Callus formation after total hip arthroplasty using a short tapered-wedge stem.

OBJECTIVE: The incidence of periprosthetic fractures after total hip arthroplasty using a short tapered-wedge stem is high. Callus formation preceding this fracture, which indicates postoperative stress fracture around the stem, has been reported. However, previous studies on postoperative callus are limited. Hence, the current study aimed to evaluate the prevalence and risk factors of postoperative callus after total hip arthroplasty with a short tapered-wedge stem. MATERIALS AND METHODS: This retrospective study included 127 patients who underwent total hip arthroplasty using a cementless short tapered-wedge stem. The depth of stem insertion was measured as the distance from the lateral corner of the stem to the most medial point of the lesser trochanter along the body axis. Postoperative callus was defined as a bridging callus on the lateral femoral cortex at the distal end of the porous coating of the stem. Plain radiography was performed before surgery and immediately and at 1, 3, and 6 months after surgery to assess postoperative callus. Univariate and multivariate logistic regression analyses were performed to identify the risk factors for PC. RESULTS: In total, 60 (47.2%) of 127 patients presented with postoperative callus. Multivariate logistic regression analysis with postoperative callus as the dependent variable revealed that the stem depth at 1 month after total hip arthroplasty (odds ratio, 1.14; 95% confidence interval, 1.04-1.24, p = 0.002) was a significant and independent risk factor of postoperative callus. CONCLUSION: Deep insertion of a short tapered-wedge stem is a risk factor for postoperative callus.

Non-metastatic hip fractures surgery in patients with active cancer: benefit and risk.

PURPOSE: Although rare, non-metastatic proximal femoral fracture (PFF) can develop in patients with active cancer. However, little data are available regarding the risks and benefits of surgical treatment in such patients. The purpose of his study was to investigate the risks and benefits of surgical treatment of PFF in patients with and without cancer. METHODS: We retrospectively examined the medical records of all patients treated for PFF, excluding those with pathological fracture, at our hospital from July 2013 to December 2020. The patients were divided into two groups; The active cancer group and the standard group. We investigated in both groups about surgical and medical complications during the perioperative period, walking ability two weeks postoperatively, and one-year postoperative mortality rate. RESULT: After the inclusion and exclusion criteria, 39 patients in the active cancer group and 331 patients in the standard group were finally investigated. There were no statistically significant differences between the two groups. The complication rate did not appear statistical significance between two groups (16.7% in active cancer group vs 10.7% in standard group: p = 0.272). Walking ability was also similar in two groups. Mortality rate at one year was significantly higher in the active cancer group. (41.2% in active cancer group vs 6.0% in standard group: p < 0.05). CONCLUSION: Although the active cancer group had a higher mortality rate at one year, which was influenced by the prognosis of the cancer, the benefits of surgical intervention, such as regaining walking ability, were the same in patients with and without active cancer.

Highly accurate acoustical prediction using support vector machine algorithm for post-operative subsidence after cementless total hip arthroplasty.

PURPOSE: Acoustic analysis has recently been applied to cementless total hip arthroplasty (THA). The aim of this study was to develop a machine learning algorithm to predict post-operative subsidence with high accuracy. METHODS: The acoustic parameters of the hammering sounds during a broaching procedure for 62 hips in 55 patients who underwent THAs with cementless taper-wedged stem were analysed. The patient's basic background such as age, sex, height, weight and body mass index, the femoral morphological parameters and the hammering sound characteristics of 24 features of normalised sound pressure (nSP) in 24 frequency ranges were applied to binary classification using a support vector machine using the following models with different features: model A, nSP only; model B, nSP + patients' basic background features; model C, nSP + patients' basic background features + femoral morphological parameters. RESULTS: In 62 hips with 310 hammering sounds, 12 hips (19.4%) showed ≥ 3 mm of post-operative subsidence; hence, 60 hammering sounds were set as positive examples and 250 hammering sounds were set as negative examples. The AUC was very high in all models. The accuracy (AUC/sensitivity/specificity/positive predictive value/negative predictive value/accuracy rate) of each model was as follows: model A, 0.963/0.656/0.996/0.980/0.925/0.934; model B, 0.9866/0.675/1.000/1.000/0.928/0.937 and model C, 0.998/0.750/1.000/1.000/0.950/0.957. CONCLUSION: In this study, we developed a high-accuracy machine learning algorithm for post-operative subsidence using acoustic parameters and additional pre-operative features. Our results represent a step toward the realisation of acoustic monitoring to avoid the complication in cementless THA.

