Registration of Bony Landmarks and Soft Tissue Laxity during Robotic Total Knee Arthroplasty is Highly Reproducible.

INTRODUCTION: There is growing interest and enthusiasm for robotic total knee arthroplasty (TKA). Many robotic systems require registration of bony landmarks as well as a dynamic soft tissue evaluation to plan femoral and tibial resections. Variability in this user-driven registration can introduce error and undermine the purported precision and accuracy offered by robotics. The purpose of this study was to evaluate inter- and intrarater reliability in robotic registration with a new robotic system (ROSA®; Zimmer-Biomet, Warsaw, IN). METHODS: Two unpaired cadaveric knee specimens were exposed, and optical arrays were placed into the femur and tibia. Three separate evaluators conducted repeated trials of anatomic registration and assessment of soft tissue laxity, as well as coronal alignment, sagittal alignment, femoral size, and maximum opening in the medial and lateral compartments in both flexion and extension. Repeated trials were conducted using these specimens with and without preoperative imaging for landmarking (image-based and image-free workflows). An Intraclass Correlation Coefficient (ICC) was calculated for each observer and across observers to determine intra-and interrater reliability, respectively, in robotic registration. RESULTS: There was good to excellent reliability for all conditions, and all correlation coefficients were >0.767. On average, ICCs for intrarater reliability were excellent for Doctor 1 (0.952), Doctor 2 (0.975), and Doctor 3 (0.925). On average, the ICCs for interrater reliability were excellent for both the "Registration + Gap Assessment" condition (0.961) and the "Gap Assessment" condition (0.994). CONCLUSION: Our results show a high repeatability of registration of anatomic landmarks and gap assessment among observers using this robotic system for both image-based and image-free software.

Risks and Complications After Arthroplasty for Pathological or Impending Pathological Fracture of the Hip.

BACKGROUND: Treatment options for metastatic osseous lesions of the proximal femur include hemiarthroplasty (HA) or total hip arthroplasty (THA) depending on lesion characteristics and patient demographics. Studies assessing short-term outcomes after HA/THA in this patient population are limited. Therefore, the purpose of this present study was to identify short-term rates of morbidity and mortality after HA/THA for pathological proximal femur fractures, as well as readmission and reoperation rates and reasons. METHODS: This study utilized a large, prospectively collected registry to identify patients who underwent HA/THA between 2011 and 2018. Patients were stratified by indication for surgery, including pathological fracture, nonpathological fracture, and osteoarthritis. Baseline patient characteristics and postoperative complications were compared using bivariate and/or multivariate analysis. RESULTS: In total, 883 patients undergoing HA/THA for a pathological fracture were identified. Relative to an osteoarthritis cohort, these patients tended to be older, had a lower body mass index, and had significantly more preoperative comorbidities. These patients had high rates of total complications (13.93%), including thirty-day mortality (3.29%), unplanned return to the operating room (4.98%), and pulmonary complications (3.85%). Patients with pathological fracture had a longer operative duration relative to osteoarthritis and nonpathological cohorts (+27 and +25 minutes, respectively), despite having high rates of HAs performed. CONCLUSION: Patients undergoing hip arthroplasty for pathologic proximal femur fracture have increased morbidity and mortality relative to an osteoarthritis cohort. However, patients with a pathological fracture have similar rates of morbidity and mortality when compared with a nonpathological fracture cohort, but did experience higher rates of perioperative blood transfusion and unplanned readmissions. LEVEL OF EVIDENCE: III.

One Versus Two Doses of Intravenous Tranexamic Acid in Total Knee Arthroplasty.

Tranexamic acid (TXA) has been shown to reduce blood loss and postoperative transfusions in total knee arthroplasty (TKA). There is no consensus on the ideal dosing regimen in the literature, although there is a growing body of literature stating there is little benefit to additional doses. Our study compared one versus two doses of TXA in primary TKA and its effect on postoperative transfusion rate. We retrospectively reviewed patients undergoing primary TKA at our two high-volume arthroplasty centers between 2013 and 2016. Patients were included if they underwent unilateral primary TKA, and received one or two doses of intravenous TXA. Patients receiving therapeutic anticoagulation were excluded. Our primary outcome was postoperative transfusion rate. Secondary outcomes included blood loss, length of stay, rate of deep vein thrombosis or pulmonary embolism (DVT/PE), readmission and reoperation.A total of 1,191 patients were included: 891 received one dose and 300 received two doses. There was no significant difference in rate of transfusion, deep vein thrombosis or pulmonary embolism (DVT/PE), blood volume loss, and reoperation. There was a significantly higher risk of readmission (6.7 vs. 2.4%, odds ratio [OR] 2.96, p < 0.001) and reoperation (2.0 vs. 0.6%, OR 3.61, p = 0.024) in patients receiving two doses. These findings were similar with subgroup analysis of patients receiving only aspirin prophylaxis.In unilateral TKA, there is no difference in transfusion rate with one or two doses of perioperative TXA. There was no increased risk of thromboembolic events between groups, although the two-dose group had a higher rate of readmission and reoperation. Given the added cost without clear benefit, these findings may support administration of one rather than two doses of TXA during primary TKA.

