Experimental periprosthetic fractures with collarless polished tapered cemented stems.

PURPOSE: After cemented total hip arthroplasty, the risk of periprosthetic fracture (PPF) of taper-slip stems is higher than that of composite-beam stems. We aimed to assess the conditions resulting in PPFs of taper-slip stems using a falling weight. METHODS: Taper-slip stems were fixed to five types of simulated bone models using bone cement, and the fractures were evaluated by dropping stainless-steel weights from a predetermined height onto the heads. The periprosthetic fracture height in 50% of the bone models (PPFH50) was calculated using the staircase method. RESULTS: For the fixation with 0° of flexion, the values for PPFH50 were 61 ± 11, 60 ± 13, above 110, 108 ± 49, and 78 ± 12 cm for the cobalt-chromium-molybdenum alloy, stainless steel alloy (SUS), titanium alloy (Ti), smooth surface, and thick cement mantle models, respectively; for the fixation with 10° of flexion (considering flexure), the PPFH50 values were 77 ± 5, 85 ± 9, 90 ± 2, 89 ± 5, and 81 ± 11 cm, respectively. The fracture rates of the polished-surface stems were 78.6 and 35.7% at the proximal and distal sites, respectively (p < 0.05); the fracture rates of the smooth-surface stems were 14.2 and 100%, respectively (p < 0.05). CONCLUSION: The impact tests demonstrated that the conditions that were less likely to cause PPFs were use of Ti, a smooth surface, a thick cement mantle, and probably, use of SUS.

Validity of a preoperative scoring system for surgical management of periprosthetic hip infection: one-stage vs. two-stage revision.

INTRODUCTION: There are no widely accepted algorithms for determining optimal treatment for periprosthetic joint infection (PJI). Our study aimed to confirm the validity of a previously published scoring system in a larger number of patients to support a rational surgical treatment strategy for periprosthetic hip infection. MATERIALS AND METHODS: Between February 2001 and December 2020, we performed 155 consecutive revision total hip arthroplasties (THAs) for PJI, with mean follow-up of 6 years. One-stage revision THA was performed in 56 hips and two-stage revision THA in 99 hips. Prosthesis survival from recurrent infection was determined by Kaplan-Meier analysis, using implant removal as the endpoint. The pre-operative scoring system (full score of 12 points), including 6 essential elements, was retrospectively evaluated. RESULTS: The 10-year survival rates were 98% for one-stage (95% confidence interval [CI], 94-100) and 87% (95% CI, 79-96) for two-stage revision THA. Multivariate Cox regression analysis provided a total preoperative score as an independent risk factor for implant removal (hazard ratio, 0.17; 95% CI, 0.06-0.49; p < 0.001). The sensitivity and specificity at the cut-off of 4 points on the scoring system were 80% and 91%, respectively. The average score for one-stage revision THA in successful and failed cases were 8.9 and 6.0, and for two-stage revision THA were 6.5 and 3.9, respectively. We found significant differences between successful cases in one- and two-stage revision THA (p < 0.05). CONCLUSIONS: The preoperative scoring system was useful for managing PJI. One-stage revision THA is recommended in patients scoring ≥ 9 points, and meticulously performed two-stage revision THA is encouraged for patients scoring ≥ 4 points.

Treatment strategies for recurrent dislocation following total hip arthroplasty: relationship between cause of dislocation and type of revision surgery.

BACKGROUND: There are many therapeutic options for dislocation following total hip arthroplasty (THA). The aim of this study was to evaluate the results of revision surgery for dislocated hips. METHODS: Between November 2001 and December 2020, 71 consecutive revision hip surgeries were performed at our institution for recurrent dislocation following THA. We conducted a retrospective study of all 65 patients (71 hips), who were followed for a mean of 4.7 ± 3.2 years (range, 1-14). The cohort included 48 women and 17 men, with a mean age of 71 ± 12.3 years (range, 34-92). The mean number of previous surgeries was 1.6 ± 1.1 (range, 1-5). From intraoperative findings, we created six categories of revision hip surgery for recurrent dislocation following THA: open reduction and internal fixation (2 hips); head change or liner change only (6 hips); cup change with increased head size only (14 hips); stem change only (7 hips); cup and stem change (24 hips); and conversion to constrained cup (18 hips). Prosthesis survival was analyzed by the Kaplan-Meier method, with repeat revision surgery for re-dislocation or implant failure as the endpoint. A cox proportional hazards model was used for risk factors of re-revision surgery. RESULTS: Re-dislocation occurred in 5 hips (7.0%) and implant failure in 1 hip (1.4%). The 10-year survival rate was 81.1% (95% confidence interval, 65.5-96.8). A Dorr classification of "positional" was a risk factor for re-revision surgery due to re-dislocation. CONCLUSION: Clear understanding of the cause of dislocation is essential for optimizing revision procedures and improving the rate of successful outcomes.