Risk factors for over-telescoping in reverse oblique intertrochanteric fractures.

PURPOSE: Postoperative over-telescoping (OT) with lag screws is often observed in reverse oblique intertrochanteric fractures. This study aimed to clarify the risk factors of OT in patients with reverse oblique intertrochanteric fractures. METHODS: Electronic medical records of patients diagnosed with reverse oblique intertrochanteric fractures using plain radiography who underwent operative fixation with an intramedullary nail between August 2013 and December 2019 were reviewed. Patients were classified into two groups according to the Futamura classification: lateral wall pattern (LW) and reverse oblique pattern (RO). The incidence of OT in the LW and RO groups was compared. Also, we compared the incidence of OT for each reduction type in the LW group. RESULTS: Twenty patients had LW, and nine had RO. OT was observed in eight fractures (42.1%) in the LW group but not in the RO group. The incidence of OT was significantly higher in the LW group than in the RO group (P = 0.0261). Among the 19 fractures with LW, OT was observed in 7 of 10 and 1 of 9 fractures with postoperative reduction in the intramedullary and extramedullary or anatomical types, respectively. In the LW group, the incidence of OT was significantly higher in fractures with postoperative reduction in the intramedullary type than in those of the extramedullary or anatomical type (P = 0.0198). CONCLUSION: Our study showed that the incidence of OT was significantly higher in LW than in RO and that postoperative reduction in the intramedullary type in LW was a risk factor for OT.

Blood cobalt ion level in patients with different sizes of cobalt/chrome femoral head with the Accolade TMZF stem.

BACKGROUND: Corrosion of stem-cobalt/chromium (Co/Cr) head interface and subsequent systemic Co ion complication have been a clinical concern after total hip arthroplasty (THA). The aim of this study is to investigate correlation between type of femoral head and blood Co ion level. METHODS: One hundred four patients with THA using accolade TMZF and Co/Cr femoral head (32-mm; 55 cases, 36-mm; 20 cases, dual mobility system (DM) with 22.2 or 28-mm inner head; 29 cases) participated in this study, and blood Co ion concentration test was performed in patients a minimum of four years after THA. RESULTS: DM group was significantly older than 32-mm and 36-mm group (DM: 73.9 ± 4.6, 32-mm: 63.3 ± 8.5, 36-mm: 66.8 ± 10.5). The median (interquartile range) blood Co concentration of each group was 32-mm group 0.26 µg/L (0.69), 36-mm group; 0.21 µg/L (0.30); and DM group 0.21 µg/L (0.13). There was a significant difference of Co concentration between DM and 32-mm group (p = 0.023). Abnormal values of the blood Co concentration (> 1 µg/L) were observed in the 32-mm group; 12 cases (21.8%), 36-mm group; 2 cases (10.0%); and DM group; 0 case (0%) (p = 0.018). CONCLUSIONS: Co blood concentration differed among the different sizes of Co/Cr femoral head. THA using DM is a safe option with low risk of complication from cobalt ion if it is used for elderly patients.

Acoustic characteristics of broaching procedure for post-operative stem subsidence in cementless total hip arthroplasty.

