Small change in the arithmetic hip-knee-ankle angle during unicompartmental knee arthroplasty improves early postoperative functional outcomes.

INTRODUCTION: The optimal lower-limb alignment after unicompartmental knee arthroplasty (UKA) remains controversial. This study aimed to investigate the optimal lower-limb alignment for functional improvement in the early post-UKA period. We hypothesized that a small change (Δ) in the arithmetic hip-knee-ankle (aHKA) angle during surgery would result in better postoperative knee function. MATERIALS AND METHODS: This single-centered, retrospective study analyzed 91 patients (91 knees) who underwent UKA from April 2021 and December 2022. Preoperative and postoperative standing whole-leg radiographs were used to evaluate the mechanical HKA angle and aHKA angle. The aHKA angle was calculated from the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). We defined restored aHKA angle as a postoperative aHKA angle within ± 3° of the preoperative aHKA angle. Functional improvement was evaluated using the preoperative and one-year postoperative Knee Society Scoring 2011 (KSS 2011). A multivariate regression analysis was performed to investigate the optimal lower-limb alignment for functional improvement. RESULT: Postoperative restored aHKA angle (p = 0.020) was the only significant factor for improved KSS 2011 scores. Postoperative restored aHKA angle was obtained in 64 patients (70%). ΔMPTA (p < 0.001) and ΔLDFA (p = 0.037) were significant factors associated with a postoperative restored aHKA angle. CONCLUSIONS: UKA restores the native knee, including resurfacing constitutional alignment and medial collateral ligament tension. Minimal change in the aHKA angle during UKA improves the functional outcomes of the knee during the early postoperative period, consistent with the minimally invasive surgical concept of UKA.

Joint-preserving effect and patient-reported outcomes of transtrochanteric curved varus osteotomy for osteonecrosis of the femoral head.

BACKGROUND: This study assessed the hip survival rate and patient-reported outcome measures (PROMs) of transtrochanteric curved varus osteotomy (CVO) for osteonecrosis of the femoral head (ONFH) compared with those of conservative management. METHODS: The CVO group comprised 32 consecutive patients (39 hips) who underwent CVO for ONFH between 2000 and 2011. The conservative group consisted of 36 consecutive patients (37 hips) who were managed conservatively for at least 1 year after collapse and who had ONFH classified by the Japanese Investigation Committee of Health and Welfare as type B or C1, for which CVO is indicated. Kaplan-Meier analysis of hip survival used any ONFH-related therapeutic surgery as the endpoint. PROMs were evaluated for all patients with surviving hips and radiographs available at the latest follow-up. RESULT: The 10-year hip survival rate in the CVO group was 86.7%, which was significantly higher than the 51.0% 5-year survival rate in the conservative group (p < 0.0001). The Oxford Hip Score and UCLA Activity Score were significantly better in the CVO group without joint space narrowing than in the conservative group, with no significant differences between the CVO group with joint space narrowing and the conservative group. CONCLUSION: CVO could preserve hip joints more effectively than conservative follow-up after collapse, although the presence of joint space narrowing could reduce satisfaction levels even in patients with long-term hip survival.

Synovial-tissue resident macrophages play proinflammatory functions in the pathogenesis of RA while maintaining the phenotypes in the steady state.

Synovial tissue-resident macrophages (STRMs) maintain normal joint homeostasis in a steady state. However, it is unclear whether STRMs still play homeostatic roles or change the functions in the joint of rheumatoid arthritis (RA), where infiltrating peripheral blood monocyte-derived macrophages (PBMoMs) play proinflammatory roles. In the present study, we examined changes in the phenotypes and functions of STRMs in response to RA-related stimuli in vitro. STRMs were prepared from non-inflammatory osteoarthritis (OA) joint synovium, which is histologically indistinguishable from normal joint synovium. PBMoMs were prepared and used for comparison. After stimulation with plate-bound IgG, which mimics anti-citrullinated protein antibody immunocomplex formed in RA joints, or with combinations of RA-related inflammatory mediators, namely tumor necrosis factor-α (TNF-α) and prostaglandin E2 or interferon-γ, PBMoMs downregulated surface markers and genes associated with anti-inflammatory macrophages, and upregulated cytokine and marker genes of proinflammatory macrophages in RA. On the other hand, STRMs hardly changed the expression of surface molecules and marker genes but altered the pattern of cytokine gene expression after stimulation like PBMoMs. Furthermore, in vitro stimulated STRMs promote proinflammatory functions of cocultured synovial fibroblasts. Thus, STRMs might play proinflammatory roles in RA joints, while maintaining their phenotypes in the steady state.