Preoperative Albumin, Transferrin, and Total Lymphocyte Count as Risk Markers for Postoperative Complications After Total Joint Arthroplasty: A Systematic Review.

INTRODUCTION: The purpose of this systematic review is to identify whether poor nutrition, as defined by the more commonly used markers of low albumin, low transferrin, or low total lymphocyte count (TLC), leads to more postoperative complications. We hypothesized that it may be possible to identify the levels of these laboratory values at which point total joint arthroplasty (TJA) may be ill advised. To this end, we analyzed the available literature regarding links between these three variables on postoperative complications after TJA. METHODS: This systematic review was done in two parts: (1) In the first part, we reviewed the most commonly used malnutrition marker, albumin. (2) In the second part, we reviewed TLC and transferrin. We accessed PubMed, EMBASE, and Cochrane Library using relevant keywords to this study. The biostatistics were visualized using a random-effects forest plot. We compared data from all articles with sufficient data on patients with complications (ie, cases) and patients without complications (ie, noncases) among the two groups, malnourished and normal nutrition, from albumin, transferrin, and TLC data. RESULTS: A meta-analysis of seven large-scale articles detailing the complications of albumin led to an all-cause relative risk increase of 1.93 when operating with hypoalbuminemia. This means that in the studies detailed enough to incorporate in this pooled analysis, operating on elective TJAs with low albumin is associated with a 93% increase in all measured complications. In the largest studies, analysis of transferrin levels for the most common complications revealed a relative risk increase of 2.52 when operating on patients with low transferrin levels. There were not enough subjects to do a biostatistical analysis in articles using TLC as the definition of malnutrition. CONCLUSION: The focus is on the trends rather than absolutes. As shown in Table 1, whether the albumin cutoff for albumin was 3.0 g/dL, 3.5 g/dL, or 3.9 g/dL, the trend remains the same. Because low albumin before TJAs tends to increase complications, it is recommended to incorporate albumin levels in preoperative workups. Many patients with hip and knee arthritis undergo months of conservative management (eg, physical therapy and corticosteroid injections) before considering surgery, and it would be wise to optimize their nutritional status in this period to minimize the risk of perioperative complications. The physician should use these data to provide informed consent of the increased risk to patients planning to undergo TJAs with elevated malnutrition markers. Because this research is retrospective in nature, albumin should be studied prospectively in hypoalbuminemic and normoalbuminemic patients and their postoperative outcomes should be measured. Regarding transferrin and TLC, future research should help elucidate their predictive value and determine the value of preoperatively optimizing them and their effect in mitigating postoperative complications.

Higher Rate of Early Revision Following Primary Total Knee Arthroplasty in Patients Under Age 55: A Cautionary Tale.

BACKGROUND: There has been an increased number of total knee arthroplasties (TKAs) performed in young and active patients. Although improved materials have decreased the likelihood of early catastrophic wear, concerns remain with the performance and survivorship of TKA implants in this patient population. The purpose this study is to evaluate perioperative complications, patient-reported outcomes, and implant survivorship of TKAs performed in patients under age 55. METHODS: We retrospectively reviewed 4259 primary TKAs performed over a 4-year period. There were 741 TKAs in patients under age 55. The primary outcome of interest was rate of revision at 30 days, 1, 2, and 5-year time points. Secondary outcomes included postoperative transfusion rate, length of stay, rate of deep vein thrombosis/pulmonary embolism, need for manipulation under anesthesia, readmission and reoperation within 30 days, as well as patient-reported outcomes. RESULTS: There were 3518 patients over 55 years and 741 patients under 55 years. Overall, 175 patients required revision (4.1%). Patients under 55 years had significantly higher cumulative revision rate at 1 (3.4% vs 1.8%, P < .001), 2 (5.0% vs 2.4%, P < .001), and 5 years (7.3% vs 3.7%, P < .001). Patients under 55 years had a higher rate of early reoperation. Patients over 55 years required more transfusions and suffered a higher rate of early deep vein thrombosis. Patients over 55 years had significantly greater improvements in Patient Reported Outcome Measurement Information System Global 10 Physical scores at 6 months postoperatively compared to patients under 55 years. CONCLUSIONS: Despite improvements in TKA implants, young and active patients remained at higher risk of early revision compared to older patients. The data should be used to counsel young prospective TKA patients about the early risk of reoperation and non-wear-related complications.

