Should the diameter of the proximal femoral nail be large enough to fill the canal in the treatment of intertrochanteric femoral fracture in patients over fifty?

PURPOSE: Many studies have been conducted to evaluate the effects of nail shape, design, or length on the treatment of intertrochanteric fractures. However, the clinical implications of the nail diameter remain unclear. METHODS: This study was conducted with 191 patients aged ≥ 50 years with unilateral intertrochanteric fractures treated with the same type of short cephalomedullary nail and followed for at least one year. We recorded the reduction type, tip-apex distance, cortical contact of the nail, and nail/canal diameter ratio (NCR) just distal to the locking screw. The effects of nail diameter on the clinical results were evaluated. RESULTS: The average NCR was 68.7. The average union time was 4.78 months. Delayed union or nonunion was seen in 17 patients. Eight patients underwent additional surgery. The mean change in the modified Koval activity score was -0.84. The NCR did not significantly affect the clinical results. Comparisons of cases with NCRs above and below the average and the average - 1 standard deviation revealed no significant difference. The clinical outcome was not related to any variable associated with the nail diameter. CONCLUSION: With this specific proximal femoral nail, a small diameter relative to that of the femoral canal had no adverse effect on the union of osteoporotic intertrochanteric fractures, even in patients with unstable fractures and those who had unsatisfactory reductions.

Favorable mid-to-long-term results of impaction bone grafting using a fresh frozen allograft bone with cemented stem for the treatment of Paprosky IV femoral bone defects.

BACKGROUND: Femoral revision surgery in patients with substantial bone loss is challenging. Impaction bone grafting using a cemented stem can be a good solution for reconstruction of the femur with poor bone stock and extensive bone loss. This study aimed to evaluate the mid-to-long-term clinical and radiographic results of impaction bone grafting using a cemented stem for Paprosky IV femoral bone defects. METHODS: Thirteen patients (13 hips) who underwent revision total hip arthroplasty with impaction bone grafting using a cemented stem and were followed up for at least 5 years were enrolled in this study. In all patients, a sufficient amount of fresh frozen bone of good quality was used. When cortical segmental defects were present, peripheral reinforcement with metal mesh and strut allograft was performed. The average follow-up duration was 11.1 (range, 5.3-15.1) years. The clinical and radiographic outcomes were reviewed at the final follow-up. RESULTS: The average Harris hip score was 82.5 (range, 79-94), and the average University of California, Los Angeles activity score was 5.6 (range, 4-8) at the final follow-up. Radiographic assessment revealed an average femoral component subsidence level of 0.67 (range, 0.05-2.81) mm. There were no complications, except one case (7.6%) of periprosthetic fracture. CONCLUSIONS: Impaction bone grafting using a cemented stem yielded excellent mid-to-long-term outcomes. It is a reliable technique for Paprosky IV femoral bone defects, and even when severe femoral cortical bone defects are present, long-term stability can be obtained using a metal mesh and/or strut allograft.

Long-Term Results of Periacetabular Rotational Osteotomy Concomitantly With Arthroscopy in Adult Acetabular Dysplasia.

BACKGROUND: Although the long-term results of periacetabular osteotomy in acetabular dysplasia have been well documented, there is paucity in reports on the long-term outcomes of periacetabular osteotomy with simultaneous hip arthroscopy. This study aimed to assess the cumulative 10-year outcomes of periacetabular rotational osteotomy with concomitant hip arthroscopy. METHODS: Through an arthroscopic procedure, the status of the labrum was assessed, and torn labrum was debrided. Evaluations on survival from conversion to total hip arthroplasty and success in radiographic and clinical long-term results were completed in 39 hips (36 patients). Acetabular parameters (center-edge angle, Sharp angle, acetabular-head index, and head lateralization index), Tönnis grades on radiograph, Harris Hip Score, and range of motion of the hip were evaluated. Survivorship analyses were evaluated with the Kaplan-Meier method. RESULTS: Thirty-eight hips (97.4%, 95% confidence interval 0.832-0.996) were preserved for 12.8 ± 1.7 years on average, and only 1 hip was converted to total hip arthroplasty at 7.8 years. All the acetabular parameters were improved (P < .001). Twenty-eight hips (71.8%) showed unchanged or improved Tönnis grades at the latest follow-up. The average Harris Hip Score was significantly better than the preoperative value (P < .001), and range of motion was not significantly different until the latest follow-up. CONCLUSION: Sufficient acetabular reorientation, such as periacetabular rotational osteotomy, with concomitant arthroscopic debridement showed successful long-term outcomes for acetabular dysplasia in adults.