Trochanteric Claw Plate Fixation for Greater Trochanteric Fracture or Osteotomy in Total Hip Arthroplasty.

This study retrospectively evaluated 41 consecutive open reductions and internal fixations following primary or revision total hip arthroplasty, which required trochanteric claw plate fixation for greater trochanteric fracture or osteotomy between January 2008 and December 2020. The mean duration of clinical follow-up was 4.2 years (range, 1-13 years). The patients included 13 men and 28 women, with a mean age of 68 years (range, 32-87 years). The indications for intervention included trochanteric osteotomy, intraoperative fracture, and non-union including postoperative fracture in 6, 9, and 26 cases, respectively. The mean Merle d'Aubigné Clinical Score improved from 9.4 points (range, 5-15 points) pre-operatively, to 14.3 points (range, 9-18 points) at the last follow-up. Bone union occurred in 35 cases (85%), while implant breakage occurred in four cases. At the last follow-up, the mean Merle d'Aubigné Clinical Scores of bone union and non-union were 15.3 and 14.1, respectively (p=0.48). The Kaplan-Meier survival rate, with the endpoint being revision surgery for pain, non-union, dislocation, or implant breakage, at 10 years was 80.0% (95% confidence interval: 62.6-97.4%). Greater trochanteric fixation using a trochanteric claw plate yielded successful results.

Can serum C-reactive protein determine the timing of reimplantation in two-stage revised arthroplasty for periprosthetic hip infection?

BACKGROUND: There are no definitive guides to determine the timing of reimplantation in two-stage revision total hip arthroplasties (THA) for periprosthetic joint infection (PJI). This study was to design to support a rational strategy of surgical treatment using serum C-reactive protein (CRP). METHODS: We analyzed a total of 75 hips for PJI in the process of performing two-stage and multiple-stage revision THAs. CRP level was retrospectively evaluated every week and transformed to log2 (CRP) using a logistic regression model. Prosthesis survival from recurrent infection was determined by Kaplan-Meier analysis, using implant removal as the endpoint. Receiver operating characteristic curves were calculated using each log2 (CRP) to assess predictions of recurrent infection. RESULTS: The 10-year survival rates were 85% (95% confidence interval, 76-95) and 100% for two-stage and multiple-stage revision THAs, respectively. Preoperatively, at 1, 2, 3, and 5 weeks, log2 (CRP) was not associated with recurrent infection. In failed two-stage revision THAs, log2 (CRP) at 3 weeks divided by that at 2 weeks showed a significant difference. Failure was associated with a ratio of >4.0 for the CRP level between 3 and 2 weeks. CONCLUSION: In two-stage revision THA for PJI, patients with CRP elevation from 2 weeks to 3 weeks, especially 4-fold elevation, suggests the need for further debridement and postponement of second-staged reimplantation.

A Possible Protective Effect of the 'Cam Deformity' on Femoral Neck Fracture: The Relationship between Hip Morphology and the Types of Hip Fracture.

We retrospectively evaluated the cases of 169 hip fracture patients, their previous fractures, and the contralateral hip joint's morphology. A history of contralateral hip fracture was present in 23 patients (Contra group). The other patients had a unilateral hip fracture: a trochanteric fracture (Troch group, n=73) or a femoral neck fracture (Neck group, n=73). In the Troch and Neck groups, we used anteroposterior and cross-table axialview radiographs of the contralateral hip to evaluate the proximal femur's anatomy. In the Contra group, the concordance rate between the first and second types of hip fracture was 65.2%, and the second hip fracture's morphology indicated that the trochanteric fracture had a cam deformity in terms of the femoral head-neck ratio. The average alpha angle and femoral head-neck offset in the Troch group were significantly larger than those in the Neck group. In the Neck group, pistol-grip deformities of Arbeitsgemeinschaft für Osteosynthesefragen types B1 (subcapital), B2 (transcervical), and B3 (displaced) were observed in 42.1%, 75%, and 6% of cases, respectively. There was a smaller alpha angle and a larger femoral head-neck offset in the contralateral hip of femoral neck fractures; thus, the "cam deformity" may protect against femoral neck fractures.

