Antiphospholipid Syndrome Increases Postoperative Complications After Total Hip and Knee Arthroplasty.

BACKGROUND: Antiphospholipid syndrome (APS) is a systemic autoimmune condition that predisposes patients to venous thromboembolism (VTE). Although many studies have explored risk factors for VTE after joint reconstructive procedures, the impact of APS is still unclear. MATERIALS AND METHODS: A retrospective cohort study was conducted using TriNetX, a health care database that includes 442,494 patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA). Ninety-day postoperative complications and 1- and 2-year surgical complications were compared between patients with and without preexisting APS. Patients underwent propensity score matching in a 1:1 ratio based on relevant comorbidities. RESULTS: Patients undergoing THA or TKA with APS, compared with those without, had higher rates of deep venous thrombosis (hip: 9.2% vs 6.0%, odds ratio, 1.589, P=.022; knee: 10.5% vs 4.1%, odds ratio, 2.763, P<.001), pulmonary embolism (hip: 6.9% vs 3.6%, odds ratio, 1.992, P=.005; knee: 8.4% vs 3.0%, odds ratio, 2.989, P<.001), and anemia (hip: 24.8% vs 18.6%, odds ratio, 1.447, P=.004; knee: 18.5% vs 13.9%, odds ratio, 1.406, P=.007). Patients undergoing THA with APS also had higher rates of urinary tract infection (5.0% vs 2.8%, odds ratio, 1.842, P=.029) and pneumonia (3.7% vs 1.8%, odds ratio, 2.119, P=.025). APS did not impact rates of surgical complications or revision surgery. CONCLUSION: Overall, APS heightens patients' risk for complications after THA and TKA. Specific anticoagulation protocols and preoperative risk stratification should be implemented to reduce the risk of adverse events. [Orthopedics. 202;4x(x):xx-xx.].

A systematic review of clinical outcomes of pedicled flap repairs of the knee extensor mechanism.

Background Rupture of the extensor mechanism of the knee has severe functional morbidity, and repair can be complicated by infection, allograft degeneration, and recurrent rupture. Techniques of autologous tissue repair utilizing pedicled flaps such as the gastrocnemius offer vascularized methods of reconstruction, with potentially diminished complication rates. The goal of this study was to evaluate the functional outcomes and complications associated with pedicled flap repair of the knee extensor mechanism. Methods A systematic review was conducted following PRISMA guidelines. Publications that focused on local myocutaneous flaps as a means for reconstruction were included. Causes for knee extensor mechanism deficit, flap characteristics, ambulation rate, changes in range of motion pre- and post-operation, and postoperative complications were analyzed. Technique reports including primary suture repairs, synthetic mesh, and allograft use were excluded. Results An initial 119 studies were identified, with final review of 22 observational studies encompassing 128 cases of pedicled flap reconstructions. The gastrocnemius (88.2%, n=113), quadriceps (6.3%, n=8), and a combination of the vastus and gastrocnemius flaps (5.5%, n=7), were the most frequently utilized flaps. Functional outcomes were favorable with 87.2% of patients achieving ambulation without external support. Variability in range of motion outcomes across different flap may be secondary to the patient characteristics as well as extent of initial injury. Conclusions Autologous pedicle flap reconstruction of the knee extensor mechanism emerges as a viable option for cases characterized by extensive defects and insufficient soft tissue coverage, which are not amenable to direct suture repairs or allografts. Postoperative assessments revealed that the majority of patients experienced improved ambulation status, with no instances of deterioration noted among the patients.

Comparing Anesthesia and Surgery Controlled Time for Primary Total Knee and Hip Arthroplasty Between an Academic Medical Center and a Community Hospital: Retrospective Cohort Study.