Age and sex-related distribution of alpha angles and the prevalence of the cam morphology of the hip in Asians do not differ from those of other ethnicities.

PURPOSE: This study was performed to evaluate the effects of age on the alpha angle and the incidence of asymptomatic cam morphology. METHODS: The radiographs of asymptomatic individuals between ages 8 and 22 were retrospectively collected. A total of 1417 individuals were included and grouped according to age: 8-12 (Group A), 13-18 (Group B), and 19-22 (Group C) years. Radiographic measurements of the alpha angles of the right hip were obtained from anteroposterior (AP) and frog-leg lateral (FL) radiographs. The correlations among alpha angles, the presence of cam morphology, and age were determined. RESULTS: The mean alpha angles of the three groups were statistically different (p < 0.001, each). The alpha angles on both radiographs were positively correlated with age. Intra-group analysis revealed that this correlation was only evident on the FL images of males in Group B. The presence of a radiographic cam morphology also positively correlated with age (p < 0.001 in both AP and FL images). The cam morphology on AP radiographs was 0 in Group A, 17(3.0%) in Group B, and 21(4.8%) in Group C; that on FL radiographs was 2(0.3%) in Group A, 45(7.9%) in Group B, and 103(23.6%) in Group C. Intra-group analysis revealed that the correlation was only significant in males in Group B. CONCLUSIONS: Higher alpha angles and the presence of cam morphology were positively correlated with age, particularly in males at or before the time of skeletal maturation. The prevalence of cam morphology did not differ from those in other ethnicities. LEVEL OF EVIDENCE: IV.

Novel Antibiotic-Loaded Cement Femoral Head Spacer for the Treatment of Advanced Pyogenic Arthritis in Adult Hip.

BACKGROUND: The aim of this study is to present a treatment for end-stage pyogenic arthritis of the hip using a novel cement spacer. This spacer caused less damage to the proximal femoral bone and made the conversion to total hip arthroplasty (THA) more convenient while maintaining the advantages of current cement spacers loaded with antibiotics. METHODS: We retrospectively reviewed 10 consecutive cases of hip pyogenic arthritis with joint destruction. These cases occurred from September 2009 to June 2015. In these cases, we used an antibiotic-loaded, cement spacer that was formed in the shape of the femoral head. This spacer rested on multiple screws that were inserted in the remaining neck of the femur. Once the infection subsided, a conversion to THA was performed in all cases. Evaluation included clinical and radiologic outcomes and the development of complications. RESULTS: The mean interval between spacer insertion and conversion to THA was 101.6 days (range, 59-187 days). The mean follow-up period from initial spacer insertion was 44.9 months (range, 15-95 months). All cases underwent noncemented THA following the resolution of the initial infection. The mean Harris Hip Scores at initial visit, before conversion to THA, and on final follow-up were 58.8, 71.0, and 92.5, respectively. No case had any spacer-related complications, recurrence of infection, or dislocation. CONCLUSION: The treatment of advanced pyogenic arthritis with this novel femoral head spacer technique significantly reduced pain, preserved proximal femoral bone and soft tissue tension, controlled infection, improved function, and allowed for easier conversion to THA.

High incidence of early subtrochanteric lateral cortical atrophy after hip arthroplasty using bone-conserving short stem.