Sonication of Extracted Implants Improves Microbial Detection in Patients With Orthopedic Implant-Associated Infections.

BACKGROUND: We assessed whether combining the conventional culture and implant sonicate fluid culture (SFC) methods increased the diagnostic accuracy of orthopedic implant-associated infection (OIAI). METHODS: Consecutive patients (n = 66) undergoing implant removal (OIAI, 17; non-OIAI, 49) were evaluated prospectively. We analyzed 493 samples (39 preoperative joint aspirates, 243 peri-implant tissue specimens, 124 implant sonication, 67 controls, and 20 water bath samples). OIAI was preoperatively evaluated based on clinical evidence of infection or aspirate culture (AC). Conventional methods required positive results in either preoperative ACs or intraoperative tissue cultures (TCs), whereas the combination method required at least 1 positive culture among 3 sources (AC, TC, or SFC). The application of SFC and the detection rate, sensitivity, and specificity of the diagnostic methods were assessed. RESULTS: No controls or water bath samples harbored bacteria. Three patients (18%) were detected by SFC only and Peptostreptococcus and Corynebacterium species were isolated by SFC only. The OIAI detection rate attributable to SFC was significantly higher than that of TC (61% vs 36%; P = .02). The sensitivities of AC, TC, and SFC at a cutoff point of 1 colony-forming unit/plate and 1 positive culture were 60%, 59%, and 71%, respectively. At a cutoff point of 2 positive cultures, the combination (vs conventional) method showed significantly greater sensitivity (71% vs 47%; P = .008). CONCLUSION: By incorporating SFCs into conventional culture methods, the diagnostic accuracy in the context of OIAI was significantly improved.

Reattachment of an osteotomized greater trochanter in total hip arthroplasty using an ultra-high molecular weight polyethylene fiber cable.

BACKGROUND: The optimum approach in total hip arthroplasty (THA) should reduce the risk of postoperative dislocation or limping, be applicable in every case, and be reusable in the future. The purpose of this study was to introduce our transgluteal approach for THA and to evaluate the type and frequency of complications around the greater trochanter. METHODS: This study retrospectively evaluated 892 THA cases between January 2010 and March 2015 performed using our transgluteal approach that osteotomized only the lateral anteroinferior greater trochanter. The trochanteric fragment was reattached using one of three different protocols: Group A, three non-absorbable polyester sutures; Group B, two non-absorbable polyester sutures and one ultra-high molecular weight polyethylene (UHMWPE) fiber cable; or Group C, two UHMWPE fiber cables. Postoperative complications were assessed and recorded, and univariate logistic regression analyses were performed to determine whether risk factors and radiological complications around the greater trochanter were correlated. RESULTS: None of the hips required revision for infection, dislocation, or limping. The rate of radiological complications around the greater trochanter at 1 year was 19.2% in Group A, 16.3% in Group B, and 7.9% in Group C (p < 0.001). Risk factors for radiological complications included the patient's disease or the surgeon's experience in Group A and the patient's age or the surgeon's experience in Group C. In the relationship between postoperative pain around the greater trochanter and radiological complications, there were no significant differences in all groups; no group interaction was observed (p= 0.3875). CONCLUSION: The UHMWPE fiber cable was effective to reduce complications of the reattached osteotomized greater trochanter in THA.

Bone Remodeling in Acetabular Reconstruction Using a Kerboull-Type Reinforcement Device and Structural Bone-Grafting in Total Hip Arthroplasty.

BACKGROUND: The purpose of this study was to identify the long-term durability of the Kerboull-type reinforcement device (KT plate) in acetabular reconstruction for massive bone defects, assessing the remodeling of structural bone grafts. METHODS: This study retrospectively evaluated 106 hips that underwent acetabular reconstruction using a KT plate between November 2000 and December 2010. Thirty-eight primary total hip arthoplasties (THAs) and 68 revised THAs were performed, and the mean duration of clinical follow-up was 8 years (5-14 years). Regarding reconstructing the acetabular bone defects, autografts were used in 37 hips, allografts in 68 hips, and A-W glass ceramics in 2 hips. RESULTS: One hip exhibited radiological migration and no revision for aseptic loosening. The mean Merle d'Aubigné Clinical Score improved from 7.5 points (4-12 points) preoperatively to 10.9 points (9-18 points) at the last follow-up. The Kaplan-Meier survival rate for radiological migration of primary and revised THAs at 10 years was 100% and 97% (95% confidence interval: 96%-100%), respectively. Bone remodeling was evaluated using the radiological demarcation at the bone-to-bone interface, and an improvement of 100% in primary THAs and 94% in revised THAs was observed. CONCLUSION: For massive bone defects, acetabular reconstruction using the KT plate with a structural bone grafting can yield successful results.

