Return to Cycling After Total Joint Arthroplasty.

BACKGROUND: As total joint arthroplasty (TJA) candidates become younger, patients' expectations continue to expand. We surveyed our patient population to determine rates of return to cycling after TJA so that we could provide more accurate counseling on performance and safety. METHODS: At our single institution, an online survey was generated and sent out to patients who had at least 3 months of follow-up. Patients were split into 4 categories based on surgery type: single total hip arthroplasty (THA), single total knee arthroplasty (TKA), multiple TJA, and revision TJA. RESULTS: A total of 1,029 surveys fit the inclusion criteria. The average age of the patient population was 69 years, with an average of 4.08 years from their time of most recent TJA surgery (maximum follow-up of 18.61 years). Nearly all those who were able to bike prior to surgery were able to return to cycling, with only 6% not being able to do so. There were 41.8% who returned to cycling less than 3 months after surgery. Most cyclists were able to return to their previous level. Patients who had a revision TJA had significantly lower rates of returning to cycling in comparison to single TKA, single THA, and multi-TJA (37.3%, 60.3%, 61.9%, and 60.3%, respectively, P < .005). Patients who never returned to cycling had higher revision rates in comparison to those who were able to get back on a bike (14.4 versus 9.2%, P = .01). CONCLUSIONS: A large proportion of patients who had prior cycling experience were able to return to bike riding within 3 to 6 months after TJA. Individuals who had revision TJA had lower rates of return to cycling in comparison to single TKA, single THA, and multi-TJA. Returning to cycling did not result in higher rates of revision.

Clinical outcomes of DAA and related techniques in hip arthroplasty.

Total hip arthroplasty (THA) has been one of the most successful surgical interventions in recent memory and is nicknamed by some the "Surgery of the Century". Over the past decade, there has been a drastic change in THA management with the rise of the direct anterior approach both globally and in the USA market. While many would remark that this has been driven by false marketing, it is clear that the direct anterior approach can be an effective and safe way to perform a THA.It is the goal of this review to highlight evidence of its outcomes and clinical advantages, in particular, how it can decrease dislocation, even in high-risk individuals, and result in faster recovery in the early postoperative period with decreased muscular inflammation. We will also highlight its major disadvantages, including but not limited to increased wound complications and risk for periprosthetic fracture. Hopefully, this review will provide up-to-date information on the current state of the direct anterior approach and provide recommendations on patients that would be optimal candidates for this technique.

Cruciate Substituting Implants in Primary Total Knee Arthroplasty.

The use of cruciate substituting (CS) total knee replacement has been increasing in popularity. There are numerous factors that have likely contributed to this expansion. The CS philosophy incorporates the ease of use commonly cited by advocates of the posterior stabilized (PS) total knee design with the bone preservation associated with a cruciate retaining (CR) design. The ultra-congruent highly cross-linked polyethylene liner increases stability without an appreciable change in wear. Furthermore, balancing the flexion and extension gaps does not require "titrating" the posterior cruciate ligament, improving the user-friendliness. This paper reviews the nuances of this implant design compared to PS and CR designs as well as provides surgical technique recommendations/considerations.

An elderly female with adult-onset Still's disease initially misdiagnosed as prosthetic joint infection after total knee arthroplasty: lessons in differential diagnosis and treatment.

BACKGROUND: High fever, knee swelling and pain after knee arthroplasty are often considered as symptoms of acute prosthetic joint infection. However, similar symptoms can also present as primary manifestations of adult-onset Still's disease, which creates some interference in differential diagnosis. To our knowledge, this is the first published case of misdiagnosis of adult Still's disease after total knee arthroplasty, who was initially misdiagnosed as an prosthetic joint infection due to the above-mentioned symptoms. The symptoms of the knee infection was not relieve after several revisions and continous antibiotic treatment. Finally, after several consultations and repeated evaluation it was diagnosed as adult-onset Still's disease. CASE PRESENTATION: A 77-year-old female who underwent bilateral total knee arthroplasty 6 years ago was admitted to our hospital with high fever, right knee effusion and painful knee. Based on the results of joint fluid aspiration and culture, we treated the right knee as acute hematogenous prosthetic joint infection. After three debridement and revision surgeries, the patient's symptoms continued to persist. Subsequent manifestations of other symptoms such as typical rash and sore throat and laboratory examination suggested the possibility of adult-onset Still's disease. So she underwent diagnostic steroid hormone therapy at the recommendation of a rheumatologist, and a final revision was performed after symptom was controlled. At the one-year follow-up, the patient's symptoms completely resolved and the knee revision was functioning well. CONCLUSIONS: When joint swelling and pain occurs after knee arthroplasty, the possibility of joint infection should not only be considered, but rheumatic autoimmune diseases should also be differentiated. Because the manifestations of joint infection and rheumatic immune disease sometimes overlap highly, when reasonable treatment over a period of time fails to relieve symptoms and signs, we should notice subtle differences in symptoms and laborotary tests and look for other diagnostic possibilities in time.