Predictors of physical activity recovery after total hip arthroplasty: a prospective observational study.

PURPOSE: Little is known about the changes and the factors in physical activity as following total hip arthroplasty (THA). There are potential discrepancies between subjective and objective measurements of physical activity. Thus, our porpose is to compare objective and subjective measurements of activity levels in patients undergoing THA preoperatively, three months and one year following surgery, and investigated the factors that predicts the objective activity level after THA. METHODS: This prospective observational study included 42 patients with unilateral symptomatic hip osteoarthritis who underwent THA. The objective activity level (step counts, sit-to-stands, and upright time) by using a tri-axial accelerometer, PRO (Oxford hip score; OHS and University of California, Los Angeles activity score; UCLA score), and muscle volume around the hip joint by using preoperative computed tomography were measured. RESULTS: The number of steps, OHS, and UCLA score before, at three months, and one year after THA averaged 5092, 6532, and 6545 steps, 30.3, 43.0, and 44.2 points, and 3.4, 4.8, and 4.6 points, respectively, with significant postoperative increases (P < 0.05). No significant difference was found between three months and one year postoperatively. In multivariate analysis, younger age and higher preoperative contralateral gluteal medius volume were the predictors of higher postoperative step counts (P < 0.05). CONCLUSIONS: Physical activity, including step counts, OHS, and UCLA score increased significantly until three months after unilateral THA. Early surgical intervention before contralateral muscle declines and preoperative rehabilitation including contralateral side may additionally improve postoperative activity levels.

Contralateral Hip Abductor Muscle Strength Associated with Comfort of Getting into and out of the Car after Total Hip Arthroplasty.

There are no studies that have investigated the characteristics of car use across THA patients, including those who do not drive. This study aimed to evaluate, in THA patients, (1) postoperative car usage, (2) comfort while entering and exiting a car, and (3) whether lower limb muscle strength affects action comfort. One hundred seventy-two post-THA patients completed the questionnaire in 2020, along with assessments of hip abductor and knee extensor muscle strength before surgery and at discharge. Patients whose overall comfort level was judged as comfortable were defined as the comfort group; others were placed in the discomfort group. Of the 172 patients, 161 reported car usage at a mean of 5.6 years after THA. Of these, 114 and 47 patients were placed in the comfort and discomfort groups, respectively. Patients in the discomfort group were three times more likely to experience discomfort using the contralateral side door than the surgical side door, and about twice as many patients experienced discomfort when entering as when exiting. Lower preoperative contralateral hip abductor muscle strength was the only independent predictor for discomfort. The take-home messages were that prevention of contralateral-side weakness may improve comfort during the action after THA.

The sourcil roundness index is a useful measure for quantifying acetabular concavity asphericity.

This study aimed to clarify the clinical utility of the sourcil roundness index (SRI), a novel index for quantifying the asphericity of the acetabular concavity, by determining (1) the difference in the SRI between dysplastic and normal hips and (2) the correlation between the SRI and radiographic parameters of hip dysplasia. We reviewed standing anteroposterior pelvic radiographs of 109 dysplastic and 40 normal hips. The SRI was determined as the ratio of the distance from the medial edge of the sourcil to the most concave point of the acetabular sourcil (A) to the distance from the medial to the lateral edge of the sourcil (B). The formula for SRI is (A/B) × 100-50 (%), with an SRI of 0% indicating a perfectly spherical acetabulum, and higher SRI values indicating a more aspherical shape. The median SRI was greater in patients with hip dysplasia than in normal hips (5.9% vs. - 1.4%; p < 0.001). Furthermore, the median SRI was greater in the severe dysplasia subgroup (18.9%) than in the moderate (3.5%) and borderline-to-mild (- 1.3%) dysplasia subgroups (p < 0.05). Quantification of acetabular concavity asphericity by the SRI showed that dysplastic hips had a more lateral acetabular concave point than normal hips, and that the severity of hip dysplasia had an effect on the acetabular concavity asphericity.

