A predictive model for hip abductor strength and knee extensor strength 12 months after total hip arthroplasty with an interaction term.

BACKGROUND: Identifying populations with poor muscle recovery after total hip arthroplasty (THA) is important for postoperative physical therapy. Preoperative muscle strength is a strong factor that determines postoperative muscle strength. However, this effect may depend on other factors. Thus, predictive models with interaction terms are important for accurately predicting postoperative muscle strength. This study aimed to develop a predictive model for lower muscle strength 12 months after THA which incorporates interaction terms. METHODS: Subjects were female patients with hip osteoarthritis who underwent unilateral THA. Patients with locomotor disorders, neurological disorders, or postoperative complications were excluded. Hip abductor and knee extensor strength were measured, and a generalized linear model approach with preoperative muscle strength, age, body weight, height, disease duration, physical activity, and leg extension as explanatory variables was used to identify factors that determine muscle strength 12 months after THA. Models with interaction terms between preoperative muscle strength and other explanatory variables were also examined. RESULTS: A total of 82 patients were analyzed. Preoperative muscle strength, age, body weight, physical activity, and disease duration were extracted as factors that significantly and independently determine hip abductor and knee extensor strength. The interaction term between preoperative muscle strength and age was identified as a factor that significantly determines knee extensor strength. Regression coefficients for preoperative knee extensor strength and postoperative muscle strength were significant when age was +1 SD, but not when age was -1 SD. CONCLUSIONS: The predictive model demonstrated that lower muscle strength 12 months after THA is determined by preoperative muscle strength, age, weight, physical activity, disease duration, and preoperative muscle strength, with the effect of preoperative muscle strength on knee extensor strength being dependent on age. When predicting postoperative knee extensor strength using preoperative muscle strength, it is important to consider the effect of age.

Identifying Deficits in Hip and Knee Muscle Strength on the Surgical and Nonsurgical Sides in Women up to 12 Months After Total Hip Arthroplasty.

OBJECTIVE: Regaining hip and knee muscle strength is important after total hip arthroplasty (THA). However, it is unclear if muscles other than those of the operated hip also lose strength. This study aimed to identify deficits in hip and knee strength on the surgical and nonsurgical sides in female patients up to 12 months after THA. METHODS: Participants were 91 female patients who had hip osteoarthritis and underwent unilateral THA. Forty-six community-dwelling women who were asymptomatic were selected as control participants. Patients with locomotor disorders or postsurgical complications were excluded. Maximal isometric strength of the hip flexors, extensors, and abductors and knee extensors and flexors on the surgical and nonsurgical sides were measured before THA and 3, 6, and 12 months thereafter. RESULTS: Twelve months after THA, hip flexion, extension, and abduction strength on the surgical side were 84.6%, 83.5%, and 76.2%, respectively, of those in individuals who were asymptomatic; at the same time point, those on the nonsurgical side were 94.8%, 83.9%, and 79.4%, respectively. Knee extension strength on the surgical side was 89.3% of that in individuals who were asymptomatic. Compared to individuals who were asymptomatic, nearly all muscles showed significantly lower strength on both sides up to 6 months after THA. CONCLUSION: At 12 months after THA, hip and knee strength on both the surgical and nonsurgical sides did not recover to the level observed in individuals who were asymptomatic. In particular, hip abductor strength on the surgical and nonsurgical sides were 76% and 79%, respectively, of that in individuals who were asymptomatic. IMPACT: At 12 months after THA, hip and knee strength on the surgical and nonsurgical sides did not recover to the level observed in individuals who were asymptomatic, suggesting that the nonsurgical side may be inappropriate as a control to assess strength recovery on the surgical side.

Relevance of physical activity with decrease in minimal joint space of the nonoperative hip in female patients after unilateral THA.

To clarify the relevance of physical activity (PA) with respect to a decrease in minimal joint space (MJS) of the nonoperative hip in female patients at 24 months post-contralateral total hip arthroplasty (THA). This prospective cohort study was conducted from six to 24 months post-THA. The subjects were 85 female patients with hip osteoarthritis (OA) who had undergone unilateral THA. The primary outcome was a change in MJS (ΔMJS). Daily step counts and moderate to vigorous physical activity were measured. To identify factors related to ΔMJS, a generalized linear model approach was used, with adjustment factors, Kellgren-Lawrence (KL) grade, PA, and interaction terms between PA and KL grade as explanatory variables. The interaction term between daily step count and KL grade was significant. The regression coefficient of the daily step count for ΔMJS was significant in the KL ≥ 1 group, but not in the KL = 0 group. A model with adjustment factors, an interaction term, and PA showed that the daily step count increased ΔMJS. PA was related to ΔMJS of the nonoperative hip in female patients with KL grade ≥1, but was not related to ΔMJS in patients without OA post-THA. Excessive daily step count may be a risk factor for a decrease in MJS of the nonoperative hip.