Reliability of Spinopelvic Measurements That May Influence the Cup Position in Total Hip Arthroplasty.

BACKGROUND: Spinopelvic pathology has been identified as a potential risk factor for instability after total hip arthroplasty. Spinopelvic radiographic parameters used to diagnose spinopelvic disease may also impact optimal cup placement. The purpose of this study was to assess the arthroplasty surgeon accuracy in making spinopelvic measurements. METHODS: Five fellowship-trained or in-training arthroplasty surgeons reviewed 44 lateral lumbar radiographs in two sessions. All evaluators were instructed how to perform measurements but had little experience in doing so. Traditional measurements included the pelvic tilt (PT), pelvic incidence (PI), and sacral slope (SS), and novel measurements included the acetabular ante-inclination (AI) and pelvic femoral angle. Surgeon measurements were compared with those made by experienced engineers. intraclass coefficients (ICCs) were calculated and interpreted. RESULTS: The interobserver reliability for 4 of 5 of the spinopelvic parameters was good to excellent (ICC >0.75) with the highest reliability seen for PI measurement (ICC = 0.939). Only moderate interobserver reliability was observed for AI measurement (ICC = 0.559). Intraobserver reliability was the highest for the PI and SS, ranging from moderate to good (ICC, 0.718 to 0.896). The lowest intraobserver reliability was seen for the AI (ICC range, 0.026 to 0.545) and pelvic femoral angle (ICC range, 0.035 to 0.828). Surgeon measurements of PT and SS were compared with engineer measurements with extremely poor correlation observed (ICC <0 for all). CONCLUSION: Surgeon intraobserver and interobserver reliability in making novel radiographic measurements was low compared with traditional radiographic measurements. Surgeon reliability in making traditional measurements of the PT and SS was very poor compared with experienced assessors using software-based measurements.

Cutibacterium colonization of the anterior and lateral thigh.

AIMS: Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint. METHODS: For this non-randomized non-blinded study, 101 adult patients scheduled for hip or knee surgery were recruited. For each, four 3 mm dermal punch biopsies were collected after administration of anaesthesia, but prior to antibiotics. Prebiopsy skin preparation consisted of a standardized preoperative 2% chlorhexidine skin cleansing protocol and an additional 70% isopropyl alcohol mechanical skin scrub immediately prior to biopsy collection. Two skin samples 10 cm apart were collected from a location approximating a standard direct anterior skin incision, and two samples 10 cm apart were collected from a lateral skin incision (suitable for posterior, direct-lateral, or anterolateral approaches). Samples were cultured for two weeks using a protocol optimized for Cutibacterium. RESULTS: A total of 23 out of 404 cultures (collected from 101 patients) were positive for a microorganism, with a total of 22 patients having a positive culture (22%). Overall, 15 of the cultures in 14 patients were positive for Cutibacterium sp. (65%), of which Cutibacterium acnes comprised the majority (n = 13; 87%). Other isolated microorganisms include coagulase-negative Staphylococcus (n = 6), Clostridium (n = 1), and Corynebacterium (n = 1). Of all positive cultures, 15 were obtained from the anterior location (65%), of which seven (60%) were from the most proximal biopsy location. However, these findings were not statistically significant (anterior vs lateral, p = 0.076; proximal vs distal, p =0.238). CONCLUSION: Approximately 14% (14/101) of the patients demonstrated a positive Cutibacterium colonization about the hip, the majority anteriorly. Given the high colonization rate of Cutibacterium, alternative skin preparations for total hip arthroplasty should be considered. Cite this article: Bone Joint J 2020;102-B(7 Supple B):52-56.

Does the use of intraoperative fluoroscopy improve postoperative radiographic component positioning and implant size in total hip arthroplasty utilizing a direct anterior approach?