Evaluation of the anterior acetabular coverage with a false profile radiograph considering appropriate range of positioning.

This study aimed to (1) set a reference value for anterior center edge angle (ACEA) for preoperative planning of periacetabular osteotomy (PAO), (2) investigate the effects of pelvic rotation and inclination from false profile (FP) radiographs on the measured ACEA, and (3) determine the "appropriate range of positioning" for FP radiograph. This single-centered, retrospective study analyzed 61 patients (61 hips) who underwent PAO from April 2018 and May 2021. ACEA was measured in each digitally reconstructed radiography (DRR) image of the FP radiograph reconstructed in different degrees of pelvic rotation. Detailed simulations were performed to determine the "appropriate range of positioning" (0.67 < ratio of the distance between the femoral heads to the diameter of the femoral head < 1.0). The vertical-center-anterior (VCA) angle was measured on the CT sagittal plane considering the patient-specific standing positions, and its correlation with the ACEA was investigated. The reference value of ACEA was determined by receiver operating characteristic (ROC) curve analysis. The ACEA measurement increased by 0.35° for every 1° pelvic rotation approaching the true lateral view. The pelvic rotation with the "appropriate range of positioning" was found at 5.0° (63.3-68.3°). The ACEA on the FP radiographs showed a good correlation with the VCA angle. The ROC curve revealed that an ACEA < 13.6° was associated with inadequate anterior coverage (VCA < 32°). Our findings suggest that during preoperative PAO planning, an ACEA < 13.6° on FP radiographs indicates insufficient anterior acetabular coverage. Images with the "appropriate positioning" can also have a measurement error of 1.7° due to the pelvic rotation.

"Grand-piano sign" as a femoral rotational indicator in both varus and valgus knees: a simulation study of anterior resection surface in total knee arthroplasty.

PURPOSE: The "Grand-piano sign" is a popular indicator of the appropriate rotational alignment of the femoral component during total knee arthroplasty (TKA). The aim of the study was to investigate the shape of the anterior femoral resection surface of varus and valgus knees. METHODS: A cohort of 80 varus knees and 40 valgus knees (hip-knee-ankle angle > 2° for varus and < - 2° for valgus knees) matched for age, sex, height, body weight, and KL grade was made using propensity score matching. Virtual TKA was performed using 3 patterns of components (anterior flange flexion angles of 3°, 5°, and 7°). The anterior femoral resection surface was evaluated for 3 patterns of rotational alignments: parallel to the surgical epicondylar axis (NR, neutral rotation), 3° internal rotation (IR), and 3°external rotation (ER) relative to the surgical epicondylar axis. In each anterior femoral resection surface, the vertical height of medial and lateral condyles was measured, and the ratio of the medial to the lateral height (M/L ratio) was evaluated. RESULTS: The M/L ratio in NR for both varus and valgus knees was 0.57 to 0.64, with no significant difference between the cohorts (p value > 0.05). The M/L ratio showed a similar pattern of increasing at IR and decreasing at ER in both varus and valgus knees. The variation in the M/L ratio with malrotation in valgus knees was smaller than in varus knees. CONCLUSION: During TKA, the anterior femoral resection surface was similar in varus and valgus knees; however, the variation with malrotation was smaller in valgus knees than in varus knees. TKA for valgus knees requires precise surgical technique and careful intraoperative assessment. LEVEL OF EVIDENCE: IV, Case series.

Protocol for the RETHINK study: a randomised, double-blind, parallel-group, non-inferiority clinical trial comparing acetaminophen and NSAIDs for treatment of chronic pain in elderly patients with osteoarthritis of the hip and knee.