PURPOSE: Avoiding stem subsidence is crucial for achieving better outcome for cementless total hip arthroplasty (THA). The aim of this study was to develop a prediction model for the incidence of post-operative stem subsidence using full quantitative acoustic parameters in hammering sound during the broaching procedure and to assess the accuracy of this prediction model. METHODS: The acoustic parameters of the hammering sounds during a broaching procedure for 55 hips in 49 patients who underwent THAs with cementless taper-wedged stem were analysed. The stem subsidence was assessed at one month post-operatively, and the relationship between the acoustic parameters and the value of stem subsidence was investigated. RESULTS: The average stem subsidence was 2.15 ± 2.91 mm. The subsidence 3 mm or more was observed in eleven hips (20%), and 5 mm or more was observed in seven hips (12.7%). Basic patient's characteristics, preoperative femoral morphology and immediate post-operative canal fill ratio and stem alignment were not significantly related to the volume of stem subsidence. Nine acoustic parameters were significantly correlated with the value of subsidence. The prediction model for post-operative subsidence using only acoustic parameters during broaching procedure was established, and this model showed a positive prediction value of 100% and a negative prediction value of 90.6% for post-operative stem subsidence at 5 mm or more. CONCLUSION: Post-operative stem subsidence can be predicted by using acoustic parameters of the hammering sound during the broaching procedure. Our results suggest that we are at the start of a new era in which novel and innovative smart technologies can be used to assist in orthopaedic surgery.

Radiation-induced segregation in a ceramic.

Radiation-induced segregation is well known in metals, but has been rarely studied in ceramics. We discover that radiation can induce notable segregation of one of the constituent elements to grain boundaries in a ceramic, despite the fact that the ceramic forms a line compound and therefore has a strong thermodynamic driving force to resist off-stoichiometry. Specifically, irradiation of silicon carbide at 300 °C leads to carbon enrichment near grain boundaries, whereas the enrichment diminishes for irradiation at 600 °C. The temperature dependence of this radiation-induced segregation is different from that shown in metallic systems. Using an ab initio informed rate theory model, we demonstrate that this difference is introduced by the unique defect energy landscapes present in the covalent system. Additionally, we discover that grain boundaries in unirradiated silicon carbide grown by chemical vapour deposition are intrinsically carbon-depleted. The inherent grain boundary chemistry and its evolution under radiation are both critical for understanding the many properties of ceramics associated with grain boundaries.

Use of Dual Mobility Acetabular Component and Anterior Approach in Patients With Displaced Femoral Neck Fracture.

BACKGROUND: Although the antidislocation effect of total hip arthroplasty (THA) via the direct anterior approach (DAA) with dual mobility cup (DMC) for displaced femoral neck fracture (FNF) has already been reported, the clinical result of DMC-DAA-THA for displaced FNF in terms of mortality, complications, and walking ability are still unclear. METHODS: 106 cases with DMC-DAA-THA for displaced FNF were investigated of dislocation; perioperative complications; 3-, 6-, and12-month mortality rate; and pre/early postoperative walking ability. The walking ability was stratified into the following four categories: (1) use of a wheelchair (no walking), (2) walking alongside a support (including walkers designed for the elderly), (3) walking using one stick, and (4) unaided walking. RESULTS: There was no dislocation withing one-year postoperative. The 3-, 6-, and 12-month mortality rate was 2.8%, 4.7%, and 5.7%. Total complications occurred in 14 cases (14.7%). Although there was no revision surgery, two cases (1.9%) of intraoperative fracture treated without additional fixation, and one case of postoperative fracture was occurred. Among patients with preinjury walking category 2, 3, and 4 (total 94 cases), the number of patients who recovered same walking category at two-week postoperation was 56 cases (59.6%). CONCLUSIONS: Our study demonstrated that DMC-DAA-THA for displaced FNF offered quick recovery of walking ability with no dislocation and low one-year mortality rate. We believe that the combination of early postoperative recovery due to the minimal invasiveness of the DAA and decreased dislocation rate due to increased range of motion by DMC and adequate soft tissue tension by DAA contributed to null dislocation.

Does increased diameter of metal femoral head associated with highly cross-linked polyethylene augment stress on the femoral stem and cortical hypertrophy?