In vivo serum concentration of vancomycin in antibiotic-loaded acrylic cement for the treatment and prevention of periprosthetic hip infection.

BACKGROUND: Although antibiotic-loaded acrylic cement (ALAC) is used to prevent and treat periprosthetic hip infection, it is unknown how much antibiotic is deposited in the body in vivo, how high the serum concentration rises, or how long its effects last. The aim of this study was firstly to determine the amount of vancomycin (VCM) deposited as ALAC in the body, and secondly to assess the safety and drug elution profile of VCM in ALAC. METHODS: We administered VCM to prevent infection after total hip arthroplasty (THA) or to treat patients with methicillin-resistant Staphylococcus aureus. Patients were classified into two groups: a low-dose group (21 hips) that received primary THA for high-risk cases, revision THA without infection, or one-staged revision THA for infection; and a high-dose group (6 hips) that received cement beads during a two-staged revision THA. The amount of VCM placed as ALAC into the hip was calculated using the remaining ALAC. The serum concentrations of VCM and creatinine were evaluated at postoperative days 1, 4, 7, 14, and 28, and at 3 and 6 months. RESULTS: The mean amount of VCM placed as ALAC into the hip was 0.9 g and 3.4 g for cemented THA and cement beads, respectively (P < 0.0001). The mean serum concentration of VCM from ALAC in the high-dose group was significantly increased compared with that in the low-dose group on postoperative days 1, 4, 7, 14, and 28 (P < 0.0001), but it remained within a clinically safe range. No significant differences were observed between the preoperative and postoperative serum creatinine levels of either group. CONCLUSION: The average serum concentrations of VCM from ALAC were always less than the effective blood concentration, and were detectable until 6 months after surgery.

Long-term results of acetabular reconstruction using three bulk bone graft techniques in cemented total hip arthroplasty for developmental dysplasia.

PURPOSE: The aims of this retrospective study were to firstly introduce three practical bulk bone graft techniques based on acetabular morphology for dysplasia and secondly evaluate the long-term durability of acetabular reconstruction using those techniques combined with cemented total hip arthroplasty (THA). METHODS: The study comprised 101 consecutive THAs with a minimum follow-up of ten years; these procedures were categorised as being L shape (n = 58), Wall (n = 33) and D shape (n = 10) types. RESULTS: At the last follow-up, all bone grafts acquired trabecular reorientation, and no evidence of revision for aseptic or radiological loosening was noted. CONCLUSIONS: These bone graft techniques will be effective for improving the management of dysplasia in cemented THA by providing both acetabular reconstruction and cement containment.

Pre-operative scoring system to determine the surgical strategy for periprosthetic hip infection.

PURPOSE: The aim of this study was to evaluate the results of one- and two-stage revision total hip arthroplasties (THAs) and to determine a rational surgical treatment strategy for periprosthetic hip infections. METHODS: We constructed a 12-point preoperative scoring system to suggest either one- or two-stage revision THAs, based on a retrospective analysis of 55 operative procedures. Prosthesis survival was analysed using the Kaplan-Meier method, and the validity of the scoring system was evaluated using receiver-operating characteristic curves. RESULTS: At the end point of implant removal due to recurrent infection, the ten year survival rates were 94 and 87% for one- and two-stage revision THAs, respectively. One-stage revision THA was recommended for patients scoring >9 points. The risk of recurrent infection in patients scoring 4 points was 83%. The sensitivity and specificity of a cut-off value of 4 points, determined by the scoring system, were 83 and 100%, respectively. CONCLUSIONS: The novel pre-operative scoring system was useful for the management of periprosthetic hip infections.

Induction of autoimmune arthritis after direct injection of bone marrow cells from arthritis-prone SKG/Jcl mice into bone cavity of normal mice.

