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.

A back table ultraviolet light decreases environmental contamination during operative cases.

BACKGROUND: The purpose of this study is to assess the impact of a germicidal ultraviolet light-emitting diode (LED) on the contamination level of a back table in the operating room (OR) during total joint arthroplasty procedures. METHODS: Eight Tryptic Soy Agar petri plates were placed on a table located near the operative field and exposed to air. One plate was removed on the hour over an 8-hour time span. The back table had either an UV-LED for disinfection or a sham UV-LED. This process was repeated in 12 different ORs (6 with UV light, 6 with sham device). The plates were then incubated for 48 hours at 36°C ± 1°C . Colony forming units (CFU) were recorded 24 and 48 hours after incubation. RESULTS: There was a statistically significant difference in total CFUs between the intervention vs sham at 24-hours (27 vs 95, P = .0001) and 48-hours (38 vs 122, P < .0001). The multivariate analysis revealed that the 24-hour and 48-hour count, the predictors UV light (P = .002) and hour of plate removal (P = .050) were statistically significantly associated with CFU counts. Together, the predictor variables explained 15.8% and 23.0% of the variance in CFU counts at 24- and 48-hours, respectively. CONCLUSIONS: A back table UV-LED may decrease environmental contamination near the operative field. This has potential to lead to a decrease in joint infection.

Incidence and Predictive Risk Factors of Postoperative Urinary Retention After Primary Total Knee Arthroplasty.

BACKGROUND: Postoperative urinary retention (POUR) after total knee arthroplasty (TKA) may cause urologic injury and delay patient discharge. This study measures the incidence of POUR and identifies predictive risk factors. METHODS: Two-hundred seventy-one consecutive patients undergoing primary unilateral TKA were prospectively enrolled. Bladder scans were performed in the postanesthesia care unit (PACU) and every four hours thereafter. POUR was defined as >400cc with inability to void and was treated with catheterization. Patient demographics, urologic history, operative data, perioperative medications, and bladder scanner volumes were investigated with the univariate and multivariate logistic regression analysis. RESULTS: Fifty-five patients (20%) developed POUR. Compared with non-POUR patients, PACU bladder scan volumes were greater in patients who developed POUR (344cc vs 120cc, P < .001). POUR patients had lower BMI (27.8 vs 29.4, P = .03), longer operative duration (83.9 vs 76.0 minutes, P = .002), and lower ASA scores (2.2 vs 2.4, P = .02). Total intravenous fluid was equivalent between groups (1134cc vs 1185cc, P = .41). POUR patients received less narcotics measured by morphine milligram equivalents (16.1 vs 23.9, P < .001). Fifteen variables including spinal type (bupivacaine and ropivacaine) and paralytic use were not predictive of POUR. Potentially predictive variables included anesthetic types administered (spinal, general, regional, and combination) and perioperative administration of nonsteroidal anti-inflammatory drugs (NSAIDs), glycopyrrolate, and muscle relaxants. The multivariate analysis showed that NSAIDs (P = .05) and glycopyrrolate (P = .04) were significant predictors. CONCLUSION: A significant percentage of patients develop POUR after TKA. Select patient demographics and PACU bladder scanning may identify those at risk. Appropriate pain control and judicious use of perioperative NSAIDs and glycopyrrolate may help minimize the risk of POUR.

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.

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.

Midterm Prospective Comparative Analysis of 2 Hard-on-Hard Bearing Total Hip Arthroplasty Designs.