Spinal Fusion Is Associated With Changes in Acetabular Orientation and Reductions in Pelvic Mobility.

BACKGROUND: The importance of spinopelvic motion and its influence on THA stability are well recognized but poorly defined. With dynamic motion, compensatory changes in spine and pelvic positions are required to keep the necessary balance between the axial skeleton and lower extremity to maintain an erect posture. Although prior studies have shown spinal fusions to be an independent risk factor for hip dislocations after primary THA, the direct impact of fusion levels on spinopelvic motion remains unknown. QUESTIONS/PURPOSES: The purposes of this study were (1) to determine if acetabular orientation changes with flexion and extension of the lumbar spine; (2) to determine if the amount of change is different in patients who have undergone spinal fusion at the L5-S1 level; and (3) to identify if the amount of change in acetabular motion is increased in patients who have undergone fusion at additional or other spinal levels. METHODS: We reviewed 100 flexion-extension spine films of patients older than 18 years of age with a history of back pain who had not undergone spinal or hip surgery and compared them with 50 flexion-extension spine films of patients who had undergone lumbar fusion at various levels. These radiographs were acquired between 2012 and 2017 and stored in our institutional radiology database. Only patients with flexion and extension films able to visualize the greater trochanter of the femur were included. For each film, measurements of acetabular version, acetabular version relative to the femoral shaft, lumbar lordosis angle, and sacral slope were digitally performed by two independent observers. Intra- and interrater variability was assessed using Lin's concordance correlation (Rho_c) ranging from 0.59 to 0.91. The change in acetabular version for each patient when going from spinal flexion to extension was compared between patients with no prior spinal or hip surgery and those with prior spinal fusions using a two-tailed t-test. RESULTS: Acetabular version changed -21° as the lumbar spine changed position from flexion to extension in patients without spine surgery (95% confidence interval [CI], -24° to -18°). Acetabular version changed 15° as the lumbar spine changed position from flexion to extension in patients who had undergone prior lumbar spine fusion at all levels (95% CI, -18° to -12°). There was a difference in the change in acetabular version between these two groups of -6° (95% CI, -11° to -1°; p = 0.01). In patients with prior L5-S1 fusion, the change in acetabular version was decreased when compared with patients without prior spine surgery. The change was -10° (95% CI, -15° to -6°), which is less than the change of acetabular version of -21° that we saw in patients without prior spinal fusion (p < 0.01). The difference between these groups was -10° (95% CI, -18° to -3°). Fusion levels above L5 that did not cross the L5-S1 joint did not have a difference in change in acetabular version when compared with patients without surgery with a mean difference of -4° (95% CI, -9° to 2°). CONCLUSIONS: Spinal fusion, specifically at the L5-S1 level, reduces pelvic mobility as the spine moves from flexion to extension. This reduction in motion can reduce the distance to impingement and place patients undergoing THA at risk for dislocation. Further research utilizing three-dimensional imaging modalities and motion analysis can further help define the best hip implant position in these patients. LEVEL OF EVIDENCE: Level III, prognostic study.

Two-Stage Revision Arthroplasty for the Treatment of Prosthetic Joint Infection.

PURPOSE OF REVIEW: To review the diagnosis and treatment of prosthetic joint infection (PJI) with a focus on two-stage revision arthroplasty. The text will discuss different spacer constructs in total knee and total hip arthroplasty and will present clinical outcome data for these various options. RECENT FINDINGS: There is no appreciable difference in infection eradication between mobile and static antibiotic spacers. Mobile spacers have shown improved knee range of motion after second-stage re-implantation. Two-stage revision arthroplasty is the gold standard treatment for PJI. The first stage involves removal of all components, cement, and compromised soft tissues with placement of an antibiotic-impregnated spacer. Spacer options include both mobile and static spacers. Mobile spacers offer maintenance of ambulation and joint range of motion between staged procedures and have shown to be as effective in eradicating infection as static spacers.

