better on nine of the 12 individual OKS questions. The UKA cases also had a larger pre-revision mean ROM (114°, SD 14.3°) than TKAs (98°, SD 25°) ; p < 0.001). CONCLUSION: At revision, the mean UKA OKSs and ROM were significantly better than those of TKA cases. This study suggests that at our institution there is a difference in preoperative OKS between UKA and TKA at the time of revision, demonstrating a revision bias. Cite this article: Bone Joint J 2020;102-B(6 Supple A):91-95.

Does a "July Effect" Exist for Fellowship Training in Total Hip and Knee Arthroplasty?

BACKGROUND: The hypothetical association between health-care errors and the transition of the medical academic year has been termed the "July effect." Data supporting its existence are conflicting, particularly in orthopedic surgery, and prior studies have inappropriately grouped fellows with resident trainees. No studies to date have examined whether a training initiation effect exists among surgical fellows in adult reconstructive orthopedics. METHODS: This is a level IV retrospective cohort study reviewing 15,650 primary hip and knee arthroplasties performed from 2006 to 2016 at a single institution. Forty arthroplasty fellows were trained during this 10-year period. Primary outcome measures included intraoperative complications, additional procedures, revisions, and nonoperative complications within 90 days of surgery. These complication rates were analyzed by quarter of academic year and by temporal progression through three-month fellowship rotations. RESULTS: There were no differences in intraoperative complication, revision, or nonoperative complication rates between any academic quarter. There was a single statistically lower rate of additional procedures in the third quarter (1.2%) than in the fourth quarter (1.8%, P = .04). The most common complication in this subset was wound dehiscence for patients undergoing hip arthroplasty and stiffness for patients undergoing knee arthroplasty. There was no difference in complication rates during the first, second, or third month as fellows progressed through a single rotation. CONCLUSION: This study does not support the existence of a training-initiation effect among fellows in adult hip and knee reconstruction. Graduated autonomy can be safely employed in a fellowship program without negatively impacting patient outcomes, ensuring the continued high-caliber training of future surgeons.

A Prospective, Randomized Study of Surgical Positioning Software Shows Improved Cup Placement in Total Hip Arthroplasty.

Several technologies are available to assist surgeons with acetabular component positioning in total hip arthroplasty. The purpose of this study was to determine whether surgical positioning software would improve cup position compared with fluoroscopy. This prospective, randomized study compared 200 primary total hip arthroplasty cups placed with and without surgical positioning software. All cases were performed by a single surgeon using the direct anterior approach with fluoroscopy. The target abduction and anteversion angles were set at 40° and 20°, respectively, and measured postoperatively. Cup placement time, total fluoroscopy time, and cup position were compared between groups. Mean abduction was 40.4° (range, 32.7°-49.0°) in the software group compared with 42.3° (range, 33.7°-51.1°) in the control group. The cups placed using software were significantly closer to the target abduction angle (P<.001) with fewer outliers. Mean anteversion was 20.8° (range, 11.2°-31.7°) in the software group compared with 21.8° (range, 11.3°-34.3°) in the control group (P=.063). Eighty-seven percent of cups in the software group fell within 5° of the abduction target, compared with only 68% in the control group (P<.01). Cup placement took longer in the software group (7:04 minutes vs 4:58 minutes, P<.001), and 2 seconds more total fluoroscopy time was used in that group as well (12.9 seconds vs 11.1 seconds, P<.001). The software improved both the accuracy and the precision of cup placement, with only modest increases in surgical time and fluoroscopy time. [Orthopedics. 2019; 42(1):42-47.].

The Lawrence D. Dorr Surgical Techniques & Technologies Award: "Running Two Rooms" Does Not Compromise Outcomes or Patient Safety in Joint Arthroplasty.

BACKGROUND: Scrutiny from the federal government and the media regarding the safety of 1 surgeon doing cases in 2 operating rooms (ORs) on the same day, prompted us to examine our own institutional data. Over the past 11 years, surgeons at our facility have operated consecutively in 1 OR on a given day or used 2 alternating ORs. This study compares these cases with a focus on revisions and complications in both groups. METHODS: Six surgeons performed a total of 16,916 primary hip and knee arthroplasties from 2006-2016. 7002 cases (41%) were consecutive cases (CCs) and 9914 cases (59%) were overlapping cases (OCs). Intraoperative complications, component revisions, and postoperative complications within 90 days of surgery were compared between the CC and OC groups. RESULTS: There was no difference in intraoperative complication rates between the two groups (CC 1.6% vs. OC 1.7%, relative risk 1.082, 95% confidence interval 0.852 to 1.375, P = .52). There was no difference in 90-day component revision rates among the CC and OC groups (0.66% vs. 0.85% respectively, relative risk = 1.290, 95% confidence interval 0.901 to 1.845, P = .19). There was also no difference in 90-day complication rates among the CC and OC groups (1.33% vs. 1.45% respectively, relative risk = 1.094, 95% confidence interval 0.844 to 1.417, P = .54). CONCLUSION: This large study of a single institution with multiple surgeons over an 11-year period shows no compromise in patient safety or outcomes when comparing cases done in either consecutive or overlapping rooms.