BACKGROUND: The direct anterior approach (DAA) for total hip arthroplasty (THA) has gained recent popularity, with 1 purported benefit being access to intraoperative fluoroscopy. However, there are limited data demonstrating improved component position with the use of intraoperative fluoroscopy. The aim of this study is to compare radiographic implant positioning on 2 consecutive cohorts of patients undergoing DAA THA performed by 1 surgeon either utilizing intraoperative fluoroscopy or not. We hypothesized that there would be no relevant radiographic differences between the cohorts. METHODS: Forty-two consecutive patients underwent DAA THA utilizing fluoroscopy (IFC), and 42 consecutive patients then underwent DAA THA without fluoroscopy (NFC). Using preoperative pelvis radiographs and 6-week postoperative pelvis radiographs, acetabular anteversion, inclination, femoral offset, and templated component sizes vs final intraoperatively selected sizes were recorded and compared between cohorts. RESULTS: Acetabular inclination was 45.0° for IFC and 45.6° for NFC (P = .629). Femoral offset difference preoperatively and postoperatively was 0.8 mm for IFC and 1.3 mm for NFC (P = .734). Number of hips within the so-called safe zone was 32 for IFC and 33 for NFC (P = .794). These all demonstrated no significant difference between the cohorts. However, acetabular anteversion was 13.7° for IFC and 11.2° for NFC (P = .02). CONCLUSIONS: In this limited series, the routine use of intraoperative fluoroscopy did not improve implant positioning or sizing. This may be surgeon-specific or due to the result of the use of acetabular landmarks to guide placement of the components without fluoroscopy.

The James A. Rand Young Investigator's Award: Traditional Intravenous Fluid vs. Oral Fluid Administration in Primary Total Knee Arthroplasty: A Randomized Trial.

BACKGROUND: Optimal perioperative fluid management has not been established in patients undergoing orthopedic surgical procedures. Our purpose was to investigate the effects of perioperative fluid management (ie, preoperative, intraoperative, and postoperative) on patients undergoing total knee arthroplasty (TKA). METHODS: One hundred thirty patients who met inclusion criteria undergoing primary unilateral TKA were prospectively randomized into traditional (TFG) vs oral (OFG) perioperative fluid management groups. The primary outcome was change in body weight (BW). Secondary outcome measures included knee motion, leg girth, bioelectrical impendence, quadriceps activation, functional outcomes testing, Knee injury and Osteoarthritis Outcome Score JR, VR-12, laboratory values, vital signs, patient satisfaction, pain scores, and adverse events. RESULTS: The TFG had increased BW the evening of surgery (7.0 ± 4.3 vs 3.0 ± 3.9, P < .0001), postoperative day (POD) #1 (9.1 ± 4.3 vs 4.7 ± 3.9, P < .0001), and POD #2 (6.2 ± 5.0 vs 4.4 ± 4.0, P = .032). Bioelectrical impedance showed less limb edema in the OFG (4.2 ± 29.7 vs 17.8 ± 30.3, P < .0001) on POD #1. Urine specific gravity differences were seen preoperatively between groups (OFG, more hydrated, P = .002). Systolic blood pressure decrease from the baseline was greater in the OFG on arrival to the floor (19.4 ± 13.5 vs 10.6 ± 12.8, P < .0001) and 8 (23.4 ± 13.3 vs 17.0 ± 12.9, P = .006) and 16 (25.8 ± 13.8 vs 25.8 ± 13.8, P = .046) hours after floor arrival. The TFG had more urine output on POD #1 (3369 mL ± 1343 mL vs 2435 mL ± 1151 mL, P < .0001). The OFG were more likely to go home on POD #1 than the TFG (63 vs 56, P = .02). CONCLUSION: Oral fluid intake with IVF restriction in the perioperative period after TKA may offer short-term benefits with swelling and BW fluctuations. The authors continue to limit perioperative IVFs and encourage patient initiated fluid intake.

Revisions of Modular Metal-on-metal THA Have a High Risk of Early Complications.

