Expression of Acetabular Labral Vascular Endothelial Growth Factor and Nerve Growth Factor Is Directly Associated with Hip Osteoarthritis Pain: Investigation by Immunohistochemical Staining.

The acetabular labrum enhances hip joint stability and plays a key role in osteoarthritis (OA) progression. Labral nerve endings contribute to hip OA pain. Moreover, vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) are associated with pain. Consequently, we analysed VEGF and NGF expression levels in the labrum and their roles in OA. Labra obtained from OA patients were stained immunohistochemically, and labral cells were cultured and subjected to a reverse transcription (RT)-polymerase chain reaction (PCR) to analyse VEGF and NGF mRNA expression. VEGF and NGF expression were compared in each region of the labrum. Correlations between VEGF and NGF expression and age, body mass index, Kellgren-Lawrence grade, Harris Hip Score, the visual analogue scale (VAS), and Krenn score were analysed, and the RT-PCR confirmed the findings. VEGF and NGF expression were high on the labral articular side, negatively correlated with the Krenn score, and positively correlated with the VAS in early OA. VEGF and NGF mRNA expression increased significantly in patients with severe pain and decreased significantly in severely degenerated labra. In early OA, VEGF and NGF expression in the acetabular labrum was associated with the occurrence of hip pain; therefore, these factors could be effective targets for pain management.

Mechanical stretching induces calcification and cartilage matrix metabolism, causing degeneration of the acetabular labrum.

PURPOSE: The acetabular labrum plays an important role in joint lubrication, and damage to this structure leads to osteoarthritis. This study aimed to histologically classify the degree of degeneration of the acetabular labrum and to investigate the changes in gene expression induced by mechanical stretching. METHODS: We obtained acetabular labrum cells from patients with hip osteoarthritis during total hip arthroplasty (n = 25). The labrum was stained with safranin O, and images were histologically evaluated using a new parameter, the red/blue (R/B) value. The samples were divided into the degenerated group (D group: n = 18) and the healthy group (H group: n = 7) in accordance with the Kellgren-Lawrence (KL) grade. The cultured acetabular labral cells were subjected to loaded uniaxial cyclic tensile strain (CTS). After CTS, changes in gene expression were examined in both groups. RESULTS: Spearman's correlation analysis revealed that the R/B value was significantly correlated with the KL grade and the Krenn score. The expression levels of genes related to cartilage metabolism, osteogenesis and angiogenesis significantly increased after CTS in the H group, while gene expression in the D group showed weaker changes after CTS than that in the H group compared to the nonstretched control group. CONCLUSIONS: The degree of labral degeneration could be classified histologically using the R/B value and the KL grade. Mechanical stretching caused changes in gene expression that support the pathological features of labral degeneration.

Bipolar Hip Arthroplasty Using a Conjoined Tendon-preserving Posterior Approach in Geriatric Patients.

In bipolar hemiarthroplasty (BHA), it is important to preserve soft tissue to reduce the risk of postoperative dislocation. A variety of surgical approaches for BHA are available, but extra care is needed with muscle- and tendon-preserving approaches in geriatric patients. We investigated the usefulness of BHA using a conjoined tendon-preserving posterior (CPP) approach, in which only the external obturator muscle is dissected, in geri-atric patients. We retrospectively analyzed the cases of 40 femoral neck fracture patients (10 men, 30 women) aged ≥ 80 years who underwent BHA using the CPP approach. The patients' average age was 85.8 years (80-94 years). We examined the operation time, bleeding, preservation of short external rotator muscles, complica-tions, and stem alignment and subsidence from postoperative radiographs. Although gemellus inferior muscle injury was detected in 4 patients (10%), the hip joint stability was very excellent in all cases. There was no intraoperative fracture or postoperative dislocation. On postoperative radiographs, all femoral stems were in a neutral position. There was no stem subsidence in all 40 patients. BHA using the CPP approach appeared to be useful even in geriatric patients.

The Thickness of the Medial Wall of the Acetabulum Prevents Acetabular Fracture during the Insertion of a Cementless Cup in Total Hip Arthroplasty: A Biomechanical Study.

Intra-operative acetabular fracture is a total hip arthroplasty complication that can occur during cementless cup insertion, especially in osteoporotic patients. We conducted this biomechanical study to investigate the impact resistance of the acetabulum with simulated bones of different density by drop-weight impact testing. Low- and high-density polyurethane foam blocks were used as osteoporotic and healthy bone models, respectively. Polyurethane blocks were used as the acetabular cancellous bone. Composite sheets were used as the acetabu-lum's medial cortex. The testing revealed that the osteoporotic bone model's impact resistance was significantly lower than that the healthy bone model'. In the healthy bone model, even thin acetabular cancellous bone with ≥ 1 mm acetabulum medial cortex was less likely to fracture. In the osteoporotic bone model, fracture was pos-sible without ≥ 1 mm medial cortex of the acetabulum and thick acetabular cancellous bone. Although impac-tion resistance differs due to bone quality, the impaction resistance in this osteoporotic bone model was equiv-alent to that healthy bone model's when a thick medial wall was present. To avoid intra-operative acetabulum fracture, surgeons should consider both the bone quality and the thicknesses of the medial cortex and acetabu-lar cancellous bone.