Operating room traffic in total joint arthroplasty: Identifying patterns and training the team to keep the door shut.

BACKGROUND: Surgical site infections after joint arthroplasty are devastating complications and are influenced by patient, surgical, and operating room environmental factors. METHODS: In an effort to reduce the incidence of door openings (DOs) during total joint arthroplasty cases, this prospective observational study consisted of 3 phases. Phase 1 determined the baseline incidence of DOs, followed by installation of a mechanical door counter (phase 2). Finally, an educational seminar was presented to all personnel (phase 3) regarding the implications frequent DOs have on patient and surgical outcomes. RESULTS: The average openings per case (OPC) for each of the 3 phases were 33.5, 34.2, and 27.7, respectively. There was a 17% reduction in OPC between phases 1 and 3 (P= .02). There were no significant differences between knee and hip arthroplasty cases during the 3 phases (P= .21, P= .46, and P= .81, respectively). There was a strong correlation between length of surgery and OPC, with a Pearson coefficient of r = 0.87 during phase 3. To account for differences in average operative time between phases, data were normalized for the length of surgery with the ratio of door openings per minute determined (0.36, 0.34, and 0.32 for each phase, respectively). CONCLUSIONS: We were able to show that simply monitoring door openings during joint arthroplasty was not effective in reducing the occurrences. However, after a novel educational seminar given to all personnel, we were able to significantly reduce the incidence of operating room door openings, reducing a potential risk factor for surgical site infections.

Comparison of Wound Complications and Deep Infections With Direct Anterior and Posterior Approaches in Obese Hip Arthroplasty Patients.

BACKGROUND: The purpose of this study was to compare the posterior approach (PA) with the direct anterior approach (DAA) among obese and nonobese total hip arthroplasty patients to determine if obese DAA patients have a higher risk of infection or wound complications compared with obese PA patients. METHODS: We retrospectively evaluated 4651 primary total hip cases performed via anterior approach or PA between 2009 and 2015. Patients were divided into 4 study groups based on approach and body mass index (BMI): (1) DAA <35 kg/m2, (2) DAA ≥35 kg/m2, (3) PA <35 kg/m2, and (4) PA ≥35 kg/m2. Infection rates and wound complications were compared. RESULTS: The rate of deep infection in groups 1 and 3 (nonobese anterior vs posterior) was 0.28% and 0.36%, respectively (P = .783); and in groups 2 and 4 (obese anterior vs posterior) was 2.35% and 2.7%, respectively (P = .80). The rate of wound complications between groups 1 and 3 (nonobese) was 1.0% and 0.3%, respectively (P = .005). Between groups 2 and 4 (obese), the rates of complications were 1.7% and 1.4%, respectively (P = 1.0). There was no difference in reoperation rates for wounds between groups 1 and 3 or between groups 2 and 4 (P = .217, P = .449). CONCLUSION: In the largest available series, there was no difference in deep infection rates between the 2 approaches. In the subset of obese patients with BMI ≥35 kg/m2, there was no increased risk of deep infection or wound complications in DAA patients compared with PA patients. However, anterior hip cases experienced higher rates of superficial wound complications compared with posterior cases across all BMIs.

Perioperative Pain Management and Anesthesia: A Critical Component to Rapid Recovery Total Joint Arthroplasty.

Multimodal pain management has become the standard of care following total hip and knee replacement. The advantages include decreasing opioid consumption and its associated side effects, facilitating earlier mobilization, and faster return to function. An effective rapid recovery protocol includes the use of multiple different types of medications targeting each area of the pain pathway, preemptive analgesia, regional nerve blockade, and local infiltration analgesia.

Intraoperative fluoroscopy with a direct anterior approach reduces variation in acetabular cup abduction angle.

INTRODUCTION: The purpose of this study was to compare acetabular cup position for 2 cohorts of total hip arthroplasty (THA) patients who had a direct anterior approach. METHODS: 100 THA cases were performed with an anterior approach using intraoperative fluoroscopy (IF) to aid in cup positioning. Another group of 100 cases underwent THA with an anterior approach without the use of any fluoroscopy. Postoperative abduction and anteversion angles were measured using Martell's hip analysis software. RESULTS: Mean abduction angle was 43.2° (standard deviation (SD) = 4.5°) for the IF group versus 37.5°(SD = 7.4°) for cases without IF (p<0.001). 18% more cases with IF fell within the Lewinnek safe zone (p<0.001); however, a similar number of cases had over 50° of abduction. The mean anteversion angles of the two groups were also significantly different (IF 21.8° vs. 24.9°) (p<0.01). CONCLUSIONS: There was significantly less variation in cup position among the cases using IF with regards to abduction.