INTRODUCTION: Hard-on-hard (HoH) bearing surfaces in total hip arthroplasty (THA) are commonly utilized in younger patients and may decrease mechanical wear compared to polyethylene bearing surfaces. To our knowledge, no study has prospectively compared the 2 most common HoH bearings, ceramic-on-ceramic (CoC) and metal-on-metal (MoM) THA. MATERIALS AND METHODS: We prospectively enrolled 40 patients to undergo an MoM THA and 42 patients to undergo a CoC THA utilizing the same acetabular component. Patients were followed up for a minimum of 2 years. Comparative outcomes included clinical scores, revision or reoperation for any reason, complication rates, and radiographic outcomes. RESULTS: The average follow-up was significantly longer in the CoC cohort (94 vs 74 months; P = .005). The CoC cohort had significantly improved Harris Hip Scores (95 vs 84; P = .0009) and pain scores (42 vs 34; P = .0003). The revision (0% vs 31%; P = .0001), reoperation (7.5% vs 36%; P = .004), and complication rates (10% vs 56%; P = .0001) were significantly lower in the CoC cohort. There were no statistically significant differences in radiographic parameters. CONCLUSION: The clinical outcomes in the CoC cohort exceeded the MoM cohort. It is unlikely that another prospective comparative study of HoH THAs will be conducted. Our midterm results support the use of CoC THA as a viable option that may reduce long-term wear in younger patients. Close surveillance of MoM THA patients is recommended considering the higher failure and complication rates reported in this cohort.

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.

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.

Use of a computerized arthroplasty registry to generate operative reports decreases transcription errors.

OBJECTIVES: Despite the clear importance of the operative report in the electronic medical record, few studies have addressed the quality. METHODS: We prospectively evaluated 300 consecutive patients undergoing primary total joint arthroplasties for operative report errors utilizing three different forms of documentation (standard dictation vs. templated dictation vs. a computer registry database generated operative report). The three types of reports were evaluated for errors which were classified as either major or minor. RESULTS: There were significantly more total errors in the standard dictation group compared to both the computer registry database generated (p<0.001) and the templated operative reports (p<0.001). Major errors were significantly reduced in the database generated reports compared to the templated (p<0.001) and standard dictation groups (p<0.001). There were significantly more minor errors in the standard dictation group (p<0.001) compared to the other two groups. No statistically significant differences in major errors were noted when comparing standard vs. templated operative reports. There was no difference in minor or total errors between the database generated and templated operative reports. CONCLUSIONS: The use of a computer registry database generated operative report resulted in fewer major errors versus a templated or standard dictated operative report. Further research is warranted in this area to validate these findings across subspecialties and institutions.

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.

What Preoperative Radiographic Parameters Are Associated With Increased Medial Release in Total Knee Arthroplasty?

BACKGROUND: Preoperative varus deformity of the knee is a common malalignment in patients undergoing primary total knee arthroplasty (TKA). We are unaware of any studies that have correlated how various preoperative radiographic parameters can predict the amount of medial releases performed to achieve optimal coronal alignment and ligamentous balance. METHODS: A retrospective review was performed on 67 patients who required at least a medial tibial reduction osteotomy (MTRO) during primary TKA to achieve coronal balance. This patient population was matched 1:1 to another cohort of TKA patients by age, gender, and body mass index who did not require an MTRO. A radiographic evaluation was used to compare the 2 cohorts. RESULTS: Preoperatively, the MTRO cohort was noted to have significantly increased varus tibiofemoral (86.12° vs 93.43°), tibial articular surface (85.79° vs 87.54°), and medial tibial articular surface angles (75.22° vs 85.34°) compared to the control cohort. The MTRO cohort had 3.13 mm of medial tibial offset and 9.06 mm of lateral joint space opening and the control cohort had 0.09 mm and 4.07 mm, respectively. The medial tibial articular surface angle and lateral joint space widening were statistically associated with the MTRO cohort. The final tibiofemoral angle in the MTRO cohort was 92.43° and was 93.40° in the control cohort. CONCLUSION: The MTRO cohort was noted to have several preoperative radiographic parameters that were significantly different than the control cohort. However, the medial tibial articular surface angle and lateral joint space widening were the only radiographic parameters that were statistically associated with requiring an MTRO.

Tibial Tray Thickness Significantly Increases Medial Tibial Bone Resorption in Cobalt-Chromium Total Knee Arthroplasty Implants.

