Time from surgery end to discharge following total knee arthroplasty: implications for same day discharge.

BACKGROUND: Understanding the average time from surgery to discharge is important to successfully and strategically schedule cases planned for same day discharge (SDD) for total knee arthroplasty (TKA). The purpose of this study was to (1) evaluate the average time to discharge following unilateral TKA performed in a community hospital and (2) describe patient characteristics and peri-operative factors that may impact SDD. METHODS: This retrospective review included 75 patients having achieved SDD following unilateral TKA between March 2017 and September 2021 at a high-volume multi-specialty community hospital. Time to discharge was calculated from end of surgery, defined as completion of dressing application, to physical discharge from the hospital. Time surgery completed and association with time of discharge was also examined. Pearson's correlations were performed to evaluate the relationship between total time to discharge and patient demographics. RESULTS: The average age for all patients was 66.6 ± 10.9 years (Range: 38 to 86) and average BMI of 29.9 ± 5.6 kg/m2 (Range: 20.4 to 46.3). The average time to discharge was 5.8 ± 1.8 h (range: 2.2 to 10.5 h). Time to discharge was significantly longer for patients finishing surgery prior to noon (6.0 ± 1.8 h), than after noon (4.8 ± 1.4 h, p = 0.046). Total time to discharge was not correlated with age (r = 0.018, p = 0.881) or BMI (r=-0.158, p = 0.178), but was negatively correlated with surgical start time (r=-0.196, p = 0.094). CONCLUSION: An average of six hours was required to achieve SDD following unilateral TKA performed in a community hospital. The time required for SDD was not found to be related to intrinsic patient factors but more likely due to extrinsic factors associated with time of scheduled surgery. To improve success of SDD, focus should be placed on the development of efficient discharge pathways rather than unchangeable intrinsic patient characteristics.

Complications following single-stage bilateral total knee arthroplasty and unilateral procedures: experience of a high-volume community hospital.

INTRODUCTION: The safety of single-stage bilateral total knee arthroplasty (SSBTKA) compared to unilateral total knee arthroplasty (TKA) remains controversial. The present study compares the 90-day postoperative complications encountered following SSBTKA and unilateral TKA in an unselected cohort of patients performed at a high-volume community hospital. MATERIALS AND METHODS: The perioperative electronic medical records of an unselected consecutive cohort of 1032 patients (1345 knees) having undergone unilateral or SSBTKA were reviewed. Ninety-day postoperative complications or need for additional procedures were compared between unilateral and SSBTKA groups. RESULTS: A total of 719 and 313 patients underwent unilateral and SSBTKA, respectively. There were no significant differences in age or BMI between groups. Patients undergoing SSBTKA were more likely to be male (p = 0.019), have longer lengths of stay (p < 0.001) and were less likely to discharge directly home (13.1%) compared to unilateral patients (80.9%) (p < 0.001). Patients undergoing SSBTKA were more likely to require a transfusion (14.7%) compared to unilateral patients (2.2%) (p < 0.001). Interestingly, mortality rate following unilateral TKA (1.7%) was significantly higher than SSBTKA (0.0%) (p = 0.013). There were no significant differences regarding other complications or need for additional procedures within 90 days following surgery. CONCLUSION: SSBTKA did not result in greater complications when compared to unilateral TKA in this particular cohort. As expected, transfusion rates will likely be higher and there will be a greater need for acute inpatient care following surgery for SSBTKA patients.

The influence of mental health on early outcomes following total hip arthroplasty.