BACKGROUND: The risk of early complications is high after monoblock acetabular metal-on-metal (MoM) THA revisions. However, there is a paucity of evidence regarding clinical complications after isolated head-liner exchange of modular MoM THA. QUESTIONS/PURPOSES: The purposes of this study were (1) to describe the frequency of early complications after an isolated head-liner exchange revision of modular MoM THA; and (2) to determine whether patients who experienced complications or dislocation after head-liner exchanges had higher serum chromium (Cr) or cobalt (Co) ion levels than those who did not. METHODS: A review of our institution's total joint registry retrospectively identified 53 patients who underwent 54 liner exchange revisions of a modular acetabular MoM THA. The study period was from April 2008 to April 2016 at a single tertiary care center. During this period, isolated head-liner exchanges (rather than more extensive revisions) were performed in patients if they did not have evidence of loosening of the acetabular or femoral components. Reasons for revision surgery included pain, mechanical symptoms, radiographic evidence of osteolysis, elevated serum metal ions, and MRI abnormalities with 40 of the 54 hips having pain or mechanical symptoms and 38 of 54 hips having multiple reasons for revision before surgery. Patients were excluded if they did not meet the minimum postrevision followup or had the modular liner exchange secondary to infection. All revisions were from a single manufacturer with one head-liner exchange of a MoM THA from another manufacturer excluded during the study period. The mean time from index MoM THA to modular exchange was 96 (SD ± 36) months. Because the focus of this study was early complications, we had a minimum 90-day followup duration for inclusion. Mean followup after revision was 15 months (SD ± 12); a total of 56% (30 of 54) had followup of at least 12 months' duration. Complications (dislocation, infection) and reoperations were obtained by chart review performed by individuals other than the treating physician(s). Serum metal ion levels were obtained before head-liner exchange. The median serum Cr and Co levels were 6 µg/L (range, 0-76 µg/L) and 12 µg/L (range, 0-163 µg/L), respectively. RESULTS: Of the 54 revision THAs, 15 (28%) developed complications. Nine (17%) occurred within 90 days of the revision surgery and 11 (20%) resulted in reoperation. The most common complication was dislocation (12 of 54 [22%]) with recurrent dislocation noted in eight of these 12 patients. All patients with recurrent dislocation continued to dislocate and underwent repeat revision. Patients with dislocation had higher median serum Cr and Co ion levels than those without dislocation (Cr: 24 [range, 11-76] versus 4 [range, 0-70], p = 0.001 [95% confidence interval {CI}, 10-57]; Co: 41 [range, 6-163] versus 8 [range, 0-133], p = 0.016 [95% CI, 6-141]). Three (6%) of the 54 patients underwent repeat surgery for deep space infection. CONCLUSIONS: Complications and reoperations are common after modular head-liner exchange in the setting of a failed MoM THA. Our study likely underestimates the frequency of complications and revisions because the followup period in this report was relatively short. Dislocation is the most common complication and elevated serum metal ion levels may be a predictor of dislocation. These findings are concerning and surgeons should be aware of the high complication risk associated with this procedure. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Direct Anterior Hip Replacement Does Not Pose Undue Radiation Exposure Risk to the Patient or Surgeon.

BACKGROUND: The fluoroscopically assisted direct anterior approach for total hip arthroplasty has gained interest in recent years. One of the perceived advantages is the use of fluoroscopy to aid in the positioning of implants. The purpose of this study was to measure the radiation entrance surface dose to anatomically important areas of both patients and surgeons during direct anterior approach total hip arthroplasty. METHODS: Radiation dosimetry badges were placed at the sternal notch and pubic symphysis of 50 patients undergoing direct anterior approach total hip arthroplasty. Badges were also placed on the surgeons outside of their lead aprons at the level of the thyroid. Three fellowship-trained arthroplasty surgeons were involved in the study. Radiation exposure of each badge was measured after each case (surgeon and patient). The cumulative dose was also calculated for the surgeons. To limit surgeon bias during the study, 50 consecutive direct anterior approach total hip arthroplasties that occurred prior to this study were analyzed for total fluoroscopic dose and time and served as a control group. RESULTS: Forty-five subjects met study criteria. In the study group, 1 patient had a detectable thyroid exposure equal to 1 mrem. Seven patients had a detectable radiation entrance surface dose at the pubic symphysis (range, 1 to 7 mrem). No radiation entrance surface dose was detectable in the remaining 44 patients at the sternal notch and 38 patients at the pubic symphysis. Surgeons in the study did not experience a detectable radiation entrance surface dose. The mean fluoroscopic time was 13.72 seconds (range, 6.7 to 28.7 seconds). The mean patient radiation exposure was 178 mrem (range, 54 to 526 mrem). CONCLUSIONS: This study demonstrates that during direct anterior approach total hip arthroplasty, the mean patient entrance surface dose at the pubic symphysis and the sternal notch is not detectable in most patients. The mean patient exposure in this study during direct anterior approach total hip arthroplasty was 178 mrem, which is less than a single pelvic radiograph (600 mrem). No surgeon in our study demonstrated a detectable radiation entrance surface dose. Our data suggest that direct anterior approach total hip arthroplasty typically results in a negligible or very low dose of absorbed radiation exposure to the patient and the surgeon. CLINICAL RELEVANCE: We believe this study to have clinical relevance because both patients and surgeons have evidence that utilization of fluoroscopy during direct anterior total hip replacement places both parties at a relatively low radiation exposure risk.