Patellar Cut and Composite Thickness: The Influence on Postoperative Motion and Complications in Total Knee Arthroplasty.

BACKGROUND: Little data exist on the influence of patellar thickness on postoperative motion or complications after total knee arthroplasty (TKA). This study addresses the following questions: Is postoperative motion influenced by change in composite patellar thickness? Is change in patellar thickness associated with more complications? And do more complications occur in the knees with a patellar bone remnant (<12 mm) and a native patellar thickness <18 mm? METHODS: In total, 3655 TKAs were performed by 3 surgeons over a 28-year interval. All knees had caliper measurement of patellar thickness before the patellar cut, after implantation of the component and postoperative motion recorded in the database 1 or 2 years after TKA. RESULTS: Patellar composite thickness was the same (1034 knees), thicker (1617 knees), and thinner (1004 knees). A significant but weak relationship was identified between the change in patellar thickness and motion (P < .01, ρ = -0.046); an increase in "composite patellar thickness" of 10 mm would result in a 3° loss of knee motion. Significant differences were identified between change in thickness and manipulations (P < .05), ruptures (P = .01), and patellar clunk/crepitus (P < .01). Examining knees with bone remnant thicknesses (<12 mm/≥12 mm), there was no difference in fractures (P = .26). No extensor ruptures occurred in knees with remnant thickness <12 mm. Comparing knees with native bone thickness (≤18 mm/>18 mm), significant differences were found in fractures (P < .01) and patellar radiolucencies (P = .01). CONCLUSION: As this data does not demonstrate a strong tendency toward losing motion when the patellar thickness is increased, the authors recommend avoiding compromise of the patellar bone stock and tendon insertion. When native patellar bone is thin (<18 mm), we recommend maintaining 12 mm of patellar bone stock and accept the increase in composite thickness.

Severely Obese Patients Have a Higher Risk of Infection After Direct Anterior Approach Total Hip Arthroplasty.

BACKGROUND: The orthopedic literature documents that obesity can place patients at increased risk for complications. This is the first study to document the increased risk of infection in obese patients after direct anterior approach (DAA) primary total hip arthroplasty (THA). METHODS: We retrospectively evaluated 1621 consecutive primary THAs performed with a DAA. Patients were stratified by body mass index <35 kg/m(2) (group 1) or ≥35 kg/m(2) (group 2). Rates of postoperative infection requiring revision, superficial wound dehiscence, return to the operating room, and total wound complications were compared. There were 1417 cases in group 1 and 204 in group 2. RESULTS: Five cases in each group had a deep infection, resulting in a significantly higher rate in group 2 (0.35% vs 2.5%, P = .0044, relative risk = 7.1). Superficial wound dehiscence was diagnosed in 13 (0.92%) THA in group 1 and 4 (1.96%) in group 2 (P = .256). The all-cause reoperation rate was 0.92% and 3.43% in each group, respectively (P = .008). The total rate of all studied complications was 1.27% compared to 4.41% (P = .0040, relative risk = 3.5). CONCLUSION: This is the first study to report on significantly increased rates of postoperative infection requiring revision in patients with body mass index ≥35 kg/m(2) after anterior approach hip arthroplasty. We believe it is the combination of immune dysfunction and proximity of the anterior incision to the inguinal crease and genitalia with overlying abdominal pannus that contributes to this risk. Further studies comparing other surgical approaches in obese patients are needed to determine if this complication is truly attributable to the DAA alone.

New Approach and Stem Increased Femoral Revision Rate in Total Hip Arthroplasty.

This study compared the femoral stem revision and loosening rates in primary total hip arthroplasty between 2 different approaches and stem designs. Recent reports comparing the direct anterior approach with either the posterior or lateral approach showed that patients undergoing the direct anterior approach have less pain and an accelerated functional recovery in the early postoperative period. After converting to an anterior approach, the authors observed an increased rate of femoral stem revision. From 2003 to 2009, a posterior or lateral approach was used to insert 514 stems of 2 designs. These cases included the use of an extensively coated cobalt-chrome stem (n=232) or a straight, dual-tapered, proximally porous-coated titanium stem (n=282). In the following years, from 2009 to 2012, 594 short, proximally coated, titanium tapered-wedge stems were inserted through a direct anterior approach. The revision rates of femoral stems inserted through a posterior approach or a lateral approach were compared with those inserted via a direct anterior approach. No stem revisions occurred in the posterior approach group or the lateral approach group, and 5 stems were revised in the anterior approach group for periprosthetic fracture or aseptic loosening (0.8%). Significantly more stem revisions occurred after the use of the new stem design and a direct anterior approach (P=.04).