BACKGROUND: Poor mental health is difficult to recognize and as a result, its association with recovery from total joint arthroplasty is difficult to assess. The purpose of this study was to investigate the relationship between overall mental health scores and outcomes in the early postoperative period following unilateral total hip arthroplasty (THA). METHODS: This is a retrospective review of prospectively collected data involving 142 patients who underwent primary unilateral THA. Independent variables included patient demographics and preoperative Patient-Reported Outcomes Measurement Information System (PROMIS), Global Physical Health (GPH) and Global Mental Health (GMH) and Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS JR) scores as well as diagnoses of depression or anxiety. Dependent variables included length of stay (LOS), disposition at discharge, narcotic consumption until discharge, 6-week postoperative GPH, GMH and HOOS JR scores and magnitude of change compared to preoperative scores. Preoperative GMH and postoperative outcomes were compared using Pearson correlation coefficient, independent t-tests, Pearson's Chi-Square test, and univariate logistic regression. RESULTS: Patients with preoperative GMH scores below the 25% quartile were less likely to be discharged home and resulted in lower GPH, GMH and HOOS JR scores at 6-week follow-up compared to patients with preoperative GMH scores in the top 25% quartile. However, patients with low preoperative GMH scores demonstrated a greater magnitude of improvement in both the GPH and GMH scores compared to patients in the top 25% quartile. There was no difference in opioid consumption or LOS between either groups. When comparing patients with and without depression/anxiety, no difference was seen in any of the outcomes measured. CONCLUSION: Unilateral THA offers significant improvements in both physical and mental function to patients with hip osteoarthritis and poor mental health, though overall scores remain lower than in those with better mental health.

Do older patients fare worse following unilateral or single stage bilateral total knee arthroplasty?

INTRODUCTION: The safety and benefits of single stage bilateral total knee arthroplasty (SSBTKA) among older patients as compared to unilateral TKA remains controversial. This study aimed to evaluate the influence of age and comorbidities on complications and early outcomes for unilateral and BTKA in patients over and under 70 years of age. MATERIALS AND METHODS: This prospective study compared postoperative complications and early patient-reported outcomes at 6 weeks of 142 unilateral TKA patients (N = 75, ≤ 70; N = 67, > 70) and 89 SSBTKA patients (N = 48, ≤ 70; N = 41, > 70). Patients completed the KOOS JR and PROMIS Global Mental (GMH) and Global Physical Health (GPH) surveys. Knee Society Scores for Knee (KSS-K) and Function (KSS-F) were completed in the clinic. Parametric tests were performed for comparisons of unilateral and BTKA outcomes and complications for patients over and under 70. RESULTS: While patient demographics were similar, patients > 70 had more comorbidities than patients ≤ 70 (p < 0.004). There were no significant differences in postoperative complications or readmissions between age groups or procedures. Unilateral TKA patients > 70 had significantly lower pre- (p < 0.001) and post-operative (p = 0.011) KSS-F scores compared to those ≤ 70. SSBTKA patients > 70 had significantly higher preoperative GMH (p = 0.029), postoperative KSS-K (p = 0.027), KOOS JR scores (p = 0.039) and satisfaction (p = 0.048) compared to those ≤ 70. CONCLUSION: Age did not influence the risk of early postoperative complications. Additionally, the greater improvements in KOOS JR and higher patient satisfaction for SSBTKA patients > 70 suggests that SSBTKA may meet elderly patient expectations and should not necessarily be discouraged due to safety concerns.

A smaller femoral stem is needed for asian females.

BACKGROUND: Current femoral implants are manufactured based on Western anatomical structures and may be too large for smaller physiques, such as those of Asian females. This study reviewed the femoral stem size distribution used in a high-volume total hip arthroplasty (THA) practice and evaluated malalignment in patients receiving a size one implant. MATERIALS AND METHODS: A consecutive cohort of female patients self-reported as Asian (257 patients, 331 hips) or Caucasian (158 patients and 190 hips) were retrospectively evaluated. A single femoral stem type was used in all cases, performed by a single surgeon. Global hip offset (GHO) and leg length difference (LLD) were measured before and 6 weeks following THA. Differences between races were evaluated through Mann-Whitney U tests and chi-squared tests for continuous and categorical variables, respectively. RESULTS: The proportion of size one implants was higher amongst Asian patients (20.5%) than Caucasian patients (2.6%) (p < 0.001). A LLD greater than 6 mm was noted in 24.6% of size one patients and 11.4% of all other sizes (p = 0.010). Varus malalignment occurred in 47.9% of size one patients and 22.1% of all other sizes (p < 0.001). No fractures occurred in size one patients, and nine fractures (one intraoperative and eight post-operative) occurred in all other sizes (p = 0.258). CONCLUSION: The high proportion of size one stems required in Asian females and the higher incidence of LLD > 6 mm and varus malalignment suggest a distinct need for smaller femoral implants, especially for Asian females.