BACKGROUND: Osteoarthritis is a significant cause of disability, resulting in increased joint replacement surgeries and health care costs. Establishing benchmarks that more accurately predict surgical duration could help to decrease costs, maximize efficiency, and improve patient experience. We compared the anesthesia-controlled time (ACT) and surgery-controlled time (SCT) of primary total knee (TKA) and total hip arthroplasties (THA) between an academic medical center (AMC) and a community hospital (CH) for 2 orthopedic surgeons. OBJECTIVE: This study aims to validate and compare benchmarking times for ACT and SCT in a single patient population at both an AMC and a CH. METHODS: This retrospective 2-center observational cohort study was conducted at the University of Colorado Hospital (AMC) and UCHealth Broomfield Hospital (CH). Cases with current procedural terminology codes for THA and TKA between January 1, 2019, and December 31, 2020, were assessed. Cases with missing data were excluded. The primary outcomes were ACT and SCT. Primary outcomes were tested for association with covariates of interest. The primary covariate of interest was the location of the procedure (CH vs AMC); secondary covariates of interest included the American Society of Anesthesiologists (ASA) classification and anesthetic type. Linear regression models were used to assess the relationships. RESULTS: Two surgeons performed 1256 cases at the AMC and CH. A total of 10 THA cases and 12 TKA cases were excluded due to missing data. After controlling for surgeon, the ACT was greater at the AMC for THA by 3.77 minutes and for TKA by 3.58 minutes (P<.001). SCT was greater at the AMC for THA by 11.14 minutes and for TKA by 14.04 minutes (P<.001). ASA III/IV classification increased ACT for THA by 3.76 minutes (P<.001) and increased SCT for THA by 6.33 minutes after controlling for surgeon and location (P=.008). General anesthesia use was higher at the AMC for both THA (29.2% vs 7.3%) and TKA (23.8% vs 4.2%). No statistically significant association was observed between either ACT or SCT and anesthetic type (neuraxial or general) after adjusting for surgeon and location (all P>.05). CONCLUSIONS: We observed lower ACT and SCT at the CH for both TKA and THA after controlling for the surgeon of record and ASA classification. These findings underscore the efficiency advantages of performing primary joint replacements at the CH, showcasing an average reduction of 16 minutes in SCT and 4 minutes in ACT per case. Overall, establishing more accurate benchmarks to improve the prediction of surgical duration for THA and TKA in different perioperative environments can increase the reliability of surgical duration predictions and optimize scheduling. Future studies with study populations at multiple community hospitals and academic medical centers are needed before extrapolating these findings.

Cefazolin vs Second-line Antibiotics for Surgical Site Infection Prevention After Total Joint Arthroplasty Among Patients With a Beta-lactam Allergy.

Background: Cefazolin is a first-line agent for prevention of surgical site infections (SSIs) after total joint arthroplasty. Patients labeled allergic to beta-lactam antibiotics frequently receive clindamycin or vancomycin perioperatively due to the perceived risk of a hypersensitivity reaction after exposure to cefazolin. Methods: This single-system retrospective review included patients labeled allergic to penicillin or cephalosporin antibiotics who underwent a primary total hip and/or knee arthroplasty between January 2020 and July 2021. A detailed chart review was performed to compare the frequency of SSI within 90 days of surgery and interoperative hypersensitivity reactions (HSRs) between patients receiving cefazolin and patients receiving clindamycin and/or vancomycin. Results: A total of 1128 hip and/or knee arthroplasties from 1047 patients were included in the analysis (cefazolin n = 809, clindamycin/vancomycin n = 319). More patients in the clindamycin and/or vancomycin group had a history of cephalosporin allergy and allergic reactions with immediate symptoms. There were fewer SSIs in the cefazolin group compared with the clindamycin and/or vancomycin group (0.9% vs 3.8%; P < .001) including fewer prosthetic joint infections (0.1% vs 1.9%). The frequency of interoperative HSRs was not different between groups (cefazolin = 0.2% vs clindamycin/vancomycin = 1.3%; P = .06). Conclusions: The use of cefazolin as a perioperative antibiotic for infection prophylaxis in total joint arthroplasty in patients labeled beta-lactam allergic is associated with decreased postoperative SSI without an increase in interoperative HSR.

Neuromuscular electrical stimulation preserves muscle strength early after total knee arthroplasty: Effects on muscle fiber size.