INTRODUCTION: In patients with chronic pain, oral analgesics are essential treatment options to manage pain appropriately, improve activities of daily living abilities and achieve a higher quality of life (QOL). It is desirable to select analgesics for elderly patients based on comparative data on analgesic effect and risk of adverse events; however, there are few comparative studies so far. The purpose of this study is to determine whether the efficacy and safety of acetaminophen are non-inferior to non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of chronic pain associated with osteoarthritis of the hip and knee in elderly patients. METHODS AND ANALYSIS: This study is a multicentre, randomised controlled, double-blind, parallel-group study to compare the analgesic effect and adverse events between acetaminophen or NSAIDs (loxoprofen or celecoxib). A total of 400 elderly patients with osteoarthritis of the hip and knee will be recruited from five institutions in Japan. Patients of 65 years or older with osteoarthritis-related pain will be registered and randomly assigned to acetaminophen, loxoprofen or celecoxib with 2:1:1 allocation. The primary endpoint is change in the Brief Pain Inventory (BPI) item 3 (worst pain) score from baseline to week 8. The secondary endpoints are BPI item 3 score change from baseline to week 4, health-related QOL measured by Short Form-8 Health Survey, and occurrence of adverse events including gastrointestinal disorders and abnormal liver function. Data will be analysed in accordance with a predefined statistical analysis plan. ETHICS AND DISSEMINATION: This study protocol was approved by the Kyushu University Hospital Certified Institutional Review Board for Clinical Trials on 28 January 2021 (KD2020004) and the chief executive of each participating hospital. The results of the study will be submitted to international peer-reviewed journals, and the main findings will be presented at international scientific conferences. TRIAL REGISTRATION NUMBER: jRCTs071200112.

Similar short-term KOOS between open-wedge high tibial osteotomy and total knee arthroplasty in patients over age 60: A propensity score-matched cohort study.

OBJECTIVES: The purpose of the present study was to evaluate improvement in the Knee Injury and Osteoarthritis Outcome Score (KOOS) after open-wedge high tibial osteotomy (HTO) in comparison with total knee arthroplasty (TKA) in cohorts over age 60 matched by pre-operative age, gender, body mass index (BMI), hip-knee-ankle angle (HKAA), KOOS sub-scores, and osteoarthritis (OA) grade. METHODS: Propensity score matching was performed between 162 HTO patients and 134 TKA patients. When calculating the propensity score by multivariate logistic regression analysis, the following pre-operative confounders were included: age, gender, BMI, HKAA, KOOS sub-scores, and OA grade. Consequently, a total of 55 patients were included in each group. The Student's t-test was used to analyse differences in the post-operative KOOS sub-scores between groups. RESULTS: After propensity score matching, all matched pre-operative valuables were identical, with no significant differences between the HTO and TKA groups. None of the post-operative KOOS sub-scores at 1 year after surgery showed a significant difference between the HTO and TKA groups. Both groups demonstrated significant and comparable post-operative improvement in every KOOS sub-score. CONCLUSIONS: In patients over age 60, there was no significant difference in short-term pain relief and improvements in activity and quality of life between HTO and TKA after propensity score matching including pre-operative age, KOOS sub-scores, and OA grade. HTO is a joint preservation procedure that is valid for knee OA even in individuals over age 60.

Vitamin D status-associated postoperative complications in patients with hip dysplasia after periacetabular osteotomy: A case-control study.

OBJECTIVES: This study aimed to clarify the relationship between vitamin D status and complications after periacetabular osteotomy. METHODS: A total of 46 hips of 39 patients (3 men and 36 women; mean age at surgery, 41.0 years; mean postoperative follow-up duration, 63 months) were reviewed to obtain the following information: patients' serum 25-hydroxyvitamin D [25(OH)D] status, prevalence of postoperative delayed union of osteotomy sites in the greater trochanter (DUGT) and ischiopubic stress fractures (IPSFs), and risk factors. RESULTS: The mean serum 25(OH)D level was 11.9 ng/ml. DUGT and IPSF were found in four (10.3%) and three (7.7%) patients, respectively. Serum 25(OH)D levels ≤ 11 ng/ml were significantly associated with DUGT in female patients (p = .02). Serum 25(OH)D levels ≤ 9 ng/ml and smoking were significantly associated with IPSF (p = 0.01 and 0.02, respectively). Overall, 21.7% of patients with serum 25(OH)D levels ≤ 11 ng/ml developed at least one complication; no complications occurred when serum 25(OH)D levels were >11 ng/ml. CONCLUSION: Severe vitamin D deficiency was highly prevalent in relatively young patients. Vitamin D deficiency and smoking were independent risk factors for postoperative complications. Proactive supplementation is advisable to reduce postoperative complications, especially in patients with serum 25(OH)D levels ≤ 11 ng/ml.