Fixed 6° distal femoral cut consistently achieves neutral alignment for Asians, Caucasians, and Native Hawaiian/Pacific Islanders.

BACKGROUND: Restoration of a neutral mechanical axis (MA) is important to the success of total knee arthroplasty (TKA). While known differences are present between Asians and Caucasians regarding native knee alignment, it is unknown whether such differences exist amongst Native Hawaiian/Other Pacific Islanders (NHPI) or if utilizing a fixed distal femoral cut of 6° can consistently achieve a neutral MA in these minority racial groups. This study examines the preoperative deformities presented by Asians, Caucasians, and NHPI, and the resulting knee alignment achieved following TKA when a fixed 6° distal femoral cut is targeted for all patients. METHODS: Preoperative and postoperative MA was measured from 835 Asian, 447 Caucasian, and 163 NHPI hip-to-ankle radiographs. All patients underwent TKA in which a standard distal femoral cut of 6° valgus was targeted for all patients. Data were evaluated as continuous variables and by groupings of varus (MA < - 3°), valgus (MA > 3°), and neutral (- 3° ≤ MA ≤ 3°) alignment. RESULTS: Preoperative deformity ranged from 38° varus to 29° valgus. The proportion of Asian and NHPI presenting with varus alignment prior to surgery was significantly greater than Caucasian patients in both males (Asians: 80.6%; Caucasians: 67.0%; NHPI: 79.0%, p = 0.001) and females (Asians: 66.1%; Caucasians: 45.7%; NHPI: 63.2%, p < 0.001). There was no difference in the proportion of patients (72-79%) achieving a neutral MA amongst all three racial groups. CONCLUSION: NHPI appear to have similar preoperative deformities to Asians with both groups having significantly more varus alignment than Caucasians. Despite a wide range of preoperative deformity, application of a fixed distal femoral cut of 6° valgus successfully established a neutral MA equally in the majority of patients across all three racial groups.

Reducing transfusion in hip arthroplasty: tranexemic acid diminishes influence of anesthesia administered.

BACKGROUND: The risk of transfusion following total hip arthroplasty (THA) continues to be problematic. The best choice of anesthesia (spinal vs general) and impact of tranexamic acid (TXA) use in reducing transfusions following surgery remain unclear. Therefore, the purpose of this study was to compare rates of blood transfusion following THA via the anterior approach using three different anesthesia protocols with and without TXA. MATERIALS AND METHODS: This retrospective review included 1399 patients (1659 hips), receiving spinal anesthesia (SA) without (248 patients) and with TXA (77 patients), general anesthesia (GA) without (151 patients) and with TXA (171) and general anesthesia with paravertebral block (GA-PVB) and TXA (748 patients). All procedures were performed by a single surgeon. Chi-Squared tests and logistic regression were performed to evaluate the rate and risks of transfusion between groups. RESULTS: Without TXA, transfusion rate with GA (24.5%) was higher than SA (13.4%) (p = 0.004). With TXA, there was no difference in transfusion rates between GA (4.6%), SA (3.9%) or GA-PVB (4.0%). The multivariable regression revealed bilateral (Odds Ratio (OR): 6.473; p < 0.001), female (OR: 2.046; p = 0.004), age (OR: 1.028; p = 0.012) and pre-operative anemia (OR: 2.604; p < 0.001) as increasing the risk of transfusion while use of TXA (OR: 0.168; p < 0.001) significantly reduced transfusion risk. CONCLUSION: The use of TXA during THA via the anterior approach removed the influence of anesthesia type regarding risk of transfusion. The use of TXA may reverse presumed disadvantages of GA alone, potentially facilitating rapid discharge following surgery.

Higher intra-operative narcotic requirements and weakness with quadratus lumborum compared to paravertebral nerve block for total hip arthroplasty.