Loss of quadriceps strength after total knee arthroplasty (TKA) is most pronounced acutely but persists long-term, negatively impacting physical function in daily activities. Neuromuscular electrical stimulation (NMES) early after surgery is an effective adjuvant to standard of care rehabilitation (SOC) for attenuating strength loss following TKA, but the mechanisms whereby NMES maintains strength are unclear. This work aimed to determine the effects of early NMES on quadriceps strength and skeletal muscle fiber size 2 weeks after TKA compared to SOC. Patients scheduled for primary, unilateral TKA were enrolled and randomized into SOC (n = 9) or NMES plus SOC (n = 10) groups. NMES was started within 48 h of TKA, with 45-min sessions twice a day for 2 weeks. Isometric quadriceps strength was assessed preoperatively and 2 weeks following TKA. Vastus lateralis muscle biopsies of the involved leg were performed at the same time points and immunohistochemistry conducted to assess muscle fiber cross-sectional area and distinguish fiber types. Groups did not differ in age, body mass index, sex distribution, or preoperative strength. Both groups got weaker postoperatively, but the NMES group had higher normalized strength. After 2 weeks, the group receiving NMES and SOC had significantly greater MHC IIA and MHC IIA/IIX fiber size compared to SOC alone, with no group differences in MHC I fiber size. These results suggest that NMES mitigates early muscle weakness following TKA, in part, via effects on fast-twitch, type II muscle fiber size. This investigation advances our understanding of how adjuvant, early postoperative NMES aids muscle strength recovery.

Two-Stage Revision Total Knee Arthroplasty for Chronic Histoplasma Capsulatum Prosthetic Joint Infection: A Case Report.

CASE: This report describes a histoplasma capsulatum total knee prosthetic joint infection (PJI) in an immunosuppressed patient treated with a 2-stage revision. The diagnosis of PJI was made based on minor criteria, and the causative organism was identified from cultures obtained at the time of explantation. The patient underwent induction with amphotericin B, followed by oral antifungal therapy and a successful 2-stage revision with a hinged prosthesis with an interval of ∼7 months between stage 1 and stage 2. At the most recent follow-up (18 months), she remained clear from infection with planned lifetime antifungal suppression. CONCLUSION: This case report highlights the importance of consideration of atypical organisms when treating immunocompromised patients. Furthermore, this case report documents one of the few cases of histoplasma PJI and provides a successful treatment algorithm to potentially be applied to future cases.

Constraints on Scalar Field Dark Matter from Colocated Michelson Interferometers.

Low-mass (sub-eV) scalar field dark matter may induce apparent oscillations of fundamental constants, resulting in corresponding oscillations of the size and the index of refraction of solids. Laser interferometers are highly sensitive to changes in the size and index of refraction of the main beam splitter. Using cross-correlated data of the Fermilab Holometer instrument, which consists of twin colocated 40-m arm length power-recycled interferometers, we investigate the possible existence of scalar field dark matter candidates in the mass range between 1.6×10^{-12} eV and 1.0×10^{-7} eV. We set new upper limits for the coupling parameters of scalar field dark matter, improving on limits from previous direct searches by up to 3 orders of magnitude.

Interferometric Constraints on Spacelike Coherent Rotational Fluctuations.

Precision measurements are reported of the cross-spectrum of rotationally induced differential position displacements in a pair of colocated 39 m long, high-power Michelson interferometers. One arm of each interferometer is bent 90° near its midpoint to obtain sensitivity to rotations about an axis normal to the plane of the instrument. The instrument achieves quantum-limited sensing of spatially correlated signals in a broad frequency band extending beyond the 3.9-MHz inverse light travel time of the apparatus. For stationary signals with bandwidth Δf>10 kHz, the sensitivity to rotation-induced strain h of classical or exotic origin surpasses CSD_{δh}

Influence of Body Bass Index (BMI) on post-operative Opioid Requirements in Primary Total Joint Arthroplasty Patients.