BACKGROUND: Stress shielding is an uncommon complication associated with primary total knee arthroplasty. Patients are frequently identified radiographically with minimal clinical symptoms. Very few studies have evaluated risk factors for postoperative medial tibial bone loss. We hypothesized that thicker cobalt-chromium tibial trays are associated with increased bone loss. METHODS: We performed a retrospective review of 100 posterior stabilized, fixed-bearing total knee arthroplasty where 50 patients had a 4-mm-thick tibial tray (thick tray cohort) and 50 patients had a 2.7-mm-thick tibial tray (thin tray cohort). A clinical evaluation and a radiographic assessment of medial tibial bone loss were performed on both cohorts at a minimum of 2 years postoperatively. RESULTS: Mean medial tibial bone loss was significantly higher in the thick tray cohort (1.07 vs 0.16 mm; P = .0001). In addition, there were significantly more patients with medial tibial bone loss in the thick tray group compared with the thin tray group (44% vs 10%, P = .0002). Despite these differences, there were no statistically significant differences in range of motion, knee society score, complications, or revision surgeries performed. CONCLUSION: A thicker cobalt-chromium tray was associated with significantly more medial tibial bone loss. Despite these radiographic findings, we found no discernable differences in clinical outcomes in our patient cohort. Further study and longer follow-up are needed to understand the effects and clinical significance of medial tibial bone loss.

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.

Primary total knee arthroplasty in a patient with a chronic extensor mechanism deficiency.

A 44-year-old female presented with a chief complaint of left knee pain and dysfunction. The patient had a complex surgical history including patellar fracture repair, subsequent patellar ligament repair, and ultimately allograft reconstruction which was complicated by septic arthritis requiring graft resection. On presentation to our clinic, she was noted to have significant degenerative disease in addition to chronic extensor mechanism deficiency. She underwent primary total knee arthroplasty with concomitant tibial tubercle osteotomy and advancement. The patient has had an excellent result postoperatively including return of full range of motion without residual extensor lag.

In vivo comparison of hip mechanics for minimally invasive versus traditional total hip arthroplasty.

BACKGROUND: Minimally invasive surgery has been developed to reduce incision length, muscle damage, and rehabilitation time. However, reduced exposure of anatomical landmarks may result in technical errors and inferior implant survivorship. The objective of this study was to compare in vivo motions and hip joint contact forces during gait in total hip arthroplasty subjects, performed with either minimally invasive surgery or standard surgical approaches. METHODS: Fifteen subjects implanted using either minimally invasive surgery anterolateral, minimally invasive surgery posterolateral, or traditional posterolateral total hip arthroplasty were evaluated using fluoroscopy while performing gait on a treadmill. Kinematics, obtained using 3D-to-2D image registration technique, were input as temporal functions in a 3D inverse dynamic mathematical model that determines in vivo soft tissue and hip contact forces. FINDINGS: The subjects implanted with posterolateral and anterolateral minimally invasive surgery demonstrated significantly less separation than those implanted with the traditional approach (P<0.01). The minimally invasive surgery subjects also experienced lower average maximum peak forces, with 3.2 body weight for the anterolateral minimally invasive surgery and 2.9 body weight for the posterolateral minimally invasive surgery subjects, compared to 3.5 body weight for the traditional subjects (P=0.02 and P=0.03, respectively). INTERPRETATION: This is the first study to compare in vivo weight-bearing kinematics, separation and kinetics for traditional, anterolateral minimally invasive surgery and posterolateral minimally invasive surgery total hip arthroplasty subject groups. Our data indicated in all analyzed parameters differences between the minimally invasive surgery and the traditional groups, with favorable results for the minimally invasive surgery subjects. This may be related, to a reduction in stabilizing soft tissues after a minimally invasive surgery procedure, leading to lower bearing surface forces at the femoral head--acetabular cup interface.