Arthroprosthetic cobaltism associated with cardiomyopathy.

Systemic cobaltism related to metal-on-metal total hip arthroplasty has been published in case reports and series with effects on the cardiac, neurologic, endocrine, and immunologic systems. This case report presents a 46-year-old male who underwent bilateral metal-on-metal total hip arthroplasty and subsequently developed cardiomyopathy requiring left ventricular assist device implantation. Intervention with bilateral revision to non-cobalt-containing implants resulted in improved cardiac function. This case report will alert clinicians to the presentation of this rare but devastating complication while also displaying improvement following revision total hip arthroplasty. It is our hope this case will aid in early recognition and intervention of this condition.

Calcium phosphate cement enhances the torsional strength and stiffness of high tibial osteotomies.

PURPOSE: There has been a resurgence in the use of opening wedge high tibial osteotomy (owHTO). Calcium phosphate cement has been shown to improve strength in compression for augmentation of tibial plateau and owHTO fixation. However, knee kinematics includes a torsional load during ambulation, which is as yet unstudied in this model. The purpose of this paper is to investigate the effect of injectable calcium phosphate cement on the biomechanical stability of standard high tibial osteotomy defect with applied torsional load and ultimate stiffness of the supporting construct. METHODS: Testing was performed on 22 bone mineral density-matched and age-matched cadaver specimens. Intact specimens were treated with 10° opening wedge osteotomies, identical surgical techniques as clinically used and fixation provided by iBalance© PEEK implant (Arthrex, Naples FL). Nine specimens were augmented with calcium phosphate injectable cement, Quickset (Arthrex Inc., Naples Fl). Constructs were for construct stiffness, torsional loads to failure, and mechanisms of failure. As a gold-standard comparison group, four samples were tested with a titanium, fixed angle device alone: Contourlock plate (Arthrex Inc., Naples Fl). RESULTS: Peak torque to failure was significantly greater in samples augmented with calcium phosphate bone cement (23.0 ± 9.6 Nm) compared with specimens fixed with PEEK implant alone (18.1 ± 7.3). Construct stiffness in torsion was also significantly improved with bone cement application (349.0 ± 126.8 Nm/°) compared with PEEK implant alone (202.2 ± 153.4 Nm/°) and fixed angle implant system (142.9 ± 74.7 Nm/°). CONCLUSION: Injectable calcium phosphate cement improves the initial maximal torsional strength and stiffness of high tibial osteotomy construct.

Anatomic and Biomechanical Comparison of Traditional Bankart Repair With Bone Tunnels and Bankart Repair Utilizing Suture Anchors.

BACKGROUND: Traditional Bankart repair using bone tunnels has a reported failure rate between 0% and 5% in long-term studies. Arthroscopic Bankart repair using suture anchors has become more popular; however, reported failure rates have been cited between 4% and 18%. There have been no satisfactory explanations for the differences in these outcomes. HYPOTHESIS: Bone tunnels will provide increased coverage of the native labral footprint and demonstrate greater load to failure and stiffness and decreased cyclic displacement in biomechanical testing. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty-two fresh-frozen cadaveric shoulders were used. For footprint analysis, the labral footprint area was marked and measured using a Microscribe technique in 6 specimens. A 3-suture anchor repair was performed, and the area of the uncovered footprint was measured. This was repeated with traditional bone tunnel repair. For the biomechanical analysis, 8 paired specimens were randomly assigned to bone tunnel or suture anchor repair with the contralateral specimen assigned to the other technique. Each specimen underwent cyclic loading (5-25 N, 1 Hz, 100 cycles) and load to failure (15 mm/min). Displacement was measured using a digitized video recording system. RESULTS: Bankart repair with bone tunnels provided significantly more coverage of the native labral footprint than repair with suture anchors (100% vs 27%, P < .001). Repair with bone tunnels (21.9 ± 8.7 N/mm) showed significantly greater stiffness than suture anchor repair (17.1 ± 3.5 N/mm, P = .032). Mean load to failure and gap formation after cyclic loading were not statistically different between bone tunnel (259 ± 76.8 N, 0.209 ± 0.064 mm) and suture anchor repairs (221.5 ± 59.0 N [P = .071], 0.161 ± 0.51 mm [P = .100]). CONCLUSION: Bankart repair with bone tunnels completely covered the footprint anatomy while suture anchor repair covered less than 30% of the native footprint. Repair using bone tunnels resulted in significantly greater stiffness than repair with suture anchors. Load to failure and gap formation were not significantly different.