Porous-Coated Metaphyseal Sleeves for Severe Femoral and Tibial Bone Loss in Revision TKA.

BACKGROUND: Metaphyseal bone loss is commonly encountered in revision total knee arthroplasty (TKA). Anderson Orthopaedic Research Institute types 2 and 3 defects generally require some form of metaphyseal fixation or augmentation. This study evaluates the midterm results of stepped, porous-coated metaphyseal sleeves in revision TKA in the setting of severe bone loss. METHODS: Patients who underwent revision TKA using metaphyseal sleeves from March 2006 to May 2014 at our institution were identified from a prospective research database. Preoperative patient characteristics and operative data were reviewed. Postoperative outcomes were compared with preoperative values. Primary study outcomes included complications, reoperations, radiographic assessment of sleeve osteointegration, and survivorship. RESULTS: One hundred sixteen knees (108 patients) underwent revision TKA with 152 metaphyseal sleeves (111 tibial and 41 femoral). Anderson Orthopaedic Research Institute defect classification included 5 type 2A, 89 type 2B, and 17 type 3 tibial defects; and 3 type 2A, 34 type 2B, and 4 type 3 femoral defects. There were 3 intraoperative fractures (1.9%) associated with sleeve preparation and/or insertion. Six knees (5 patients) were lost to follow-up and 5 patients (6 knees) died before 2 years. Of the remaining 104 knees (98 patients, 134 sleeves), mean follow-up was 5.3 years (range 2-9.6 years). Nineteen knees (16.4%) required reoperation, most commonly for recurrent infection. Only one sleeve demonstrated radiographic evidence of failed osteointegration, but did not require revision. Two sleeves (1.5%) required removal and/or resection for recurrent infection. CONCLUSION: This large retrospective series illustrates the utility of porous metaphyseal sleeves in revision TKA with a low rate of intraoperative complications, excellent osteointegration, and long-term fixation.

Metal Artifact Reduction Sequence MRI Abnormalities in Asymptomatic Patients with a Ceramic-on-Polyethylene Total Hip Replacement.

BACKGROUND: Magnetic resonance imaging (MRI) is a commonly utilized screening modality in patients with a metal-on-metal (MoM) total hip replacement. The prevalence of clinically important fluid collections may be overestimated since these collections have been reported to occur in asymptomatic patients with MoM and other bearing surfaces. The purpose of this study was to determine the frequency and types of MRI-documented adverse local tissue reactions in asymptomatic patients with a ceramic-on-polyethylene (CoP) total hip replacement. METHODS: Forty-four patients (50 hips) with a minimum 2-year follow-up after total hip arthroplasty with CoP implants and a Harris hip score of >90 were enrolled in this study. The inclusion criteria were the absence of hip pain and the availability of appropriate follow-up radiographs. All patients underwent a metal artifact reduction sequence (MARS) MRI scan to determine the presence of fluid collections in asymptomatic patients with a CoP bearing surface. RESULTS: Fluid collections were observed in 9 (18%) of 50 asymptomatic hips in this cohort. There were 5 hips with intracapsular synovitis, and 2 of these hips had a thickened synovium. Extra-articular fluid collections with direct intracapsular communication were identified in 4 additional hips. Two of these hips had a thickened synovium. No signs of osteolysis or evidence of adverse local tissue reactions were noted on radiographs at the most recent follow-up. CONCLUSIONS: This study revealed that fluid collections are not uncommon after total hip arthroplasty with CoP implants. Synovial thickening may be present and is more prevalent than has been reported in previous studies involving metal-on-polyethylene (MoP) bearing surfaces. The clinical importance and natural history of these findings remain unknown. LEVEL OF EVIDENCE: Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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

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

False-positive Cultures After Native Knee Aspiration: True or False.