BACKGROUND: The aim of our study was to evaluate whether an association exists between body mass index (BMI) category and post-operative opioid requirements among primary total joint arthroplasty (TJA) patients. METHODS: We retrospectively reviewed all primary unilateral total hip and total knee arthroplasty (THA/TKA, respectively) cases performed over a two-year period. We evaluated whether a relationship exists between five BMI categories (≤24.9, 25-29.9, 30-34.9, 35-39.9, ≥40) and morphine milligram equivalent (MME) use for total in-hospital, daily in-hospital, and total during six weeks post-discharge. Secondary outcomes included relationship with length of stay, discharge location, opioid refill rate, and pre-operative opioid usage. RESULTS: For all patients undergoing primary TJA, increasing BMI resulted in an incremental increase in post-operative total in-hospital MME use for each successive BMI category when compared to those with BMI ≤24.9 (p < 0.05). This association held true for the THA subset. Within the cohort as a whole, higher categories of BMI were associated with increased length of stay (35-39.9, ≥40), higher odds of needing a refill (30-34.9, 35-39.9, ≥40), and higher odds of discharging to a rehab facility (25-29.9, ≥40) (p < 0.05). There was an increasing proportion of pre-operative opioid use as BMI category increased (p < 0.0001). DISCUSSION/CONCLUSION: BMI category is associated with increased in-hospital opioid requirements among primary TJA patients. Such findings are an important step to better understanding pain control expectations and can help facilitate development of opioid reduction strategies.

The role of metal patch testing in evaluating patients for metallic prosthetic joint failure.

BACKGROUND: Metal allergy may be an uncommon cause of prosthetic joint failure. There exist little data on patch testing to metals in this context and its impact on outcomes of joint revision in these patients. OBJECTIVE: To explore the use and indications for metal patch testing in the evaluation of patients suspected of having metal allergy as a cause of failed joint replacements and to clarify the outcomes of patients revised with alternative metallic joints because of positive patch testing result. METHODS: A retrospective analysis from January 2016 to April 2020 was completed on a patient cohort referred for evaluation of metal hypersensitivity. Charts were reviewed for age, biological sex, referring specialty, patch testing results, joint, revision status, and outcome measures. Biostatistical analysis and descriptive statistics were performed to determine patch testing performance and functional outcome trends among this patient cohort. RESULTS: The sensitivity and specificity of patch testing, in general, are limited when evaluating patients with metallic joint replacements. However, the predictive value of testing seemed to improve with strongly positive patch testing results. Functional outcomes in patients when positive results were used to guide revision prosthesis revealed clinical improvement. CONCLUSION: The attribution of metal allergy or hypersensitivity as a cause of failure in metal prosthetic joint replacement remains unproven. Some patients with positive histories and patch testing results that were used to modify the implanted prosthesis had improved functional outcomes. These results suggest that patch testing may be useful in patients with history of metal sensitivity and prosthetic failure.

Reliability and precision of single frequency bioelectrical impedance assessment of lower extremity swelling following total knee arthroplasty.

Total knee arthroplasty (TKA) is the most common elective orthopedic surgery performed in the United States. Following surgery patients experience significant lower extremity swelling that is related to poor satisfaction with surgery and is hypothesized to contribute to functional decline. However, in practice, precise and reliable methods for measuring lower extremity swelling do not exist. The purpose of this study was to provide reliability and precision parameters of an innovative approach, single frequency bioelectrical impedance assessment (SF-BIA), for measuring post-TKA lower extremity swelling. Swelling in 56 patients (64.3 ± 9.3 years; 29 males) was measured before and after TKA using SF-BIA and circumferential measures (CM). Reliability of the measures was calculated using Intraclass Correlation Coefficients (ICC). Precision of the measures was provided using standard error of the measurement and minimal detectable change (MDC90). Change values between time points for SF-BIA and CM are provided. SF-BIA was found to have greater reliability following surgery compared to CM (ICC = 0.99 vs 0.68). SF-BIA was found to have an MDC90 = 2% following surgery, indicating improved ability to detect minute fluctuations in swelling compared to CM (MDC90 = 6%) following surgery. These results indicate that SF-BIA improves the precision and reliability of swelling measurement compared to CM.

Benefits of direct patient discharge to outpatient physical therapy after total knee arthroplasty.