PURPOSE: Cortical hypertrophy (CH) after total hip arthroplasty (THA) is thought as a process of femoral cortical functional adaptation against the stem. However, no study has been performed to investigate the association between CH and femoral head size. The purpose of this study is to investigate the factors related to femoral CH around the cementless stem after THA. METHODS: THAs in 31 patients using 36-mm metal head and as a control, age-matched 62 THAs with 32-mm metal head have been analyzed. Radiographs were reviewed at four years to determine cortical thickness change from immediate post-operative one. Pre-operative and immediate post-operative radiographs were used to calculate the femoral morphology, canal fill ratio, stem alignment, and femoral and acetabular offset. Univariate and multivariate logistic regression analyses were performed to identify the risk factors for CH. RESULTS: Patients with a 36-mm metal head had a significantly higher rate of severe CH (P = 0.001) than those with a 32-mm metal head. The multivariate logistic regression analysis with dependent variables of CH showed that the use of a 36-mm metal head had a significantly positive effect on CH. The odds ratio of a 36-mm metal head in mild CH was 2.517 (95% confidence interval, 1.032-6.143; P = 0.043), and that in severe CH was 8.273 (95% confidence interval, 2.679-25.551; P = 0.000). Age and the canal flare index were weakly and negatively influenced by mild CH. CONCLUSIONS: The use of a 36-mm metal head was the dominant risk factor for CH.

Pelvic mobility before and after total hip arthroplasty.

BACKGROUND: Pre-operative evaluation of pelvic motion using the sacral slope (SS) has been proposed for risk assessment of dislocation after total hip arthroplasty (THA). The purposes of this study were to elucidate the statistical characteristics of pre-operative and post-operative pelvic mobility and investigate the relationship between pre-operative spinopelvic factors and post-operative pelvic mobility. METHODS: Eighty-six patients with osteoarthritis were assessed. The parameters evaluated were lumbar lordosis angle and the SS in the standing and sitting preo-peratively and post-operatively. The pelvic mobility was defined as the difference in the SS between standing and sitting. The presence of osteoarthritis in the contralateral hip, spondylolisthesis, vertebral compression fracture and lumbar scoliosis was investigated. RESULTS: The median (interquartile range) pre-operative and post-operative pelvic mobility was 19.0 (13.75-27.0) and 16.0 (10.0-25.25), respectively, with significant difference. The pre-operative SS while standing and pre-operative pelvic mobility were associated with post-operative pelvic mobility (r = 0.409, P < 0.05 and r = 0.533, P < 0.05). The multivariate linear regression analysis showed that the following factors contributed to post-operative pelvic mobility: incidence of osteoarthritis in the contralateral hip, lumbar scoliosis, pre-operative SS while standing and pre-operative SS while sitting. CONCLUSION: The pre-operative and post-operative pelvic mobility is not equal and ranges widely among patients. In addition to assessment of pre-operative pelvic mobility, other pre-operative spinopelvic factors may also influence post-operative pelvic mobility, such as the SS while standing and sitting, the condition of the contralateral hip and the presence of scoliosis. Risk assessment for dislocation using these pre-operative factors may be useful before THA.

Bowing-head sign: rare but detectable in pre-catastrophic hip implant failure.

Recently, catastrophic failure (i.e., dissociation between the metal femoral head and stem due to stem neck deformation) after total hip arthroplasty (THA) has been reported. Early detection of this complication is very important, because it is accompanied by an increased cobalt concentration in the body, which might influence systemic conditions such as heart failure and immune system diseases. However, early detection of stem neck deformation is considered as difficult. In most cases in the literatures, the diagnosis was made at the time of acute dissociation. We report a case of early detection of stem neck deformation with the 'Bowing-head sign' before acute dissociation. The patient is a 71-year old woman complained of a clicking sensation in the right hip during regular follow-up after THA with a 32-mm cobalt/chromium head with polyethylene insert for osteoarthritis performed 7 years previously. The plain radiograph showed that the angle between the metal femoral head and the axis of the stem neck was not perpendicular ('Bowing-head sign'). Dynamic evaluation under fluoroscopy showed movement of the stem neck in the metal femoral head with hip abduction and adduction. Laboratory data showed abnormal serum cobalt (6.3 µg/L, normal < 1 µg/L) and chromium (3.8 µg/L, normal < 5 µg/L) levels. Considering those radiographic findings, deformation of the stem neck due to trunnionosis was diagnosed, and elective revision surgery was performed without any complications. Plain radiographs after THA should be assessed with attention to this complication, 'Bowing-head sign' must not be overlooked.