Proximal Hamstring Repair Strength: A Biomechanical Analysis at 3 Hip Flexion Angles.

BACKGROUND: Proximal hamstring repair for complete ruptures has become a common treatment. There is no consensus in the literature about postoperative rehabilitation protocols following proximal hamstring repair. Some protocols describe bracing to prevent hip flexion or knee extension while others describe no immobilization. There are currently no biomechanical studies evaluating proximal hamstring repairs; nor are there any studies evaluating the effect of different hip flexion angles on these repairs. HYPOTHESIS: As hip flexion increases from 0° to 90°, there will be a greater gap with cyclical loading. STUDY DESIGN: Controlled laboratory study. METHODS: Proximal hamstring insertions were detached from the ischial tuberosity in 24 cadavers and were repaired with 3 single-loaded suture anchors in the hamstring footprint with a Krakow suture technique. Cyclic loading from 10 to 125 N at 1 Hz was then performed for 0°, 45°, and 90° of hip flexion for 1500 cycles. Gap formation, stiffness, yield load, ultimate load, and energy to ultimate load were compared between groups using paired t tests. RESULTS: Cyclic loading demonstrated the least amount of gap formation (P < .05) at 0° of hip flexion (2.39 mm) and most at 90° of hip flexion (4.19 mm). There was no significant difference in ultimate load between hip flexion angles (326, 309, and 338 N at 0°, 45°, and 90°, respectively). The most common mode of failure occurred with knot/suture failure (n = 17). CONCLUSION: Increasing hip flexion from 0° to 90° increases the displacement across proximal hamstring repairs. Postoperative bracing that limits hip flexion should be considered. CLINICAL RELEVANCE: Repetitive motion involving hip flexion after a proximal hamstring repair may cause compromise of the repair.

Rotational and translational stability of different methods for direct acromioclavicular ligament repair in anatomic acromioclavicular joint reconstruction.

BACKGROUND: Many reconstructions of acromioclavicular (AC) joint dislocations have focused on the coracoclavicular (CC) ligaments and neglected the functional contribution of the AC ligaments and the deltotrapezial fascia. PURPOSE: To compare the modifications of previously published methods for direct AC reconstruction in addition to a CC reconstruction. The hypothesis was that there would be significant differences within the variations of surgical reconstructions. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 24 cadaveric shoulders were tested with a servohydraulic testing system. Two digitizing cameras evaluated the 3-dimensional movement. All reconstructions were based on a CC reconstruction using 2 clavicle tunnels and a tendon graft. The following techniques were used to reconstruct the AC ligaments: a graft was shuttled underneath the AC joint back from anterior and again sutured to the acromial side of the joint (group 1), a graft was fixed intramedullary in the acromion and distal clavicle (group 2), a graft was passed over the acromion and into an acromial tunnel (group 3), and a FiberTape was fixed in a cruciate configuration (group 4). Anterior, posterior, and superior translation, as well as anterior and posterior rotation, were tested. RESULTS: Group 1 showed significantly less posterior translation compared with the 3 other groups (P < .05) but did not show significant differences compared with the native joint. Groups 3 and 4 demonstrated significantly more posterior translation than the native joint. Group 1 showed significantly less anterior translation compared with groups 2 and 3. Group 3 demonstrated significantly more anterior translation than the native joint. Group 1 demonstrated significantly less superior translation compared with the other groups and with the native joint. The AC joint of group 1 was pulled apart less compared with all other reconstructions. Only group 1 reproduced the native joint for the anterior rotation at the posterior marker. Group 4 showed significantly increased distances for all 3 measure points when the clavicle was rotated posteriorly. CONCLUSION: Reconstruction of the AC ligament by direct wrapping and suturing of the remaining graft around the AC joint (group 1) was the most stable method and was the only one to show anterior rotation comparable with the native joint. In contrast, the transacromial technique (group 3) showed the most translation and rotation. CLINICAL RELEVANCE: An anatomic repair should address both the CC ligaments and the AC ligaments to control the optimal physiologic function (translation and rotation).