Comparison of the accuracy of CT- and accelerometer-based navigation systems for cup orientation in total hip arthroplasty.

BACKGROUND: The accuracies of various navigation systems in total hip arthroplasty (THA) have been described; however, the accuracy of cup orientation with an accelerometer-based navigation system has not been reported. The purpose of this study was to compare the accuracies of computed tomography (CT)- and accelerometer-based navigation systems for cup orientation in THA. METHODS: In this prospective study, 30 patients who underwent cementless THA via anterolateral approach in the lateral decubitus position were analysed. A CT-based navigation system (30 hips) and an accelerometer-based navigation system (30 hips) were used simultaneously. The accuracy of cup orientation (absolute difference between intraoperative vs. postoperative measurements) was compared between the navigation systems using postoperative CT. RESULTS: The accuracy of cup inclination was 3.2 ± 2.4° in the CT-based navigation group and 4.1 ± 3.7° in the accelerometer-based navigation group (p = 0.3035). The accuracy of cup anteversion was 3.0° ± 2.5° in the CT-based navigation group and 6.8° ± 4.8° in the accelerometer-based navigation group. Cup anteversion was significantly more accurate with the CT-based navigation system than with accelerometer-based navigation (p = 0.0009). Multiple regression analysis demonstrated that the malposition in cup anteversion was positively correlated with the change in pelvic tilt and loosening of the reference antenna. CONCLUSIONS: Although, these results are only true for this specific accelerometer system, cup positioning was significantly more accurate with the CT-based navigation system than an accelerometer-based navigation in the lateral decubitus position. This is because of considerable discrepancies in the sagittal pelvic tilt, resulting in variability in cup anteversion angle with the use of an accelerometer-based navigation system.

Acetabular depth, an early predictive factor of acetabular development: MRI in patients with developmental dysplasia of the hip after open reduction.

Early prediction of future acetabular development is important to determine an additional surgery for developmental dysplasia of the hip (DDH). The purpose of this study was to investigate the predictive factors of acetabular development using MRI. We retrospectively investigated dislocated 40 hips and 34 normal hips in 37 pediatric patients (9 males and 28 females) with DDH who underwent open reduction after walking age. We evaluated the cartilaginous acetabulum and labrum of the patients using coronal MRI T2*-weighted images at 5 years of age. The mean age at the time of surgery was 22 months, and the mean age at the final survey was 19 years. We divided patients into two groups in accordance with the Severin classification at the final follow-up. Groups with good outcomes (affected 26 hips and unaffected 27 hips) and poor outcomes (14 hips and 7 hips) were compared using the MRI parameters on each side. Predictive factors of acetabular development were identified using univariate and multiple logistic regression analyses. Using multiple logistic regression analysis, labral acetabular roof depth and labral hip center distance at 5 years of age represented predictors after open reduction (odds ratio 0.27, P = 0.035; odds ratio 3.4, P = 0.028, respectively) on the affected side, and bony hip center distance represented a predictor on the unaffected side (odds ratio 2.6, P = 0.049). Acetabular development in the unaffected side could be predicted by bony assessment, while acetabular development in the affected side had to be assessed by labrum using MRI.

An accelerometer-based navigation system provides acetabular cup orientation accuracy comparable to that of computed tomography-based navigation during total hip arthroplasty in the supine position.

BACKGROUND: Inadequate acetabular component orientation is associated with postoperative impingement, dislocation, and accelerated polyethylene wear. Computed tomography (CT)-based navigation systems provide accuracy for total hip arthroplasty (THA) but are not available in all facilities. Accelerometer-based navigation systems are inexpensive, but their accuracy remains undetermined. This study compares the accuracy of cup orientation in THA using CT-based and accelerometer-based navigation systems. METHODS: This retrospective study included 35 consecutive patients (11 males, 24 females; mean age, 65 years) who underwent primary cementless THA via an anterolateral approach in the supine position. Both CT-based and accelerometer-based navigation systems were used simultaneously. The accuracy of cup orientation was compared between the two systems using postoperative CT. RESULTS: The accuracy of cup inclination was 2.7° ± 2.0° in the CT-based group and 3.3° ± 2.4° in the accelerometer-based group. The accuracy of cup anteversion was 2.8° ± 2.6° in the CT-based group and 3.4° ± 2.2° in the accelerometer-based group. No significant difference was observed in cup inclination (p = 0.29) or cup anteversion (p = 0.34) between CT-based and accelerometer-based navigation. CONCLUSIONS: The accuracy of cup positioning did not differ significantly between CT-based and accelerometer-based navigation systems.