Is actual surgical experience reflected in virtual reality simulation surgery for a femoral neck fracture?

INTRODUCTION: A virtual reality simulator developed for orthopaedic and trauma surgical training has been introduced. However, it is unclear whether the experiences of actual surgery are reflected in virtual reality simulation surgery (VRSS) using a simulator. The aim of this study is to investigate whether the results in VRSS differ between a trauma expert and a trauma novice. METHODS: In Group A (expert), there are ten orthopaedic trauma surgeons and in Group B (novice) ten residents within 2 years after medical school graduation. VRSS for a femoral neck fracture using Hansson hook-pins (Test 1) and Hansson twin hook plate (Test 2) was performed. The parameters evaluated were total procedure time (s), fluoroscopy time (s), number of times X-ray was used (defined by the number of times the foot pedal was used), number of retries in guide placement, and final implant position. RESULTS: In Test 1, the averages of four parameters (distance to posterior cortex (p = 0.009), distal pin distance above lesser trochanter (p = 0.015), distal pin hook angular error (p = 0.004), and distal pin tip distance to centre (lateral) (p = 0.015)) were significantly different between Groups A and B. In Test 2, no parameters in a mean were significantly different between groups, but seven parameters in a variance (guide wire distance to joint surface (p = 0.0191), twin hook length outside barrel (p = 0.011), twin hook tip distance to centre (lateral) (p = 0.042), twin hook distance to centre of lateral cortex (lateral) (p = 0.016), plate end alignment error (lateral) (p = 0.027), guide wire angle with lateral cortex (front) (p = 0.024), and 3.2-mm drill outside cortex (p = 0.000)) were significantly different between groups. In Test 1, Group B showed significantly longer fluoroscopy time than Group A (p = 0.044). In Test 2, Group B showed significantly fewer instances of X-ray use than Group A (p = 0.046). CONCLUSIONS: Our study showed that the experiences of actual surgery are reflected in the result of VRSS using the simulator.

A biomechanical study of sacroiliac rod fixation for unstable pelvic ring injuries: verification of the "within ring" concept.

PURPOSE: The aim of this study was to compare the fixation power of sacroiliac rod fixation (SIRF), which was developed based on our original "within ring" concept to exclude the lumbar vertebra from the fixation range, and spinopelvic fixation (SPF) in a biomechanical experiment. METHODS: SPF and SIRF were applied to the posterior element in four bones each with the pelvic ring fracture model (AO/OTA classification 61-C1.3). A 300-N axial force was loaded on the fifth lumbar vertebra of the simulated pelvis. Then the stiffness (N/m) and deformation (mm) of SPF and SIRF were determined, and the final displacement (mm) of the fracture region and angular deformity (degrees) were measured. Displacements were measured using the markers at two sites of the sacral fracture [upper margin of the sacral ala (Ala) and second sacral vertebra level (S2)] and one site of the pubic symphysis (PS), and angular deformity was measured at Ala and PS. RESULTS: In SPF and SIRF, the mean stiffnesses and deformations showed no statistically significant difference. Only the vertical displacement at Ala differed significantly between SPF and SIRF (p = 0. 045), and the fixing force of SPF was higher. There was no other significant difference in vertical and horizontal displacement. The mean angular deformities also showed no significant difference between the two methods. CONCLUSIONS: In biomechanics experiments, vertical resistance was stronger in SPF-treated than SIRF-treated bone, but stiffness and deformation, horizontal resistance, and angular deformity did not differ significantly.

"Within ring"-based sacroiliac rod fixation may overcome the weakness of spinopelvic fixation for unstable pelvic ring injuries: technical notes and clinical outcomes.