BACKGROUND: This was a prospective single-blinded study comparing the peri-operative opioid consumption and motor weakness for patients undergoing total hip arthroplasty (THA) with either a Quadratus Lumborum Type 3 Nerve Block (QLB) or a Paravertebral Nerve Block (PVB). METHODS: A consecutive cohort of patients undergoing elective anterior approach (AA) THA by a single high-volume surgeon were randomly assigned an anesthesiologist by the charge anesthesiologist. One anesthesiologist performed all QLBs, and the other six anesthesiologists performed the PVBs. Pertinent data include prospectively collected qualitative surveys from blinded medical personnel, floor nurses, and physical therapists as well as demographic information and post-operative complications. RESULTS: Overall, 160 patients were included in the study divided equally between the QLB and PVB groups. The QLB group had a statistically higher peri-operative narcotic use (p < 0.001), greater intra-operative peak systolic blood pressure (p < 0.001) and respiratory rate (p < 0.001), and higher incidence of post-operative lower extremity muscle weakness (p = 0.040). There were no statistical group differences for floor narcotic use, post-operative hemoglobin levels or hospital length of stay. CONCLUSION: The QLB required greater intraoperative narcotic use and resulted in greater post-operative weakness, however provided nearly equal post-operative pain management and did not adversely affect rapid discharge success. LEVEL OF EVIDENCE: III, Non-randomized controlled cohort/follow-up study.

Influence of obesity and intra-operative imaging guidance technology on acetabular cup positioning in total hip arthroplasty.

BACKGROUND: Accuracy of acetabular cup positioning during total hip arthroplasty (THA) can be improved with intra-operative imaging but may be influenced by body mass index (BMI). This study assessed the influence of BMI (kg/m2) on cup accuracy when using intra-operative fluoroscopy (IF) alone or supplemented with a commercial product. METHODS: This retrospective review included four consecutive cohorts of patients having undergone anterior approach THA with IF alone (2011-2015), IF and Overlay (2015-2016) (Radlink Inc., Los Angeles, CA), IF and Grid (2017-2018) (HipGrid Drone™, OrthoGrid Systems Inc., Salt Lake City, UT) and IF and Digital (2018-2020) (OrthoGrid Phantom®, OrthoGrid Systems, Inc., Salt Lake City, UT). Component placement accuracy was measured on 6-week post-operative weight bearing radiographs and compared between four BMI patient groups (BMI ≤ 25, 25 < BMI ≤ 30, 30 < BMI ≤ 35, and 35 < BMI). Total fluoroscopy times were also recorded directly from the fluoroscopy unit. RESULTS: Abduction angle significantly increased as BMI increased (p = 0.003) with IF alone but no difference was present in groups with guidance technology. Anteversion was significantly different between BMI groups for IF alone (p = 0.028) and Grid (p = 0.027) but was not different in Overlay (p = 0.107) or Digital (p = 0.210). Fluoroscopy time was significantly different between BMI categories for IF alone (p = 0.005) and Grid (p = 0.018) but was not different in Overlay (p = 0.444) or Digital (p = 0.170). CONCLUSION: Morbid obesity (BMI > 35) increases risk for malpositioning of acetabular cups and increases surgical time with IF alone or the Grid. Additional IF guidance technology (Overlay or Digital) increased cup positioning accuracy without decreasing surgical efficiency.

True "outpatient discharge" following single-stage bilateral unicompartmental knee arthroplasty may be unrealistic for most.