PURPOSE: Load transfer to the bone is believed to be more physiological around the short stem in total hip arthroplasty (THA). However, we found unusual bony remodeling around the shortened tapered stem. This study was performed to investigate the extent and frequency of this phenomenon and to find the possible risk factors of it. METHODS: Among 121 consecutive THA using the same short stem, 80 THAs were enrolled. Radiographic measurements were made using anteroposterior (AP) radiographs taken immediately and at two years after surgery. The thickness of the lateral cortex at the level of the distal end of the coated surface and at 10, 20, 30, and 40 mm proximal to it were measured. RESULTS: Significant atrophy was noted in all regions (P < 0.001 each). In 46 cases, this presented as an intra-cortical osteolytic line (IOL). Sixty-one cases showed either an IOL or atrophy >10%. The risk of a mean reduction >20% was related to an increased operating time (odds ratio [OR] = 0.981; 0.966 < 95% confidence interval [CI] < 0.996) and lower body mass index (BMI) (OR = 1.216; 1.043 < 95% CI < 1.417). Periprosthetic fracture through the lateral cortex occurred in one case. CONCLUSION: Even with THA using a shortened stem, high incidence of proximal stress shielding was noted in the form of lateral cortical atrophy, especially for the patient with low BMI.

Asymmetric epiphyseal closure of the femoral head as a potential cause of the primary cam lesion: a case report.

Cam-type femoroacetabular impingement is a pathologic condition caused by repetitive impact of the abnormal femur on a normal acetabular rim, resulting in damage to the articular cartilage. Excluding cases with known underlying diseases, the development of primary cam deformity is not well understood. Here, we describe a patient with cam-type femoroacetabular impingement exhibiting delayed epiphyseal closure at the site of the cam lesion. The authors believe that this may represent a cause of primary cam deformity, and hereby report the case with review of the literature.

Does osteoporosis increase early subsidence of cementless double-tapered femoral stem in hip arthroplasty?

Among 320 hip arthroplasties performed between January 2007 and March 2008, patients younger than 50 years old and patients older than 70 with a T-score at the proximal femur less than -2.5 made up the control and study group, respectively. There were 40 patients in each group. We measured stem subsidence, both digital and manual methods. Measurements were made from radiographs taken serially from 2 weeks to 1 year after surgery. The amount of mean subsidence for each group was not different, and all stems showed stable fixation in the final radiographs. Our study suggests that even in osteoporotic proximal femurs, press-fit fixation of double-tapered stems for hip arthroplasty can be safe and effective without excessive early subsidence.

Hip Resurfacing Arthroplasty after Failure of Tantalum Rod Insertion in Patients with Osteonecrosis of the Femoral Head.

Purpose: The purpose of this study was to examine the clinical outcomes and efficacy of hip resurfacing arthroplasty (HRA) in patients with osteonecrosis of the femoral head after the failure of porous tantalum rod insertion without rod removal. Materials and Methods: Conversion to hip resurfacing arthroplasty was performed in 10 patients (11 hips) with a mean period of 14.9 months after the primary surgery. The mean follow-up period was 73.7 months. Analysis of pre and postoperative range of motion (ROM), University of California at Los Angeles (UCLA) activity score, modified Harris hip score, and visual analog scale (VAS) pain score was performed. Radiographic analysis of component loosening and osteolysis was performed. Results: The postoperative ROM showed significant improvement (P<0.05), excluding flexion contracture. The modified Harris hip score showed improvement from 65.82 to 96.18, the UCLA score showed improvement from 4.18 to 8.00, and the VAS pain score was reduced from 6.09 to 1.80. All scores showed statistically significant improvement (P<0.05). No component loosening or osteolysis was detected by radiographic analysis. Conclusion: Satisfactory results were obtained from conversion hip resurfacing arthroplasty after failure of porous tantalum rod insertion without rod removal. The findings of this study demonstrate the advantages of HRA, including no risk of trochanteric fracture and no bone loss around the tantalum rod. In addition, the remaining porous tantalum rod provided mechanical support, which reduced the potential risk of femoral neck fracture or loosening. This technique can be regarded as a favorable treatment option.