Purpose: To investigate the effectiveness of home health physical therapy followed by outpatient physical therapy as compared to patients discharged directly to outpatient physical therapy in improving functional performance, strength/activation and residual knee pain outcomes among patients who received a total knee arthroplasty.Materials and methods: A secondary analysis of longitudinal data in which patients with total knee arthroplasty underwent home health physical therapy or were discharged directly to outpatient physical therapy. Main outcome measures included the stair climb test, timed up and go, 6-min walk test, quadriceps and hamstring strength, quadriceps activation and residual knee pain.Results: Patients referred to home health physical therapy prior to outpatient physical therapy demonstrated significantly greater declines in stair climb test (10.3; 95% CI [6.5, 14.1]; t = 5.41; p < 0.0001), timed up and go (2.0; 95% CI [1.0, 3.0]; t = 4.10; p < 0.0001), 6-min walk (53.8; 95% CI [29.4, 78.2]; t = 4.35; p < 0.0001), quadriceps strength (21.7%; 95% CI [19.3%, 24.9%]; t = 2.53; p = 0.01), hamstring strength (44.7%; 95% CI [43.4%, 45.7%], t = 3.17; p = 0.002) and higher residual knee pain (0.53; 95% CI [0.04, 1.03]; t = 2.17; p = 0.03) 1 month after total knee arthroplasty compared to those referred directly to outpatient physical therapy.Conclusions: These findings suggest that patients discharged directly to outpatient physical therapy had a more rapid recovery 1 month after total knee arthroplasty. Additional research is needed to investigate the potential causal relation between care pathways and clinical outcomes following total knee arthroplasty.Implications for rehabilitationTotal knee arthroplasty, typically performed to alleviate end-stage knee osteoarthritis, is the most commonly performed elective surgery in the United States.Despite improvement in pain, objective measurements of functional performance and strength often remain at preoperative levels one year after total knee arthroplasty.Patients discharged directly to higher intensity outpatient physical therapy have a more rapid recovery after total knee arthroplasty compared with those patients who received two weeks of home health prior to undergoing outpatient physical therapy.

Preoperative Activities of Daily Living Dependency is Associated With Higher 30-Day Readmission Risk for Older Adults After Total Joint Arthroplasty.

BACKGROUND: With recent Medicare payment changes, older adults are increasingly likely to be discharged home instead of to extended care facilities after total joint arthroplasty (TJA), and may therefore be at increased risk for readmissions. Identifying risk factors for readmission could help re-align care pathways for vulnerable patients; recent research has suggested preoperative dependency in activities of daily living (ADL) may increase perioperative and postoperative surgical complications. However, the proportion of older surgical patients with ADL dependence before TJA, and the impact of ADL dependency on the frequency and timing of hospital readmissions is unknown. QUESTIONS/PURPOSES: (1) What proportion of older adults discharged home after TJA have preoperative ADL dependency? (2) Is preoperative ADL dependency associated with increased risk of hospital readmissions at 30 days or 90 days for older adults discharged home after TJA? METHODS: This was a retrospective cohort analysis of 6270 Medicare fee-for-service claims from 2012 from a 5% national Medicare sample for older adults (older than 65 years) receiving home health care after being discharged to the community after elective TJA. Medicare home health claims were used for two reasons: (1) the primary population of interest was older adults and (2) the accompanying patient-level assessment data included an assessment of prior dependency on four ADL tasks. Activities of daily living dependency was dichotomized as severe (requiring human assistance with all four assessed tasks) or partial/none (needing assistance with three or fewer ADLs); this cutoff has been used in prior research to evaluate readmission risk. Multivariable logistic regression models, clustered at the hospital level and adjusted for known readmission risk factors (such as comorbidity status or age), were used to model the odds of 30- and 90- day and readmission for patients with severe ADL dependence. RESULTS: Overall, 411 patients were hospitalized during the study period. Of all readmissions, 64% (262 of 411) occurred within the first 30 days, with a median (interquartile range [IQR]) time to readmission of 17 days (5 to 46). Severe ADL dependency before surgery was common for older home health recipients recovering from TJA, affecting 17% (1066 of 6270) of our sample population. After adjusting for clinical covariates, severe ADL dependency was not associated with readmissions at 90 days (adjusted odds ratio = 1.20 [95% CI 0.93 to 1.55]; p = 0.15). However, severe preoperative ADL dependency was associated with higher odds of readmission at 30 days (adjusted OR = 1.45 [95% CI 1.11 to 1.99]; p = 0.008). CONCLUSIONS: Severe preoperative ADL dependency is modestly associated with early but not late hospital readmission after TJA. This work demonstrates that it may important to apply a simple screening of ADL dependency preoperatively so that surgeons can guide changes in care planning for older adults undergoing TJA, which may include participation in preoperative rehabilitation (pre-habilitation) or more aggressive follow-up in the 30 days after surgery. Further research is needed to determine whether severe ADL dependence can be modified before surgery, and whether these changes in dependency can reduce readmission risk after TJA. LEVEL OF EVIDENCE: Level III, therapeutic study.