BACKGROUND: Single-stage bilateral unicompartmental knee arthroplasty (BUKA) has shown post-operative function and cost benefits over staged bilateral procedures, without increased complications. A rapid discharge protocol at the current study site has reported outpatient discharge for the unilateral procedure exceeding 97%. However, the feasibility of outpatient discharge following BUKA remains unclear. Therefore, the purpose of this study was to determine the success of achieving outpatient (< 24 h) discharge following BUKA, and identify patient variables associated with failure. METHODS: A retrospective chart review was completed for 104 BUKA patients. All patients with bilateral, symptomatic unicompartmental knee arthritis were offered the single-stage procedure. Data collection included patient demographics, discharge status, and disposition location. Independent t tests (continuous) and Chi-squared tests (categorical) determined differences between discharge (outpatient/inpatient) and disposition (home/other) groups. Variables associated with discharge status and location were assessed with multivariable regression. RESULTS: While 96 (92.3%) patients discharged within 24 h, only 63.5% were able to discharge directly home. Patients requiring a longer hospital stay (> 24 h) were more likely to require a pre-operative assistive device (62.5% and 25.0%, p = 0.037) and live alone (37.5 vs 8.3%, p = 0.033). For those discharged within 24 h, living alone significantly increased the risk (odds ratio: 5.800, p = 0.038) of requiring an acute inpatient facility prior to transition home. CONCLUSION: Achieving "true" outpatient discharge is only modestly successful for most BUKA patients, as many required an acute inpatient or short-term rehabilitation facility prior to returning home. BUKA should be differentiated from the unilateral procedure regarding outpatient discharge expectations. LEVEL OF EVIDENCE: III, Case-control study; Retrospective comparative study.

Tempering Expectations for Outpatient Total Knee Arthroplasty for Patients Over 70.

BACKGROUND: Total knee arthroplasty (TKA) is now considered an outpatient procedure, yet advanced age impacts patients' ability to achieve outpatient discharge. Therefore, the purpose of this study is to determine the rate of successful outpatient discharge for TKA patients above 70 years of age and identify potential barriers to success. METHODS: This retrospective review included 352 unilateral TKA patients. The rapid discharge protocol was followed for all patients with the intention of discharge within a 24-hour period. Successful outpatient discharge was classified as ≤24-hour stay and failure was any stay exceeding a 24-hour period in the hospital. Univariate logistic regressions were performed to determine the influence of independent variables on discharge status for all patients and only patients >70 years old. RESULTS: Overall, 46 patients (13%) failed to achieve outpatient discharge, with 35 (76%) patients being ≥70 years old. For patients ≥70, age was not a predictive variable for failure to achieve outpatient discharge (P = .484). However, being female (odds ratio 3.273, 95% confidence interval 1.286-8.325, P = .013) and the use of an assistive walking device (odds ratio 3.031, 95% confidence interval 1.387-6.625, P = .005) remained independent contributors to prolonged hospital stay. CONCLUSION: With patients ≥70 years old more likely to require >24-hour stays, age should be an evaluated metric for justifying higher levels of reimbursement. Although TKA is now considered an outpatient procedure, greater consideration should be given to patients ≥70 years old for higher levels of reimbursement as outpatient discharge is less likely to be successful.

Varus malalignment of short femoral stem not associated with post-hip arthroplasty fracture.

INTRODUCTION: Periprosthetic femoral fractures are an increasingly common post-operative complication of total hip arthroplasty (THA). Though varus malalignment is known to increase fracture risk in standard-length femoral stems, varus malalignment is not as well studied in short stems. Therefore, the purpose of this study was to determine if varus malalignment contributes to early periprosthetic fracture risk in a cementless taper-wedged, short femoral stem. MATERIALS AND METHODS: This retrospective review included 366 consecutive patients (441 THAs) having undergone THA via anterior approach by a single surgeon between July 2014 and December 2016. All patients received the same short, cementless femoral stem. Femoral component angle was measured on 6-week post-THA weight-bearing radiographs, with malalignment defined as a femoral component angle exceeding 0° ± 3°. Periprosthetic femoral fracture and aseptic loosening occurring within 2 years post-THA were recorded. RESULTS: The final data analysis included 426 hips with a mean follow-up time of 32.9 ± 10.2 months. Varus and neutral alignment occurred in 84 (19.6%) and 342 (79.9%) of stems, respectively. Three (0.7%) periprosthetic femoral fractures occurred within 2 years, all occurring in patients with neutrally aligned femoral stems. One (0.2%) stem failed due to aseptic loosening and was malaligned. CONCLUSION: Despite nearly 20% of stems placed in varus alignment, three of the four early complications occurred in a neutrally aligned stem. Based on these results, forceful intraoperative realignment of a short femoral stem with good initial fixation may present an unnecessary increased risk of intraoperative fracture.