Patterns of labral tears and cartilage injury are different in femoroacetabular impingement and dysplasia.

The aim of this study was to assess injury patterns and risk factors of the acetabular labrum and associated cartilage in patients with femoroacetabular impingement (FAI) versus dysplasia. We retrospectively reviewed 137 patients diagnosed with labral tears and FAI or dysplasia (74 or 63 cases, respectively) through an arthroscopic procedure. Labral and concomitant cartilage injuries were evaluated. Demographics and radiological variables [lateral center-edge angle (LCEA), anterior center-edge angle, acetabular index (AI), acetabular version and alpha angle] were evaluated as risk factors for labral and cartilage injuries. Detachment of acetabular cartilage with intact labro-cartilaginous junction was the most common in dysplasia, whereas cartilage delamination from the labro-cartilaginous junction was more common in FAI (P < 0.001). A higher body mass index was significantly associated with delamination injury in FAI (odds ratio 1.226; 95% CI 1.043-1.441; P = 0.013). A significant correlation was evident between detachment injury and a larger AI in dysplasia (odds ratio 1.127; 95% CI 1.000-1.270; P = 0.049). In addition, symptom duration was positively correlated with the extent of labral tearing in FAI (P = 0.013), whereas the smaller LCEA was correlated with the larger extent of labral tearing in dysplasia (P = 0.044). FAI and dysplasia patients exhibited different labral and cartilage injury patterns. Increased body mass index was correlated with delamination injury in FAI, whereas an increased AI was associated with detachment injury in dysplasia. Greater tearing was associated with a longer symptom duration in FAI, and a decreased LCEA was a risk factor for the extent of tearing in dysplasia. Level of evidence Level III. Case-control study.

Significant associations of PAI-1 genetic polymorphisms with osteonecrosis of the femoral head.

BACKGROUND: The pathogenesis of osteonecrosis of the femoral head (ONFH) has been implicated in hypofibrinolysis and blood supply interruption. Previous studies have demonstrated that decreased fibrinolytic activity due to elevated plasminogen activator inhibitor-1 (PAI-1) levels correlates with ONFH pathogenesis. The -675 4G/5G single nucleotide polymorphism (SNP rs1799889) in the PAI-1 gene promoter is associated with PAI-1 plasma level. We investigated whether rs1799889 and two other SNPs of the PAI-1 gene (rs2227631, -844 G/A in the promoter; rs11178, +10700 C/T in the 3'UTR) are associated with increased ONFH risk. METHODS: Three SNPs in PAI-1 were genotyped in 206 ONFH patients and 251 control subjects, using direct sequencing and a TaqMan® 5' allelic discrimination assay. We performed association analysis for genotyped SNPs and haplotypes with ONFH. RESULTS: The 4G allele of rs1799889, A allele of rs2227631, and C allele of rs11178 were significantly associated with increased ONFH risk (p = 0.03, p = 0.003, and p = 0.002, respectively). When we divided the population according to gender, an association between the three SNPs and increased risk of ONFH was found only in men. In another subgroup analysis based on the etiology of ONFH, rs2227631 (A allele) and rs11178 (C allele) in the idiopathic subgroup (p = 0.007 and p = 0.021) and rs1799889 (4G allele) and rs11178 (C allele) in the alcohol-induced subgroup (p = 0.042 and p = 0.015) were associated with increased risk of ONFH. In addition, a certain haplotype (A-4G-C) of PAI-1 was also significantly associated with ONFH (p < 0.001). CONCLUSION: Our findings demonstrated that three SNPs (rs1799889, rs2227631, and rs11178) of the PAI-1 gene were associated with ONFH risk. This study also suggests that PAI-1 SNPs may play an important role in ONFH.