Hypoxia-induced endogenous prostaglandin E2 negatively regulates hypoxia-enhanced aberrant overgrowth of rheumatoid synovial tissue.

OBJECTIVE: During isometric exercise, the synovial joint tissue is prone to hypoxia, which is further enhanced in the presence of synovial inflammation. Hypoxia is also known to induce inflammatory cascades, suggesting that periodic hypoxia perpetuates synovitis in rheumatoid arthritis. We previously established an ex vivo cellular model of rheumatoid arthritis using the synovial tissue-derived inflammatory cells, which reproduced aberrant synovial overgrowth and pannus-like tissue development in vitro. Using this model, we investigated the regulatory mechanism of synovial cells against hypoxia in rheumatoid arthritis. METHODS: Inflammatory cells that infiltrated synovial tissue from patients with rheumatoid arthritis were collected without enzyme digestion, and designated as synovial tissue-derived inflammatory cells. Under normoxia or periodic hypoxia twice a week, their single-cell suspension was cultured in medium alone to observe an aberrant overgrowth of inflammatory tissue in vitro. Cytokines produced in the culture supernatants were measured by enzyme-linked immunosorbent assay kits. RESULTS: Primary culture of the synovial tissue-derived inflammatory cells under periodic hypoxia resulted in the attenuation of the spontaneous growth of inflammatory tissue in vitro compared to the culture under normoxia. Endogenous prostaglandin E2 (PGE2) production was enhanced under periodic hypoxia. When endogenous PGE2 was blocked by indomethacin, the aberrant tissue overgrowth was more enhanced under hypoxia than normoxia. Indomethacin also enhanced the production of tumor necrosis factor-α (TNF-α), macrophage colony-stimulating factor (M-CSF), and matrix metalloproteinase-9 (MMP-9) under periodic hypoxia compared to normoxia. The EP4-specific antagonist reproduced the effect of indomethacin. Exogenous PGE1 and EP4-specific agonist effectively inhibited the aberrant overgrowth and the production of the inflammatory mediators under periodic hypoxia as well as normoxia. CONCLUSIONS: The enhancing effect of periodic hypoxia on the aberrant overgrowth of rheumatoid synovial tissue was effectively down-regulated by the simultaneously induced endogenous PGE2.

A Rare Bone Erosion due to Fibroma of the Tendon Sheath.

Introduction: Fibroma of the tendon sheath (FTS) is a soft-tissue tumor strongly attaches to the tendon sheath. The most common tumor which causes bone erosion is giant cell tumor of the tendon sheath while the erosion is quite rarely caused by FTS. Case Report: A 50-year-old housewife presented a swelling around the A1 pulley of the right third finger as well as bone erosion and a trigger finger. Against our preoperative suspect as GTTS, the pathological findings showed FTS. The snapping disappeared after the surgery. At 2.5 years postoperatively, we found no recurrence. Conclusion: FTS can be added to one of the differential diagnoses for tumor presenting bone erosion in fingers though our case is rare.

Fifty-Six Years after Acrylic Hemiarthroplasty and after Then: A Case Report of Revision THA.

We revised an acrylic femoral hip prosthesis to a total hip prosthesis for an 86-year-old female. The implant was made of dental resin and had functioned for 56 years in situ, though its stem had broken. Because of no osteolytic reaction, the reconstruction was relatively easy. From the result of histologic and radiologic examination, the bio-inertness of material and uncemented fixation seemed to contribute the minimum bone loss and to the favorite spontaneous arthrodesis after providing good joint function in her middle age.

Nail insertion points in semi-extended nailing of tibial fractures and their influence on alignment: A retrospective cohort study comparing two nail insertion techniques.

INTRODUCTION: Semi-extended tibial nailing techniques include the extra-articular technique (EAT) and the patellar eversion technique (PET). These approaches differ regarding the exposure of the patellar retinaculum and the size of the surgical field. This study compared the postoperative alignment and intramedullary nailing entry points between the EAT and PET for tibial fractures. PATIENTS AND METHODS: A total of 54 patients (aged ≥18 years) who had undergone intramedullary nailing by the EAT (n = 29) or PET (n = 25) for a tibial shaft fracture were evaluated. The intramedullary nailing entry point and postoperative alignment were measured, and the 1-year postoperative follow-up results were compared. RESULTS: For the EAT and PET, the intramedullary nailing entry point was located at a mean distance of 4.04 mm medial to the optimal entry point and 0.27 mm lateral to the optimal entry point, respectively. The mean angular deformation observed in anteroposterior radiographs following surgery using the EAT and PET were 2.49° and 0.32° valgus, respectively. CONCLUSION: The intramedullary nailing entry point affected postoperative alignment. Intramedullary nailing may result in malalignment while performing the EAT due to the interference of the patella at the time of nailing.

Ceramic on Ceramic Bearings for Dysplastic Hips: Analysis of Uncemented 2,861 THAs.