The influence of bone marrow edema for the assessment of the boundaries of necrotic lesions in patients with osteonecrosis of the femoral head.

This study aimed to investigate the influence of bone marrow edema (BME) for the assessment of the boundaries of necrotic lesions using unenhanced and contrast-enhanced (CE) magnetic resonance (MR) images in patients with osteonecrosis of the femoral head (ONFH). We retrospectively reviewed 72 consecutive hips in 55 patients of ONFH that were Association Research Circulation Osseous (ARCO) stage III or higher and underwent both unenhanced and contrast-enhanced MR imaging between January 2005 and February 2016. The degree of extension of BMEs, and the boundaries of the necrotic lesions were compared using unenhanced and CE MR images on both mid coronal and mid oblique-axial slices. Forty-two percent of the coronal T1 images, 40% of the coronal fat-saturated T2 images, and 48% of the oblique-axial T1 images showed differences in the boundaries of necrotic lesion, by comparison with those of CET1-weighted MR images. The boundaries of necrotic lesions were clearly detected in all hips on CE coronal slices and 97% of all hips on CE oblique-axial slices. The BME grade in the difference group was significantly higher than in the non-difference group on the coronal plane (P = 0.0058). There were significant differences between the BME grade and duration from the onset of hip pain to MR imaging examination. Multivariate analyses revealed that the duration from the onset to MR imaging examination in both coronal (P = 0.0008) and oblique-axial slices (P = 0.0143) were independently associated with differences in the boundary of necrotic lesion between T1 and CET1-weighted MR images. Our findings suggest that unenhanced MR image may be insufficient for a precise assessment of the boundaries of the necrotic lesions for ONFH cases in the early phase of subchondral collapse due to the diffuse BME.

Multiple Imputation to Salvage Partial Respondents: Analysis of the Forgotten Joint Score-12 After Total Hip Arthroplasty.

BACKGROUND: Missing responses are common when Asian patients complete the Forgotten Joint Score-12 (FJS-12), which is widely used to evaluate total hip arthroplasty (THA). We aimed to provide orthopaedic researchers with a solution for handling missing values in such patient-reported outcome measures (PROMs). METHODS: Patients who had undergone primary THA between 1998 and 2016 (n = 1,021) were investigated in 2020. The FJS-12 and 9 other PROMs, including questions related to Asian lifestyle activities, were administered. Risk factors for missing FJS-12 items were investigated. Partial respondents were matched with complete respondents; then, in each pair, the items not completed by the partial respondent were deleted from the responses of the complete respondent. Predictive mean matching (PMM) was performed in an attempt to recover the deleted items, using 65 sets of imputation models. After the missing values had been imputed, we explored patient characteristics that affected the FJS-12, using data from all complete and partial respondents. RESULTS: A total of 652 patients responded to the survey (393 complete and 193 partial respondents). Partial respondents were older, more often female, and less active. Older respondents were more likely to skip items involving the bed, while those who reported a better ability to sit in the seiza style (traditional Japanese floor sitting) were more likely to skip items about chair sitting. The imputed FJS-12 value exhibited excellent reliability (intraclass correlation coefficient for agreement with the true scores, 0.985). FJS-12 values of complete respondents were significantly higher than those of respondents with 4 to 11 missing items (51.6 versus 32.8, p < 0.001). Older age was associated with higher FJS-12 values, which was revealed only via analysis of the multiply imputed data sets (p < 0.001). CONCLUSIONS: Analysis of only complete FJS-12 responses after THA resulted in a nonresponse bias, preferentially excluding older, female, and less active individuals and those with a traditional floor living style. Multiple imputation could provide a solution to scoring and analyzing PROMs with missing responses by permitting the inclusion of partial respondents. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Preoperative Virtual Total Knee Arthroplasty Surgery Using a Computed Tomography-based 3-dimensional Model With Variation in Reference Points and Target Alignment to Predict Femoral Component Sizing.