Role of total hip arthroplasty and resurfacing in Legg-Calvé-Perthes disease.

Hip replacement arthroplasty is a very reliable and effective therapeutic modality for patients with end-stage degenerative coxarthrosis secondary to Legg-Calvé-Perthes disease (LCPD). Long-term results of the conventional total hip arthroplasty for patients with LCPD have been reported to be satisfactory similar to those for patients with primary arthritis. For selective patients, resurfacing arthroplasty can be performed successfully. We described special aspects of patients with LCPD in conventional total hip arthroplasty and resurfacing arthroplasty.

Causes and patterns of aborting a robot-assisted arthroplasty.

For a successful robot-assisted arthroplasty, every step should be executed harmoniously. However, when we encounter serious obstacles during surgery, it is sometimes better to abort the procedure in a timely manner. This study investigated the possible causes and patterns of aborted robot-assisted arthroplasties. Of 100 consecutively planned robot-assisted arthroplasties, 22 cases were aborted. Most involved total knee arthroplasty (21/22 cases). We classified the causes according to the stage at which they occurred and the type of error. Abortions after starting the milling procedure and abortions due to an interactive factor were the most common. We believe that this study can guide surgeons to effective decision making during robot-assisted arthroplasty.

A Novel Surgical Method for Treating Symptomatic Incomplete Atypical Femoral Fracture using Percutaneous Elastic Intramedullary Nailing.

PURPOSE: To introduce the principles and procedure of percutaneous elastic intramedullary nailing (PEIN) as a treatment for symptomatic incomplete atypical femoral fracture (SIAFF). METHODS: From October 2014 to April 2019, 6 cases of SIAFF were treated with PEIN. Two pre-bent 4-mm stainless-steel nails were used to apply compressive force to the fracture site. The antegrade method was used for proximal fractures and the retrograde method for middle and distal femoral fractures. The femoral bowing angle in the coronal and sagittal planes, and the time required for callus formation and union, were evaluated on plain radiographs in both planes. Thigh pain, tenderness, and complications were also assessed. RESULTS: The mean operating time was 65.00 ± 22.64 min. No case progressed to complete atypical fracture. In one case, fracture occurred around the point of nail entry after the patient fell from a chair on postoperative day 7. The incomplete fracture lines were united in 5 cases, after excluding one case with a complication. The time taken to confirm endocortical callus formation, fracture line disappearance, and clinical union was 2.11 ± 0.53, 6.45 ± 4.10, and 6.45 ± 3.65 months, respectively. CONCLUSIONS: PEIN is a quick, simple but effective treatment for SIAFF that considers the fracture mechanism and is applicable to cases with severe femoral bowing. LEVEL OF EVIDENCE: Level IV, case series.

Deep vein thrombosis after total hip arthroplasty in Korean patients and D-dimer as a screening tool.

INTRODUCTION: This prospective study was designed to confirm risk factors and to assess the incidence of deep vein thrombosis after total hip and surface replacement arthroplasty in Korean patients not receiving anticoagulation prophylaxis and to determine efficacy of plasma D-dimer levels as a screening test. MATERIALS AND METHODS: From May 2003 to August 2004, 221 consecutive patients undergoing unilateral total hip arthroplasty and hip resurfacing were evaluated. All patients underwent ultrasonography preoperatively and venography and/or ultrasonography on postoperative day 7. Plasma D-dimer levels were estimated by latex immuno-assay preoperatively and on days 3 and 7 postoperatively. RESULTS: Of the 221 patients in our cohort, 23 developed deep vein thrombosis (10.4%). Age (r = 0.245, P < 0.001) and gender (r = 0.155, P = 0.021) significantly correlated with deep vein thrombosis. Rise in incidence paralleled increase in age (X(2) = 32.860, P < 0.001). D-dimer levels on postoperative days 3 (gamma = 0.364, P < 0.001) and 7 (gamma = 0.470, P < 0.001) were significantly correlated to the development of DVT. CONCLUSION: While incidence of deep vein thrombosis in Korean population after THA was lower than that in the West; it increased with age, and in female gender. Significant correlation was found between D-dimer levels and the development of deep vein thrombosis.

