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.

A case series of prophylactic negative pressure wound therapy use with purse-string closure in stoma closure wounds in infants.

BACKGROUND: The study introduces the application of negative pressure wound therapy (NPWT) in pediatric stoma closure, emphasizing the importance of enhancing aesthetics and minimizing surgical site infections (SSI). CASE PRESENTATION: The case series involves four infants undergoing non-umbilical stoma closure with a combination of purse-string closure (PSC) and NPWT, focusing on aesthetic outcomes and infection prevention. NPWT was initiated immediately after surgery, and patients were monitored every 3-4 days. Notably, none of the four infants experienced SSI or other complications. The patients adequately tolerated NPWT, with no significant adverse events. Furthermore, Manchester Scar Scale (MSS) was 9 [7-10], and Patient and Observer Scar Assessment Scale (POSAS) (observer) was 12.5 [12-19], POSAS (patient) was 12.5 [11-16] (all median values [minimum-maximum]), indicating that excellent aesthetic outcomes were achieved. DISCUSSION: We emphasizes the significance of aesthetics in pediatric patients; in addition, our findings demonstrate that four infants who received NPWT combined with PSC achieved superior outcomes that did the most recent four infants who underwent PSC only at our institution. It also addresses the risk of SSI in stoma closure and discusses the pros and potential cons of using NPWT in pediatric cases, underlining the need for further research and the accumulation of additional reports. CONCLUSIONS: This is the inaugural report of prophylactic NPWT for pediatric stoma closure, emphasizing the effectiveness of combining PSC and NPWT for SSI prevention and improved aesthetics. The study calls for additional research and reports on NPWT in pediatric cases to further solidify its benefits in this patient population.

Recent advances in the direct anterior approach to total hip arthroplasty: a surgeon's perspective.

INTRODUCTION: The direct anterior approach (DAA) has its origins in the first and oldest approach for hip replacement in the literature, but at the same time it would not be fanciful to suggest its increasing popularity as the latest approach for hip replacement procedures, especially among younger surgeons. However, in a geographical context, the DAA is not considered the major approach in most countries. Moreover, the term DAA encompasses numerous variations in terms of technique. AREAS COVERED: In this narrative review, we describe our recent experience of advances in the DAA in terms of improved techniques and devices, along with some of its disadvantages. Also, we express our perspective on its future application. EXPERT OPINIONS: The DAA is established as one of exemplary approaches to THA. The use of fluoroscopy, the traction table, and appropriate soft tissue management has become essential in the DAA for a safe and trouble-free procedure with adequate patient comfort. With the combination of recent technologies such as robotics, three-dimensional preoperative planning, and artificial intelligence (AI)-based surgeon assist systems, we can look forward to the DAA being performed more efficiently in the future.

Quantitative evaluation of pediatric umbilical loop stomas: 2 decades of experience from a single institution.

PURPOSE: Since pediatric stomas are often temporary, their creation, management, and closure should be simple, with minimal complications and excellent cosmetic results. We began employing umbilical stomas in 2000. This study aimed to characterize the ingenuity and utility of umbilical stomas and provide a quantitative evaluation of their cosmetic outcomes. METHODS: We examined cases of stoma construction and closure surgery performed in our department from January 2000 to December 2022. The umbilical and non-umbilical stoma groups included 54 and 42 cases, respectively, and the findings for both groups were compared and analyzed. RESULTS: The two groups showed no significant differences in the incidence of complications. The Manchester Scar Scale score for the umbilical stoma group (8.42 ± 1.85) was significantly better than that for the non-umbilical stoma group (16.31 ± 2.96; P < 0.01). Likewise, in Patient and Observer Scar Assessment Scale assessments, the umbilical stoma group showed significantly better scores in both the observer scale (9.48 ± 2.50 vs. 21.78 ± 7.26; P < 0.01) and the patient scale (10.5 ± 1.39 vs. 22.40 ± 7.35; P < 0.01). CONCLUSIONS: Umbilical stomas are easy to manage and yield an inconspicuous closure incision with excellent cosmetic outcomes. Although patient selection is important, pediatric umbilical stomas are a valuable option that can be actively employed.

Patients With Shorter Stature Exhibit Minimal Hammering Sound Changes During Cementless Stem Insertion in Total Hip Arthroplasty.