Component placement accuracy of two digital intraoperative fluoroscopy supplementation systems in direct anterior total hip arthroplasty.

INTRODUCTION: Intraoperative fluoroscopy (IF) may increase accuracy of component placement when performing direct anterior approach total hip arthroplasty (THA), however, unguided IF continues to produce inconsistent results. Supplementation of IF, with a digital grid (Grid) system or digital overlay (Overlay), may increase component placement accuracy. The purpose of this study was to compare component placement accuracy following THA when IF was supplemented with the Grid or Overlay technique. MATERIALS AND METHODS: Acetabular abduction and anteversion, with leg length discrepancy (LLD) and global hip offset (GHO) were retrospectively evaluated for unilateral and bilateral THA patients from 6-week post-operative radiographs. Target component placement were GHO and LLD < 10 mm, abduction 45° ± 10° and anteversion 15° ± 10° for Overlay and 17° ± 10° for Grid. Differences between the Overlay and Grid were determined by univariate analyses. RESULTS: The Overlay and Grid groups included 178 patients (217 hips) and 262 patients (317 hips), respectively. Target placement with the Overlay and Grid was achieved for GHO in 98.3% and 95.7% of cases (p = 0.108), LLD in 100% and 98.4% of cases (p = 0.121), cup abduction in 98.2% and 97.4% of cases (p = 0.384), and cup anteversion in 97.7% and 71.1% of cases (p < 0.001), respectively. Surgical time was significantly longer in Overlay compared to Grid (Unilateral 77.5 ± 14.1 min and 68.8 ± 12.2; p < 0.001; Bilateral 184.6 ± 27.0 min and 165.5 ± 23.1; p < 0.001, respectively). CONCLUSION: Although no difference was found between the Grid and the Overlay cohorts for LLD, GHO or abduction angle, the Overlay resulted in greater accuracy for acetabular component anteversion angle, with only a slight decrease in surgical efficiency.

Does femoral stem choice influence fracture type or incidence for direct anterior approach total hip arthroplasty?

INTRODUCTION: Despite similar fracture rates, the incidence of intraoperative and post-operative fractures between standard (ST) length and short (SH) femoral stems remains unclear. Therefore, this study compared the incidence of intraoperative and early postoperative fractures between three ST and a single tapered-wedge SH femoral stem. MATERIALS AND METHODS: Data were retrospectively collected on 1113 patients (1306 hips) having undergone total hip arthroplasty, via the anterior approach on a fracture table, between 2014 and 2019. One surgeon completed all ST procedures (314 hips), using one of three implants without discretion. One surgeon completed all SH procedures (992 hips), using one implant design. Differences between ST and SH groups were evaluated by independent t tests (continuous variables) and Chi-square tests (categorical variables). RESULTS: Patients in the SH group were significantly older (p < 0.001) and had a lower body mass index (p = 0.001) compared to the ST group. The total number of fractures was 12 (3.8%) and 14 (1.4%) in the ST and SH groups, respectively. The 12 ST fractures occurred intraoperatively, compared to two (0.2%) in the SH group. The remaining seven (0.7%) SH fractures occurred post-operatively. There was no difference in fracture rate between the three ST designs (p = 0.882). Interestingly, five (0.5%) insufficiency fractures were diagnosed in the SH group. CONCLUSION: The risk of intraoperative and post-operative fractures following anterior total hip arthroplasty may be biased toward ST and SH implants, respectively. These results, along with the presence of five insufficient fractures, identify potential fracture risks and mechanisms for specific implant designs.

Comparison of Component Placement Accuracy Using Two Intraoperative Fluoroscopic Grid Technologies During Direct Anterior Total Hip Arthroplasty.