Critical differences between subtrochanteric and diaphyseal atypical femoral fractures: analyses of 51 cases at a single institution in Korean population.

There still remains controversy on the pathomechanism of atypical femoral fracture (AFF). The angle of lateral bowing and bone mineral density showed significant differences between subtrochanteric and diaphyseal atypical fracture groups. In addition to the use of bisphosphonate, mechanical factors might play important roles in the occurrence of AFFs. INTRODUCTION: Although AFF could be divided into subtrochanteric and diaphyseal fracture according to the location of fractures, there is a lack of evidence regarding differences between two fractures and etiology of the occurrence. The aim of study is to determine differences between atypical subtrochanteric and diaphyseal fracture in Korean population. METHODS: Between February 2010 and March 2015, 51 AFFs in 40 patients were included in this study. Their medical records were retrospectively reviewed. The AFF patients satisfied all the diagnostic criteria of the 2014 revised edition of the ASMBR. To analyze the differences according to the location of fracture, the AFFs were divided into subtrochanteric (n = 16) and diaphyseal (n = 35) fracture groups. The following factors were compared between two groups: patients' demographics, underlying diseases, laboratory findings (serum-25(OH) VitD3, osteocalcin, c-telopeptide, ALP, Ca, and P), bone mineral density (BMD), duration of bisphosphonate (BP) usage, and lateral bowing of the femur at time of the fracture. RESULTS: All AFFs happened in female patients (mean age, 73.8 years) who have received bisphosphonate treatments except three patients. The mean duration of bisphosphonate usage was 95.3 months. Between the two groups, demographic data (age, height, weight, and BMI), underlying diseases, laboratory findings, hip BMD, and duration of BP treatment were comparable to each other (p > 0.05). However, the subtrochanteric fracture group showed higher FNSBA (femoral neck shaft bowing angle, p < 0.001) and spine BMD (p = 0.014) compared to the diaphyseal fracture group. CONCLUSIONS: Angle of lateral bowing (FNSBA) and spine BMD showed significant differences between subtrochanteric and diaphyseal atypical fracture groups. According to our results, femoral bowing and spine BMD may play important roles in the AFF locations.

Effect of ligamentum teres tear on the development of joint instability and articular cartilage damage: an in vivo rabbit study.

The contribution of the ligamentum teres to the stabilization of the hip joint and the clinical influence of a compromised ligamentum teres are not well known. This study aimed to investigate joint stability and cartilage damage in a rabbit model by surgically inducing a complete ligamentum teres tear. Twenty adult New Zealand rabbits were used in this study. Rabbits were divided into complete ligamentum teres tear with capsulotomy (n = 9, group I) and capsulotomy only (n = 10, group II) groups. Unilateral surgery was performed on the left hip. Joint instability was assessed by measuring the preoperative and postoperative acetabulofemoral (A-F) distances. Rabbits were euthanized to assess cartilage damage at 24 weeks postoperatively. The median postoperative A-F distance of the operated side in group I [0.68 cm (0.37-1.04 cm)] was larger than that in group II [0.50 cm (0.30-0.65 cm)] (p = 0.041). The median postoperative A-F distance was larger in the operated side [0.68 cm (0.37-1.04 cm)] compared to the nonoperated side [0.45 cm (0.30-0.75 cm)] in group I; it also was larger in the operated side [0.50 cm (0.30-0.65 cm)] compared to the nonoperated side [0.44 cm (0.32-0.67 cm)] in group II, but only group I showed a significant difference (p = 0.016 and 0.395, respectively). Articular cartilage damage was detected at the apex of the femoral head in two rabbits (22.2%) in group I only. Rabbits with a complete ligamentum teres tear showed significant instability at the hip joint and articular cartilage damage in our rabbit model, supporting the potential clinical importance of ligamentum teres as a hip joint stabilizer.