PURPOSE: Spinopelvic fixation and triangular osteosynthesis give firm internal fixation for unstable pelvic ring injuries (UPRI), but with sacrifice of mobility of the lumbar spine. Here, we describe the procedure and outcomes of a new approach, which we refer to as "within ring"-based sacroiliac rod fixation (SIRF). METHODS: The patient was placed in a prone position and longitudinal skin incisions were made at the medial margins of the bilateral posterior superior iliac spines (PSIS). After reduction of fracture, a pedicle screw was inserted into the first sacral vertebra on the injured side and iliac screws inserted through the bilateral PSIS were bridged using rods. RESULTS: SIRF was performed in 15 patients. The AO/OTA classification was 61-B2.3 in 1, C1.3 in 4, C2.3 in 7, C3.3 in 1, and H-type spinopelvic dissociation in two cases. The mean operative time was 179 (110-298) minutes, mean blood loss was 533 (100-2700) cc. One patient died during hospitalization and three patients stopped outpatient treatment. The other 11 patients achieved bone union without major loss of reduction in a mean post-operative follow-up period of 23.8 (4-50) months. The mean Majeed score at final follow-up was 86.7 (73-96) out of 96, excluding scoring sexual intercourse. CONCLUSIONS: "Within ring"-based SIRF not including the lumbar spine in the fixation range is a simple, safe, and low-invasive internal fixation method for UPRI.

The Baba classification focused on implant designs is useful in setting the therapeutic strategy for interprosthetic femoral fracture.

PURPOSE: The purpose of this study was to investigate the clinical outcomes of femoral fracture with implants on the proximal and distal sides to verify whether actual fracture morphologies follow the fracture types of Baba classification focusing on implant designs useful for periprosthetic femoral fracture. METHODS: Prosthesis was present in 85 with periprosthetic femoral fractures. Excluding 73 patients with fracture around the femoral stem or fracture of the TKA femoral component alone, 12 patients with 14 legs with both implants were investigated. All patients were radiographically assessed for implant stability according to the Baba classification. For clinical evaluation, intra- and postoperative complications, the operation time, and intra-operative blood loss were investigated. RESULTS: The Baba classification fracture type showed the implant as unstable and stable types in 3 and 11 legs, respectively. The consistency rate between the Baba classification-based judgment of plain radiograms acquired at the time of injury and actual surgical findings was 100%. As a result of treatment according to the Baba classification, bone union was achieved in all patients. There were no intra- or postoperative complications. CONCLUSIONS: Applying the Baba classification, implant stability could be sufficiently evaluated in not only periprosthetic femoral fractures following hip arthroplasty, but also interprosthetic femoral fractures, thereby verifying its usefulness in setting the treatment strategy.

In total hip arthroplasty via the direct anterior approach, a dual-mobility cup prevents dislocation as effectively in hip fracture as in osteoarthritis.

PURPOSE: The main purpose of this study was to compare the outcome of total hip arthroplasty (THA) via the direct anterior approach (DAA) using a dual-mobility cup (DMC) in patients with femoral neck fracture to those in patients undergoing elective THA for osteoarthritis. PATIENTS AND METHODS: We retrospectively investigated 40 hips with femoral neck fracture (group A), and 81 hips with osteoarthritis (group B). THA via the DAA using the DMC was performed in both groups. A primary/secondary outcome variable were the presence of dislocation/operative time, intra- and/or peri-operative complication, and mortality. RESULTS: Dislocation did not occur in either group. The complication rate was slightly higher in group A than in group B, but not statistically significant. CONCLUSION: THA with the DMC using the DAA was as effective for femoral neck facture as it was for elective THA in patients with osteoarthritis.

Long-term results of rotational acetabular osteotomy for osteonecrosis with collapse of the femoral head in young patients.