BACKGROUND: Intraoperative fluoroscopy is beneficial when performing total hip arthroplasty (THA) via the direct anterior approach; however, image distortion may influence component placement. A manual gridding system (MGS) and a digital gridding system (DGS) are commercially available, aimed at visually representing or correcting image distortion. Therefore, the purpose of this study is to compare component placement accuracy following direct anterior approach THA when intraoperative fluoroscopy was supplemented with MGS or DGS. METHODS: A retrospective evaluation of acetabular cup abduction (ABD), leg length discrepancy (LLD) and global hip offset difference (GHO) was completed for consecutive patients from 6 week post-THA weight-bearing radiographs. The predefined target LLD and GHO was <10 mm and ABD target was 45° ± 10°. Differences between MGS and DGS were determined by independent t-tests. RESULTS: The MGS (250 patients, 315 hips) and DGS (183 patients, 218 hips) achieved targeted ABD in 98.7% and 96.8% of cases, respectively, and ABD was significantly lower in the MGS group (45.14 ± 4.03° and 47.01 ± 4.39°, respectively) (P < .001). Compared to MGS, the DGS group averaged significantly higher GHO (3.64 ± 2.44 and 4.45 ± 2.73 mm, respectively, P = .002) but was not significantly different regarding LLD (2.92 ± 2.55 and 3.19 ± 2.46 mm, respectively, P = .275). No significant group difference was noted for percentage within the targeted LLD and GHO; however, 93.5% of DGS and 97.6% of MGS achieved all three (P = .031). CONCLUSION: The use of both the MGS and DGS resulted in consistent component placement within the predefined target zone. Although the MGS appeared to be slightly more consistent, these differences are unlikely to be clinically significant.

Fixed Distal Femoral Cut of 6° Valgus in Total Knee Arthroplasty: A Radiographic Review of 788 Consecutive Cases.

BACKGROUND: In place of the mechanical axis (MA), the use of the variable tibiofemoral angle is frequently used to plan measured resection bony cuts during total knee arthroplasty (TKA). This angle, coupled with operator-dependent variability of intramedullary distal femoral cutting guides, has the potential for catastrophic outcomes. Therefore, a simpler, fixed femoral cut of 6° valgus may be more appropriate when direct measurement of the MA is not possible. METHODS: This was a retrospective study of 788 consecutive TKAs, in which the distal femoral cut was set to 6° valgus. The preoperative and 6-week postoperative MA were measured on hip-to-ankle radiographs. Data were evaluated as a group as well as grouped by preoperative deformity (MA < -3°, -3° < MA < 3°, 3° < MA). RESULTS: Following TKA, MA alignment for all patients was 0.0° ± 2.3° (range, -7.0° to 8.0°). When grouped by pre-TKA alignment, 548 patients were considered varus (MA < -3°), 137 were neutral (-3° < MA < 3°), and 103 patients were valgus (3° < MA). When evaluating the post-TKA alignment achieved in the 3 groups, neutral alignment (-3° < MA < 3°) was established in 86.5% of varus patients, 86.1% of neutral patients, and 82.5% of valgus patients. CONCLUSION: A standard distal femoral cut of 6° resulted in a neutral MA in 86% of patients. While no single technique will be correct for all deformities, in the absence of sophisticated preoperative planning aids, this simple technique could provide a more reliable surgical technique than the measured tibiofemoral angle.

Standard Radiographs Are Not Sufficient for Assessing Knee Mechanical Axis in Patients With Advanced Osteoarthritis.

BACKGROUND: The use of standard radiographs, and measured tibiofemoral angle (TFA), to assess lower extremity alignment is commonly practiced despite limited knowledge of its relationship to the mechanical axis (MA), as measured on hip-to-ankle (HTA) radiographs. This study assessed the predictive accuracy of previously developed equations, developed gender-specific regression equations using predictors from standard radiographs, and the clinical effectiveness of these equations in a large sample of cases using HTA radiographs as a gold standard. METHODS: The MA was measured on HTA radiographs, whereas TFA and femoral angle were measured on standard radiographs in 788 cases diagnosed with knee osteoarthritis. RESULTS: Multiple regression analyses indicated that TFA, femoral angle, and height were the strongest factors associated with the predicting MA, accounting for 83% of the variance for men and 86% for women, but were able to predict only the actual MA within ±3° in 66% of men and 69% of women. When applied to previously reported regression equations with similar results, the best predicative accuracy obtained within ±3° was 61% and 63% of men and women, respectively. CONCLUSION: Standard radiographs are not sufficient for determining MA, and HTA radiographs should be used while making surgical decisions aimed at correcting alignment to within ±3° or for assessing alignment post-total knee arthroplasty. In addition, surgical alignment outcomes reported in previous research using standard radiographs should be viewed with caution.