BACKGROUND: Synovial fluid aspiration is a routine practice used by most orthopaedic surgeons to aid in the diagnosis of joint infection. In patients for whom there is a low pretest probability of infection, a positive culture-particularly if it is a broth-only culture-may be considered a contaminant, especially if the bacterial species are skin pathogens. To our knowledge no study has evaluated the incidence of contamination of aspirations from the native knee. QUESTIONS/PURPOSES: What is the frequency of false-positive cultures among knee aspirations of the native knee? METHODS: Two hundred patients, with a total of 200 knees, with the diagnosis of degenerative osteoarthritis undergoing a total knee arthroplasty (TKA) were identified for this study. None of these patients had symptoms, signs, or laboratory studies to suggest the presence of joint infection; a positive culture in this population therefore would be considered contaminated. Thirty-two (16%) patients were excluded secondary to a dry aspiration. One patient was enrolled in the study but did not have the knee aspirated and another patient's specimen was accidentally discarded. Each knee was aspirated under sterile conditions before performing the TKA. The fluid was sent for cell count and culture. If insufficient fluid was obtained for both cell count and culture, culture was performed rather than cell count. RESULTS: There were no false-positive cultures (zero of 166 [0%]) in aspirations of native knees. CONCLUSIONS: Our study would indicate that when done properly under sterile technique, cultures taken from knee arthrocentesis in patients without prosthetic joints should not be affected by perceived contaminant species. A positive specimen finding on culture should raise a strong suspicion of bacterial septic arthritis. Future studies should include more specimens as well as knees with prior TKA to help further identify the rate of false-positive cultures in knee arthrocentesis in both populations. LEVEL OF EVIDENCE: Level I, diagnostic study.

Patellar component design influences size selection and coverage.

BACKGROUND: Patellofemoral (PF) complications following total knee arthroplasty continue to occur. Outcomes are influenced by implant design, size and alignment in addition to patient factors. The objective of this study was to assess the effect of implant design, specifically round versus oval dome patellar components, on size selected and bony coverage in a population of 100 patients. METHODS: Intraoperative assessments of patella component size were performed using surgical guides for round and oval designs. Digital images of the resected patellae with and without guides were calibrated and analyzed to measure bony coverage. Lastly, the medial-lateral location of the median ridge was assessed in the native patella and compared to the positioning of the apex of the patellar implants. RESULTS: In 82% of subjects, a larger oval implant was selected compared to a round. Modest, but statistically significant, differences were observed in selected component coverage of the resected patella: 82.7% for oval versus 80.9% for round. Further, positioning of the apex of oval patellar components reproduced the median ridge of the native patella more consistently than for round components. CONCLUSIONS: These findings characterized how implant design influenced size selection and coverage in a population of patients. The ability to "upsize" with oval dome components led to increases in bony coverage and better replication of the median ridge compared to round components. Quantifying the interactions between implant design, sizing and coverage for a current implant system in a population of patients supports surgical decision-making and informs the design of future implants.

Determining False Positive Rates of Leukocyte Esterase Reagent Strip When Used as a Detection Tool for Joint Infection.

BACKGROUND: Use of leukocyte esterase (LE) testing of synovial fluid as an adjunct to the infection workup in total joint arthroplasty patients has been advocated. The purpose of this study was to determine the false positive rate of this test. METHODS: Two hundred patients with the diagnosis of degenerative osteoarthritis undergoing a total knee arthroplasty were identified for this study. The knee joint was aspirated under sterile conditions before performing the total knee arthroplasty. The fluid was analyzed with an LE reagent strip. RESULTS: There were 27 bloody and 17 dry aspirations. One hundred forty-nine patients produced an aspiration that allowed for LE testing. There was 1 positive LE result. The specificity of the LE test was found to be 99.3%. CONCLUSION: These data suggest the LE strip as a part of the workup for infection in a native knee should yield few false positive results.

Corrosion of the Head-neck Junction After Total Hip Arthroplasty.

