Assessment of micromotion at the bone-bone interface after coracoid and scapular-spine bone-block augmentation for the reconstruction of critical anterior glenoid bone loss-a biomechanical cadaver study.

BACKGROUND: Glenoid bone loss is among the most important risk factors for recurrent anterior shoulder instability, and a bony reconstruction is recommended in cases of critical bone loss (> 15%). The commonly used surgical techniques, including coracoid transfer, are associated with considerable complications. The aim of this study was to assess the motion at the glenoid-bone-block interface after coracoid and spina-scapula bone-block reconstruction of the anterior glenoid. METHODS: Twelve cadaveric shoulders were tested. A 20% bone defect of the anterior glenoid was created, and the specimens were randomly assigned for glenoid augmentation using a coracoid bone block (n = 6) or a scapular spine bone block (n = 6). The glenoid-bone interface was cyclically loaded for 5000 cycles with a force of 170 N. The micromotion was tracked using an optical measurement system (GOM ARMIS) and was evaluated with the GOM Correlate Pro software. RESULTS: The most dominant motion component was medial irreversible displacement for the spina-scapula (1.87 mm; SD: 1.11 mm) and coracoid bone blocks (0.91 mm; SD: 0.29 mm) (n.s.). The most medial irreversible displacement took place during the first nine cycles. The inferior reversible displacement was significantly greater for spina-scapula bone blocks (0.28 mm, SD: 0.16 mm) compared to coracoid bone blocks (0.06 mm, SD: 0.10 mm) (p = 0.02). CONCLUSIONS: The medial irreversible displacement is the dominant motion component in a bone-block reconstruction after a critical bone loss of the anterior glenoid. The spina-scapula and coracoid bone blocks are comparable in terms of primary stability and extent of motion. Thus, spina-scapula bone blocks may serve as alternatives in bony glenoid reconstruction from a biomechanical point of view.

Mechanical parameter assessment of fresh human cancellous bone of the femoral head in atraumatic femoral head necrosis and primary coxarthrosis.

BACKGROUND: Atraumatic femoral head necrosis is a rare pathological change of the femoral head. It is characterized by local necrosis of the cancellous bone as a result of reduced blood supply to the bone. Even today it remains unclear how to assess the hardness of the necrosis, whether it is soft tissue that is easily removed, or hard tissue that is difficult to resect. METHODS: Femoral heads with primary coxarthrosis were selected as a comparison group. For this purpose, 49 femoral heads obtained during total hip arthroplasty surgery with either condition (23 femoral head necrosis, 26 coxarthrosis) were transferred to the testing laboratory in fresh condition. Cylindrical specimens were obtained using a tenon cutter along the main trabecular load direction in the subchondral region of the femoral head. Additionally, thin bone slices were extracted proximal and distal to the specimens for density measurements. Brass plates were glued to the circular surfaces of the specimens. After curing of the adhesive, the specimens were mounted in the testing machine and destructive uniaxial compression tests were conducted. FINDINGS: The recorded mean compressive strengths and elastic moduli were almost identical for both groups, but the necrosis group showed significantly higher data scattering and range regarding the elastic modulus. The mean density of the coxarthrosis specimens was significantly higher than that of the necrotic specimens. INTERPRETATION: The mechanical properties of cancellous bone vary considerably in the presence of femoral head necrosis. The existence of hard necrosis implies a potential challenge regarding the clinical resection of these tissues.

Methods for bone quality assessment in human bone tissue: a systematic review.

BACKGROUND: For biomechanical investigations on bone or bone implants, bone quality represents an important potential bias. Several techniques for assessing bone quality have been described in the literature. This study aims to systematically summarize the methods currently available for assessing bone quality in human bone tissue, and to discuss the advantages and limitations of these techniques. METHODS: A systematic review of the literature was carried out by searching the PubMed and Web of Science databases from January 2000 to April 2021. References will be screened and evaluated for eligibility by two independent reviewers as per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies must apply to bone quality assessment with imaging techniques, mechanical testing modalities, and compositional characterization. The terms used for the systematic search were: "(bone quality". Ti,ab.) AND "(human bone specimens)". RESULTS: The systematic review identified 502 relevant articles in total. Sixty-eight articles met the inclusion criteria. Among them, forty-seven articles investigated several imaging modalities, including radiography, dual-energy X-ray absorptiometry (DEXA), CT-based techniques, and MRI-based methods. Nineteen articles dealt with mechanical testing approaches, including traditional testing modalities and novel indentation techniques. Nine articles reported the correlation between bone quality and compositional characterization, such as degree of bone mineralization (DBM) and organic composition. A total of 2898 human cadaveric bone specimens were included. CONCLUSIONS: Advanced techniques are playing an increasingly important role due to their multiple advantages, focusing on the assessment of bone morphology and microarchitecture. Non-invasive imaging modalities and mechanical testing techniques, as well as the assessment of bone composition, need to complement each other to provide comprehensive and ideal information on the bone quality of human bone specimens.

Assessment of the efficiency of different chemical treatments and ultrasonic cleaning for defatting of cancellous bone samples.

Our study aimed to asses the defatting efficiency of different methods, which are commonly used and easily available in the laboratory in order to find a method that is effective, convenient, safe, and economical. Cylindrical cancellous bone specimens were obtained from fresh-frozen human cadaver femoral condyles, cut into multiple small specimens (Ø8 × 2 mm), and assigned to two groups that were treated with either chemical solvent soaking (Solvent group) or ultrasonic cleaning (Ultrasound group). Each group was divided into several subgroups based on different treatments. Digital photographs were taken of each specimen. The difference of material density (Δρb), apparent density (Δρapp), and porosity (ΔP) before and after treatment were used as evaluation indicators. For the solvent group, in Δρb, only the combination of 99% ethanol and detergent solution showed a significant difference before and after treatment (P = 0.00). There was no significant difference in ΔP among acetone, the mixture of 99% ethanol and acetone, and the combination of 99% ethanol and detergent solution (P = 0.93). For the ultrasound group, the median of all subgroups in Δρapp and ΔP were all lower than the solvent group. The combination of 99% ethanol and detergent solution (v/v = 1:20), as well as the mixture of 99% ethanol and acetone (v/v = 1:1), seem to be the optimal defatting methods for 2 mm thick cancellous bone slices due to their effectiveness, availability, low-cost and safety. Chemical soaking for 24 h is more effective than ultrasonic cleaning with 99% ethanol or acetone for 20 or 40 min.