Metal-on-metal total hip arthroplasty adverse local tissue reaction with intermittent unilateral vascular claudication.

Osteolysis and adverse local soft-tissue reactions are well-documented complications of metal-on-metal prosthetic implants. This case report describes a 68-year-old man who presented to the clinic 10 years after staged bilateral metal-on-metal total hip arthroplasty revisions with the primary complaint of groin pain, intermittent right leg pain, swelling, and muscle cramping while ambulating that resolved with rest. A complete workup was negative for deep venous thrombosis and infection. His symptoms were found to be secondary to an iliopsoas bursal mass externally compressing the femoral vasculature resulting in vascular claudication. He was treated with revision arthroplasty and drainage of the fluid within the iliopsoas bursal effusion with symptomatic resolution.

Peripheral Nociception Is Associated with Voluntary Activation Deficits and Quadriceps Weakness Following Total Knee Arthroplasty.

BACKGROUND: Quadriceps weakness is a hallmark of total knee arthroplasty and is driven by reduced voluntary muscle activation following the surgical procedure. The mechanisms underlying postoperative activation deficits are not well established, although nociception has been implicated via both spinal reflex and supraspinal pathways. The purpose of this study was to assess the role of nociception in postoperative recovery of strength and activation. METHODS: A total of 53 participants were assessed prior to total knee arthroplasty and at 6 weeks postoperatively. Quadriceps strength was measured by maximum voluntary isometric contraction, and activation was measured by the doublet interpolation technique. The pressure-pain threshold was used to measure local sensitization (at the knee joint) and systemic sensitization (at the forearm). Changes in outcomes (strength and activation) were regressed against pressure-pain threshold measurements. Mediation analyses were planned for significant associations to investigate whether deficits in voluntary activation were implicated on a causal pathway between pressure-pain threshold measures and postoperative strength loss. RESULTS: Knee pressure-pain threshold measures were significantly associated with reduced voluntary quadriceps activation (beta = -0.04; p = 0.009) and diminished quadriceps strength after total knee arthroplasty (beta = -0.07; p = 0.001). There was also a mediation effect of voluntary activation on the relationship between the knee pressure-pain threshold and quadriceps strength. After correcting for multiple comparisons, relationships between the forearm pressure-pain threshold and strength and activation did not reach significance. CONCLUSIONS: The measures of local nociceptor sensitization were related to reduced strength and activation following total knee arthroplasty. This is consistent with a causal pathway linking increased firing of knee joint nociceptors to reduced activation and reduced strength. Future randomized studies should investigate whether peripherally directed pain therapies reduce pain while also promoting the recovery of quadriceps strength via an improved capacity for voluntary activation. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Trajectories of functional performance and muscle strength recovery differ after total knee and total hip replacement: a performance-based, longitudinal study.