PURPOSE: The surgical treatment of osteonecrosis with collapse of the femoral head is still controversial. The purpose of this study was to investigate the clinical outcome of rotational acetabular osteotomy by Ninomiya and Tagawa for osteonecrosis of the femoral head in young patients. PATIENTS AND METHODS: Rotational acetabular osteotomy was performed in 202 consecutive patients between 1995 and 2003. Among them, rotational acetabular osteotomy with osteonecrosis of the femoral head was performed in 31 patients (42 hips). The mean age at the time of surgery was 31.2 years (range 16-45). The mean duration of follow-up was 16.1 years (range 13.1-21 years). RESULTS: The mean preoperative Japanese Orthopedic Association hip score of 56.8 points improved to a mean of 72.4 points at the final follow-up. The 10-year survival rate with conversion to total hip arthroplasty as an end-point was 91.9%, and the 15-year survival rate was 75.5%, the 20-year survival rate was 67.9%. The conversion to total hip arthroplasty was performed in nine hips. The average time to the conversion to total hip arthroplasty was 12.1 years. CONCLUSIONS: Even though the necrotized range is wide, if normal cartilage remains on the lateral side of the femoral head, it can be utilized for the weight-bearing region by laterally rotating the acetabulum. Since the outcome was favorable, we believe that this is a valuable treatment option for this disease.

Influence of the contralateral hip state after total hip arthroplasty on patient-reported outcomes measured with the Forgotten Joint Score-12.

PURPOSE: The purpose of this study was to examine the influence of the contralateral hip state on postoperative assessment using the Forgotten Joint Score-12 (FJS-12) in comparison with the McMaster Universities Osteoarthritis Index (WOMAC) and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). METHODS: One hundred and thirty-four hips underwent total hip arthroplasty (THA) between 2014 and 2015. Of these, the subjects were 106 hips with degenerative hip arthrosis as a primary disease for whom initial THA was performed on the affected side. The WOMAC and JHEQ were investigated before surgery and 1 month, 6 months, and 1 year after surgery. The FJS-12 was examined 1 month, 6 months, and 1 year after surgery. RESULTS: We divided the subjects into three groups based on the state of the contralateral hip, which was not surgically treated in this study: healthy (n = 43), THA (n = 31), and OA (n = 31) groups. One year after surgery, the mean FJS-12 scores in the healthy, THA, and OA groups were 69.1, 52.8, and 68.0 points, respectively. In the THA group, the score was significantly lower than in the healthy and OA group. There were no significant differences in WOMAC and JHEQ scores among the three groups. CONCLUSIONS: The FJS-12 score in the presence of an arthroplasty on the contralateral side was more markedly influenced by the contralateral hip state compared with that in the presence of contralateral painful OA. This result suggests that it is necessary to understand the characteristics of PROs and utilize them for post-THA assessment.

Importance of the spinopelvic factors on the pelvic inclination from standing to sitting before total hip arthroplasty.

PURPOSE: Dislocation after total hip arthroplasty (THA) is a major postoperative complication. Even if the cup is in the safe zone, dislocation caused by implant impingement may occur during postural changes. The aim of the present study was to investigate the spinopelvic factors that influence pelvic inclination changes from standing to sitting in patients with hip diseases who were candidates for THA. METHODS: 74 patients who underwent primary THA were included according to our criteria. The analysis of the sagittal balance of the spinopelvic complex was performed on standing and sitting lateral radiographs. Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis angle (LLA), thoracic kyphosis angle (TK), and sagittal vertical axis (SVA) were measured. The differences between the standing and sitting positions regarding the spinal and pelvic parameters were analyzed. Correlations between the variables of the spinopelvic parameters were examined using Spearman's rank correlation coefficient. RESULTS: The changes in SVA, TK, LLA, SS, PT, and PI from the standing to sitting positions, respectively, were -3.9 ± 48.2 mm, -0.1° ± 6.4°, 21.4° ± 17.7°, 22.2° ± 12.2°, -22.3° ± 13.2°, and 0.4° ± 6.9°. The lumbar lordosis was reduced and pelvic rotation was extended from the standing to the sitting position. The correlation coefficient between the change in the SS and that in the LLA was 0.72 (p < 0.0001). The correlation coefficient between the change in PT and that in the LLA was -0.68 (p < 0.0001). CONCLUSIONS: The change in pelvic inclination from standing to sitting is strongly related to the mobility of the lumbar spine in patients with hip diseases.