Background: The purpose of this study was to investigate the size differences of 19 different femoral component placements from the standard position in total knee arthroplasty using 3-dimensional virtual surgery. Methods: Three-dimensional bone models were reconstructed from the computed tomography data of 101 varus osteoarthritic knees. The distal femoral bone was cut perpendicular to the femoral mechanical axis (MA) in the coronal plane. Twenty different component placements consisting of 5 cutting directions (perpendicular to MA, 3° and 5° extension relative to MA [3°E-MA and 5°E-MA, respectively], and 3° and 5° flexion relative to MA [3°F-MA and 5°F-MA, respectively]) in the sagittal plane, 2 rotational alignments (clinical epicondylar axis [CEA] and surgical epicondylar axis [SEA]), and 2 rotational types of anterior reference guide (central [CR] and medial [MR]) were simulated. Results: The mean anteroposterior dimension of femur ranged from 54.3 mm (5°F-MA, SEA, CR) to 62.5 mm (5°E-MA, CEA, MR). The largest and smallest differences of anteroposterior dimension from the standard position (3°F-MA, SEA, and CR) were 7.1 ± 1.3 mm (5°E-MA, CEA, and MR) and -1.2 ± 0.2 mm (5°F-MA, SEA, and CR), respectively. Multiple regression analysis revealed that flexion cutting direction, SEA, and CR were associated with smaller component size. Conclusions: The femoral component size can be affected easily by not only cutting direction but also the reference guide type and the target alignment. Our findings could provide surgeons with clinically useful information to fine-tune for unintended loose or tight joint gaps by adjusting the component size.

Analysis of Factors That Influence Patient Satisfaction After Periacetabular Osteotomy: An Asian Cohort Study.

Periacetabular osteotomy (PAO) is an effective joint-preserving procedure for developmental dysplasia of the hip. However, some patients report dissatisfaction after PAO. Because patient satisfaction is increasingly used as a health care quality metric, it is important to gain a better understanding of factors associated with patient satisfaction after PAO. The goal of this study was to investigate patient satisfaction among a cohort of Asian patients undergoing PAO. This study included 227 Asian patients who had undergone PAO at our institution between 1998 and 2016. The study participants completed a questionnaire assessing patient satisfaction, reasons for dissatisfaction, and postoperative Oxford Hip Score (OHS) and University of California, Los Angeles (UCLA), activity scale score. Based on their satisfaction levels, the participants were divided into 4 subgroups, and their demographic characteristics and postoperative patient-reported outcomes were compared. Of the 227 patients, 190 expressed satisfaction that correlated with OHS-pain, OHD-activities of daily living, and UCLA activity scale scores. Primary reasons for dissatisfaction after PAO were persistent pain (24 of 49, 49%), functional limitations (14 of 49, 29%), stiffness around the hip (4 of 49, 8%), unmet expectations (4 of 49, 8%), conversion to total hip arthroplasty (2 of 49, 4%), and complications (1 of 49, 2%). Multivariate analysis showed that preoperative Kellgren-Lawrence grades 1 and 3 were the significant predictive factors for satisfaction and dissatisfaction, respectively. The potential for lower patient satisfaction associated with Kellgren-Lawrence grade 3 because of persistent pain and functional limitations postoperatively suggests that consideration of preoperative severity of osteoarthritis could enhance patient satisfaction after PAO. [Orthopedics. 2022;45(5):297-303.].

Tapered wedge stems decrease early postoperative subsidence following cementless total hip arthroplasty in Dorr type C femurs compared to fit-and-fill stems.

BACKGROUND: To compare the degree of stem subsidence between two different femoral component designs and to determine the risk factors associated with stem subsidence after cementless total hip arthroplasty (THA) in Dorr type C femurs. METHODS: We retrospectively reviewed 104 consecutive hips in 100 patients with Dorr type C proximal femoral morphology who underwent primary cementless THA using a fit-and-fill stem or a tapered wedge femoral stem at our institution between January 2012 and June 2021. A fit-and-fill stem was used in 55 hips and a tapered wedge stem was used in 49 hips. Radiologically, the distance between the apex of the major trochanter and the stem shoulder were measured at three different time points (immediately [0W], one week [1W], and six weeks [6W] after surgery) and the degrees of stem subsidence were assessed by comparing the distance between 0 and 1W, 1W and 6W, and 0W and 6W, respectively. RESULTS: The mean degree of stem subsidence (0W vs. 1W) was 0.24 mm (standard deviation [SD] 0.36) in the fit-and-fill stem group, and 0.23 mm (SD 0.41) in the tapered wedge stem group. There was no significant difference between the two groups (P = 0.4862). However, the mean degrees of subsidence were significantly higher in the fit-and-fill stem group (1W vs. 6W, 0.38 mm [SD 0.68]; 0W vs. 6W, 0.65 mm [SD 0.87]) than in the tapered wedge stem group (1W vs. 6W, 0.16 mm [SD 0.32]; 0W vs. 6W, 0.24 mm [SD 0.38]) (P < 0.05 for both). In addition, the rates of > 3 mm subsidence (in which instability can be observed) were 18.2% (10 of 55 hips) and 2.0% (1 of 49 hips), respectively. There was also a significant difference between the two stems (P = 0.0091). Multivariate analysis demonstrated that fit-and-fill stem was a risk factor for > 3 mm subsidence after THA in Dorr type C femurs (P = 0.0050). CONCLUSION: Our findings suggest that the tapered wedge stem is more suitable for Dorr type C femurs than the fit-and-fill stem to avoid early postoperative subsidence in cementless THA.