Background: Listening to the change in the hammering sound is 1 of the elements used to assess the cementless stem stability. This study aimed to quantitatively investigate the change in the acoustic characteristics between the early and late phases of cementless stem insertion in total hip arthroplasty and to identify which patient characteristics contribute to the change in the hammering sound. Methods: The acoustic parameters of the hammering sounds in the early and late phases of cementless taper-wedged stem insertion for 51 hips in 45 patients who underwent total hip arthroplasty (mean age = 68 years, height = 1.56 m, weight = 55.0 kg) were analyzed. Parameters including patient's basic characteristics, radiographical femoral morphology, and canal fill ratio were assessed as potential contributors to the change in the hammering sound. Results: The low-frequency bands (0.5-1.0 kHz and 1.0-1.5 kHz) showed the largest changes during stem insertion and were therefore considered key bands for the analysis of sound alterations. Multivariate linear regression analysis showed that height (ß = 8.312, P = .013) and proximal canal fill ratio (ß = -3.8568, P = .038) were independently associated with the sound alterations. The decision tree analysis identified height (≥1.66 m or <1.66 m) as the best single discriminator for the sound alteration. Conclusions: Patients with smaller stature showed the least change in the hammering sound during stem insertion. Understanding the acoustic characteristics of hammering sound alteration during cementless stem insertion may aid in the achievement of optimal stem insertion.

Validation of a preoperative formula to estimate postoperative pelvic sagittal alignment and mobility before performing total hip arthroplasty for patients with hip osteoarthritis.

BACKGROUND: Although it is important to consider pelvic alignment and mobility in the standing and sitting positions before THA, it is not known how to preoperatively predict individual postoperative pelvic alignment and mobility. The purpose of this study was to investigate the pelvic alignment and mobility before and after THA, and to develop a predictive formula using preoperative factors to calculate postoperative sagittal alignment and mobility. METHODS: One hundred seventy patients were assessed. The 170 patients were randomly divided into a prediction model analysis group (n = 85) and an external validation group (n = 85). In the prediction model analysis group, preoperative spinopelvic parameters were used to develop the predictive formulas to predict the postoperative sacral slope (SS) in standing and sitting positions and ΔSS. These were applied to the external validation group and assessed. RESULTS: R2 in multiple linear regression models for postoperative SS in standing, SS in sitting and ΔSS were 0.810, 0.672, and 0.423, respectively. The values of predicted and postoperative parameters were very close with no significant difference: SS in standing (33.87 vs. 34.23, P = 0.834), SS in sitting (18.86 vs. 19.51, P = 0.228), and ΔSS (15.38 vs. 14.72, P = 0.619). CONCLUSION: The present study showed that the pelvic alignment and mobility after THA can be predicted using preoperative factors. Although a model with higher accuracy is needed, it is important to use a predictive formula to estimate the postoperative condition before performing THA.

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.

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.

Acetabular morphological variation in Asian patients with femoral neck fracture: A three-dimensional CT-based study.

AIMS: The acetabular morphology varies greatly among individuals, and hypoplasia is more common in Asia than in Europe. Dislocation after bipolar hip arthroplasty (BHA) for femoral neck fracture occurs at a constant rate, and is affected by the acetabular morphology. This study aimed to clarify individual differences in the acetabula of Asian patients with displaced femoral neck fractures. PATIENTS AND METHODS: Fifty patients with displaced femoral neck fractures were assessed (50 fractured hips, 50 non-fractured hips). On CT corrected by the anterior pelvic plane, the 100 hips were assessed regarding acetabular coverage (six parameters), acetabular depth (two parameters), and acetabular opening angle (four parameters). Additional parameters related to the fracture and sex were examined. The percentile of each parameter was shown for all hips. RESULTS: There was no patient with hip dysplasia defined as superior acetabular sector angle (SASA) less than 110° Compared with men, women had a significantly smaller anterior acetabular sector angle (AASA) (p = 0.016), and significantly larger acetabular inclination angle (p = 0.006) and acetabular index angle (p = 0.034). In the group with a normal SASA, seven hips (7.3%) had an anterior wall defect (AASA<50°) and five hips (5.2%) had a posterior wall defect (posterior acetabular sector angle<90°). CONCLUSION: Older adults with femoral neck fractures can have anterior wall and posterior wall defects, even if their SASA is normal. Hidden acetabular dysplasia may be related to post-BHA dislocation. So, our results suggest that is important to accurately evaluate the acetabulum of patients with femoral neck fracture before surgery.

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.

Damage control surgery for grade IV blunt hepatic injury with multiple organ damage in a child: a case report.