SKG/Jcl (SKG) mice spontaneously develop T cell-mediated autoimmune arthritis and may be an effective model for studying human rheumatoid arthritis. We sought to confirm that arthritis in SKG mice was caused by stem cell disorders. We induced systemic arthritis in normal C57/BL6 (B6) mice (H-2(b) type) by injecting lineage-negative (lin(-)) immature cells isolated from bone marrow cells (BMCs) of SKG mice (H-2(d) type) directly into bone cavities. Twenty weeks later, we analyzed arthritis scores, hematoxylin-eosin (H-E) staining and tartrate-resistant acid phosphatase (TRAP) staining in ankle joints, H-2 type of hematolymphoid and osteoblast-like cells, serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) and percentages of CD4(+) T cells and osteoblast-like cells expressing receptor activator of nuclear factor kappa-B ligand (RANKL) in recipient mice. Donor-derived hematolymphoid cells and osteoblast-like cells had completely replaced donor-derived cells in the recipients (H-2(b) to H-2(d)). All recipients showed severe joint swelling with hyperemia and developed hypertrophic synovitis with lymphocytes accumulated around joints. All recipients also had higher TNF-α and IL-6 levels than untreated B6 controls. Furthermore, the percentages of CD4(+) T cells and osteoblast-like cells expressing RANKL and the number of TRAP(+) cells were greater in treated animals. Donor-derived hematolymphoid cells and osteoblast-like cells persisted in these recipients and promoted autoimmune arthritis and an increase in osteoclasts. Because autoimmune arthritis may be associated with abnormal lin(-) immature cells, patients with intractable autoimmune arthritis may be treated by replacing these cells with direct injection of lin(-) immature cells isolated from normal BMCs.

Subtrochanteric shortening osteotomy combined with cemented total hip arthroplasty for Crowe group IV hips.

BACKGROUND: Total hip arthroplasty (THA) is a challenging surgical procedure that can be used to treat severely dislocated hips. There are few reports regarding cemented THAs involving subtrochanteric shortening osteotomy (SSO), even though cemented THAs provide great advantages because the femur is generally hypoplastic with a narrow, deformed canal. PURPOSES: We evaluated the utility of cemented THA with SSO for Crowe group IV hips, and assessed the relationship between leg lengthening and nerve injury. Our goal was to describe surgical techniques for optimizing surgical outcomes while minimizing the risk of nerve injury. METHODS: We retrospectively reviewed 34 cases of cemented THAs with transverse SSO for Crowe group IV. Prior to surgery, mean hip flexion was 93.1° (40°-130°). The mean follow-up period was 5.2 years (3-10 years). RESULTS: Bone union took an average of 7.7 months (3-24 months). Mean leg lengthening was 40.5 mm (15-70 mm) and was greater in patients without hip flexion contracture. None of the patients experienced any nerve injuries associated with leg lengthening, and radiographic evidence of loosening was not observed at the final follow-up. CONCLUSIONS: SSO combined with cemented THA is an effective treatment for severely dislocated hips. Leg lengthening is not necessarily associated with nerve injuries, and the likelihood of this surgical complication may be related to the presence of hip flexion contracture.

Chronic Expanding Hematoma With Progressive Osteolysis After Total Hip Arthroplasty: A Case Report.

A 31-year-old man without any other medical history developed severe hip pain seven years after right primary total hip arthroplasty (THA). Radiography revealed extensive progressive osteolysis around the cup and stem. Periprosthetic infections and adverse reactions to the metal debris were absent. Right revision THA was performed, and chronic expanding hematoma (CEH) was diagnosed based on a comprehensive assessment. CEH should be diagnosed early because progressive osteolysis may generate an extensive hematoma. Thus, it should be considered when progressive osteolysis of an unknown cause is encountered after THA.

Trunnionosis in Metal-on-Polyethylene Total Hip Arthroplasty With Periprosthetic Infection: A Case Report.

A 67-year-old man who underwent right hemiarthroplasty and left total hip arthroplasty (THA) experienced left hip pain two years previously. No previous diagnosis was made at other hospitals. Radiography revealed left hip trunnionosis because of stem-neck shortening, with periprosthetic joint infection (PJI) spreading to both hips. Bilateral revision THA was performed, but the treatment was difficult due to the delayed diagnosis, necessitating the extraction of the well-fixed stem for PJI. Trunnionosis is caused by implant-related, surgical, and patient factors, and early diagnosis is important because of its association with PJI. Furthermore, even implants with few reports of trunnionosis can lead to this complication. Surgeons should always consider that performing THA using a large-diameter head predisposes the patient to trunnionosis.

The modified Spitzy shelf acetabuloplasty for the dysplastic hip.