Short-term results of total hip arthroplasty using a tapered cone stem for patients with previous femoral osteotomy.

PURPOSE: In total hip arthroplasty (THA) for patients with previous femoral osteotomy, we hypothesized that a tapered cone stem may be an option due to the altered morphology of the proximal femur. The purpose of this study was to assess the short-term results of THA after femoral osteotomy using a tapered cone stem, and to identify issues that require further attention. METHODS: Twenty-two hips in 21 consecutive patients who underwent THA after femoral osteotomy using a Wagner Cone tapered cone stem were retrospectively reviewed, with a mean follow-up period of 34.4 (range, 24-50) months. Clinical information was obtained from medical records. On preoperative radiographs, the Dorr type was classified based on the anteroposterior cortical index. On postoperative radiographs, the degree of stem subsidence and the stem location with the highest canal fill ratio were assessed. RESULTS: The mean Harris hip score significantly improved from 55.2 at baseline to 84.8 at final follow-up. Radiologically, stem subsidence (>3 mm) was observed in seven hips, and it stabilized within 1 year after THA in all cases. In five of seven hips with stem subsidence, the highest postoperative canal fill ratio was observed in the distal third of the stem. The proportions of males and Dorr type A were significantly higher among hips with stem subsidence than among those without. During the follow-up period, no hips showed implant loosening or required revision surgery. CONCLUSIONS: The occurrence of stem subsidence should be noted when using Wagner Cone stems for Dorr type A femurs after femoral osteotomy.

Does accelerometer-based portable navigation provide more accurate and precise cup orientation without prosthetic impingement than conventional total hip arthroplasty? A randomized controlled study.

PURPOSE: This prospective randomized controlled study examined whether accelerometer-based navigation resulted in more accurate or precise cup orientation than a conventional mechanical guide. We used a simulation to evaluate how cup orientation affected potential hip range of motion (RoM) and freedom from prosthetic impingement. METHODS: Sixty hips were randomly allocated 1:1 to accelerometer-based portable navigation or conventional guidance. Procedures were performed through a standard posterolateral approach and combined anteversion technique. Cup inclination, cup anteversion, and stem anteversion were measured using computed tomography (CT). Using CT-based simulation, we evaluated impingement-free potential RoM and the proportion of hips with potential RoM required for daily activities. RESULTS: Absolute cup inclination and anteversion error averaged 4.3° ± 3.2° and 4.4° ± 2.9° for the navigation cohort and 5.6° ± 3.7° and 5.7° ± 4.2° for the conventional cohort, with no significant differences. Navigation resulted in significantly less variation in anteversion error than the conventional guide (p = .0049). Flexion, internal rotation (IR) at 90° of flexion, extension, and external rotation (ER) averaged 123° ± 12°, 46° ± 13°, 50° ± 10°, and 73° ± 23°, respectively, in the navigation cohort and 127° ± 10°, 52° ± 14°, 45° ± 10°, and 63° ± 12°, respectively, in the conventional cohort (p = .15, .15, .03, and .03, respectively). Flexion > 110°, IR > 30° at 90° of flexion, extension > 30°, and ER > 30° were achieved by 93%, 90%, 100%, and 100% of hips, respectively, in the navigation cohort and 97%, 93%, 97%, and 100% of hips, respectively, in the conventional cohort, with no significant differences. CONCLUSIONS: Cup anteversion with the navigation system was more precise, but not more accurate, than with the conventional guide. The navigation cohort exhibited greater potential extension and ER than the conventional cohort, but no significant difference in impingement within the potential RoM required for daily activities. TRIAL REGISTRATION NUMBER: 29036. Date of registration: November 14, 2017.