BACKGROUND: Intra-abdominal hemorrhage caused by blunt hepatic injury is a major cause of morbidity and mortality in patients with abdominal trauma. Some of these patients require laparotomy, and rapid decision-making and life-saving surgery are essential. Damage control (DC) surgery is useful for treating children in critical situations. We performed this technique to treat an 8-year-old boy with grade IV blunt hepatic injury and multiple organ damage. This is the first report of the use of the ABTHERA Open Abdomen Negative Pressure Therapy System (KCI, now part of 3 M Company, San Antonio, TX, USA) for DC surgery to rescue a patient without neurological sequelae. CASE PRESENTATION: An 8-year-old boy was brought to the emergency department of our hospital after being run over by a motor vehicle. He had grade IV blunt hepatic injury, thyroid injury, and bilateral hemopneumothorax. Although he was hemodynamically stable, the patient's altered level of consciousness, the presence of a sign of peritoneal irritation, and suspicion of intestinal injury led us to perform exploratory laparotomy. As part of a DC strategy, we performed gauze packing to control hemorrhage from the liver and covered the abdomen with an ABTHERA Open Abdomen Negative Pressure Therapy System to improve the patient's general condition. Eighteen days after admission, the patient was diagnosed with a biliary fistula, which improved with percutaneous and external drainage. He had no neurological sequelae and was discharged 102 days after injury. CONCLUSION: The DC strategy was effective in children with severe blunt hepatic injury. We opted to perform DC surgery because children have less hemodynamic reserve than adults, and we believe that using this strategy before the appearance of trauma triad of death could save lives and improve outcomes. During conservative management, it is important to adopt a multistage, flexible approach to achieve a good outcome.

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.

Valgus osteotomy for atypical interprosthetic femoral fracture with lateral bowing of the femur.

INTRODUCTION: In recent years, it has been reported that periprosthetic femoral fractures in the form of atypical femoral fractures (AFFs) are found occasionally as difficult-to-treat conditions. To date, there have been no reports of interprosthetic femoral fractures (IPFFs) having the form of AFFs. We report a case of an atypical IPFF with breakage of the plate due to abnormal femoral alignment. CASE REPORT: A 70-year-old woman was admitted. She underwent left knee replacement and left hemi-arthroplasty at ages 61 and 60. And she had been taking bisphosphonate for 5 years. A plain X-ray revealed IPFF. The fracture was a complete transverse fracture with circumscribed thickening of the lateral cortical bone ("beak sign") at the fracture site. She underwent surgery. A reversed condylar locking compression plate (LCP) was used for internal fixation. Subsequently, she could walk without particular pain. Five months after the operation, she heard the snap of a bone breaking, and had difficulty walking. Plain X-ray revealed a re-fracture of the fracture site and breakage of the plate at the same high position. She underwent re-operation. A valgus osteotomy was performed at an angle of 15°. A reversed condylar LCP was used on the lateral side of the femur. A bone grafting was performed focusing on the fracture site. In addition, a short-LCP was fixed anteriorly to the femur. The bone union 1 year and 6 months postoperatively. She could walk, with no impairment being noted regarding ADL. CONCLUSIONS: We performed osteosynthesis for an IPFF having the characteristics of AFF, but the patient suffered breakage of the plate and re-fracture. Bone union was achieved as a result of re-operation that consisted of valgus osteotomy of the fracture site in combination with autologous bone grafting and double orthogonal plating.

Does total hip arthroplasty via the direct anterior approach using dual mobility increase leg length discrepancy compared with single mobility?

BACKGROUND: Total hip arthroplasty (THA) via the direct anterior approach (DAA) using dual mobility cup (DMC) is considered to effectively prevent postoperative dislocation. However, the dislocation and reduction procedure using a trial implant during the surgery is difficult because of high soft tissue tension. Thereby, leg length discrepancy (LLD) is difficult to assess when using DM via the DAA. PURPOSE: To compare the LLD between cases using conventional SM and those using DMC in THA via the DAA with fluoroscopy. PATIENTS AND METHODS: We retrospectively investigated 34 hips treated with DMC (DMC-DAA group) and 31 hips treated with SM (SM-DAA group). The LLD was defined as the difference in the distance from the teardrop to the medial-most point of the lesser trochanter between the operative and nonoperative sides at immediate postoperative X-ray. RESULTS: The mean LLD in the DMC-DAA group and SM-DAA group was 0.68 ± 7.7 mm and 0.80 ± 5.5, respectively, with no significant difference. The absolute value of the LLD in the DMC-DAA group and SM-DAA group was 6.3 ± 4.4 mm and 5.9 ± 5.5, respectively, with no significant difference. CONCLUSION: Despite the difficulty in assessment of the LLD during THA via the DAA using DMC, this technique does not increase the LLD compared with the use of SM. LEVEL OF EVIDENCE: III, matched case-control study.