We analyzed 2,861 uncemented primary total hip arthroplasties (THAs) with ceramic on ceramic bearing couple (C on C) for dysplastic hips followed up at least one year. The age at THA was 58 and the follow-up period was 6.8 (maximum of 21.4) years. Those belonged to Crowe's classification I were 76.4%, II were 14.6%, III were 7.0%, and IV were 2.0%. Two types of C on C were used: alumina on alumina (A on A) for 1979 hips and zirconia toughened alumina on zirconia toughened alumina (ZTA on ZTA) for 882 hips. Osteolysis was not detected. Dislocation occurred in six (0.2%) hips and the prevalence did not differ between A on A and ZTA on ZTA. Two liner fractures occurred only in A on A. Joint noise was detected in 79 (2.8%) hips. The prevalence of the noise was lower in ZTA on ZTA than in A on A. The revision rate was 0.5% and had no difference between A on A and ZTA on ZTA. All revisions in ZTA on ZTA were performed early after the initial surgery, while there was only one early revision in A on A. Taking endpoint as revision for any reason, the final survival rate was 97.2% for all C on C. At nine years after THA, the survival rate was higher in A on A than in ZTA on ZTA. Preventing the early failure by careful surgical procedure is essential to expect the same long-term durability of ZTA on ZTA as that of A on A.

Apophyseal dislocation of the body of the sternum in a child: a case report.

A 4-year-old boy received a blow to the chest and sustained an apophyseal dislocation of the body of the sternum. The dislocation was treated by open reduction and internal fixation. This type of injury is so rare that no studies could be found.

Frictional torque and wear of retrieved hip prostheses: a comparison between alumina/PE and Co-Cr/PE prostheses.

Frictional torque and wear were measured in 67 retrieved cups with internal diameters of 32 mm. Thirty cups were combined with alumina heads and 37 were combined with metal heads. A lower prevalence of cup loosening was observed in alumina-polyethylene implants than in metal-polyethylene implants. No relation between frictional torque and stability of implants was detected for either type, whereas retrieved cups of alumina-polyethylene implants showed lower frictional torque than those of metal-polyethylene implants. Less wear was observed in the cups of alumina-polyethylene implants (0.13 mm/y) than in those of metal-polyethylene implants (0.19 mm/y). Less wear was observed in cups without loosening than in those with loosening in both types. These results suggest that wear has a greater influence on the stability of cups than frictional torque.

Catastrophic stem taper wear in ceramic on polyethylene bearing couple: a case report.

A severe abrasion occurred at the stem taper 13 years after total hip arthroplasty. The bearing couple was 28 mm ceramic on polyethylene. The ceramic head had almost no damage, whereas the stem taper had severe damage. An ectopic bone probably contributed to the abrasion. The ectopic bone had grown to restrict the normal motion in the bearing couple and all stress and torque seemed to concentrate in the junction until the junction obtained mobility instead of the original bearing couple.

In vivo change of elastic property in polyethylene acetabular components.

Polyethylene is an elastic material. It is known that oxidative degradation of polyethylene occurs after sterilization by means of gamma irradiation. However, there have been few detailed reports with regard to the effects of this degradation on the mechanical property, especially in total hip prostheses. The purpose of this study was to examine the change in mechanical property of irradiated and non-irradiated polyethylene cups after implantation. Fifty-six ultra-high molecular-weight polyethylene (UHMWPE) cups retrieved at revision surgery were evaluated. Thirty-two cups were sterilized by gamma irradiation in air and 24 by ethylene oxide gas (EtO). To evaluate the mechanical property of the cup and its regional distribution, Vickers hardness was measured at nine points at the cross-section of the cups. In the irradiated cups, the hardness increased in proportion to the time from sterilization. This phenomenon was not found in the cups sterilized by EtO. Less change of hardness was observed in the cups sterilized by EtO than in those sterilized by irradiation. The gamma-irradiation in air actually affected the elastic property of cup polyethylene in vivo, although any difference in the wear rate was not detected between two sterilization methods. In cases with accelerated wear of the acetabular cup, other factors affecting wear should also be considered.

Gluteal Soft Tissue Necrosis After Transcatheter Angiographic Embolization for Pelvic Fracture: a Report of Two Cases.

In this paper, two cases of the gluteal soft tissue necrosis after pelvic fractures will be discussed. In the case of a 29-year-old man, a localized area of skin necrosis on the buttock appeared after transcatheter arterial embolization (TAE) of the right internal iliac artery (IIA). In the second case, a 52-year-old man, who was treated using TAE of the bilateral IIA's, developed an extensive area of necrosis in the gluteus maximus muscle with subsequent severe infection. In both cases, complete excision of the necrotic tissue and reconstructive flap surgery were imperative. Gluteal soft tissue necrosis is clinically important as one of the serious complications of TAE.