Evaluation of optimal implant alignment in total hip arthroplasty based on postoperative range of motion simulation.

BACKGROUND: Dislocation after total hip arthroplasty is a frequent cause of revision surgery. This study was performed to determine the optimal implant alignment in total hip arthroplasty by simulating the postoperative range of motion. METHODS: All operations were performed via posterolateral approach using combined anteversion of the stem and cup technique. Maximum range of motion without implant impingement was simulated in 79 replaced hips using postoperative computed tomography and the achievement of the required range of motion defined by previous studies was assessed. Optimal cup and stem alignment for impingement-free range of motion were statistically determined using the receiver operator coefficient curve. FINDINGS: Cup inclination and anteversion, stem anteversion, and combined anteversion were 37.6°, 20.1°, 26.2°, and 46.3°, respectively. Maximum range of motion in flexion, extension, internal rotation at 90° of flexion, and external rotation were 131.8°, 42.3°, 56.4°, and 64.5°, respectively. Flexion >110°, extension >30°, internal rotation >30° at 90° of flexion, and external rotation >30° were fulfilled by 96%, 86%, 92%, and 96% of all replaced hips, respectively. Optimal implant alignment for impingement-free range of motion was 34°-43° of cup inclination, 18°-26° of cup anteversion, 17°-29° of stem anteversion, and 35°-56° of combined anteversion. Both cup and stem anteversion showed significant relationship with postoperative range of motion. INTERPRETATION: Surgeons could gain valuable insights into optimal cup and stem alignment to perform postoperative range of motion simulations.

Transverse osteotomy closer to tibial plateau is associated with larger postoperative change in valgus laxity after open-wedge high tibial osteotomy.

PURPOSE: To identify the factors impacting changes in valgus laxity between before and after open-wedge high tibial osteotomy (OW-HTO) using quantitative valgus stress radiographs. METHODS: A total of 40 knees from 38 patients who underwent OW-HTO were assessed. The study population comprised 14 men and 24 women, with a mean age of 61.5 years. Valgus stress radiographs before and 1 year after OW-HTO were performed using a Telos device. The difference between pre- and postoperative joint line convergence angle (JLCA) was expressed as ΔJLCA (post-pre). As indicators of the proximal detachment of superficial medial collateral ligament (sMCL) on radiographs, two distances were defined: the distance from the level of the osteotomy starting point to the tangent line of the proximal tibial plateau (Distance A), or to the medial edge of the proximal tibial plateau (Distance B). Correlations between ΔJLCA and radiographic parameters or KOOS sub-scores were assessed using Spearman's rank correlation coefficient analysis. Receiver operator curves were generated to evaluate the predictive strength of the significant factor for an increase in ΔJLCA > 1°. RESULTS: Pre-operative OA severity consisted of Kellgren-Lawrence grade 2 (n = 18), 3 (n = 16), and 4 (n = 6). The average ΔJLCA (post-pre) was 0.5°, and ranged from - 1.4° to + 3.0°. The maximum systemic measurement error and limits of agreement were 0.07° and 0.20°, respectively. There were significant correlations between ΔJLCA and Distance A (36.9 ± 3.9 mm, R = - 0.46, p = 0.002), between ΔJLCA and Distance B (39.9 ± 4.0 mm, R = - 0.49, p = 0.001). The cut-off value for Distance A was determined to be 35 mm below the tibial plateau; the AUC was 0.804, with a sensitivity of 0.75 and a specificity of 0.82. Distance B correlated strongly with Distance A (R = 0.96, p < 0.001). There was no significant correlation between ΔJLCA and KOOS sub-scores 1 year after OW-HTO. CONCLUSIONS: Transverse osteotomy closer to tibial plateau was associated with larger valgus joint laxity postoperatively. This finding implies that sMCL proximal detachment, which was related to the level of the osteotomy starting point on the proximal tibia, potentially affected postoperative valgus laxity. LEVEL OF EVIDENCE: IV.