Horror of three synergistic factors in THA: high mechanical stress, dissimilar metals, low elasticity stem: a case report.

BACKGROUND: A large-diameter femoral head is effective in preventing dislocation after total hip arthroplasty. However, although rare, catastrophic stem tribocorrosion may occur at the head-stem junction. CASE PRESENTATION: A 70-year-old woman underwent revision surgery 7.5 years after total hip arthroplasty because of catastrophic stem corrosion with dissociation of the metal head (cobalt/chromium) and stem (TiMo12Zr6Fe2). Abnormal levels of cobalt were found in the intra-articular fluid, capsule, hip muscle, and blood. Revision surgery was performed via the direct anterior approach. The well-fixed femoral stem was explanted, and a cemented stainless stem with stainless head was implanted. Three months after the revision surgery, the cobalt concentration in the blood had decreased to normal. CONCLUSIONS: Stem dissociation in the present case might have been caused by synergistic combination of a 36-mm-diameter femoral head and long neck length offset with high frictional torque, a cobalt-chromium head with a high risk of galvanic corrosion, and a TMZF (TiMo12Zr6Fe2) alloy stem with a low Young's modulus of elasticity. The combination of these factors must be avoided.

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.

[Residual Property of SI-613, a Novel Drug for Osteoarthritis, in Knee Joint].

Osteoarthritis is the most common joint disorder worldwide and one of the leading causes of disability in the elderly. We have reported that the novel sodium hyaluronate derivative chemically linked with diclofenac (DF), diclofenac etalhyaluronate (SI-613), exerted a potent and long-lasting analgesic effect in experimental arthritis models. In this study, we evaluated the properties of residual SI-613 in the knee joint after an intra-articular (IA) administration. After IA administration of fluorescent labeled SI-613 (FA-SI-613) or fluorescent labeled hyaluronic acid (FA-HA) to rabbits, fluorescence intensities in the synovial membrane and cartilage were higher in the FA-SI-613 group until 7 d after administration than in the FA-HA group. After IA administration of radiolabeled SI-613 (14C-SI-613) to rabbits, the radioactivity remained in the joint cavity and the joint tissues such as synovial membrane and cartilage until 84 d after administration. This residual radioactivity was identified mainly as HA linked with DF, since 14C-SI-613 was labeled at the benzene ring of DF and since more DF-linked HA oligomer was detected on metabolite analysis than free DF in the synovial membrane and synovial lavage fluid up to 28 d after administration. These results suggested that intra-articularly administered SI-613 remained for a longer time in the joint as HA linked with DF than when HA was administered. Therefore, SI-613 was considered to prolong the pharmacological effects of both HA and DF by remaining in the joint as HA linked with DF.

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.

Does the Canal Fill Ratio and Femoral Morphology of Asian Females Influence Early Radiographic Outcomes of Total Hip Arthroplasty With an Uncemented Proximally Coated, Tapered-Wedge Stem?

BACKGROUND: Noncement femoral fixation in total hip arthroplasty (THA) has been gaining popularity. However, owing to the numerous varieties of uncemented stems and differing types of femoral stem morphology, it is unclear whether the clinical outcomes of all uncemented stems are equal. The aim of this study was to investigate the relationships between canal fill ratio and femoral morphology and early radiologic outcomes in Japanese patients who underwent THA with an uncemented proximally hydroxyapatite-coated, tapered-wedge stem. METHODS: We retrospectively reviewed 103 patients who had undergone THA using a single proximally coated tapered-wedge stem. The relationships between canal fill ratio and femoral morphology and early radiologic outcomes after THA with those stem were investigated. RESULTS: Eighty-one hips were analyzed after inclusion and exclusion criteria were applied. Failed osteointegration proximally was observed in 4 hips (4.9%). Canal flare index was significantly greater in hips with failed osteointegration than in those with successful osteointegration (P = .009). Distal hypertrophy was observed in 14 hips (17.3%). Proximal-distal matching ratio was significantly lower in hips with distal hypertrophy than in those without (P = .01). Canal fill ratio at 2 cm above the lesser trochanter was smaller in hips with failed osteointegration and distal hypertrophy than in those without (P = .02). CONCLUSION: Suboptimal radiologic changes were seen with greater distal fill with smaller proximal fill and with a narrow femoral canal. It is important to select the stem that can achieve the original concept of intended primary and secondary fixation areas.