Children's Uncertain Responses when Testifying about Alleged Sexual Abuse in Scottish Courts.

This study examined the uncertain responses of 56 alleged sexual abuse victims, aged 5-17 years, testifying in Scottish criminal court trials. Don't know/remember ground rules were explained to 38% of the children and each child reported uncertainty in response to 15% of the questions on average. Uncertain responding was associated with expressions of resistance and confusion, questioning context (proportionally more regarding substantive than non-substantive issues), question content (least to disclosure-focused questions), utterance type (more to directives, particularly those posed by defense lawyers; more to recall-based than recognition prompts), and age (children in mid-adolescence were less likely to respond uncertainly than those who were either older or younger). There were no associations between expressions of uncertainty and ground rule administration, or with whether or not the question focused on central rather than peripheral details about the alleged crimes. Findings highlight concerns surrounding preparatory procedures to help witnesses, especially adolescents, indicate uncertainty when testifying. Copyright © 2017 John Wiley & Sons, Ltd.

Challenging the Credibility of Alleged Victims of Child Sexual Abuse in Scottish Courts.

This study examined the effects of credibility-challenging questions (n = 2,729) on 62 5- to 17-year-olds' testimony in child sexual abuse cases in Scotland by categorizing the type, source, and content of the credibility-challenging questions defense lawyers asked and assessing how children responded. Credibility-challenging questions comprised 14.9% of all questions asked during cross-examination. Of defense lawyers' credibility-challenging questions, 77.8% focused generally on children's honesty, whereas the remainder referred to specific inconsistencies in the children's testimony. Children resisted credibility challenges 54% of the time, significantly more often than they provided compliant responses (26.8%). The tendency to resist was significantly lower for questions focused on specific rather than general inconsistencies, and peripheral rather than central content. Overall, children resisted credibility challenges more often when the aim and content of the question could be understood easily. As this was a field study, the accuracy of children's responses could not be assessed. The findings suggest that credibility-challenging questions that place unrealistic demands on children's memory capacities (e.g., questions focused on peripheral content or highly specific details) occur frequently, and that juries should be made aware of the disproportionate effects of such questioning on the consistency of children's testimony.

The Interaction of Fatigue and Potentiation Following an Acute Bout of Unilateral Squats.

A prior conditioning resistance exercise can augment subsequent performance of the affected muscles due to the effects of post-activation potentiation (PAP). The non-local muscle fatigue literature has illustrated the global neural effects of unilateral fatigue. However, no studies have examined the possibility of acute non-local performance enhancements. The objective of the study was to provide a conditioning stimulus in an attempt to potentiate the subsequent jump performance of the affected limb and determine if there were performance changes in the contralateral limb. Using a randomized allocation, 14 subjects (6 females, 8 males) completed three conditions on separate days: 1) unilateral, dominant leg, Bulgarian split squat protocol with testing of the exercised leg, 2) unilateral, dominant leg, Bulgarian split squat protocol with testing of the contralateral, non-exercised leg and 3) control session with testing of the non-dominant leg. Pre- and post-testing consisted of countermovement (CMJ) and drop jumps (DJ). The exercised leg exhibited CMJ height increases of 3.5% (p = 0.008; d = 0.28), 4.0% (p = 0.011; d = 0.33) and 3.2% (p = 0.013; d = 0.26) at 1, 5, and 10 min post-intervention respectively. The contralateral CMJ height had 2.0% (p = 0.034; d = 0.18), 1.2% (p = 0.2; d = 0.12), and 2.1% (p = 0.05; d = 0.17) deficits at 1, 5, and 10 min post-intervention respectively. Similar relative results were found for CMJ power. There were no significant interactions for DJ measures or control CMJ measures. The findings suggest that PAP effects were likely predominant for the exercised leg whereas the conditioning exercise provided trivial magnitude although statistically significant neural impairments for the contralateral limb.