[Changes of the bone mineral density of proximal femur after hip resurfacing arthroplasty].

OBJECTIVE: To evaluate the changes of periprosthetic bone mineral density in femur after hip resurfacing arthroplasty. METHODS: From July 2002 to June 2005, a comparative study was carried out on 52 hips in 52 patients. Twenty-six patients (26 hips) who underwent Birmingham hip resurfacing arthroplasty (group BHR), and 26 patients (26 hips) who performed cementless total hip arthroplasty with Versys System stem (group THA). The periprosthetic bone mineral density of the femur was measured through dual energy X-ray absorptiometry of the Gruen zones at pre-operation, post-operation 3, 6, 12 and 24 months in patients from both group BHR and group THA. The bone mineral density of femoral neck in group BHR was measured too. Changes of bone mineral density ratio in proximal femur between pre-operation and post-operation were compared and analyzed. RESULTS: The mean ratio of bone mineral density of the proximal femur in group BHR reduced by 5.8%, 4.9%, 2.6% and 0.4%, in group THA reduced by 7.0%, 10.6%, 1.0% and 4.1% at 3, 6, 12 and 24 months respectively. In group BHR, the mean ratio of bone mineral density in range of interest 1 decreased to 89.7% at 6 months and increased to 103.8% at 24 months, in range of interest 7 decreased to 95.1% at 6 months and increased to 103.7% at 24 months. In group THA, the mean ratio of bone mineral density in range of interest 1 decreased to 90.8% at 6 months, 94.4% at 24 months and in range of interest 7 decreased to 94.2% at 3 months, 96.7% at 24 months. In group BHR, the bone mineral density of femoral neck was restored to the pre-operation level at 6 months. The bone mineral density in superior-lateral zone of femoral neck decreased to 97.1% at 3 months and increased to 107.4% at 24 months respectively. The bone mineral density in inferior-medial zone of femoral neck increased to 117.9% at 24 months. CONCLUSION: The bone stock of proximal femur can be well preserved and recovered quickly after hip resurfacing arthroplasty.

Recurrent Hip Dislocation Following Total Hip Arthroplasty: Treatment with Sagittal Spinal Deformity Correction: A Case Report.

CASE: A 63-year-old woman with lumbar degenerative kyphosis who had undergone total hip arthroplasty 34 months previously presented after having multiple episodes of anterior hip dislocation; evaluation also revealed progressive osteoarthritis in the contralateral hip joint. The patient was managed with sagittal correction with pedicle subtraction osteotomy, which resulted in optimal positioning of the acetabular component and an upright posture. The patient had had no additional dislocation events in the involved hip and had reduced pain in the contralateral hip at the time of the 2-year follow-up. CONCLUSION: It is important to evaluate and address preexisting sagittal imbalance before performing total hip arthroplasty. However, for patients with neglected sagittal imbalance resulting in recurrent hip dislocation after total hip arthroplasty, sagittal deformity correction may be beneficial.

Dissociation of Polyethylene Liner of the Dual Mobility Acetabular Component after Closed Reduction of Dislocation: A Case Report.

A dual mobility acetabular component has a structure that combines a polyethylene liner and a femoral head, unlike the general design of acetabular cups, making the dissociation of a polyethylene liner highly unlikely. In addition, it increases the range of motion and reduces the possibility of dislocations by increasing a jump distance. A fifty-one-year-old male who had received total hip arthroplasty with the dual mobility acetabular component visited a hospital for a posterior hip dislocation 10 weeks after the operation. At the emergency room, closed reduction was performed and the dislocation was reduced. However, plain imaging test revealed polyethylene liner dissociation after the closed reduction. Revision surgery was performed. We will report a rare case of early dislocation of the dual mobility acetabular component and dissociation of polyethylene liner accompanied with a literature review.