Aims: Although there are various pelvic osteotomies for acetabular dysplasia of the hip, shelf operations offer effective and minimally invasive osteotomy. Our study aimed to assess outcomes following modified Spitzy shelf acetabuloplasty. Methods: Between November 2000 and December 2016, we retrospectively evaluated 144 consecutive hip procedures in 122 patients a minimum of five years after undergoing modified Spitzy shelf acetabuloplasty for acetabular dysplasia including osteoarthritis (OA). Our follow-up rate was 92%. The mean age at time of surgery was 37 years (13 to 58), with a mean follow-up of 11 years (5 to 21). Advanced OA (Tönnis grade ≥ 2) was present preoperatively in 16 hips (11%). The preoperative lateral centre-edge angle ranged from -28° to 25°. Survival was determined by Kaplan-Meier analysis, using conversions to total hip arthroplasty as the endpoint. Risk factors for joint space narrowing less than 2 mm were analyzed using a Cox proportional hazards model. Results: The mean Merle d'Aubigné clinical score improved from 11.6 points (6 to 17) preoperatively to 15.9 points (12 to 18) at the last follow-up. The survival rates were 95% (95% confidence interval (CI) 91 to 99) and 86% (95% CI 50 to 97) at ten and 15 years. Multivariate Cox regression identified three factors associated with radiological OA progression: age (hazard ratio (HR) 2.85, 95% CI 1.05 to 7.76; p = 0.0398), preoperative joint space (HR 2.41, 95% CI 1.35 to 4.29; p = 0.0029), and preoperative OA (HR 8.34, 95% CI 0.94 to 73.77; p = 0.0466). Conclusion: Modified Spitzy shelf acetabuloplasty is an effective joint-preserving surgery with a wide range of potential indications.

Endofemoral Shooting Technique for Removing Well-fixed Cementless Stems.

Background: The removal of a well-fixed cementless stem poses technical challenges. The aim of this study was to evaluate the outcomes of our endofemoral extraction technique established in 2001. Methods: Between January 2001 and December 2016, 118 consecutive revisions following bipolar or total hip arthroplasty, which required cementless femoral stem removal, were performed at our institution. This retrospective study evaluated 106 patients (108 hips) who were followed up for a mean of 9.2 years (range, 5-20 years). The patients included 15 men and 91 women with a mean age of 65 years (range, 33-87 years). Endofemoral extracted stem removal was performed as follows. Multiple Kirschner wires were sequentially inserted into the interface between the implant and cortical bone, after which the implant was detached using a thin chisel. After the cementless stem was removed, it was replaced with a cemented stem using an autograft, as needed. Radiological loosening of the femoral stem was defined as definite or probable loosening, based on the criteria of Harris et al. Prosthesis survival was analyzed using the Kaplan-Meier method, with the endpoint set as repeat revision surgery for stem loosening or femoral fracture. Results: Re-revision surgery was performed in 7 hips. Stem loosening was observed in 4 hips, and the mean subsidence was 0.3 mm (0-3 mm). The 10-year survival rate was 97.7% (95% confidence interval, 93.2-100). Conclusions: Our technique for removing well-fixed cementless stems yielded successful results.

8-Prenylnaringenin tissue distribution and pharmacokinetics in mice and its binding to human serum albumin and cellular uptake in human embryonic kidney cells.

8-Prenylnaringenin (8-PN), a hop flavonoid, is a promising food substance with health benefits. Compared with nonprenylated naringenin, 8-PN exhibits stronger estrogenic activity and prevents muscle atrophy. Moreover, 8-PN prevents hot flushes and bone loss. Considering that prenylation reportedly improves the bioavailability of flavonoids, we compared the parameters related to the bioavailability [pharmacokinetics and tissue distribution in C57/BL6 mice, binding affinity to human serum albumin (HSA), and cellular uptake in HEK293 cells] of 8-PN and its mother (non-prenylated) compound naringenin. C57/BL6 mice were fed an 8-PN or naringenin mixed diet for 22 days. The amount of 8-PN (nmol/g tissue) in the kidneys (16.8 ± 9.20), liver (14.8 ± 2.58), muscles (3.33 ± 0.60), lungs (2.07 ± 0.68), pancreas (1.80 ± 0.38), heart (1.71 ± 0.27), spleen (1.36 ± 0.29), and brain (0.31 ± 0.09) was higher than that of naringenin. A pharmacokinetic study in mice demonstrated that the C max of 8-PN (50 mg/kg body weight) was lower than that of naringenin; however, the plasma concentration of 8-PN 8 h after ingestion was higher than that of naringenin. The binding affinity of 8-PN to HSA and cellular uptake in HEK293 cells were higher than those of naringenin. 8-PN bioavailability features assessed in mouse or human model experiments were obviously different from those of naringenin.