Corrosion of the head-neck junction of implants used in total hip arthroplasty is a complex problem. Clinical severity appears to be multifactorial, and the predictive variables have yet to be consistently identified in the literature. Corrosion should be considered in the differential diagnosis of hip pain following total hip arthroplasty regardless of the type of bearing surface used. The most common presentation, pain followed by instability, is similar to complications associated with metal-on-metal articulations. The diagnosis of implant corrosion of the head-neck junction can be challenging; an infection workup should be performed along with analysis of serum metal ion levels and cross-sectional imaging. In the short term, a well-fixed stem may be retained, and the exchange of an isolated head with a ceramic femoral head seems to be a promising option for certain implants. Further research with longer follow-up is warranted, and high levels of evidence are needed to determine whether this approach is generalizable.

Does Tourniquet Use in TKA Affect Recovery of Lower Extremity Strength and Function? A Randomized Trial.

BACKGROUND: Tourniquet use during total knee arthroplasty (TKA) improves visibility and reduces intraoperative blood loss. However, tourniquet use may also have a negative impact on early recovery of muscle strength and lower extremity function after TKA. QUESTIONS/PURPOSES: The purpose of this study was (1) to determine whether tourniquet use affects recovery of quadriceps strength (primary outcome) during the first 3 postoperative months; and (2) to examine the effects of tourniquet application on secondary outcomes: voluntary quadriceps activation, hamstring strength, unilateral limb balance as well as the effect on operative time and blood loss. METHODS: Twenty-eight patients (mean age 62 ± 6 years; 16 men) undergoing same-day bilateral TKA (56 lower extremities) were enrolled in a prospective, randomized study. Subjects were randomized to receive a tourniquet-assisted knee arthroplasty on one lower extremity while the contralateral limb underwent knee arthroplasty without extended tourniquet use. In the former group, the tourniquet was inflated just before the incision was made and released after cementation; in the latter group, a tourniquet was not used (10 of 28 [36%]) or inflated only during component cementation (18 of 28 [64%]). The choice of no tourniquet or use just during cementation was based on surgeon choice, because some surgeons felt a tourniquet during cementation was necessary to achieve a dry surgical field to maximize cement fixation. A median parapatellar approach and the identical posterior-stabilized TKA design were used by all four fellowship-trained knee surgeons involved. Isometric quadriceps strength, hamstring strength, voluntary quadriceps activation, and unilateral balance were assessed preoperatively, 3 weeks, and 3 months after bilateral knee arthroplasty. Other factors, including pain, range of motion, and lower extremity girth, were assessed for descriptive purposes at each of these time points as well as on the second postoperative day. RESULTS: Quadriceps strength was slightly lower in the tourniquet group compared with the no-tourniquet group (group difference = 11.27 Nm [95% confidence interval {CI}, 2.33-20.20]; p = 0.01), and these differences persisted at 3 months after surgery (group difference = 9.48 Nm [95% CI, 0.43-18.54]; p = 0.03). Hamstring strength did not differ between groups at any time point nor did measures of quadriceps voluntary activation or measures of unilateral balance ability. There was less estimated intraoperative blood loss in the tourniquet group (84 ± 26 mL) than in the no-tourniquet group (156 ± 63 mL) (group difference = -74 mL [95% CI, -100 to -49]; p < 0.001). However, there was no difference in total blood loss between the groups (group difference = -136 mL [95% CI, -318 to 45]; p = 0.13). CONCLUSIONS: Patients who underwent TKA using a tourniquet had diminished quadriceps strength during the first 3 months after TKA, the clinical significance of which is unclear. Future studies may be warranted to examine the effects of tourniquet use on long-term strength and functional outcomes. LEVEL OF EVIDENCE: Level I, therapeutic study.

The squeaking hip: a cause for concern-disagrees.

Total hip arthroplasty with ceramic-on-ceramic bearing surfaces has demonstrated low wear with excellent clinical outcomes. More recently, concerns have surfaced because of the presence of audible squeaking in some ceramic-on-ceramic THA patients. The incidence of this phenomenon has been low and has infrequently required reoperation. The exact etiology of squeaking remains unclear but is likely related to variations in surgical technique, patient selection, and implant design, particularly those designs that result in premature femoral neck-acetabular component rim impingement such as the presence of modular ceramic liner designs that are placed within a titanium encasement which has an extended rim. Hopefully, with continued improvements in design, materials, and component positioning, squeaking following ceramic-on-ceramic THA can be minimized.