Total joint replacement is indicated to alleviate pain and disability associated with hip and knee osteoarthritis. Arthroplasty outcomes are typically reported together, or anecdotal comparisons are made between total knee arthroplasty (TKA) and total hip arthroplasty (THA) recovery. Limited data quantifies differences in recovery trajectories, especially with respect to performance-based outcomes. Seventy-nine people undergoing total knee or THA were followed over 6 months. Functional performance was measured using the stair climb test, timed-up-and-go test, and 6-min walk test. Surgical limb isometric strength was also measured. All outcomes significantly declined 1 month after surgery. Participants in the TKA group showed a greater decline in climbing stairs (P < 0.001), timed-up-and-go (P = 0.01), and 6-min walk distance (P < 0.01). Further, the TKA group lost more strength (P < 0.001) and were weaker than those after THA (P < 0.001). Differences in postoperative outcomes between groups at 3 and 6 months were also observed. The TKA group experiences a greater decline in measured outcomes than the THA group, and muscle strength and functional recovery occurred differently in each group. These findings should be considered in rehabilitation priorities after arthroplasty surgery.

The Role of Complete Posterior Cruciate Ligament Release in Flexion Gap Balancing for Total Knee Arthroplasty.

BACKGROUND: The sequence of posterior cruciate ligament (PCL) release in posterior-substituting designs, when performing gap balancing in total knee arthroplasty (TKA), is variable. We hypothesize that early complete PCL release during knee exposure will change the flexion balance to result in a uniform medial-lateral flexion gap symmetry at the time of implant placement. METHODS: Ten cadaveric knees were prepared for TKA using standard medial parapatellar approach. Medial and lateral flexion gaps were measured in the conditions of intact, partial (50%) resection, and full resection of PCL. Measurements were performed with both surgical navigation and a caliper. Flexion gap distances were reported for medial and lateral compartments in the 3 PCL conditions. RESULTS: Medial flexion gap increased after only complete release of the PCL (mean 3.94-5.05 mm). The lateral flexion gap increased as well (mean 4.17-4.67 mm). Complete PCL release resulted in a statistically significant increase in medial flexion gap compared to intact (P = .013) and partially released (P = .012) specimens. No significant differences were noted in lateral flexion gap change. Notable change in medial versus lateral gap (flexion gap symmetry) relationship occurred after just partial PCL release (P = .018). CONCLUSION: Among the 3 PCL states, changes in flexion gap distance were most conspicuous in the medial compartment. This suggests gap balancing performed with incomplete PCL release will not accurately reflect gap distance after eventual PCL removal, thus supporting the hypothesis. It is recommended that the PCL should be released to the fullest extent possible before ligament tensioning for femoral component rotation in posterior-stabilized TKA.

The relationship between lower extremity swelling, quadriceps strength, and functional performance following total knee arthroplasty.

BACKGROUND: The relationships between swelling after total knee arthroplasty (TKA) and quadriceps strength and functional performance are poorly understood. Therefore, the aim of this study was to examine the relationships between lower extremity swelling, measured using bioelectrical impedance assessment (SF-BIA), and quadriceps strength and timed up and go (TUG) times following TKA. METHODS: 53 participants (64 ±â€¯9.5 y/o, 43% male) undergoing primary unilateral TKA were recruited for the longitudinal observational study with repeated measures. Quantities of swelling were examined for contribution to two and six-week outcomes of strength and TUG time using hierarchical regression controlling for age, sex, and the baseline value of the dependent variable. Swelling was assessed using bioelectrical impedance assessment and quantified as the peak level of swelling and cumulative swelling (integral) over the post-TKA time window. Maximum isometric quadriceps strength (MVIC) was measured using a electromechanical dynamometer and participant functional performance measured using the TUG. RESULTS: Neither peak swelling nor cumulative swelling significantly contributed to the variance of two-week quadriceps strength. At six weeks, peak swelling significantly improved the variance in maximal quadriceps strength by an additional four percent (p = 0.05), while cumulative swelling did not significantly contribute. Peak swelling significantly contributed to the variance in two-week (16%) and six-week (five percent) TUG times (p < 0.05), but the cumulative swelling did not. CONCLUSIONS: Peak swelling represents a value of post-TKA swelling that is associated with strength and function. Reducing the peak level of swelling, occurring early after surgery, may improve patient functional recovery. LEVEL OF EVIDENCE: Level II - Prospective observational study.

Correction to: The relationship of pelvic incidence to post-operative total hip arthroplasty dislocation in patients with lumbar fusion.

The original publication of this paper contain an error. The author name "Alan S. McGee Jr" is incorrect for it should have been "Alan W. McGee Jr".